6> . Z^- ^lylfM^i^ /O^ ^'O'-^^ •J'^-3^^ •COtJW «J"0<--'>»'^ivJ ^l«» ■JKJ<^\, -»'>^^OW <^'^ REPORT Of THOMAS C. KEEFER, Esq., ^iir-''"^ CIVIL ENGINEER. ON PROPOSED I 11 WATER SUPPLY FOR DARTMOUTH, N. S. II! I % $ $ 1949 Ll t-s- HALIFAX, N. ^ ♦n PRINTED BY JAMES BOWES & SONS/ 4 ' 1876. ■^ OTTAWA, Ttii March, 1876. O. J. TROOP, Esq., Warden, Dartmouth, N. S. Dear Sir, — I have received from Mr. Murpliy, C. E., the results of the surveys which I recoiutneuded to you iu my letter of 18th August last. It may be proper to repeat that having examined the vicinity of Dartmouth last summer, I v^^as fully convinced that the only adequate sources of supply within financial reach of your town were the three lakes on the Preston road, known as " Lamont," ''Topsail," and " Loon" Lakes, which are over 220 feet above tide, — within 3 feet of same level, and divided from each other by low ground, through which a connection of dieir waters may be easily made. Apparently there was abundance of water in this quarter, there being a Mill on the outlet of Lamont Lake ; — and it may be ac- cepted as a rule that any source of water supply for a town is at lea.st a doubtful one if it is not a " mill stream." The fact that a Mill was in operation there was to me the strongest reason for believing iu the sufficiency of the supply ; but I was unable to pronounce upon this important point until the acreage drained into these Lakes was ascertained. The extent of water surface is not always a guide to the value of these Lakes. If on a summit level they may have a mere rim of drainage area around them, furnishing annually little more than will supply the avaporation, and when once drawn down, it would require a series of years to fill them up again. Subterranean sources of supply are sometimes ascribed to such Lakes, but the simple experiment of drawing one of them down will explode this theory. This rather expensive test was made by the City of London, Ontario, two or three years ago. It requires but little reflection to be convinced that all our sources of fresh water supply are derived from the clouds, and that the annual quantity of water which any stream wih afford depends upon the annual amount of rain and snow fall, which is precipitated upon the drainage area due to that stream. A portion of this water is evaporated, that from the land being the smaller portion (varying very much with the character of the soil on [2] >yhich it falls:) that from the water surface being the greater por- tion if not the whole. Evaporation jroen on at all temperatures, and for our latitudes is a tolorahly constant quantity; but rain-fall varies nearly one hundred per cent between the great Lakes in Ontario and the neighbourhood of Halifax. While here evaporation disposes of one-half of the rain-lall, with you it would seldom exceed one- third, and your remainder would be about double that of ours; that is the available annual yield of water from an acre in the neighbourhood of Dartmouth will be about double that from an acre near Hamilton, Out. Evaporation is greatest from rock and clay surfaces, especially if cleared, and least from gravel, sand and forest land, which immediately absorb and protect the rain- fall from the sun and heated air. In this respect you are fortunate about Dartmouth, and will suffer less loss than usual from this action of the sim, who will always be your greatest competitor for a share in the water-shed of your Lakes, The second point in importance to be <letermined by the surveys recommended, was the depth of the Lakes which it was proposed to make your Reservoir's. For purposes of town supply, storage is as important as drainage urea. Many streams furnish abundant annual supplies, which are useless for town purposes, unless the surplus in freshets can be stored up for a season of drought. Your Lakes are magnificient natural reservoir's, but assuming a pro- longed drounjht, during which they would receive no supply at all from the clouds, while all tha while they would be losing the highest amount from evaporation : it becomes necessary to know to what extent they may be drawn upon. A common practice is to raise the level by damming the outlet, and where the Lakes are shallow this is necessary. The supply pipe should have its mouth from 5 to 10 feet below the Lake surface, in order to draw off that qiuintity if necessary ; and the raising of the natural surface faci- litates and cheapens the work of leading out his pipo On the other hand, unless the banks are bold, raising the level is objectionable, as it increases the surface exposed to evaporation, and floods more land, producing more shallow water and subaque- ous vegetation, which, when exposed in a time of drought, decays and taints the whole body of the water. As Lament and Topsail Lakes have much low border, it was evident from inspection that it would be desirable to avoid raising their surfaces. If this had been necessary there would have been'^ in addition to the value of the land so drowned, a much greater expenditure to be provided for in order to remove all vegetable matter from the flooded border, :.. The results of the surveys are most satisfactory. The water- ' shed of L;imont and Topsail Lakes, exclusive of their water sur- faces, is 540 acres, and that of Loon Lake 630 acres, or a total of 1170 acres. .[3] The area of water surfaces of the Lakes is as follows : — Lamoiit, acres, 24. 2.2!). Topsail, " 144. 2.12. Loou, " 193. 0.18. 362. 0.19. Add laud draiued, 1 170. 0.0. Total, 1532 acres. The averapre raio-fall at Dartmouth is i)r()l»al)ly not loss than 50 inches, but as there is one year (ISiiO) in which 39 inches only has been recorded, I think the rain-fall of that year may safely be taken as the minimum, and it is with that we have to do at present. AUowiufr 24 inches of available water, from 1100 acres land, drained by those three Lakes, this would give GO gallons per diem each, to a" population of 27,000. As the storage is so large, a higher per centage of the rain-fall than that due to the minimum year can be utilized, because the Lakes, if drawn down only five feet, would supply over one million gallons daily for a whole year without any incoming water. When it becomes necessary to use Loou Lake the surplus storage will be ample to make up the deficiency of an exceptionally dry year. It is therefore evideut that the first great desideratum, ample quantity of water, not only for the present but for the future, cao be obtained from this quarter. 1 be'.ieve that with the addition of Loon Lake a population as large as Halifax can be supplied in the future. For the wants of Dart- mouth for many years to come, Lamont aud I'opsail Lakes will afford an ample supply ; and the soundings taken shew that it will not be tiecessary to raise their level. This will avoid much expense and secure the best quality of water. The depth of the Topsail and Lamont Lakes, ranges between 15 and 20 feet, and this makes them natural Reservoir's, to be drawn upon in dry weather. Loon Lake, however, being 3 feet lower than Topsail, must be raised before it can be used ; Ijut that necessity will not arise with the present generation. Topsail Lake alonv, will provide an ample supply for many years, and its value is greatly enhanced by the fact that the supply from it can be more than doubled in the future, by the addition of Loon Lake to the system. When the population of Dartmouth becomes so large that more water will be wanted than Topsail Lake can supply, if the full sized pipe is now adopted, nothing further is required than to dam the Loon Lake outlet, and cui. a ditch between it aud Topsail L{ ke. In order fully to draw down the surface of Topsail Lake it will be necessary to deepen the channel which connects it with [4] Lnmont Lake. This may be postponed until the necessity arises, as il can bo done to bottor advanta^je when tbe water is low, and it may be some years before it will bo necessary. Tbe mouth of the supply pipe for the town should be placed about ten feet (or not less than eight feet) below the level of Top- sail Lake. This will not only enable you to draw the lar^^iest amount from Topsail Lake, but when Loon Lake is brought in. its great contents may then be drawn upon to the extent of at least five feet from its raised surface The headvvorks, gate house, screens, &c., can be put in below the present dam, near the Mill, on dry ground, and a new dam built below them, after which the old one may be cut through and the Topsail Lake level brought down to the Mill. The pipe track shouhl follow the highway where it is direct and in favorable excavation ; but if to shorten the length or to avoid rock or deep excavations, it will be better to go through privnte property. The route should be selected with c^rre, on as good grades as the ground will afford, avoiding all intermediate summits as far as possible, especially any which ri.se above the line of a continuous uniform gradient from the mouth of the pipe to Dart- mouth. Where rock excavation occurs it will be better and cheaper to arrange the pipe levels as far as possible to keep above the rock, and to embank over the pipe and enter on private pro- perty for this purpose ; if the highway is rock, or to get around a high point, wherever this course may be followed. The size of your pipe should be as large as can be afforded at present. It is usual to provide a pipe capable of passing a supply for say double the pre.sent population. Sixty gallons per head, per diem, is considered a liberal supply ; and although there are some places using more, the greater number are under this. Dartmouth, however, being upon the salt water, and an eligible situation for manufacturing establishments, should (with an un- limited gravitation supply under high pressure) anticipate the highest rate of consumption per head. In large places the esti- mate for domestic use, as above, is always in excess of that re- quired for another mo.st important purpose, the extinguishment of fires, but in smaller towns this is reversed. For efficiency in this direction, a certain provision is necessary without reference to population ; and. in the case of Dartmouth, I think this is the consideration whieh ought to determine the size of pipe to be u.sed. For the domestic wants of Dartmouth (with a population of 6000) a six inch pipe would afford an ample supply from Topsail Lake ; but for fire and manufaeturing purpo.ses the size should be twelve inches. With such a pipe you can dispense with fire engines of all kinds, in all parts of the town, not more than 12o feet above tide. Moreover, with ample capacity of pipe, the water may be freely used for small occa.>iional powers, where steam could not be afford- C(l, such aa warehouse hoists, priuting presses, sewing machinos, church orjjans, &c., &c. Lastly, with such a pipe it wouhl not be necessary to buy a second one when the jrrowth of Dartmouth wouhl call for tlu addition of Loon Lake to your system. COST OF THE WORKS. The cost of brinjrin;; in the water will depend upon the size of pipe adopted, and I have prepared a table she win;,' the relative cost and efficiency of different sizes between 6 and 12 inch. From this it will be seen that a twelve inch pipe will be more efficient than five six inch pipes, while it will only cost twice as much. For fire purposes the smallest size which could be entertained would be 1) inches, and this wonhl not he efficicMit on the hi^rher level*. The fact that Dartnu)uth extends so hi;,'h above tide, and that these elevations are the most helpless in case of fire, renders it doubly important that the delivery should be as efficient as possible on the hiorh levels ; moreover these hi<j:h levels comprise a lar;?e por- tion of the taxable area, and if efficicuitly supplied their taxable value will be doubled, and the rate will be cheerfully borne because, with efficient water supply for house and garden purposes and for fire protection, they will become the most eligible building sites. The difference in cost between a 9 inch and a 12 inch pipe will not exceed S 1 0,000 ; and the Dartmouth Water Works, with a twelve inch pipe, will be worth at least double what they will be with a nine inch one. The difference, in your favor, in the annual cost of Fire Insurance, with the larger pipe, will in a few years pay for the extra cost. The cost of the distribution will depend upon the extent to which it is carried, and the amount of rock excavation which may be encountered. Exclusive of land and water rights, the necessary present ex- penditure to bring in a 12 inch pipe, with the headworks and pipe track expenditure, will range between $40 000 and $50,000, antl the co.st of distributing the same will be S6000 per mile, in earth ex- cavation, and nearly double this amount wherever there is an average of 4 feet of rock. This includes hydrants, valves and special castings and all the work of laying and setting complete. T(ie want of correct maps, shewing the position of the roads and Lakes, makes it impossible to form any opinion as to how direct a route the Preston Road gives between Dartmouth and Topsail Lake. If the route can be shortened, or the pipe kept on a higher level until it approaches Dartmouth, a route through private property may be preferable. It is not necessary to pjTr- chase a right of way, or create a " severance," — a " servitude" [6] only i8 require.!. The -round over the pipe can, except in cuttin-s and embftukments, be cultivated aa usual. ° In conclu.siou I must say that I know of no town more favor- ably situated for an abundant, efficient and economical supply of the best quality of water thun Dartmouth. I would also say that I know of no town which has regretted water works expen.liture • or which has not regretted that that expenditure was, in the first pla.e, too small. Everywhere the complaint is,--waut of sufficieut foresight and confidence in the fulure,-want of pluck to carry out, on a liberal .scale, works upon which so much of the future success of the municipality depends. With such facilities as you possess 1 ain satisfied n.. better investment can be ,nade ; nothin- which, for the same outlay and in the same time, will add ,so much and so rapidly to the population and wealth of Dartmouth, as the bringing of an abundant supply of pure water from so high an elevation as Topsail Lake. I have the honor to be, . "Sir, Your obedient servant, ♦ . THOS. C. KEEPER. .Arr . !.„, ;- t'- -. ■-. ' ■ ' '\H ' ',■ I. .'•' ' ,?•'• li , . ' <■-■•■ , 4> '»• a. " "S "S w * :. 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