LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Class Water-Works Management and Maintenance BY WINFRED D. HUBBARD Assoc. M. Am. Soc. C. E. AND WYNKOOP KIERSTED M. Am. Soc. C. E., Consulting Engineer FIRST EDITION FIRST THOUSAND JOHN WILEY & SONS LONDON: CHAPMAN & HALL, LIMITED 1907 COPYRIGHT, 1907 BY WINFRED D. HUBBARD AND WYNKOOP KIERSTED ROBERT DRUMMOND COMPANY, PRINTERS, NEW YORK INTRODUCTION. THE maintenance and operation of a system of water-works is often believed to be a purely business proposition requiring essentially a business management. Regarded in a broad and comprehensive sense this view may be correct, for a far-seeing business management would not overlook the purely technical or scientific considerations which are necessarily involved in the management of a modern water- works system. The questions involved do not relate solely to the sale of a commodity supplied in the form of a water service, but also deal with the quality of the water supplied and the design, con- struction, and operation of the physical property by and through which the service is rendered. The selection of a water-supply drawn from an unpolluted source is highly desirable and inspires the confidence of the public in the management of water-works. This confidence, however, may be also secured when circumstances compel the use of a water drawn from polluted sources, provided the water be properly purified before use. Many natural waters contain more or less dissolved minerals, such as lime, magnesia, and iron, which are of themselves harmless, although in some instances objectionable when the water is required for some particular mechanical purpose. A soft water is always to be preferred for general use and is usually obtained from some surface source when a desirable selection can be made; but a moderately hard water is sometimes accepted for a public supply rather than incur the expense of the construction and operation of purification works. Turbidity and color, whether due to sedi- ment mechanically suspended in water or to vegetable stain, are offensive even when present in a moderate degree, although they may not render the water unwholesome. The introduction of pathogenic bacteria into a water-supply by contamination by sewage or other wastes is often productive of disease, and the human system iii 161547 IV INTRODUCTION. may be readily infected through the medium of drinking-water exposed to pollution of this nature. In consequence, sanitarians at the present time regard the quality of a water for hygienic purposes as closely associated with the bacterial life which it may contain. Taking into consideration the many things which have to be regarded in the selection and purification of water-supplies, it is clear that science can be serviceable to a water-works management in many ways, and the advantage of this kind of service should become more and more apparent as communities increase and prosper. If the aid of science is necessary to select a source of sup- ply free from dangerous pollution or to detect the presence of unob- served polluting influences, its aid is even more necessary in those cases where a source of supply, known to be polluted, requires thorough purification. It will not suffice to seek scientific assist- ance in such a case solely for the purpose of designing and constructing purification works, but it should also be retained for the purpose of insuring the satisfactory operation of these works and the preservation of the purity of the water after treatment. The safeguards of the public health in the way of constructed works need guardsmen to see that such works positively perform the functions expected of them at all times a service which may yet have to be supplied through the State or Federal government. From the foregoing it will appear that questions relating to the maintenance and operation of a system of water- works often depend for their proper solution upon the details of the original design, and the authors have deemed it advisable to outline to some extent in Part I the various methods by which a supply is secured. Part II deals particularly with matters more closely connected with the ordinary routine management of a water-works plant. In Part III consideration is given to questions which arise in the dealings of municipalities with private water companies. These questions have been brought to the attention of communities to a large extent during recent years by the trend toward municipal ownership of public utilities, and the principles involved in the fix- ing of water rates and the valuation of water-works property are presented in detail. CONTENTS. ' PART I. ON THE METHODS AND PRINCIPLES OF DEVELOPING, IMPROVING, AND STORING WATER-SUPPLIES. CHAPTER I. (w. K.) PAGE GROUND-WATER SUPPLY i CHAPTER II. (w. K.) RIVER-WATER SUPPLY 116 CHAPTER III. (w. K.) PUMPING-ENGINES 183 CHAPTER IV. (W. D. H.) IMPOUNDED SUPPLIES 204 PART II. MAINTENANCE AND OPERATION. CHAPTER I. (w. D. H.) PLANS AND RECORDS 218 CHAPTER II. (w. D. H.) EXTENSIONS 232 CHAPTER III. (w. D. H.) SERVICE CONNECTIONS 249 CHAPTER IV. (w. D. H.) METERS 265 v vi CONTENTS. CHAPTER V. (w. D. H.) PAOH CARE OF APPURTENANCES 280 CHAPTER VI. (w. D. H.) ALTERATIONS AND REPAIRS 298 CHAPTER VII. (w. D. H.) MAINTENANCE OF QUALITY 311 CHAPTER VIII. (w. D. H.) WATER WASTE 324 CHAPTER IX. (w. D. H.) ELECTROLYSIS 343 CHAPTER X. (w. D. H.) FIRE PROTECTION 352 CHAPTER XI. (w. D. H.) ACCOUNTS 36 1 CHAPTER XII. (w. D. H.) FINANCIAL MANAGEMENT 366 CHAPTER XIII. (w. D. H.) RULES AND REGULATIONS 377 CHAPTER XIV. (w. D. H.) ANNUAL REPORTS 380 PART III. (w. K.) FRANCHISE. WATER RATES. DEPRECIATION.... 385 Of THE UNIVERSITY OF WATER-WORKS MANAGEMENT AND MAINTENANCE. PART I. ON THE METHODS AND PRINCIPLES OF DEVELOPING, IMPROVING, AND STOR- ING WATER-SUPPLIES. CHAPTER I. GROUND-WATER SUPPLY. Quality. There is a charm and satisfaction attached to the cool, sparkling, and refreshing draught from a natural spring which incites a warm and enduring friendship for it. The perfect transparency of the water and its comforting and refreshing effect offer no hint that between the sparkling spring and its origin, the rainfall, the water possesses a long and obscure history. Per- haps the very obscurity of the precise nature of this history gives substance to the water's enchanting influence. But hidden as it is and with no visible signs that that history could have been any- thing but good in its long and untraceable source through the ground, there is apparent to the observer no tangible ground upon which to base the slightest suspicion of its purity so long as it is agreeable both to taste and sight. We therefore detect in ground-water the nearest approach to what may be popularly considered an ideal drinking-water. In fact we find it above suspicion and reproach in rural districts, almost invariably of first consideration in communities desiring to acquire a public 2 WATER-SUPPLIES. water-supply, and often regarded technically as of the highest rank among the various sources of water-supply. Sentiment and advertisement may stimulate a regard for a water of certain springs above that of other springs because the reputation thus gained usually centers around some medicinal qualities the water of such springs is supposed to possess. These special waters, the qualities of which are developed and sought out for special reasons and for special purposes, are not classed with the ordinary run of ground-waters available for the public water-supply. The basis of popular acceptance of a ground-water is usually its appearance and general palatability, and as a rule its appear- ance neither presents nor suggests evidence of present or past pollution. However, a little reflection must tell us that the rain- fall which washes the air and the surface of the ground must come in contact with contaminating influences to a greater or less degree, particularly in populous districts. Just how far we may encroach upon the domain of nature with our modern civilization and multiply instances of contamination upon her fair face without seriously polluting the rainfall, the source of all ground-water supply, is a question with which the water analyst and specialist is engaged. The further these investigations proceed along ra- tional lines the cruder appear the past methods and means of de- termining and judging of the wholesomeness of a ground- water and the more secure appear the provisions of nature to remove the impurities collected by the rainfall even in populous districts. In fact it is exceedingly doubtful that we yet realize and fully appreciate the true character, scope, and security of these pro- visions of nature. While some forms of bacterial life may be a source of danger in water, it is well known that bacterial life of other forms is a source of security. For instance the portion of the rainfall which enters the ground, even though it may be grossly polluted by surface contact with decaying matter, is quickly relieved of its dissolved organic impurities by the bacterial life which infests the surface soils and thrives upon the food which percolating water conveys to it. The ideal geological condition for the natural purification of water is to be found in a plane of well-ventilated sandy soil upon which the rainfall remains quite GROUKD-WATER SUPPLY. 3 uniformly distributed until: absorbed. A slow percolation through a comparatively few feet of such soil is sufficient for the purification of the rainfall. It is believed that pathogenic germs which water may have absorbed at the surface of the ground cannot survive a slow passage through such soil teeming with natural but to them antagonistic bacterial life. There is every reason to believe that a ground-water will be found quite as pure a comparatively few feet below the surface of a sandy soil as many feet below it, provided there are no more direct lines of communication than those through the voids of the sand. Sanitary analysis of a ground-water tells of the existing con- dition of the water as exemplified by the samples analyzed, of the probable present and past relation of the water with putres- cible organic matter, and of the possible contamination of the water from sources which cannot be detected by a personal inspec- tion of the territory receiving the rainfall. It is indicative of the degree to which the process of natural purification has progressed. It deals with existing facts and conditions, and when regularly made affords direct evidence of changes in the characteristics of a water as they occur. It can give little reliable information of a danger threatening eventually to become a source of contamination. A sanitary chemical analysis of a shallow ground-water con- cerns itself most with the existing state of the organic matter dissolved in the water analyzed, with the hardness of the water, and with the amount and condition of iron the water may con- tain, and with the total solids in solution. The term albuminoid ammonia used in recording the results of a chemical analysis indicates the undecomposed organic matter remaining in a water, the terms free ammonia and nitrites are considered respectively measures of progressive decomposition of organic matter, and the term nitrates represents the final result of decomposition when the decomposed elements of the organic matter have united with some mineral in the water. The trans- formation in its completeness is from putrescible organic matter to a stable mineral compound. A water which possesses evidence of all the intermediate steps in this transformation is considered imperfectly purified and may be still subject to the agencies pro- ducing the change. The presence of albuminoid and free ammonias 4 WATER-SUPPLIES. in small quantities or in a stable condition, the absence of nitrites, and the presence of the nitrates in either large or small amounts afford evidence of complete purification. Chlorine, usually present as common salt, has no direct chemical connection with the organic matter in water, is unchangeable and harmless, and is often regarded as an evidence of sewage pollution when the amount in the water exceeds that derived from natural sources. A few years ago, before biology demonstrated bacteria in some form to be the active agents of water purification and the real element to be feared in a polluted water, the result of a chemical analysis showing abnormal amounts of chlorine and nitrates would have been considered sufficient evidence of impurity to condemn the water because of past association with organic impurity. This conclusion was based upon the consideration that suspicion should attach to a water showing evidence of past pollution because of a fear that the conditions of complete natural purification may not remain perfect, rather than upon a consideration of danger in the presence of the compounds themselves. At the present time the conditions surrounding the natural filtration of ground-water are better understood, and better understanding inspires greater con- fidence in the process of natural purification and offers a stronger assurance of the certainty with which this operation of nature is conducted even when water is exposed to much more pollution than that naturally encountered. We are thus unable to draw rigidly the line of demarcation between a wholesome and an unwholesome water in so far as the quality of the water is revealed to us through the application of the science of chemistry alone. A knowledge of the physical char- acteristics of the territory from which the ground-water is supplied is often a more reliable guide than is the result of a chemical analy- sis alone. But both sources of information when fully developed should ba mutually supporting. The importance of the application of the science of bacteriology to the study of water-supply arises from the fact that drinking-water is a medium through which the bacilli of certain diseases may be imbibed and infection widely disseminated when the water is ex- posed to the pollution of infectious bacterial life without inter- GROUND-WATER SUPPLY. 5 mediate provision for its destruction or removal. The most prob- able source of disease germs in water is direct sewage contamina- tion, and therefore the bacteriologist searches for bacterial life characteristic of that known to exist in sewage in abundance. The presence in the water of sewage bacteria renders a water open to suspicion; the absence of this form of life allays suspicion even though the water may contain in small degree harmless forms of bacterial life native to water. Attention is called to the following analysis to illustrate the' effect which exposure of the rainfall to polluting matter upon the surface of the ground may have upon ground-water derived from springs and shallow wells. (In parts per million.) Wei If* J 300 feet from ssissippi River. 264.00 O.OI 0.014 None 9-6 0.6 6.8 Mississippi River water. 329.00 0-34 0-394 0.02 I . 7C Spring Brook. 126 .0 Trace 0.028 None 0.028 1C. * Free ammonia Albuminoid ammonia. . . . Nitrites Nitrates Oxygen consumed Chlorine. . The analysis of the water of the well near the Mississippi River indicates past pollution of a considerable amount but thorough subsequent purification. The bacteria in the well were few, numbering 20 to 40 per cubic centimeter and of a harmless variety. The water is also noteworthy in the regard that the sample, though taken about 50 feet below the surface of the ground, contains less dissolved minerals than the water of the adjoining river. The catch- ment area supplying the well from which the sample of water analyzed was taken is a sandy plane extensively cultivated and heavily fertilized. Doubtless the origin of the nitrogen and abnormal chlorine in the well-water is the fertilizer which is used upon the surface of the ground. The sample of water from the spring brook was taken near a spring which is supplied by rainfall upon a timbered, sandy,, un- cultivated catchment area. The analysis shows a small amount of organic pollution and accordingly is greatly in contrast with that of the sample supplied from the cultivated catchment area de- scribed in the preceding paragraph. 6 WATER-SUPPLIES. However, the character of the water from both the well and the spring brook could be substantially forecasted by survey of the physical characteristics of the respective catchment areas. Both waters were finally pronounced wholesome. Careful survey of the physical characteristics of a catchment area feeding comparatively shallow water bearing sand and gravel beds taken in connection with the information furnished by chem- ical and bacterial analysis of the water itself constitutes a com- prehensive sanitary survey, and when the results of the several examinations and analyses are interpreted with due mutual re- gard, we may reach substantially correct and safe conclusion as to the wholesomeness of a ground-water. A purely independent interpretation of the results of any one of the three elements re- ferred to may lead to a wrong conclusion; for instance the results of the analysis of the well-water given in the preceding table, if interpreted from a chemical point of view alone in accordance with the so-called standard of purity of a potable water as laid down in some of the older books on water-supply, would certainly lead to a rejection of that water, although in fact the pollution indicated is purely a matter of the past state of the water. Simi- larly a purely physical examination may discover sources of pollu- tion for the rainfall of such a character and so located as to arouse a suspicion that the polluting influence may extend to the sub- terranean waters and accordingly seek the assistance of both a chemical and bacteriological examination of the underground waters to either remove or confirm the suspicion. In a general way it may be stated that polluting matter upon the surface of the ground cannot be carried by absorbed rainfall into the underground water by percolating through intervening soil without purification. The danger of pollution of this sort lies in a direct communication between the surface and the under- ground waters, as, for instance, when surface-water overflows or passes through the curb of an open well or well-developed fissure channels. Polluting matter, particularly excrement deposited in covered excavations like the ordinary privy, is less exposed to natural purifying influences than similar matter upon the surface of the ground and accordingly is more to be feared, but the con t ami- GROUND-WATER SUPPLY. ^ nating effect of such matter so deposited is confined to a much more restricted area than many people would suppose when the excrement rests on the subsoil. However, if the excrement rest upon fissured rock exposed by the excavation of the privy, the connection between the receptacle and underground water may be direct and pollution proportionally extended. Water from deep wells possesses entirely different character- istics and cannot be regarded in the same category as shallow-well water. Usually such wells penetrate rock or alternate layers of porous and impervious materials and are supplied by the rainfall on remote catchment areas. As a rule the water from such wells is practically sterilized by a prolonged and slow process of filtra- tion. A visual survey can scarcely be made of the catchment area except where the geological structure of the surrounding territory is known by extended surveys, and a bacterial analysis of the water is scarcely necessary because prolonged filtration deprives the water of bacterial life. A chemical examination is practi- cally all that is needed, and this chiefly to determine the amount and character of dissolved mineral matter. With regard to water of this class the subject can be concisely covered by quoting from the reports made in connection with the water-supply of Galveston, Texas: "GALVESTON, TEXAS, November ipth, 1892. "To the Honorable Board of Commissioners of Water-works, Gal- veston, Texas. "Gentlemen: The following report is submitted, mainly from a sanitary standpoint, with respect to the new water-supply from artesian wells proposed for this city. ' ' The environment which gives character to deep-ground water is such that this class of water cannot be consistently compared with either surface or shallow- well waters. " Nitrogen in several chemical combinations influences the determination of the quality of water for potable purposes more than any other element in chemical combinations, since it is a principal constituent of the decaying organic matter with which all natural waters come in contact. Whether the source WATER-SUPPLIES. of this organic impurity in water is in decaying animal or vege- table matter, chemistry does not pretend to decide definitely. So much of the organic matter as is absorbed by rain falling in the open country is, as a rule, thoroughly oxidized and con- verted into the harmless inorganic nitrogen compound, nitrates, by intermittent nitration through porous surface soils in the presence of air. The nitrates in shallow-well waters, accom- panied by small amounts of albuminoid and free ammonia, indi- cate a high degree of natural purification by intermittent fil- tration and the amount of previous contamination of water by dissolved organic matter. Should the nitrates be accompanied by a considerable amount of unstable albuminoid and free ammonia and nitrites there is evidence of recent contamination. The free ammonia, so called, is in itself harmless, and its presence in sur- face and shallow-well waters is simply indicative of a progressive natural process of purification of water that contains organic matter. "The character of deep-well waters is entirely different. Because of the usual absence of free oxygen in these waters, nitrates once formed by intermittent filtration through well- aerated surface soils may be reduced by contact with mineral salts and organic matter deposited in deep subsoils, the nitrogen reappearing as free ammonia in considerable quantities. Waters of this class may safely contain free ammonia and other nitrogen compounds in quantities which from a chemical view-point would cause suspicion if contained in shallow-well and surface waters. 4 ' The total and relative amounts of the nitrogen compounds in deep-well waters are not, therefore, a quantitative indication of past pollution, as they are in shallow-well waters. The remote- ness of the source of these constituents is in itself a security against dangerous contamination. "A determination of the amount of combined chlorine in waters, particularly surface-waters, is very often valuable in detecting sewage contamination; but in coast countries and in connection with artesian well-waters which may have filtered through soils containing saline matter it loses its significance. "Total solids are largely derived from the mineral matter in GROUND- WATER SUPPLY. 9 solution. The degree in which they will affect water for mechan- ical and manufacturing purposes can be determined by chemical analysis. If contained to the extent of making a water unfit for hygienic purposes the water becomes unpalatable as a rule. ' ' The analysis of many samples of deep-well waters in Eng- land, made under the direction of the 'Rivers Pollution Com- mission on the Domestic Water Supplies of Great Britain,' lead to the following conclusions, namely: 'Of the different varieties of potable waters, the best for dietetic purposes are spring and deep-well waters; they contain the smallest proportion of organic matter, and are almost always bright, sparkling, palatable, and wholesome, while their uniformity of temperature throughout the year renders them cool and refreshing in summer, and pre- vents them from freezing in winter. Such waters are of ines- timable value to communities, and their conservation and utiliza- tion are worthy of the greatest effort of those who have the public health under their charge.' . . . ' In all cases in which spring and deep-well water of good quality are available we recom- mend that they should be employed in preference to surface- or river- water for domestic supply.' " The fear of future contamination of the water-supply from increased population and cultivation of the catchment area is very remote, since the prolonged intermittent filtration which the water receives tends to exhaust or to render harmless the organic matter that may have been originally dissolved, while any organic matter which may have been dissolved from the deep subsoils is probably of a vegetable nature and harm- less. So far as judgment can be based upon a single chemical determination of the nitrogen compounds, it has not detected pollution in any one of the samples of the local deep-well waters which have been analyzed, when considered from the standpoint of deep- well waters. By comparison with other unpolluted deep- well waters, the local waters certainly show a superiority. "Of the three local waters, the Tacquard well is shown by the single determination to be the best." The late Dr. Drown, formerly chemist to the State Board of Health of Massachusetts, furnished a very interesting report I O IV A TER-SUPPLIES. upon the waters of the Galveston wells at a somewhat later date than the report on the preceding pages. It follows in full. REPORT OF DOCTOR T. M. DROWN, OF BOSTON, MASS. " MASSACHUSETTS INSTITUTE OF TECHNOLOGY, BOSTON, MASS., February 6th, 1893. "To the Honorable Board of Commissioners of Water-works of the city of Galveston, Texas. " Gentlemen: I send you herewith the results of my analyses of the samples of water received from you, bearing on the ques- tion of a water-supply for Galveston. " In addition to the sanitary analysis of the waters, I have made a sufficient number of determinations of the mineral ingre- dients to indicate their fitness for domestic and industrial uses. " From the table of analyses it will be seen that the waters from all the Hitchcock wells have a general agreement in com- position. They are characterized by rather high contents of alkaline bicarbonates and chlorides, and low contents of lime and magnesia. The waters should be classed, therefore, as 'alkaline saline.' " I have taken the average of the composition of these five waters as probably representing better the supply obtainable by artesian wells in this locality than the waters from any one well. " i. With regard to the sanitary properties of the Hitchcock waters, the amount of organic matter in the water, as shown by the albuminoid ammonia and oxygen consumed, is extremely small, and as such is of no significance. The free ammonia is a very common ingredient in deep artesian wells. The origin of it is not always easy to explain, but it certainly has no con- nection with recent pollution, the only connection which gives it significance in surface-waters and shallow wells. There is no nitrogen present in the form of nitrites or nitrates. The water may be said, therefore, to be perfectly satisfactory as far as its freedom from organic matter or products of decomposition is concerned. I do not think our knowledge of the effects on the human system of mineral matters, when present in very small amounts in drinking-waters, is at present very extensive or accurate. I know of no instance where the continued use GROUND-WATER SUPPLY. H of water of this character has been followed by injurious results. If we deduct the amount of common salt in the average of the five waters from the total solids, we have 34.43 parts of solid matter remaining, or about twenty grains to the gallon. Assum- ing that these were all sodium carbonate, the amount taken into the system in the regular use of the water would be very small, say seven to eight grains a day. There is no evidence that I know of to indicate that this could prove injurious. "2. With regard to the technical use of these waters, the ad- vantage of softness in water is one that cannot be overestimated. The expense and annoyance involved in the use of hard waters, both in the household and in industrial works, is so great that a water-supply with little lime and magnesia is much to be prized. The most injurious scale-forming ingredient in boilers is sulphate of lime. This is almost entirely absent in these waters, and the lime and magnesia in the form of carbonates is exceptionally small. As is well known, carbonate of soda is added to hard waters as a preventive of scale in boilers. "3. With regard to the permanence in the character of these waters on continued pumping I am not able to form an opinion; time alone can decide this question. From the information given by your engineer, Mr. Kiersted, it seems to me very unlikely that the amount of salt will increase by infiltration from the sea. But new underground areas may be drawn upon which contain water of different character. Thus it will be noticed that sample No. 8, from Tacquard's, contains considerable iron, which is absent, or nearly so, in the other samples. When iron is present in well-water in sufficient quantity to cause a precipitation of iron rust, the water becomes unfit for laundry use. The amount of iron in this water (No. 8), 0.0514 part of oxide of iron in 100,000, is very near the limit of precipitation. Again, both the wells of Tacquard's yield water which is more highly colored than the others, and in both the water is slightly harder. " I do not know whether all these Hitchcock wells have been in continuous use for a sufficient length of time to enable one to say whether the character of the water they now yield is constant. If not, it would seem to be prudent to pump them continuously to their maximum capacity for some weeks to discover if the 12 WA TER-SUPPLIES. . rt H & SI < t -I e > 00 tf 10 SBX9J, 'M 3? '3 jo 3utssoj3 aiqiunj^ IB J9At^j o^upBf UBS 1 ^M 0000 HO 00 g a> >-> M 03 3uiM9jg ipsng ' />0 -snojj ui JJ8M uBisa^jy I " to a n3fj&$>'~ uosuajpiQ J n J UBJS8^tV :-3 : dnoaS jo gSBaaAy i ,. , N OkS.g'2 ,- . J 00 o 00^^00 o to 91JUJ 9UO S9JIU1 |s' 's. "N O^ OvO jo i ! e c^ T3 4J 22 :.s :j ^ : s 'g : ^ iliiiiiiijlj ill|i *-" a; o s 8 eg 5= c^ "S 00 ' J " K P Y .sl rt p" c w J5 :i 00 |*-3 " 5 ^ * Ki f-5| ll S * Sampl well ha nd with dition to t on ignition. GROUND-WATER SUPPLY. 13 water changes in composition, either in the direction of improve- ment or deterioration. Any well yielding water high in iron or with iron continuously increasing should be rejected. " I do not know what system of water- works is under consider- ation, but the effect of the exposure to light and heat of these waters should be considered if open reservoirs are contemplated. The presence of free ammonia in the waters would afford food for the growth of organisms, which might impart unpleasant tastes and odors to the water. " With regard to the other samples examined, the Dickenson well is almost identical with the waters from the Hitchcock wells Nos. i, 6, and 8. The water from Alva is decidedly harder, and therefore much less desirable for general use. The water from Houston is of an entirely different character. It contains much less salt, and its hardness is nearly four times as great as the Hitchcock water. " The water of San Jacinto River would not furnish an accept- able supply without extensive settling-reservoirs and filter-beds, which, in connection with the expense involved of bringing the water sixty miles, would probably be prohibitive. "In conclusion I would say that, in my opinion, the waters from Hitchcock, as represented by samples from the residence of Mr. Tacquard, Wheeler's well, and the railroad well, would in their present condition make a satisfactory water-supply for the city of Galveston from a sanitary, domestic, and industrial point of view." The general superiority of ground-water as a source of public water-supply, hygienically considered, is generally accepted by sanitarians. But how far considerations of quality for hygienic purposes should weigh against considerations of quality for mechanical purposes without prejudice in either direction is somewhat of an open question from other standpoints. As a general proposition, a quality of water which in any particular locality will serve the public and private requirements in a satis- factory degree should prove the most valuable as a commodity, particularly if it be of attractive appearance. A naturally clear, soft, wholesome water is the ideal water. But water of such a quality is accessible to but comparatively few communities. Usually there is a wide departure of the quality 14 WATER-SUPPLIES. of available water from that of ideal water in some one or more of the three named particulars, but as a rule the least variation permissible, popularly considered, is in the clearness of the water. A very slight turbidity will arouse a suspicion in the popular mind, even though the wholesomeness of the water may be unimpaired on account of it, and quickly offend the aesthetic taste. A suspicion of pollution or an offense to the sense of sight becomes all the more intense and aggravated if aroused periodically; that is to say if turbidity is an abnormal condition of a water-supply arising occasionally for a brief interval, a comparison of the con- dition of the water then with a normally clear water is so strik- ing as to magnify and intensify a suspicion of serious pollution. A community will become accustomed more readily to a water somewhat turbid all of the time than to one similarly affected a part of the time. Thus the turbidity occasionally noticed in ground-water drawn from a shallow-water supply gallery parallel with a river and the accompanying increase of bacteria in the water may be due to too high a rate of nitration through the gravel- bed separating the gallery from the river. This changed con- dition of the water-supply becomes at once apparent to every con- sumer, and without knowing the facts the consumers become sus- picious of pollution and are quite likely to suspect a direct intake to the river, accidental or otherwise, to meet some contingency of water service a suspicion affording ground for numerous com- plaints and unpleasant rumors, outspoken complaint of improper management, all of which are a source of annoyance and often of mutual misunderstandings between the water-works management and its patrons. But in any event a judicious water- works manage- ment should desire to avoid either a suspicion of unwholesome- ness or an offense to the senses by serving a uniformly clear water, one of so pleasing and attractive appearance that its use as a commodity becomes popular quite as much as a necessity. There is no desire to be understood as advocating in any measure the clearness of water-supply as a disguise for unwholesomeness. It is mentioned chiefly as a quality which pleases and gives general satisfaction so far as appearances may go, and to this extent, should not be disregarded. While there may be little connection GROUND-WATER SUPPLY. 15 between the qualities of clearness and wholesomeness hygienically considered, still it is known that the provisions which are often necessary to insure clearness often suffice to insure wholesome- ness, as, for instance, the complete removal of sediment from a turbid river-water, or the removal of iron from a heavily mineral- ized ground-water, or microscopic life from a natural lake or reser- voir in fact reflection upon the matter shows that the instances where a clear water is unwholesome are so few as to become notable exceptions wherein individual or community negligence may be a contributing cause. Many recorded instances of dangerously polluted, though clear, well-water lack substantial confirmation of the source of pollution or the avenue through which the pollution reaches the well. It is believed with a host of observed instances to confirm the belief, that the actual source of well-water pollution is, as has been pre- viously stated, through direct overflow of surface drainage or a fissure underflow affording almost as direct communication with the well as the surface overflow. This is stated as a belief for the reason that no matter how well fortified by observation the state- ment may be, it must stand in this day and generation simply as a belief until by confirmation of well-directed scientific proof it becomes recorded as a matter of fact. Exceptional and con- clusively proven cases of well-water pollution can neither be construed fairly as a reason for wholesale condemnation of well- water supply either for private or public purposes, nor be used sincerely as an illustration to cast suspicion on ground-waters as a class. It is seldom that we can gratify our desires with regard to the softness of ground-water, as the character of water partakes largely of the geological structure of the ground in the locality where the water-supply is developed. The highly solvent prop- erty of water renders it capable of retaining dissolved minerals with a tenacity that requires the exercise of something like the force of chemical action to separate them from the water and to reduce them to a condition in which they can be mechanically removed therefrom. The objection to any process of this kind is to be found in the fact that often it may be merely a substitu- tion of one mineral for another or that the expense involved in 1 6 WA TER-SUPPL1ES. the chemical process is either prohibitive or no less than the expense of repairs resulting from the use of a hard water. Prob- ably the expense is the chief objection to the introduction of most water-softening processes. Thus far the softening of water is regarded in sort of a rela- tive way and as possessing scarcely a determining influence in the selection of a public water-supply. It will doubtless be given greater consideration in the future as improved and less expen- sive methods of water-softening are perfected and brought to public notice. Efforts in this direction seem to have been largely confined to the softening of water for industrial use. It is not intended to pursue in detail this subject of the quality of ground-water, as such a course would be somewhat foreign to the purpose of this treatise and would burden the work with much unnecessary matter. As a rule, ground-water derived from a district suitable for water-supply development is hygienically wholesome when proper precautions are observed to avoid contamination through open channels connecting the underground flow directly with the surface flow or run-off. Quantity. The amount of ground-water that is available for water-supply purposes is a perplexing problem to the minds of many a water-works management, as is shown by the many disappointing failures that have attended efforts to secure ground- water supplies. It is believed the problem should not be found so perplexing and uncertain of solution if rationally considered. A few fundamental propositions may perhaps aid in clearing away some of the perplexities. For instance: No more water can be continuously taken out of the ground than goes into it. The yield of the ground-water is dependent upon the character and extent of the catchment area and depth of the saturated water- bearing material. The velocity of flow of ground-water depends upon the character of material through which it must pass in gravitating from a higher to a lower level. The stability of the ground-water supply depends upon the three considerations above stated as well as upon available ground storage at the point selected for developing the water-supply. GROUND-WATER SUPPLY. 17 Were these several considerations kept fully in mind when contemplating the development of shallow-ground water there should be little difficulty in approximating correct conclusions. They possess some variations, however, which it is necessary to consider as we proceed. The amount of water which an artesian basin can furnish permanently is somewhat uncertain because of the difficulty of determining the several governing factors above outlined, and therefore becomes a matter of conjecture except where com- plete geological surveys have been made, which is a work usually undertaken and carried out only by the general government. It is not unusual to find artesian districts which originally sup- ported flowing wells so overtaxed by the exhaustion of accu- mulated water storage as to reduce the water pressure and cor- respondingly the available flow of water to a degree that requires the use of pumping-engines installed at considerable depth below the ground surface to maintain the supply of water. In most instances a reduction of pressure and of flow resulting from constant draft should be anticipated in artesian water-supply development even to the extent of sinking an intake well or installing pumping machinery considerably below the surface of the ground. Interesting measurements were made by Professor William D. Pence of the artesian flow from wells of the Hitchcock group, near Galveston, Texas, for the purpose of determining the flow of water at different elevations between the surface of the ground and the static level assumed by the water in an extension of the well-casing above the ground. The flow of the well ceased at a height of about 30 feet above the surface of the ground. In the following tabulations the heights represent the distance from the top of the 7J-inch well-casing near the surface of the ground upward to the several centers of discharge in a 3-inch rising pipe tapped into a cap screwed onto the well-casing. i8 WATER-SUPPLIES. DISCHARGE OF ARTESIAN WELL AT HITCHCOCK, TEXAS, MAY 19, 1891. MEASUREMENTS TAKEN WITH TWO-INCH EMPIRE METER. Height above top of well-casing. Discharge in gallons per 24 hours. 28.00 feet Scarcely any 25.35 M 8,022 20.45 " 32,089 15-55 40.000 10-62 " 51,343 5-26 70,551 0.76 94,966 DISCHARGE OF ARTESIAN WELL AT HITCHCOCK, TEXAS, JUNE 5, 1891. MEASUREMENTS TAKEN WITH FOUR-INCH CROWN METER. Height above top of well-casing. Discharge in gallons per 24 hours 28.00 feet Scarcely any 20.4 " 28,245 15-21 48,470 10.63 " 67,320 5-39 " 84,374 1.03 " 98,616 It will be observed that the discharge varies almost directly with the pressure or head and that for each one foot of head or equivalent pressure below the level which the water natu- rally assumes in the stand-pipe connected with the well-casing there is an equivalent acceleration of discharge of about 3400 gallons per twenty-four hours; for instance, if the discharge from an orifice in the stand-pipe one foot below the static level of water therein is 3400 gallons, then the discharge 50 feet below said level should be 170,000 gallons per day or 340,000 gallons at a level 100 feet below said level. The experience with artesian wells at Memphis indicates a discharge of about 1,000,000 gallons per day from fifty wells for each 4 feet of draft, or a rate of increase of about 5000 gal- lons per twenty-four hours per well for each one foot of draft. GROUND-WATER SUPPLY. 19 It is estimated that the available flow from a single pumping- station of the Memphis district is about 25,000,000 gallons per day under a draft about 60 feet below static water-level. In the Hitchcock district, where the available draft is about 50 feet, the station yield should approximate about 15,000,000 gallons per twenty-four hours. But the water-supply develop- ment need not be confined to a single pumping-station and its group of wells, as in an extensive artesian district auxiliary sta- tions and other groups of wells may be located beyond the zone of influence of the first group possibly several miles therefrom as local conditions suggest and operated by power transmitted from the original or central station. Artesian water-supplies, particularly those derived from sand or sand rock, are exceedingly desirable and should be developed to the highest possible degree and with the greatest amount of care. They can scarcely be equalled by any artificially filtered surface-water supply, considered hygienically. Shallow ground-water supplies are usually developed from sand and gravel deposits in the valleys of creeks and rivers. In a valley where the stream flows over a rock bed the sand deposits are thin and usually so exhaustively drained as to afford but a very small yield of water. The attempts to develop a public water-supply in valleys of this character have failed almost with- out exception, for there is no permanent water storage of any great volume. Valleys like those of the important rivers of the central states often possess immense deposits of sand and gravel extending 50 or more feet below the river-beds. These deposits afford immense reservoirs for the permanent storage of water, which can be drawn upon for large volumes of water year after year with no fear of depletion. The valleys of the Mississippi and Missouri Rivers afford a striking example of sand deposits of this kind, but, strange as it may seem, the value of these deposits as sources of water-supply has as yet never received in practice the public appreciation they deserve. The impression seems to prevail in communities located along these rivers that the rivers 2 o WA TER-SUPPLIES. themselves are the best available source of supply, and immense sums of money have been expended in the erection of water puri- fication works without a thought apparently of considering the availability of a clear and wholesome supply from the sand beds beneath the rivers. Any impression that the deposits are generally a mixture of alluvia and quicksand, materials which are known to be altogether too fine for the free flow of water, is erroneous. While deposits of this character may be encountered above the level of the river- bed, it is generally true that the deeper deposits below the bed of the river are composed very largely of clean coarse sand inter- mingled with gravel. Frequently the coarse sand is in strata separated by thin layers of tenacious clay. In some districts along the Mississippi River the deeper deposits for 20 to 30 feet are composed largely of heavy gravel and sand, with scarcely a suggestion of the presence of quicksand. The heavy and coarse deposits can be made to yield a large supply of water by proper methods of development. In estimating the available yield of water from sand deposits of these and similar river valleys the matter of catchment area is scarcely to be taken into consideration outside the valley proper, for the river is an important factor in keeping the sand deposits supplied with water should they be drawn upon. The situation in this regard can probably be more clearly presented by referring to tests made for the purpose of developing the water-supply conditions in the valley of each of the two rivers named. In 1902 a study was commenced of the ground-water-supply conditions of the Mississippi River valley at a point about two and one-half miles below the city of Muscatine, Iowa, having in view the new water-supply works for that city. The studies finally resulted in a decision to abandon the Mississippi River, the source of supply for twenty-five years of the original water-works, and to develop ground-water at the site of tests referred to. They also developed much interesting information regarding ground- water conditions. Fig. i is a diagram of a series of test wells excavated to bed- rock or clay on a line about right angles with the Mississippi River. GROUND-WATER SUPPLY. 21 Each well after reaching the rock or clay substratum was with- drawn a few feet to admit of free percolation of water into it, except well i, which had a strainer about 8 feet long composed of three rings of vertical slots, nine slots to each ring, J- to f of an inch wide and respectively 2iJ, 24 J, and 33 J- inches long, each ring of slots being separated by 8 or 10 inches of solid metal. The combined area of the slots was about four and one-half times the sec- tional area of the 8-inch well-casing. The strainer is the design of William Molis, superintendent of water-works, Muscatine, Iowa. FIG. i. Muscatine Island (island in name only), where the test was conducted, is several miles wide, with a slightly undulating sur- face. A high- water slough skirts the bluffs on the western side and the Mississippi River washes the eastern side of the island. The rainfall upon the island, which is not evaporated or absorbed by vegetation, passes almost entirely into the underflow; scarcely any of it disappears in surface run-off. This land is under cultivation for the raising of garden truck and accordingly extensively fertilized. Storm- water rapidly dis appears, showing thorough under drainage. Plate I gives an idea of the geological structure of the island, at least for 3000 feet inland, and shows a vertical section along the line of test-wells and soundings of the Mississippi River to the Illinois shore. It also serves to show the immense permanent storage capacity of the gravel deposits below the low-water stage of the river, and the additional temporary storage between the low- water and the usual high- water marks. The tangible value of even the temporary storage is not to be underestimated along such rivers as the Mississippi and Missouri, for as we write the Mississippi River has been 5 feet or more above low water for nearly a year, w i vtroTOia 6-s IPM. GROUND-WATER SUPPLY. 23 and accordingly has served to maintain a high ground-water level. However the temporary storage is not an element that can be depended upon for water-supply year in and year out, for during the period between 1878 and 1902 there were ten years when the average gauge-reading of the Mississippi River at Muscatine was below the 5-foot stage and two years when the stage of the river was below the 5-foot mark for the entire year. The problems which were presented for solution in the Muscatine study of ground-water supply are the same as those presented in other similar localities, and the methods there pursued are char- acteristic of those which may be pursued elsewhere with such variations as may suit local requirements. In general the essen- tial problems for solution are as follows: 1. What is the extent and available depth of the permanent ground-water storage? 2. What is the available velocity of flow through the deposits of sand and gravel underlying the river valley and the probable greatest permissible hydraulic slope? 3. What is the source from which the gravel-beds are supplied with water and how much of the water thus supplied is avail- able for use? 4. What is the chemical and bacteriological condition of the ground- water? 5. Is there danger of contamination of the underflow from drainage of the city above or from farms in the immediate vicin- ity of the site of the tests and observations? 6. What extent of water-supply development work is required for the desired supply of water ? The borings were made for only a distance of 3000 feet from the river, affording information of a practically uniform geological formation of the lower strata of water-bearing material. Private wells for a radius of a mile or more from the site of the tests, equipped with centrifugal pumps, showed the water-bearing ma- terial to continue much beyond the range of the test-wells. So far as could be ascertained the bed of the Mississippi River is of the same formation, and it was assumed "the gravel formation extended even beyond the Illinois side of the river. Therefore without pursuing investigations to actually determine the full 24 WATER-SUPPLIES. extent of the gravel deposits, a work evidently involving large expense, reasonable assurance was developed to indicate at least two square miles of available catchment area which should absorb sufficient rainfall^ if rainfall only could be relied upon to support the gravel-beds, to yield at least 454,000 gallons of water per square mile of catchment area, or an average of 813,500 gallons per twenty-four hours, the smaller computation being based upon gj- inches or 35 per cent of the minimum annual rainfall, and the larger amount being based upon 15 inches or 45 per cent of the average rainfall. The local conditions seemed to require a basement level of the pump-pits at about 6 feet above low water, and the pump- plunger about 9 or 10 feet above low water, and a suction draft to a level 10 feet below low water or possibly a little more. With due allowance for hydraulic slope of the ground-water the available permanent storage which can be drawn upon in ad- dition to the rainfall yield is computed at 130,000,000 gallons per square mile. During the months of September and October, 1902, prac- tically simultaneous observations were made of the level of the water in the nine test-wells and of the river. The stage of the river was practically constant for the month preceding the beginning of the observations. The period covered by the obser- vations embrace a period of rather rapid rise of the river and a corresponding fluctuation of the ground-water level in all of the test-wells. The fourteen representative series of water-level observa- tions are represented in the diagram, Plate II. Other observa- tions were made between September 21 and 26, in connection with a pumping test, which are the subject of special comment further on. The four water-surface lines of September 6 to 13, inclusive, show a pronounced slope of the ground-water table towards the river of an average of 0.8 of a foot in 1000 feet and necessarily a movement of the absorbed rainfall from remote points of the island towards the river. A rise of 2 feet in the river between September 13 and 21 produced a corresponding but gradually decreasing rise inland, (O CS OO I C7 10 ' .TiTiTiTiTiT.iT.TiTn 111 2 6 WA TER-SUPPLIES. even further inland than well 9, where the recorded rise was 0.3 of a foot. The average slope of the ground- water table between the dates named is about 6 inches per 1000 feet. It is observed that during this interval of progressive rise the slope remains downward towards the river, showing a persistency of the ground-water to advance in that direction notwithstanding the check imposed by the rise of the river. This check or damming of the ground-water at the river-front compelled the advancing underflow to fill the voids of the sand in the wedge between the water planes of September 13 and 21. In order to accomplish the filling of this wedge 2 feet in height at the river-front and with an apex about 3300 feet inland, the water in the saturated gravel of the island down to the clay substratum, a depth of about 43.5 feet, must have advanced laterally at least 58 feet through the gravel or at the rate of 7.25 feet per day, or nearly the equivalent of 2J- feet of solid water 43.5 feet high after making correction for a rainfall of ij inches during the interval. As the river continued to rise the slope of the ground-water was reversed to an inclination from the river inland about Sep- tember 23, and continued reversed until after the summit of the rise was reached on September 30. The average inclination of the slope inland during this period was 1.13 feet per 1000 feet. The advance of river-water inland to fill the voids in the sand between the curves of the dates named is computed in a manner similar to the above computation to have been 41.1 or at the rate of 13.7 feet per day, equivalent to 4.6 feet of solid water 44 feet high. In the foregoing computation a void space of one-quarter the mass was allowed for the wedge embraced between the several ground-water planes in order to allow for moisture permanently retained by capillary attraction, and one-third the mass was considered as available void space in computing lateral sectional flow through saturated material. The matter may be put into convenient shape for compu- tation by means of the Darcy formula, namely, v=ki y GROUND-WATER SUPPLY, 27 wherein v = velocity in feet per day; i = inclination of ground-water surface in a given dis- tance divided by that distance; .&=a factor depending upon the porosity of material through which the underflow passes. Interval. V. Velocity in feet per day of solid water. *. Inclination. k. Factor. Septem <( 3er 1 3 to 2 1 2-5 i-55 4-63 0.0005 o. 000272 o. ooi 13 5000 5700 4100 20 to 21 27 to 30 Average value of k is 4900 in round numbers In order to obtain the actual advance as measured in the voids of the sand the tabulated velocities should be multiplied by 3 and the corresponding average value of k would then be 14,700. During the interval between the. dates September 21 and 27 the condition of the ground-water table was observed in the several wells while pumping on one of the wells was in progress. Plate III contains a diagram showing the fluctuations referred to. A centrifugal pump was connected directly with the 8-inch casing of No. i well, the details of which well are described on a previous page, and operated practically continuously by means of a belted connection with a traction-engine, from 7 A.M. of the 2ist to 12 P.M. of the 26th, one hundred and twenty-five and one-half hours. The object of this test was for the pur- pose of deriving information regarding the porosity of the gravel deposits. Accordingly the actual amount of water pumped from the well was regarded as purely an incidental matter and of itself capable of furnishing little or no reliable information of the kind desired. Such approximate measurements as were made of the discharge of the pump as the water passed through a wooden flume to the river indicate a discharge at the rate of 1,500,000 gallons per twenty-four hours. An interesting fact connected with the test is the one that the river rose over 3 feet between the morning of the 2ist and the 26th and that a corresponding rise was observed in most mnnTT ' nrmn \ \ \ -Well No.9 Well No. 8 Well No.7 Well No. Well No.5 Well No.4 Well No.3 Well No.2 Well Nb.l GROUND- WATER SUPPLY. 29 of the wells notwithstanding the large amount of water that was abstracted from well No. i. Plate III shows the zone affected by the pumping to extend about 700 feet from the pu^ip well and to present a face about 1400 feet in diameter to the river-front. The depth to the clay substratum below the water-table at this well is about 45 feet. When pumping ceased at 12.25 P.M. the zone of depleted sand as the result of pumping was about 1000 feet in diameter. Between that hour and 4.30 P.M. of the same day the inflow from the river so filled the depleted sand that there was a con- tinuous slope to test- well 8 and almost a level water-table for the next 1500 feet inland, or to test-well 9. On the morning of September 27 the influence of the rising water-table caused by inflow of water from the river became decidedly apparent at and beyond test-well 8, and were it not for the heavy pump- ing of the preceding days the water-table would doubtless have presented a more uniform slope. As soon as pumping ceased the inflow of water was comparatively heavy and must have been influenced very largely by the steep slope which then obtained between the river-front and pump well No. I even as late as the morning of the 27th. The average slope between 12.25 P.M. of September 26 and 7 A.M. of the 27th was 2.8 feet per 1000 feet, and the estimated volume of the cone of depleted sand of a base 1000 feet in diameter which was filled with water between 12.25 and 4.30 P.M. and of the wedge between the water-table of the last stated hour of the 26th and that of the morning of the 27th divided by 48,000 square feet of river frontage gives approximately a velocity of flow through the sand of 45 feet per twenty-four hours or about 15 feet of solid water. From these data we compute by the formula v=ki the value of the coefficient of porosity (k) to be 5360. A previous method of computation gave the value of k at 6200, but it is believed the later computation fits the observations more correctly. In view of these computations a factor of porosity 4000 to 5000 appears to suit the Muscatine conditions and admits of the following local rule, namely: Multiply the observed slope of the ground-water table expressed in feet per 1000 feet by the factor 4 to 5 to get velocity of underflow WA TER-SUPPUES. expressed as solid water, or 12 to 15 to get velocity expressed as lateral movement through sand, assuming the voids in sand to be one-third the mass. No mechanical analysis was made of the Muscatine gravels and sands at the time of the tests referred to, but later when excavating for a permanent water-supply well, several samples of the sand and gravel penetrated by the boring were collected and analyzed, with the following result. MECHANICAL ANALYSES OF MUSCATINE SAND AND GRAVEL. Number of sieve. Per cent of sand finer than stated sieve numbers. i. 2. 3- 4- Rejected by 6. ... 6 I O 5-5 94.2 83-1 63-3 44.0 i . i 0.09 0. OO 18.5 80. 50 58.08 41 o 32.4 24. 1 2.3 35 o.oo 54-5 45 5 27 2 I l'.l 62 2 O .2 36.8 63.2 25-8 7-6 3- O . 2 , 02 1 4 18 20 . . 40 60 So In order to form some conception of the classification of the Muscatine sand we have deduced the value of the coefficient of porosity (k) of assorted and washed sands of various sizes from the tabulated results of experiments contained on pages 210, 21 1, and 244 of Professor F. H. King's report in the Nineteenth Annual Report of the Geological Survey. The factors in the following table indicate that the effective size of the Muscatine sand should be about the grade of a coarse concrete sand, the nearest tabulated size of sand being 0.7146 millimeter, which is little less than one thirty-second of an inch or somewhere near the size of sand which will pass a sieve of 20 meshes to the lineal inch and will be retained by one of 40 meshes to the lineal inch. However, the analysis of the Muscatine sand indicates a coarser grade of sand, at least samples 3 and 4, than that indicated by the table, a circumstance due no doubt to the fact that the sand experimented with by Professor King was of uniform sized grains, possessing a uniformity coefficient of unity, while the Muscatine sand is an unassorted sand of various sized GROUND-WATER SUPPLY. 3 1 grains. It should be recollected that the velocities stated in the following table are measured as volume of solid water passing in a unit of time, and that for a lateral velocity in the voids of the sand the tabulated velocities should be multiplied by about 3. FLOW OF WATER THROUGH SANDS AND SANDSTONES IN CUBIC FEET PER MINUTE PER SQUARE FOOT OF SECTION UNDER A PRESSURE GRADIENT OF I IN 10. Series Number of sand . Size of sand grains in millimeter. Flow in cxibic feet per minute. * Velocity in feet per 24 hours. Grad. i in 10. * Value of coefficient (). ^o. 8 quartz 2 . 54 5.2268 7 $26 . 6 7^266 7 I. 808 3- 6 49 / o 5254.6 / J 52546 6 I-45 1 1.8481 2161.3 21613 Si 1.217 1.3582 1955-8 19558 5 1.095 1.2232 1761.4 17614 4 0.9149 0.8242 1186.8 11868 3 0.7988 0.5084 732.1 7321 2 0.7146 0'3 2 95 470.9 4709 I o . 6006 0.2321 334-2 3342 o . 5169 0.1767 254.4 2544 IOO o. 1018 o. 0041 5-9 59 Dunville sandstone. 0.0363 0.029 -3 3 Madison sandstone . 0.0818 o. 246 2-5 2 5 * Author's Computation. In this connection it is interesting to know what the coefficient of porosity may be of natural sands and gravels. Apropos of this part of our subject are the experiments of the Metropolitan Water and Sewerage Board of Boston, Massachusetts, conducted to determine the rate of percolation through sand and soils, sum- marized by F. P. Stearns, chief engineer of that Board, as follows: "Amount of filtration in gallons per day through an area of 10,000 sq. ft. of different materials, with the loss of head of i foot in 10 feet. "Coarse sand, the average of three experiments. . . 2,200,000 Medium " " six 400,000 Fine " " two " 90,000 Very fine " " " " " " 7,200 Soil " " " " " 510" The mechanical analysis of the several grades of material above described is not given in the article referred to, but the data are sufficient for the computation of the velocity stated in terms of solid water and the coefficient of porosity as follows: 32 WATER-SUPPLIES. Velocity. Coefficient (). Coarse sand 29.3 293 . o Medium sand 5.3 53.0 Fine sand 1.2 12.0 Very fine sand o . 96 9.6 Soil 0.0068 0.068 It is seen that the grade of sand has much to do with the per- missible velocity of water flowing through it; that is to say, the coarser the sand and the more uniform the size of the individual grains of sand the more freely does water flow through it. As a rule, however, a sand deposit is a heterogeneous mixture of inter- mingled large- and small-sized grains. If the small grains are very fine and constitute a considerable percentage of the total volume, the voids of the deposit may be so thoroughly filled as to admit of but slow percolation, notwithstanding the presence of even a considerable amount of coarse gravel. Instances of this kind are not uncommon. A striking example of this kind is to be found in the following mechanical analysis of a sand from a district bordering on the Ohio River. Sand rejected by sieve No. 6 36 per cent. " passed " " " 6 64 " " " " IO ........... c* " " " " " 14 ........... 53.3 " " a ti n u it - u " " " " " 20 ........... 49.2 " " " " " " " 40 ........... 34.7 " " " " " 60 ........... 20.0 " " " " " " " 80 ........... 16.5 " " " " " ioo ........... 12.7 " " The 12.7 per cent of the sand which passed the No. ioo sieve contained a considerable amount of silt which by washing and re weighing was found to be about 2|- per cent. The uniformity coefficient is about 12, indicating a heteroge- neous mixture of gravel stones of considerable size with a highly assorted sand in which there is a large percentage of fine grains. The result of Allen Hazen's investigations under the direction of the Board of Health of Massachussetts indicates that the finer 10 per cent, of the sand grains controls the percolating capacity GROUND-WATER SUPPLY. 33 of sand and gravel, and suggests expressing sand texture in terms of a "uniformity coefficient," found by dividing the size of the sand grain separating the coarser 40 per cent from the finer 60 per cent by the size of the grain separating the finer 10 per cent from the coarser 90 per cent. It seems, however, as though the entire relation of sand texture might be more conveniently expressed by a nomenclature referring to a series of graduated sieves and the uniformity coefficient ex- pressed as the ratio between the number of meshes to the lineal inch of the sieve separating the coarser 90 per cent from the finer 10 per cent and the number of meshes to the lineal inch of the sieve separating the finer 60 per cent from the coarser 40 per cent. The author suggests a nest of sieves for the purpose of analysis graduated 100, 80, 60, 50, 40, 30, 20, 18, 10, and 6 inches respec- tively to the lineal inch. The size of the wire entering into the construction of the sieves must necessarily vary in gauge and should be fixed in accordance with some practical standard. Having once arrived at a standard nest of sieves the sand can be classified as No. so and so, corresponding to the sieve which allows it to pass after a definite period of agitation of the sieves nested. Thus a sand which passes a No. 6 sieve and is retained by a No. 10 sieve, or the next size finer whatever it may be, would be classi- fied as No. 6, etc. To illustrate the method reference is made to a table repre- senting a mechanical analysis of sand from a series of borings in the valley of the Misssouri River shown graphically on Plate IV. ANALYSES OF MISSOURI RIVER SANDS. No. of sieve. Per cent of sand finer than stated sieve number. Well No. i. Well No. 2. Well No. 5. Well No. 6. Missouri River channel. Quicksand. Rejected. . 6 3-7 96.93 91-93 85-97 80.23 73- 12 24. 12 6.87 4-OI 2.16 9-34 90.66 80.63 72.24 64.70 55-70 !7-3 2 7.81 5-60 3-52 20.82 79.18 64.05 49.14 37-89 27 . 10 3.87 1.26 0.91 0.68 O.O IOO.OO 99.42 98.82 98.20 97.07 75.27 17.81 9-34 4-94 5-94 94.06 87.25 80.13 73-48 65-95 29.07 12 .07 8.44 5-69 IOO.OO 96.17 85.46 65-54 40.92 10 id. 18 20 40 60 80 loo Borings along the Missouri River near Fort Leavenworth. 34 GROUND-WATER SUPPLY. 35 Upon platting the percentages corresponding to the above- stated sieve sizes and connecting the consecutive points so platted the sieve number may be read off corresponding to the effec- tive size of the sand, or that which separates the finer 10 per cent from the coarser 90 per cent, also the sieve number correspond- ing to the separation of the finer 60 per cent from the coarser 40 per cent. Dividing the former by the latter gives the uniformity coefficient. The following table expresses the results of the platting of the preceding table. No. of test-well. Sieve corresponding to the separation of Uniformity coefficient. Approximate effective size in millimeter. Finer 10% from the coarser 90%. Finer 60% from the coarser 40%. I 54-5 56 .0 34-5 79.0 72.0 25.2 19 .O "5 45-5 23-5 2 . 12 2-95 3-00 1-74 3-07 0.36 o-35 o-55 0.21 o. 29 2 c . 6 Missouri River. . . . In order to show the relation between the sieve number and the effective size of the sand grain, the tabulated results of Allen Hazen's experiments in the mechanical analysis of sands con- tained in the Twenty-fourth Report of the State Board of Health of Massachusetts have been platted, and from the diagram so constructed there has been tabulated the relation above referred to over as wide a range as it is necessary to consider in practice. The table follows. TABLE SHOWING THE RELATION BETWEEN THE SIEVE NUMBER AND THE EFFECTIVE SIZE OF SAND GRAINS. Sieve No. Effective size in millimeter. Sieve No. Effective size in millimeter. 140 0-135 40 0.46 120 100 90 0-155 0.18 o. 20 3 20 18 0.71 o. 96 I . IO 80 O. 22 14 1-52 70 60 0.24 0.32 10 6 2.04 3-9 50 o-39 3 6 WATER-SUPPLIES. The essential advantage to be derived in a classification of sand by the sieve number is that that nomenclature is more gen- erally understood and is in close association with the only appa- ratus that is usually available in field operations of the mechanical analysis of sand. The method may be carried a step farther and a series of factors deduced by which the measured slope of the ground-water table may be multiplied to give the velocity of underflow and furthermore these factors may be tabulated in conjunction with corresponding sieve numbers in a manner to facilitate the work of computation. There has been already given a series of such factors (k) in formula v =ki in the table expressing the results of Professor King's experiments on page 31. However, these factors repre- senting the condition of minimum resistance offered by sand to the flow of water are not generally applicable, for the reason that they represent a measure of the resistance of sorted sands of uniform grain possessing a uniformity coefficient of unity which is a condition of material not encountered in field oper- ations. Allen Hazen gives a formula for the flow of water through unassorted sands as follows: *Fahr.+io 60 \ )' where v is the velocity of water in meters daily in a solid column of water of the same area as that of the sand, c is a constant factor which present experiments indicate to be approximately 1000, d is the effective size of sand gains in millimeters, h is the loss of head, / is the thickness of sand through which water passes, t is the temperature (Fahr.)- Assume a temperature t of 50 degrees, which is approximately the temperature of ground-water, and that the entire head or pressure of water for a depth equal to the thickness of sand is consumed in producing velocity, as would be the case of ver- GROUND- WATER SUPPLY. 37 tical flow with unobstructed discharge in a layer of sand satu- rated to the top, then Hazen's formula reduces to the simple expression v =cd 2 , the factors cd 2 being equivalent to k for ver- tical flow in the Darcy formula previously described. Upon using the values of effective size for which the corre- sponding sieve numbers are known, as given on page 35, and interpolating for intermediate sieve numbers, we have the results expressed in the following table. VALUES OF COEFFICIENT OF RESISTANCE k IN FORMULA v = ki, COR- RESPONDING TO STATED SIEVE NUMBERS. No. of sieve. k No. of sieve. k No. of sieve. k 6 49889 24 2474 60 336 8 3!77 26 22OO 70 189 10 13650 28 1926 80 159 12 10614 3 1653 90 131 14 7578 32 1461 IOO 106 16 5773 34 1269 I2O 79 18 3969 36 1077 I4O 60 20 3022 40 694 2OO 40 22 2748 50 499 EXAMPLE. The velocity of flow through a sand 90 per cent of which by weight is retained by a No. 60 sieve when the ground- water slope is i foot in 1000 feet is v =336x1/1000 =0.336 feet per day of solid water or i foot per day in terms of the voids in the sand. EXAMPLE. What is the grade of the sand which with a slope of i foot in 100 feet admits of a velocity of 10 feet per day in terms of void space? In this case =k or k =333, correspond- ing to a number 60 sand in preceding table. A recent experiment to determine the flow of water through a No. 55 sand resulted in a measured vertical velocity of flow of 511 feet of a solid column of water when the water covered the sand to a depth of 14^ inches and a corresponding value of k of 425 for sand just covered with water, the uniformity coefficient being 2.1. Upon platting the results of the analysis of the Musca- tine sand as tabulated on page 30 the following table is de- rived. 38 WATER-SUPPLIES. EFFECTIVE SIZE AND UNIFORMITY COEFFICIENT OF MUSCATINE SANDS. Sample. Sieve corresponding to the separation of Uniformity coefficient. Approximate effective size in millimeters. Finer 10% from Finer 60% from coarser 90%. coarser 40%. I 32.0 15- 2 . I 0.81 2 33- 9-5 3-5 0.86 3 17.0 I . 20 4 13-5 6.25 2.0 i-59 Now it will be remembered that the value of k in the for- mula v = ki as found by computation based upon water-level measurements was 4900 for velocity in terms of a solid column of water. The same factor k computed from the table of coefficients on page 37 for the sieve numbers 32, 33, 17, and 13.5 is respectively 1461, 1365, 4871, and 8337, or an average of 4008 without regard to the respective depths of the several grades of water-bearing sand, which information just at present is not available, but which when definitely known will doubtless modify somewhat this value of k. Serviceable water-bearing sands are seldom finer than No. 70, and usually of a range of 60 to 30. Deep beds of water-bear- ing gravel and sand like the Muscatine deposits are rather excep- tional. The water-bearing capacity of a sand is an essential con- sideration in judging of its value for water-supply purposes, for unless it is of a grade which will admit of a free circulation of water the results of water-supply development may be very disappointing. Wherever the natural velocity of underflow and the slope of water-table can be measured with a reasonable degree of approximation, it is best to take these measurements, as they offer direct evidence of the flow through the sand deposits. But such measurements are not always feasible and usually some substitute must be accepted. The best substitute is that of a careful mechanical analysis and a survey of the sand deposit of sufficient extent to admit of capacity determination of the character herein described. Direct pumping from a well seldom furnishes reliable evi- dence of the permanent supplying capacity of sand deposits GROUND-WATER SUPPLY. 39 unless continued for a long period of time, much longer in fact than is afforded most investigators of water-supplies. The results determined by pumping are usually in excess of the per- manent yield by the amount of water contributed to the well from local storage. For instance, if one were to attempt to determine the flow of water into a pond by pumping from the pond, it is evident that so long as the level of the water was depressed as the result of pumping, a draft is made upon storage and the volume of water delivered by the pumps is in excess of the actual inflow and will continue to be in excess until the level of the pond ceases to fall or the storage is completely ex- hausted. The same principle holds true in pumping from a well. The storage in the sand about the well augments the yield of the well and will continue to do so until exhausted and a stable water-table is established in the sand deposit. How- ever a long period of time is sometimes required to estab- lish a stable water-table for the reason that available storage extends a considerable distance from the well and gives up its water in a progressively decreasing volume moving at a low velocity. A short- time pumping test furnishes direct information of value when observations are made of the curve assumed by the water in the ground approaching the well. A steep or abrupt pitch downward toward the water surface in the well over a com- paratively restricted circumscribing area indicates a fine sand of high resistance, while a flatter pitch covering a more extensive area affords information of the presence of a coarse sand of com- paratively low resistance. It is apparent therefore that for a given rate of yield a fine sand deposit must be much deeper theoretically than a similar deposit of coarse sand. There are records of cases where the depletion of ground storage as the result of continuous draft has been so gradual as to extend over a period of several years, showing conclusively the erroneous conception which usually arises from the results of short-period pumping tests. A tunnel driven under a mountain will often open subter- ranean fissures from which water flows into the tunnel in great volumes for a considerable period of time and finally dwindles 40 WATER-SUPPLIES. down to a comparatively insignificant flow. Other instances of a similar character are encountered when shafts have been sunk into water bearing sand rock and tunnels driven laterally for a considerable distance. At first water flows abundantly, but as the draft continues and the water pressure falls as the natural storage is depleted, the flow diminishes and finally must be re- duced to the annual rainfall supply. Similar experience has fol- lowed the use of filter galleries in sand and gravel deposits all going to show that a study of the mechanical make-up, depth and extent of water-bearing deposits, as well as available ground- water slope, constitute essential elements of study in formulating correct conclusions with regard to the probable permanent yielding capacity. These observations have their exceptions, as, for instance, when water is taken from a well penetrating the permanent storage deposits underlying such rivers as the Missouri and Mississippi, hereinbefore alluded to; for then the influence of the river has a pronounced effect in restoring rapidly the depleted storage resulting from a heavy draft upon ground- water. The Muscatine studies afford a striking example of river influence as shown by the diagram representing the result of these studies. It is seen that under normal conditions there is a pro- nounced slope and flow of ground-water towards the river, and it is obvious that the inclination of the ground-water table riverward must be modified both by a departure of rainfall from the normal and by river fluctuation, with a tendency to flatten during a drought and a prolonged stable stage of the river. It is also clear that a rapid rise of the river dams the ground-water, checks its advance towards the river, and by back pressure causes the water to rise vertically in the ground for a long distance back from the river, thereby reducing the inclination of the water-table and finally reversing the slope should the rise continue. During the exist- ence of reversed slope of the water-table, water from the river forces itself into the gravel-beds and drives back the ground-water in a retreating wave. Thus retreating and advancing waves of ground-water, gradually tailing out as they advance inland, beat time to the fluctuation of the river. Certainly the influence of rivers upon storage of water in the ground is pronounced, and is a factor of support which can be depended upon in years of abnor- GROUND-WATER SUPPLY. 41 mally low rainfall so long as the gravel deposits extend well below the river-bed and afford permanent storage. Whatever support such deposits of gravel receive from the river naturally may be expected to operate when artificial con- ditions are created by drawing water from the ground storage reservoirs to whatever depth may be found practicable. The river inflow to restore depleted storage is pronounced and effec- tive and proportionately eliminates the necessity of considering extensively the catchment area and the amount of rainfall. The velocity of flow of such rivers as the two referred to is sufficient to prevent a silting of the bed of the river, inasmuch as it is naturally much in excess of any percolating velocity which can originate in the passage of river-water downward through its bed to supply any near-by artificially depleted storage. Sluggish and muddy streams may accumulate a layer of silt over the bed which at ordinary stages of water interferes with replenishment of depleted storage in neighboring deposits by in- flow from the stream. In such instances the basis of computa- tion of available yield must be based largely upon absorbed rain- fall. Likewise the basis of computations for the sand and gravel deposits often encountered in territory bordering the coast must be the absorbed rainfall. Thus it is found in these instances that a mechanical analysis of the water-bearing material, its depth and extent, the natural slope of the water-table and the velocity of underflow, are im- portant factors for the determination of permanent yielding capacity. The slopes of the water-table and accordingly the velocity of underflow will be found to possess seasonal and period- ical variations, often compelling a draft upon storage for a con- siderable period of time to furnish the desired yield. It is im- portant to determine the probable extent to which natural storage may be thus drawn upon without permanently depleting it; that is to say, without exceeding the replenishing capacity of the rain- fall during the wetter periods. The dry- weather flow of streams is an index of the volume of underflow, and therefore a careful gauging of those streams which drain a limited territory affords information of the rainfall-absorb- ing characteristics and yielding capacity of restricted areas. 42 WATER-SUPPLIES. Such studies are best adapted on a limited scale to streams draining comparatively small catchment areas through which the meteorological conditions are generally the same. However when facilities admit of extensive observation a measurement of the increment by which the flow of a stream progressively increases, affords information of the volume of underflow entering even large streams draining extensive territory. A hydrological survey of territories and districts with a view of determining underground run-off of rainfall is a question which has engaged the attention of but few communities in this country. Therefore when a specialist is called upon to give advice with regard to the feasibility of a ground-water supply, there is usually a dearth of information, except that of a very general character, often confined solely to rainfall statistics collected by the meteoro- logical department of the general government. The gauging of streams and other necessary accompanying measurements or observations in order to secure complete data of the locality is a matter which usually cannot be undertaken in the limited time available when a project for water- works is first carried out, and as a rule the first steps are usually guided by and based upon an analysis of such general information as can be gathered, to- gether with the facts and data bearing upon the subject which may have been collected elsewhere. The experience of com- munities with ground-water supplies is often very disappointing perhaps no more so with ground-water than with other sources of water-supply but nevertheless serious and tangible enough to affect the interest of the entire community and to arouse doubts of the expediency of making further efforts of improvement along the line heretofore pursued. A systematic water- works and water- supply record maintained from year to year showing in detail the technical history of the water-supply plant would serve greatly in solving many perplexing local problems. Unfortunately such records are not always available, and frequently after years of experience only meager general information is still all that is available to guide in an improvement of the water-supply works. However, where detailed information is lacking, it is always profitable to supply its place by such well-directed tests and observations as time and facilities may admit. The nature of GROUND-WATER SUPPLY. 43 some of the detailed information that is desirable and which can be acquired by comparatively inexpensive tests has been already pointed out. But in addition to this information a sanitary sur- vey of the site of a proposed ground-water supply should be made to determine both the area and physical make-up of the catch- ment basin, particularly when the balancing effect of a near-by large river upon the ground- water storage is not available. In this case rainfall must be the sole reliance of a ground-water supply. The soil in the catchment basin which collects the rainfall must be porous enough to absorb a considerable percentage of the water and the geological substructure of a character which admits of the necessary free lateral movement of the ground- water towards the site selected for developing the water-supply. There is a wide difference in absorbing capacity of the soils and sands, a difference which is well exemplified in the experi- ments of Stearns, before alluded to on a previous page of this chapter. Upon tabulating the results of these experiments in a manner to show the rate of vertical percolation (which is about ten times the rate determined by the experiments at a grade of i in 10 ) some idea may be formed of the relative porosity of sand and soils. PERCOLATING CAPACITY OF SOILS. Material. Rate of vertical absorption in feet per day. Ratio of absorption. Coarse sand 2Q3 . 3 4? 14 Medium sand ZT. . "2 784 Fine sand 12 .O 176 Very fine sand Soil o. 96 0.068 14 I The results of another experiment by Professor King to de- termine the rate of percolation through a sandy soil covered with a yellowish sand are given in the table on page 44. We must remember, however, that the laboratory experiments to determine the rate of percolation through unassorted sand and soils do not take into consideration the modifying effects of natural conditions such as frost action, vegetable growth, the intermittent and variable intensity of the application of water 44 WATER-SUPPLIES. which occurs naturally through the rainfall; in both these experi- ments the water was fed continuously to the material experi- mented with. Relatively the experiments are valuable sugges- tions and seem to show that a collecting area which is desirable for the absorption of rainfall should be of a sandy texture. The close-grained soils where clay generally predominates are con- trolled largely by the laws of capillarity and admit of but an exceeding slow rate of percolation. PERCOLATING CAPACITY OF SOILS. Section of pit. Effective size of soil grains in millimeters. Percolation per 24 hours in inches of water. Lower soil. Upper soil. I 2 3 4 0.0338 0.0414 0.0405 0.0526 0.2844 o. 2844 o. 2844 o. 2844 Average. . . 6. 7 10. 104 12.151 12.678 10.408 In field operations only a fraction of the rainfall is absorbed by the underflow even in porous soils, the balance disappearing as surface run-off or evaporation and absorption by plant life. In irrigated sections in Colorado, Professor L. G. Carpenter's measurements show a return to the rivers of 30 per cent or more of the water applied for irrigation where the depth of the annual application of water to land aggregates about 30 or more inches; the measurements also indicate a return to the river by under- flow of i cubic foot per second constant flow for each 1000 acres of irrigated land for the Poudre district; for the Upper Platte district i cubic foot for each 430 acres, and in the Lower Platte the same amount of return water for each 250 acres, or corre- sponding amounts expressed in another unit of measure of 414,- 720, 964,480, and 1,658,880 gallons per day per square mile, respectively. The difference, Professor Carpenter states, "is due mostly to the greater distance for the seepage to reach the main stream, and to the times and amount of water applied." It has taken many years for the seepage water from irrigated dis- tricts to fill the underground storage reservoirs and correspond- ingly to raise the water-table sufficiently to produce the above- GROUND-WATER SUPPLY. 45 stated underflow into the rivers, and doubtless an equilibrium is not yet altogether established. In some instances the water- table has been raised forty feet or more. It is impossible to tabulate the underground run-off per unit of area to serve as a guide in estimating ground-water yield except in particular cases and for local guidance only. In some instances where the collecting area is large and flat and the soil is permeable in a rather humid climate, about 30 per cent of a minimum annual rainfall and 50 per cent of the maximum annual rainfall, or about 40 to 45 per cent of the average annual rain- fall, is considered to be a safe basis of estimate. The average rainfall is perhaps a safe basis of estimate where there is exten- sive underground storage for the reason that this storage can be drawn upon for deficiency of yield during the periods of abnor- mally low rainfall. Thus for an average rainfall of 38 inches covering a period of 50 years of record, 40 per cent, or 15 inches, may be considered available underground run-off, amounting to an average daily yield of about 716,000 gallons per day per square mile. In order that this volume of water may pass away freely without water-logging the surface soil, there must be a suffi- cient depth of porous gravel formation beneath to admit of free lateral movement of the water and a free outlet. Thus upon the assumption that the body of moving water must pass through a layer of sand one mile long we find by computation, allowing one-third the volume of sand to be void space, that in order to discharge 716,000 gallons per day the sand layer should be at least 54 feet thick for a velocity through the sand of i foot per day, 27 feet for a velocity of 2 feet, about 18 feet for a velocity of 3 feet, etc., requiring respectively a water-table slope for a No. 50 sand, which is an average water-bearing sand, of 8, 16, and 24 inches, respectively, per 1000 feet. But in a very expan- sive flat valley where there is little opportunity for surface run- off, also where there is only a comparatively thin layer of water-bearing sand, say 18 to 20 feet in depth, the slope of the water-table must necessarily be comparatively light, in fact so light that a water-logged soil would result were the underlying sand no coarser than the No. 50, which has been assumed. The 46 WATER-SUPPLIES. heavier slopes above computed could only obtain in localities where there is corresponding ground-surface slopes, as in the sandy coast territory. These examples serve to illustrate the relation of the vari- ous factors which it is necessary to consider in estimating ground- water yield with a reasonable degree of accuracy. But the matter may be carried a step further, and the relation of these several factors with the length of development required in order to col- lect the ground-water may be shown in the form of a diagram as in Plate V on opposite page. The diagram contains lines of slope for various grades of sand, a line of velocity in terms of the voids in the sand assumed to be practically one-fourth of the volume of sand, and a curve of length of development required to furnish 1,000,000 gallons of water per day for stated rates of yield per lineal foot of devel- opment from a sand stratum 35 feet in depth measured from the water-table downward. The 35 feet of depth of saturated sand is purely an arbitrary depth and is considered simply because it is the actual minimum depth of a saturated gravel in the particular case for which the diagram was originally pre- pared. In the diagram the line of water-supply development is assumed to have a positive feed from both sides, hence the stated rate of yield is double the yield from one side only. The ap- plication of the diagram is readily understood. Having made a boring on the site of a proposed water-supply development and by several analyses determined that the average effective size of the water-bearing sand is No. 40, and by levels of the water surface of various convenient wells in the vicinity, either bored for the purpose or domestic wells in an undisturbed state, having found that the water-table has a slope of i foot in 1000 feet, we start at the i-foot mark on the slope scale of the diagram, move horizontally across the diagram to an intersection with the slope line of a No. 40 sand, then trace vertically the line of intersection with the length of develop- ment curve, then horizontally from that point of intersection to the development scale and read the length there indicated; the same vertical line carried to the velocity line, then to velocity scale, will give the velocity of flow in terms of voids in the sand, Scale of Ground Water Slope in Feet per 1000 Feet. to co Scale of Length of Developm ml in Feet to'Y Scale of Velocity in Feet per Day 4 8 IV A TER-SUPPL1ES. and also if carried to the bottom of the diagram will give the yielding capacity of the sand from two sides per lineal foot of de- velopment for the stated depth of 35 feet. Should the depth of water-bearing sand be either more or less than the assumed 35 feet of depth, the yield of water per lineal foot of development as as- certained from the diagram in the manner above described should be multiplied by the ratio of the actual depth to 35 and the point of the development curve vertically above the corrected yield per lineal foot will then give the desired length of development. In other words, the yielding capacity of the sand is thus approxi- mated, but whether the actual feed is sufficient to support such a yield is a question which must be determined by a survey of the catchment area and examination of the porosity of the sur- face soil. The use of the diagram and other data herein given is designed as a guide to the judgment in estimating the yielding capacity of a territory selected as a suitable site for a ground-water supply. Of course where supply works are already developed and in use for several years the yielding capacity of the sand-bed and its supplying territory is measured by the amount of water actually pumped. There is no adequate substitute for such a positive test, provided the mechanical means of taking the water out of the sand is in nowise throttled, and provided the physical data bearing upon the effect of the pumping upon the ground-water table are collected and carefully studied. In the absence of such infor- mation there is no way of testing the full yielding capacity of the supplying territory until the rate of pumping shall have progressively increased up to the breaking-point, or that of absolute refusal of the ground to deliver the water in the vol- ume required by the pumps. This experience often puzzles a water-works management and may lead to a dilemma if tech- nical studies have not been pursued in anticipation of a demand for extensions and improvements. The development of ground-water is accomplished in vari- ous ways, but the simplest way is probably the single open well. Of this method there is little to be said because of its simplicity, except that it is the method often adopted by small towns and occasionally under exceptionally favorable circumstances by GROUND WATER SUPPLY. 49 cities of considerable size. The open well sometimes serves the triple purpose of storage-well, receiving-well for galleries or a gang of tubular wells, as well as for individual water-supply pur- poses. An example of this kind is illustrated in Plate VI, which shows a small open well receiving the siphon pipes from two lines of tubular wells. The development lay at the foot of a hill bordering a piece of swampy ground supplied by springs and was projected with a view of intercepting the underflow feeding the springs referred to. The supply of water afforded by the wells was small, about 100,000 gallons per day, but suffi- cient at the time for the supply of the village for which it was developed. Wells of this kind, when penetrating deeply a heavy and exten- sive bed of water-bearing gravel, supply water in large quanti- ties, but may become rather expensive disappointments when they simply uncover a thin layer of sand or penetrate what may be termed a pocket of gravel. In the one instance the depth of supplying sand is too small to admit of either a suffi- cient storage or a flow of water; in the other instance the pocket of gravel yields water bountifully at first, but finally fails as the stored rainfall representing perhaps years of accumulation becomes depleted. A case to the point is an open well 30 feet in diam- eter and 40 feet deep which uncovered a thin layer of sand about 3 feet deep under a deep heavy soil. The capacity of the well was but 126,000 gallons per day even when reinforced by two 6-inch holes drilled into sand rock underlying the bed of sand. In several other instances wells 30 to 50 feet in diameter com- pletely failed within a year because of either an insufficient sup- plying area or an exhaustion of a sand-pocket, notwithstanding the fact that a short-time pumping test developed the presence of considerable water. Failures of this kind are frequent with small water-works, but with some degree of justification when insufficient funds do not admit of seeking and developing a more distant but more permanent source of water-supply. Similar in character and almost as simple as the open well is the filter-gallery which parallels a stream for the purpose of intercepting and collecting the underflow through a body of gravel. Like the open well the exposed gravel bottom of the GROUND-WATER SUPPLY. 51 gallery furnishes the supply of water which is delivered into a receiving- well within convenient reach of pumps or into a gravity pipe connecting with some distant reservoir. Galleries of the latter kind connected with a reservoir of large capacity may run continuously, but should the rate of discharge exceed the rate of underflow replenishment a gradual depletion of ground storage must ensue and eventually a gradual reduction of yield must follow. The reason of this is plain when it is considered that the maximum head or pressure of water actuating the delivery into the gallery depends upon the depth of the gallery below the water-table and the delivery depends upon the porosity of the gravel. Whenever a continuous discharge from the gallery causes the water-table to fall progressively, replenishment is evidently exceeded, the actuating pressure falls and propor- tionately the rate of yield of the gallery decreases until an equi- librium between replenishment and yield is established. A comparatively thin bed of coarse sand and gravel not far from the surface of the ground is the most favorable condition for gallery development. The gallery should be located as far as practicable below the water-table in order to utilize to the fullest extent the storage which a gravel deposit affords for occasional heavy draft of water. El. 110 xrtSffi River _ 100 NirurITG"rou"nd"wIt~eTLe"v"eT"" 90 Clay Substratum 80 FIG. 2. Fig. 2 illustrates the depth of a deposit of water-bearing gravel which has furnished the water-supply of a large-sized city for over fifteen years. The diagram shows the normal ground-water table to be about 18 to 20 feet above an impervious clay substratum. The water- supply is coUected in a system of galleries aggregating 2340 feet in length leading into a combined water-supply and suction well about 47 feet in diameter containing in the aggregate a gross infiltration area of 12,500 square feet. At the time of which we are speaking, the average daily consumption was nearly 3,000,000 5 2 WA TER-SUP > PLIES. gallons per day and infiltration was at the rate of 240 gallons per square foot of gross area or about 300 gallons per square foot of net area. This rate of infiltration has been increased fully 60 per cent upon occasions requiring heavy fire service. A water-level test with the gallery delivering nearly 3,500,000 gallons of water showed a drop at the gallery of 3^ feet below normal water-table level and an actuating slope of the ground- water of about 7 feet per 1000 feet, corresponding to a lateral veloc- ity of approach of about 6 feet of solid water per day through the i6J feet of saturated gravel near the gallery, assuming water to be supplied equally from both sides of the gallery. The average coefficient of porosity is estimated at 1000 and the effective grade of the sand a No. 36. We regret to have no mechanical analysis of the sand, but if the curve of the water-table under draft be com- pared with the Muscatine curve as shown by Fig. 3, the higher resistance of the sand referred to becomes apparent. Heavy draught i sand E 1G I 15 E 14 = 18 E 12 = 11 Ligh raught in sand and Gravel -10 pt. 25 pt._26 = 8- = 7 11109S7G543210 FIG. 3. Diagram of Ground-water Curves. The level of the bottom of the galleries ranges from 8 to 9 feet below the normal water-table, leaving several feet of ground storage between the gallery and the clay substratum which cannot be drawn upon in emergencies. The importance of making this deeper storage available justifies the construction of a gallery somewhat deeper than the original galleries whenever the demand GROUND-WATER SUPPLY. 53 for water-supply extension arises. The expense entailed in carry- ing out this work may be comparatively heavy, but nevertheless not so great as that of providing equivalent emergency surface storage, which would preserve unimpaired the quality of the ground-water. Possibly the local conditions warrant this form of water-supply development above others; at any rate the success of the original galleries in supplying so large a volume of water as 1,000,000,000 gallons or more annually must certainly inspire sufficient local confidence in the form of construction as to justify the preference. It will be noted in the preceding illustration that we have made an estimate simply of the lateral velocity of the flow of water through the sand as it approaches the gallery to supply the draft of water therefrom, and not of the vertical velocity of infiltration through the gravel at the bottom of the gallery, for the reason that it is the permissible velocity of approach to the gallery that governs the rate of infiltration. In turn the velocity of approach is con- trolled by the grade or porosity of the sand through which the water must flow in approaching the gallery. So far as we know there is no record of measurements taken to ascertain the influence of the river adjoining the gallery upon the yield of ground-water, nor yet of any examination or survey of the extent and general physical characteristics of the water-bearing gravel underlying the river valley. Thus far the large amount of water which has been drawn from this gravel-bed does not appear to have affected the general characteristics of the water- table, which fluctuates with the rise and fall of the adjoining stream. It is a case where no interest dependent upon the source of water- supply seems to have suffered thus far from a neglect of making a thorough examination of the water-supplying capabilities of this particular locality. However, the importance of the city and the magnitude of the investment now at stake in this case, as well as in any other similar case, should suggest to a prudent water- works management the desirability at least of making such ax- aminations as admit of approximating the yielding capacity of the existing source of water-supply and thereby become informed of the probable limitation to be placed upon future development work. Theoretically the limitation of filtering-gallery extension is 54 WATER-SUPPLIES. indefinite so long as due regard can be given to the hydraulic con- ditions which are necessary to produce the required flow of water within the gallery and to structural requirements. The rate of infiltration should not be so great as to disturb seriously the sand underlying the usual ground floor of the gallery. The depth of gallery construction below the normal water-table possesses a very decided limitation from the standpoint of cost ; in fact such construction is confined in this particular direction within such narrow limits that it is seldom considered a feasible method of water development in localities where deep water-bearing strata prevail, particularly when the coarse and more desirable stratum is near the bottom and much below the water-table. Even where the gravel-bed is shallow, as in the preceding illustration, the supe- riority of a gallery over other forms of development is often ques- tionable. Upon this debatable point it is thought that much de- pends upon the mechanical make-up of the water-bearing material and upon the cost of maintenance of gallery construction com- pared with other forms of construction. For example consider what other form of water-supply develop- ment can be substituted for an infiltration gallery, in the deposit of water-bearing material of which Fig. 2, on page 51, is a sketch. Several large open wells connected in series by a gravity-flow pipe and finally with a pump-suction well could scarcely prove an ade- quate substitute because the expense of constructing the wells and the connecting gravity pipe lines would fully equal the cost of a gallery of equal yielding capacity. This fact seems clear upon the face for the reason that all the conditions affecting the yield and the cost of construction and maintenance are identical in the two cases. But were the series of wells connected by a series of siphons of gradually increasing capacity as the suction well is approached some saving in the investment would result, although the cost of operation and maintenance of the water-supply works would be somewhat increased because of the necessity of having to provide and maintain a means of removing air from the series of siphons. The uncertainty of a prompt response of a series of siphons to the fluctuating requirements of consumption and the inaccessibility of the several siphons would militate against this method of development even at a reduced cost of construction. GROUND-WATER SUPPLY. 55 A more unique form of construction, shown by Fig. 4, would be to construct a main siphon pipe parallel with but to one side of the series of open wells and on a continuous rising grade to the suction well where it should terminate in a vertical down-take pipe dip- ping several feet below low water in the suction well and capped 5 Branch Pipe J i i i Main Siphon' PLAN OF SERIES OF WATER SUPPLY WELLS > Suction Well ..-To Air Pump ELEVATION FIG. 4. at the top by a large vacuum-chamber from which entrailed air could be exhausted by means of a vacuum-pump. Each open well should then be connected with the large siphon pipe by means of a branch pipe of sufficient capacity to accommodate the yield of the well in the manner shown by Fig. 5. SECTION THROUGH SUPPLY WELL FIG. 5. Supply Well Junction Well FlG. 6. The objections to multiple siphons in the former arrangement of open wells are altogether overcome by the arrangement just 56 WATER-SUPPLIES. described. There is only one siphon and only one point in this one siphon where there is any possible chance of an air-lock, namely, at the vacuum-chamber on or near the down-take inlet to the suction well, and then only through neglect of the attendant at the pumping-station. The vacuum in the siphon pipe can always be maintained and the water-supply works can always be in shape to respond to any demand of consumption up to the supplying capacity of the wells. The only chance for a break is through the exhaustion of the supply of water in any one well to the extent of exposing the mouth of the branch supply pipe to the siphon, but this danger of a break of the vacuum may be avoided by a small suction well sunk inside the supply well to some depth below the limit of suction as indicated by Fig. 6. This form of construction usually requires less investment in water-supply works than does an infiltration gallery. The water- supply wells may be sunk with proper appliances by dredging the material from the inside as the curb descends through its own or a superimposed weight, thereby permitting all construction work to be accomplished above the ground-water table with but little if any pumping for construction purposes, which is the chief source Of expense in the construction of an infiltration gallery. The cost of operating and maintaining the well system of sup- ply should be no greater than that of the gallery system of supply. Besides a series of wells can be more readily sunk to a depth which will make available practically all of the permanent storage in the water-bearing material, as would be the case in the illus- tration referred to were the shoe of each of the supply wells to penetrate the water-bearing material to a level 4 or 5 feet above the clay substratum. The general arrangement would perhaps appear more balanced were the supply wells distributed on either side of the siphon pipe, even though in the matter of yield there might be no material difference, the wells being naturally distributed in a direction normal to the slope of the natural ground-water table. Consideration of the matter of an economical substitute for an infiltration gallery may be carried a step farther by attempting to find a satisfactory substitute for the large open well. This step naturally leads to a consideration of a series of small tubular GROUND-WATER SUPPLY. 57 wells ranged along either side of the large siphon pipe which has just been described. These small wells may be either open or closed, driven or bored, according to present practice. Imagine two rows of small wells, one on either side of the siphon pipe above described and close enough together to absorb the entire flow of water that the water-bearing material is capable of passing at the maximum permissible slope. For the purpose of ascertaining what the slope should be to produce a maximum discharge, or, in other words, for the purpose of defining the limit to which the water- table should be depressed near such a system of wells as has been described in order to produce a maximum velocity of approach through the sand and accordingly a maximum discharge, refer- ence is made to Fig. 7 and the following solution. FIG. 7. Let v = velocity of approach of the ground- water =fo'; h-x i =the slope of ground-water = y ; h =the depth from the natural water-table to substratum; x = " " " draft /=the distance from wells to the point where the draft water-table meets the natural water-table; a =area of saturated section at or near the wells =x times unity for a unit length of section; <2 = the discharge for 24 hours =av\ hence Q=av =aki =xki for unit length of section. 58 WATER-SUPPLIES. h-X Substitute in value for Q the value of i= -, k then Q=jx(h-x). Now the condition which makes the factor x( h x) a maximum is the condition which gives a maximum value for Q and accordingly a maximum velocity of approach through the sand. It is found that the value of x which makes this factor a maximum is \h. Hence, by substitution, k Ik Q = -(h %h)%h =-r jh 2 in cubic feet per day. In order to reduce to a discharge in gallons per 24 hours, con- sidering the water to approach equally from both sides of a system of wells, multiply the above equation by 2 and 7.5, making 0-3.757**. Reference has been made to an illustration, Fig. 2, where h =20 feet and k = 1000, and where the observed value of / was about 500 feet; hence for that case 3.75X1000X20X20 Q = - =3000 gallons per day. That is to say this computed rate of discharge is the maximum dis- charging capacity of the stated grade of sand under stated con- ditions of slope and depth of water-bearing material independent of any question of rainfall or river support, and is representative of the conditions which make the best use of the available ground storage for emergency draft. It is evident that a gallery which is sufficiently low in the ground to depress the natural water-table over it one-half the depth of the water-bearing stratum receives the maximum rate of infiltration. But when a system of wells is substituted for a gallery, the direct current of approach must break up into a GROUHD-WA7ER SUPPLY. 59 series of converging currents of rapidly increasing velocity as each well of the series is approached. The larger the number of the wells in a given distance the less becomes the several indi- vidual areas of converging flow, until finally with the small wells practically in contact the gallery conditions become duplicated in effect. When the wells are a considerable distance apart, as they usually are, the quantity of water entering the strainer of any individual well must equal the quantity which approaches it by direct flow and feeds the zone of the converging current which feeds the well, consequently the quantity of water flowing in a prism of a length equal to the distance between the wells and a depth equal to one-half the normally saturated area divided by the exterior area of the strainer gives the velocity of flow from the sand in contact with the strainer subject to such cor- rection as the relatively small area of the strainer openings and well interference may require. Strainers. The ordinary well-strainer possesses but about 13 to 15 per cent of the entire metal surface as openings, and not more than one-third of this per cent is available for use, con- sequently the velocity of flow through the openings must be very much more than the velocity of flow through the sand at the surface of contact of the sand with the strainer. There are certainly some well-defined principles upon which the area of the openings in, and the length of, a strainer should be based. Evidently the openings should have a form which offers the least resistance to the flow of water and a size which can absorb the water as fast as it is delivered from the surrounding sand. Of course the geometrical form of opening which offers the least resistance to the flow of water is the circle. But while practical considerations sometimes require a departure from the circular form of opening they do not require a proportionate departure from the effective discharging capacity of that form of opening; for instance, a departure from a circular to a narrow rectangular opening should be accompanied with a compensating increase of area of the slot in proportion to its greater resistance to the flow of water. Usually the head or pressure which actuates the flow of water 60 WATER-SUPPLIES. through the strainer opening into the well is the negative head produced by pumping. Whenever water does not enter the well fast enough through strainer openings of insufficient area the pump gradually increases the vacuum in the well, within prac- tical limits of course, in an effort to secure a feed of water. The resulting but gradually increasing pressure outside the strainer eventually packs the sand about the strainer to the extent of throttling the already deficient area of openings and proportionately the feeding capacity of the strainer. A system of wells thus throttled will usually be found to yield a gradually decreasing volume of water and finally to decrease the feed to the pumps to such an extent as to render the method of water- supply development more or less of a failure. This throttled condition of strainer is often the direct result of the use of a strainer with openings so small that the fine sand cannot enter the well. The theory forming the basis of this practice may be correct when the sand in which the strainer is embedded is generally fine and of uniform texture, but it can- not hold good where the layer of sand is an assorted mixture in which fine sand is a comparatively small percentage of the bulk, for in that case the strainer should be coarse enough to allow the finer sand to pass through the openings into the well and to be removed mechanically. In fact it is often a most excellent practice to give each well a preliminary washing by means of a directly attached pump operated at a rate of pumping some- what in excess of that which would prevail in general service. Any portion of the sand thus drawn through the openings of the strainer and not ejected' from the pump with the water can readily be withdrawn with a sand-bucket. The remnant of coarse sand about the strainer prevents the subsequent ad- vance of fine sand in the same manner that the graduated gravel layer of a sand-filter prevents sand entering the underdrain. The danger of further movement of fine sand after such a washing is very remote because of the rapidly decreasing velocity of flow through the sand as the distance from the center of the well increases. In order to determine what this velocity may be and the law by which it increases as the well is approached it is necessary to devise a mathematical expression embracing; GROUND-WATER SUPPLY. 61 the law or principle of radial flow. Assume that the water flows in a radial direction towards the well through a series of con- centric cylinders C, Ci, C 2 . . . W (Fig. 8) of a depth x, X i, x 2 . . . #,, measured from the impervious stratum YY to the water-table assumed by the approaching water. Throughout each concen- tric cylinder the velocity and velocity head are constant and are inversely proportional to the distance from the center of the well. Moreover, the velocity through any cylinder C multiplied FIG. 8. by its distance from the center of the well is equal to the velocity of flow through any other section C multiplied by its distance from the center. Hence by representing the law of variation of velocity by the general formula p'dv=v'dp=vp= constant (c), where p equals any distance from the center, the following gen- eral formula may be written: c v=. P (i) 6 2 W A TER-SUPPLIES . It is also known that the quantity of water which flows through any cylinder C must also flow through any other cylinder Ci, 2- In the general expression for velocity v =ki, where k =the factor of resistance and i is the slope which for any in- finitely small arc of the curved water-table of radial flow may be expressed by - Hence By substituting the value of v of equation (i) in equation (2) there follows: c ,dx dp _= or c=kdx y p dp p or (3) Now if the distance from the well to the boundary where the water-table of approach to the well meets or becomes the natural water-table be represented by R with its corresponding value of x=h, the natural depth of the water-bearing material, and the distance from the center to the exterior of the well by r, where the value of x =x, we may substitute these values in equa- tion (3) and solve for C. Hence c\og e r kx =C. Now placing the values of C equal to each other there follows: cpog, (R+r) -log, r] =k(h-x). k(h-x) i ( R+r \ log, ( ) (4) * The theoretical portion of this demonstration is suggested by Prof. Slichter's analysis of radial flow in Nineteenth Annual Report of U- S. Geological Survey. GROUND -WATER SUPPLY. 63 Substituting the value of c of equation (4) in equation (i) an expression for velocity is found: For the particular case of velocity or discharge at the cir- cumference of the well let p=r and Q=av=2nrxv, and by sub- stitution in equation (5) an expression for discharge follows: -x) log, Since the expression for Q is in terms of the variable x in the term x(h-x), there is some value of x which makes this term and consequently Q a maximum. Let u=x(h x), then du = hdx 2xdx. du j=h-2x=o or x=h. ax d 2 u Hence the above term and consequently equation (6) become h a maximum when =x . 2 Now by making this substitution in equation (6) and reducing, there results . Vmax. = A similar substitution of x=%h and p=r in equation (5) gives a value of velocity corresponding to a maximum rate of discharge at the well circumference as follows, wherein d= diam- eter of well: kh 64 WATER-SUPPLIES. In formulae (4) to (8), inclusive, the natural logarithm (\og e ) is used and may be found by multiplying the common logarithm by 2.3. The reduction is made in the formulae which follow and the logarithm indicated by c.l. Formulae (5) to (8), inclusive, should be multiplied by a factor of resistance of flow from the sand through the strainer, and so far as investigations have gone they point to a range of values of 0.17 to 0.25. Accordingly the reduced formulae become kh 2 Center Line of Filter and Drain FT i ^ Reservoir ^> ,* Manhole . o i- "- 1 i n>i r \z \ Htili iiU ^i ' 1 Filter > oi^rainjr S l 08 "" 1 ^ lo'i 3 Center Line of Filter and Drain i Re^rvoir'o l* IS ,,l* L * lo:<) ^* 10*1 ^ ] *2 ' ^ *-^f e r- 2 -- 1 Plan of Purification Works at Liberty, Mo. Richmond works for the reason that it was built at the same time as the water-supply and pumping station. It is rectangular in form and constructed of 1-3-5 lola-Portland cement concrete reinforced with the Johnson corrugated steel rods. Plate XIII shows the plan and the elevation of the purifica- tion works. Plate XIV is a view looking down upon the roof of the filters and enclosing parapet walls within which dirty filter sand is washed and then stored. The tower enclosing the aerator is i o 6 WA TER-SUPPLIES shown immediately behind the men sitting on the parapet walls and back of the tower walls is the wall of the pump-room, rest- ing upon the reinfofced-concrete walls enclosing the clear- water basin. Plate XV shows the high-pressure pumping-engine installation. The engine sets upon the roof of the clear-water basin, which is also the floor of the engine-room. Through the open doorway in the partition wall the fronts of the boilers may be seen. The bottom is a continuous slab of concrete for both the clear-water basins and the filters, but independent of each other. The side walls and roofs are monolithic, but so formed that the concrete box composing the filters is entirely independent of that composing the clear-water basin. The several partition walls in the clear-water basin are so formed as to make two regulating wells, a pump-pit for the well pump, and two compartments for the storage of filtered water. A concrete roof covers the portion where water is stored and forms the floor of the engine-room, a stairway leads down into the pump -pit, manholes are placed over each division of the clear-water basin, and wooden covers protect the regulating wells. The side walls of the clear- water basin are the foundation walls of the engine-room part of the pumping-station. The high-pressure pump sets upon steel eye- beams molded into and made a part of the roof of the clear- water basin. The foundation walls of the boiler-house and boilers rest upon natural earth and are not monolithic with the clear-water basin. The filters are divided by a longitudinal wall through the center, forming two equal compartments. A concrete roof covers both filters with the exception of about 5 feet at the end of the filters next to the building. A parapet wall 3 feet high extends entirely around the covered portion of the filters and around the opening in the roof. A brick tower about 5 feet high stands upon the parapet wall surrounding the large openings into the filters. This tower encloses two sets of aerator trays, one set of four for each filter. These trays differ from those of the Rich- mond works only in lineal dimensions, being 3 by 4 feet. The water in showering through the trays drops about 10 feet. GROUND-WATER SUPPLY. in The covered portion of the filter-roof enclosed by the para- pet walls is for the storage and washing of the dirty sand removed from the filters. The dirty sand is skimmed from the filter by hand, but elevated onto the roof by means of a hydraulic ejector The underdrain of the niters is composed of three parallel lines of 4-inch vitrified tile with open joints and 12 inches of graduated road metal of practically the same assorted sizes as those of the Richmond works. The mechanical analysis of the sand, which is 4 feet deep, is as follows: Rejected by No. 6 sieve, 1.25 per cent. Passed " " 6 " 98.75 " " <{ " 10 " 95.42 " " " " 14 " 88.96 " " " " " 18 " 84.90 " " " " " 20 ll 60.00 " " " " 40 " 40.54 " " cc cc cc cc The effective size is No. 59. Uniformity coefficient is 2.95. All the valves for the operation of the purification works as well as of the pumping machinery, of which there are 15, are within easy reach of the engineer from the engine-room floor; the only outside valves are the two ejector valves beneath the roof of the filters. The boilers face the engine-room and can be continuously under the eye of the engineer. Both the Richmond and the Liberty water-supply works are operated by one attendant except at the time of scraping the filters, when the attendant of the Richmond works requires a helper because the lack of facilities for mechanically removing the sand and for storing it on the roof of the filters. These have been supplied in the Liberty works. The subsiding basin of the Richmond works admits of water softening. The entire process by which the water of both works is puri- fied is entirely a natural process and is so simple that the ordinary water-works attendant has no difficulty in conducting all the H2 WA TER-SUP PLIES. operations successfully without the aid of skilled assistance except for a few days when the purification works are first started, and then only to teach the attendant the principles and the few mechanical restrictions under which the purification works should be operated. The hygienic quality of the water which is the product of such purification works as the two just described is of the highest rank. The aeration which the ground-water receives not only oxidizes the iron but also substitutes air for the gases so often present in an iron water. Filtration imparts to it a clearness which is always delightful in a drinking-water and a perfect free- dom from the inky taste of the fresh well-water. In fact there is so complete a transformation of the hygienic qualities of the water in passing from the well through the aerator and filter to the clear-water basin that, so far as one may base a judgment upon taste and appearance, they are waters of totally different characteristics, and the same statement may be made of the water with regard to many domestic uses. The method of purifying the water leaves no room for the suspicion of the presence of unpleas- ant or undesirable by-products of chemical treatment which so often attaches to the water from filters or settling-basins which perforce must use a coagulant to remove the sediment from surface-water. In the one instance the chemical action result- ing in the oxidation of the iron is altogether natural and diminishes the amount of both mineral and organic matter present in the fresh well-water, while in the other instance the use of the coagu- lant adds to the dissolved mineral of the raw water and also some- times leaves suspended in a clarified river-water a portion of the coagulant in a hydrated form. No possible exception can be taken to the bacterial purity of filtered iron water, for could any suspicion whatever attach to the well-water naturally filtered, the suspicion is entirely elimi- nated by the second process of filtration in covered filters and the subsequent storage of the doubly filtered water in a covered storage basin. No artificially filtered surface-water can surpass the doubly filtered well-water in hygienic or bacterial purity. Moreover, the filtered iron water approaches more nearly the popular conception of a desirable drinking-water than any puri- GROUND-WATER SUPPLY. 113 fied surface-water can approach such a quality, and therefore, in small towns particularly, is the more readily accepted as a substitute for the neighborhood spring, the private well, or even the cistern, while in large towns its advent as a hygienic water would be hailed with an expression of the most genuine approval and indorsement from every side. With large towns the only questions to be considered in connection with the development and purification of a ground- water impregnated with iron are the ones of quantity and adaptability to mechanical uses. The quantity is unquestionably large in such valleys as those of the Missouri, Mississippi, Platte, and Kansas Rivers, where there is unquestionably river reinforcement to the rainfall feed of the underlying gravel-beds. But even though sufficient water may not be obtained for a full supply of water of a large city which must otherwise depend upon purified river-water for its supply, a partial supply of iron water aerated and then mixed with that portion of the supply derived from the river will through the coagulating property of the iron aid in the removal of sediments as has been pointed out in the paragraph Natural Coagulation of the chapter entitled River-water Supply. Sometimes the mixture of different waters supplies food for the natural micro- scopic life contained therein, and accordingly aquatic life may de- velop luxuriantly and upon dying, after the consumption of the food-supply, give to the waters an offensive odor and taste. This trouble need not be feared when the mixed waters are stored in the small storage basins of purification works, for there is not sufficient time for its development. Ground- water is evidently more desirable hygienically than impure surface-water which requires clarification and purification, whether it is usable directly as removed from the ground or re- quires previous treatment to remove objectionable minerals; besides when ground-water must be treated, the works and plant required for this treatment are always more condensed, less expensive, and require less skilled supervision in operation than the purifica- tion works needed for the purification of muddy and impure surface-water. It frequently pays a city to go a long distance to secure that sort of water-supply rather than to install purifi- cation works to cleanse a nearer but impure surface-water. The H4 WATER-SUPPLIES. natural facilities in this direction are not confined to the require- ments of small cities and towns, but by proper forms of develop- ment they may be made available for cities of considerable size. It will certainly pay any city to make thorough investigation of the availability of ground-water in its vicinity before grappling with the highly expensive problem of surface-water purification, for expensive construction and maintenance must precede success- ful and satisfactory operation of purification works. A zeal to stimulate the growth of high ideals as to what constitutes a standard of hygienic purity and to give struc- tural expression to these high ideals should not lead one to such extreme lengths as to claim for the purification works which depend upon ceaseless vigil for efficiency of action the loftiest structural expression of such ideals, but rather influence one to accept such works as desirable and necessary only in the absence of means and facilities of obtaining structural expression in a simpler, more direct, and less expensive form, wherein skilled surveillance is reduced to a minimum because of the fact that the source from which the water-supply is derived is either unpolluted or so surrounded by natural safeguards as to render artificial pollution a remote probability or even a bare possi- bility. All energetic efforts towards progress tend to develop a few extremists either in fact because of their extremely optimistic or visionary views, or so called because their energy and fore- sight keep them well in advance of the general procession. A switch to by-roads from the general direction of progress, reac- tion, retrograde movement, a return to the old but newly paved and better-lighted route, a renewed advance are the accompani- ments of general progress in technical as well as in other every- day pursuits. Thus upon the opportunities of a community to learn of and appreciate progress, upon its means as well as upon its needs, depends very much the perfection of water-supply development in individual cases. Often simple though fairly effective methods of water-supply may lead to a quicker and better appreciation of high ideals of hygienic purity than more complex methods which require the exercise of special skill in the attainment of good results. Accordingly clear and wholesome natural water GROUND-WATER SUPPLY. H5 either at or below the surface of the ground is of first considera- tion, ground-water treated when necessary to improve its quality for general use is of the second rank, and artificially purified surface-water should be acceptable in the absence of facilities for obtaining either of the former grades of water-supply econ- omically or in sufficient quantity. CHAPTER II. RIVER-WATER SUPPLY. RIVERS usually constitute a frequent and unfailing source of water-supply and are probably more in demand for this pur- pose in the central and southern portions than in any other sec- tions of the country. But it is seldom that the river-water can be used without some sort of purification. Purification works add much to the expense of the construction, maintenance, and operation of a system of water- works, and when successfully operated demand no small amount of attention from the manage- ment and attendants. In the East, sewage and manufacturing wastes constitute the chief source of river pollution, while in the Middle West, where these sources of pollution are relatively less, there is an exceedingly large amount of sediment carried in suspension by nearly all rivers and streams which needs to be removed. Problems of water purification, while having the same object in view in all sections of the country, receive solu- tion in a manner differing very much in the mechanical details of the purification works. For instance, the filter is usually considered the essential requirement for removing sewage pollu- tion, and the settling-basin or a combination of the settling- basin and filter for clarifying muddy water. In order to present the practical side of the several methods of water purification, it is necessary to pursue the description considerably in detail, particularly that portion of the descrip- tion relating to the preliminary treatment of river-water in preparing it for filtration. Clarification alone is necessary when a naturally muddy water can be made wholesome by removing the sediment which it contains. This is frequently accomplished by the use of the 116 RIVER- WATER SUPPLY. II; settling-basin. But when the purity of the water aside from the sediment which it may contain is in question, the water must be subjected to some additional treatment before it can be considered wholesome. The additional treatment usually consists of sand nitration or the use of a germicide either to remove the bacteria infesting the water or to kill them outright by the toxic effect of some applied chemical. The essential ob- ject to be accomplished in either case is the removal of objection- able bacteria that may have entered the source of water-supply with any sewage discharging into the source from which the supply is taken. There is no sharp dividing line between the process of simple clarification and that of bacterial purification of a water, par- ticularly when the natural water contains much finely divided clay in suspension; for then the process which is necessary to secure a complete clarification artificially will often relieve the water of bacterial life to such a degree as to render it safe and wholesome. In showing the difference between a process of simple clarification and one of purification as now practiced, it is necessary to follow out the present methods of treating muddy water somewhat systematically and in detail. Settling-basins. The settling-basin as a factor in water clarification has received its most extensive development in cities along the Missouri and Mississippi Rivers. Here the com- mon practice for years has been to depend upon sedimentation for clarification. Accordingly the basin is usually divided into at least four divisions, each division having a capacity for water of about one day's consumption. Two distinct methods of operating the basin are followed: one is termed the fill-and- draw method, the other the continuous-flow method, the water- supply being abstracted after subsidence from each of the four divisions in the former method and continuously from a single division in the latter method. The fill-and-draw method embraces a period of uninter- rupted rest of the water in one division of the basin while the day's supply is being abstracted from another division, while a third division is being filled, and while a fourth division is being cleaned. A serious and practically insurmountable diffi- Il8 WATER-SUPPLIES. culty in this method of operation is the one of drawing upon the division containing the subsided water for any large per- centage of the contained water without disturbing and drawing into the effluent pipe a considerable portion of the intensely muddy lower water which has grown dense with deposits from above. The sediment descends very slowly through the lower water before final repose in a compact form at the bottom of the basin, and when in this semi-fluid state it is very unstable and naturally mingles with the less turbid water from above as it eddies into the effluent pipe. Even a more serious objec- tion to the fill-and-draw plan of operation is the one that a river-water does not respond equally on each and every day to the process of natural sedimentation, as the amount and character of the sediment in river-water varies or as the tem- perature changes. Within a single day the water in a settling- basin operated on this plan may change from one slightly turbid to one decidedly muddy and opaque. Moreover, a coagulant when needed must be introduced into the raw water as taken from the river by the pumps, and when so introduced much of it is absorbed or subsides with the heavy sediment, leaving the fine sediment practically unaffected by the process of coagu- lation except when the coagulant is used in excess. The objec- tions mentioned are so serious that the settling-basins orig- inally constructed to operate on the fill-and-draw plan are grad- ually being remodeled to operate on the continuous- flow plan. The continuous- flow method of sedimentation provides for the passage of the water from one division of the basin to another successively, the muddy water being introduced into the first division of the series and the clarified water being stored and abstracted from the last division of the series. Progressive sedi- mentation takes place during the interval of transit from division to division. The simplest method of communication with the series of divisions of the settling-basin is by long depressions or weirs in the division walls, together with suitable by-pass pipes or conduits to facilitate the emptying and cleaning of any one of the divisions without disturbing the operation of the other divi- sions of the series. RWER-IVA7ER SUPPLY. 119 The water upon entering a division of the basin near the bot- tom displaces an equal amount of clearer water at the surface which passes to the succeeding division over a weir in a division wall. The weir method of communication between the basin divisions insures a transfer of the clearest water, which is always near the surface, and the least interference with the process of sedimentation. This may properly be termed the displacement principle of the continuous-flow method. The weirs may or may not be constructed the entire length of a division wall of a basin, the object sought being to convey Drain Gutter inlet Well FIG. 15. Settling-basin with Baffles. the water from one division of the basin to another in a thin sheet that serves to skim, as it were, the surface-water. The coldest winter weather does not cause any interference of ice at any weir, as the water emerges from under the ice on one side of the division wall, flows over the wall at a temperature slightly above freezing, and disappears beneath the ice on the oppo- site side of the wall. A method employed to avoid a tendency to surface currents as the water passes from the weir is to suspend vertically a cur- tain of planks about two inches from the weir. The curtain deflects the water downward to any desired depth. A modification of the displacement principle of continuous- flow is to be found in the use of a settling-basin supplied with baffle-walls instead of division walls. These baffle-walls guide the water by a circuitous route through a single compartment 120 WATER-SUPPLIES. basin upon the theory that the flow, although continuous, is at so low a velocity that sedimentation is progressive during the forward progress of the water. An illustration of this principle is shown [TfpElev. Concrete Surface 9S..5 I Basin 2 \ 1 1 j Ij Bedded in Concrete \^ FIG. 16. Plan of Settling-basin. on Fig. 15, a sedimentation basin designed for Fort Smith, Ar- kansas, in 1896 by the author. The water enters one end of the basin, swings around the several baffle-walls, which are built to the same elevation as the top of the basin enclosing walls, and discharges into a receiving-well at the opposite end of the RIVER- WA7ER SUPPLY. 121 basin in a thin sheet over the well-rim. Although this struc- ture has never been built, it serves to demonstrate the principle upon which baffles are supposed to work in horizontal flow. A modification of this principle can readily be made to produce a flow in a vertical plane. Settling-basins having but one or two divisions are some- la'Inrtuent Pipe from Low Pressure Pump H'Suction to High .Pressure Pump FIG. 17. Plan of a One-division Settling-basin. times operated on the displacement method, as shown by Figs. 16, 17, and 18. Fig. 1 6 shows a water-purification works consisting of a two-compartment subsiding-basin and a mechanical filter-plant. The raw river- water enters division i, displacing an equal volume of water which passes into division 2 over a weir, swings through division 2, and finally passes over the arch wall in the corner of division 2 into the effluent well, whence it passes to the mechanical 122 WATER-SUPPLIES. filters. During the process of cleaning either one of the two divisions of the basin the other division can be operated singly in connection with the effluent well. A three-division basin (not constructed) operated on the displacement plan is shown in Fig. 19. The principle of opera- tion of this basin is similar to that of the two-division basin just described, except for such modification of operation as is em- braced in a three-division layout. Other designs of settling-basins are to be seen on succeeding figures which accompany descriptions on other pages of this chapter. RIVER-WATER SUPPLY. 123 Natural Subsidence. -When a muddy water is delivered into a settling-basin operated either by the fill-and-draw method or by that of continuous-flow, sediment naturally settles to the bottom and the water becomes clarified to a degree. This 30 * Pipe from Reservoir to Pump Well % ^=-=-w--.=r=-..".: - - ; == ^:- - v=--=s=rg/ method of clarification is termed natural or plain sedimentation to distinguish it from the method of sedimentation with the aid of a coagulant. The degree of clarification which can be attained by natural sedimentation depends upon the character of the sediment in the raw water and to a degree upon the viscosity of the water itself. A sediment composed almost wholly of sand descends 124 WATER-SUPPLIES. rapidly and a fair degree of clarification may be reached by natu- ral sedimentation. A raw water of this class is characteristic of the Missouri River during the late summer and the fall months, when the sediment carried in suspension is largely sand with a small percentage of clay. When a considerable amount of clay is carried in the water, there is always a portion of it which is so finely divided and so light that it resists natural subsidence for a long period, even for a longer period than admits of satisfactory clarification in a settling-basin containing four to six times the daily consumption of water. This is the condition of the Missouri River water in the spring of the year and of almost any other detrital rivers of the middle West during either all or a portion of each year, depending upon the character of the soil in the territory drained. Robert Spurr Weston, resident expert of the Sewerage and Water Board of New Orleans, Louisiana, gives 265 parts per million of suspended matter remaining in the Mississippi River at that city after seventy-two hours' natural subsidence. In the Cincinnati experiments conducted by George W. Fuller for the purification of the Ohio River water, Mr. Fuller tabu- lates results of natural subsidence as follows: TABLE I. SUSPENDED MATTER IN OHIO RIVER. (In parts per million.) Range. Original. After 7 2 hours of plain subsidence. Percentage removed. I to 50 ... ^8 I 2 68 51 to 100 7 3 I 74. IOltO25O 166 48 7 I 251 to 500 33O Q? 72 501 to 1000 665 184 72 1000 and over 12 ^ C 222 82 In some observations of sedimentation of Missouri River water the results are as shown by Table II. The observations in this table were made of water passing through the settling-basin of the Kansas City, Missouri, water- works, illustrated by Fig. 20. Observations after a longer period of natural sedimentation could not be recorded, as the water received a coagulant solution immediately after twenty-four-hours ' natural RIVER-WATER SUPPLY. sedimentation. There were occasions, however, before a sys- tematic method of coagulation was introduced when the water was completely opaque and must have contained several hun- dred parts per million of sediment after fully four days' expo- sure to natural subsidence. TABLE II. (In parts per million.) Date. Suspended matter. River-water. Suspended matter in River-water after about 24 hours' natural subsidence. Suspended matter removed bv natural subsidence. Per Cent. January 18, 1900 20 650 80 100 87 7 80.6 24 26 March 10 12 14 490 2315 2520 2OOO I I 60 140 50 325 470 295 714 90-3 93-5 87.1 76.5 74-6 Average.. 2O2 82.7 At St. Louis, where plain or natural sedimentation has been practiced for a number of years, the results are expressed in the following table. TABLE III. Period. Average sedi- ment in raw water, parts per million. Average period of subsidence. Hours. Sediment in subsided water, in parts per million. Per cent of sediment mo\ed. Bissell's Point, 1885-86 1186 24. I O4. OI Bissell's Point, 1887-88 1186 34* 3O< JA Chain of rocks, 19001 1152 60 I6 5 86 In the experiments at Louisville with the Ohio River water the average of five experiments was: Parts per million. Suspended matter 469 Sediment in subsided water, 24 hours' settlement 277 ' " 48 " " 155 126 WATER-SUPPLIES. The per cent of sediment removed is about 41 per cent for twenty-four hours' and 67 per cent for forty-eight hours' natural sedimentation. The remnant of the sediment still suspended in the water- after natural sedimentation is probably of the same general character in each instance referred to, as the average amount of this remnant does not vary much in any of the river-waters named. A greater variation may be found by comparing the results of natural sedimentation of the several river- waters at seasons of the year when turbidity is most persistent. Sedimentation is slower in the spring of the year when the RIVER-WATER SUPPLY. 127 water is chilled because of v the greater viscosity of the water at this season of the year. There is no practical way of remedy- ing this difficulty. It is evident from what precedes that natural sedimentation is not an effective means of thoroughly clarifying muddy river, water, although it is a very effective method of removing the heavy sediment which is simply held in suspension by the com- plex motion of a flowing river. The remnant of sediment in a naturally subsided water may amount to as much as i cubic yard for each 1,000,000 gallons of water or even more. The result of natural sedimentation for clarifying a public water-supply taken from a detrital river has been found efficient in no city which has thus far tried the process, but notwithstand- ing the fact that natural sedimentation has its limitations and is a failure in the regard stated it has its proper and necessary place in the art of water clarification. Circulation. Phenomena which are apparent in a large set- tling-basin may be absent in an experimental plant because of the impracticability of duplicating in a small way all the condi- tions which affect the circulation of water in a large settling- basin. Many of the author's observations recorded in this chapter were made while conducting experiments on a small scale and while supervising the operation of the Quindaro settling-basin of the Kansas City, Missouri, water-works. A plan of the Kansas City basin is shown by Fig. 20. It is about 20 feet deep at the division walls, and as originally designed by G. W. Pearson, division No. I of the basin was the receiving-basin of the raw water. The water entering the basin through a rising pipe and a well about 4 feet high, impinged against an inverted conical deflector which caused the water to spread horizontally in all directions. In 1899 the influent pipe was extended across divi- sion i and was made to deliver the raw water into a conduit in the wall separating divisions i and 2, through which it -flowed to openings at the foot of the vertical wall of the straight side of the basin and discharged laterally into division 2. The object of this change was to make division i a clear- water basin, as it had become too small to work successfully as a raw-water basin when the rate of delivery into it exceeded 6 to 8 million gallons 128 WATER-SUPPLIES. a day. Modifications were also made of the manner of passing the water from one division of the basin to another at about the same time as the change above noted was made. As origi- nally designed the water passed from one division of the basin to another through conduits and openings constructed in the division walls, the water entering openings near the top on one side of a division wall and discharging into an adjoining basin Round ^ 2-1 tf \Anchor Rod SECTION OF BUTTRESS OF WALL BETWEEN BASINS 3 AND 4 FlG. 21. through similar openings at the foot of a division wall. The water 'circulates on the modified plan by overflowing a portion of a division wall. The water from division 2 flows into division 3 over a weir in the division wall 133 feet long. In a similar man- ner the water passes into division 4 from division 3 over a weir in the wall between divisions 3 and 4, 185 feet long, shown in sec- tion by Fig. 21. From division 4 the water enters division i RIVER-WATER SUPPLY. 129 through a conduit in the straight side wall. Provision is also made for delivering the influent water into any one of the three large divisions while some one of these divisions is temporarily out of service. Plates XVI, XVII, and XVIII show an eleva- tion of the weirs in the division walls. The effluent well remaining as originally designed is a con- duit in the bottom of the circular wall between divisions i and 3, extending from the inlet tower to the large buttress of the cir- cular wall between divisions i and 4. It connects with divi- sions i, 3, and 4. . In operating a settling-basin on the displacement plan the influent water should be delivered horizontally near the bottom of the basin in order to avoid as much as possible a tendency to upward vertical motion and to favor a dispersion of the enter- ing water, conforming to a temperature contour. The entering water when thus introduced distributes laterally over the basin without rising to the surface. This fact has been observed upon numerous occasions by comparing samples of water from various depths and from various portions of the division receiving the raw river-water. For a considerable depth the turbidity is about uniform, then slightly increases, and finally there is a decidedly abrupt change from turbidity to intense muddiness. The variations of the depth of the mud plane appear uniformly distributed throughout the entire division receiving the raw water, except when the entering water is abruptly de- flected upward near the delivery openings, where the heavy sediment is chiefly deposited. Below this mud plane there is a thick fluid mud which apparently increases in density until the solidified deposit on the bottom is reached. As the deposit accumulates, the level of the mud plane rises and eventually mud streaks the overflow into the succeeding basin, indicating the approach of cleaning time. However, the working life of the raw-water division may be somewhat prolonged by discharging a portion of the liquid mud through the drain. The working of a settling-basin on the displacement plan continues satisfac- torily until the basin becomes foul or overtaxed, or until vertical currents are induced by a sudden and injudicious increase of the rate of delivery of river-water into the basin, or until a rapid 130 WATER-SUPPLIES. u n U RIVER- WATER SUPPLY. WATER-SUPPLIES. RIVER-WATER SUPPLY. 133 building up of the heavy sediment near the influent openings deflects the entering water abruptly upward. The author's attention was early directed to the theory of displacement as producing the continuous flow of water from one division of a settling-basin to another by observations of the tendency of the water entering a settling-basin to stratify accord- ing to a temperature contour. Turbidity observations made of the raw-water division of the Kansas City settling-basin showed that there existed at the time of one series of observations but slight difference in the degree of turbidity for the first 13 feet in depth and almost a uniform degree of turbidity for the first 5 feet, even over the influent apertures. The transition from a state of turbidity to one of dense muddiness was sudden and pronounced below the 13-foot level. Other observations of the same kind at different times demonstrated similar conditions with the mud plane at a quite uniform level, though of a varying depth from week to week. It was also observed when a division of the basin was empty for cleaning that the solidified fine mud was quite uniformly distributed over the bottom, sometimes exhibiting a stratifica- tion of different shades, while the heavy sediment was found to form a comparatively high embankment in the vicinity of the inlet opening. When pumping machinery is employed to deliver the raw water into a settling-basin a thoughtless attendant will occa- sionally speed the pumps unduly, with the effect of abruptly chang- ing the rate of delivery and of unbalancing the adjustment of lateral circulation. The increased energy thus communicated to the water often induces convection currents which give an upward circulation of water above the mud plane established by the previous regime of pumping and circulation, with a cor- responding infusion of intensely muddy water into the partially clarified water of the upper depths of the basin. The convection currents readily climb the faces of the enclosing walls and slopes of a basin and diffuse laterally therefrom. The tendency of water to stratify is very marked during the summer and autumn seasons when the temperature of the air is either comparatively steady or subject to gradual change. 134 WATER-SUPPLIES. Then the upper layers of the water in the basin reach a tem- perature above that of the river-water, and the entering river- water, responding to the law of gravity, naturally seeks the lower depths and a lateral distribution in the basin corresponding to some temperature contour. Doubtless this stratification of the water accounts for the existence of the mud plane referred to on preceding pages. At other seasons, particularly the early spring and the early winter months, certain natural causes serve to break in upon the normal working condition of the settling-basin, producing pronounced convection currents which are locally termed ''boil- ing." The appearance of this boiling is not due to any sudden alteration of the regime of operating the basin, as all divisions of the basin may be similarly affected, though perhaps not in the same hour or day. Temperature observations made of the water in the Kansas City settling-basin revealed tempera- ture conditions at different depths of the basin indicated by Table IV. TABLE IV. Date. Depth below water-surface in subsiding-basin in feet. B _0 v- I* t_ t> > s i' 2' 3' 4' s' 6' TO' II' Temperatuie in degrees Fahrenheit. June 2 1808 82 84 87 76 54 3 36 82 82 82 81 8o 84 72 SoJ ~-J 00 00 00 H OJ K) O MH 80 5 2 Oo 00 00 ON 80 72 Tulv 2C, 1808. . Aug 10 1808 Sept. 8, 1898 Aor 14. 1800 Jan. 20, 1900 Jan 26 1900. . . In every instance noted in the table except that of January 2oth, the temperature observations were made with the basin in a stable working condition and unaffected to any material degree by convection currents. On January 15, 1900, the divi- sions all exhibited pronounced convection currents, particularly division 3. In division 4 much hydrate of alumina boiled up to the surface of the water. On January i6th the convection currents had nearly abated. At that time the surface tempera- R1VER-WA7ER SUPPLY. 135 ture was 35 degrees, and the temperature was 36 degrees at a depth of 15 feet. On this date the hydrate of alumina in divi- sion 4 had largely disappeared. On January 2Oth the boiling action was resumed in division 3 and was clearly visible along the wall separating divisions 3 and 4, along the west embank- ment, and in various other parts of the division. A thin skin of ice which had formed over the basin during the preceding night emphasized the appearance of the convection currents as they were revealed through the ice. The ascending mud and gray hydrate of alumina seemed to rise with a rotary motion and after contact with the ice rolled away radially in a manner resem- bling the rotating smoke and steam blown from a locomotive stack as it gradually rises, expands, and disperses through the atmosphere. Temperature observations made on that date at the surface and 15 feet below the surface revealed a uniform temperature of 36 degrees. Doubtless the same tendency towards stratification exists in the water as in the atmosphere. When a break of the stratifi- cation ensues, the vertical currents are similar in both fluids, though of course less violent in water because of its greater weight and inertia. Numerous temperature observations of the kind indicated in Table IV were made at various times, but all seem to indicate that a fall of temperature of about two degrees or more between the surface-water and that about 10 feet below is necessary to pre- serve a stable working condition of the water in a basin operated upon the displacement method. Convection currents develop frequently in the spring of the year as the ice in the river breaks up and moves out, but before the ice in the settling-basin has entirely melted, as well as in the late fall or early winter when new ice is forming or the surface of the water in the basin becomes chilled, and in this regard the movements of the water resemble the seasonal upsetting of the water in a storage reservoir or in natural lakes. When vertical circulation is in progress the upheaval of sediment from the deeper portions of the water of a settling-basin temporarily emphasizes the difficulties of water clarification by sedimentation. Even a deep basin, although 136 WATER SUPPLIES. advantageous in several respects, may be no protection from temperature convection currents. The use of deep settling- basins has been discouraged because of the expense of con- structing high masonry walls. This objection can now be met in a measure at least by the use of reinforced concrete. Surface currents, usually pronounced when the water passes off a weir in a division wall at the water-level of an adjoining basin, may be prevented by a curtain of planks set several inches from the face of the division wall and projecting several feet beneath the surface of the water, thereby serving to improve cir- culation and to assist clarification. Baffles have been introduced in small subsiding basins to direct the circulation of water, but as simplicity of design and opera- tion is desirable in sedimentation basins intended for operation on a large scale baffles complicate the operation and add con- siderably to the expense of construction and maintenance. The swinging motion of the water as a body is still another form of circulation which seems to be entirely independent of those herein described. The motion is so slow that evidence of it is to be found rather in the relative clearness of the water in different portions of any division of a basin than in any well- defined visible movement. In the Kansas City basin the clear- est water to be found in either division 3 or 4 is in the corner of the divisions marked on Fig. 20 "clearest water," opposite the outside or boundary walls of the basin. In this case the water after falling from the weir seemed inclined to swing toward the boundary walls and to clarify as it receded from the weir and finally to reach the highest degree of clearness when it had reached the location of the zone of the clearest water above alluded to. The line of separation of the clearest water in the basin from that discharged from the weir is generally very decided and dis- tinct. What influence the peculiar form of the basin referred to may have in producing this swinging motion has not been investigated, but there is every reason to believe similar con- ditions would exist in a rectangular basin were the weirs of no greater fraction of the length of the division walls than they are in this basin. It is quite probable, however, were the weirs to extend the whole length of a division wall the swinging RIVER-WATER SUPPLY. 137 movement of the water as a body would become less ap- parent. It cannot be assumed that the basin is effective only for a width equal to the length of a weir in a division wall and that the water is dead in the corners of a basin beyond the ends of a weir, for it has been observed that a change of turbidity in the water falling from a weir is followed by corresponding but progressive change in all parts of the division receiving the water, even in all the corners, showing that all portions of the basin are effective. The corner of "clearest water" is the last, of course, to fall under the influence of any change, but none the less sure of showing the degree of change in the division as a whole. Insistence upon a symmetrical or geometrical figure of a settling-basin seems unnecessary, and in fact is frequently impossible owing to topographical or land boundary consider- ations, nevertheless capacity to the fullest extent is serviceable or can be made serviceable by proper design and manipulation of the operating details. Coagulation. We have already pointed out the inefficiency of natural sedimentation to properly clarify water of a detrital river. The condition of the subsided water when the beneficial effect of natural subsidence practically ceases is variable, depend- ing upon the amount of silt or finely divided clay the river-water may carry in suspension. So great is this variation that exposure of a raw river-water to a stated number of hours of natural sedi- mentation is found to show a turbidity variation of considera- ble range. For instance, twenty-four hours' natural sedimen- tation will afford a much clearer water at some seasons of the year than at other seasons and during some periods of the same season than during other periods. So deficient has natural sedi- mentation been found that the aid of a coagulant is necessary to produce even a fair degree of clarification on many occasions. The amount of coagulant used varies with the degree of turbid- ity of the naturally subsided water. Thus far the sulphate of alumina has been used most extensively to facilitate clarification. Clarification of the water with the aid of sulphate of alumina is both a chemical and mechanical process, and as such it is now so well understood as to scarcely require explanation in 138 WATER-SUPPLIES. this chapter were it not that the various allusions herein made seem to require some general explanation. The use of a coagulant is for the purpose of gathering together into small masses the very fine particles of silt and clay which of themselves are so light and fine as to resist natural subsidence and to thereby hasten their fall through the water. The coagulant for successful use must be harmless in its effect upon the water treated, leaving its wholesomeness unim- paired, and also cheap enough in the market to be available to any community which by force of circumstances may have occa- sion to use it in the clarification of the water-supply. The sul- phate of alumina, when judiciously used, has been found to answer the requirements successfully. Its properties and its effect upon turbid waters have long been known. As manufac- tured, it is a salt of aluminum composed of about 16 to 18 per cent of alumina, about 36 to 37 per cent of sulphuric acid, and about 44 to 46 per cent of water, together with a small percent- age of impurities like oxide of iron, in a chemical combination similar to a combination of sulphuric acid with lime or mag- nesia. In a salt properly made, there should be no free sul- phuric acid. It is highly soluble in water and therefore readily made into a solution of any degree of strength up to one of com- plete saturation of the water. The chemical affinity of the constituents of this salt is com- paratively weak and is readily broken in the presence of other solutions of mineral salts, such as the bicarbonate of lime and magnesia, and made to assume new chemical combinations of a more stable character. In fact its use depends upon the pres- ence in the water to be treated of a mineral salt in solution ca- pable of new chemical combinations with the applied solution. Many natural waters contain abundance of lime and magnesia, the constituents of limestone, which are held in solution by carbonic acid, and with these salts the dissolved sulphate of alumina readily enters into combination, forming sulphate of lime or magnesia, free carbonic acid, and hydrate of alumina. The sulphate of lime or magnesia and the carbonic acid remain dissolved in the water, while the hydrate of alumina, being insoluble in water, remains a floating though finely divided solid and RIVER-WATER SUPPLY. 139 thus completes the essential chemical part of the process of coagu- lation. The presence of the carbonates of lime is characteristic of natural waters in limestone territories and is familiarly termed "temporary hardness" or alkalinity, the qualifying term "tem- porary" being used to distinguish the portion of the lime pre- cipitated by boiling, the boiling having the effect of releasing the carbonic acid as a gas. Natural waters which are soft or possess little or no alkalinity must first be treated with lime water, a solution of carbonate of soda, or some mineral base of this character before the sulphate of alumina solution is introduced. The sulphate of lime and magnesia is a usual constituent of natural waters and represents the permanent hardness of water. In contrast with the temporary hardness,* the perma- nent hardness is not affected by boiling. Carbonic acid as found in natural waters is acceptable, it is desirable in a drinking-water and is present in natural waters in varying amounts. It should be observed that the use of the sulphate of alumina introduces no new chemical compounds in solution in the water treated; practically its only effect is to transfer a portion of the mineral water in solution from a state of temporary hard- ness to one of permanent hardness, but usually the amount of mineral thus affected is small in comparison with the total amount of hardness naturally present in the water treated. Of course no undecomposed sulphate of alumina should remain in the water after treatment and does not remain when the coagulant is in- telligently used. The hydrate of alumina formed by the chemical combina- tion just described is a sticky insoluble mineral in a finely divided state when freshly formed, but gradually the small particles unite as they circulate through the water, collect the fine sedi- ment, and finally subside in small masses. This constitutes the mechanical part of the process of coagulation. A common practice is to introduce the coagulant solution into the raw water as it is being delivered to the settling-basin. In cases where the water is delivered to the basin by pumping, 140 WATER-SUPPLIES. a small by-pass pipe is connected, with the main delivery-pipe and with a pressure- tank. Dry sulphate 'of alumina is put into the tank and the top bolted on. Water from the deli very -pipe is then turned into one end of the tank, dissolving the sulphate of alumina as it circulates through the tank; the solution pass- ing out at the opposite end of the tank is returned to the deli very -pipe. This method of coagulation is exceedingly faulty and crude, as it gives a very irregular distribution of the coagu- lant. Introduced in this manner the coagulant has apparently little or no effect in clarifying very muddy water because the hydrate of alumina is either absorbed by the large amount of organic matter usually present in muddy water or becomes entangled with the heavy sediment as it subsides naturally and goes to the bottom of the basin without effect on the fine sediment. Several years ago the author made a few simple analyses to determine the loss of coagulant when introduced into the raw Missouri River water, and to determine a ratio of the alkalinity of the water consumed in the process of coagulation to the amount of coagulant used in the operation. The method employed in these experiments was to collect a sample of the raw river-water as it passed through the basin delivery-pumps and to treat imme- diately one portion of this sample with a definite amount of coagulant solution of known strength, and another equal por- tion of the same sample after removing the sediment by filtra- tion with an equal amount of the same coagulant solution. After treatment and subsidence, an aliquot part of each sample was siphoned off and its alkalinity determined and compared. The difference of the residual alkalinity of the two samples respec- tively was taken to represent the equivalent of the coagulant absorbing capacity of the sediment and was reduced to grains per gallon by dividing it by the ratio of the alkalinity consumed in the treatment of the filtered sample to the known amount of coagulant in grains per gallon used in the treatment. The results are compiled in Table V. In the experiments indicated by the results collated in Table V an effort was made to keep a little within the range of the total coagulant decomposing capacity of the river-water. A proper RIVER-WATER SUPPLY. 141 TABLE V. Date. 1900 Description of sample. Suspended matter in river-water, parts per million. Sulphate of alumina, grains per gallon. Alkalinity. Ratio of alkalinity consumed to coagu- lant used, grains per gallon. Coagulant absorbed by mud. grains per gallon. Before treat- ment. After treat- ment. Feb. 5 3 20 5 230 53-5 8.6 9 3 26.1 25 8. 7 " 21 3 23.2 255 50 9.0 March 2 3 23.2 230 27-5 8. 7 5 3 23.2 230 3 8.6 " 7 Muddy 740 " R / Muddy 17.4 175 43-5 o \ Filtered 17.4 35- 8.0 ,, f Muddy 1220 !5-5 145 52-5 9 \ Filtered i5-5 25.0 8-4 3-3 44 / Muddv 2315 ii. 6 120 37-5 I C 1 Filtered n. 6 25.0 7.8 1.6 " 12 / Muddy Filtered 2520 ri.6 ii. 6 125 65.0 35- 7.8 3-8 ,. f Muddy ii. 6 120 55 o 3 1 Filtered ii. 6 35- 7-3 2.7 tl / Muddy 200O n. 6 115 45- 14 \ Filtered n. 6 25 7-7 2.6 4 , Muddy n. 6 II2.5 55 J 5 f Filtered ii. 6 2 5 7-5 4.0 Muddy 1500 ii. 6 Il6.5 55 I 7 Filtered ii. 6 3 7-5 3-3 ,, Muddy 1160 ii. 6 122.5 5 *9 \ Filtered ii. 6 37-5 7-3 1 7 " 20 f Muddy ii. 6 I2 7-5 55 1 Filtered ii. 6 22.5 9.4 " 21 f Muddy 2520 ii. 6 i3 6 -5 67-5 ii. 6 " 00 / Muddv ii. 6 I 5 75 2 2 t Filtered ii. 6 52.5 8.4 2.7 / Muddy 14-5 i5 52-5 3 t Filtered 14-5 40 7 6 1.6 " 24 f Muddy 1 Filtered 5 10 14-5 14-5 150 47-5 40 7.6 i .0 44 f Muddy i75> 14-5 160 90 29 1 Filtered 14-5 5 7.6 5-3 April 28 J Muddy \ Filtered 3420 14-5 14-5 125 75 22.5 7- 1 7-4 " 30 f Muddy \ Filtered 14-5 14-5 122.5 50 7.2 4-5 Average 7-9 test showed that no undecomposed coagulant remained in the water after each treatment. What difference there might have been in the relation of the residual alkalinities in each set of experiments had a small amount of coagulant been used was 142 WATER-SUPPLIES not determined. The object in view was simply to confirm pre- vious observations, made during the actual working of a large settling-basin, of the ineffectiveness of introducing the coagulant directly into the raw river-water heavily burdened with sedi- ment. The ratio of the alkalinity consumed by the coagulant to the number of grains of coagulant used in the treatment of the water agrees fairly well in all instances except that for March 2ist, which ratio is omitted in determining the average ratio of 7.9. It is perhaps practically correct to use a ratio of 8 to conveniently determine the capacity, of the Missouri River water at least, to decompose sulphate of alumina, and in such computations as follow this ratio has been used. The ratio is only approximated, however, when the amount of coagulant used in treating the water approximates the total coagulant decomposing capacity of the river-water, as is illustrated by the following table. The water in the subsiding basin referred to above on January 20, 1900, having an alkalinity of 210 parts per million, when treated with different amounts of sulphate of alumina showed a variable ratio of alkalinity consumed to the amount of coagulant used in the treatment. The results were verified by analyses on several succeeding days. TABLE VI. Amount of sulphate Alkalinity after Ratio of alkalinity of alumina in grains treatment, parts consumed to per gallon. per million. coagulant used. 5-8 146 II . o 8.7 122 IO.O ii. 6 102 9-3 14-5 80 9.0 17.4 63 8.5 20.3 36 8.1 23.2 26 7-9 26.1 IO 7-7 The results of the experiments recorded in Table V not only show the extreme wastefulness of the practice of introducing the sulphate of alumina into a raw water heavily charged with sediment, but also offer another reason for the unsatisfactory results to be derived from the fill-and-draw method of oper- ating a settling-basin which admits only of the coagulation of RIVER-WATER SUPPLY. the raw water as it is delivered into the basin. An attempt to use an amount of coagulant in the clarification of a very muddy water which provides for the losses above pointed out and in addition reaches and coagulates the fine sediment which gives persistent turbidity to a water after natural sedimentation entails a prohibitive expense in clarifying water on a large scale. The most effective time to introduce the coagulant is after the water has passed through a period of natural sedimentation. The length of this period varies with the character rather than the amount of the sediment contained in the raw water and with the season of the year and should scarcely exceed twenty- four hours in length. A coagulant introduced into the Missouri River water after about 83 per cent of the sediment had been disposed of by about twenty-four hours' natural sedimentation has proven very effec- tive. The amount of coagulant required for clarification is found to vary with the turbidity after the twenty-four-hour period of natural sedimentation, but not necessarily with the amount of sediment in the raw water. In this connection and as a matter of illustration it may be of interest to tabulate a few analyses indicative of the character of Missouri River water and of the amount of sulphate of alumina that is required for clarification. The alkalinity recorded in the second column of Table VII is a measure of the coagulant decomposing capacity of the river- water expressed in parts per million, and in column 4 the same capacity is expressed in grains per million and is found by dividing the alkalinity by 8, the ratio derived from Table VI. The table embraces the period of the least as well as the greatest alkalinity of the river-water for the interval of a year. The large surplus of alkalinity beyond that required for chemical union with the sulphate of alumina with which the water was treated affords conclusive proof that no undecomposed sulphate of alumina could have remained in the clarified Missouri River water of that year. An absence of turbidity observations in the table is notice- able and the observations may accordingly be considered incom- plete when viewed from a scientific standpoint. A few tur- i 4 4 WATER- SUPPLIES. TABLE VII. Date. In parts per million. In grains per gallon. Alkalinity, city water parts per million. Alkalinity of river-water. Suspended matter, river-water. Coagulant decomposing capacity, river-water. Coagulant used in sub- siding-basin. Apr. 23, 1899. . 535 24 " .. 3584 26 " . . 126 349i 15-8 2.18 120.75 27 " 128.6 2787 16.1 1.9 112.9 28 " . . II5-5 14.4 1.9 May i 301-3 2 " . . 120. 7 5279 3 " 131.2 16 .4 1-7 5 123.4 4221 15-4 i . 7 17 . . 126 15-8 i-55 19 126 2446 15.8 1.82 22 " . . 113.9 523 14.2 2.76 1 . . IIO. 2 13-8 2.40 25 " 2530 2.83 June 10 ; . . 128.6 8064 16.1 0-95 IIO. 2 19 '* . . 120.75 5756 15. i 1.62 July n " . . 120. 7 3633 15. i 0.95 IIO. 2 28 " . . "5-5 3418 14.4 o .69 Aug. 7 " .. 107 .6 13-4 1.19 103 . 7 8 -;.. 2420 I . OO 10 " . . 105 2340 13. i 0.75 103 . 7 13 " 105 13 . i 1.30 22 ; . . 120. 7 1735 15 . i o. 96 Oct. 13 159-3 19.9 0.37 21 " . . 155 19.4 o-53 150 Nov. i " . . 19.7 0.42 155 6 " .. 660 0-44 8 ' ... 160 20 0.41 J 57-5 Dec. 18 " . . 0.23 170 21 " .. 2IO 50 26 0.22 I77.S 30 " .. 240 3 O.O 225 Jan. 3,1900.. O.O 265 5 " .. 275 34-4 O.O 8 " .. 275 34-4 0.0 9 260 120 32.5 0.23 ii 245 30.6 O.42 12 " . . 265 370 33-i 0-45 *3 o . 55 25* 15 " 2IO 8 3 26.0 0-75 235 16 " .. 215 26 . 9 o. 76 227 18 " .. 215 650 26 .9 o.45 230 20 " . . 2IO IOO 26 .0 0.43 227 22 " . . 195 24-4 o. 50 2IO 24 " . . 197 490 24.6 0.50 2IO 26 " .. 192 515 24 o o-44 205 27 ; .. I9O 23-8 0.42 192 29 ' ... 205 25-6 0-45 198 31 " ' 225 28.0 0.46 195 RIVER-WATER SUPPLY. TABLE VII (continued). 145 Date. In parts per million. In grains per gallon. Alkalinity, city water, parts per million. Alkalinity of river-water. Suspended mater, river-water. Coagulant decomposing capacity, river-water. Coagulant used in sub- siding-basin. Feb. i, 1900. . 222.5 2 7 .8 o-39 200 3 225 28.1 0.21 217-5 5 230 28.8 0.0 22O 6 242-5 3 30-3 0.0 225 9 252.5 30 31-6 240 12 255 3 31-9 250 14 255 3 31-9 252.5 19 260 30 32.5 255 21 255 3 31.9 o.o 257-5 Mar. 2 2 3 3 28.8 O. 22 240 5 22 5 3 28.1 0.24 232.5 7 172.5 740 21.6 0.66 230 8 175 21.9 0.74 2IO 9 145 1220 18.1 0.77 195 10 I2O 2315 15.0 1.28 175 12 I2 5 2520. 15-6 2.34 155 13 120 15.0 3.61 135 14 "5 2000 14.4 2.84 II7-5 15 II2.5 14.1 2-43 102 . 5 16 I2O 15.0 .89 97-5 17 Il6.5 I5OO 14.4 .72 IOO 19 122.5 1160 83 '5 20 I2 7.5 15 .9 .64 105 21 136-5 2520 17.1 .61 107-5 22 150 18.8 .66 i7-5 2 3 150 18.8 52 125 24 152 510 19.0 43 122.5 26 150 18.8 .41 127-5 2 9 160 175 20. o 2.24 142.5 bidity observations were made in the laboratory, but were dis- continued for the reason that turbidity observations of the water in the basin itself offered a better guide for the attendant in constant charge in proportioning the strength of a day's coagu- lant solution. An indication of a progressive increase of tur- bidity in division 3 of the settling-basin was followed by an in- crease of the amount of coagulant used until the increase of turbidity was checked, then the strength of the coagulant solution was reduced accordingly as the decrease of turbidity became apparent in division 3. The variation of turbidity in either division 3 or 4 of the basin was very apparent to a close observer of the daily work- 146 WATER-SUPPLIES. ing of the basin chiefly in a triangular patch of water extend- ing from the inner end of the weir in either division wall toward the outer wall of the basin, as indicated on Fig. 20. There was usually a rather sharp line of division between the recently coagu- lated water and that of the water which had undergone partial subsidence after coagulation. A tendency of this line of division to move away from the weir invariably indicated a gradual increase of turbidity, and if this tendency remained unchecked by the use of too small an amount of coagulant the line of divi- sion would gradually encompass a larger and larger patch of the water and finally fade almost entirely in a cloud of general turbidity. Thus an attendant making numerous daily observa- tions of the appearance of the water in the several divisions and having presented to his eye the relative position of the line of division between the recently coagulated water and that par- tially subsided as the line advances with the general swing of the water as a body or retreats toward the weir, and having fixed objects beneath the surface of the water in the clear- water basin by which he could instinctively compare turbidities of succeeding observations, could not fail to detect slight variations of turbidity and to act accordingly day by day in proportion- ing the strength of the coagulant solution. While this fact and these circumstances account for the absence of a turbidity record in Table VII, they are not to be taken altogether as a justification for a neglect to make frequent laboratory measure- ments of turbidity not only as a matter of record but also as a help in the economic use of a coagulant. But however this may be it must be acknowledged that the laboratory observations cannot supplant those observations which the attendant can and must make of the working condition of a settling-basin from time to time as he moves along the division walls and sees the operation from different points of view. Instinctively his judgment as to the variations in the management of the basin is largely governed rather by his general observations of the working of the basin itself than by laboratory measurements of turbidity. The laboratory measurements enable him to record the facts or circumstances which influence his judgment. Observations of alkalinity are the only sure guide to the RIVER-WATER SUPPLY. safe use of a coagulant when the raw water is comparatively soft or of low alkalinity contents or during periods of floods, par- ticularly flashy floods of rivers having naturally . hard water, for then the alkalinity may run abnormally low at a time when there arises the greatest necessity for the use of the coagulant. The coagulant decomposing capacity of the raw water should always be known to be sufficient for the complete decomposition of the amount of coagulant required for clarification, and when at critical periods the alkalinity runs too low to completely neu- tralize the coagulant, then the requisite amount of alkalinity must be supplied artificially by the introduction of lime-water or a solution of carbonate of soda or other alkaline base. TABLE VIII. CONSUMPTION OF SULPHATE OF ALUMINA IN THE KANSAS ClTY SUBSIDING-BASIN IN GRAINS PER GALLON. c >c & 1899. 1900. Apr. May. June. July. Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. i 36 78 0.69 -93 I . OO 0.48 0.46 0.42 -53 0.00 0-39 0.21 1.67 2 .09 .72 0.72 i .06 0.69 o-35 0.42 0.42 o-54 0.00 0-37 0.22 1.42 3 .14 .70 0.65 0.99 o-75 -37 0.42 0.44 0.30 o.oo 0. 21 o. 25 1.24 4 .14 56 -93 54 o. 69 0.44 0.42 0.44 0.79 o.oo .OC 0.26 5 .14 .70 0.83 J 3 1.04 0.36 0.44 0.42 0.98 o.oo o.oc 0.24 1.67 6 03 .78 -93 .00 1.19 o-37 0.44 0.44 0.87 o.oo o.oc 0. 2C 1.64 7 43 7 1 0.86 .02 1.19 -35 0.42 0.42 o, 60 o.oo o.oc o.6C : -37 8 36 7i 0.89 .00 i .00 0.38 0.56 0.41 -43 o.oo 0. OC o.7j : . o 9 63 83 0.96 .OO o-73 0.42 0.48 0. 20 -55 0.23 0. OC 0.77 i .64 10 .68 56 -95 0.99 -75 0.50 o.45 0.21 o. 29 0.41 0.00 i .28 2 -3 ii 43 73 .70 -95 0.81 0.42 0.41 0. 20 0.52 0.42 o.oc 1.61 1.71 12 7i .82 .70 0.91 -93 0.41 -39 0.24 0.25 0.45 o.oo 2-34 1.8 *3 .98 .70 55 0.90 1.30 0.41 -37 0. 2O 0.24 o-55 o.oo 3-6i 1.86 14 93 63 .72 o. 96 I . 12 0.42 0.36 o 70 o. 20 0.49 o.oc 2.84 1.9 15 2.28 49 33 .06 0.96 0.46 -39 0.42 0.24 -75 o.oo 2-43 1.71 16 2-37 55 . 12 .24 o 96 0.44 0.38 0.77 O. 22 0.76 o.oo .89 !-7 17 2.19 55 43 13 0.69 0.48 o-73 0.41 o. 25 0-59 o.oo ,72 18 .80 36 . 22 13 o . 96 0.44 0-34 0-44 0.23 0-45 O. OO 93 19 .70 .82 .62 .04 o 89 0.44 o-35 37 0.23 0.44 o.oo 83 20 .78 73 39 5 r -!3 0.50 o-53 0,47 0.25 0-43 O . OO .64 21 .78 .96 39 .04 I , 10 0.42 -53 0.47 0. 22 0-54 O . OO .61 22 .67 2 76 34 0.78 o . 96 0.42 o. 56 o 49 0.38 0.50 0,21 .66 2 3 93 2 .40 57 0.89 0.82 0.48 -55 0.23 0.32 0.50 0.25 5 2 24 2-34 3.89 .01 i .04 75 o. 50 o. 50 O 20 o-39 0.50 0'. 21 43 25 2.17 2.8 3 .41 0.72 0.72 0.46 0.41 0,23 o.45 0.47 . 22 47 26 a.iS 2.69 13 o-75 0.78 0.44 0.41 0.30 0.29 0.44 o 25 .41 27 I. 9 C 2.28 .16 I .00 2 23 0.42 0.41 o 24 o.oo 0.42 . 22 .46 28 I. pc 1.6 3 . 12 0.69 0,85 0.44 o-39 o. 24 0.00 0.49 o. 24 36 29 I.QC J-39 0.88 0.72 0.72 -39 0.46 o. 46 00 0.45 2.24 30 i.8 -93 1.16 0.89 o 46 0.41 0.42 0-51 00 0.42 i.5c 31 0.72 o . 76 o . 50 0.42 . OC . 4 e 1.42 148 WATER-SUPPLIES The amount of coagulant used and the distribution through- out the year for the clarification of the Missouri River water is shown in Table VIII. Upon platting the few determinations of the amount of sedi- ment contained in the Missouri River water after about twenty- four hours' natural sedimentation and the corresponding amounts of sulphate of alumina used in the clarification of the river-water as expressed in Table II and VII, the amounts of sulphate of alumina for different degrees of turbidity may be roughly approximated as follows: TABLE IX. Suspended matter in Missouri River water after about 24 hours' natural subsidence. Parts per million. Amount of sulphate of alumina required for clarification. In grains per gallon. SO O.O IOO o-5 150 I.O 2OO i-5 2 5 1.9 300 2.4 350 2.9 400 3-4 450 3-8 500 4-3 55 4.8 600 5-3 The table indicates that no coagulant is required when the raw water contains about 50 parts per million of sediment. In this condition the water is acceptable for general use and may be even clearer than the clarified water will be found occasion- ally during seasons of freshets, usually from March to August, inclusive, when the turbidity of the clarified water has been found to range from 50 to 100 parts per million in a settling- basin of about four times the amount of the daily consumption. A basin of relatively less capacity requires the use of relatively more coagulant than that expressed in Table IX. In the practical use of a coagulant it is most desirable to use a solution of constant volume but of variable strength, depending upon the turbidity of the water to be treated. The volume of the solution cannot be definitely stated, as it depends RIVER-WATER SUPPLY. 149 upon the character of the apparatus used in introducing it into the water-supply and may vary somewhat with the character of the water to be treated. The coagulant solution should be delivered under constant head into the water to be treated by some other method than that of direct-pressure pumping. It is best to provide a tank at sufficient elevation to give the requisite head of discharge and to deliver the solution into the tank by means of a pump connected with the mixing-tanks. A uniform level can be maintained in the tank by providing an overflow-pipe so con- nected as to admit of a return of that portion of the solution to the mixing-tank which is pumped in excess of that required for use. The delivery of the solution should be controlled by a valve suitably calibrated or a similar measuring device. A long line of iron pipe leading from the regulating-tank to the point of distribution is especially objectionable, as its capacity will speedily become seriously impaired by heavy accumulations upon the interior walls. It is far better to use brass or lead- lined pipe for the delivery of the coagulant solution. The lead is not affected by the solution and less readily clogged by deposits. The required capacity of the coagulant apparatus depends very much upon the local conditions and volume of the water to be treated. There should be at least two mixing-tanks, each holding sufficient solution for one day's use. A tendency of the solution to stratify in the mixing-tanks should be avoided by providing and using an agitator to give the solution occasional circulation. When weirs are employed to pass the water from one divi- sion of a settling-basin to another, the coagulant solution can be very effectively distributed through pet-cocks spaced 3 to 4 feet apart in the coagulant pipe extended along the weir. The solution discharging from the pet-cocks enters the water as it flows in a thin sheet across the weir and becomes thoroughly distributed by the circulation of the water, particularly if the water drops several inches from the lip of the weir. Fig. 22 illustrates a method of distribution through pet-cocks. Taken as a whole, the process of water clarification by the combined process of natural sedimentation and coagulation is a WATER-SUPPLIES. decided improvement over that of natural sedimentation alone, if for no other reason than that there ensues a greater uniformity of the general appearance of the water throughout the year. Moreover, by an intelligent use of a coagulant a rapid transition from a slightly turbid water to one of intense turbidity can te prevented. The methodical use of a coagulant to> promote and accelerate sedimentation arose at first simply because plain or natural sub- Coagulating Pipe- Basin No. 2 100'Weir /* Cocks From Puii.p House -X Cocks Basin No. 3 | Kiev. . 1 Elev. 19.5 sidence failed to give satisfactory results. A way was thus opened of improving the water-supply without sacrificing property already constructed and serviceable. It was a logical step in a fuller development of the usefulness of the settling-basin, but nevertheless not a concluding step in the art of water clarifi- cation. The process fails to remove all the natural turbidity of a river-water and leaves suspended in the partially clarified water a portion of the decomposed coagulant. Even a sample of water from the clear- water division of the large settling-basin wherein objects several feet under water are discernible will RIVER-WATER SUPPLY. 151 upon standing a few hours disclose small clots of the hydrate of alumina. Convection currents, which are usual in the spring and fall of the year in a large settling-basin, never fail to cause an upheaval of the hydrate of alumina. On such occasions, when subsidence is sluggish, the amount of hydrate appearing in the clear -water basin is considerably increased. Although there is no substantial evidence that the compara- tively small amount of the decomposed coagulant which thus reaches the water-supply is deleterious, still it is desirable that ah 1 of the suspended products of coagulation should be removed from the water before reaching consumers. This is all the more important because the particles of the coagulant which thus pass the clarification works collect in the water-pipes of the distributing system where the consumption is usually small and occasionally receive a complete stirring up when there is a sud- den and abnormal draft. On such occasions the consumers are liable for a brief period to receive water quite heavily charged with the hydrate of alumina. The author noticing this experimented a little by drinking every third day for a period of about a month a small goblet (100 c.c.) of clarified Missouri River water immediately after treatment with sulphate of alumina solution in proportions vary- ing from 1 1. 6 to 23.2 grains per gallon with no noticeable effect. The only precaution observed was that the dose of coagulant was somewhat less than the coagulant decomposing capacity of the river-water. The experiment was simply made to for- tify a position to meet any criticisms which might honestly arise on the part of any consumer who might question the safety of using the coagulant. The occasion never arose, however, to advance the experimental argument, as the only consumer who seriously objected to the use of the coagulant filed his protest in midwinter when the river was ice-bound, accompanied by the statement that the "alum was so thick he could taste it." This objection was easily met by showing him the record that no coagulant whatever had been used for several weeks pre- ceding this discovery. This mistake was attributed to the fact 152 WATER-SUPPLIES. that the midwinter water of the Missouri River is more than double the hardness of the summer flow. The experiment probably possesses little or no scientific value in the absence of medical supervision and the brief period covered, even though the dose was concentrated, but it may be used to allay apprehension founded solely on prejudice, and in this light only can it be regarded as of value. The remarks thus far regarding the use of a coagulant apply specifically to sulphate of alumina. But so far as the principle of coagulation is concerned the remarks will apply to any coagu- lant. It is necessary, however, to refer specifically to another coagulant, the sulphate of iron, which is now used successfully to a considerable extent. The coagulating property of iron in a hydrated condition has long been known and has been frequently used in the purification of sewage. Lately the cost of manu- facture has been so reduced as a by-product of iron works that its market value is considerably less than that of sulphate of alumina and accordingly its sale is being pushed to the front by commercial interests as a coagulant. The action of both coagu- lants is similar in the regard that both require the presence of carbonate of lime in the water as a base for the chemical reaction which forms the hydrate acting as the coagulant to mechanic- ally collect the sediment and carry it to the bottom of the settling- basin in small masses. They differ, however, in the regard that the hydrate of iron is soluble in water containing free carbonic acid, while the hydrate of alumina is not soluble in the acid. Ordinarily the carbonate of lime in natural water that is available for chemical action with the sulphate of iron is there because of the presence of an excess of carbonic acid naturally present in river-water. Moreover, one of the results of the chem- ical union of this sulphate of iron with the natural carbonate of lime in water is free carbonic acid, thereby increasing the capac- ity of water to dissolve hydrate of iron. It is not therefore practicable to use the sulphate of iron solution alone, because after the resultant chemical reaction a portion of the hydrate of iron is dissolved by the carbonic acid and remains in solution in the water-supply. Later, if present in considerable amount, the iron gradually oxidizes and deposits RIVER-WATER SUPPLY. 1 53 on the walls of the water-pipes, in the service-pipes, or adheres to the surface of toilet fixtures and utensils of domestic use, or blows out through a service-pipe after a period of disuse as a rusty sediment. This difficulty is avoided in practice by treating the river- water with a solution of ordinary lime-water to neutralize the carbonic acid sometimes before and sometimes after the solu- tion of sulphate of iron is introduced. The formation of hydrate of iron is then complete because all free carbonic acid is neu- tralized by the lime-water and thereby the hydrate of iron is enabled to act to its fullest extent in coagulating the sediment. The practice of introducing lime into the river-water between the river intake and the pumps has its objection inasmuch as particles of lime collect around the valves of the pumps and may impair their operation. In one instance an engine was tem- porarily disabled by the accretions of the undissolved lime around the valves and in the valve-chambers. The presence of dissolved hydrate of iron in the water-supply may appear a small matter, knowing that iron in water for drink- ing is frequently considered beneficial, but the tenacity with which it attaches itself to toilet fixtures and domestic utensils renders it very much of a nuisance about the household, so much so that when naturally present in a water-supply in considerable amounts various communities have sought relief by constructing purification works to remove the iron. This objectionable fea- ture in the use of iron as a coagulant must be regarded and pro- visions made to guard against it in any clarification works where it is used. The further fact that the water reaches the consumer with all free carbonic acid neutralized by the use of lime is in a measure an objection which is somewhat offset by the fact that the water may be somewhat softened as a direct result of the lime treat- ment. If an overdose of lime is given the water, the supply becomes flat and insipid to the taste aside from the caustic prop- erties thus communicated to the water. It follows that the economical and safe use of sulphate of iron as a coagulant must be accompanied by a knowledge of the character of the water to be treated obtained by making a daily 154 WA7ER-SUP PLIES. partial analysis of the water in the same manner and to the same degree that is necessary for the proper use of any other coagulant. The equipment of a small laboratory at the puri- fication works for this purpose is a matter of small expense, and the necessary skill to make the test can soon be acquired by an intelligent attendant under the guidance of an experienced ad- viser to prepare the chemical reagents and to direct the method of making the daily tests. This work to be carried out success- fully must become a part of the daily routine quite as much as the firing of a boiler or the oiling of an engine. It should become part and parcel of an organized management possessing sufficient practical experience to appreciate the value and abso- lute necessity of proper attendance to technical details. Both the sulphate of alumina and the sulphate of iron add to the permanent hardness of the water treated, but usually to a comparatively small degree. Both are available for coagulating purposes, weight for weight, in proportion as each contributes to the formation of available undissolved hydrate of the respec- tive bases of aluminum and iron. Consideration of the relative cost is not to be based solely upon the market value of either salt, but should also embrace the cost of the lime needed for use in connection with the iron sulphate and the cost of maintaining the apparatus and applying the several solutions. There is no reason to suspect that the hydrate of iron will entirely subside in passing through the several divisions of the settling-basin, nor that it will be sustained in a state of suspen- sion by convection currents to any less extent than is the hydrate of alumina or the hydrate of iron in natural ground-waters. Some of the hydrate may be expected to reach the distributing - pipes and the consumers. This circumstance need be no more objectionable with one coagulant than with another so long as iron is not present in the water used for domestic purposes to an extent to color articles of white polished surfaces, cooking utensils, or to discolor tea, coffee, or articles of food cooked with it. A solution of sulphate of iron can be introduced with the most economy after the raw river-water has passed through a period of natural sedimentation unless the current of the river is so sluggish as to be unable to carry in suspension anything but RIVER-WATER SUPPLY. 155 light sediment. The wide variation of velocity, of flow between a flood and a low-water stage of a river marks a similar varia- tion in the sediment-bearing capacity of the river, consequently it is advisable to provide for a period of natural sedimentation in the construction of any settling-basin, even though it may be unnecessary for operation the whole of each year, or prepare to use a large amount of coagulant for brief periods. The conditions under which the process of coagulation must be applied are so similar, regardless of the particular coagulant employed, that the design of the settling-basin ,and the method of operating it remain substantially the same. Even the appa- ratus for mixing and applying the coagulant may be very simi- lar except that for the use of the sulphate of iron and its accom- panying solution of lime-water a somewhat larger apparatus is required. Experience has so thoroughly demonstrated the need of a coagulant in clarifying muddy river-water that even a much more extended discussion of the subject seems warranted than space here admits. An endeavor has been made to touch upon the more important considerations in the belief that they will yet receive fuller development in the practice of water clarifica- tion even with the independent use of the settling-basin. As matters now stand in the application of the process of coagulation to expedite sedimentation the least that can be said of the settling-basin is that it serves to remove the grosser impurities of muddy water and thereby prepares the water for more complete purification by some more refined process-like filtration. The most that can be said now of the settling-basin is that when constructed of a capacity several times the average daily consumption of water it can clarify a muddy water to a degree that renders it of acceptable appearance generally, but not wholly free from sediment or from the products of coagu- lation. It is essentially a clarifying process which thus far does not offer immunity from danger of disease germs which may reach the raw river-water. The bacterial reduction which results is purely an incident of the removal of the turbidity and is not complete. The process of sedimentation as now practiced in its most developed form can be considered safe only when applied 156 WATER-SUPPLIES. to the clarification of a water which when fairly well clarified is altogether wholesome. There is a decided and natural temptation to economize in the use of a coagulant whenever there is any apparent excuse for doing so, consequently we find the coagulant used very unsys- tematically. Such a course is very likely to follow frequent changes of management of municipal water-works or to sug- gest itself to a superintendent of a private company for the pur- pose of increasing revenue. Very few of the small water- works under either private or municipal control seem to provide them- selves with adequate facilities for either an intelligent or a sys- tematic application of a coagulant even when experience con- cedes the necessity for its use. The attendants of these small plants and even of large water-works frequently get into a rut and follow the same routine day after day regardless of the necessity to modify the manipulation of the clarification works to meet the varying condition of the raw river-water. The fault of unsystematic work in this regard is not primarily that of the attendant as a rule, but rather that of the management, which may be either too inexperienced to exercise proper judgment or too far away to properly appreciate local conditions or to know actual requirements from day to day or month to month, and unwilling to delegate flexible administrative powers to the local superintendent. Winter Treatment. A popular impression prevails that river-water like that of the Missouri and similar rivers is most impure during an excessively muddy condition. Doubtless a river-water may contain the greatest number of bacteria at flood stage, but unsightliness and the presence of a large num- ber of bacteria should not be confounded with dangerous pollu- tion. It is not the sediment in the water or the actual number of bacteria which should be chiefly regarded in estimating the hygienic quality of a water, but rather the character of the bac- teria found to be present, particularly when of sewage origin. Most of our large rivers receive sewage from many towns and cities in volumes which vary between comparatively nar- row limits, while the volume of discharge of a river varies between wide limits. Consequently the low-water flow of the midwinter RIVER-WATER SUPPLY. i$7 season dilutes the sewage to a far less degree than the flood flow of the spring and summer seasons, and accordingly we may natu- rally expect to detect evidence of dangerous pollution more readily during the low-water stage of winter. At this season of the year the sluggish flow of the ice-coated detrital river reduces its sediment-carrying capacity to the lowest limit and the water becomes so clear that attendants unsuspicious of its hygienic condition have no hesitation in passing it into the water-mains almost directly from the river intake. The temptation then is particularly strong to dispense with the course of treatment which the water usually receives in a more turbid condition in order to save work and to reduce operating expenses. The self-purifying capacity of rivers and the high degree of dilution which sewage frequently receives in mixing with the water of some large rivers, even at low-water stage, may render the danger of infectious matter entering the water-supply inesti- mably low. But when the conditions for self-purification are unfavorable and sewage pollution is comparatively recent, the settling-basin affords an inadequate safeguard because little bacterial improvement of a polluted water can be expected from several days' storage in an ice-covered settling-basin. The treat- ment of the water with the ordinary coagulant at such a time can scarcely add to security by reason of the absence of germi- cidal properties of the ordinary coagulant and of the failure of the coagulant to collect and to settle quickly in the compara- tively clear and ice-cold river-water. But it is sure that even any slight advantage that may then follow the use of the coagu- lant will be dispensed with for economic reasons from the moment the river begins to clear and the visual necessity for its use is no longer apparent. It is clear, therefore, if sewage pollution can be detected in the comparatively clear water of an ice-bound river and there is available only the settling-basin in which to remove the danger- ous or infectious matter, that the prompting motive of using and manipulating the settling-basin must become one directed to the purification of the water to meet a standard of hygienic purity rather than one of clearness, and accordingly in some localities midwinter treatment must differ from summer treatment. 158 WA TER-SUP PLIES. Germicides. A consideration of the use of the settling-basin for the production of a wholesome water from one that is bac- terially impure presents a new and a possible range of develop- ment. The accomplishment of such a development of the settling-basin must have considerable influence upon the character and cost of purification works. It might result in the practical restriction of the biological filter, and possibly of the mechanical filter, to uses for clarification purposes and would extend the useful life of existing settling-basins indefi- nitely. Whenever a germicide is discovered which is harmless in its effect upon the water-supply, effective in the destruction of pathogenic germs, easy of application, and comparatively inexpensive, whether it be ozone or sulphate of copper or some other germicide, it is sure to receive an application in sterilizing water which may modify if not revolutionize our present methods of water-supply purification. Thus far the use of sulphate of copper, suggested by Dr. G. T. Moore as an algicide for use in destroying chiefly the algae which accumulate so rapidly in storage reservoirs, promises to become a germicide of extended use just as soon as scientists, physicians, and the public can be convinced that it has no deleterious effect upon a drinking-water. Of course the use of a germicide which destroys germ life through some other effect than by a toxic effect would more quickly become popular, but experiment has not progressed far enough yet to finally determine the feasibility of the use of a germicide of the former character; but we are even now confronted with the problem of determining both the actual safety and the safe range of application of a germicide of the latter class. In order to facilitate the use of the sulphate of copper as a germicide the manufacturers of the sulphate-of-iron coagulant design to combine the two salts in the process of manufacture so that the coagulant and germicide may be introduced simul- taneously in the same solution. For certain practical reasons the use of the combined salts may be advantageous, but from a technical point of view the combination in a single solution is of doubtful utility, for the reason that the conditions requiring a variation of the coagulant from time to time do not necessarily require a similar variation of the germicide, while in midwinter RIVER-WATER SUPPLY. 159 the use of the germicide alone may be needed to sterilize the water. However the manner of introducing a germicide into a water can be readily determined after the practicability and range of its use shall have been finally settled. At the present time it is too early to predict to what extent the use of a germi- cide may influence the use of the settling-basin, but there is now substantial warrant for stating that the settling-basin is sus- ceptible of still greater development and that it is destined to become a more highly regarded and scientific element in the art of water purification in which germicidal action may become an important part of the process. We cannot dispute the fact that the successful use of a coagu- lant and of a germicide with a view of purifying or sterilizing water forces upon us the necessity of providing skilled super- vision. The character of the raw water, its influence upon chem- icals introduced in the process of treatment, the preparation of the water to receive the chemicals when necessary, the specific action of the chemicals, their effect upon the water treated, and the best physical condition of the water to promote germicidal action, together with the practical difficulties which arise in treat- ing water in large quantities, are all matters which can scarcely be entrusted to the regular attendant of water-works, but which must be understood and their worth appreciated by the manage- ment through some guiding mind trained to investigate and capable of reducing analytical data into some simple rule of guidance. We cannot avoid the necessity of treating water for hygienic purposes so long as our customs and manners of life serve to pollute directly and indiscriminately the sources from which much of our drinking-water is derived. We must either maintain our rivers in a consistent state of purity or purify poi- luted water taken from the rivers to an extent conforming to a high standard of hygienic purity or seek unpolluted sources of supply. Natural Coagulation. The natural prejudice to the use of the ordinary coagulant in treating the water-supply and the jus- tifiable objections to its careless use leads to suggesting a sub- stitute which is occasionally available and is well worthy of a trial application. A few cities drawing their water-supply from 160 WATER-SUPPLIES. detrital rivers have also available a ground-water naturally impregnated with iron held in solution by carbonic acid. The well-known properties of an iron water to precipitate the iron as a hydrated oxide upon aeration and of hydrate of iron to act as a coagulant suggests the expediency of cities so located develop- ing ground-water and mixing it after aeration with that por- tion of the water-supply which is taken from the river. Theo- retically the hydrate of iron of the well-water should in part at least coagulate the remnant of the sediment in the river-water after exposure to a proper period of natural sedimentation. The use of the artificial coagulant would then be confined to an amount needed only to reinforce the natural hydrate-of-iron coagulant if for any reason it should be found to be deficient in quantity. Of course when the amount of ground-water available is sufficient for the entire supply of the city, all that is necessary is to remove the iron from the ground-water by methods described on preceding pages. But when the amount of this ground-water is insufficient for a full supply of water the deficiency drawn from the river and naturally settled may be so thoroughly coagu- lated by the iron in the ground-water as to be thoroughly puri- fied by the ordinary methods of sedimentation and filtration. Where the facilities for natural coagulation exist a trial can be so readily and inexpensively made that it is well worth the ex- penditure of time and money in view of the attractive induce- ments which the practical application of the process presents. There are localities available for the purpose where the iron of the natural ground-water has been found to vary from three- quarters of a grain to over four grains to the gallon, which is a range of iron for coagulating purposes suited to a wide range of turbidity of a naturally settled river-water. Attention should be given, of course, to the respective mineral character- istics of the water from the two sources of supply with a view of maintaining as low a degree of mineralization of the purified water as possible. But this is a matter to be worked out in de- tail when the application of natural coagulation is contemplated. The naturally coagulated water should be subjected to subse- quent sedimentation or filtration as in the case of waters treated with an artificial coagulant. RfrBR-WATER SUPPLY. 161 Filtration. The mechanical action of the process of sand filtration is a process of clogging whereby the voids of the sand gradually become filled and practically impervious near the surface of the sand-bed. In slow sand nitration the clogging process is essentially confined to a comparatively thin layer of sand at the surface and to a surface mantel of arrested impuri- ties. A few inches of head or water pressure is sufficient to cause water to freely flow through clean filtering-sand at the ordinary rate of nitration of 45 to 135 gallons per square foot per day. But as the clogging process progresses, the water- pressure required to force water through the obstructed passage in the sand at the stated rate gradually increases until it reaches the practical limit of 4 to 6 feet. Then the surface of the filter must be relieved of the coating of impurities together with to | of an inch of the surface sand where the clogging is the most intense. The rate of filtration of mechanical filters is much greater than that of slow sand-filters, usually approximating a range of 2000 to 3000 gallons per square foot per day. This high rate of filtration causes a much deeper clogging of the filter sand, and were it not for the coagulant, which is always necessary in mechanical filtration, fine sediment would stream through the pores of the sand and enter the filter effluent. The coagu- lant when allowed sufficient time to act collects the particles of sediment in masses and assists materially in the operation of clogging as the water flows through the sand at the stated high rate. The penetration of clogging matter into the sand- bed is necessarily much deeper than in that of the slow sand- filter, and the rate of clogging is directly proportional to the rate of filtration. Consequently in mechanical nitration the filtering-sand cannot be cleaned by scraping, but requires noth- ing less than a complete stirring up and attrition of the sand, grain against grain, to separate the clogging material from the sand and to dismember the coagulated masses sufficiently to pass off in a flow of wash-water passing upwards through the sand at a rate four or five times greater than the stated rate of ni- tration. All of the sand in mechanical niters is washed at every washing, but only the dirty sand from slow sand-filters is washed. 1 6 2 WA TER-SUP > PLIES. Consequently if the ratio of the superficial area of mechanical filters to slow sand-filters is i to 25 for a given quantity of water filtered per day, then for a depth of 30 inches of sand the me- chanical filter will require about twenty times more wash-water than the slow sand-filter for the same grade and amount of clogging material removed and with equally perfect mechanical facilities for performing the washing. There is a biological action in slow sand filtration in some conditions of raw river-water which serves by vital processes of living organisms to reduce organic matter and to extinguish bacterial life. This process is more particularly applicable to waters of comparatively low sediment contents which are pol- luted by organic matter, particularly sewage. The efficiency of a filter depends in a measure upon its clog- ging capacity, and accordingly upon its mechanical make-up and the skill bestowed in its operation and maintenance, and is measured by the degree of clearness and hygienic purity of the filter product. Thus filtration as now understood is a refining process which as a part of a clarification process removes suspended matter which natural or plain subsidence coupled with coagulation can- not remove, or which as a purifying process removes not only the suspended matter in water but also a very large propor- tion of the bacteria which a raw water may contain. In the one instance the essential consideration is to clarify an other- wise wholesome water, while in the other instance it is to elimi- nate the living organisms with a view of excluding from the fil- tered water any disease germs that may be in the raw water. With some waters the distinction between clarification and purification is a theoretical rather than a practical one from the fact that the refining process which insures complete clarifi- cation also accomplishes so great a reduction of bacteria that the product of the filter is considered safe and wholesome. This is true of the raw water of large detrital rivers containing a large amount of finely divided clay and possibly polluting matter in a highly diluted state. There is this distinction, however, to be made between clarify- ing filtration and purifying filtration, namely, that the one is RIVER-WATER SUPPLY. 163 governed largely by the appearance of the filtered water, while the other regards sanitary consideration to such a degree that the quality of the filtered water must conform to a hygienic standard of purity, which general experience, modified perhaps by local considerations, has found to be a safe guide in judging of the wholesomeness of a water. Purifying filters must be operated continuously, whereas the operation of clarifying filters is sometimes dispensed with when the water from the source of supply is clear, as is the case with detrital rivers when ice-bound. Notwithstanding the distinction of theory which may be made between clarifying and purifying filtration, this fact stands out clear and distinct, namely, that filtration in any form and for any purpose should be regarded as a refining process and should be so conducted that the effluent of the filter meets the require- ments of a standard of purity for a wholesome drinking-water,, except when applied merely to the preparation of water for some mechanical purpose, when a sanitary standard of purity may be disregarded. In order that filtration may meet sanitary requirements the mechanical operation of filters must be under perfect control a requirement which renders imperative a perfect control of the condition of the water admitted to the filter and of the rate of flow through the filter. Accordingly we must have a standard of hygienic purity for the filtered water and a standard, more flexible perhaps than the former, to so govern the condition of the water admitted to the filter that the filter can continually produce a water conforming with the hygienic standard. The most available guide as to what constitutes an acceptable standard of purity of a filter effluent is the one in use in the Ger- man empire as follows: "Section i. In judging the quality of a filtered surface-water attention is to be paid to the following points: (a) The opera- tion of the filter is to be regarded as satisfactory if the number of bacteria in the effluent does not exceed that limit which experi- ment has shown to be attained by good sand filtration at the water-works in question. ' A satisfactory effluent shall as a rule not contain more than about 100 bacteria per cubic centimeter 1 64 WATER-SUPPLIES. when it leaves the filter, (b) The filtrate must be clear as pos- sible, and must not be inferior in color, taste, temperature, and chemical character to the water before filtration. "Section 2. In order to control a water-works continuously in its bacteriological relations, it is advisable to examine the effluent of each filter daily where the conditions permit. Such a daily examination is particularly important: (a) after the con- struction of a new filter until it assumes its regular working con- ditions; (b) whenever a filter is put in operation after cleaning and for at least two days after that time, until the effluent has a satisfactory character; (c) after the filtration head becomes more than two-thirds of the maximum for the works in ques- tion; (d) when the filtration head suddenly decreases; (e) during all unusual conditions, especially at times of high water. "Section 3. In order to be able to conduct bacteriological investigations according to Section i (a) the effluent of each filter must be accesseble, that samples may be taken at any desired time. "Section 4. In order to assume a uniform system of bac- teriological investigations the method given below is recom- mended for general use. "Section 5. The persons intrusted with the conduct of the bacteriological investigations must furnish proof that they possess the qualifications necessary for the work. They should belong to the official operating staff itself whenever possible. "Section 6. If a filter furnishes water which does not meet the hygienic requirements, it is to be cut out of service, pro- vided the cause of the deficient character has not already been removed during the course of the bacteriological investigations. In case a filter furnishes an unsatisfactory effluent oftener than occasionally, it is to be placed out of service and the defects sought out and remedied. " Section 7. In order to be able to waste poor water which does not meet the requirements each filter must be arranged so that it can be cut off from the filtered water-mains and the effluent allowed to flow away. This waste is to take place regu- larly, so far as the details of management permit, (a) immedi- ately after the complete cleaning of the filter, and (b) after com- RIVER-WATER SUPPLY. 165 pletely renewing the bed .of sand. The superintendent in charge must determine, from his experience with the bacteriological investigations, whether a waste of effluent is necessary in each individual case after the completion of this cleaning or renewal and the length of time that must elapse before the effluent attains the required degree of purity. " Section 8. It is necessary for satisfactory sand nitration for the surface of the niters to have ample dimensions and provide sufficient reserve to assure the velocity of nitration suitable for the local conditions and the character of the raw water. "Section 9. Each filter-bed must be controllable as respects quantity of effluent, excess pressure, and character of effluent. It must also be arranged so that it can be completely emptied, and also be filled from below with filtered water after each clean- ing. "Section 10. The speed of filtration in each filter-bed must be capable of adaptation to the most favorable conditions for filtration at any time, and be as regular and free from sudden fluctuations or interruptions as possible. To this end the usual fluctuations caused by the varying demand for water during different portions of the day are to be equalized as far as pos- sible by reservoirs. "Section n. The filter-beds are to be so arranged that their operation will not be influenced by varying levels of the water surface in the clear-water reservoir. "Section 12. The excess filtration head must never be so great that breakage of the filtering-top layer can occur. The limit to which the excess pressure may rise without influencing the effluent is to be determined for each plant by bacteriological investigations. " Section 13. The filters shall be constructed in such a manner that every portion of the surface of each bed shall work as uni- formly as possible. " Section 14. The walls and bottom of a filter are to be water- tight, and particularly must there be no danger of an imme- diate connection or passage through which raw water may pass from the filter into the filtered-water main. For this purpose 1 66 WATER-SUPPLIES. special attention is to be paid to a water-tight construction and maintenance of the air-shafts of the filtered-water mains. "Section 15. The thickness of the bed of sand shall be at least so great that the cleaning will never reduce it to less than 30 centimeters (12 inches) where the conditions permit. Never- theless it is recommended that this minimum limit be raised to 40 centimeters (16 inches) where the conditions permit. "Section 16. It is desired that annual reports be made from all the sand-filtration works in the German empire to the Imperial Board of Health, giving the results of operation, and particularly the bacteriological character of the water before and after ni- tration." Experience or local requirements may suggest modifications of the quoted regulation. But in whatever degree modifica- tion may be found advisable, conformity thereto requires a methodical uniformity of the methods of operating filters and perfect control of the facilities for preparing the raw water for the filters. It is well known to those who have observed the operation of filters and who have studied the results of filtration that a uniform rate of flow through the filter and sufficiently long expo- sure of the water to the purifying agency is necessary to insure that degree of purification which will meet the requirements of a proper standard of purity. But a uniformity of flow through the filter cannot be preserved if too wide a range of the amount of sediment in the water supplied to the filter is allowed, for then the rate of clogging becomes variable, requiring a propor- tionately irregular fluctuation of the filtering water-pressure even beyond permissible limits, and resulting in an irregularly turbid-water delivery of the filter. Under these circumstances the bacterial efficiency of the filter is also reduced because high bacterial variation invariably accompanies a sudden or excessive variation of turbidity of the filtered water. In other words, the filtering-machine is then overworked, overclogged, and disor- ganized, and accordingly fails to respond to the requirements of the situation to deliver an acceptable product. The neglect to provide the facilities which insure a uniformity of the physical condition of the water entering a filter and of the * RIVER-WATER SUPPLY. 167 working regime of the filter itself accounts for numerous failures of mechanical filters and for the occasional disappointing result of slow sand-filters whenever the physical and bacterial con- dition of the raw river-water is made to vary through natural causes. Practice in this regard must be modified in this country and far more attention must be given to the preparation of the raw water for filtration if the results are to conform reasonably well to a standard of hygienic purity of the order quoted from the German. So long as the theory prevails that certain forms of bacterial life in water are to be feared rather than the dissolved impuri- ties, and so long as the science of biology, or rather the line of practice based upon the developments of this science, is unable to discriminate with precision between the harmless and danger- ous bacteria and to identify individual types independently, we are bound to consider the complete removal of bacteria from the water-supply, or if complete removal be found imprac- ticable, then to eliminate the probability and to minimize the possibility of the presence of the more dangerous forms of bac- teria. At the present time this principle or rule of practice appears fundamental, and if fundamental, then the practical standard of purity should be based upon a limited number of bacteria remaining in the filtered water rather than upon a percentage of the number in the raw water removed by filtration. But why not sterilize the water and be done with it and make this the universal standard of purity? To this puestion an answer is that it is useless to plunge into a labyrinth of practical difficul- ties which surely must involve one who attempts to obtain a sterile water from an artificial filter, for the filter has practical limitations depending upon its design and construction, upon the method of operation and upon the condition of the water ad- mitted to the filter. It is perfectly plain, to use an extreme case, if the water could be sterilized before entering the filter that the work of the filter would be confined to that of clarification, and that structural and operating details would then be of a character which would prevent the filter becoming a breeding- place for bacteria. While we can scarcely hope for such perfection 1 68 WATER-SUPPLIES. in the works intended for the preparation of water for niters as to produce the result just outlined, still the nearer that sort of prep- aration is approached the more readily can a high standard of purification be attained. It is the pivotal point to-day in the proc- ess of water purification. If energy is concentrated upon the per- fection of mechanical devices in and about filters, relying purely upon filtration as modified and influenced by the mechanical devices to produce results, the longer will the attainment of a high standard of purity of filtered water be postponed. On the other hand, if energy is devoted to the perfection of works for the preparation of water for the filters of a quality which renders high-grade filtration not only possible but positive, the sooner may we expect to see rapid advances made towards the adoption of a universal high-grade standard of hygienic purity of the water-supply. Accordingly there appears no good reason for much flexibility in the quoted standard of hygienic purity in order to meet varying natural conditions of the sources of water-supply as they change geographically, because the vari- able conditions call for a modification rather of the preliminary treatment of the water and accordingly a modification of the structures by means of which the preliminary work is accom- plished. Whatever elasticity there may be in methods and means of water purification should be largely confined to the prelim- inary preparation of water before it reaches the filter. And the extent to which the physical condition of the raw water must be improved before it is admitted to the filter is largely a matter for local consideration and must be settled independently in individual instances. The city of Bremen, Germany, takes its supply of water from the river Weser and meets the requirements of the German standard of purity of filtered water by resorting to double filtra- tion. Eugene Goetze, Esq., chief engineer of the water-works of that city, in a paper presented to the American Society of Civil Engineers September 4, 1903, concisely outlines the phys- ical condition of the river-water and the results of filtration in these words: "The number of bacteria in the raw water of the Weser, which normally is about 1000 to 2000 per cubic centi- meter but often is only a few hundred, increases at high water, RIVER-WATER SUPPLY. 169 such as occurs regularly once or twice in the fall and once or twice in the spring, to 100,000 per cubic centimeter. ... In Bremen the water formerly filtered by single filtration contained during every flood 1000 to 3000 bacteria, instead of the permis- sible 100 and was quite turbid besides. Since the introduction of double nitration the city receives also, during floods, a clean filtrate with no more than about 100 bacteria per cubic centi- meter." The raw water from the river Weser is admitted directly to the Bremen filters, and the requirements of the German standard of purity are met by single filtration under ordinary conditions of the river-water and by double filtration upon those occasions when the river-water is abnormally turbid, which may be inferred is for a comparatively brief period each year. The Bremen filters are the biological or slow sand type, which are cleaned by scraping. In this connection Mr. Goetze states: "The filtering periods between consecutive cleanings range from a minimum at a time of high water of about 7 days to a maximum of about 120 days, the average being 30 to 35 days." It is gathered further from Mr. Goetze's tabulations of results that the abnormal turbidity of the raw Weser water scarcely reaches 200 parts per million, and that single filtration suffices for a turbidity of the raw water of about 20 to 30 parts per mil- lion or less. In the matter of slight turbidity, or rather of a narrow range of turbidity, the few rivers of the United States which are com- parable with the Weser are principally those of the New England and neighboring States. Many rivers of the Middle West and of the South are muddy, carrying a sediment in excessive amounts during the greater portion of each year. While double filtration may answer the requirements of a proper standard of purity with waters similar to that of the Hudson and Merrimac rivers, it could not be used to satisfactorily purify or clarify the waters from most of the rivers of the Middle West. The burden of sedi- ment is far too great. The following table taken from the report of the Water-supply Commission of St. Louis, 1902, shows approximately the average amount of sediment in river-water at several localities. 1 70 WA TER-SUPPL1ES. Parts per million. Merrimac River, Lawrence 10 Hudson River, Albany 15 Allegheny River, Pittsburg 50 Potomac River, Washington 80 Ohio River, Cincinnati , 230 Ohio River, Louisville 350 Mississippi River, New Orleans 650 Mississippi River, water-works intake, St. Louis . . 1200 Mississippi River, Missouri side, St. Louis 1500 Elsewhere in this chapter is shown the large amount of sedi- ment carried by the Missouri River near Kansas City, ranging from 500 to over 6000 parts per million, averaging nearly 3000 parts per million during the months of open river. When the river is ice-bound the river-water is turbid only, the turbidity ranging from 30 to 50 parts per million, or possibly less during protracted freezing weather. It is obvious that rivers like the Missouri, Mississippi, and Ohio, having a wide range of sediment capacity marked by sudden variations, cannot receive satisfactory preparation for filtration in preliminary niters, for the burden of sediment is so great that it can be disposed of successfully by the less expensive method of sedimentation. The settling-basin is usually the place where the roughening work of preparation can be accomplished and where the water can be prepared thoroughly for the refining work of the filter to a degree that will meet the requirements of a standard of hygienic purity of the filter effluent. But there must necessarily be some fixed limit to the turbidity of the effluent from the settling-basins, in order that the filters may satisfactorily perform the after-work. What should be this limit of turbidity ? George W. Fuller, in his report of the Cincinnati experiments relating to the "English" (slow sand) system of filtering, states: " Upon taking into consideration all of the evidence at the close of the work, it is finally concluded that the maximum permissible amount of clay in the Ohio River water applied day after day to English filters under local conditions ranges from about 30 to 70 RIVER-WATER SUPPLY. i? 1 and averages between 40 to 50 parts per million." " To make use successfully at all times of English filters it would be necessary at times of freshets to give the Ohio River at Cincinnati further preparatory treatment than is afforded by three days of plain subsidence." Robert Spurr Weston, in his report on the New Orleans experi- ments, states with regard to English niters that, " barring compli- cations from algae growths which would tend to reduce the yield of the filter between scrapings, a silica turbidity of 35 parts per million (about 20 parts of suspended matter) would, on an average, permit according to available data regarding local conditions^ a yield of about 65 million gallons of filtered water per acre, or a period of service between scrapings of about 13 days, when a head of four feet is used. ... If the water applied to the filter should be as low in turbidity as 20 parts per million, silica standard, the yield of filtered water between cleanings would be considerably more, and the penetration of the clay into the sand layer would very likely be a little less. On an average, and in the ab- sence of algae growths, the data indicate that with such an applied water a yield of 100 million gallons per acre between scrapings, equivalent to a period of service of 20 days, could be obtained, and that the depth of sand removed by scrapings would be less than one inch. It seems doubtful whether, as a rule, it would be economical under local conditions to apply sufficient coagulant to reduce the silica turbidity of the filter influent to 20 parts per million (about 12 parts of suspended matter), although better re- sults would probably accompany the lower turbidity." Mr. Weston, in summing up the results of experiments with mechanical filters at New Orleans in purifying the Mississippi River water, gives the table reprinted on page 172. With reference to this table Mr. Weston says: " It is believed from the above that it is not economical to apply a coagulant to reduce the turbidity of the water to below 50 parts per million (30 parts of suspended matter per million). It is also believed that considerable saving is affected by reducing the turbidity to below 75 parts per million (45 parts of suspended matter per million); but it is an open question what should be the proper turbidity between these general limits to which to reduce the I 7 2 WATER-SUPPLIES. subsided water in order to effect the most satisfactory and eco- nomical filtration." TABLE X. APPROXIMATE RELATION BETWEEN TURBIDITY OF FILTER INFLUENT, PERCENTAGE AND COST OF WASH-WATER, AND YIELD op THE FILTER BETWEEN THE WASHINGS. Influent. Wash-water. Silica, turbidity. Parts per million. Suspended matter. Parts per million. Percentage. Cost per million gallons. Period of service. Hours. Yield, million gallons per acre per day 2 5 15 1-5 $0.27 29 ISO 50 3 2 .O 0.36 21 no 75 45 3-o o-54 13 70 IOO 60 4.0 0.72 10 50 150 90 6.5 i-i? 6 30 Other statements of the general tenor may be given, but all point to what must be recognized as a fact that within proper limits the lower the turbidity of the water admitted to a filter the higher and easier becomes the permissible degree of purifi- cation of the water in passing through the filter. Particular attention is called to the amount of wash-water that is required. It is seen in the preceding table that 6J per cent of the total product of the filter is required for washing purposes when the raw water contains 90 parts per million of suspended matter; it is also known from general practice that the percentage of wash-water increases rapidly as the amount of suspended matter in the raw water increases, and soon reaches a point where the large percentage of wash-water coupled with an excessive use of a coagulant renders the expense prohibitive. With high sediment contents of the raw water, moreover, filters cannot be maintained in an efficient working condition. The practical limitations to the reduction of turbidity may approximate 50 parts per million for water of silt -bearing rivers, during the unfavorable seasons of the year, by the skillful use of a coagulant after the water has experienced a period of natural subsidence of 12 to 24 hours. A greater reduction of turbidity may be readily effected during more favorable seasons of the year with the use of a less amount of coagulant skillfully applied to RIVER-WATER SUPPLY. 173 an amount approximating 20 parts per million, also after a similar period of plain subsidence. But in any event the reduction of turbidity to a proper degree to admit of successful filtration of the water of silt-bearing rivers must be obtained with the aid of a coagulant used approximately in the amounts indicated else- where in this chapter. Two serious difficulties arise in connection with the operation of a settling-basin in a skillful manner, one is the objection to the expense entailed in the use of a coagulant in the skillful manner and in the amounts required for the reduction of turbidity to the extent indicated above and the other is the popular objection to the use of a coagulant in large amounts. Either objection can be met only by insisting on the one hand upon a proper standard of purity of the filtered water and on the other hand by a more general familiarity with the process of coagulation and the necessity for the use of the coagulant. The capacity of the basin that is required for coagulation and subsidence after coagulation and for temporary unserviceability during the cleaning or washing process amounts to 24 to 36 hours, which capacity added to the 12 to 24 hours' capacity required for plain subsidence makes the total capacity of a basin required for successful operation of 36 to 60 hours' supply, without considering the capacity of the needed clear-water storage-reservoir. The velocity of flow in some rivers is so low for a considerable portion of each year that the river-prism becomes a subsiding-basin. Then the raw river-water may be given a treatment with the coagulant as taken from the river and afterwards allowed a few hours' rest in a basin before going to the filters to allow the coagulant time to collect in masses large enough to be retained by the filter-sand. The current of other rivers is so rapid the year through, except when ice-bound, as to require basins of the capacity stated in the preceding part of this paragraph. Accordingly there is room for a considerable latitude of judgment in fixing upon the capacity of subsiding-basins which will meet the general requirements of local conditions most economically. The amount of clear-water storage at the purification works need not exceed that which will safely obviate the necessity of forcing the settling-basin beyond its proper turbidity-reducing capacity. 174 WATER-SUPPLIES. Fig. 23 shows a plan of a water-purification works (not con- structed) designed to purify water taken from the Missouri River at Fort Leaven worth, and serves to illustrate a purification works combining natural subsidence, coagulation, and mechanical filtration, and also a convenient arrangement of valves for manip- ulating the basin. to River FIG. 23. Plan of Settling-basin, Mechanical Filter, and Covered Clear- water Basin. The purification plant is designed for the delivery of at least one million gallons per day of wholesome water. The settling-basin is in three divisions, one division of a capa- city of 1,227,600 gallons, the second of 852,000 gallons, and the third of 438,000 gallons capacity. The mechanical filters are each 17 feet long and 10 feet wide and of an estimated normal filtering capacity of about 400,000 gallons each per 24 hours at RIVER-WATER SUPPLY. 175 a rate of about 100 million gallons per day per acre, or a little over 1.6 gallons per square foot per minute. Sectional elevations of the purification works are shown in "0 r IT: Fig. 24, and a general plan of the pipe system, valves, and gate- chamber on Fig. 25. The 12-inch raw-water influent-pipe divides at the gate-chamber i 7 6 WATER-SUPPLIES. wall into two branches, one leading into division i, and the other into division 2 of the basin. At the end of each branch of the influent-pipe is a deflector which gives a horizontal radial direction to the water in a direction away from the valve-chamber. RIVER-WATER SUPPLY. 177 Under normal working conditions the raw water entering the bottom of division i through the 1 2-inch influent-pipe just de- scribed, displaces an equal volume of the surface-water which passes into the adjoining quarter division of the gate-chamber through a notch in the octagonal wall admitting of a stream about 6 inches deep and 12 feet long. In passing through this i 7 8 WATER-SUPPLIES. notch the coagulant solution is introduced through a series of J-inch pet-cocks tapped into a 2-inch coagulant-pipe. From the quarter division of the gate-chamber the water passes into a branch pipe in the division-wall of the gate-chamber and enters ^C" Vent Pipe ,1.000.5 (p (P > fp W- P- . \m SECTION B-B ^- El. 614 j}:= = j:j=|t^=^ S- ---jr ------^--=---- -----A------^ the influent-pipe of division 2 of the settling-basin, which con- veys it into basin 2, where it is deflected horizontally and radially as described above for division i. The return-flow of the displaced water of division 2 enters a second quarter of the RIVER-WATER SUPPLY. 179 gate-chamber by overflowing a second section of the octagonal wall, or that between the two division-walls of the basin; whence it enters through a sluice-gate the influent-pipe of division 3, which pipe distributes the water in division 3 in a manner similar to that described for divisions I and 2. The water from division 2 can be given a second treatment of i8o WATER-SUPPLIES. the coagulant solution in passing into the gate-chamber in the manner described for the first treatment. When division 2 is empty for cleaning the effluent from division i passes from the irregular quarter of the gate-chamber into the square quarter of the same chamber through a sluice-gate, thence by pipe connection into the influent-pipe of division 3. The valve manipulation for the other two basin combinations can be readily seen from the plans. The drain-pipe from each of the three divisions of the settling- basin, as well as the drain-pipe from each of the four divisions of the gate-chamber, enters a circular drain-well concentric with the gate-chamber (illustrated on the section elevation of the gate- chamber, Fig. 26) ; thence the drainage is conveyed by a i6-inch cast-iron pipe to the Missouri River. The pipe and valve system of the filters is shown in Fig. 25. Each filter has an independent influent-pipe from division 3, also a common 1 2-inch influent-pipe connecting with a division of the gate-chamber for use when division 3 is being cleaned. The plan affords such a centralization of the pipe and valve system of the entire purification works that a single attendant can readily attend to all valve manipulation under practically the same roof. The filter-walls are of reinforced-concrete construction, as shown by the illustrations. A distributing reservoir of 1,453,000 gallons capacity was designed to be constructed on an elevation above the barracks about one mile or more from the purification plant. A plan and section of this reservoir are shown in Fig. 27. Both the reser- voir and the clear-water basin connecting with the filters are de- signed to be roofed with reinforced concrete resting on similarly constructed girders and pillars and covered with about two feet of earth, the roof construction being identical in both instances. The detailed drawings in Fig. 28 suffice to show the proposed manner of erecting the molds and of constructing the roof. It will be observed that the roof is designed in wholly independent panels 14 feet square, with four panels cornering on each pillar. In passing it may not be amiss to state that the business enter- prise of the men who have been interested in mechanical-filter RIVER-WATER SUPPLY, 181 patents has contributed very greatly to the advancement of mechan- ical nitration to its present position in the art of water purification. It served to bring mechanical filtration before the public and to hold the attention of the public for years even before the merits of the mechanical filter had been thoroughly developed. Not- withstanding the efforts of mechanical-filter partisans to exploit the mechanical filter and to give it wide publicity, they often obscured the true merits of the filter in a decidedly foggy atmos- phere because of their neglect to accord consideration of the technical features which successful nitration naturally embraces, and it was not until the technical features of mechanical nitration and of the mechanical devices which are necessary to insure suc- cessful operation of a mechanical filter had been thoroughly studied that it was brought to its present standard of excellence. It has been clearly shown by extended experiments and by close analytical study that mechanical filtration, like slow sand filtration, requires a thorough advance preparation of the raw water before it is in a proper condition to enter the filter. The one is intended to be as much a refining process as is the other; as good results may be expected from one as from the other; and the perform- ance of the one method of filtration over the other is often a matter of adaptability and of cost. It may be safely said from a purely technical standpoint that with a sufficient advance preparation of the raw river-water either method of filtration can be used in any locality, even where such waters as that derived from the Missouri, Mississippi, or Ohio River are to be purified. It is found, however, that slow sand filtration together with the necessary subsiding basins for the proper preparation of the water for these filters involves so great an expense as to be practically prohibitive; and it is further believed that slow sand niters, when used in connection with purification works which require so thorough an advanced treat- ment of the raw water as that of the river just named, become in themselves purely mechanical filters, for the reason that the long period of subsidence and the large amount of coagulation to which waters from such rivers must be subjected doubtless remove from the raw water the elements or properties which are needed to con- 1 82 WATER-SUPPLIES. struct the filtering mantle which is supposed to be the effective element in the operation of the slow sand biological filter. In drawing this chapter to a close it may be briefly stated as a summary of what has been said that natural subsidence, coagula- tion, and nitration are necessary for the proper purification of the water from detrital rivers generally, and that there must be not only a high standard of purity for the effluent of a filter, but also a restricted range of turbidity to the filter-influent water. Without proper regard to the principles embraced in the three distinct processes and to the bacterial and physical condition of the water admitted to a filter it is found impossible to secure a water of uniform purity, or one that should be recognized as conforming to a proper standard for a good and wholesome water. The general practice of the present day is not up to the standard indicated. Principles are often disregarded, especially the one of preliminary preparation of the water for filtration, car- ried even to the extent of sometimes adding a coagulant to a water of very low turbidity in order to make filtration success- ful even through slow sand filters. If the author has succeeded in making this point clear and in helping on the work of reform in the directions indicated, it is believed that the chief obstacle to successful water purification by filtration can be overcome. CHAPTER in. PUMPING-ENGINES. THE pumping-engine is so important a part of the equipment of many water-works as to warrant a few words regarding its use and maintenance. Little can be said regarding the manufacture of machinery of this kind, as it is a special work carried out by corporations fully equipped to design and manufacture. The manufacturers, however, desire a thorough knowledge of the ser- vice in which a pumping-engine is required to work in practice, of the source of the water-supply, and of any physical conditions which may affect the installation of the machine and the service expected of it. Accordingly the engineer's specifications under which pro- posals of design, installation, and manufacture are invited and the purchase is made are usually confined to general stipula- tions defining and fixing the obligations of the contracting parties, a detailed statement of the conditions affecting both the installation and operation of the pumping-machinery as above outlined, and the terms of payment, etc. Frequently a certain type of machine is specified which is known to possess superior merits for a particular kind or range of service. Usually plans are submitted with the specifications to illustrate the description given therein and to show the design and arrangement of the pumping-station, together with the arrangement of plant and machinery already installed or about to be installed. It is usually customary for the purchaser to build the founda- tions upon which the machinery is to rest after plans of the manu- facturer showing the anchor-bolt lay-out and the design of the super- 183 1 84 WA TER SUPPLIES. structure to accommodate the type of machine proposed for instal- lation. Such a division of the work serves to facilitate matters and to reduce expense. The manufacturer, while providing the valves, fittings, and ac- cessories necessary to properly govern and operate the machinery, is seldom expected to carry his work outside the walls of the building in which the machinery is installed. Usually the purchaser requires of the manufacturer some sort of guarantee as to the degree of economy with which a proposed pumping-engine will perform the work of pumping water. Evi- dently the larger the number of gallons of water delivered by the pumps of a pumping-engine with the consumption of some given amount of fuel under the boilers or of steam by the engine, as the case may be, the less becomes the fuel expense and, relatively, the higher the economy of the machine becomes in operation. The measurable work of the pumps never accounts for all of the energy developed by the combustion of coal in the boiler-furnaces in the manufacture of steam, nor even for all of the energy in the steam admitted to the steam-cylinders of the engine actuating the pumps, for a large portion of the heat of the coal is unavoidably wasted, and also a portion of the heat energy actually absorbed by the steam is unavoidably lost in passing through the pipes leading to the engine, in the steam-cylinders themselves, and in overcoming the friction of the moving parts of the machinery which it actuates. Accordingly in practice the term "mechanical efficiency " is applied to pumping-engines, meaning thereby the relation which the work actually done by the steam in the cylinders bears to the work actually accomplished by the pumps in lifting water. Thus if the work done by the pumps divided by the indicated work in the steam-cylinder equals unity, as would be the case were the actual and the indicated work the same, then the engine is perfect mechanically and the mechanical efficiency is 100 per cent. But as this percentage measure of mechanical efficiency decreases the work of the engine decreases on the scale of economy; for instance, a machine giving a mechanical efficiency of 90 per cent is better designed and constructed than one giving 70 per cent. But the ordinary term for a measurement of economy of a pumping-engine is " duty " in terms of foot-pounds meaning the PUMPING-ENGINES. 185 number of pounds of water a pumping-engine is capable of lifting one foot high with the expenditure of a unit volume of fuel or steam. Formerly the unit volume was 100 pounds of coal or combustible. This basis of measurement is unsatisfactory to both the manufacturer and the purchaser of a pumping-engine because it necessarily embraces the evaporative capacity of the boilers and the mechanical perfection of the boiler-setting and steam-piping connecting the boilers with the pumping-engine. In other words, the pumping-engine ceases to be a unit of consideration in itself in a duty test. And from the very nature of the combi- nation of engine, piping, boilers, and furnaces, it is sometimes difficult and embarrassing to fix responsibility for failure of an engine to give a stated duty when the several units of the com- bination are the workmanship of as many different contractors, Moreover the technical details to be observed and the measure- ments to be taken in a combined test are many and often con- siderably complicated. Of late years it has been customary to use the unit volume as one thousand pounds of steam delivered to the engine at some stated pressure. The choice of this unit of volume simplifies mat- ters, and by isolating the boiler or boilers furnishing steam for the engine under test, or by measuring the amount of steam diverted from the engine under test for use in other directions, the obser- vations and measurements relating to a test are rendered less complicated than in the former case just described. This method of measuring the duty of a pumping-engine, while satisfactory from a purchaser's or a manufacturer's point of view, does not meet the requirements altogether for ordinary station practice, for the reason that it fails to show a direct relation between the work done in pumping water and in operating other station appurtenances and the coal consumed under the boilers. Consequently for sta- tion purposes it is often convenient to refer to economy in vari- ous terms, as steam consumption per horse-power per hour, coal consumed per horse-power per hour and coal consumed per 1000 gallons of water raised a given height, etc. In order to facilitate computations and to compare approxi- mately the various units of measurements the following formulae and tables are offered: 186 WATER-SUPPLIES. Let D = duty of pumping-engine in foot-pounds per 1000 pounds of steam consumed by engine; #=head or total lift of pump, including suction-lift; F= volume of water pumped per unit of time; say, for convenience, one hour; W weight of unit of volume of water, 8.34 pounds per U. S. gallon; S= weight of steam consumed per hour; H.P.=pump horse-power. One H.P.= 33,000 ft.-lbs. of work per minute or 1,980,000 ft.-lbs. per hour; C=coal consumed per H.P. per hour. HxVXWXiooo Thus > = - H.P. 5 HXVXW 1980000 D 1000X1980000 S 1000X1980000 HJ>=- D S 1980 or H.P. duty in million ft.-lbs. = steam consumption per horse-power per hour. From the last equation the following table is computed: STEAM CONSUMPTION PER PUMP H.P. PER HOUR FOR STATED DUTIES IN MILLION FOOT-POUNDS. 10 15 20 25 3 35 40 5 60 198 132 99 79.2 66 56.6 49-5 39-6 33 70 80 9 100 no 120 130 140 150 28.3 24.7 22.0 19.8 18.0 I6. 5 15.2 14.1 13-5 COAL CONSUMPTION PER PUMP H.P. PER HOUR, AT AN EVAPORATION OF 10 POUNDS OP WATER PER POUND OF COAL, OR WHEN C = S/io H.P., FOR STATED DUTIES IN MILLION FOOT-POUNDS. 10 19.8 15 13.2 20 9.9 25 7.92 3 6.6 35 5.66 40 4-95 5 3-9 6 60 3-3 70 2.83 80 2.47 9 2 . 2 IOO 1.98 no 1.8 120 I 3 1.52 140 1.41 x'.W PUMPING-ENGINES. 187 To illustrate the use of the table, suppose that a pumping engine was found to consume 22 pounds of steam per pump horse- power per hour, as measured by the weight of water evaporated by the boiler, and also that the boiler was found to evaporate 6 pounds of water per pound of coal. The duty, then, by the table would be 90 million foot-pounds per 1000 pounds of steam or per 100 pounds of coal on the basis of an evaporation of 10 pounds of water per pound of coal, or 54 million foot-pounds per 100 pounds of coal consumed under the boiler, and the coal consumed per pump horse-power per hour would be about 3.6 pounds. In every pumping-station a record should be kept of the amount of coal consumed in the boiler-furnaces and the number of revolutions made by each unit of the pumping-machinery and of the head or pressure against which the pumps operate, for infor- mation of this kind systematically and methodically recorded enables an engineer to keep posted upon the station duty of the several machines under his charge. The station duty is found to vary considerably from the test duty usually embodied in specifications governing the purchase of a pumping-engine, for the station duty is usually based upon a unit volume of the coal consumed and often takes into account boiler economy, waste, and the fuel consumed for all auxiliary engines as well as for the pumping-engines actually delivering the water into the distributing pipes. For instance, in a pumping- station recently inspected it was found that one pumping-engine which on test delivered 338 gallons of water per pound of fuel actually delivered in daily service 263 gallons of water for every pound of fuel consumed, that a combination of large and small pumping-engines delivered 156 to 172 gallons of water per pound of coal, and that the average annual station duty for a period of three years was from 150 to 167 gallons of water per pound of coal consumed. It was also observed when a proper correction was made for the slips of the pumps that the station duty became reduced for one year to 124 gallons of water per pound of fuel consumed. The working head against the pumps was about 323 feet. Thus it is observed that a test duty may be much in excess of the ordinary station duty and that when attendants become i88 IV A TER-SUPPLIES. careless or helpless regarding the mechanical condition of the pumping-engine the station duty based upon coal consumed and water actually delivered into the mains may run very low. Attendants may find it convenient to have a table or diagram showing the station duty of the pumping-machinery per pound of fuel consumed when the head or pressure against which the pumps operated is known. A diagram of this kind may be found on page 189. On other occasions when the annual amount of fuel to be charged against some specific unit volume of water, as 1000 gal- lons, is desired the diagram on page 189 maybe found convenient. Again, the annual cost of fuel per one million gallons of water raised some stated height, when the station duty is known, is another convenient unit often referred to; accordingly two diagrams on page 190 may be of service. The diagrams are based upon 300 feet head or 130 pounds gauge pressure, but a reduction to any particular working head in feet may be made by multiplying the annual fuel cost as ascertained from the diagram by the ratio Particular head in feet 300 A method of keeping the pumping-station records is given below. It may be varied somewhat to suit local requirements. DAILY STATION RECORD OF PUMPING-ENGINES. Date . . Description. Nominal capacity. Hours of service. Counter reading. Gallons of water pumped. Water pressure. Steam pressure. Vacuum. Starting Stop- ping. PUMPING-ENGINES. 189 300 400 500 600 700 800 900 1000 1100 .1200 1300 1400 1500 1600 1700 1800 1900 2000 Gallons of Water Raised per Pound of Coal Consumed FlG. 29. 12 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Amount of GoaTm Hundred Weight FIG. 30. Amount of Coal Required Annually to Raise 1000 Gallons of Water Daily 190 WATER-SUPPLIES. '$1000 6 7 8 9 10 11 12 13 \i J5 16 17 18 19 20 Annual Cost of Fuel in .Thousand Dollars FIG. 31. Annual Cost of Fuel Required to Raise 1,000,000 Gallons of Water Daily 300 Feet High, allowing 5% for Slip. .$1000 3 3 4 > 5 6 7 Annual Cost of Fuel in Thousand Dollars FIG. 32. Annual Cost of Fuel Required to Raise 1,000,000 Gallons of Water Daily 300 Feet High, allowing 5% for Slip. PUMPING-ENG1NES. 191 DAILY STATION RECORD OF BOILERS. Date. Description. Hours in service. Steam pressure. Temperature. Fuel. Remarks. Feed- water. Flue- gases. Coal. Ashes. A table has been prepared based upon data collected from the annual reports of water departments for the purpose of illustrating the station duties that may be expected from various types of pumping-engines. TACLE XI. s Pounds 8 No. of pump- ing days. consumed in raising steam in per cent of total coal con- Average head against pump. Gallons of water pumped per pound of coal. of coal required to raise 1000 gal- lons of water to Annual engine duty per loo pounds of coal con- sumed. Remarks. 1 sumed. stated height. i IOO 190 5-3 15786000^ Ordinary duplex comp. condens- 10 IOO 0.51 176.5 152 6.64 22370000 J ing i 6.08 173.2 288 3-48 High-grade comp. cond. duplex ii IO 302.4 126.6 6-33 2.82 242 181 259-3 335-7 3-86 2.982 52273000 50725500 Holly quad. Cornish beam I 152.8 406.8 2.458 51843600 Rotative duplex comp. condens- I 365 61.69 638.2 1.56 32807533 do. I 52.5 1162 . 5 0.86 50870200 Vert, marine type 7 360.6 o. 26 184.89 792.52 1.264 122076700 H igh - grade vert. It will be observed from the preceding table that the head against which a pumping-engine works is an important factor in comparing economy of operation and that if one is to draw fair comparison the work of the engines should be based upon a com- mon head of say 100 feet. Making this reduction we find the pounds 1 92 WATER-SUPPLIES. of coal required to raise 1000 gallons of water 100 feet high for the several types of engines referred to are respectively as follows: 5-3, 3-7 6 > 2 - OI > T -59> 1-65, 1-61, 2.53, 1.64, 0.68. The above table and succeeding computations should not be accepted as truly comparable, for unless all the conditions of service are known in each instance and an allowance made accordingly unfair comparison may result. All that is desired by the illustra- tion is an approximate comparison of the several types of engine. For instance the same type of engine working in direct-pressure service would not give as high a duty as when working under the conditions of reservoir service for the reason that in the former instance the speed of the engine fluctuates with the momentary and hourly requirements of service, while in the latter case the engine may operate under full load at its most economical speed hour after hour and day after day, regardless of the rate of water consumption. It is not easy to obtain pumping-station duties of the small water-works which use the non-condensing duplex type of pumping- engines for the reason that in the majority of cases the records are incomplete. The slip of pumps embraces the water which in the operation of a pumping-engine escapes through leaky or defective valves or churns backward and forth through a defective plunger packing ; that is to say, it is that portion of the pump-plunger displacement which does not reach the distributing system although raised to a pressure corresponding to that of the portion which does enter the distributing main. It requires proportionately as much fuel to support the slip of a pump as it does the delivery of the pump. For instance, to take an exaggerated case, if the slip of the pump is 50 per cent, then one-half the fuel consumed in running the pump- ing-engine would be used in supporting slip and one-half in deliver- ing water into the force main, or the annual cost of fuel would be nearly double what it should be were the pumps maintained in an efficient condition. It is surprising to see the inefficient con- dition which pumping-machinery is sometimes allowed to reach. To illustrate this condition reference is made to a controversy which arose a few years ago between a municipal corporation owning its own water-works and a private corporation dependent PUMPING-ENG1NES. 193 upon the former corporation for its supply of water delivered to the company's distributing-pumps at a very low pressure. The controversy of three years' standing related to the actual delivery of a pumping-engine of 9 or 10 million gallons capacity per 24 hours for the stated period of years and involved a considerable sum of money. A commission was finally appointed to arrive at the facts and to settle the controversy. Three independent methods of measurement were finally adopted by the commission: 1. The plunger-displacement method, with the pump operating against a tightly closed gate-valve on the force main. This method of slip measurement was acceptable to the owners of the machine and the purchaser of the water, but discarded by the party selling the water. 2. The piezometer method, by means of which a series of hy- draulic grade lines were determined on the very low-pressure flow-line furnishing water to both parties, into which a meas- urable and known quantity of water was delivered. The hydraulic gradients were established both above and below the point from which the volume of water in dispute was abstracted. 3. A weir measurement of the actual amount of water delivered by the pumping-engine in question when operated at different speeds under the pressure conditions corresponding to regular service. The difference between the nominal delivery of the pumps based upon plunger displacement and the actual delivery as measured by the weir gave the slip. The slip of the pumps as measured by these totally different and independent methods is as follows: 1. Displacement method 2872.34 gallons per minute 2. Piezometer method 3090.00 3. Weir method 2926.46 Average of the three methods . . 2962 . 9 gallons per minute The average computation of the slip was accepted as correct, and the test proved the substantial accuracy of the displacement method of slip measurement, and enabled the commission to employ various similar measurements of slip, previously taken, in 194 IV A TER-SUPPLIES. the construction of a diagram used in the correction of the records of the three preceding years and to arrive at the actual delivery, which was found to aggregate nearly 1960 million gallons of water and the slip to aggregate nearly as much. The condition of the pumps at the time of the test is repre- sented by the following table based upon weir measurement. Test number. Revolutions per minute. Nominal delivery in gallons per minute. Percentage which actual delivery was of nominal delivery. I 8.8 2702.79 0.0 2 10. 3102.47 4-5 3 10.6 3338.09 II . 2 4 II . 2 357-i2 15-5 5 12 .O 3786.97 21.8 6 12.8 4059.3S 27.0 7 14.13 4412.05 32-8 8 14-5 4543-70 38.8 9 15-4 4702.51 36.9 10 16.8 5309.22 44-2 ii 18.2 5751-66 48.5 It is obvious from the table that the fuel required to raise the 2702.79 gallons per minute of water to the pressure of distri- bution was absolutely wasted. This glaring example of waste through slip serves to illustrate forcibly the importance of timely repairs of the moving parts of the pumps. Moreover the comparative tests show that the displacement method of measuring slip by operating against a closed valve on the force-main under the pressure conditions of service is suffi- ciently accurate for practical purposes. It has the further value of being applied in any pumping-station with little or no expense. The valves in the force and suction chambers of the pumps become the source of serious slip whenever the valve-seats are allowed to become scored or the rubber disks unusually worn, and either one of these two causes will lead to the presence of the other. Usually the diameter of the pump- valves is about 3^ inches, and unless the rubber disks are capped with a metal plate of somewhat smaller diameter they open over the radial arm of the valve-seats under heavy pressure and allow the escape of water at each stroke of the pump. Prolonged leakage of this character under high pressure eventually scores the valve-seats and cuts the valve- PUMPJNG-ENGINES. 195 disks irregularly so much so that the hissing sound of water escaping through the valves is often distinctly audible. The lift of the valves should never be much, for the wear and tear of pump-valves depends not only upon the number of re- versals of the pump-plunger, but also upon impact at the instant the direction of the stroke of the plunger reverses. The impact becomes most serious when the pumps are forced beyond their rated capacity. Little need be said about the size and lift of pump- valves, as the purchaser can scarcely define details of this character precisely without assuming responsibility, in a measure at least, for the design of the machine and proportionately for the results of opera- tion. These details are usually left to the judgment of the manu- facturer under reasonable guarantees of maintenance and renewals of broken or defective parts for some specific period of time. Gen- erally speaking this course of procedure duly protects the inter- ests of both the purchaser and the manufacturer if the purchaser's specifications define with proper precision the actual conditions of service. If these conditions are not so defined, it is scarcely con- ceivable that the interests of the purchaser would be better or more safely served by interfering with the details of design except through the instrumentality of a master of the art of design. Loss by slip through the plunger packing is much more liable to be neglected in pumps internally packed than in those externally packed, for the reason simply that any lack of vigilance on the part of an attendant is less apparent in the former than in the latter case and correspondingly less liable to correction by an overseer, and for the additional reason that many inside-packed pumps are metal-packed and cannot be repaired except by lathe- work, for which class of work most small water-works are not prepared. Accordingly wear is frequently allowed to progress to an extent which under more favorable circumstances for repairs and better facilities for packing would not be tolerated. It might be observed that inside metal-packed pumps are only adapted to the pumping of water entirely free from dirt, and even when used in pumping clear water under moderate pressure it is profitable to make a timely purchase of duplicate plunger and rings to replace the old ones as they become worn sufficiently to 196 WATER-SUPPLIES. admit of pronounced slip. The old ones can always be repaired in some near-by city if no facilities are available at home for the purpose. The lowest-grade pumping-engine on the score of economy that is permissible to install in a water-works for daily service is the compound, non-condensing, duplex pumping-engine. The low economy of this class of machinery is offset in a great measure by its low cost and simplicity of design and operation, which makes it popular with small communities for the first five to ten years of experience with water-works. In fact it is peculiarly adapted to the conditions and circumstances surrounding the introduction of water-works in small towns, because its simplicity of construction renders it the least likely of disarrangement under the direction and supervision of a very ordinary mechanic and occasions the least expense for maintenance and repairs, and because economy of operation is of small consideration for the very few hours of service daily during the probationary period which serves to render a community acquainted with the convenience, nature, and value of a public water-service, and to accumulate the experi- ence and the proper appreciation of essentials that are necessary in the successful management of a water-works. An investment in more expensive and more complicated machinery than the simple duplex machine would sometimes prove unprofitable until proper experience had been acquired and the water-service had become extended and popular. Generally speaking, the inside metal-packed plunger-pump is preferred, and usually installed during the probationary period, for water-pressure under 150 pounds per square inch. Fibrous packing, sometimes substituted for metal plunger-packing, adds to the frictional resistance of the plunger in operation and accordingly reduces the mechanical efficiency of the machine. For pressures above 150 pounds per square inch it is found economical and much safer to approximate as nearly as possible a cylindrical form of construction of the pump-chambers, and accordingly the usual form of design is four cylindrically formed pump-chambers standing upright in pairs, and with a plunger working through two outside stuffing-boxes for each pair of pump-cylinders, as illustrated by Plate XV, page 103. These PUMP1NG-ENG1NES. *97 stuffing-boxes are fibrous-packed, usually with braided Italian hemp, and show any slip or leakage of water around the plunger. The double fibrous-packed plunger offers more than twice the resistance of the single inside metal-packed plunger previously described. However, this increased friction is unavoidable in high-pressure service and under careful mechanical supervision it need not be a large percentage of the total frictional resistance, which in high-pressure work is largely the pipe resistance of the force-main and distributing pipes. The inside-packed plunger possesses the further advantage of being able to sustain a higher vacuum on the pump suction-chamber than the outside-packed plunger, because the latter is continuously exposed to atmospheric pressure and will allow air to enter the suction-chamber of the pumps through an imperfectly packed plunger stuffing-box gland. The duplex pumps wih 1 often short-stroke; that is to say, they will sometimes run with a shorter stroke than that necessary to a full-capacity delivery of water. It is therefore customary to have a stroke-adjustment mechanism actuated by hand-wheels communicating by a spindle with the interior of the engine, by means of which an adjustment can be made to correspond with full-stroke delivery as soon as the engine after starting is well warmed and the pump is under full load. When the pumping-engine is working under heavy pressure it is a wise precaution to have attached to the steam-valve of the engine a water-pressure governor like the Fisher governor, which shuts off the steam upon a sudden faU of water-pressure like the bursting of the force-main or similar accident. The conditions of service in many towns require stand-pipe pressure for domestic service and direct pressure for fire service. In the one case the stand-pipe communicates with the distributing system of pipes, absorbs whatever water comes from the pumps in excess of the consumption and accordingly governs the pressure upon the pipe system; in the other case the stand-pipe is valved off from the distributing pipes and no more water can be delivered into the pipe system than that which is drawn out of it by con- sumption through the house service-pipes or fire-hydrants. Ac- cordingly in direct-pressure service the pressure upon the pipe 1 9 8 IV A TER-S UPPLIES. system may be increased through the operation of the boilers and pumps much above the ordinary stand-pipe pressure. But a compound duplex pumping-engine designed to work economically under a stand-pipe pressure cannot work in a similar manner under fire-service. This difficulty is overcome by providing a valve which when opened admits high-pressure steam into the low-pres- sure cylinder ordinarily using steam expansively, thereby convert- ing the machine into a simple engine using steam altogether at boiler-pressure. For the time being all concern to secure station economy in the use of fuel is abandoned in an effort to furnish prompt and efficient fire-service, and justifiably so, for the period of fire-service, always comparatively brief, is one which demands the protection of property exposed to destruction at any pumping- station expense of operation. A similar adjustment of rotative pumping-engines to the requirements of a variable service is made by means of an adjustable cut-off. It is usually customary to place a check-valve on the force- main near the pumps, but with doubtful propriety in small water- works when accompanied by a gate-valve, for the reason that a check-valve does not relieve a pump of water-hammer and is unnecessary to keep the pressure off of the pump-valves when the engine is not working, as it takes but a few minutes to close a stop- valve of 12 inches and less diameter; with water- works having large water-mains the situation is so entirely different that a multiple check- valve is indispensable. The pounding of the check may be a very disagreeable if not a dangerous feature usually experienced when pumps reach or somewhat exceed their rated capacity. A long force-main connecting the pumps with the distributing system is frequently exposed to a heavy water-ram, but it can be greatly relieved from the shock of the surging water by a relief- valve located usually in the pumping-station. Under some con- ditions of service where, for instance, a heavy static lift is required in order to reach a high elevation, and in addition where there is the resistance of a long force-main to overcome a relief valve is absolutely essential, particularly when the pipe-lines are small. A grade of pumping-engine next above that just described is the compound condensing duplex type. In this type of engine the PUMP1NG-ENGINES. 199 low-pressure cylinder is somewhat larger in proportion to the high- pressure cy Under than it is in the type previously described, thereby admitting of greater benefit of steam used expansively. The exhaust-steam passes into a condenser, where it is condensed and subsequently returned to the boiler or wasted, as the case may be. Local conditions usually decide whether a surface or a jet condenser can be most economically installed in connection with the pumping- engine. The saving of fuel through the higher expansion of steam in this type of pumping-engine and in the use of a condenser should increase the station duty fully 25 to 30 per cent. A second step in advance is the installation of a triple-expansion duplex or a horizontal compound fly-wheel pumping-engine of the condensing kind. Small units of either type of engine are now manufactured for small water-works where the average daily consumption does not exceed one-half million gallons of water, which the manufacturer will guarantee to give a test duty re- spectively of 70 or 80 million pounds of water raised one foot high with the expenditure of 1000 pounds of steam. These types of engines of the small units stated should give a station duty more than double that of the type of engines first described. In installations of large units the test duty will run over a hundred million pounds of water one foot high with an expenditure of 1000 pounds of steam, and the station duty becomes propor- tionately as high. Duties as high as 130 to 160 million pounds of water raised one foot high with the expenditure of 1000 pounds of steam may be obtained from double- or triple-expansion fly-wheel engines in pumping large volumes of water to a considerable height. Engines of this type are adapted for use in connection with the water- works of large cities which depend upon the constant use of the pumps for their water-service. They are expensive machines and require skilled mechanics as attendants. Very high station duties may be maintained with this type of engine working under favorable conditions, and very long life may be expected of massive, slow-moving, and self-contained pumping-engines of this type. The centrifugal or turbine pump actuated by a reciprocating en- gine is peculiarly adapted to low-lift work because of the cheapness with which such machinery can be installed in comparison with 200 WATER-SUPPLIES. economically working reciprocating pumping-engines. Installa- tions of this character are frequently recommended in connection with settling-basins and niters and numerous other uses of a similar kind. A few installations are to be found of high-lift turbine-pumps, but there seems thus far to be no substantial encouragement that they are capable of accomplishing heavy work as economically as the higher grades of the reciprocating pumping-machinery. Even in moderately low-lift pumping a well-designed reciprocating pump will work more economically than the centrifugal pump, assuming either type of pump to be operated by an equally efficient steam-engine. The only element of annual expense which will weigh against the reciprocating pump- ing-engine and in favor of the centrifugal pumping-engine is the interest on the cost of manufacture, transportation, and installa- tion. When this element of charge, taken in connection with the annual cost of operation and maintenance of the reciprocating type of machine, exceeds similar expenses in the aggregate of the cen- trifugal type of machine, the latter installation becomes the cheaper. When the lift is very low and very large volumes of water are to be handled periodically the centrifugal-pump installation becomes the more economical. The centrifugal pump as ordinarily manufac- tured is of comparatively low efficiency, and, so far as we may judge from the few reliable tests of such pumps, the efficiency is more often below than above 50 per cent, and sometimes as low as 35 per cent. Intelligent design and careful shop-work are neces- sary to produce an efficiency of 60 to 70 per cent. The centrifugal or turbine pump gives its best efficiency when running at a constant speed and delivering water against a uniform head and is therefore poorly adapted to that condition of service which requires occasional change from a reservoir delivery to a direct-pressure delivery. The rotary motion of this class of pumping-machinery pecu- liarly adapts it to a direct connection with an electric motor wherever occasion requires pumping by transmitted power. A pumping-engine of any grade does its best work when moving constantly at its rated capacity and delivering water against a steady pressure, as when delivering water into a reservoir. But reservoir-pumping warrants the installation of the highest grade PUMPING-ENGINES. 201 of pumping-machinery only when the volume of water-consump- tion is sufficient to require the continuous use of pumps of large capacity. When large-capacity machinery is so operated under skilled mechanical supervision it should give the highest attainable station duty. The same class of machinery operated under direct -pressure ser- vice gives a lower station duty because in a service of this kind the fluctuating rate of consumption produces a fluctuating rate of speed, and correspondingly a momentary fluctuation of duty which in the average is considerably below the duty of the machine moving uniformly at its best speed under steady reservoir pressure. As a rule it does not pay to install high-duty pumping-engines in localities where the water-lift is light and the daily period of service short ; besides the local cost of fuel is to a considerable extent an influencing factor. Small towns very properly install comparatively low-duty engines during the probationary period and gradually increase the duty of future installations as the consumption and hours of service progressively increase. The life of a pumping-engine depends upon the carefulness and intelligence with which it is operated and kept in repair, quite as much as upon the design and construction for the particular work which it is required to perform in daily practice. The wear and tear, or in other words the cost of maintenance, de- pends very much upon the simplicity of design of the machine, perfection of workmanship, rigidity of imporant parts, and stability of installation, and the rate of deterioration of moving parts depends in a great measure upon the number of reversals in any unit of time. That is to say, high-speed operation generally contributes in a greater degree to the cost of maintenance than does low-speed operation. The mechanical life of a machine which is under good attend- ance and is not overworked may be very long, but its actual life depends very much upon the rate at which it is called on to work. Whenever its capacity becomes exceeded or daily require- ments of work reach a point where the machine of itself fails simply because of incapacity, its usefulness as an independent factor becomes impaired although mechanically it may be altogether reliable. This situation can be met by the installa- 202 WATER-SUPPLIES. tion of larger machinery, but it does not necessarily require the complete abandonment of the older machine, which may yet per- form important and satisfactory service as a reserve machine. Instances arise where the actual substitution of one machine for another in the daily service produces a saving in station ex- penses which warrants the change regardless of the fact that the older machine may be thoroughly reliable mechanically, but the act of substitution cannot be interpreted as reflecting complete mechanical deterioration of the abandoned machine, so long as it remains a part of the station equipment and can be used in a secondary if not in a primary capacity. The benefit of the change is to be found directly in the decreased station expenditure result- ing from the use of the more economically working substitute for the heavy daily service. The complete abandonment of the older machine as a part of the station equipment will seem to be justified only when the extra expense of operating and maintaining it in a subordinate capacity, plus interest on the investment in its pur- chase and installation, is considerably greater than the sum of similar charges against an installation of a higher grade but more costly machine intended for work in a similar subordinate capacity. The basis of a guaranteed duty for some specified set of con- ditions is the proper basis for the purchase of pumping-machinery. But the basis of purchase is seldom adopted in the purchase of the small direct-acting pumping units installed in small water- works, for the reason that the volume of water pumped is so small and the daily period of service so short that the cost of the fuel consumed in actual pumping-service is small in comparison with the other annual station expense; frequently the saving in fuel resulting from the use of a more efficient type of pumping-machinery will not amount to the interest on the difference in cost of the two installations. However, as the volume of water pumped increases and the daily period of service lengthens, the need of a higher grade of pumping-machinery becomes necessary and apparent, and natu- rally the duty basis of purchase becomes an independent and usually a controlling consideration. The penalty for non-fulfillment of the duty guarantee some- times takes the form of a provision retaining a percentage of the PIMPING-ENGINES. 203 purchase-price until a proper test of the pumping-machinery in- stalled shall have demonstrated its ability and capacity to give the duty guaranteed of it; at other times a forfeit is demanded upon the basis of a specified sum to be forfeited for each one mil- lion foot-pounds of duty the work of the engine falls below the guaranteed duty. In this regard the manufacturer has good reason for insisting that a forfeiture provision of the latter char- acter should be balanced by a premium clause offering some speci- fied bonus for each one million foot-pounds of work the engine proves itself capable of performing in excess of the guaranteed duty. Unless there is some balancing provision of this character the forfeiture clause of itself may result in higher bids than would otherwise be the case. Such provisions, however, are customary, as a rule, with large and high-class pumping-machinery only. CHAPTER IV. IMPOUNDED SUPPLIES. THE flow of rivers and streams, the waters of which are of sufficient purity for use without purification, is usually less during certain periods of a year than the demands for water-supply pur- poses. To insure an adequate supply during periods of low stream- flow, the water of freshets and flows in excess of the consumption by the works is stored in impounding or storage reservoirs. These may be natural lakes and ponds, or artificial reservoirs formed by the construction of dams across the valleys through which the streams flow. In many instances artificial reservoirs are repro- ductions wholly or in part of ancient lakes. The water from a storage reservoir is to be preferred to that taken directly from a stream, inasmuch as the quality of a surface- water is improved by storage in a reservoir of sufficient capacity which has been properly prepared for service. The effects of pol- lution by organic impurities are more marked in instances where water is taken directly from a stream than where the supply is obtained from a large storage reservoir, since the period which elapses from the time of contamination to that of consumption in the first instance is usually insufficient to result in the elimina- tion of the germs of typhoid fever and other intestinal diseases. The fact that epidemics of typhoid fever have been due to polluted surface-water supplies taken directly from streams is at present well established, and no community supplied in this manner is safe from these epidemics when the catchment area of the stream is inhabited. In all probability pathogenic organisms do not multiply in water-supplies, and experiments made by biologists indicate that 204 IMPOUNDED SUPPLIES. 205 these organisms do not retain their vitality longer than one month in the water of a reservoir. Consequently storage reservoirs act as safeguards against epidemics of intestinal diseases. The period of quiescence which the water of a large reservoir undergoes is beneficial, since the turbidity of the entering water during freshet flows in particular is considerably if not entirely reduced as a result of sedimentation. The color of a water is also reduced by storage in consequence of the bleaching action of sun- light. This effect is shown by the following table.* TABLE SHOWING THE EFFECT OF LONG STORAGE UPON THE COLOR OF WATER. Average Estimated Percentage time re- average Locality. of water- shed above quired to fill the Color at main inlet. color of all water Color at outlet. Change. inlet. reservoir, entering months. reservoir. Boston, Reservoir 3 .... 79 i-3 I .OO 0.86 0.82 o 04 Reservoir 2 .... 97 0.4 I. 10 1.07 0.98 0.09 Lake Cochituate 40 8-5 0.86 0.58 0.25 0-33 Reservoir 4 .... 84 7-5 i .40 1.27 0.72 -55 (Ashland) Brockton Reser- voir 82 3-4 2.24 1.87 0.89 0.98 It should be noted that the color of a stored water is not materially reduced unless the period of storage is about eight months. The beneficial effect of long storage upon the color of a water is, however, materially affected by the condition of the reservoir bottom. When the reservoir site has been carefully prepared by the removal of organic matter and the entering water contains little or no matter in suspension the best results are secured. On the contrary when the bottom of the reservoir is muddy the color of the bottom layers in deep reservoirs is increased during the stagna- tion periods which are common to reservoirs of a depth greater than twenty feet. The following tables illustrate the effect of organic deposits in a reservoir upon the color of the contained water, f * Stearns and Drown. ' ' Discussion of Special Topics relating to the Quality of Public Water-supplies." Report of Mass. State Board of Health on Water-supply and Sewerage, Vol. I. 1889. t Boston Water Reports, 1892, pp. 96, 97. 206 WATER-SUPPLIES. COLOR OP WATER IN LAKE COCHITUATE AT DIFFERENT DEPTHS. (Depth 60-65 feet.) 1890. Surface. Mid-depth. Bottom. August 5 o.io 020 0.80 " II O.IO O.20 2.8O 19 0.15 0.30 3.80 26 0.15 0.30 2.80 September 3 o.io 0.30 2.30 " 9 o.io 0.30 2.60 COLOR OF WATER IN BASIN 4 (ASHLAND RESERVOIR) OF BOSTON WATER- WORKS AT DIFFERENT DEPTHS. (Depth 30-35 feet.) 1890. Surface. Mid-depth. Bottom. Augusts 0.50 0.50 0.50 13 0.35 0.50 0.60 " 18 0.40 0,50 0.80 26 0.50 0.45 0.80 September 3 0.40 0.40 0.70 9 0.40 0.45 0.70 The Ashland Reservoir was prepared by the removal of all the loam from the site, and at the time the samples were taken the bottom was composed of clean material. During the circulation periods the water of the lower layers of deep lakes and reservoirs is mingled with the nearly colorless water near the surface, thus changing the color of the entire mass. Not only is the color of the water affected in the manner indicated, but the quality of a water obtained from a reservoir containing organic deposits in contact with the water is injured in other ways. The water of the bottom layers coming in contact with organic matter during the period of stagnation is deprived of its free oxygen and becomes charged with organic matter in various stages of decomposition. This foul water when mingled with the upper layers gives rise to disagreeable tastes and odors due to the matter in solution and suspension, or to the organisms which derive their food-material from this matter. "The effect of the character of the reservoir upon the stored water is best indicated in a chemical analysis by the free ammonia, which is a product of decomposition, and the albuminoid ammonia, particularly the suspended portion of the latter, which indicates the abundance of organisms and other suspended organic matter IMPOUNDED SUPPLIES. 207 contained in the water." * Analyses of water from two cleaned and three uncleaned reservoirs in Massachusetts are given below. Date Number Ammonia Reservoir. Con d. it ion Date of collect- ot months Albuminoid. of filling. ing sample. between dates. Free. Total. Dis- solved. Sus- pended. r Cleaned April Aug. Boston, Reservoir i 1886 1887 16 o .0005 0.0339 No. 4 (Ashland) 1 " Aug. I 1888 38 . 000 3 0.0386 0.0354 0.0033 Cambridge, S t o ny Brook Reservoir . .. Aug. Aug. 1887 1888 13 O.OOIO 0.0388 0.0234 0.0054 Quincy Reservoir Uncleaned Dec. Aug. 1888 1889 8 o.oaoo 0.0466 0.0386 0.0080 i 44 Aug. 1 890 30 O.OIIO 0.0360 0.0373 0.0088 Lynn , Glen Lewis Pd. Uncleaned Dec. Aug. 1889 1890 8 0.0633 o . 0903 0.0746 0.0156 Lynn, Walden Pond Dec Aug. 1889 1890 8 0.0576 o . 0746 0.0560 0.0186 The reduction of color due to long storage and the effect of cleaning a reservoir site is shown by Figs. 33 and 34. The changes during a year in the color of the influent streams, the surface-water, and the water at the bottom of two reservoirs in Massachusetts a clean reservoir (Ashland) and an uncleaned reservoir (Lake Cochituate) are indicated on these diagrams. The micro-organisms producing disagreeable odors in water- supplies are not usually present in flowing streams, but find the most favorable conditions for their growth in the quiet waters of lakes and reservoirs. The extent of their development depends in large measure upon the available food-supply, and clean water stored in a clean reservoir presents the least favorable conditions for their existence. The nitrogenous matter contained in the water of the entering streams or derived from the bottom and sides of the reservoir itself affords means for their growth often in considerable numbers. Even if the reservoir site be carefully prepared, the water entering the reservoir from an inhabited catchment area, although perhaps thoroughly purified, usually contains nitrogenous material, and a storage reservoir is rarely free at all times from micro-organisms. The experience in Massachusetts has been that trouble due to taste and odors of water-supplies is greatly reduced by the removal of material containing more than four per cent organic matter * Report of Mass. State Board of Health, 1890, p. 33. 208 WATER-SUPPLIES. from the reservoir sites, or the covering with clean sand and gravel of deposits too deep to be economically removed. Shallow margins are avoided either by excavating material until a sufficient depth 3 1 I Color of Water in Ashland Reservoir 1903 FIG. 33. is secured, or filling along the shores to make clean beaches. The excessive growth of grass and weeds along the shores during periods of low water is thus avoided. IMPOUNDED SUPPLIES. 209 In addition the quality of the water entering a prepared reser- voir is improved by measures taken to drain swamps upon the catchment area, to provide for the interception of surface- and ground-water before it reaches these swamps and its conveyance to the reservoir, and for the disposal or treatment of sewage from buildings upon the area of catchment. 10 Color of Water in Lake Cochituate 1903 FiG. 34. In the case of natural lakes or ponds which are subject to periods of stagnation and circulation, the effect of these occurrences upon the quality of the water is usually not so marked as has been indicated with respect to artificial reservoirs. Indeed, the view is often advanced that the stripping of a reservoir site is an item of unnecessary expense inasmuch as in course of time through the dissolving action of the water the bottom of a reser- voir will approach a condition similar to that of a natural lake. 210 WATER-SUPPLIES. The length of time required to accomplish this end is, however, very uncertain, and unless the benefits of stripping are liable to be impaired by deposits washed into the reservoir by freshets it is considered advisable to expend funds for the purpose of removing objectionable material from the bottom and sides of an impound- ing reservoir. An objection to a supply of water from a shallow impounding reservoir is based upon the comparatively high temperature of the water during the summer months. The temperature of the upper 80 TO ^60 .d I I* 1 J? 4 30 20 ! I 1 1 I 1 ! 4 fill / "^s ^ / ^ \ i / * >; \ \ ^ /- ^' *^ot toSL. _\ \ ^.^^ '/ \ Temperature of Water in Lake Cochituate FIG. 35. layers is favorable to the growths of objectionable organisms, and unless the reservoir is clean, water cannot be advantageously drawn from the cooler layers near the bottom even when the reservoir is deep. The warm water Irom a shallow reservoir is not looked upon with favor by consumers, as the water, even if un- affected by organisms producing tastes and odors, is not very palatable unless cooled. Owing to the evaporation losses from large areas of water-surface and the high temperature of the water of shallow reservoirs during warm weather, impounding reservoirs should be constructed of considerable depth. The capacity of an impounding reservoir in any given instance IMPOUNDED SUPPLIES. 21 1 is dependent upon local conditions, the amount of storage to be provided being computed from actual or estimated figures for yield and consumption. The yield used in these computations should not be the average yield of the catchment area under consideration, but the yield during a dry year or a succession of dry years. In the absence of definite information regarding the rainfall on or run-off from a catchment area, comparisons are made with areas for which suitable records are available. In mak- ing these comparisons, allowances are made for differences due to topographical and geological conditions affecting the yield of the respective areas. Such conditions are the relative altitude of the areas, distance from the sea or large inland lakes, and the proximity of mountain ranges, etc., as affecting the rainfall; the size of the catchment area, character of vegetation upon the area, extent of forests, general slope of surface, amount of impervious surface, character of the material composing the different strata, tempera- ture of the air, etc., as affecting yield. Furthermore, the losses by evaporation from the water surfaces in the area, and the losses due to percolation or seepage from the reservoir and the area itself are considered. Tables or diagrams are prepared giving the actual or estimated rainfall, run-off, consumption, evaporation, and other losses by months from which the amount of storage required is computed. The danger of using average values for rainfall and yield in storage computations is shown by the table of statistics for the Sudbury catchment area. The average results obtained from 1875 to 1904, figures for the two years in which the yield was the lowest recorded and figures for the year in which the yield for six months was a minimum, are given in this table. The fluctuations during the period covered by the observations are shown in Fig. 36. The matter of storage on the Sudbury area has been carefully studied by the engineers connected with the Boston works, and the results of these studies are contained in Mr. Fitzgerald's paper on " Rainfall, Flow of Streams, and Storage." * The diagram of storage capacity is prepared from that given in the paper mentioned and is applicable to catchment areas in New England comparable * Trans. Am. Soc. C. E., Vol. XXVII. 212 WATER-SUPPLIES. oooooooooooo oooooooooooo oooooooooooo OO M IO M HVO ON IO Tj- IO ^ O CQCOONHVOMCOONMOW co W 10 vo | M co C* OJ M Tj- W (N 10 M M HTflOCOWOlON 00 N O 10 M M POO vO O N ON OOOOOOO OOOOOOOOOOOO oooooooooooo oooooooooooo 10 ro w O *^* O ^^ ON w ^O *O *s^ M t^. ONOO O O\ 8 8 r^. rf- co O coco o O r^ M ^- 10 iOO CO COO 10 W M M co co co OwNMOOOOOOO M t^OO oo oo t^oo M oooooooooooo oooooooooooo oooooooooooo O t^ ^f O\ rt- iO\O ON O N to OOOVOMMOMM COCO 10 M O Ov^O ONCOCON M M COCO NWOWOOOOOOOO fOcorofOw cs\O rf- w COM oooooooooooo oooooooooooo oooooooooooo COMCOVOOO M ONONCOOOOO MVOCO M 1 x \ x \ / \ / S s^_ ^" c \ / 60 ~ t s J50 , \ / ' \ 7 ' V 7 \ / \ / \ x \ x \ r _ / \ / \ ^ \ 7 \ / \ \ / \ / \ / \ / \ O 2 30 i 2 f i \ / \ I ^ ^ \ / - ..-- \ ^ / \ s ^^ X / 5 \ x V S \ ' ^"^ Millioup o Li illons p^rS qu arqMile FIG. 36. Diagram of Yield of the Sudbury River Catchment Area. Catchment area: 1875-1878= 77.764 square miles 1879-1880=78.238 ' 1881-1905= 75.2 Per cent of water-surface: 1875-1878= 1.9% Increased in 1879 to 3.0% " 1885 " 3.4% " 1894 " 3.9% cession, ... it is impracticable to secure more than about 750,- ooo gallons daily from i square mile of watershed containing 10 per cent of water-surface."* To secure this supply a storage * Trans. Am. Soc. C. E., Vol. XXVII, p. 268. ("Rainfall, Flow of Streams, and Storage." Fitzgerald.) 214 WATER-SUPPLIES. capacity of about 222 million gallons per square mile is required. This is equivalent to about 56 per cent of the average annual yield. oo 0s 001 009 OSS Q fe o 0985 ^ s 008- OSS 002 -g cr 1 I DOT. o The effect of varying percentages of water-surface upon the area of catchment is clearly shown by the diagram, and the extent of water-surface should be kept below 10 per cent of this area whenever practicable. In the case of natural lakes and ponds in IMPOUNDED SUPPLIES. 2*5 10 20 Sole of Feet 30 40 50 60 70 80 90 100 X:.'v-:-ff E-15.8 MAXIMUM SECTION OF NEW C.ROTON DAM. FIG. 38. 2 1 6 WA TER-SUPPLIES. New England where the proportion of water-surface is compara- tively large, the available storage may be from one to one and one-half times the average annual yield. Dams or embankments are a feature of all artificial reservoirs, and often the selection of a reservoir site depends upon the practi- cability and cost of the necessary structures to retain the water therein. Provision is also made for the disposal of the water from freshets which cannot at all times be stored. Unless the main dam is designed to pass water, which is not usually the case with any but very low structures, masonry spillways or waste- weirs should be constructed of sufficient capacity to waste the water from the maximum known, or anticipated, flood without danger of overtopping the dam. The site of the spillway depends upon the topography of the valley in which the reservoir is situated and the proximity of the bed-rock to the surface. When the dam is of considerable height the spillway is located at one side of the valley if possible, with its crest from six to twenty feet below the top of the main structure. Dams of a height exceeding about seventy-five feet, when built in connection with reservoirs of considerable extent, are usually constructed of masonry. The masonry may be rubble, concrete, or cyclopean faced with ashlar or concrete blocks to make a neat finish. The foundations of high masonry dams are carried to sound bed-rock. Fig. 38 shows a typical cross-section of a modern high masonry dam, the New Croton, which is the highest yet constructed. Rock-fill dams have been used in some instances in the West where cement could not be economically procured. Dams of this class are made more or less water-tight by a facing or core of con- crete, timber, or protected steel plates. Earth is largely used in the construction of dams and embank- ments, gravelly earth being considered the best material for this purpose. Earth dams are, or should be, provided with a core-wall of masonry unless the bank is of unusual thickness and in no danger of ever being overtopped. The core-wall is usually of concrete and is carried to bed-rock on the bottom and sides of the valley when this can be done with economy. Otherwise the core-wall is founded on hard-pan or other impervious material. Sheet-piling has been IMPOUNDED SUPPLIES. 217 used in some instances beneath the core-wall when the rock was at a considerable depth. FIG. 39. Cross-section of Earth Dam. Earth dams of ordinary height vary in thickness from 12 to 30 feet at the top and have side slopes from i J : i to 3:1. The top is usually from 6 to 10 feet above high-water level. The slopes on the water side are paved with stone to the height reached by waves, and the down-stream slopes are sodded or faced with loam and sown to grass. When the height of the embankment exceeds 30 to 40 feet a berm is generally built at about mid-height on the water side to guard against the slipping of the stone paving. A similar berm is also placed on the down-stream side to prevent washing of the material by rains. Below the berm on the water side the slope is often riprapped with heavy stones as a substitute for the paving. The outlet-pipes from the reservoir and the controlling-valves are placed in gate-towers or chambers which are usually built in connection with the masonry portion of the dam or, in the case of earth embankments, as independent structures. PART II. MAINTENANCE AND OPERATION. CHAPTER I. PLANS AND RECORDS. AN important requisite for the successful management of a system of water-works is a complete set of plans and records. These should be accurate, should be kept up to date, and should admit of ready interpretation. Dependence should not be placed upon scattered and fragmentary notes in numerous field and office note-books, nor upon the memory of any person or persons having charge of, or connected with, any portion of the works. The value of such plans and records may not be apparent at the outset, but the changes which inevitably take place through the growth of a community, with the resulting obliteration of old landmarks, the relocation of street-lines, the changes in the per- sonnel of the department, and so on, very soon indicate that funds expended for the proper preservation of data have been expended wisely. Construction Plans. In the case of surface-water supplies, maps or plans should be prepared, upon which are indicated the source of supply, the catchment area, all water-surfaces, buildings, dams, and intakes. These plans or notes thereon should furnish information regarding 218 PL/INS AND RECORDS. 219 the size of the catchment ^area, and the extent of water-surface at varying elevations for use in making computations of yield. Detailed plans of all pipes and appurtenances in, and in the vicinity of, gate-chambers, pumping-stations, filtration-plants, reservoirs, and stand-pipes are to be desired. Accurate plans of the distribution system should be prepared from surveys made, or based upon measurements taken, during the work of construction. These plans may vary in character from the carefully drawn atlas sheets on a scale of forty or fifty feet to the inch, upon which are indicated the main pipes, valves, hydrants, plugged branches, service connections, street- and curb- lines, and all buildings, to the single sheet upon which main pipes, valves, hydrants, and street-lines alone are shown on a scale which will admit of the plotting of the distribution system upon a single plan, as the funds available for this purpose may determine. The record plans should preferably be made upon heavy paper mounted on linen, as plans on tracing-cloth are not very durable and in addition cannot be accurately scaled owing to the shrinkage of the material. Copies of the plans in the form of tracings or blue-prints made therefrom may, however, be of service. The several sizes of pipe may be indicated upon the plans by inks of different colors, valves by short heavy black lines at right angles to the pipe-line, and hydrants by small circles. In suburban localities where street-lines are not marked by monu- ments, or are otherwise not plainly defined, the travelled way may be shown to advantage by light dotted lines. A skeleton plan of the entire distribution system, either drawn to scale or carefully sketched, with the main valves indicated will be found useful for many purposes, especially in connection with a valve-location book. In order that the valves on street-mains may be quickly located in time of need, a valve-location book is indispensable. .Where valves are set on the street-lines, tie locations may not be necessary when the distance of the valve from the line of the side street is known and both street-lines well defined, but usually locations by ties to permanent objects are advisable. A sketch of the immediate vicinity of the valve should be made, and measure- ments taken to the box-cover from the corners of adjacent build- 22O MAINTENANCE AND OPERATION. ings, trees, hydrants, light-poles, etc. At least three ties should be taken from objects, as noted above, which are not likely to be covered by snow, the distances measured being preferably such as may be made within the limits of a fifty-foot tape. Copies of the sketches should be made upon tracing-cloth and the measure- ments with the points from which they are to be taken clearly indicated. Blue-print sets of valve locations can then be bound in book form for convenient use. The size of the sheets should admit of the carrying of the book in the pocket, sheets four by i H CO Tree ti I 2 J III A S) i j I s * Light Post 0- .- f^-" J '> ^Hjdra'nt ^ vtxjT MAIN ST. FIG. 40. Sketch of Location of Main Valve. six inches being suitable for the purpose. In cities a departure from the method of measurements outlined may be made by marking points at equal distances from the valve-box by bolts in, or circles marked in paint on, adjacent buildings. Similar tie-locations may be made of plugged branches with the addition, of notes indicating the distance of the branch from the nearest valve or hydrant branch. Since service-pipes as a general rule are laid at right angles to the axis of the street, the curb-cock alone may be located by measurements from the corners of the building to which the pipe is laid or from other convenient objects. The diagrams of the services and the ties to the service-boxes may be made upon cards PLANS AND RECORDS. 221 which are filed alphabetically, according to the name of the property owner or occupant of the premises, or by streets and numbers, at the option of the official in charge of the work. The corporation cock or tap may be located by similar measurements if desired, or both curb and corporation -cocks may, in the case of isolated buildings, be located by distances along, and offsets from, the line of the building produced. This latter method of location, however, possesses no advantages over that first mentioned, and \ FIG. 41. Diagram of Service Connection. relocations cannot be made as accurately as by the use of measure- ments which intersect at a point. Construction Records. The plans of a system should be supplemented by records kept in specially designed books, on sheets preserved in loose-leaf binders, or by the card system. The first method is preferable for the preservation of data regarding street mains, valves and hydrants, and the second or third in the case of service connec- tions, particularly when the service application and data are entered on a single form. In addition to the statistics of original construction, information respecting alterations, renewals, and discontinuances should be recorded. 222 MAINTENANCE AND OPERATION. The record-books may be arranged in such manner that informa- tion concerning the separate items may be placed on a horizontal line; the data being entered under appropriate headings printed above vertical columns covering two opposite pages of the book, or one page if an oblong book is used. The following headings are suggested for main-pipe, valve, and hydrant records: Main Pipes: Street; Location; Length and size of main (separate columns being used for the several diameters of pipe used) ; Distance from street-line; Material; Number of valves; Number of hydrants; Length and size of hydrant branches; Length and size of blow-off branches; Cost pipe, specials, valves, valve-boxes, hydrants, lead and yarn, labor, teaming; Date of completion, etc. Valves: Street, Location; Size (separate columns being used for the several sizes); Type of valve; Maker; Turn to open, etc. Hydrants: Street; Location; Size of main; Length and size of branch; Number and kind of nozzles; Type; Maker; Turn to open, etc. The service records may be entered on printed sheets or cards, the service application and data appearing on one side of the form, the reverse being used for the diagram. These records should furnish information upon the following points: Owner and Occu- pant of Premises; Street and Number; Material of service-pipe; Diameter; Length main to curb-cock, curb-cock to street-line, street-line to stop and waste; Total length; Number and size of taps; Date of completion; Cost corporation-cock, stop-cocks, service-box, pipe, labor, teaming, etc. The items of cost may be divided in order that the respective costs within the limits of the street and in private property may be ascertained in cases where bills are rendered the property owner based upon actual expenditures for construction outside the limits of the street. A specimen service application and record is shown on the following page. The sheets are 8 xioj inches in size and are filed in loose-leaf binders. PLANS AND RECORDS. 223 TOWN OF CONCORD: WATER DEPARTMENT. Service A pplication . SERVICE No CONCORD, MASS To the Water and Sewer Commissioners: The undersigned hereby applies for a supply of water for the premises on Street, owned by and occupied by as a and hereby agree to conform to all rules and regulations now or to be established by the Commissioners. Applicant RECORD OF SERVICE. COST WITHIN STREET. COST WITHIN PRIVATE PROPERTY. Foreman $ Foreman $ Labor Labor Team Team ....ft in pipe@ . . . .ft . . . .in . . . .pipe @ Stop and Waste Cock Stop and Waste Cock .... Corporation Cock .... Service Box Supervision and Use of Tools Total Total $ . . DIAGRAM OF SERVICE. Kind of Pipe Size of Pipe Main to Stop Stop to Line Line to Stop and Waste Total Length Number of Taps Service Completed Bill Rendered Bill Paid Remarks Maintenance Records. Whenever possible, data with regard to the yield of catchment areas from which surface-water supplies are obtained should be systematically collected and recorded. Observations of the pre- cipitation at one or more points on the area, of the elevations of the water-surfaces of ponds, lakes, or impounding reservoirs on the area of catchment, of the quantities of water drawn from the 224 MAINTENANCE AND OPERATION. area for use in the works, and of the amount flowing off in streams are necessary for this purpose. The measurements of precipitation should be made with a standard gage. The instruments adopted by the U. S. Weather Bureau are described and directions for their use given in circulars published by that Bureau. (Measurement of Precipitation, U. S. Dept. of Agriculture, Weather Bureau, 1903; Instructions to Observers, U. S. Dept. of Agriculture, Weather Bureau, 1903.) The standard gage of the Weather Bureau is shown by the accompanying illustration. This gage consists of a receiver (A) which is 8 inches in diameter inside, a measuring- tube (C) of such FRONT VIEW VERTICAL SECTION ^ a VAX 1 ^n^ d B 7* d B c HORIZONTALjSFCTION E-F B Scale of Inches 10 11 12 13 14 15 10 17 18 19 20 21 22 23 24 FIG. 42. Standard Rain Gage. diameter that the depth of rainfall collected is magnified ten times, a graduated measuring-stick and an overflow attachment (B), in which rainfall in excess of the capacity of the measuring-tube may be collected. Rainfall is measured in inches and decimals of an inch, and precipitation in the form of snow is recorded in equiva- lent inches of rainfall. Snowfall is collected in the overflow attachment of the gage and carefully melted. Observations of precipitation should be made daily. The gages are preferably exposed in an open space and at a distance from trees, buildings, or high fences. "Low bushes and fences, or walls that break the PLANS AND RECORDS. 225 force of the wind, are, however, beneficial, if at a distance not less than the height of the object." The top of the gage is placed level and about three feet above the ground. The elevation of the water-surface of ponds, lakes, or storage reservoirs should be observed periodically, and the increase or decrease in the amount of water in storage computed from the results of these observations and the data regarding the extent of water-surface at different elevations. Tables or diagrams that indicate the volume of storage corresponding to stated elevations of the water-surface are useful in this connection. The draft from the catchment area is ascertained from pump- ing or meter records, or observations of the flow of water over weirs. The first-mentioned records are likely to be seriously in error, unless the slip of the pumps be known and provided for in the computations of pumpage. The ordinary type of water-meter is not, as a rule, used for the measurement of the total volume of water supplied to a city or town; the Venturi meter, an instrument devised by Clemens Herschel, C.E., being used for this purpose. The Venturi meter consists of a contracted tube composed of two truncated cones and a throat-piece which connects the smaller ends of the former. This tube is placed in the pipe-line. When water is flowing through the tube, the velocity of flow is greater at the throat than at the up-stream end of the tube, and the pressure at this point is less than that at the latter; the difference in pressure being dependent upon the quantity of water flowing. The loss of head due to the contraction of area of the pipe is, under ordinary circumstances, insignificant. The up-stream end and the throat of the meter- tube are connected by pipes with a recording-apparatus, which mechanically integrates the varying relations of velocity and pressure within the tube, and indicates on a dial the amount of water which has passed through the meter. By the addition to the register of a chart-recorder the rate of flow at intervals throughout the day is recorded upon a strip of paper. The com- mon sizes of meter are from six to sixty-inch, and the meters are designed to measure flows when the maximum rate does not exceed about ten times the minimum rate of flow through the supply-main in which the meter is placed. The results obtained 226 MAINTENANCE AND OPERATION. by Venturi meters operating under suitable conditions are accurate within about two or three per cent. Forty-nine Venturi meters were used in investigations made by the Metropolitan Water and Sewerage Board in 1903; the arrangement of the meter and regis- tering-apparatus as generally used being shown in Fig. 43. Water-tight Steel Chamber containing I Meter Register placed under sidewalk I Venturi Meter Tube A. Chart-box and Chart B. Weight for operating register mechanism. C. Cylinder containing float and integrating mechanism. Scale of Feet FIG. 43. Venturi Meter and Register Chamber. (Jour. N. E. Water-works Assoc'n, Vol. XVIII, p. 113.) The flow of water over weirs or dams is computed from obser- vations made of the height of water above the crest of the weir or dam, by the aid of formulas adapted for use with the condi- tions which obtain in a given instance. The yield of or run-off from a catchment area is dependent upon the precipitation upon the area, and the evaporation from the land and water surfaces. The amount of water available from the area is determined from the computations of yield or PLANS AND RECORDS. 227 run-off; these computations being based upon the observations of the quantity of water in storage, the draft, and the waste over dams or waste-weirs. This amount varies from year to year, and since the capacity of the source is dependent upon the minimum yield and the opportunities for storage, records extending over a period of years and embracing varied conditions are of great value when observations are accurately made and the data care- fully compiled. The average results obtained from observations made on some existing works are of interest in this connection and are given in the following table. AVERAGE YIELD OF CATCHMENT AREAS. Stream. Period covered by observations. Catchment area. Square miles. Average Rainfall. Inches. Average run -off. Inches. Sudbtiry l87 10 Ov 4k O M M IH M 00 ON4k K> O OOON4* Nominal diameter of pipe. M M O O O O O O 0000 tj* Thickness w of shell. > M O O 00 SLLL2 ^J -0 O\ ON M 4- cyica O 4k 4k Oo OJ ~-I K> 00 4^ OO-vJ ON4k vO Oi M vo O MO* U 0000 Os> IO (0 M 00 00 O ON O C\C/l w 0000 4k w O 00 O M M M O en O O ON4k Oo K) 01 ^J GJ O O 01 O O g Weight per $ length. M M W 11 O O Ol o fc 1 Thickness 3 of shell. to C* M M O 0000 O 00-vj ON -i 10 ON ON ONC/T C/l Cs> O ^J OJ HI O CO ONOi Oo ONvO Oi O ^r 0\ O O O O 4k Oo K) M 13 M K> ^J ^J C*> \O ON o o o o ca OJ O 00 K> O CCOt O O O en ON 00 O C Weight per w length. M W M M M O O O O O o o o o V Thickness 3 of shell. Q P I (/!<* k IH O ^J Oi O-> O O 00-vi K> M ON ON ONCa O Cn I-" *si 01 4k 4k Co Oo 00 W CN M vo ^-T ON VO OO\O K> O O M *N o o o o K) Go Ol M O O O ox Weight per y length. 00 ONC^I vO -t- O <-n w O O O O ONU> M VQ ONVO 01 M O O O O O Ol ON ET Thickness p of shell. Q P K O *O4k M O 4k O ^J w O OO^J OJ M OOVO ^j ^i ON ON On O ^ M Oo O 00 ON Oo \O ^J vo 8O Oo- Ol O K) M vo 00 Cn O c^i c_n Oo^r ^i ON O Ol O Ol ONOi 4k Oo O Oo CNO M M Oi K> vo ^J IH 4k -^j ^ 8O 4k K> O O O trt 4k CA* \O OJ O K> O 4^ ON 0000 \O ONOo O M M M 4k 0000 OCOl OO K> M ^1 OOOO O Oi O O 5 Weight per w length. o o o o O ON Oo a' Thickness of shell. Class F. M \O ~-J Ol O O O Oo Cs> K3 O O ^I O Oo M 00 OO^J ON ON O 01 O CNOo O 00 Oi Oi CNOo O ON 0000 ON4k CA> (0 4k ^i M 4k 4k K> 0000 (0 M M M O "^i Os> M 4k IH vo O O O O O 00 Ol o Weight per y length. OOO OOOO Sr 1 Thickness y of shell. Class G. Oo^r ^r Oi O OJ ONOl Ol 4k >-J OO O K> 004. M M ON ON 000 Oo r K> vo 4k M Oi OOOO ^ Weight per w length. OOO vo oo-^r O OJ ^J o >J o V Thickness 3 of sheU. e B K VO Oi K) O C*> 000 vO Oo 01 C Weight per y length. 000 ONOi 4k Oo 4k Oi a" 1 Thickness ." of shell. Class I. ON4k M 4^ Cx O Ox Oi C Weight per ? length. O 4k 00 3 1 Thickness of shell. o I w to 00 O Weight per ? length. 242 MAINTENANCE AND OPERATION. FIG. 50. Section of Eddy Hydrant. FIG. 51. Chapman Hydrant. FIG. 52. Mathews Hydrant. EXTENSIONS. 243 Post hydrants provided with two 2|-inch hose nozzles and one steamer nozzle will usually prove satisfactory for general use. Frost-cases may usually be dispensed with, but are occasion- ally needed when hydrants are set in clay soils. The valves used in street-mains are usually iron-body valves with bronze mountings, the wedge of which is operated by an inside screw. Valves made entirely of iron are not suitable for FIG. 53. Ludlow Hvdrant. FIG. 54. Corey Hydrant. FIG. 55. Walker Hydrant. water-works use. The upper end of the screw or stem is capped with a square iron nut, and the screw is turned by an iron or steel rod with a socket on the lower end which fits over the nut, the latter being made accessible by the use of a cast-iron valve-box. The pattern of wedge used is the chief feature of difference in the various makes; the wedges of certain valves being cast as a single piece, and those of others consisting of two or more parts which are held together by the stem. Valves provided with a divided wedge are termed "adjustable-wedge" valves. 244 MAINTENANCE AND OPERATION. The smaller valves are usually placed in a vertical, and those larger than eighteen inches in size in a horizontal, position. In the latter cases gearing is required for the operation of the valve. The largest valves are provided with a by-pass by which the pres;- FIG. 56. Section of Chapman Valve. FIG. 57. Coffin Valve. sure on the sides of the wedge is equalized when the valve is opened, and are enclosed in masonry manholes. Sectional extension valve-boxes are placed over the smaller valves. Three designs of boxes are shown. Boxes composed of sections which have no mechanical connection are preferable in streets where the traffic is heavy, as the boxes with sections having threaded joints are more easily broken by road-rollers and heavy teams. EXTENSIONS. 245 Estimates of Cost. Estimates of the cost of proposed work are based upon the prevailing prices of materials and the wages paid in the locality A-Case B- Cover or Bonnet C-Stem or Spindle D-Packing Plate or Stuffing Box E-Stuffing Box Gland or Follower M GG- Gates H- Gate Rings I -Case Kings J Top Wedge K Bottom Wedge |_ Throat Flange Bolts M- Stuffing Box or Follower Bolte FIG. 58. Section of Ludlow Valve. where the work is to be done. The preparation of estimates of cost is facilitated by the use of tables or diagrams. The cost of cast-iron water-pipe is the principal factor in computations of cost of pipe-lines, and this cost is usually from $25.00 to $30.00 per ton, but often the quotations, particularly for the smaller sizes, exceed these figures. Fig. 61 shows the cost per foot at varying prices 246 MAINTENANCE AND OPERATION per ton of 2000 Ibs. of the several sizes of cast-iron water pipe from 4 to 24 inches in diameter, included in Classes A, C, and E of the New England Water- works Association. A similar diagram based upon the actual weights of pipe in use in A-Stem Nut B Stem C Follower D Follower Bolts E- Stuffing Box F- Cover G-Body H Body and Cover Bolts I Ball J Gate K Gate Ring - Case Ring FIG. 59. Section of Eddy Valve. a given instance can be readily prepared and will often be found convenient in estimating. The value of the diagram will be increased if to the cost of the pipe per foot be added the cost per foot of pipe-laying, etc. The latter may be ascertained from figures obtained from actual work previously performed, and three lines may be drawn upon the diagram for each size of pipe: one EXTENSIONS. 247 representing the total cost per foot when the excavation is con- sidered easy, one when this is difficult, and a third when average conditions are encountered. The cost of excavating, back-filling, and pipe-laying per linear foot of trench under the average conditions which obtain in small cities and towns in New England is about as follows: Size of pipe, inches. . ..4 6 8 10 12 14 16 18 20 24 30 Cost per foot, cents.. .. 18 21 25 30 35 42 50 60 70 95 $1.30 FIG. 60. Valve-boxes. The cost of rock excavation averages from 83.00 to $4.00 per cubic yard. From ij to ij Ibs. of lead are required for each inch of internal diameter for making joints in cast-iron pipe lines; i.e., the lead required for a 6-inch pipe- joint varies from about 7^ to loj Ibs. The pig lead used for joints costs from 4^ to 5 cents per pound. The amount of yarn required for joints varies from 0.05 to o.i Ib. per inch of internal diameter. The cost of yarn or jute is from 4 to 4J cents per pound. Valves for water-mains cost about as follows when purchased in small quantities: Size, inches 46 8 10 12 14 16 18 20 24 $6 $10 $14 $22 $28 $44 $60 $80 $100 $140 Cost \ to to to to to to to to to to $8 $13 $20 $28 $36 $54 $75 $100 $125 $180 MAINTENANCE AND OPERATION. Valve-boxes cost from $2.75 to $4.00 each. Post hydrants with 6-inch connections, two 2 J-inch hose nozzles and one steamer nozzle cost from $25.00 to $31.00 each. Frost- cases are from $2.00 to $3.00 additional. 8 S L 1 **> s qooj *B(L adi j jo ^s.oo FIG. 6 1. Cost of Cast-iron Pipe. Special castings are either sold by the piece at varying rates of discount from established lists or by the pound at the market price for castings. CHAPTER III. SERVICE CONNECTIONS. THE link between the street-main and the interior piping on the premises of the consumer is the service connection. As a measure of precaution against possible leakage due to poor workmanship, FIG. 62. Hall Tapping-machine. imperfect fittings, or the use of pipe of inferior grade, and un- authorized connections, made either with the mains or under- ground service-pipes, all service-pipes and fittings from the street- main to and including the stop and waste cock on the applicant's premises should be furnished, laid, and maintained by the water department. A proper charge may be made the consumer for the portion ot the connection which is outside the limits of the street or way, and an additional charge, if such is the custom, for the tap and street connection. 249 250 MAINTENANCE AND OPERATION. The service connection consists of the tap or corporation cock in the main pipe, a lead gooseneck, a curb-cock with suitable box, a stop and waste cock on the consumer's premises, and all intervening piping. The main pipe is tapped and the corporation cock screwed in place by a tapping-machine designed to operate with the main under pressure. There are several good machines for this purpose on the market, one of which is shown in Fig. 62. FIG. 63. Service-clamp (Mueller Pattern). The check on the tap and drill should be adjusted to allow the corporation cock to project through the pipe wall about one-half to three-quarters of an inch, otherwise the tuberculation, which takes place on the interior of the main more rapidly at this point as a result of the injury to the protective coating, will slowly but effectually close the opening. The corporation cock is usually of the same diameter as the service-pipe, but as it is inadvisable to make large taps in small mains, since a good contact between the threads on the cock and in the main is impossible and the resulting joint possesses little strength or rigidity, it is occasionally necessary to make several taps and combine the goosenecks when large service connections are laid. The use of several taps may be obvi- SERVICE CONNECTIONS. 251 ated by the use of a tapping-band or service-clamp, which insures that the corporation cock will be held firmly in place. These bands are drilled and tapped for the reception of the corporation cock, bolted about the main pipe, and the connection made in the usual With Straight Coupling. With Bent Coupling. FIG. 64. Corporation Cocks. manner. Leakage is prevented by the use of a rubber gasket, and cement or lead placed in a groove cast in the band. As a general rule the smaller mains are tapped on top, and the Wiped Joint Cup Join* FIG. 65. Gooseneck. larger on the side. In the first instance corporation cocks with bent couplings are used, and in the second, those with straight couplings. FIG. 66 Corporation Cock with Lead Flange-coupling. Unless lead pipe is used for the service, a lead gooseneck about two feet long is placed between the corporation cock and the service-pipe, care being taken that the upper portion of the 252 MAINTENANCE AND OPERATION. bend is not placed too high in localities where the ground freezes near the main pipe. The gooseneck is provided as a safeguard against excessive strain, due to the settlement of either main- or service-pipe resulting from excavations for sewers or drains. The joint between the corporation cock and the gooseneck may be made with solder, either a "wiped" or a "cup" joint being Stop and Waste Cocks for Iron Pipe. Stop and Waste Cocks for Lead Pipe. Union-joint Stop and Waste Cocks for Lead Pipe. FIG. 67. Stop and Waste Cocks. made, or the solder may be omitted and the connection made with a lead flange-coupling. The "wiped " joint presents a more workmanlike appearance, but the "cup" joint when properly made has given entire satisfaction and requires less labor and material. The lead flange-coupling consists of a special union in which the end of the lead pipe is spread and flattened with SERVICE CONNECTIONS. 253 suitable tools to form a gasket for the joint. The material costs about the same as that for the " wiped " joint, but the joint does not require the skilled labor necessary in the latter instance. The corporation cocks and the stop and waste cocks should be substantially made, turned, and bored in a workmanlike manner, and should be of the type known as " round way." The mate- rials entering into their composition and the proportions used at Providence, R. I., are as follows:* 80 Ibs. copper; 6 Ibs. tin; 3 Ibs. zinc; 2 Ibs. lead. Mr. William R. Hill recommends a mixture of 88 parts refined copper, 6 parts tin, 3 parts zinc, and 3 parts lead with the pro- FIG. 68. Section of Inverted-key Stop and Waste Cock. FIG. 69. Compression Stop and Waste Cock. viso that ' ' if there is alkali or salt in the soil the zinc should be omitted on account of corrosion." Also that " the plugs should be lubricated by plumbago and Albany grease or vaseline. Bees- wax and tallow should not be used, as it will get hard and make it difficult to open or close the valve." f One objection to the ordinary plug-cock is overcome in the "inverted-key" type. * Jour. N. E. Water-works Assoc'n, Vol. XVIII, p. 24. t/wa.,Voi. xin, PP . 37,38. 254 MAINTENANCE AND OPERATION. The plug of this cock is inverted and the pressure upon the rod in opening or closing the valve tends to loosen the plug and facili- tate its movement. The joint is kept tight by the pressure of the water from the street side, a by-pass admitting water under pressure to the under side of the plug. The stop and waste cock at the curb is usually provided with a tee handle, that in the basement, with a lever handle. A compression stop and waste cock, somewhat similar in appearance and operation to an ordinary faucet, has been recently introduced on the mar- ket, and may be used to advantage in some cases. For lead-pipe work the fittings provided with union joints are to be preferred, as their use affords a means of ready access to the interior of the pipe in case of stoppages caused by small fish, eels, or ice. The joints between the lead pipe and fittings may be made in any of the ways mentioned in the consideration of the joint between the corporation cock and the gooseneck. The fixtures in any ordinary residence or building may be adequately supplied by a service connection of five-eighths or three-quarters of an inch in diameter, but hotels, business blocks, etc., often require services of larger size. For ordinary service connections, pipes of wrought iron, which may be plain, tarred, galvanized, or lined with cement, lead, or tin, and of lead or tin-lined lead are in common use. Services larger than two inches in diameter may usually be more eco- nomically laid with cast-iron pipe. The three classes of pipe first mentioned are a source of considerable annoyance and expense in many systems, as some waters corrode the iron with great rapidity, the tar or galvanized coatings as at present applied merely postponing this action in a measure. As a result of the corrosive action the pipes are quickly filled with rust, fixtures and meters clogged, and the water rendered objectionable for laundry purposes. Cement-lined iron pipe when properly lined often gives entire satisfaction, but has been found objectionable in some cases owing to the cracking and flaking off of the cement and the diffi- culty in obtaining rust-proof joints. This pipe has been success- fully used in Brookline, Massachusetts, for more than twenty-five years, and the methods used in its lining have been described in SERVICE CONNECTIONS. 255 detail by Mr. F. F. Forbes in a paper read before the New England Water-works Association, from which the following extracts are taken:* ' ' Our departure from the usual custom begins with the buy- ing; we specify that the lengths shall be about 16 feet long and also of standard weight. A pipe 18 or 20 feet long cannot be lined with the same degree of success which can be obtained with pipes somewhat shorter; and our experience has taught us that pipes about 16 feet long give the best results. After the pipes are delivered at our shop, we first straighten all which are much bent. The couplings are then removed, turned around and screwed on the other end, in order that there may be no trouble in putting the lengths together when lined. The pipes are then carefully examined in order to make sure that no defect exists in the welds or other parts of them. The next step is to run a cutting-tool slightly smaller than the inside diameter of the pipe through each length to remove all dirt, scales, and pro- jections of iron from the welds. The pipes are now ready for lining. " No sand should be mixed with the cement. Portland cement is not fit for this work, being too heavy and liable to fall from the sides of the pipes before setting. We have used the F. O. Nor- ton brand with great success; but any good American natural cement which does not set too rapidly and is freshly ground can be used with confidence. It is very necessary to sift all the cement through a moderately fine sieve, as we find that even the best cements contain small pieces of unground rock and other substances which interfere seriously with the lining. It is also extremely important that the cement should be used quickly after wetting. When lining we have one man who does nothing but mix the cement, usually preparing enough for five or six pipes at one time and constantly working it over to keep it at the right thickness. If a little of the batch is left, we pre- fer to throw it away rather than to mix it with the next lot. The press used for filling the pipe is made by the Union Water Meter Company, of Worcester, Mass, in fact, they make the *" Cement-lined Service-pipes." F. F. Forbes, Jour. N. E. Water- works Assoc'n, Vol. XV. 256 MAINTENANCE AND OPERATION. whole outfit, including cones, etc. It is necessary to fill the pipe entirely full of cement, and a little should be allowed to run out of the farther end. More of the cement will be pushed out by the cones, but this can be returned to the mixing-box and used again, with the exception of that from the last pipe filled from the batch, which is thrown away. In every case the cones are passed through the pipes twice. A handful of cement is pushed into the pipe before the cone enters the second time, and while it is being drawn through, the pipe is slowly revolved to keep the cone in the center of the pipe. We endeavor to keep the cones as near the center of the pipe as possible; we find, however, that the practical results are the same if the lining is quite uneven. The cones are thoroughly washed after each pipe is lined; before they are drawn through, a piece of pipe from 12 to 18 inches long is screwed to each end of the pipe to be lined, so that the lining at the end will be perfect. After the pipes have been lined from three to five days, or until the cement has sufficiently set, a thin gruel of cement is run through them. This is done by elevating one end of the pipe and pour- ing the gruel in from an ordinary watering-pot. A rubber cone is now drawn through, which leaves the inside of the pipe smooth and quite impervious to water. The ends are now reamed out to fit the composition ferrules and the threads cleaned. This completes the process, and the pipes are piled away for use. The number of feet of pipe of different sizes lined and grouted by one barrel of cement is as follows: 1 -inch pipe 700 feet ij- " * 500 " 2 - " " 300 " In 1898 the cost of labor, cement, etc., for lining 3000 feet of 2-inch pipe and 9000 feet of i-inch pipe was as follows: Labor preparing pipes $65 . 79 " cementing 66 . 65 " grouting 22 . 66 " reaming 39-98 23 barrels cement @$i .10 25 .30 Coal for heating shop 6.00 $226.38 SERVICE CONNECTIONS. 257 which gives the cost of lining 2-inch pipe 3.03 cents per foot, and cost of lining i-inch pipe 1.5 cents per foot. " Two men usually get the pipe ready for lining, but during the process of lining, six men are found to be the most economical number to use, distributed as follows: one man mixing the cement, one man filling the press and overseeing the work, one man working the press, one carrying the pipes to the press and from the press to the coning-frames, and two men, one at each end of the pipe, doing the coning. In one day these men will line from four to five thousand feet of pipe. "A few words describing the ferrules we use at all joints. These are made of the best steam metal, five-eighths of an inch in diam- eter on the inside, the outside tapering slightly toward the end. They are of two kinds, called by us a double and a single ferrule. The double ferrules are used where the pipes are screwed together, and the single ferrules where the pipes are screwed into the side- walk stops and connections at the main, which are made with a shoulder at the end of the thread to hold the ferrules in place. " It has often been stated that the cement-lined pipe cannot be bent without injury. We find, however, that the pipes can be bent to any reasonable extent, without any damage to the lining, if this is done with care. We rarely use any elbows or tees. If we have to use a turn smaller than we think best to bend the pipe around, we use a short piece of lead pipe, perhaps a foot long, with a coupling on the end, and in making the connection use ferrules." Tin-lined pipe is not extensively used owing to its cost, but when of good quality it possesses an advantage over other service- pipes, inasmuch as tin is rarely affected by potable waters. The numerous reported cases of lead-poisoning resulting from the use of water drawn from lead service- pipes have prejudiced some consumers against them, and have caused water- works officials and others to doubt the advisability of the use of pipes of this material. Under certain conditions such use may endanger the health of a community, and it would be advisable to enlist the services of a chemist conversant with this matter before the adoption of lead as the material for the service-pipes of a system. Investigations of the action of water upon lead pipe have been made in Massachusetts under the direction of the State Board of 258 MAINTENANCE AND OPERATION. Health, the results of which appear in the published reports of that board. The results of these investigations indicate that the corrosive action of the potable waters of Massachusetts upon lead is due principally to the presence in the water of comparatively large amounts of carbonic acid, and, in a measure, oxygen; the extent to which the dissolving action takes place being dependent chiefly upon the degree of hardness of the water. ' ' The greater the hardness of the water, as compared with its free carbonic acid, the less effect did the carbonic acid have upon lead." * The following extracts from the published reports are of interest in this connection. "Nearly all of the serious cases of lead-poisoning resulting from the use of water taken from public water-supplies (in Mas- sachusetts ) have occurred in those cities and towns which are sup- plied with ground-water; but surface-waters also act upon lead pipe, and though the quantity found in surface-waters drawn through such pipes has usually been small, there is, nevertheless, danger that injury to health may result even if the water is drawn from a surface source if lead pipe is used in its distribution." f "A water which ordinarily acts but slightly on a lead pipe may, by some change in conditions, take up a much larger quantity of lead than under ordinary circumstances, and a change in the source of the supply of a city or town has been followed by a material increase in the action of the water upon lead service-pipes." { "While the quantity of lead dissolved may be small, and a single dose might not seriously harm the user of the water, the continued use of water containing lead is harmful, because lead is a cumulative poison. The exact amount of lead which may be taken into the system without producing harm is not definitely known and may vary with different people, but it is known that the continuous use of water containing quantities of lead as small as .05 of a part per 100,000, or about ^ of a grain per gallon, has caused serious injury to health." However, since many potable waters do not attack lead seriously, and in the case of some soft surface-waters, the presence in the * Report of Mass. State Board of Health, 1900, p. 488. t Ibid., 1 901, p. xxxi. % Ibid., 1901, p. xxxii. Ibid., 1898, p. xxxii. SERVICE CONNECTIONS. 259 water of certain mineral matters results in the formation of coatings on the interior of the pipe which serve to protect the metal, pipes of lead, or of iron lined with lead, are frequently used. As a measure of precaution in any case where lead or lead-lined pipes are in use, the water which has stood in the pipes overnight or for any con- siderable length of time should be wasted. The quantity of water contained in service-pipes may be com- puted with the aid of the following table. Internal diam. of pipe in ins. if f i il i| 2 Contents in gallons per 100 feet of pipe 1.02 1.59 2.30 4.08 6.38 9.18 16.32 The service-boxes in general use are of the telescopic pattern and usually consist of three parts: a base or lower section, an upper section, and a cover. The lower section is enlarged at the bottom in order that the curb-cock may be partially enclosed and also that resistance may be offered to the lifting action of frost. The upper section either slides over the lower or is connected to it by a threaded joint. One objection to the threaded joint is, that in some soils the entire box is lifted by frost action and can- not easily be driven back into place; another is that the upper section of a box of this kind is more liable to be damaged by teams. Circular covers are commonly used, but boxes set in brick walks should be provided with square or rectangular covers. The top of the box or cover should have a beveled edge, as this offers less obstruction to passers-by. The cover is held securely in place by a brass screw-bolt provided with a triangular or pentagonal head, as loose covers or covers held in place by bolts with square or hexagonal heads are easily removed by small boys and other unauthorized persons. This bolt either screws into the top section of the box or forms a part of a special clamp designed to hold the cover in place. In several designs for service-boxes another casting is added, the purpose of which is to hold the stop-cock in the center of the box with the tee head in a vertical position. Some boxes are provided with a short rod which is attached to the cock and held in the center of the box by lugs on the interior of the casing. Boxes of this type may be used occasionally to advantage in localities where the ground-water rises in a soft 260 MAINTENANCE AND OPERATION. material, with the result that the bottom of the box is often partly filled with mud. A disadvantage of the type is that it permits of too easy access to the shut-off by unauthorized persons. As a general rule, the service connection should be laid at Buffalo. Stacy. FIG. 70. Service-boxes. Chadbourne. right angles with the street-line and below the depth ordinarily reached by frost. It should enter the basement of the building to be supplied about one foot below the level of the floor, as this location affords better opportunities for the protection of the pipe, SERVICE CONNECTIONS. 261 stop and waste cock, and meter, if meters are used, from freezing. Where pipes are brought through the foundation walls above the level of the basement floor, freezing is liable to occur on the street side of the stop and waste cock when the water is shut off at night in houses not provided with heat in the basement, and in others when the building is unoccupied temporarily, and the water not shut off at the curb. When lead pipe is used a small arched opening should be left in the wall as a precaution against injury to the pipe caused by settlement or sliding of the wall stones. The location of the consumer's stop and waste cock should be such that it is accessible at all times, and in no case should the shut-off be placed in coal-bins, ash-pits, or in places where it may be covered with wood or rubbish. The stop and waste cock at the curb should never be omitted, as it will be found useful in the enforcement of regulations regard- ing non-payment of rates, and for cutting off the supply from premises which are vacant. On paved streets the cock should be so placed that the service-box will be in the sidewalk next to the curbstone, and in suburban streets, so that the box will be located in the grass ground between the gutter and the walk, as a precaution against accidents resulting from persons tripping over the box or cover. The water should be turned on and all joints tested under pressure before the trench is refilled, as the water escaping from an imperfect joint will, especially in sandy soil, with the aid of particles of earth, rapidly cut away the pipe or fitting. Many persons object to the use of one trench for both water and sewer connections on the ground that leakage from the service con- nection may enter the sewer undetected. However, a leak of sufficient size to be detected by the appearance of water on the surface of the street where escape into a sewer is impossible will, if such escape is possible, usually make its presence known to a water-taker by a disagreeable roaring or hissing sound from the interior piping. Nevertheless, in cases where service-pipes have previously been laid, it is advisable to make a separate trench for the sewer connection as a precaution against injury to the service due to settlement, particularly when the sewers are laid by contractors or individuals. 262 MAINTENANCE AND OPERATION. The prices of materials required for service connections depend upon the quantity purchased, its quality, and the discounts from list prices in force at the time purchases are made. Tapping-machines including drills and taps for ordinary ser- vice work cost from $60.00 to $125.00. Corporation and stop and waste cocks when purchased in small quantities cost about as follows: Style. Size. t" 1" i" Corporation cocks with coup- lings $ O . "? 5 tO O.8^ $ o . 80 to 1.05 $ I . 2O to I .60 Ordinary round-way stop and wastes for iron pipe o . 1 1 to o . 8 i 0.85 to i . 2 1 Inverted key stop and wastes for iron pipe i . -} c 2.21 Compression stop and wastes for iron pipe i . 40 1.71 Ordinary round-way stop and wastes for lead pipe o . 60 to 0.75 o . 80 to o. 90 I . OO to I . 1O Ditto with union joint O 71 to O OO i oo to i 10 i 25 to i 7 1 Inverted key stop and wastes for lead pipe I 11 i 3 1 2 21 Lead flange stop and wastes for lead pipe . . . I . 11 i .80 2 OO Inverted key with lead flange connections. I . ncr 2 . 2O 7 t?O Compression stop and wastes for lead pipe i . oo to 1.15 Service-boxes cost from 65 cents to $1.80. COST OF GALVANIZED-IRON SERVICE-PIPE. Size, inches f i ij i 2 List price per foot $o.n $0.16$ $0.22^ $0.27 $0.36 (0.04 0.06 0.07^ 0.09 0.12 to to to to to 0.05 0.07^ 0.09 o.n 0.15 COST OF LEAD- AND TIN-LINED IRON SERVICE-PIPE. Size, inches f i Lead-lined, per foot $0.14 $0.21 Tin-lined, per foot o . 24 0.32 The cost of cement-lined iron pipe is about as follows when made by the department. This pipe cannot be purchased at present from dealers in service supplies. SERVICE CONNECTIONS. 263 Size. I inch lined to f inch " " 4i " Approximate cost per foot. $o .09 o 12 0,15 2 " " " if " .................... 0.18 Lead pipe costs from 5 to 5J cents per pound. The weight per foot of lead pipe is governed in a measure by the pressure to which the pipe is subjected, and also by the 200 150 100 90 / t 1 f t / / / i -- , / T 7 g ' I 80 70 60 50 s, 40 F *0 / ,/ / t / / / i \ i ] i i / r 1 - t -- :::::::jf ::5i| / / ?/ i i tE~ / / rn _ _ (_ s 2j 2 / v , ptJ / x ->. / ^ 2 / / -v 2 ./ / / / s- c / / V / c. 2 / / c y > h ir, / / / ^/ i' / C 9 / / / / ^ / / t r ^ 7 a J / / / / ( v j / / /~ / S v2 j / / / / ^ ? S! / J / / / / 1 y f / f / / / / i / / / / V J / / / J f t / ]_ . I } 4 1 " i 1 . 30 40 00 00 70 80 sKUOO 150 2U Flow in Gallons per Minute FIG. 71. Discharge of Service-pipes. standard weights supplied by the manufacturers. The weights given in the following table are sufficient for ordinary water- works purposes. The light pipe may be used on gravity works under a low head, the heavy for general purposes. WEIGHTS OF LEAD PIPE PER FOOT. Internal diameter, inches \ f i i$ Light, pounds 2 i\ 3 4 6 Heavy, pounds 3 3$ 4i 6 9 264 MAINTENANCE AND OPERATION. Solder costs from 20 to 25 cents per pound. The following quantities are usually allowed for "wiped" joints. Diameter of pipe, inches J f f i i^ Pounds of solder f i i i i if Very little solder is required for " cup " joints. Tin-lined lead pipe costs from gj to 10 cents per pound. The cost of the labor required for excavating, back-filling, and pipe-laying, including the tapping of the main, averages from 10 to 25 cents per foot. It is seldom necessary to make any computations of the dis- charge of service-pipes, since an ample supply is usually furnished through any of the sizes of pipe ordinarily connected to a sys- tem. Such computations are sometimes made when buildings are located at a distance from the street-mains and at an ele- vation where the pressure is low. Fig. 71 has been prepared from the figures given in Weston's Tables, and may be used for long lines of pipe having a very smooth interior surface similar to lead. CHAPTER IV. METERS. THE meters in general use for measuring the water furnished consumers are of the positive type. Meters of this type measure and automatically record, with varying degrees of accuracy, the amount of water which has passed through them, and are divided into several classes, known as reciprocating, rotary, oscillating, and disc piston meters, depending upon the type and mode of operation of the piston which is displaced by the passage of the water. Meters of the first class are provided with pistons or plungers which operate in a manner somewhat similar to those of a reciprocating pump. Those of the second class are pro- vided with either two pistons of irregular form which revolve about fixed centers within an oval chamber, much like the runners in a rotary pump, or a single-toothed piston, which moves in a cylindrical chamber, the interior surface of which is provided with a number of projections and indentations. In the latter case the piston does not rotate about a fixed center as in the previous instance, but moves in such manner that the projections on and recesses in the piston and walls of the casing form a series of measuring-chambers. In meters of the fourth class mentioned the piston has a disc form and moves with an oscillating or wab- bling motion, in its movement dividing the chamber alternately into receiving- and discharging-spaces. A radial slot cut in the disc embraces a fixed plate or wedge set vertically within the chamber and which prevents rotation of the disc. The oscillating piston meters operate in a somewhat similar manner. For ordinary purposes the pistons or discs are made of hard rubber, which in some makes is reinforced with metal. Each complete revolution of the piston or disc permits the passage 265 266 MAINTENANCE AND OPERATION. through the meter of a quantity of water equal to the contents of a chamber or series of chambers of known capacity. A spindle attached to the piston or disc engages a train of gearing by which the movement of the piston or disc is transmitted to a dial or series of dials. The quantity of water which has passed through the meter is thus registered upon the dials in either cubic feet or gallons. The smaller meters are usually provided with strainers located FIG. 72. f-inch Union Rotary Piston Meter. within the base and forming a part of the meter. Similar strainers are placed in some of the larger meters, but in general an addi- tional fitting known as a fish-trap is set in connection with the meters of large size. Where the water carries considerable grit in suspension, or if small fish are often present in the pipes, the use of an independent fish-trap or grit-chamber is often advisable with the smaller meters, since the former appliances are more readily cleaned. The type of meter to be used in any particular case depends to a considerable extent upon local conditions: the size of ser- METERS. 267 vice, amount of water consumed, pressure, the presence of sand, or other sediment in the water which would cause excessive wear of the casing and moving parts, the accuracy of registration desired, etc. In the selection of a meter the following points should be given consideration: 1. Accuracy. 2. Sensibility. 3. Durability. 4. Obstruction to flow. 5. Accessibility of working parts. 6. Liability of stoppage. 7. Cost of repairs. 8. Extent of damage as a result of freezing. 9. Capacity. 10. Cost. Service-meters of the usual size, five-eighths to three-quarters of an inch, when new should not over-register more than one per cent, and on varying rates of flow should register approximately the following percentages of the quantities of water actually passed through them: Flow in cubic feet per hour. Per cent registered. 0.5 50 i .o 90 6.0 97 15.0 to maximum capacity 98-99 The maximum capacity of service-meters is given by the different manufacturers as follows: Cubic feet. Gallons. Size inches. Per minute. Per hour. Per minute. Per hour. I 2 120 15 900 I 4 240 30 1800 I 480 60 3600 Where the detection and prevention of waste are of importance, meters should be tested for their sensibility to STiall rates of flow. This factor may be determined by testing a meter under a flow just sufficient to cause registration and noting the quantity passed and the percentage registered in a given time. In many cases this sensibility decreases to a large extent with use and tests 268 MAINTENANCE AND OPERATION. n> s? METERS. 269 of this nature are of more value when made in connection with the durability test. The test for durability is made by passing through the meter a quantity of water equivalent to the consump- tion of an average family during five or ten years, approximately 100,000 cubic feet, after which the meter is tested for accuracy and sensibility. This test is usually made only in the comparison of meters of various types or makes as a guide to the selection of the type or make of meter best adapted for use on the works. FIG. 74. Section of Worthington Disc Meter. The obstruction to the flow of water through a service con- nection due to the introduction of a meter is at times of impor- tance, since it may be necessary in a given instance to use a meter of larger size than would be the case if a type or make of meter causing a less loss of head was selected. This consideration is of particular importance where meters are placed in pipes which supply water to motors or for purposes of fire-protection. The published results of tests made by Mr. J. W. Hill, C. E.,* of twelve five-eighths-inch meters and one three-quarter-inch meter of differ- ent makes, and by Mr. J. Waldo Smith, C. E.,f of six five-eighths- * Trans. Am. Soc. C. E., Vol. XLI, p. 407. ^ Ibid., p. 377. 270 MAINTENANCE AND OPERATION. inch meters, indicate that the loss of head caused by meters of the size tested is about as follows: Flow in cubic feet Loss of head in pounds per square inch. per minute. Tests by J. W. Hill. Tests by J. W. Smith. 20 13 to 30 8 to 33 1.5 7 to 17 5toi8 i -o 4 to 13 2 to 8 0.5 2 to 4 i to 3 The meters included in the above table were all of the posi- tive displacement type. As a general rule, the size of meter to be used in a given instance should be based upon the amount of water used,- and the rate of Cylinder, with piston. Base. FIG. 75. Cylinder, Piston, and Base of AA Empire Meter. flow, rather than upon the size of the service connection in which the meter is to be placed. A f-inch meter will usually prove satisfactory for domestic service. For this purpose meters of the disc type are commonly used in preference to those of the piston pattern. Aside from the durability, permanence of regis- tration, and economy in first cost and maintenance of disc meters, meters of this type possess a peculiar advantage over other types as a leak-detector. Mr. Hill * found that a noticeable vibration of the discs and attached spindle in the meters of this pattern tested occurred with rates of flow due to small leaks in the ser- * Trans. Am. Sec. C. E , Vol. XLI, p. 350. METERS 271 vice-pipe and fittings which were not sufficient to cause regis- tration. The following prices are given in the manufacturers' lists: Disc . $8.00 ;ttern. t. Size of meter. | inch f " 12 . oo i " 16 . oo 1 J inches 30 . oo 2 " 50.00 Piston pattern. Cost. $IO. OO tO $12 .OO 15 .OO " 21 .OO 2O.OO " 30.00 40 . oo " 50 . oo 60.0O " 65.00 A considerable reduction from the above prices may usually be obtained when large numbers of meters are purchased. Round reading register. Straight reading register. FIG. 76. Meter-dials. Meters should be tested for accuracy before being placed in service, and, where meters are used to a large extent, suitable testing apparatus should be provided for this purpose. An inde- pendent supply-pipe should be laid from the street-main to the testing-room, a bench, connecting pipes, and fittings, pressure- gages, discharge-orifices from -fa to i inch diameter, and a measur- ing-tank provided. This tank may be calibrated and provided with a glass-tube gage with a scale indicating the contents of the tank corresponding to the height of the water in the tube; or the tank may be placed upon a platform scale, the water weighed, and the contents of the tank in cubic feet or gallons computed or read from tables prepared for that purpose. This latter method of testing is that generally adopted. 272 MAINTENANCE AND OPERATION. The meter-testing apparatus of the Concord, N. H., water- works is shown by the accompanying illustration. The Bureau of Standards at Washington has recently installed a meter-test- ing apparatus consisting of a bench, a Gow meter-clamping device, meter support, multiple-delivery cock with twelve orifices from -g^-inch to 2 inches in diameter, a tank of 64 cubic feet capacity, and a 5ooo-pound Fairbanks scale. The cost of the equipment was about $350.00. The Gow clamping device and the various patterns of multiple- delivery cocks are almost indispensable in cases where large num- FIG. 77. Meter-testing Apparatus, Concord, N. H., Water-works. bers of meters are tested, owing to the saving in time effected by their use. Where but few meters are tested, short lengths of rubber hose fitted with suitable couplings may be used to connect the meter with the piping. The rate of flow may be varied by orifices drilled in brass screw-plugs, or in brass caps which are placed on the end of the outlet-pipe, or thin brass plates may be drilled and set in unions or couplings. A tight cask may also be used in place of a special tank. The orifices for the regulation of the discharge should be placed on the outlet side of the meter, and the water should be discharged into the measuring-tank at an elevation somewhat higher than the meter. The use of an independent supply-pipe for the meter-testing apparatus insures a more uniform pressure during tests. METERS. 273 Before starting a meter test, water should be allowed to pass through the meter for a short time or until the air in the meter is expelled and the moving parts work freely. Care should be taken to turn the water on slowly, otherwise the disc or registering mechanism may be injured. The meter should be stopped when the indicator of the one- cubic-foot dial is at the zero-point, the scale balanced, and the weight recorded. The flow is then started, time noted, and 5 to 10 cubic feet passed at the maximum rate. During the test the readings of the pressure-gages on the inlet and outlet sides of the meter are observed and the loss of head recorded. The flow should be stopped when the indicator of the one-cubic-foot dial is at the zero-point, time noted, quantity passed noted, and weight observed. The method of procedure is similar at the smaller rates of flow except that a smaller quantity of water is passed through the meter. During tests with the smallest orifices the meter should be examined for leakage. For convenience, tables should be prepared which show the quantity of water in cubic feet corresponding to the weight of water found in the tank. The weight of a cubic foot of water varies with its temperature, but for ordinary work the weight is taken as 62.5 Ibs. In some works the tables are based on the weight at 70 F. or 62.3 Ibs. WEIGHT OF ONE CUBIC FOOT OF WATER. Temperature. Weight, degrees Fahrenheit. pounds. 40 62.42 45 62.42 50 62.41 55 62.39 60 62.37 65 62.34 70 62.30 75 62.26 The accuracy of the meter, or the percentage of the actual amount of water passed which is registered on the dials, is obtained b)' the following formula: /Quantity indicated by meter\ Percentage registered = 100 ( ^ -r- : -. ) . V Quantity in tank / 274 MAINTENANCE AND OPERATION. Data with regard to the meters tested, the details of the tests made, and the results obtained should be preserved in books or on cards for reference. In setting a meter, care should be taken that the meter is secured firmly in place and that it is level. Red or white lead should not be used in making joints, and the service-pipe should be flushed before the meter is connected. If there is a liability "toi **-?/. &.&./.. ..... .... RESULT OF TEST WHEN NEW. Registered Actuel Flow .4/7 erp /Q SL FACE. REVERSE SIDE. FIG. 78. Card for Meter Tests, Baltimore Water Department. (Eng. News, vol. XLVIII, p. 357.) that hot water may reach the meter from the interior piping, a check-valve should be provided near the outlet. Meters are placed in basements, manholes, or boxes, the loca- tion and method of protection being dependent upon local con- ditions. The meter should always be placed on the house side of the curb stop and waste cock, and valves should be placed on each side of large meters in order that they may be accessible for inspection or repair. Meters placed in basements are enclosed in boxes of wood or brick, which are filled with sawdust, mineral wool, or other suitable material if any possibility of freezing exists. Meters METERS. 2 75 placed outside buildings ate set in manholes or boxes. Large meters should be enclosed in masonry vaults or manholes in order that the meter, fish-trap, and controlling-valves may be accessible without digging. Service-meters are placed in large boxes of wood provided with iron covers, one or more lengths of sewer-pipe, or a light cast-iron box, the meter being set near the surface in order that the dials may be easily read, with ver- tical inlet- and outlet-pipes enclosed within the box; or the meters are provided with dial extensions and are set at the same grade as the service connections, the meter and dial extension being FIG. 79. Manhole Setting for Large Meters. FIG. 80. Volkhardt Meter -box. enclosed in a small iron box somewhat similar to a street or serv- ice-valve box. The use of dial extensions is objectionable, as the friction of the registering mechanism is increased and the sensi- bility of the meter often seriously impaired by the addition of a dial extension. Large numbers of service-meters have been set during recent years by the city of Cleveland in sewer-pipe, the method of setting at present in use being shown in Fig. 81. The meter is protected from frost by a tight cover of wood treated with preservative chemicals, which is placed below the outside iron cover to pre- vent the circulation of air about the meter. This wood cover consists of a circular rim, which is calked in place with oakum, and a small cover which is opened when the meter is read. An extra foot of sewer-pipe is used where the danger of freezing requires additional precaution. The experience with meters 276 MAINTENANCE AND OPERATION. set in this manner during the unusually severe winters of 1903 and 1904 has been very satisfactory. SECTION A-B Standard C.I. Manhole and Cover 14&- Calked with Oakum - h if- ii f -H---J i a L _i Cj J'.vi. FIG. 81. Setting for Water-meters, Cleveland, Ohio. The cost of setting service-meters in basements is found by different water departments to be about as follows: Taunton, Mass $2 . 50 Watertown, " i . oo Brookline, c ' 2 . oo Springfield, " 1.50 to 2.00 Fitchburg, " i . 25 Lawrence, ' c i . 25 Wellesley, " i.oo The cost of setting f-inch service-meters in Cleveland, Ohio, during 1903 is given in the following table: * * "The Meter System in Cleveland." Am. Water-works Assoc'n, 1904. Edward W. Bemis, Proceedings of METERS. 277 Basement settings. Brick vaults. Sewer-pipe settings. Brick. . .... $O . I 2 350 brick $2.45 Sewer-pipe $i . 46 Cement . . O O c; Cement o. 38 Frost-cover o . 1 8 Cover O 3O Iron ring and Iron ring and Fittings. . . . O 2 Z cover 7.21 Fittings o. ;o Pipe and fittings 0.55 &0 72 Labor .... 90 . 7 2 32 3 Material $6. 49 T 12,475,270 16.7 1 Includes water used for public purposes. CONSUMPTION OP WATER THROUGH METERS IN BELMONT, MALDEN, MILTON, AND WATERTOWN, MASS.* City or town. Number of consumers. Gallons per day. Gallons per day per consumer. 1901. 1902. 1901. 1902. 1901. 1902. Belmont. . 3,600 2I.IOO 6,850 9,650 3.900 22,550 7.450 10,250 63,760 414,030 115,000 147,200 66,630 450,160 143.500 152,900 17.7 19.6 16.8 *5-3 17.1 20. o s 9-3 14-8 Maiden Milton Watertown 41,200 44,150 739,990 813,190 18.0 18.4 " In the towns of Belmont and Milton every service-pipe is metered, in Watertown 89.5 per cent, and in Maiden 63.4 per cent. The above quantities include water used for stables supplied in connection with dwellings and that used for lawn- sprinkling, as well as that used strictly for household purposes. In all these municipalities the meters have been in use but a comparatively few years, and it is not probable that they have become worn so as to cause a large percentage of error in regis- tration." * *" Report on the Measurement, Consumption, and Waste of Water Supplied to the Metropolitan Water District." Dexter Brackett, C.E., Jour. N. E. Water-works Assoc'n, Vol. XVIII. WATER WASTE. 327 USE OF WATER IN TENEMENT-HOUSES IN BOSTON DURING 1902.* Ward. Number of houses. Number of families. Number of persons. Gallons per day. Monthly rental. Per family. Per capita. Ward 6. . 21 8 13 15 2O 12 10 21 20 IO IO 9 263 75 155 I 3 I iji 116 88 209 250 in 89 81 1226 365 755 625 758 553 420 949 "35 545 437 398 H5 7 1 64 U3 92 141 138 15 20O I9O 194 218 24.8 14-5 13-2 23-7 20.7 29.6 29.0 33-i 43-9 38.7 39-5 44.4 $12 to $16 12 to 16 16 to 20 16 to 20 12 to 20 20 tO 25 25 to 30 25 to 30 30 to 40 25 to 45 35 to 55 50 upwards Ward 7 Ward 7 Ward 8 Ward 9 Ward 8 . . Ward 8 . Ward 10 Ward 10 \V T ard ii Ward ii Ward ii 169 1739 8166 139 29.63 DOMESTIC CONSUMPTION PER CAPITA IN NEWTON, FALL RIVER, WORCESTER, AND LONDON, ENG.., AS DETERMINED BY METER MEASUREMENT.* City or town. Number of houses. Number of families. Number of persons. Con sumption. Gallons. Remarks. Per family. Per capita. Newton 49 49 2450 132.5 26.5 All houses supplied with mod- ern plumbing Newton. .... 619 35 6.6 These families have but one faucet each Newton ___ 278 I 3QO "I A C 6 o These families have but one m ' x oy J*T ' J \j . y faucet each Fall River. . . 28 34 170 "7.5 25-5 The most expensive houses in the city Fall River. . . 64 148 740 42.0 8.4 Average class of houses, gen- erally having bath and water-closet Worcester. . . 81 327 80.2 19.9 Woodland Street, best class of houses Worcester. . . 37 187 H8.I 23-4 Cedar Street, best class of houses Worcester. . . 93 447 95-o 19.8 Elm Street, houses of moder- ate cost Worcester. . . 245 1104 55-1 12.2 Southbridge Street, cheaper houses Worcester. . . 229 809 55-o 15-6 Austin Street, cheaper houses London, Eng. 1169 8183 25-5 Houses renting from $250 to $600; each have bath and two water-closets London, Eng. 727 5089 18.6 Middle class, average rental, $200 *" Report on the Measurement, Consumption, and Waste of Water Supplied to the Metropolitan Water District." Dexter Brackett, C.E., Jour. N. E. Water-works Assoc'n, Vol. XVIII. 328 MAINTENANCE AND OPERATION. In localities where water is paid for at meter rates and a minimum rate established, the records of the consumption in cases where a less quantity of water is used than the consumer is entitled to under the minimum charge furnish data with regard to the actual requirements for domestic purposes. In 1888 an analysis of the accounts of consumers in the city of Provi- dence who paid only the minimum rate this minimum being $10.00 per year, for which amount the use of 91.32 gallons per day was permitted showed the following results: * Peranmun. 167 families drew less than 1500 cu. ft. 337 families drew the previous amount but less than 2000 cu. ft. 361 families drew the previous amount but less than 25 cu. ft. 445 families drew the previous amount but less than 3000 cu. ft. 446 families drew the previous amount but less than 3500 cu. ft. 462 families drew the previous amount but less than 4000 cu. ft. 435 families drew the previous amount but less than 4457 cu. ft. :r Which, at 5 day per tap. persons per family, = 30.742 = 6.15 gals, per capita =- 40 . 989 = 8 . 20 gals, per capita =* 51.236 =- 10. 25 gals, per capita = 61.484 = 1 2 . 30 gals, per capita =- 71.731 14-35 gals, per capita = 81.978 16.40 gals, per capita 91.324 = 18.27 gals, per capita A similar analysis of accounts of the year 1901 in the city of Maiden, Mass. where the minimum rate is $12.00, for which amount the use of 130 gallons per day is permitted showed the following results: | ~K (-, au . CJ ssl Distance in feet between points of contact on pipe. ftj ^1 i 2 3 4 5 6 7 8 9 IO "2 c Ilia c ; Current on pipe per millivolt drop. 4 20 13-9 6. 9 4.6 3-5 2.8 2-3 2 .0 7 i-5 1.4 6 3 20.8 IO.4 6.9 5-2 4.2 3-5 3-o 2.*6 2-3 2 . I 8 39 27.1 13-5 9.0 6.8 5-4 4-5 3-9 3-4 3- 2.7 10 58 40.3 2O. I 13-4 IO. I 8.1 6.7 5-8 5- 4-5 4.0 12 84 58.3 29.1 19.4 14.6 12.0 9-7 8-3 7-3 6-5 5-8 16 I2O 83-3 42 .O 28.0 21 .O 17.0 14.0 12.0 IO.O 9-3 8-3 20 180 125.0 63.0 42 .0 31.0 25.0 21.0 18.0 16.0. 14.0 12.5 24 220 153-0 76.O 51.0 38.0 31.0 25-5 22 .0 19.0 17.0 15.0 30 310 216.0 108.0 72.0 54-0 43-o 36.0 31.0 27.0 24.0 22.0 36 440 306.0 I 53- IO2 .0 76.0 61 .0 51.0 44.0 38.0 34-o 32.0 42 560 389.0 195.0 130.0 97.0 78.0 65.0 56.0 49-o 43- 39- 4 8 720 500.0 250.0 167.0 125.0 IOO.O 83.0 71.0 62 .0 56. c 50.0 60 90O 624.0 312 .0 2O8.O 156.0 125.0 104.0 89.0 78.0 69.0 62 .0 *" Surveys for Electrolysis and their Results." D. H. Maury, Proc. Am. Water-works Assoc'n, 1903. When the above table is used, care should be taken that pipe bells or joints are not included between the points of con- tact of the leads from the instrument. The following method for the approximate determination of the flow of current is given in Herrick's Electric Railway Hand- book. Wires from a voltmeter and an ampere-meter are inde- 350 MAINTENANCE AND OPERATION. pendently connected with points on the water-main. Readings of the voltmeter are taken with the circuit through the ampere- meter open, and also with this circuit closed. At the time the latter voltmeter readings are taken the ampere-meter is also read. Then X:A::V l :V 1 -V 2 or X=* V \ 7 , I/I- 1/2 where X = normal current flow on pipe, A = current diverted through the ampere-meter circuit, FI = voltmeter reading with ampere-meter circuit open, F 2 = " " " " " closed. If the connections of the hydrants to the mains are electrically good, approximate results may be obtained by this method by connecting the leads from the instruments with adjacent hydrants on the same main. Owing to the uncertainty with regard to these connections, however, the experiments should be made on several sets of hydrants, or upon a comparatively short length of pipe exposed in an excavation. In all tests the surface of the pipe should be brightened with a file and care taken to secure good electrical connections between the instrument leads and the pipe. The primary investigations are preferably made under the direction of an experienced engineer, but subsequent periodical examinations may be made by em- ploye's of the department provided with suitable instruments for that purpose. Conditions favorable to electrolytic action as regards water- pipes are not found when the re turn- current of a street-railway system is completely removed from the ground. The practicable method by which this removal may be effected is the adoption by the street-railway companies of the double- trolley system. This method is not regarded with favor by the railway corporations, since new problems of construction and maintenance and con- siderable financial outlay are involved in a change from existing conditions. Although the injury to water-pipes and appurte- nances resulting from the operation of electric railways by the single- trolley system is now an established fact, such legal actions as have been instituted for the purpose of compelling electric- railway corporations to change from the single- to the double- trolley system have not as yet accomplished the end sought. ELECTROLYSIS. 351 The flow of the current from the rails to the water-pipes where single- trolley systems are in use may be reduced by the adoption of better methods of track construction, such as drainage of the sub-grade, the use of heavier rails, and improved methods of bonding, and the installation of overhead return-circuits con- nected to the rails at frequent intervals. Rail bonds often work loose and as a result the efficiency of the track return is greatly impaired. The electrical condition of the pipe system should, therefore, be examined at intervals by the methods mentioned. It is often assumed that serious damage will not occur if the readings obtained in voltmeter tests do not exceed one volt, but even in these instances considerable injury may result in the course of time, particularly if the soil surrounding the pipes is moist and impregnated with mineral salts, and the pipes are com- posed of metal which contains many impurities. Care should be taken in the location of new mains to place the pipes, valve-boxes, and hydrants as far as possible from the rails. On the other hand, when tracks are laid in streets which contain water-pipes, the rails should be placed at a distance from the pipes. The location of tracks directly over and parallel to water-mains should be avoided if possible. Cast-iron water-pipes may also be advantageously laid with the bells toward the direction in which the current will flow, as the wasting effect due to elec- trolytic action will then be confined to the heavier and larger bell ends instead of the spigot ends of the pipes. Several methods have been suggested by various writers for the protection of service-pipes which pass beneath railway tracks, such as enclosing the service-pipe in asphalt, placing the pipe in a rubber hose, or wrapping it with tape or other insulating mate- rials. When main or service- valve boxes are in close proximity to the rails, a portion of the box may be replaced with vitrified pipe. Where the flow of current is from branching mains to a large supply or distribution main, insulating joints have been made in the branch connection as a means of partially protecting the larger and more important pipes. These joints consist of two special castings which are separated by a heavy rubber gasket. CHAPTER X. FIRE PROTECTION. THE capacity of a system of water-works, particularly that of the smaller distribution mains, is usually determined in large measure by the requirements for adequate protection against fire. When works are first constructed, the amount of water supplied for domestic and manufacturing purposes is usually but a com- paratively small proportion of the total capacity of the system; but as the business of the department increases, this amount like- wise increases, and the quantity of water under suitable pressure for the purpose of extinguishing fire becomes less. The character of the service may, also, change as the commercial districts expand, so that although the provision for fire protection was satisfactory at the outset, the increased demands for domestic and manufac- turing purposes, together with the additional requirements for fire protection in the commercial and the thickly settled districts, result in rates of draft which reduce the available pressures below "the points at which satisfactory service can be given in emergencies. A diminution of the efficiency of the works in case of fire should be guarded against by measures taken to restore or maintain this efficiency, provided the financial condition of the works admits of the necessary expenditures for that purpose. Much may be done by the installation of additional hydrants, the reinforce- ment of the system by the laying of circuit lines, and the re- newal of some of the older and smaller distribution mains with pipe of larger diameter. When the pressure is inadequate after measures have been taken to improve the hydrant service, de- pendence is usually placed upon steam fire-engines when large conflagrations occur. 352 F1AE PROTECTION. 353 "^^ The efficiency of an existing system ol WOIKS as a means of protection against fire may be measured approximately by cer- tain general rules or standards. This efficiency is also at times indicated, often to the surprise of persons who have based their ideas with regard to the capacity of the works upon static hy- drant pressures, when large demands are made upon the works in the case of a serious fire. The proper allowance for a good fire stream is placed by different authorities at from 175 to 250 gallons per minute. That suggested by Mr. John R. Freeman, C.E., is a stream of 250 gal- lons per minute, delivered through a ij-inch smooth nozzle, with a pressure at the base of the nozzle of about 45 pounds per square inch.* With this pressure a i-inch smooth nozzle will deliver about 200 gallons per minute, a J-inch smooth nozzle about 150 gallons, and a f-inch smooth nozzle about no gallons. A stream of from 150 to 200 gallons per minute will usually prove satisfactory where fires occur in residential districts, the smaller quantity probably being satisfactory where buildings are so situ- ated that a fire in one does not greatly endanger adjacent property. The number of good fire streams which should be furnished simultaneously from a system is dependent upon the conditions which obtain in a given instance more than upon the population or valuation. The liability of considerable loss from fire is greater and the need of protection more if in the compact parts of the city or town the buildings are largely of wood. The width of streets, the character of the industries, the nature of the equip- ment of the fire department, whether or not steam fire-engines are available, and the presence or absence of streams from which such engines may derive their supply are factors to be taken into account in the consideration of this question. Information upon this subject given by previous experience in the handling of large fires in the municipality is also of value. The number of fire streams of 250 gallons per minute each, based upon the population of the protected community, which * John R. Freeman, "The Arrangement of Hydrants and Water-pipes for the Protection of a City against Fire," Jour. N. E. Water-works Assoc'n, Vol. VII. 354 MAINTENANCE AND OPERATION. should be available simultaneously is considered by Mr. Freeman to be as follows:* Population. Number of streams. 1,000 2 to 3 5,000 4 " 8 10,000 6 " 12 20,000 8 " 15 40,000 12 " 18 60,000 15 " 22 100,000 20 " 30 The following recommendations are made by the same authority: "So far as a general statement may apply, . . . the pipes should be large enough and the hydrants numerous enough so that two-thirds of the above number of streams could be con- centrated upon any one square in the compact, valuable part of the city or upon any one extremely large building of special hazard. Better than by data based on population, the ques- tion of the numbei of streams which it should be possible to con- centrate at any one point, as well as the question of the total number of fire streams to be provided for the city, can be best solved Dy a tour around the given city, studying out the spots where a large number of streams would be needed to check a conflagration which may be conceived to have so got beyond control as to hold some one of the largest buildings in flames from top to bottom and from end to end." "Ten streams or as large a proportion thereof as the financial consideration will permit may be recommended for a compact group of large, valuable buildings irrespective of a small popu- lation." Fig. 109 f shows the number of fire streams, based on popula- tion, considered necessary by different authorities. * See previous reference. t Prepared from table and diagram, page 15, of "The Financial Man- agement of Water-works." E. Kuichling, Trans. Am. Soc. C. E., Vol. XXXVIII. FIRE PROTECTION. 355 It should be borne in mind that the quantities of water to be allowed for purposes of fire protection are in addition to the consumption for domestic, public, and manufacturing purposes. 10000 .20000 30000 10000 50000 60000 ,70000 80000 90000 100000 Population on Protected Area FIG. 109. Number of Fire Streams Required in Cities. In general, the amount of water required for fire protection is added to the maximum hourly or daily rate of consumption for other purposes, and provision is made for a total draft equal to this amount for a period of from one to six hours. The fire-hose in general use is 2% inches internal diameter, and the comparatively high velocities of flow when water is dis- charged through a nozzle at rates of from 175 to 250 gallons per minute result in a large loss in pressure owing to the energy consumed in overcoming the factional resistance of the hose. A like loss of energy occurs when water is drawn in large quantities from long lines of small pipe. In general, hydrants should be so placed that hose lines of a length greater than 500 feet are not required in residential dis- tricts, and of not more than about one-half that length in busi- ness or manufacturing districts. The hydrants in a residential 356 MAINTENANCE AND OPERATION. district, where in the majority of instances two good fire streams are sufficient, are usually placed about 500 feet apart; but since it is advisable to place these appurtenances at street intersec- tions, no fixed rule with regard to the distance between hydrants can be followed. When more than two streams are required the average lengths of hose used ordinarily exceed the figures stated. If 45 pounds be taken as the pressure at the base of the nozzle, the pressures required at the hydrants when the streams are flowing, and the best quality smooth rubber-lined hose of 2^ inches internal diameter is used, are about as fol- lows:* Length of hose. Size of smooth nozzle. i-inch. !-inch. i-inch. ii-inch. Pressure required at hydrant. 50 feet 47 Ibs. 1: 59 49 Ibs. i; : 62 67 72 52 Ibs. I 6 65 74 83 9i 56 Ibs. 8ij 92 106 " 120 " 100 ' 200 ' 300 ' . * , 400 500 ' . Since the pressures at the hydrants usually range from 75 to 100 pounds in the majority of instances, it follows that good fire streams cannot under ordinary conditions be delivered through more than 300 to 400 feet of 2j-inch hose. The hydrants in the commercial district should, therefore, be arranged with this fact in view, and the opportunity to concentrate the number of streams deemed necessary for efficient protection should be afforded. In cases where long lines of hose are necessary, or the hydrant pressures low, much of the energy used in forcing water through the small hose lines may be saved and made available at the nozzles by the use of two lines of hose, which are connected with a Siamese coupling to one or more lengths to which the nozzle * John R. Freeman, ''Some New Experiments and Practical Tables relating to Fire Streams," Jour. N. E. Water-works Assoc'n, Vol. IV; also "Experiments relating to Hydraulics of Fire Streams," Trans. Am. Soc. C. E., Vol. XXI. FIRE PROTECTION. 357 is attached. This saving^ is due to the fact that by the use of two lines from a hydrant the velocity of flow is decreased and likewise the friction Josses in the hose. Long lines of 4- inch pipe cannot, under ordinary conditions, be depended on to furnish a supply for more than one good hose stream, and in some cases not even one strong stream can be made available. With a given loss of head due to friction, the dis- charging capacity of a 6-inch cast-iron pipe is about three times, and that of an 8-inch pipe six times, that of a 4-inch pipe of equal length and under similar conditions. The loss of head in new, clean cast-iron pipe, due to friction, is about as follows for pipe of the diameters mentioned: Discharge, gallons per Loss of h sad in feet per 1000 feet. minute. 4-inch. 6-inch. 8-inch. IOO 200 300 400 SCOO 7-5 27.0 58.0 97.0 I .0 3-8 8.0 13-5 2O . Z 0.27 0-93 I .96 3-35 5 . 10 6OO 28. < 7 . OO The advantage of using 6-inch pipe for street mains instead of 4-inch is clearly indicated by the above table, and pipe of larger diameter than 4 inches should be used for mains whenever possible. The minimum sizes of pipe usually adopted for residen- tial districts are 6- and 8 -inch, and for commercial districts, 10- and 12-inch. The diagrams (Figs. 112 and 113) will be found useful in a study of the efficiency of a system as a means of protection against fire. The diagrams relating to the discharge of smooth nozzles and the friction losses in hose are based upon the experiments of Mr. Freeman, to which reference has been made. The pressures at the nozzles and at the hydrants are the pressures at these points when streams are flowing. If the elevations of the nozzle and the hydrant are not the same, an allowance for the difference in height should be made. 358 MAINTENANCE AND OPERATION. The diagrams showing the friction losses in cast-iron pipes are based on computations made by the Hazen-Williams for- mula: * v = 10 20 30 & 50 60 70 80 90 100 / / ' / ~_ / 40 : > 2fl / y X* 100 / 80 t 2 60 X 'V > / j ~ */ / \/ 20 -y X / ^- / / 20 30 t b 60 70 80 / / Pre ur ir. P r sq 1 1. y ^, r / ^ 10*0 / ^ -~ tie ^ J-- / / ^ ^ $0 J^* ^ y " &/ '"^t^ a ^- / ^ * Rft ^ X ~'*^^L NO' / / ^ / ^T ' ^~** / / ^X ^ ^^" y 0' ^, -^ ~z t ^ I 60 y ! *v ^ 1 / ^ X ? / S S V- ^ ' 1 / ' / A 1 * / I ~f / \ > / 7 r HEIGHT OF FIRE STREAMS ^ DISCHARGE OF SMOOTH NOZZLES. 20 / f A FRE 2CORDING.TO EMAN--S TABLES. y / ( ACCORDING EMAN'S TA TO BLES. " FRE 10 2 30 40 50 60 70 80 90 Pressure at Nozzle: 'Ibs. s M 10 20 30 40 50 60 70 80 80 100 Pressure at"Nozzle:'lbs. FIG. no. Height of Fire Streams and Discharge of Smooth Nozzles. in which v = velocity of flow in feet per second; c = coefficient of roughness, which has been taken as 130 * More complete diagrams based on this formula and comparisons with other formulae and data are given in a paper " Hydraulic Diagrams and Further Notes Upon the Hazen-Williams Slide Rule," by Leonard Metcalf, C.E.. Eng. Record, Vol. 47. FIRE PROTECTION. 359 for new, clean pipes and 100 for old and tubercu- lated pipes; Pressure at Nozzle: Ibs. 10 20 30 40 50 60 70 80 ( Pressure af3ozzle% Ibs.., 10 20 30 40 50 60 70 SO 90 TOO 10 20 30 40 50 60 70 80 90 Pressure at. Nozzle: Ibs. 10 20 30 40 50 60 70 80 Pressure at Nozzle: 90 100 FIG. in. Friction Losses in Ordinary Best Quality Smooth Rubber-lined 2. \ -inch Hose. r== hydraulic mean radius pipes; s = slope diameter in feet for circular head length* 3 6o MAINTENANCE AND OPERATION. The following example illustrates the use of the diagrams. Assume that a stream of 150 gallons per minute is required from a |-inch smooth nozzle at the end of 300 feet of hose. Then the pressure at the nozzle should be 45 pounds, and if the nozzle is 20 feet above the hydrant, the pressure at the hydrant should be 62 + 9, or 71 pounds. If the hydrant is supplied by a 6-inch pipe 2000 feet long, the pressure in the main to which the 6-inch line is connected should be about 73 pounds. Where hydrants are located on mains supplied through several pipes of different diameters, laid at different times, computa- tions of friction losses consume considerable time, and the results obtained are often very uncertain. ' A better plan in such cases is to experiment on the ground by attaching a pressure-gage to the main or a hydraixt and noting the indications at varying rates of draft. Loss of Head Due to Friction in I P p p p p p .r^ %, %s ' , V*^ r<~> -* * "* X 1 1 T ! B ^ v Xv / x ^ X X, \ ^ \ ^ X / NS N \ x^ \ "\^ \ 2 ** ^ ^\ "X X x X. ^ Ss x^ \ 2 X v^ j x^^ / x x ^^x^ ^x r^ / X ^ N "x^ "X, x,^ O 'x.^ ^x \ x H ^x^ x. 4-| A(\f\ x^ x^ ^5 ^x ** ^x,^ ^x / v - \ I J 500-^ ^^ s H -x T in -/ I = P P "X^ s 2 "g ^x. 2 "X^ v X x s \ ^x.^ / X. x s s/ ^X^ 2 g x/ s \ ' \ 2s x / \ 515 / ^^v X. x E "x^^^^ x x. 2000 $ / x X / nA- Xr^ ~ =Xt X X 5 x i 3000 3500 / 7000 -t- /. rT / ^ / per 1000 Feet of Pipe fiT m ' ouoi i g 1 \ \ Loss of Head Due to Friction 100 'eet per 1000 Feet of Pipe HE E CHAPTER XI. ACCOUNTS ACCURATE and detailed accounts of all funds received and expended for water-works purposes should be kept in suitable books, arranged in as simple form as possible consistent with an intelligible presentation of the facts. The larger part of the book-keeping of a system deals with the accounts of the individual consumers, as receipts for water supplied at meter or schedule rates, service connections, etc., and the items are usually entered in books to which the name registers has been applied. Since the number of bills rendered in the course of a year for the several items varies to a large extent, these items may be conveniently kept in three books, namely, a register in which all bills rendered for water supplied at schedule rates are entered, a register for meter accounts, and a service-connection register. The use of one book for all the above purposes is inconvenient, since but one person can have access to the accounts at any one time; the amount of space wasted is large, and the names of the consumers require rewriting at frequent intervals. The register containing the accounts of consumers to whom water is furnished at fixed rates may be arranged as follows: A line extending across two opposite pages of the book is allowed to each account, and the items are entered in columns under the following headings: Service number, Name, Address, and Rate for year ending .... (or Rate for six months ending .... ), the latter column being subdivided under the following headings: Amount of bill, Amount abated, Amount paid, Amount uncollected, and Date of payment. The items included under "Rate for " are repeated across the two pages of the register in order that a 361 362 MAINTENANCE AND OPERATION. number of successive bills may be entered opposite the name of a consumer. A similar arrangement may be used for the other registers by changing the column headings to conform to the purpose for which the book is intended. Or the accounts may be kept by the card system, in which case a card is used for each consumer. Advantages derived from the use of cards for this purpose are: that several clerks may April 1, 1904^ WATER RATE. Service No. Amount Abatement Total Paid Credit to Water Maintenance dcct. FIG. 114. Coupon. work on the accounts at one time, that changes due to the moving of consumers from one building to another, etc., may be adjusted more readily, and that the paid and unpaid accounts may be kept in separate files. Two disadvantages of the card system are that all figures must be taken off in computation books before total amounts can be ascertained, and the liability that cards may be misplaced or lost. The bills are made from the data contained in the inspection, meter, and service records, and all bills rendered by the depart- ACCOUNTS. 3 6 3 ment should have coupons attached upon which the date of bill, service number, name of consumer, amount of bill, etc., are noted. These coupons are torn from the bills by the person to whom payments are made, and returned to the water-works office. In order that the coupons of bills made for different purposes may be easily distinguished, the bills and attached coupons may be printed upon paper of different tints, or the type or the color of ink used on the coupons may be varied. The amount of a bill is entered in the proper column of the register before the bill is sent out. Upon receipt of the coupon from the collecting officer the amount paid or abated is entered in the register. The total receipts on the different accounts as shown by the coupons are computed and the results entered in the cash-book or journal daily, weekly, or monthly, as may be found convenient. The coupons should be preserved until the accounts are made up for the year, and may then be destroyed. At the close of the fiscal year the total footings of the columns of the registers should be ascertained. The aggregate amount of the bills rendered should equal the aggregate totals of the various subdivisions of the register, and the aggregate amount of the payments should equal the totals of the entries made in the cash-book or journal. In general all bills rendered by the water department are payable within thirty days, but the instance is extremely rare where all bills are paid before the expiration of that period. Du- plicate bills are occasionally rendered, but usually statements of accounts due, or notices so worded that the attention of the delin- quents is called to the fact that bills are overdue, are sent to the consumers after a reasonable time has elapsed. In case the statement or notice does not accomplish its purpose, a shut-off notice is sent, and if this notice is disregarded the supply is dis- continued until the arrears are paid. The receipts from various sources and the expenditures incurred for construction, maintenance, and operation may be kept in a cash-book, journal, and ledger of the ordinary form. Or sepa- rate sets of books may be kept for the Construction and Main- tenance accounts. Or in the case of small works where the number of detailed accounts kept is small, the entries may be 364 MAINTENANCE AND OPERATION. made in a single book under headings arranged on two pages somewhat as follows: RECEIPTS. CONSTRUCTION. MAINTENANCE. Date. Received from: Total amount. Loans. Services. Sundry acc'ts. Schedule rates. Meter rates. Sundry acc'ts. EXPENDITURES. CONSTRUCTION. Date. Paid to: Total amount. Distribution. Services. Meters. Special. MAINTENANCE. Administration. Pumping. Care of appurtenances. Repairs. Meters. Sundry acc'ts. The receipt or payment is entered in the column headed ' 'Total amount," and also credited or charged to the proper account as indicated by the headings. The footings of the columns are carried forward from one page to the next, and the condition of the accounts, or any one account, can be readily determined when desired. All bills, particularly those for supplies and material purchased, should be filed after payment for future reference. In order that the data with regard to items of cost may be accurately compiled for the various records mentioned in Chap- ACCOUNTS. ter I, or for other purposes, both Force and Material accounts should be kept. These accounts are made daily and filed at the water-works office by the foremen or inspectors in charge of the various portions of the work. The form shown below is adapted for use with a small force working under the direction of a foreman or inspector. The blank forms are about 3j"x6" and may be carried conveniently in the pocket in a loose-leaf binder or in pads. The names of the employes appear on the sheet, the work performed is noted in the space at the head of a column, and the time given by each employe is entered below WATER-WORKS FORCE ACCOUNT. Oct. 10, 1904. Leak 10" main, Pine Street. Repairing hydrant No. 3, Main Street Setting meter No. 4, PineStreet. Service connection, W. H. Rice. John Williams, foreman. . . Henry Murray 5 hrs. 6 " 6 " 6 " 6 " ihr. 3 hrs. 3 ' |hr. i " 2 J hrs. 2 " 3 H Kelley J Smith Fred White opposite the name. The pay-rolls are made from the daily Force accounts. Daily reports of the amount of material used, the character of the material, and where used, should be made upon prepared forms or upon the back of the Force sheet. In the case of continuous work, such as extensions of mains, etc., the time of the individual laborers may be more conveniently kept in a time-book, and the aggregate time entered on a Force sheet. This time may be apportioned to items such as teaming, excavation, pipe-laying, back-filling, etc., and data regarding the progress of the work, the material received, removed, or used, should also be given. A Stock account is very desirable and may be kept in a book prepared for that purpose, in which the amount, kind, and cost of material purchased and used is entered. At the close of the year the figures should be checked by making an inventory of the stock on hand. CHAPTER XII. FINANCIAL MANAGEMENT. To the requirements that extensions of, or additions to, a system of water- works be made in accordance with good engineer- ing practice, that the efficiency of a system from a mechanical standpoint and the sanitary quality of the supply be maintained or improved, should be added the requirement that the depart- ment be operated on a business basis. In general, conditions favorable to such operation more often obtain in works owned and operated by private companies than when these are strictly municipal enterprises. Even in the latter instances, however, the affairs of the department may be conducted in a business- like manner if political or personal interests are eliminated. At the outset a distinction should be made between funds expended and obtained for purposes of construction and of main- tenance. The cost of the original works is charged to the Con- struction account, and expenditures for extensions, additions, or improvements are also properly chargeable to that account. Under this heading are included the cost of new mains and appurtenances, services, meters, pumping machinery, reservoirs or stand-pipes, filtration works, and expenditures incurred for the improvement or extension of the source of supply. Expenditures for the purpose of renewing portions of the system, such as mains and appurtenances, pumping machinery ? etc., which are either worn out or of insufficient capacity, are usually charged to the Construction account. Current practice is in this respect, however, varied. In some cases the cost of renewing minor portions of the works, as small mains, services, and meters, is charged to the Maintenance account or is divided between the two general accounts. In any case it is advisable 366 F1N/1NCI/IL MANAGEMENT. 367 that the accounting of renewals be made in such manner that expenditures for original construction and for renewals may be distinguished from each other. Funds for purposes of construction are usually provided by the issue of bonds or notes. When the works are owned by the municipality, these bonds or notes bear interest at certain speci- fied rates, usually 3 or 4 per cent per annum, and are payable at a stated time, usually ten, twenty, or thirty years, after the date of issue. In some municipalities the cost of extensions is paid from assessments upon abutting property. Minor items of construction, as yearly expenditures for new service connections or meters, are often, although charged to the Construction account, paid for from the surplus annual revenues. Extensions of existing works which have as their object the improvement of the efficiency of the system are often made with- out regard to any financial benefit which would be directly derived therefrom. Such is not usually the case, however, when mains are extended in new streets, in streets not previously supplied with water, or in private ways. Mains are not generally laid in public streets unless the revenue to be received from the sale of water will yield a fair return upon the investment. When the revenue based on the established schedule of rates is insuffi cient for this purpose, and the indications are that sufficient revenue may be received in the near future, extensions are occa- sionally made, provided the water-takers served by the particular extension agree to pay, as special water rates, a sum equivalent to the fair return for a stated period of time. These special rates are fixed to produce an income of from 4 to 7 per cent annually on the cost of the work. Where extensions are made in private ways, the entire cost of the work is usually borne by the parties benefited, although provision may be made that the cost be refunded at such time as the ways become public. The cost of service connections outside street limits is borne by the consumers. The cost of connections within street limits is in some cities and towns assumed by the department; in others a stated sum varying with the size of connection is charged. As a general rule, service connections are not laid unless the revenue 368 MAINTENANCE AND OPERATION. to be derived therefrom is at least equal to the established annual rate for a single faucet. Water-meters should be owned and controlled by the water department, and not by the individual consumers. The cost of meters is ultimately borne by the consumers in either event, and meters may be removed for testing or repairs, or replaced, with less friction between the department and the consumers in the former instance than would be the case in the latter. All expenditures incurred for the maintenance and operation of a system of water- works are charged to the Maintenance account. The items of expenditure included in this account are the salaries of administrative and executive officials, office expenses, wages of permanent employes, pumping expenses, purification expenses, care and repair of the system; in brief, all expenditures incurred in maintaining the system in good condition and for its opera- tion. The annual interest charges on outstanding bonds or notes are also paid from the Maintenance account. In addi- tion, payments to a sinking-fund which shall be sufficient to pay the outstanding indebtedness when it becomes due are made from this account, where the works are owned by the municipality. Where works are owned by private companies, similar annual pay- ments may be made to a depreciation fund, as a provision for the replacement of portions of the system when this becomes necessary. In this latter instance a reasonable profit in addi- tion to the foregoing charges is to be desired. The funds required to provide for the varied expenditures for maintenance and operation are derived from the receipts from the sale of water, minor receipts for repairs and the sale of mate- rial, and from the general tax levy. These receipts constitute the Income account. The principal sources of revenue are the water rates and the appropriation from the tax levy, and the proportion of the annual income derived from the former, as compared with that derived from the latter, is subject to variation within wide limits in different communities. Primarily the water rates represent the value of the water actually or presumably used by the individual consumers, and the appropriation in a measure represents the value of the fire protection and other indirect benefits afforded by the works. FINANCIAL MANAGEMENT. 369 The several departments of a municipality should be considered upon the same basis as private persons, and the water depart- ment should receive funds in the form of cash payments or credits for all water supplied for municipal purposes. This includes water used in public buildings, fountains, for sewer flushing, street sprinkling and cleaning. Water rates are divided into two general classes: schedule, fixed, or assessed rates, and meter rates. The former are based, not upon the amount of water actually used, as are the latter, but upon the amount presumably used, the convenience or luxury derived from the practically unlimited use of the supply, the opportunity afforded for the waste of water, or a combination of these items. The methods by which the amount of the annual rate is ascertained in a given instance differ widely in practice. In general, schedule rates are based upon one or more of the fol- lowing items: size of lot, street frontage, assessed value of build- ing supplied, number of persons supplied, number of rooms, number and kind of fixtures, and annual rental value of premises. In the majority of works the rate annually assessed upon a build- ing or apartment occupied by a single family is limited by a so- called maximum rate, which is usually from fifteen to twenty- five dollars. Rates for metered water are either uniform, i.e., one price per unit of quantity regardless of the amount consumed, or vary with the quantity furnished. In this latter case a certain price per unit quantity is charged for the supply up to a definite amount, and reduced rates are charged for excess quantities. The following is an example of a graduated schedule of this kind: For quantities not exceeding 3000 cubic feet per quarter, per 100 cubic feet So. 20 Excess above 3000 up to 10,000 cubic feet per quarter, per 100 cubic feet o . 15 Excess above 10,000 up to 50,000 cubic feet per quarter, per 100 cubic feet o . 10 Excess above 50,000 cubic feet per quarter, per 100 cubic feet o . 075 A graduated scale which offers any inducement for con- 370 MAINTENANCE AND OPERATION. sumers to waste water should never be established. A schedule of this character would read somewhat as follows: For quantities not exceeding 3000 cubic feet per quarter, per TOO cubic feet $o . 20 For quantities not exceeding 10,000 cubic feet per quarter, per 100 cubic feet o . 15 For quantities not exceeding 50,000 cubic feet per quarter, per 100 cubic feet o . 10 For quantities exceeding 50,000 cubic feet per quarter, per 100 cubic feet o . 075 Under a schedule of this form a consumer would, in cases when the consumption approached one of the limits given, be inclined to waste water in excess of that limit in order to realize the benefit of the lower rate. Whenever water is sold by measure, a definite sum is fixed as the minimum annual rate regardless of the actual registra- tion of the meter. The minimum rates established in different works range from about five to fifteen dollars per year. Two principal reasons for the establishment of a minimum rate are advanced. The first, which maybe termed the financial reason, is that a certain amount of money is required each year to meet the fixed charges of maintenance and operation, including inter- est charges and sinking-fund requirements. The interest on outstanding bonds, sinking-fund payments, the salaries of per- manent officials and employes, and the cost of repairs are affected but slightly, if at all, by variations in the total amount of water annually furnished. By the collection of minimum rates, funds applicable to the partial payment of these fixed charges are assured. The second reason is that as a sanitary measure exces- sive economy in the use of water should not be encouraged, and under the minimum rates in use an ample supply for an average family, if waste be restricted, may be obtained for all domestic purposes. Established rates for water supplied by meter measure- ment to domestic consumers range from twenty to thirty cents per thousand gallons, or about fifteen to twenty-five cents per one hundred cubic feet. In an ideal system the annual revenue from rates and the appropriation should equal the annual expenditures plus the FINANCIAL MANAGEMENT. 371 contribution to the sinking- or depreciation-fund and the inter- est on the outstanding bonds or notes; the cost of the service should be equitably divided between the consumers and the taxpayers, and the rates should be equitably apportioned among the individual consumers. This result can, however, be only approximately realized under the most favorable conditions. Usually the annual receipts from the sale of water show an in- crease year by year, and the surplus revenue is used to make larger contributions to the sinking- or depreciation-fund. Or the amount of the hydrant rental or contribution from the general tax levy is diminished. In addition to the direct benefits which the water-takers of a community receive from a system of water-works, the instal- lation of works of this kind results in more or less indirect bene- fit to both consumers and taxpayers. In consequence of the existence of water-pipes in the public streets, real estate abut- ting on these streets is increased in value, the rental value of tene- ments and apartments supplied with water is likewise enhanced, and a saving in fire-insurance premiums is effected. The capacity of a system of water-works is increased, often to considerable extent, to provide for the large rates of flow necessary for efficient fire protection, and also as a provision for future demands, above the ordinary requirements of a community for domestic and manufacturing purposes. A certain proportion of the annual expenditures may, therefore, be equitably assessed upon taxable property. According to various authorities, the provisions for fire protection increase the cost of a system of works about one- third. The expenditures for maintenance and operation are likewise somewhat increased, hence it is assumed that 50 per cent of these expenditures, including interest and sinking-fund charges, may be taken as an approximate measure of the value of the fire protection and other indirect benefits afforded by the works, and may be properly raised by general taxation. The remaining 50 per cent of the annual expenses may then be appor- tioned among the individual consumers. The equitable division of this portion of the expenditures is best accomplished by the use of meters. The method for the apportionment of the cost of maintain- 37 2 MAINTENANCE AND OPERATION. ing and operating a system of water-works outlined above is rarely followed in practice at present, particularly in the estab- lishment of a schedule of water rates for new works. It is, how- ever, of value in the adjustment of existing schedules. Rates established in accordance with the method outlined are based both upon the cost and the value of the service, and these two factors constitute the only proper and reasonable basis for such establishment. Since the cost of service is affected principally by the local conditions which obtain in a given case, and the inter- est charges and sinking- or depreciation-fund requirements de- pend upon the cost of construction, the cost of service may be widely different in any two communities. This difference is particularly marked if comparisons are made between works respectively supplied by gravity and by pumping. Rates estab- lished by the method indicated would, when based upon the cost of maintaining and operating a new system with a comparatively small number of consumers, be excessive and the increase in new business, in consequence, limited. Furthermore, the aver- age consumer pays little or no attention to the cost of deliver- ing water upon his premises, but bases his criticisms with regard to the reasonableness of rates upon comparisons made with schedules which obtain in adjacent cities or towns. It is the usual custom, therefore, when a supply of water is introduced in a city or town, to base the schedule of rates in large measure upon the schedules in use in works in close proximity to the case at hand. The yearly deficit is then made up by appro- priations from the general tax levy, and during the first years of operation the payments to the sinking-fund are small. The appropriation from the general funds of a municipality for water- works purposes is usually made in the form of hydrant rental, i.e., a specified sum is paid for each public hydrant connected with the works. Since funds are necessary at all seasons of the year for the payment of bills incurred by the department, it is customary to collect the whole or a portion of the water rates in advance. Bills for water furnished at schedule rates are usually rendered annually or semi -annually, and are payable in advance. Where water is furnished at such rates, the total annual revenue to be FINANCIAL MANAGEMENT. 373 received for a given year may be quite closely computed, and this fact constitutes the chief advantage of this method of assess- ment. On the contrary, the revenue to be derived from the sale of water by meter measurement is often very uncertain. The minimum rates may be collected in advance, but the total receipts can only be approximately ascertained until the close of the fiscal year. Meter bills are usually rendered quarterly or semi- annually to domestic consumers, and monthly or quarterly to manufacturers or other large consumers. Water furnished for manufacturing purposes is usually metered, and the rates at which it is sold, when the domestic consumption is not metered, are, in general, arbitrarily fixed. With a view to the encouragement of manufacturing enterprises the meter rates, particularly when on a graduated scale, are often made purposely low. In such instances a change from the schedule to the meter system of furnishing water to domestic consumers results in a decrease in the annual revenue unless the schedule is revised. Owing to this fact, due consideration should be given to the cost of delivering water, when manufacturing rates are established, in order that radical changes in the schedule may be avoided when the domestic consumption is also metered. The proposition is often advanced that when water is fur- nished by measurement all consumers should be treated alike and on an equal basis, regardless of the quantities consumed, i.e., the water should be furnished at a uniform rate per unit quantity. An adherence to a uniform meter rate would in many cases cause large consumers to obtain water from sources other than the public supply, to the financial disadvantage of the department. Such conditions may also obtain that the quantities used by a few consumers constitute a considerable proportion of the total consumption, and therefore a material reduction in the unit cost of delivering water results. Under a uniform schedule the small consumers would then receive the benefit of the reduced cost. In general, the adoption of a graduated scale is consistent with good business policy, and such schedules, if good judgment is exercised in their establishment, do not favor large consumers at the expense of the small or domestic consumers. 374 MAINTENANCE AND OPERATION. An established schedule of rates should not be changed unless the results obtained from a study of the financial and physical condition of the works, present and prospective, indicate the necessity for or advisability of such change. In lieu of a gen- eral reduction in rates, discounts are allowed in some works on all bills paid within a specified time after they are due. This discount is usually in the form of a percentage; as, ten per cent of the amount of the bill if the same is paid within ten days from date, and five per cent if paid within twenty days. If unfore- seen events necessitate changes in the schedule, the changes may be more readily effected under a discount sys em than under a fixed-rate system. Although in all well-managed works the loss from non-payments of rates is insignificant in amount, more or less time is used and friction occasioned in the collection of overdue water rates, hence cash customers may very properly be given the benefits arising from the discount plan. A change from the schedule to the meter basis of rate assess- ment, with the accompanying general introduction of meters, in an established system of works is usually productive of the following results: First, an increase in the expenditures for clerical and re- pair work, inspection, and interest and sinking-fund charges. Second, a decrease in the expenditures for fuel, and possibly to a slight extent in the other pumping expenses when water is pumped. Third, a decrease in the revenue from consumers, or, Fourth, a redistribution of the charges for water furnished individual consumers. If the decrease indicated in the second item exceeds the in- crease due to the first, the change is advantageous to both depart- ment and consumers. Such, however, is not the result ordinarily obtained. However, the diminution in the annual consumption resulting from the introduction of meters, considered in a pre- vious chapter, may be advantageous if expenditures for addi- tional construction or for purification are materially reduced thereby. If the annual income is just sufficient to meet the charges for maintenance and operation, a reduction in the amount of revenue is not desirable, and the fixed charges cannot be met FIN 'A 'NCI A L MANAGEMENT. 375 by a uniform minimum rate charge unless that charge be exces- sive. As a means of providing revenue sufficient to meet the fixed charges the graduated minimum rate method used by Mr. Freeman C. Coffin, C.E., is of value. The minimum rates established by this method, and the quantity of water furnished to a consumer under these rates, vary with the kind of fixtures supplied from the metered service connection. The minimum meter rates established at Merrimac, Mass., afford an illustra- tion of the use of a graduated minimum scale. In these works a minimum charge of six dollars per year is made where ordinary faucets only are supplied, eleven dollars per year for faucets and water-closets, fifteen dollars per year for faucets, water-closets, and bath-tubs, and twenty dollars per year for the above fix- tures with hose, etc. This latter charge is the highest minimum charge made for water supplied to a single family. The minimum charges are payable quarterly in advance, and excess bills based upon the regular schedule are rendered at the end of each quarter. Provision for the cost of maintaining meters is made in some works by the collection of meter rentals. An ordinary service- meter set in place costs from ten to sixteen dollars. The expense of maintaining these small meters is about as follows: Interest on first cost at 4% per annum $o . 40 to $o . 84 Contribution to sinking- or depreciation-fund, 4% of cost. . 0.40 to 0.84 Annual maintenance: reading, inspection, testing, repairs, and clerical work i . oo i . oo Total annual maintenance $r . 80 to $2 .68 At the expiration of twenty years the sinking-fund will be sufficient to pay the original cost of the meter or to replace it, and the life of an average meter is usually assumed to be equal to that period. Since this life is, in general, dependent upon the character and amount of water passed through the meter, the duration of service of a meter may be more or less than twenty years. Within this limit the items of maintenance affected by the amount of water consumed through a metered service are those of repair and testing only, and since these are a small pro- portion of the total annual expense, the cost of maintaining meters may be equitably divided equally among the individual MAINTENANCE AND OPERATION. consumers without regard to the amount of water furnished. The sum of two dollars per meter is, therefore, usually charged for the annual rental of an ordinary service-meter. This sum is ncreased with the increase in size of the meter in proportion to the additional interest, sinking-fund, and repair charges. A further charge is at times included in the rental of large meters to provide for the amount of water which may pass these meters without registration. This charge corresponds to the value of the possible unrecorded flow at the established rates. The following charges may then be, and are usually, made when water is furnished through metered service connections: First, an annual rental depending upon the size of meter which will meet the expense of its maintenance, and also pro- vide for the under-registration of large meters at small rates of flow. Second, a minimum annual rate which shall provide in a measure for the fixed charges for the maintenance and operation of the works, and which shall prevent undue economy in the use of water for domestic purposes. Third, a graduated scale of rates for metered water. CHAPTER XHI. RULES AND REGULATIONS. RULES and regulations governing the use of water are usually prescribed by the water commissioners where the works are owned by a municipality, and by the company when these are private enterprises. Such rules and regulations as are estab- lished, or a^e in use, should be explicit and should be impar- tially enforced. A limited number of rules which are avail- able in printed form, and are strictly enforced, are of more value in the management of water-works than a large number of regu- lations inscribed in records and forgotten or rarely observed by the parties concerned. The following directions and reservations are commonly included in the rules established by various works. An application for a supply of water is required to be made upon a prepared form and signed by the owner of the property supplied or his agent. In some works the material and labor required for making a service connection is furnished, and the connection made by the department from the street main to the stop- and waste-cock in the cellar of the applicant's building. In other works the pipe is furnished and laid with the necessary appurtenances by the de- partment to the street line only, all work beyond the street line being performed by plumbers. Or the entire work is performed by licensed plumbers, although in some cases the street main is tapped by employes of the department. Where any portion of the work of making a service connection is performed by plumbers, permits are issued by the department covering each connection made, returns upon prepared forms of the service and fixtures connected therewith are required, and the work is inspected by 377 MAINTENANCE AND OPERATION. employes of the department before it is concealed. The size of pipe, and the material of the pipe and fittings to be used, are usually specified by the department. The method of making service connections, and the charges to be borne by the applicant therefor, should be clearly stated in the rules and regulations. When the entire service connection from the street main to the building supplied is laid by the department, plumbers or other unauthorized persons are not allowed to disturb in any manner the pipe or fittings placed by the department. Notice of alterations in, or additions to, the fixtures origi- nally supplied is required from the water-taker or the plumber doing the work. In some works no notice is required where alterations made consist merely in the replacement of a fixture by another of the same class. Unnecessary waste of water is prohibited, and water-takers are required to maintain the interior piping and fixtures con- nected thereto in good condition and repair. Consumers are not allowed to furnish water to persons not entitled to its use, nor to conceal the purposes for which water is used. Where service connections are not metered, the use of hose for sprinkling street or lawns or for irrigating gardens is usually restricted. Regulations restricting the use of hose are more readily enforced if the hour or hours of the day during which such use is permissible are stated explicitly. When meters are owned by the department and are located in buildings, consumers are usually held responsible for damage to the meter due to their negligence or to freezing. Consumers are also required to protect pipes and fixtures on their premises from freezing. The times at which bills are rendered and are due are stated, and when several tenants are supplied through a single service- pipe the property-owner is held responsible for the water rates. When water is furnished at schedule rates, discounts or abate- ments are usually allowed, provided that notice is given when premises are vacant in order that the water may be shut off if the department so desires, and that fixtures not in use may be sealed. RULES AND REGULATIONS. 379 Officials or employes of the works are allowed to enter the premises of water-takers at all reasonable times to inspect the service, and to test, repair, or replace meters. The supply of water may be interrupted in case it becomes necessary to. shut off a main for repairs or other purposes. Pre- vious notice of such interruption is usually given whenever pos- sible. The water is usually shut off from the premises of any taker who fails to comply with the rules and regulations or neglects to pay water rates after having been notified to do so. In these instances a charge is usually made for letting on the water after the cause for complaint has been removed. The department usually reserves the right to place a meter upon a service and to charge for water supplied at meter rates. When connections are desired for purposes ot fire protection, detailed plans ot the location of all pipes, valves, hydrants, etc., are required. All outlets from connections of this nature are sealed, the seals to remain unbroken except in case ot fire or when water is used for tests, unless the connection is metered or pro- vided with other devices for indicating a flow of water through the pipes. Connections between the fire- pipes and those in ordi- nary use are not allowed. CHAPTER XIV. ANNUAL REPORTS. THE water commissioners of a city or town which is provided with a public water-works system annually present to the munici- pality a report regarding the system under their direction and con- trol, in accordance with the provisions of legislative acts, municipal ordinances, or as a result of established custom. These annual reports should furnish information concerning the condition of the works, financial and otherwise, the amount and nature of the work performed during the period covered by the report, recommendations with regard to any action that the municipality should take, and facts which will enable the community to deal intelligently with the recommendations made. A brief statement of the financial condition of the works is usually presented in the reports. This statement should show the cost of the works, the amount of the outstanding bonds or notes, the amount of the sinking-fund, and the net debt at the date the report is made. The work performed for purposes of construction should be briefly described, and if any portion of this work has been done by contract, information with regard to the nature of the work, the name of the firm or individual to whom the contract was awarded, the amount of the contract, and the progress made, is usually given. When competitive bids are received a summary of the bids may be included. Statements with regard to the extensions of main pipes and services, and the additional hydrants, valves, meters, etc., placed during the year, may be made in tabular iorm, similar to the forms followed in the construction records. Alterations in or renewals of any parts of the existing works should be treated in similar manner. The tabulations may be supplemented by 380 ANNUAL REPORTS. 381 ~^^ . such explanatory matter as it may appear necessary or advisable to append thereto. Data with regard to the total amount of pipe of the several diameters, the total number of valves, hydrants, service connections, and meters of the several patterns and sizes in use, are to be desired. The recorded results of such observations as are made of the precipitation on the catchment area, the yield of this area, or the flow of streams, and the meteorological observations, should be presented in more or less detail. Data with regard to the con- sumption of water and the operation of pumping or purification plants should also be given. The annual financial statements should be made with a view to the preservation of data of value or interest to the department and the community rather than to the gratification of the curi- osity of a few inquisitive individuals. The sums received from various general sources and the expenditures for construction, maintenance, and operation should be stated in concise form. Financial statements covering pages of detail regarding the amounts paid various persons or corporations for labor, mate- rials, etc., are of little value as compared with summarized state- ments of total expenditures for pumping, purification, repairs, maintenance of meters, hydrants, etc. Summarized statements of the cost of maintaining and operating water-works make the reports of value, not only to the municipality served by the works in question, but to the water departments of other cities and towns. Water-works officials may derive much of benefit at times from the reports of other works, particularly if data upon different subjects can be compared upon a uniform basis. Means for such comparison are afforded by the use of established forms, and the form for statistics adopted by the New England Water- works Association is now used by a number of public water departments. This form is given on the following pages. 382 MAINTENANCE AND OPERATION. SUMMARY OF STATISTICS FOR THE YEAR ENDING In form recommended by the New England Water- works Association. WATER-WORKS. (City or Town.) (County.) (State.) GENERAL STATISTICS. Population by Census of 1 9 , Date of construction, By whom owned Source of supply, Mode of supply (whether gravity or pumping) , PUMPING STATISTICS. i. Builders of Pumping Machinery, . . a. Kind, b. Brand of coal,, 2. Description of fuel used, c. Average price of coal per gross ton, delivered, $ .... d. Percentage of ash, [ e. Wood, price per cord, $ 3. Coal consumed for the year, Ibs. 4. [Pounds of wood consumed]-f-3 = equivalent amount of coal, Ibs. 4 70.80 25.20 20.60 75 IOOO 6 1 .00 19.50 19.40 IOOO 5000 59-30 I7-50 17 .60 5000 IOOOO 47.10 10. 70 29. 10 Over 10000 52.60 16. 70 The following interesting comparisons may be made of the preceding tables, omitting consideration of the first three groups FRANCHISE. WATER RATES. DEPRECIATION. 403 embracing annual consumption of water from i to 15 million gallons: Average total gross earnings of private plants, per million gallons. .$i 13 .42 Per cent of total gross earnings. Average gross income private plant, less hydrant rent 73-7 Average gross income private plant, less cost of production 54-2 Average cost of production and taxes 45.8 Average cost of production, less taxes 38.9 Average gross income of municipal plant 63 . 6 Average cost of production of municipal plant 32.5 Average rate of interest which gross earnings, less taxes and cost of production, will pay on private investment is shown to be. . 5 . 65% Deductions made from the foregoing table show the excess income of the private water-works over municipal water-works, amounting to $41.28, to be distributed as follows per one million gallons: Average hydrant rents $29 . 83 Average taxes 7-83 Income from commercial sources 3-62 $41.28 That portion of the total gross income which remains after deducting the cost of production and taxes is seen to pay an average of 5.65 per cent on the average investment. Many of the public-service corporations mortgaged the water-works prop- erty to raise the funds for construction, and, from sources of infor- mation independent of the report referred to, it is found that out of a total of 358 private water-works in 27 different States scattered throughout the Union 61.2 per cent floated securities at 6 per cent, and that the average rate of interest of all the securities is 5.82 per cent. It is also noticed that the cost of production of the municipal plants is $7.26 per million gallons less than the corresponding cost, exclusive of hydrant rent and taxes, of private plants a difference due largely to the greater amounts expended in salaries under private management. The discrepancy is not material except in relation to the larger plants, where it is quite as likely to be due to conservatism on the one hand as to liberality on the other. The discrepancies in three groups of plants 404 FRANCHISE. WATER RATES. DEPRECIATION. would indicate such a probability and that an average might consistently be taken of the cost of production of those groups of plants where the difference is material. The predominating character of the system of water-works, whether gravity or pumping system, would necessarily influence the average in the respective cases. Were the discrepancy to be averaged it would make the aver- age rate of interest on the average investment scarcely 6 per cent. It is apparent, therefore, that the statistics show in a general way little or no speculative value in private water-works property as a class, also that the average income has been insuffi- cient to provide a sinking-fund to cover depreciation resulting from the progressive deterioration of the physical property dur- ing the usual life of a limited franchise. This condition of income of water-works operated under a limited franchise must sooner or later react disastrously and represents a substantial foundation for the claim now frequently heard of the importance of the unlimited franchise as applied to the successful operation and maintenance of this particular form of public-service property. It is also clear that a 4 or 5 per cent investment under an unlimited franchise giving good ser- vice would be worth more to an investor and would prove more satisfactory to the consumers than a 6 per cent investment under a twenty-year franchise with every incentive offered at times to squeeze the service in order to protect the investor from loss through unavoidable depreciation and the uncertainty of the future when the franchise shall have expired. It is quite certain that the influence of metered services instead of the predominating influence of the annual rate system during the past experience of water-works public- service corporations would have acted as a protection to the water-service patrons and the investor jointly by eliminating an incentive to economize unduly and eliminating also the losses attending the waste of water and service which has prevailed to a greater or less extent under the influence of the annual rate system. So long as water service is considered a commodity the income from the sale of it under private management should pay the interest on the investment in physical property actually required FRANCHISE. WATER RATES. DEPRECIATION. 405 to produce the commodity, a sinking-fund to redeem the invest- ment eventually and to renew the physical property as it becomes useless, operating expenses, minor repairs, taxes, insurance, and in addition a reasonable surplus to meet emergencies. The longer and more secure the iranchise under which a private property is built and operated the lower should be the rate of interest and sinking-fund. A municipality operating its own water-works as though producing a commodity must necessarily follow a similar course, except that the interest and sinking-fund in part may be, as they usually are, a tax upon the property, and the income from the consumers may be limited to the actual cost of production plus a part of the sinking-fund and an excess to cover emergency expenses and repairs. But a city is privileged to cease treating the water service as a commodity, or to deliver the water at cost or below, and to provide for a deficit in any amount by appor- tionment from the general fund of the city, or by a special or general tax upon the property of the city, or any combination of these facilities that may be convenient and legal. The de- parture from the commodity basis is not liable to result in any economy or improvement of the water service to the consumer or the public generally, and is rather a dangerous expedient for small towns to adopt, as pointed out on preceding pages. The method will prove a fitting companion to the annual rate basis of dispensing a water service, for the reason that it places no check upon extravagance or waste, and presents no lesson in the matter of either personal or civic economy. Moreover the burden of the expense attending either the reckless or extravagant use of the water service falls, as a rule, most heavily upon the provident rather than the improvident, upon the careful rather than the careless or extravagant citizens. Among the objections to the general use of a water-meter, the prejudice or misunderstanding of the general public is more easily overcome than is the objection of the owners of rental property who desire to avoid responsibility for the careless use of fixtures by tenants. Experience will usually overcome preju- dice in this regard, but some method may be necessary to com- pel the owner of rental property to make repairs which he per- 406 FRANCHISE. WATER RATES. DEPRECIATION, sistently neglects or will not make voluntarily. It is clear as a matter of self-protection that the tenant will insist upon freedom from waste through leaky fixtures, but has no power to compel the owner to remedy the defect. The right to shut off the water should be exercised with discretion in such a case and need not be exercised at all if the owner, after due notice, fails to make the repairs, provided the value of the water service so wasted can be charged against the property and legally become a first lien against it. A law or ordinance of this character or a simi- lar one would prove effective. The method of dispensing a water service by definite volume must finally prevail, and with a view of facilitating the compu- tation of a gross income a table is prepared, based upon a general average but somewhat modified cost of producing the water service contained in Table IV. The computation also embraces sepa- rately the elements of interest and sinking-fund when this support is to be provided. The computations are intended simply as a guide to the judgment, and the cost of production is regarded simply as a base rate subject to modification in particular cases, as indicated in the memoranda immediately following the table, in instances where more definite data are not available. The cost of production is supposed to embrace all of the charges, such as salaries of administration and operation, wages, insurance, fuel, supplies, and other minor items of cost. The average working pressure of the works embraced in the computations of Table V is 60 pounds, and fully 85 per cent of the works have pumping machinery. The average salaries of administration and operation are 2 1 per cent, and average wages 26 per cent of the total cost of produc- tion, between the limits of 100 and 1000 million gallons annual consumption. Taxes should be added to the cost of production given in Table V whenever they become an element of the annual expense of operation. It does not follow from an inspection of the table that a flat meter rate is suggested, but that in each particular case, after the cost of production shall have been modified to suit the locality FRANCHISE. WATER RATES. DEPRECIATION. 407 and after such additions to cover interest and depreciation of value of the physical property shall have been made, the final TABLE V. BASE RATE PER MILLION GALLONS. A verage Cost of production plus interest on average Average annual consumption in million gallons. investment per million gallons annual con- Average cost of production. investment at 4% 5% 6% 7% 8% sumption. i to 15 $4692 $146 $334 $381 $427 $474 $521 IS 25 2168 96 183 204 226 248 269 25 5 1663 59 I2 5 142 J 59 175 192 50 100 1209 46 94 106 119 I 3 I 143 100 150 1010 37 77 88 98 108 118 150 250 858 33 67 76 84 93 IO2 250 500 645 25 5i 57 64 70 77 500 750 632 23 48 55 61 67 74 750 1000 640 20 46 52 58 65 7 1 1000 5000 622 18 43 49 55 62 68 5000 10000 600 *7 4i 47 53 59 65 i oooo and over 568 16 39 44 5 56 61 1 The cost of production of Gravity plants 150 to 10,000 million gallons and over is 80 to 60 per cent of stated cost of production. Pumping-plants 1000 to over 10,000 million gallons of high-grade engines pumping water once, as tabulated. Pumping-plants 1000 to over 10,000 million gallons of high-grade engines pumping water twice, add 40 per cent to tabulated cost of pro- duction. Pumping-plants 100 to 750 million gallons of medium-grade engines pumping water twice, add 40 per cent to tabulated cost of production. TABLE VI. AVERAGE COST OF FUEL FROM REPORT OF COMMISSIONER OP LABOR. 1 Annual consumption in million gallons. Cost of coal per ton. Annual consumption in million gallons. Cost of coal per ton. i to 5 $2. 14 150 to 175 $1.59 5 10 2-59 175 2OO 2.15 10 15 2.51 2OO 250 2.46 15 20 2.36 250 500 2-27 20 25 2.52 500 750 2.32 25 5 2.22 750 1000 2.09 50 75 2.36 1000 5000 2 .26 75 ioo 2.16 5000 10000 2.6 4 100 125 2 .02 10,000 and over 2.29 125 150 2.66 result should be reduced to a sliding scale of cost per 1000 gal- lons of water, for application as a tariff upon the water service 408 FRANCHISE. WATER RATES. DEPRECIATION. of individual consumers in proportion to the amount of water consumed. The matter of depreciation resulting from the deterioration of physical property should be considered in relation to plants under municipal ownership and administration as well as those under private ownership and control. Unless proper provision is made for the maintenance of the property under either kind of owner- ship and administration, that is to say, provision for the losses incident to physical deterioration, there must necessarily be a progressive shrinkage of value, for which there is no tangible equivalent. Provision of this character must come from some definite source, when the physical property subject to deteriora- tion is assembled into a mechanical unit for a definite purpose, as for the production and sale of a commodity. Evidently the income from the sale of that commodity must be the source from which is derived the revenue with which to operate and maintain the physical property. If it is necessary to expend money in addition to that expended in the construction of the physical property, in order to make a market for the commodity in such amount and at such a price as to secure an income suffi- cient to operate and maintain the physical property and pay interest upon the investment therein, the amount of money so expended is a cost of establishing the business. Income eventu- ally derived from the sale of the commodity which is in excess of that needed to support the physical property in the manner indicated and to pay interest upon the money expended in estab- lishing the business is an asset against which negotiable paper of some sort may be and usually is issued in a purely private and unrestricted undertaking in some definite amount, which possesses value in the commercial market of an amount depend- ing upon the interest or dividends which the excess income will support. Frequently a portion of this excess income is first set aside as a surplus fund available for emergency expenses or as a substitute for the capitalization represented by the negoti- able paper and the remainder only applied to dividends. In the case of a public-service corporation, depending upon a franchise for the right to construct and operate works for the FRANCHISE. WATER RATES. DEPRECIATION. 409 production and sale of a commodity at some fixed rate, the capi- talization of the excess income as before described is sometimes termed franchise value. However, under a limited franchise con- taining express provision of the grantor's right to purchase and an implied intention of purchase at some stated interval or at the expiration of the franchise, it is often asserted that securi- ties representing purely capitalized income should have but a limited circulation in the financial market at any time, as they may have no value at the expiration of the franchise or an indefinite value at a time of purchase before the expiration of the franchise. It is also maintained that the public as a grantor of a franchise receiving no compensation for the gift should not be expected much less required to buy back the franchise at the time of the purchase, particularly at the expiration of the period covered in the grant. Claim is also made, with regard to the rates under which water is dispensed as a commodity by a public water-service corporation, that they were never intended to accumulate more income than is necessary to pay operating expenses and to pro- vide a reasonable fund for interest upon and maintenance of the investment, and that any income in excess of this should be con- sidered the result of the use of an excessive water rate, and accord- ingly should be applied to the liquidation of the investment, or the water rates should be proportionately reduced. The fact is when water-works franchises were granted years ago little thought was expended upon matters of this kind, the municipality desired the water service, and private individuals were ready to accept the obligation of supplying municipalities and to speculate somewhat upon the venture. What income the water rates would return was largely speculative, aside from the fixed income of hydrant rent. The question of franchise value as applied to water-service corporations becomes there- fore a question of the moment and of the occasion, susceptible of consideration in some instances and of none in others, depending largely upon the terms of the franchise ordinance itself and the legality of and equity in claims of this character. It is perfectly evident that the proper support and main- tenance of the physical property is of first consideration and that there can be no consideration of franchise value whatever, 410 FRANCHISE. WATER RATES DEPRECIATION. assuming the validity of such a claim to be open to considera- tion, until adequate provision shall have been made from the income for the support and maintenance of physical property. It is clear that if a water-works property is appraised at a valuation based upon the cost of reproduction less depreciation, there should be more than presumptive evidence that the income has been sufficient to reimburse the seller for the losses which this method of valuation entails, as well as a fair interest upon the investment. Information regarding original cost and income and current expenses is not always available, and in the absence of proper and substantial information of this character approxi- mations only can be made, based upon general information of a similar character. Although only the depreciation resulting from deterioration of the physical property has been mentioned, the depreciation resulting from a gradual deterioration of service is also open to consideration. But a marked distinction should be made in the two types of depreciation. The former type of depreciation results solely from physical deterioration, the latter type relates to the earnings and represents depreciation of the business or "going value" of the water-works property. The one relates to elements entering the construction of the water- works, the other relates to elements of business management in dispensing the water service and in providing the necessary means for the proper dispensation of this service. While the deterioration of service may at times result from an incapacity of the physical property, still the measure of that deterioration can only be made through its depreciating effect upon the earnings resulting from the operation of the plant. In illustration of this principle a water-works plant which through the lapse of years develops an incapacity or deficiency in part or as a whole, which is mani- fest through imperfect or inadequate service, is subject to a charge upon its earnings over and above operating expenses of an amount which will pay interest upon and maintain the investment re- quired in reinforcing the deficient part or parts of the plant. The earnings are also similarly chargeable with an amount which will support properly the investment in and the operation of purification works needed to purify water from a source of FRANCHISE. WATER RATES. DEPRECIATION. 4* I supply which, though originally producing an acceptable and wholesome water, has through the lapse of years become polluted through unpreventable sources or influences, or water from a supply which originally required purification, but which is inade- quately purified through neglect to extend the purification works as needed, or through an effort to reduce operating expenses at the expense of the water service. The converse of this situation is also true. The earnings of a business which does not properly support the original investment, together with that needed from time to time to reinforce the plant and to maintain an efficient service, should receive in them- selves reinforcement through an increase, if necessary,, of the schedule of charges for the water service. Considerations of this character are particularly necessary when, for any reason, an effort is made to reach a commercial value of a property through a capitalization of net earnings. A neglect to observe them is particularly liable to result in over- valuation of a property appraised at or near the expiration of a limited franchise, and may in other instances result in under- valuation, when the actuating policy of the management is to reinforce and build in anticipation of future requirements. Attempts are made to harmonize both types of deterioration by basing estimates of depreciation upon the serviceable life of the materials of construction as assembled in units rather than upon the actual physical life of the materials, independent of the useful life of the respective units into which they may be assembled. The serviceable life is shorter than the physical life in amounts depending upon the actual conditions and require- ments of service. There are three methods of computing depreciation which have had more or less extended application each method recog- nizing progressive physical deterioration. The first method assumes a certain annual rate of depreciation, and computes the annual depreciation for each year upon the original investment. For instance, assume a rate of depreciation of 2 per cent per annum which is equivalent to an assumed physical life of fifty years then the annual depreciation for each $1000 of investment by this method becomes $20 and for twenty years is 8400. 412 FRANCHISE. WATER RATES. DEPRECIATION. This method of computation takes no account whatever of the interest earning capacity of the $20 annuities for each $1000 of investment during the interval for which the deprecia- tion is estimated. If these $20 annual payments were con- sidered as an annuity, drawing interest at the rate of 2 per cent per annum, it would amount to $1692 for each $1000 of the orig- inal investment at the end of fifty years. Accordingly an appor- tionment annually of $20 per $1000 investment from the gross earnings, and likewise the water rate which support such an annual apportionment of funds, becomes excessive. If depreciation is estimated on this basis, it should be con- sidered that the annual payments are immediately applied as partial payments on the original investment and the interest- bearing portion thereof accordingly reduced. For instance, assume the $1000 valuation upon which the depreciation has been computed to draw 6 per cent interest, then the increment by which the annual, interest would be decreased, assuming the $20 annual payments to be immediately applied to payments on the original principal, is 6 per cent of $20 or $1.20, and if this latter amount should be considered as an annuity, it would have to be invested at about 8 per cent to amount to the differ- ence between the $1692, the amount of the $20 annuity, and $1000, the original investment, or at a proportionately higher rate of interest for a 3 per cent investment, etc. Evidently this method calls for too heavy a rate of depreciation, and for an application of the annual payments not usually made. The second method of computing depreciation assumes some rate of depreciation, as in the preceding case, but computes the depreciation on the principal of the preceding year instead of on the original investment continuously. For instance, the assumed rate of depreciation of 2 per cent a year would run as follows per 1000 investment: Unpaid principal. End of first year $1000 . oo X o . 02 = $20 . oo $980 . oo " " second 980.00X0.02= 19.60 960.40 third 960.40X0.02= 19.21 941.19 twentieth " 681.23X0.02= 13.62 667.61 fiftieth 371.60X0.02= 7.43 364.17 private, 401, 402, 404; municipal, 402 Water-works force account, 365 Water-works system, benefits from, 37i Weir method of measurement, 193 Weirs, 118, 119, 149; elevation of, 129 ff. ; flow of water over, 226 Well, deep, water from, 7 ff. ; single open, 48 ; substitute for, 56 ; close, 72; water, filtered, 112 Well-strainers, 59; length of, 65; area of openings, 66, 67 ; form of, an important consideration, 68 ff. Well system, layout of, 83; strainer capacity, 83; pipe resistance, 83 Well water, from deep wells, 7 ff. ; filtered, 112 Wells, light, 300 INDEX. 429 Weser, water of, 168; United States rivers comparable with, 169 Wholesomeness and clearness, 15 Winslow electrical indicating and recording apparatus, 229 Winter treatment of river-water, 156, 157 Wrought iron, pipes of, 254 Yarn, cost of, 247 Yarning-iron, 237 Yielding capacity, factors for determination of, 40, 41 ; manent, of sand-bed, 48 the per- SHORT-TITLE CATALOGUE OF THE PUBLICATIONS OF JOHN WILEY & SONS, NEW YORK. LONDON: CHAPMAN & HALL, LIMITED. ARRANGED UNDER SUBJECTS. Descriptive circulars sent on application. Books marked with an asterisk (*) are sold at net prices only. All books are bound in cloth unless otherwise stated. AGRICULTURE. Armsby's Manual of Cattle-feeding izmo, Si 75 Principles of Animal Nutrition 8vo, 4 oo Budd and Hansen's American Horticultural Manual: Part I. Propagation, Culture, and Improvement i2mo, i 50 Part II. Systematic Pomology 12010, i 50 Downing's Fruits and Fruit-trees of America 8vo, 5 oo Elliott's Engineering for Land Drainage i2mo, i 50 Practical Farm Drainage 12010, i oo Graves's Forest Mensuration 8vo, 4 oo Green's Principles of American Forestry i2mo, i 50 Grotenfelt's Principles of Modern Dairy Practice. (Wo 11.) i2mo, 2 oo Herrick's Denatured or Industrial Alcohol 8vo, 4 oo Kemp's Landscape Gardening i2mo, 2 50 Maynard's Landscape Gardening as Applied to Home Decoration i2mo, i 50 * McKay and Larsen's Principles and Practice of Butter-making 8vo, i 50 Sanderson's Insects Injurious to Staple Crops i2mo, i 50 *Schwarz's Longleaf Pine in Virgin Forest iamo, i 25 Stockbridge's Rocks and Soils 8vo, 2 50 Winton's Microscopy of Vegetable Foods 8vo, 7 5<> Woll's Handbook for Farmers and Dairymen 1 6mo, i 50 ARCHITECTURE. Baldwin's Steam Heating for Buildings I2mo, 253 Bashore's Sanitation of a Country House i2mo, i oo Berg's Buildings and Structures of American Railroads 4to, 5 oo Birkmire's Planning and Construction of American Theatres 8vo, 3 oo Architectural Iron and Steel 8vo, 3 50 Compound Riveted Girders as Applied in Buildings 8vo, 2 oo Planning and Construction of High Office Buildings 8vo, 3 50 Skeleton Construction in Buildings 8vo, 3 oo Brigg's Modern American School Buildings 8vo, 4 oo 1 Carpenter's Heating and Ventilating of Buildings Svo, 4 oo Freitag's Architectural Engineering Svo, 3 50 Fireproofing of Steel Buildings Svo, 2 50 French and Ives's Stereotomy Svo, 2 50 Gerhard's Guide to Sanitary House-inspection i6mo, i oo Theatre Fires and Panics i2mo, i 50 *Greene's Structural Mechanics Svo, 2 50 Holly's Carpenters' and Joiners' Handbook iSmo, 75 Johnson's Statics by Algebraic and Graphic Methods Svo, 2 oo Kidder's Architects' and Builders' Pocket-book. Rewritten Edition. i6mo,mor., 5 oo Merrill's Stones for Building and Decoration Svo, 5 oo Non-metallic Minerals: Their Occurrence and Uses Svo, 4 oo Monckton's Stair-building 4to, 4 oo Patton's Practical Treatise on Foundations Svo, 5 oo Peabody's Naval Architecture Svo, 7 50 Rice's Concrete-block Manufacture Svo, 2 oo Richey's Handbook for Superintendents of Construction i6mo, mor., 4 oo * Building Mechanics' Ready Reference Book. Carpenters' and Wood- workers' Edition i6mo, morocco, i 50 Sabin's Industrial and Artistic Technology of Paints and Varnish Svo, 3 oo Siebert and Biggin's Modern Stone-cutting and Masonry Svo, i 50 Snow's Principal Species of Wood Svo, 3 50 Sondericker's Graphic Statics with Applications to Trusses, Beams, and Arches. Svo, 2 oo Towne's Locks and Builders' Hardware iSmo, morocco, 3 oo Wait's Engineering and Architectural Jurisprudence Svo, 6 oo Sheep, 6 50 Law of Operations Preliminary to Construction in Engineering and Archi- tecture Svo, 5 oo Sheep, 5 50 Law of Contracts Svo, 3 oo Wood's Rustless Coatings: Corrosion and Electrolysis of Iron and Steel. .Svo, 4 oo Worcester and Atkinson's Small Hospitals, Establishment and Maintenance, Suggestions for Hospital Architecture, with Plans for a Small Hospital. i2mo, i 25 The World's Columbian Exposition of 1893 Large 4to, i oo ARMY AND NAVY. Bernadou's Smokeless Powder, Nitro-cellulose, and the Theory of the Cellulose Molecule i2mo, 2 50 Chase's Screw Propellers and Marine Propulsion Svo, 3 oo Cloke's Gunner's Examiner 8vo, i 50 Craig's Azimuth 4 t o , 3 50 Crehore and Squier's Polarizing Photo-chronograph Svo, 3 oo * Davis's Elements of Law .Svo, 2 50 * Treatise on the Military Law of United States Svo, 7 oo Sheep, 7 50 De Brack's Cavalry Outposts Duties. (Carr.) 24mo, morocco, 2 oo Dietz's Soldier's First Aid Handbook i6mo, morocco, i 25 * Dudley's Military Law and the Procedure of Courts-martial. . . Large i2mo, 2 50 Durand's Resistance and Propulsion of Ships 8vo, 5 oo * Dyer's Handbook of Light Artillery i2mo, 3 oo Eissler's Modern High Explosives 8vo, 4 oo * Fiebeger's Text-book on Field Fortification Small Svo, 2 oo Hamilton's The Gunner's Catechism iSmo, i oo * Hoff's Elementary Naval Tactics 8vo, i 50 2 Ingalls's Handbook of Problems in Direct Fire 8vo, 4 oo * Ballistic Tables 8vo, i 50 * Lyons's Treatise on Electromagnetic Phenomena. Vols. I. and II. .8vo, each, 6 oo * Mahan's Permanent Fortifications. (Mercur.) 8vo, half morocco, 7 50 Manual for Courts-martial i6mo, morocco, I 50 * Mercur's Attack of Fortified Places i2mo, 2 oo * Elements of the Art of War 8vo, 4 oo Metcalf's Cost of Manufactures And the Administration of Workshops. .8vo, 5 oo * Ordnance and Gunnery. 2 vols i2mo, 5 oo Murray's Infantry Drill Regulations i8mo, paper, 10 Nixon's Adjutants' Manual. 24mo, i oo Peabody's Naval Architecture 8vo, 7 50 * Phelps's Practical Marine Surveying 8vo, 2 50 Powell's Army Officer's Examiner i2mo, 4 oo Sharpe's Art of Subsisting Armies in War 1 8mo, morocco, i 50 * Tupes and Poole's Manual of Bayonet Exercises and Musketry Fencing. 24mo, leather, 50 * Walke's Lectures on Explosives 8vo, 4 oo Weaver's Military Explosives 8vo, 3 oo * Wheeler's Siege Operations and Military Mining 8vo, 2 oo Winthrop's Abridgment of Military Law I2mo, 2 50 Woodhull's Notes on Military Hygiene i6mo, i 50 Young's Simple Elements of Navigation i6mo, morocco, 2 oo ASSAYING. Fletcher's Practical Instructions in Quantitative Assaying with the Blowpipe. i2mo, morocco, i 50 Furman's Manual of Practical Assaying 8vo, 3 oo Lodge's Notes on Assaying and Metallurgical Laboratory Experiments. . . .8vo, 3 oo Low's Technical Methods of Ore Analysis 8vo, 3 oo Miller's Manual of Assaying I2mo, i oo Cyanide Process i2mo, i oo Minet's Production of Aluminum and its Industrial Use. (Waldo.) i2mo, 2 50 O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 oo Ricketts and Miller's Notes on Assaying 8vo, 3 oo Robine and Lenglen's Cyanide Industry. (Le Clerc.) 8vo, 4 oo Ulke's Modern Electrolytic Copper Refining 8vo, 3 oo Wilson's Cyanide Processes I2mo, i 50 Chlorination Process I2mo, i 50 ASTRONOMY. Comstock's Field Astronomy for Engineers 8vo, 2 50 Craig's Azimuth 4to, 3 50 Crandall's Text-book on Geodesy and Least Squares 8vo, 3 oo Doolittle's Treatise on Practical Astronomy 8vo, 4 oo Gore's Elements of Geodesy 8vo, 2 50 Hayford's Text-book of Geodetic Astronomy 8vo, 3 oo Merriman's Elements of Precise Surveying and Geodesy 8vo, 2 50 * Michie and Harlow's Practical Astronomy. . .* 8vo, 3 oo * White's Elements of Theoretical and Descriptive Astronomy i2mo oo BOTANY. Davenport's Statistical Me'.hDds, with Special Reference to Biological Variation. i6mo, morocco, i 25 Thome* and Bennett's Structural and Physiological Botany i6mo, 2 25 Westermaier's Compendium of General Botany. (Schneider.) 8vo, 2 oo 3 CHEMISTRY. * Abegg's Theory of Electrolytic Dissociation. (Von Ende.) i2mo, i 25 Adriance's Laboratory Calculations and Specific Gravity Tables i2mo. i 25 Alexeyeff's General Principles of Organic Synthesis. 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(Chemical and Bacteriological. ) i2mo, i 25 Matthew's The Textile Fibres. 2d Edition, Rewritten 8vo, 400 Meyer's Determination of Radicles in Carbon Compounds. (Tingle.). .i2mo, i oo' Miller's Manual of Assaying i2mo, i ocr Cyanide Process i2mo, i oo Minet's Production of Aluminum and its Industrial Use. (Waldo.). . . . i2mo, 2 50 Mixter's Elementary Text-book of Chemistry I2mo, I 50 Morgan's An Outline of the Theory of Solutions and its Results i2mo, i oo Elements of Physical Chemistry I2mo, 3 oo * Physical Chemistry for Electrical Engineers i2mo, S^oo Morse's Calculations used in Cane-sugar Factories i6mo, morocco, i 50 * Muir's History of Chemical Theories and Laws 8vo, 4 oo Mulliken's General Method for the Identification of Pure Organic Compounds. Vol. I Large 8vo, 5 oo O'Brine's Laboratory Guide in Chemical Analysis 8vo, oo O'Driscoll's Notes on the Treatment of Gold Ores , 8vo, oo Ostwald's Conversations on Chemistry. Part One. (Ramsey.) I2mo, 50 " " Part Two. (TurnbulL) I2mo, oo * Pauli's Physical Chemistry in the Service of Medicine. (Fischer.) .... i2mo, 25 * Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests. 8vo, paper, 50 Pictet's The Alkaloids and their Chemical Constitution. (Biddle.) 8vo, 5 oo Pinner's Introduction to Organic Chemistry. (Austen.) I2mo. i 50 Poole's Calorific Power of Fuels 8vo, 3 oo Prescott and Winslow's Elements of Water Bacteriology, with Special Refer- ence to Sanitary Water Analysis I2mo, I 25 * Reisig's Guide to Piece-dyeing 8vo, 25 oo Richards and Woodman's Air, Water, and Food from a Sanitary Standpoint..8vo, 2 oo Ricketts and Russell's Skeleton Notes upon Inorganic Chemistry. (Part I. Non-metallic Elements.) 8vo, morocco, 75 Ricketts and Miller's Notes on Assaying 8vo, 3 oo Rideal's Sewage and the Bacterial Purification of Sewage 8vo, 4 oo Disinfection and the Preservation of Food 8vo, 4 oo Riggs's Elementary Manual for the Chemical Laboratory 8vo, i 25 Robine and Lenglen's Cyanide Industry. (Le Clerc.) 8vo, 4 oo Ruddiman's Incompatibilities in Prescriptions 8vo, 2 oo * Whys in Pharmacy . I2mo, i oo Sabin's Industrial and Artistic Technology of Paints and Varnish 8vo, 3 oo Salkowski's Physiological and Pathological Chemistry. (Orndorff.) 8vo, 2 50 Schimpf's Text-book of Volumetric Analysis I2mo, 2 50 Essentials of Volumetric Analysis I2mo, i 25 * Qualitative Chemical Analysis 8vo, i 25 Smith's Lecture Notes on Chemistry for Dental Students 8vo, 2 50 Spencer's Handbook for Chemists of Beet-sugar Houses i6mo, morocco, 3 oo Handbook for Cane Sugar Manufacturers i6mo, morocco, 3 oo Stockbridge's Rocks and Soils 8vo, 2 50 * Tollman's Elementary Lessons in Heat 8vo, i 50 * Descriptive General Chemistry 8vo, 3 oo Treadwell's Qualitative Analysis. (Hall.) 8vo, 3 oo Quantitative Analysis. (Hall.) 8vo, 4 oo Turneaure and Russell's Public Water-supplies 8vo, 5 oo. 5 Van Deventer's Physical Chemistry for Beginners. (Boltwood.) ..... .i2mo, i 50 * Walke's Lectures on Explosives 8vo, 4 oo Ware's Beet-sugar Manufacture and Refining. Vol. I Small 8vo, 4 oo Vol.11 SmallSvo, 500 Washington's Manual of the Chemical Analysis of Rocks. . 8vo, 2 oo Weaver's Military Explosives 8vo, 3 oo Wehrenfennig's Analysis and Softening of Boiler Feed- Water 8vo, 4 oo Wells's Laboratory Guide in Qualitative Chemical Analysis 8vo, i 50 Short Course in Inorganic Qualitative Chemical Analysis for Engineering Students 121110, i 50 Text-book of Chemical Arithmetic i2mo, i 25 Whipple's Microscopy of Drinking-water 8vo, 3 50 Wilson's Cyanide Processes I2mo, i 50 Chlorination Process i2rno, i 50 Winton's Microscopy of Vegetable Foods 8vo, 7 50 Wulling's Elementary Course in Inorganic, Pharmaceutical, and Medical Chemistry I2mo, 2 oo CIVIL ENGINEERING. BRIDGES AND ROOFS, HYDRAULICS. MATERIALS OF ENGINEERING. RAILWAY ENGINEERING. Baker's Engineers' Surveying Instruments i2mo, 3 oo Bixby's Graphical Computing Table Paper 19^X24! inches. 25 Breed and Hosmer's Principles and Practice of Surveying 8vo, 3 oo * Burr's Ancient and Modern Engineering and the Isthmian Canal 8vo, 3 50 Comstock's Field Astronomy for Engineers 8vo, 2 50 Crandall's Text-book on Geodesy and Least Squares 8vo, 3 oo Davis's Elevation and Stadia Tables 8vo, i oo Elliott's Engineering for Land Drainage i2mo, i 50 Practical Farm Drainage i2mo, i oo *Fiebeger's Treatise on Civil Engineering 8vo, 5 oo Flemer's Phototopographic Methods and Instruments 8vo, 5 oo Folwell's Sewerage. (Designing and Maintenance.) 8vo, 3 oo Freitag's Architectural Engineering. 2d Edition, Rewritten 8vo, 3 So French and Ives's Stereotomy 8vo, 2 50 Goodhue's Municipal Improvements i2mo, i 50 Gore's Elements of Geodesy 8vo, 2 50 Hayford's Text-book of Geodetic Astronomy 8vo, 3 oo Bering's Ready Reference Tables (Conversion Factors) i6mo, morocco, 2 50 Howe's Retaining Walls for Earth i2mo, i 25 * Ives's Adjustments of the Engineer's Transit and Level i6mo, Bds. 25 Ives and Hilts's Problems in Surveying i6mo, morocco, i 50 Johnson's (J. B.) Theory and Practice of Surveying Small 8vo, 4 oo Johnson's (L. J.) Statics by Algebraic and Graphic Methods 8vo, 2 oo Laplace's Philosophical Essay on Probabilities. (Truscott and Emory.). i2mo, 2 oo Mahan's Treatise on Civil Engineering. (1873.) (Wood.) 8vo, 5 oo * Descriptive Geometry 8vo, i 50 Merriman's Elements of Precise Surveying and Geodesy 8vo, 2 50 Merriman and Brooks's Handbook for Surveyors i6mo, morocco, 2 oo Nugent's Plane Surveying 8vo, 3 50 Ogden's Sewer Design i2mo, 2 oo Parsons's Disposal of Municipal Refuse 8vo, 2 oo Patton's Treatise on Civil Engineering 8vo half leather, 7 50 Reed's Topographical Drawing and Sketching 4to, 5 oo Rideal's Sewage and the Bacterial Purification of Sewage 8vo, 4 oo Siebert and Biggin's Modern Stone-cutting and Masonry 8vo, i 50 6 Smith's Manual 01 Topographical Drawing. (McMillan.) 8vo, 2 50 Sondericker's Graphic Statics, with Applications to Trusses, Beams, and Arches. 8vo, 2 oo Taylor and Thompson's Treatise on Concrete, Plain and Reinforced 8vo, 5 oo * Trautwine's Civil Engineer's Pocket-book i6mo, morocco, 5 oo Venable's Garbage Crematories in America 8vo, 2 oo Wait's Engineering and Architectural Jurisprudence 8vo 6 oo Sheep, 6 50 Law of Operations Preliminary to Construction in Engineering and Archi- tecture 8vo, 5 oo Sheep, 5 50 Law of Contracts 8vo, 3 oo Warren's Stereotomy Problems in Stone-cutting 8vo, 2 50 Webb's Problems in the Use and Adjustment of Engineering Instruments. i6mo, morocco, i .25 Wilson's Topographic Surveying 8vo, 3 50 BRIDGES AND ROOFS. Boiler's Practical Treatise on the Construction of Iron Highway Bridges. .8vo, 2 oo * Thames River Bridge 4to, paper, 5 oo Burr's Course on the Stresses in Bridges and Roof Trusses, Arched Ribs, and Suspension Bridges 8vo* 3 50 Burr and Falk's Influence Lines for Bridge and Roof Computations 8vo, 3 oo Design and Construction of Metallic Bridges 8vo 5 oo Du Bois's Mechanics of Engineering. Vol. II Small 4to, 10 oo Foster's Treatise on Wooden Trestle Bridges. . 4to, 5 oo Fowler's Ordinary Foundations 8vo, 3 50 Greene's Roof Trusses 8vo, i 25 Bridge Trusses 8vo, 2 50 Arches in Wood, Iron, and Stone 8vo 2 50 Howe's Treatise on Arches 8vo, 4 oo Design of Simple Roof- trusses in Wood and Steel , 8vo, 2 oo Symmetrical Masonry Arches 8vo, 2 50 Johnson, Bryan, and Turneaure's Theory and Practice in the Designing of Modern Framed Structures Small 4to, 10 oo Merrimin and Jacoby's Text-book on Roofs and Bridges : Fori L Stresses in Simple Trusses 8vo, 2 50 Part JL Graphic Statics 8vo, 2 50 Fart ffl. Bridge Design 8vo, 2 50 Part TV. Higher Structures 8vo, 2 50 Morison's Memphis Bridge 4to, 10 oo Waddell's De Pontibus, a Pocket-book for Bridge Engineers. . i6mo, morocco, 2 oo * Specifications for Steel Bridges i2mo, 50 Wright's Designing of Draw-spans. Two parts in one volume 8vo, 3 5<> HYDRAULICS. Barnes's Ice Formation 8vo 3 oo Bazin's Experiments upon the Contraction of the Liquid Vein Issuing from an Orifice. (Trautwine.) 8vo - 2 Bovey's Treatise on Hydraulics 8vo 5 o Church's Mechanics of Engineering 8vo, 6 Diagrams of Mean Velocity of Water in Open Channels paper, i 5 Hydraulic Motors 8vo 2 Coffin's Graphical Solution of Hydrr.ulic Problems i6mo, morocco, 2 Flather's Dynamometers, and the Measurement of Power xamo, 3 oo 7 FolwelTs Water-supply Engineering 8vo, 4 oo FrizelTs Water-power 8vo, 5 oo Fuertes's Water and Public Health i2mo, i 50 Water-filtration Works. i2mo, 2 50 Ganguillet and Kutter's General Formula for the Uniform Flow of Water in Rivers and Other Channels. (Bering and Trautwine.) 8vo, 4 oo Hazen's Filtration of Public Water-supply 8vo, 3 oo Hazlehurst's Towers and Tanks for Water-works 8vo, 2 50 Herschel's 115 Experiments on the Carrying Capacity of Large, Riveted, Metal Conduits 8vo, 2 oo Mason's Water-supply. (Considered Principally from a Sanitary Standpoint.) 8vo, 4 oo Merriman's Treatise on Hydraulics 8vo, 5 oo * Michie's Elements of Analytical Mechanics 8vo, 4 oo Schuyler's Reservoirs for Irrigation, Water-power, and Domestic Water- supply Large 8vo, 5 oo * Thomas and Watt's Improvement of Rivers 4to, 6 oo Turneaure and Russell's Public Water-supplies 8vo, 5 oo Wegmann's Design and Construction of Dams 4to, 5 oo Water-supply of the City of New York from 1658 to 1895 4to, 10 oo Whipple's Value of Pure Water Large i2mo, i oo Williams and Hazen's Hydraulic Tables 8vo, i 50 Wilson's Irrigation Engineering Small 8vo, 4 oo Wolff's Windmill as a Prime Mover 8vo, 3 oo Wood's Turbines 8vo, 2 50 Elements of Analytical Mechanics . . .8vo, 3 oo MATERIALS OF ENGINEERING. Baker's Treatise on Masonry Construction 8vo, 5 oo Roads and Pavements 8vo, 5 oo Black's United States Public Works Oblong 4to, 5 oo * Bovey's Strength of Materials and Theory of Structures 8vo, 7 50 Burr's Elasticity and Resistance of the Materials of Engineering 8vo, 7 50 Byrne's Highway Construction 8vo, 5 oo Inspection of the Materials and Workmanship Employed in Construction. i6mo, 3 oo Church's Mechanics of Engineering 8vo, 6 oo Du Bois's Mechanics-of Engineering. Vol. I. Small 4to, 7 50 *Eckel's Cements, Limes, and Plasters 8vo, 6 oo Johnson's Materials of Construction Large 8vo, 6 oo Fowler's Ordinary Foundations 8vo, 3 50 Graves's Forest Mensuration 8vo, 4 oo * Greene's Structural Mechanics 8vo, 2 50 Keep's Cast Iron 8vo, 2 50 Lanza's Applied Mechanics 8vo, 7 50 Marten's Handbook on Testing Materials. (Henning.) 2 vols 8vo, 7 50 Maurer's Technical Mechanics 8vo, 4 oo Merrill's Stones for Building and Decoration 8vo, 5 oo Merriman's Mechanics of Materials 8vo, 5 oo * Strength of Materials i2mo, i oo Metcalf's Steel. A Manual for Steel-users i2mo, 2 oo Patton's Practical Treatise on Foundations 8vo, 5 oo Richardson's Modern Asphalt Pavements 8vo, 3 oo Richey's Handbook for Superintendents of Construction i6mo, mor., 4 oo * Ries's Clays: Their Occurrence, Properties, and Uses 8vo, 5 oo Rockwell's Roads and Pavements in France i2mo, i 25 8 Sabin's Industrial and Artistic Technology of Paints acd Varnish 8vo, 3 oo *Schwarz's Longleaf Pine in Virgin Forest .. ino, i 25 Smith's Materials of Machines izmo, i oo Snow's Principal Species of Wood 8vo, 3 50 Spalding's Hydraulic Cement izmo, 2 oo Text-book on Roads and Pavements I2mo, 2 oo Taylor and Thompson's Treatise on Concrete, Plain and Reinforced 8vo, 5 oo Thurston's Materials of Engineering. 3 Parts 8vo, 8 oo Part I. Non-metallic Materials of Engineering and Metallurgy 8vo, 2 oo Part n. Iron and SteeL 8vo, 3 50 Part in. A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo, 2 50 Tillson's Street Pavements and Paving Materials 8vo, 4 oo WaddelPs De Pontibus. (A Pocket-book for Bridge Engineers.). . i6mo, mor., 2 oo * Specifications for Steel Bridges i2mo, 50 Wood's (De V.) Treatise on the Resistance of Materials, and an Appendix on the Preservation of Timber 8vo, 2 oo Wood's (De V.) Elements of Analytical Mechanics 8vo, 3 oo Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and SteeL 8vo, 4 oo RAILWAY ENGINEERING. Andrew's Handbook for Street Railway Engineers 3x5 inches, morocco, I 25 Berg's Buildings and Structures of American Railroads 4to, 5 oo Brook's Handbook of Street Railroad Location. i6mo, morocco, I 50 Butt's Civil Engineer's Field-book i6mo, morocco, 2 50 Crandall's Transition Curve i6mo, morocco, i 50 Railway and Other Earthwork Tables 8vo, I 50 Dawson's "Engineering" and Electric Traction Pocket-book. . i6mo, morocco, 5 oo Dredge's History of the Pennsylvania Railroad: (1879) Paper, 5 oo Fisher's Table of Cubic Yards Cardboard, 25 Godwin's Railroad Engineers' Field-book and Explorers' Guide. . . i6mo, mor., 2 50 Hudson's Tables for Calculating the Cubic Contents of Excavations and Em- bankments 8vo, i oo Molitor and Beard's Manual for Resident Engineers i6mo, i oo Nagle's Field Manual for Railroad Engineers i6mo, morocco, 3 oo Philbrick's Field Manual for Engineers i6mo, morocco, 3 oo Searles's Field Engineering i6mo, morocco, 3 oo Railroad SpiraL i6mo, morocco, i 50 Taylor's Prismoidal Formulas and Earthwork 8vo, i 50 * Trautwine's Method of Calculating the Cube Contents of Excavations and Embankments by the Aid of Diagrams 8vo, 2 oo The Field Practice of Laying Out Circular Curves for Railroads. i2mo, morocco, 2 50 Cross-section Sheet Paper, 25 Webb's Railroad Construction i6mo, morocco, 5 oo Economics of Railroad Construction Large i2mo, 2 50 Wellington's Economic Theory of the Location of Railways Small 8vo, 5 oo DRAWING. Barr's Kinematics of Machinery 8vo, 2 50 * Bartlett's Mechanical Drawing 8vo, 3 oo * " " " Abridged Ed 8vo, 150 Coolidge's Manual of Drawing 8vo, paper, i oo 9 Coolidge and Freeman's Elements of General Drafting for Mechanical Engi- neers Obkmg 4to, 2 50 Durley's Kinematics of Machines 8vo, 4 oo Emch's Introduction to Projective Geometry and its Applications 8vo, 2 50 Hill's Text-book on Shades and Shadows, and Perspective SYO, 2 oo Jamison's Elements of Mechanical Drawing 8vo, 2 50 Advanced Mechanical Drawing 8vo, 2 oo Jones's Machine Design: Part I. Kinematics of Machinery 8vo, i 50 Part II. Form, Strength, and Proportions of Parts 8vo, 3 oo MacCord's Elements of Descriptive Geometry 8vo, 3 oo Kinematics ; or, Practical Mechanism 8vo, 5 oo Mechanical Drawing 4to, 4 oo Velocity Diagrams 8vo, i 50 MacLeod's Descriptive Geometry Small 8vo, i 50 * Mahan's Descriptive Geometry and Stone-cutting: 8vo, i 50 Industrial Drawing. (Thompson.) 8vo, 3 50 Moyer's Descriptive Geometry 8vo, 2 oo Reed's Topographical Drawing and Sketching 4to, 5 oo Reid's Course in Mechanical Drawing 8vo, 2 oo Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, 3 oo Robinson's Principles of Mechanism 8vo, 3 oo Schwamb and Merrill's Elements of Mechanism 8vo, 3 oo Smith's (R. S.) Manual of Topographical Drawing. (McMillan.) 8vo, 2 50 Smith (A. W.) and Marx's Machine Design 8vo, 3 oo * Titsworth's Elements of Mechanical Drawing Oblong 8vo, i 25 Warren's Elements of Plane and Solid Free-hand Geometrical Drawing. i2mo, i oo Drafting Instruments and Operations i2mo, i 25 Manual of Elementary Projection Drawing i2mo, i 50 Manual of Elementary Problems in the Linear Perspective of Form and Shadow i2tno, i oo Plane Problems in Elementary Geometry i2mo, i 25 Primary Geometry. I2mo, 75 Elements of Descriptive Geometry, Shadows, and Perspective 8vo, 3 50 General Problems of Shades and Shadows 8vo, 3 oo Elements of Machine Construction and Drawing 8vo, 7 50 Problems, Theorems, and Examples in Descriptive Geometry 8vo, 2 50 Weisbach's Kinematics and Power of Transmission. (Hermann and Klein.) 8vo, 5 oo Whelpley's Practical Instruction in the Art of Letter Engraving. ..... .i2mo, 2 oo Wilson's (H. M.) Topographic Surveying 8vo, 3 50 Wilson's (V. T.) Free-hand Perspective 8vo f 2 50 Wilson's (V. T.) Free-hand Lettering 8vo, i oo Woolf's Elementary Course in Descriptive Geometry Large 8vo, 3 oo ELECTRICITY AND PHYSICS. * Abegg's Theory of Electrolytic Dissociation. (Von Ende.) 12010, i 25 Anthony and Brackett's Text-book of Physics. (Magie.) Small 8vo 3 oo Anthony's Lecture-notes on the Theory of Electrical Measurements. . . . 12 mo, i oo Benjamin's History of Electricity 8vo, 3 oo Voltaic Cell 8vo, 3 oo Classen's Quantitative Chemical Analysis by Electrolysis. (Boltwood.).8vo, 3 oo * Collins's Manual of Wireless Telegraphy i2mo, i 50 Morocco, 2 oo Crehore and Squier's Polarizing Photo-chronograph 8ro, 3 oo * Danneel's Electrochemistry. (Merriam.) i2mo, i 25 Dawson's "Engineering" and Electric Traction Pocket-book. i6mo, morocco, 5 oo 10 Dolezalek's Theory of the Lead Accumulator (Storage Battery). (Von Ende.) I2mo, 2 50 Duhem's Thermodynamics and Chemistry. (Burgess.) 8vo, 4 oo Flather's Dynamometers, and the Measurement of Power. xarno, 3 oo Gilbert's De Magnete. (Mottelay.) 8vo, 2 50 Hanchett's Alternating Currents Explained I2mo, i oo Bering's Ready Reference Tables (Conversion Factors) i6mo, morocco, 2 50 Holman's Precision of Measurements 8vo, 2 OO Telescopic Mirror-scale Method, Adjustments, and Tests. . . .Large 8vo, 75 Kinzbrunner's Testing of Continuous-current Machines ' 8vo, 2 oo Landauer's Spectrum Analysis. (Tingle.) 8vo, 3 oo Le Chateliers High-temperature Measurements. (Boudouard Burgess.) i2mo, 3 oo Lob's Electrochemistry of Organic Compounds. (Lorenz.) 8vo, 3 oo * Lyons'? Treatise on Electromagnetic Phenomena. Vols. I. and II. 8vo, each, 6 oo * Michie's Elements of Wave Motion Relating to Sound and Light 8vo, 4 oo Niaudefs Elementary Treatise on Electric Batteries. (Fishback.) i2mo, 2 50 * Parshall and Hobart's Electric Machine Design 4to, half morocco, 12 50 Reagan's Locomotives: Simple, Compound, and Electric. New Edition. Large 12 mo, 3 50 * Rosenberg's Electrical Engineering. (Haldane Gee Kinzbrunner.). . .8vo, 2 oo Ryan, Norris, and Hoxie's Electrical Machinery. VoL 1 8vo, 2 50 Thurston's Stationary Steam-engines 8vo, 2 50 * Tillman's Elementary Lessons in Heat 8vo, i 50 Tory and Pitcher's Manual of Laboratory Physics Small 8vo, 2 oo Ulke's Modern Electrolytic Copper Refining 8vo, 3 oo LAW. * Davis's Elements of Law 8vo, 2 50 * Treatise on the Military Law of United States 8vo, 7 oo * Sheep, 7 So * Dudley's Military Law and the Procedure cf Courts-martial . . . .Large i2mo, 2 50 Manual for Courts-martial i6mo, morocco, i 50 Wait's Engineering and Architectural Jurisprudence 8vo, 6 oo Sheep, 6 50 Law of Operations Preliminary to Construction in Engineering and Archi- tecture 8vo 5 oo Sheep, 5 50 Law of Contracts 8vo, 3 oo Winthrop's Abridgment of Military Law I2mo, 2 50 MANUFACTURES. Bernadou's Smokeless Powder Nitro-cellulose and Theory of the Cellulose Molecule i2mo, 2 50 Bolland's Iron Founder i2mo, 2 50 The Iron Founder," Supplement I2mo, 2 50 Encyclopedia of Founding and Dictionary of Foundry Terms Used in the Practice of Moulding i2mo, 3 oo * Claassen's Beet-sugar Manufacture. (Hall and Rolfe.) 8vo, 3 oo * Eckel's Cements, Limes, and Plasters 8vo, 6 oo Eissler's Modern High Explosives 8vo, 4 oo Effront's Enzymes and their Applications. (Prescott.) 8vo, 3 oo Fitzgerald's Boston Machinist i2mo, i oo 'Ford's Boiler Making for Boiler Makers i8mo, i oo Herrick's Denatured or Industrial Alcohol 8vo, 400 Hopkin's Oil-chemists' Handbook 8vo, 3 oo Keep's Cast Iron 8v, 2 50 11 Leach's The Inspection and Analysis of Food with Special Reference to State Control. ' Large 8vo, 7 50 * McKay and Larsen's Principles and Practice of Butter-making 8vo, i 50 Matthews's The Textile Fibres, yd Edition, Rewritten 8vo, 4 oo Metcalf's Steel. 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Kinematics of Machinery 8vo, i 50 Part n. Form, Strength, and Proportions of Parts 8vo, 3 oo Kent's Mechanical Engineers' Pocket-book i6mo, morocco, 5 oo Kerr's Power and Power Transmission 8vo, 2 oo Leonard's Machine Shop, Tools, and Methods 8vo, 4 oo * Lorenz's Modern Refrigerating Machinery. (Pope, Haven, and Dean.) . . 8vo, 4 oo MacCord's Kinematics; or, Practical Mechanism 8vo, 5 oo Mechanical Drawing 4to, 4 oo Velocity Diagrams. 8vo, i 50 13 MacFarland's Standard Reduction Factors for Gases 8vo, i 50 Mahan's Industrial Drawing. (Thompson.) 8vo, 3 50 Poole's Calorific Power of Fuels. . . 8vo, 3 oo Reid's Course in Mechanical Drawing 8vo, 2 oo Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, 3 oo Richard's Compressed Air i2mo, i 50 Robinson's Principles of Mechanism 8vo, 3 oo Schwamb and Merrill's Elements of Mechanism 8vo, 3 oo Smith's (O.) Press- working of Metals 8vo, 3 oo Smith (A. W.) and Marx's Machine Design 8vo, 3 oo Thurston's Treatise on Friction and Lost Work in Machinery and Mill Work 8vo, 3 oo Animal as a Machine and Prime Motor, and the Laws of Energetics . i2mo, i oo Tillson's Complete Automobile Instructor i6mo, i 50 Morocco, 2 oo Warren's Elements of Machine Construction and Drawing 8vo, 7 -50 Weisbach's Kinematics and the Power of Transmission. (Herrmann Klein.) 8vo, 5 oo Machinery of Transmission and Governors. (Herrmann Klein.). .8vo, 5 oo Wolff's Windmill as a Prime Mover 8vo, 3 oo Wood's Turbines 8vo, 2 50 MATERIALS OP ENGINEERING. * Bovey's Strength of Materials and Theory of Structures 8vo, 7 50 Burr's Elasticity and Resistance of the Materials of Engineering. 6th Edition. Reset 8vo, 7 50 Church's Mechanics of Engineering 8vo, 6 oo * Greene's Structural Mechanics 8vo, 2 50 Johnson's Materials of Construction 8yo, 6 oo Keep's Cast Iron 8vo, 2 50 Lanza's Applied Mechanics 8vo, 7 50 Martens's Handbook on Testing Materials. (Henning.) 8vo, 7 50 Maurer's Technical Mechanics 8vo, 4 oo Merriman's Mechanics of Materials 8vo, 5 oo * Strength of Materials I2mo, i oo Metcalf 's Steel. A Manual for Steel-users I2mo, 2 oo Sabin's Industrial and Artistic Technology of Paints and Varnish 8vo, 3 oo Smith's Materials of Machines I2mo, i oo Thurston's Materials of Engineering 3 vols., 8vo, 8 oo Part II. Iron and Steel 8vo, 3 50 Part III. A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo, 2 50 Wood's (De V.) Treatise on the Resistance of Materials and an Appendix on the Preservation of Timber 8vo, a oo Elements of Analytical Mechanics 8vo, 3 oo Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and Steel 8vo, 4 oo STEAM-ENGINES AND BOILERS. Berry's Temperature-entropy Diagram i2mo, i 25 Carnot's Reflections on the Motive Power of Heat. (Thurston.) i2mo, I 50 Creighton's Steam-engine and other Heat-motors 8vo, 500 Dawson's "Engineering" and Electric Traction Pocket-book. . . . i6mo, mor., 5 oo Ford's Boiler Making for Boiler Makers i8mo, i oo Goss's Locomotive Sparks 8vo, 2 oo Locomotive Performance 8vo, 5 oo Hemenway's Indicator Practice and Steam-engine Economy 1210.0, 2 oo 14 Button's Mechanical Engineering of Power Plants 8vo, 5 oo Heat and Heat-engines 8vo : 5 oo Kent's Steam boiler Economy 8vo, 4 oo Kneass's Practice and Theory of the Injector 8vo, i 50 MacCord's Slide-valves 8vo, 2 oo Meyer's Modern Locomotive Construction 4to, 10 oo Peabody's Manual of the Steam-engine Indicator I2mo. i 50 Tables of the Properties of Saturated Steam and Other Vapors 8vo, i oo Thermodynamics of the Steam-engine and Other Heat-engines 8vo, 5 oo Valve-gears for Steam-engines 8vo, 2 50 Peabody and Miller's Steam-boilers 8vo, 4 oo Pray's Twenty Years with the Indicator Large 8vo, 2 50 Pupin's Thermodynamics of Reversible Cycles in Gases and Saturated Vapors. (Osterberg.) i2mo, i 25 Reagan's Locomotives: Simple, Compound, and Electric. New Edition. Large 12 mo, 3 50 Rontgen's Principles of Thermodynamics. (Du Bois.) 8vo, 5 oc Sinclair's Locomotive Engine Running and Management I2mo, 2 oo Smart's Handbook of Engineering Laboratory Practice i2mo, 2 50 Snow's Steam-boiler Practice 8vo, 3 oo Spangler's Valve-gears 8vo, 2 50 Notes on Thermodynamics i2mo, i oo Spangler, Greene, and Marshall's Elements of Steam-engineering 8vo, 3 oo Thomas's Steam-turbines 8vo, 3 50 Thurston's Handy Tables 8vo, i 50 Manual of the Steam-engine 2 vols., 8vo, 10 oo Part I. History, Structure, and Theory 8vo, 6 oo Part II. Design, Construction, and Operation 8vo, 6 oo Handbook of Engine and Boiler Trials, and the Use of the Indicator and the Prony Brake 8vo, 5 oo Stationary Steam-engines 8vo, 2 50 Steam-boiler Explosions in Theory and in Practice i2mo, i 50 Manual of Steam-boilers, their Designs, Construction, and Operation . 8vo, 5 oo Wehrenfenning's Analysis and Softening of Boiler Feed-water (Patterson) 8vo, 4 oo Weisbach's Heat, Steam, and Steam-engines. (Du Bois.) 8vo, 5 oo Whitham's Steam-engine Design 8vo, 5 oo Wood's Thermodynamics, Heat Motors, and Refrigerating Machines. . .8vo, 4 oo MECHANICS AND MACHINERY. Barr's Kinematics of Machinery 8vo, 2 50 * Bovey's Strength of Materials and Theory of Structures 8vo, 7 50 Chase's The Art of Pattern-making I2mo, 2 50 Church's Mechanics of Engineering 8vo, 6 oo Notes and Examples in Mechanics 8vo, 2 oo Compton's First Lessons in Metal- working I2mo, i 50 Compton and De Groodt's The Speed Lathe I2mo, i 50 Cromwell's Treatise on Toothed Gearing I2mo, i 50 Treatise on Belts and Pulleys I2mo, i 50 Dana's Text-book of Elementary Mechanics for Colleges and Schools. .i2mo, i 50 Dingey's Machinery Pattern Making i2mo, 2 oo Dredge's Record of the Transportation Exhibits Building of the World's Columbian Exposition of 1893 4to half morocco, 5 oo Du Bois's Elementary Principles of Mechanics : Vol. I. Kinematics 8vo, 3 50 VoL II. Statics 8vo, 4 oo Mechanics of Engineering. Vol. I Small 4to, 7 50 VoL II Small 4to, 10 oo Durley's Kinematics of Machines 8vo, 4 oo 15 Fitzgerald's Boston Machinist i6mo, i oo Flather*s Dynamometers, and the Measurement of Power i2mo, 3 oo Rope Driving i2mo, 2 oo Goss's Locomotive Sparks 8vo, 2 oo Locomotive Performance 8vo, 5 oo * Greene's Structural Mechanics 8vo, 2 50 Hall's Car Lubrication i2mo, i oo Holly's Art of Saw Filing i8mo, 75 James's Kinematics of a Point and the Rational Mechanics of a Particle. Small 8vo, 2 oo * Johnson's (W. W.) Theoretical Mechanics i2mo, 3 oo Johnson's (L. J.) Statics by Graphic and Algebraic Methods 8vo, 2 oo Jones's Machine Design: Part I. Kinematics of Machinery 8vo, i 50 Part II. Form, Strength, and Proportions of Parts 8vo, 3 oo Kerr's Power and Power Transmission 8vo, 2 oo Lanza's Applied Mechanics 8vo, 7 50 Leonard's Machine Shop, Tools, and Methods 8vo, 4 oo * Lorenz's Modern Refrigerating Machinery. (Pope, Haven, and Dean.). 8vo, 4 oo MacCord's Kinematics; or, Practical Mechanism 8vo, 5 oo Velocity Diagrams .' 8vo, i 50 * Martin's Text Book on Mechanics, Vol. I, Statics i2mo, i 25 Maurer's Technical Mechanics 8vo, 4 oo Merriman's Mechanics of Materials 8vo, 5 oo * Elements of Mechanics i2mo, i oo * Michie's Elements of Analytical Mechanics 8vo, 4 oo * Parshalland Hobart's Electric Machine Design 4to, half morocco, 12 50 Reagan's Locomotives : Simple, Compound, and Electric. New Edition. Large i2mo, 3 oo Reid's Course in Mechanical Drawing 8vo, 2 oo Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, 3 oo Richards's Compressed Air i2mo, i 50 Robinson's Principles of Mechanism 8vo, 3 oo Ryan, Norris, and Hoxie's Electrical Machinery. Vol. 1 8vo, 2 50 Sanborn's Mechanics : Problems Large i2mo, i 50 Schwamb and Merrill's Elements of Mechanism 8vo, 3 oo Sinclair's Locomotive-engine Running and Management I2mo, 2 oo Smith's (O.) Press-working of Metals 8vo, 3 oo Smith's (A. W.) Materials of Machines i2mo, i oo Smith (A. W.) and Marx's Machine Design 8vo, 3 oo Spangler, Greene, and Marshall's Elements of Steam-engineering 8vo, 3 oo Thurston's Treatise on Friction and Lost Work in Machinery and Mill Work 8vo, 3 oo Animal as a Machine and Prime Motor, and the Laws of Energetics. i2mo, i oo Tillson's Complete Automobile Instructor i6mo, i 50 Morocco, 2 oo Warren's Elements of Machine Construction and Drawing 8vo, 7 50 Weisbach's Kinematics and Power of Transmission. (Herrmann Klein.). 8vo, 5 oo Machinery of Transmission and Governors. (Herrmann Klein.). 8vo, 5 oo Wood's Elements of Analytical Mechanics 8vo, 3 oo Principles of Elementary Mechanics I2mo, i 25 Turbines 8vo, 2 50 The World's Columbian Exposition of 1893 ... 4to, i oo MEDICAL. De Fursac's Manual of Psychiatry. (Rosanoff and Collins.) Large i2mo, 2 50 Ehrlich's Collected Studies on Immunity. (Bolduan.) 8vo, 6 oo Hammarsten's Text-book on Physiological Chemistry. (Mandel.) 8vo, 4 oo 16 Lassar-Cohn's Practical Urinary Analysis. (Lorenz.) i2mo, i oo * Pauli's Physical Chemistry in the Service of Medicine. (Fischer.) . . . 12100, i 25 * Pozzi-Escot's The Toxins and Venoms and their Antibodies. (Cohn.). i2mo, i oo Rostoski's Serum Diagnosis. (Bolduan.) I2mo, i oo Salkowski's Physiological and Pathological Chemistry. (Orndorff.) 8vo, 2 50 * Satterlee'* Outlines of Human Embryology I2mo, i 25 Steel's Treatise on the Diseases of the Dog 8vo, 3 50 Von Behring's Suppression of Tuberculosis. (Bolduan.) i2mo, i oo Wassermann's Immune Sera : Haemolysis, Cytotoxins, and Precipitins. (Bol- duan.) i2mo, cloth, i oo Woodhull's Notes on Military Hygiene 1 6mo, i 50 * Personal Hygiene i2mo, i oo Wulling's An Elementary Course in Inorganic Pharmaceutical and Medical Chemistry i2mo, 2 oo METALLURGY. Egleston's Metallurgy of Silver, Gold, and Mercury: Vol. I. Silver 8vo, 7 50 VoL II. Gold and Mercury 8vo, 7 50 Goesel's Minerals and Metals: A Reference Book , i6mo, mor. 3 oo * Iles's Lead-smelting i2mo, 2 50 Keep's Cast Iron 8vo, 2 50 Kunhardt's Practice of Ore Dressing in Europe 8vo, i 50 Le Chatelier's High-temperature Measurements. (Boudouard Burgess. )i2mo, 3 oo Metcalf's Steel. A Manual for Steel-users 12210, 2 oo Miller's Cyanide Process i2mo, i oo Minet's Production of Aluminum and its Industrial Use. (Waldo.). .. . I2mo, 2 50 Robine and Lenglen's Cyanide Industry. (Le Clerc.) 8vo, 4 oo Smith's Materials of Machines I2mo, i oo Thurston's Materials of Engineering. In Three Parts 8vo, 8 oo Part II. Iron and SteeL 8vo, 3 50 Part HI. A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo, 2 50 Ulke's Modern Electrolytic Copper Refining 8vo, 3 oo MINERALOGY. Barringer's Description of Minerals of Commercial Value. Oblong, morocco, 2 50 Boyd's Resources of Southwest Virginia 8vo, 3 oo Map of Southwest Virignia Pocket-book form. 2 oo * Browning's Introduction to the Rarer Elements 8vo, I 50 Brush's Manual of Determinative Mineralogy. (Penfield.) 8vo, 4 oo Chester's Catalogue of Minerals^ 8vo, paper, i oo Cloth, i 25 Dictionary of the Names of Minerals 8vo, 3 50 Dana's System of Mineralogy Large 8vo, half leather, 12 50 First Appendix to Dana's New " System of Mineralogy." Large 8vo, i oo Text-book of Mineralogy 8vo, 4 oo Minerals and How to Study Them 1 2 mo, i 50 Catalogue of American Localities of Minerals Large 8vo, i oo Manual of Mineralogy and Petrography I2mo 2 oo Douglas's Untechnical Addresses on Technical Subjects i2mo, i oo Eakle's Mineral Tables 8vo, i 25 Egleston's Catalogue of Minerals and Synonyms 8vo, a 50 Goesel's Minerals and Metals : A Reference Book i6mo.mor. 300 Groth's Introduction to Chemical Crystallography (Marshall) 12 mo, i 25 17 Iddings's Rock Minerals 8vo, 5 oo * Martin's Laboratory Guide to Qualitative Analysis with the Blowpipe, lamo, 60 Merrill's Non-metallic Minerals: Their Occurrence and Uses 8vo, 4 oo Stones for Building and Decoration 8vo, 5 oo * Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests. 8vo, paper, 50 * Richards's Synopsis of Mineral Characters i2mo, morocco, i 25 * Ries's Clays: Their Occurrence, Properties, and Uses 8vo, 5 oo Rosenbusch's Microscopical Physiography of the Rock-making Minerals. (Iddings.) 8vo, 5 oo * Tillman's Text-book of Important Minerals and Rocks 8vo, 2 oo MINING. Boyd's Resources of Southwest Virginia 8vo, 3 oo Map of Southwest Virginia Pocket-book form 2 oo Douglas's Untechnical Addresses on Technical Subjects i2mo ; i oo Eissler's Modern High Explosives 8-3 4 ->o Goesel's Minerals and Metals : A Reference Book i6mo, mor. 3 oo Goodyear's Coal-mines of the Western Coait of the United States i2ino, 2 50 Ihlseng's Manual of Mining 8vo, 5 oo * Iles's Lead-smelting I2mo, 2 50 Kunhardt's Practice of Ore Dressing in Europe 8vo, i 50 Miller's Cyanide Process . i2mo, i oo O'Driscoll's Notes on the Treatment of Gold Ores 8vo, 2 oo Robine and Lenglen's Cyanide Industry. (Le Clerc.) 8vo, 4 oo * Walke's Lectures on Explosives 8vo, 4 oo Weaver's Military Explosives 8vo, 3 oo Wilson's Cyanide Processes i2mo, i 50 Chlorination Process i2mo, i 50 Hydraulic and Placer Mining i2mo, 2 oo Treatise on Practical and Theoretical Mine Ventilation I2mo, i 25 SANITARY SCIENCE. Bashore's Sanitation of a Country House i2mo, i oo * Outlines of Practical Sanitation i2mo, i 25 Folwell's Sewerage. (Designing, Construction, and Maintenance.) 8vo, 3 oo Water-supply Engineering 8vo, 4 oo Fowler's Sewage Works Analyses i2mo, 2 oo Fuertes's Water and Public Health i2mo, i 50 Water-filtration Works izmo, 2 50 Gerhard's Guide to Sanitary House-inspection 9 i6mo, i oo Hazen's Filtration of Public Water-supplies 8vo, 3 oo Leach's The Inspection and Analysis of Food with Special Reference to State Control 8vo, 7 50 Mason's Water-supply. (Considered principally from a Sanitary Standpoint) 8vo, 4 oo Examination of Water. (Chemical and Bacteriological.) I2mo, * Merriman's Elements of Sanitary Engineering .8vo, Ogden's Sewer Design i2mo, Prescott and Winslow's Elements of Water Bacteriology, with Special Refer- ence to Sanitary Water Analysis I2mo, * Price's Handbook on Sanitation i2mo, Richards's Cost of Food. A Stuiy in Dietaries I2mo, Cost of Living as Modified by Sanitary Science i2mo, Cost of Shelter i2mo, 18 Richards and Woodman's Air Water, and Food from a Sanitary Stand- point 8vo, 2 oo * Richards and Williams's The Dietary Computer 8vo, i 50 Rideal's S wage and Bacterial Purification of Sewage 8vo, 4 oo Disinfection and the Preservation of Food 8vo, 400 Turneaure and Russell's Public Water-supplies 8vo, 5 oo Von Behring's Suppression of Tuberculosis. (Bolduan.) i2mo, i oo Whipple's Microscopy of Drinking-water 8vo, 3 So Winton's Microscopy of Vegetable Foods 8vo, 7 50 Woodhull's Notes on Military Hygiene i6mo, i 50 * Personal Hygiene i2mo, i oo MISCELLANEOUS. Emmons's Geological Guide-book of the Rocky Mountain Excursion of the International Congress of Geologists Large Svo, i 50 Ferrel's Popular Treatise on the Winds Svo, 4 oo Gannett's Statistical Abstract of the World 241110 75 Haines's American Railway Management I2mo, 2 50 Ricketts's History of Rensselaer Polytechnic Institute, 1824-1894.. Small Svo, 3 oo Rother ham's Emphasized New Testament c Large Svo, 2 oc The World's Columbian Exposition of 1893 4to, i oc Winslow's Elements of Applied Microscopy i2mo. i sc HEBREW AND CHALDEE TEXT-BOOKS. Green's Elementary Hebrew Grammar I2mo, i 25 Hebrew Chrestomathy Svo, 2 oo Gesenius's Hebrew and Chaldee Lexicon to the Old Testament Scriptures. (Tregelles.) Small 4to, half morocco, 5 oo Letteris's Hebrew Bible Svo, 2 25 19 UNIVERSITY OF CALIFORNIA LIBRARY This is the date on which this book was charged out. 7 - 8 b' REC'D LD [30m-6,'ll] UNIVERSITY OF CALIFORNIA LIBRARY