10 19' REPORT ON THE DAM AND WATER POWER DEVELOPMENT AT AUSTIN, TEXAS BY DANIEL W. MEAD NOVEMBER, 1917 DANIEL W. MEAD CHARLES V. SEASTONE CONSULTING ENGINEERS * MADISON, WISCONSIN REPORT ON THE DAM AND WATER POWER DEVELOPMENT AT BY DANIEL W. MEAD NOVEMBER, 1917 DANIEL W. MEAD CHARLES V. SEASTONE CONSULTING ENGINEERS MADISON, WISCONSIN -v /$> A, c.fbo*/im*ftfne f J 1 I 1 _'_!_ 2 G/tJi Rax format fen W 1 1 1 Travis Fkak formation ^yvi:;' tySr - Eagle, forctihatxj FIGURE 3 Section Along West Side of Colorado River at Austin, Texas, Showing Local Fault of Balcones Fault Zone (Austin Folio, U. S. Geol. Survey) THE OLD DAM The solid structure of the original dam, finished in 1893, apparently furnished by its width of base a sufficient resistance to underflow so that it stood for some years. Various leaks developed, however, near the east end of the structure, especially un- der the head gates, and were repaired in an imperfect way. One of these caused con- siderable damage before the completion of the power house. (See Appendix, page 46, Fig. 17.) In 1900 the east half of the original dam over the badly faulted area failed, due to the erosion of the rock below its toe, the undermining of the toe, and possibly to the development of leaks under its foundation. THE NEW STRUCTURE The structure built under the Johnson contract consisted of a reinforced con- crete section built in the opening where the previous dam had been destroyed. (See Fig. 4.) Most of the old structure remaining was utilized practically as it stood and without material betterments. Work on the power house and reservoir was apparently immediately pushed to completion, and operations in the river work were postponed until the years 1913- 14, thus losing the advantage of the lowest average river stages experienced on the Colorado in twenty years of record and bringing the construction period into two of the heaviest years of flow on record. (See Fig. 1, page 10.) Changes in Plans. 15 PLANS AND SPECIFICATIONS The specifications (see Appendix, pages 61 to 65) and plans (see Appendix, page 65) for the work, submitted with the franchise and made a part thereof, were of the most general character. Conditions were further complicated by the right received under the specifications whereby the engineers of the City Water Company were em- powered to make any changes they desired, provided the stability, capacity, com- pleteness or grade of construction were not reduced. (See page 9.) Even these limiting conditions were restricted by the requirement that any difference of opin- ion between the Engineers of the City and of the Company must be arbitrated, a process so cumbersome that it seems to have been waived in every case. The En- gineers of the City could only inspect and suggest, and were practically powerless to initiate betterments or to resist more than radical defects or changes. Detailed K 47O' >K S6O'- - - > 0' 50' 100' UPSTREAM ^-Concrete CvMT Wall u * t / J " " ' " " ' -*= *&'* Oriqina/ 200' 0>d Masonry CtsrofT Yto// -i ;_if ; T-.T . .T ; xt fc. 'fJ^c. 0/cf Masonry CtsfofF Wall Origr/naf Masonry Derm >K Hew Spit/way Section- Floor, El. /75J> niranc&.j< sCrest-^pf New Spillway 'Crest of Prigrincrl 'Spit/way * ^ ' Bottom' of Concrete CuMFWd/f Line of SiH- below Dam fitter Line as shown ty > Orfgriner/Ar/ngs ' FIGURE 4 Plan and Elevation of the Reconstruction of the Austin Dam under the Con- tract with William D. Johnson, (from Eng. News June 3, 1915.) plans and specifications were to be furnished before work was begun. The City, however, never received a complete set of plans but in lieu of this the Resident En- gineer furnished copies of the principal detailed drawings, with a list of other draw- ings made, and an offer to furnish such as the City might desire. The City on its part made no demands for complete details and has only an incomplete plan of the work on file. CHANGES IN PLANS The original reinforced concrete structure (see A. Fig. 5, page 17) had diagonal cross walls, spaced 24-foot centers, and on the basis of the scale of the drawing was deficient in strength. On Nov. 28, 1911, this plan, with the approval of the City's Engineer and the City Council, was changed to a type having cross walls normal to the axis of the dam (see B. Fig. 5, page 17), and spaced 20- foot centers, and with the interval of the crest piers increased. Both of these changes were improvements but the plan still remained indefinite in detail and defective in strength. In May, 1912, more detailed plans were submitted on which much more definite information was given. These plans were 'submitted to the City's Engineer who 16 Report on the Dam at Austin, Texas. after an examination approved them but failed to call the attention of the City offi- cials to a radical change in width, which change he evidently did not interpret as a change in stability, capacity, completeness or grade of construction. The original design and the plans substituted in November, 1911 called for a dam with a width parallel to the stream of 125'9". The detailed plans of May, 1912 (see C, Fig. 5, page 17), provided for a base width of 93 feet. The new plans also called for additional thickness in the decks of the structure and gave the reinforcement in detail, and altogether was a better and stronger structure than in- dicated by either of the previous plans. The force diagrams (see B, Fig. 6, page 18) show that the new plan repre- sents a lighter structure, and in consequence the resultant pressure makes a less angle with the base line, and theoretically the dam is more liable to slip on its founda- tions or on any underlying clay seams ; but the improvements in other ways are so marked that I believe the change in width is of practically no moment. Various other changes in details were made some of which were material betterments and others, including the change in width of dam, were undoubtedly made to cheapen construc- tion; others were forced by physical conditions. The attention of the City Officials has already been called to many of the changes made, by the report of Mr. S. S. Posey (see C, Fig. 6, page 18). THE EFFECTS OF CHANGES IN PLANS AND SPECIFICATIONS Betterments. A number of the changes made were distinct betterments to the plans as originally proposed. Such changes are as follows: 1. Change in Type. The change in type of dam from diagonal to normal cross walls was a distinct advantage in that it led to simplicity of design. 2. Change in Spacing of Walls. The reduction in the spacing of cross walls from 24 to 20 feet was a distinct betterment, giving a greater number of points of support to the decks and a better distribution of pressure on the foundations. 3. Increase in Span of Crest Gates. The original plan provides crest gates ten feet wide for the new section and eight feet wide for the old section. These were increased to eighteen feet in width for both sections. This was an improve- ment, and with stronger gates on a stream carrying little drift this plan might have given satisfactory results. 4. Foot Bridge on Dam. The original plans provided for a wooden struc- ture on I-beam supports across the crest of the dam. This was changed to a reinforced concrete structure in order to carry a derrick car for the removal of drift and for the manipulation of the gates. This change was an improvement. 5. Location of Sluice Gates. The change in the location of the sluice gates which brought these gates into the stream channel was an improvement. Changes in Plans. a. /es. o -PI an and Section of Com as Ortgina/ '/y Proposed -Sepf. 22 'CSf- /$//. - Section of Dam as Changed and fljo/y/wed March / 5 (2/3/2. C. P/an and Section of Oam as Cfiangea" and flpprovea/ rfay /OH! /9I2 anaf as Construe/fa"- FIGUBE 5 Original Plan for Reinforced Concrete Dam at Austin, Texas, and Successive Changes made in Same. * a* .i e> ii*.***> * * **' >' * , ^ r 'J ** Report on the Dam at Austin, Texas. FIGURE 6 Force Diagrams of Original and Final Sections of the Austin Dam. Changes in Plans. 19 6. Width of Cross Walls. The base width of the cross walls was shown as one foot in the original plans. This width was increased to 2'6" in construction, which was a change for the better. 7. Thickness of Upstream Deck. The thickness of the upstream deck was increased from 2' to 2'6" at the base, and from V to 1'8" at the top. This change was a betterment essential to the safety of the structure. 8. Power House Floor. The original plans provided for a reinforced con- crete floor supported on I-beams. The floor as built was supported partially on earth fill and partially on reinforced concrete beams. Assuming this work was properly done, this change was an improvement on the plans. 9. Changes in Head Gate Racks. The racks as originally designed and in- stalled permitted drift to enter the penstocks, which caused the frequent break- age of the turbine gates. The change in form of rack later installed, and now in place, was a decided betterment which accomplished its object, although it in- terposed too great a resistance to the free entrance of water. IMMATERIAL CHANGES 1. Change in Width of Plans. The change in the width of the dam from 125'9" to 93' I regard as immaterial. If the dam were otherwise safe, either width of dam would be safe and satisfactory. The narrower design is more eco- nomical and therefore an improvement from an engineering standpoint, but from the point of view of the City, the change is immaterial. 2. Change in Bascule Castings. The bascule castings for the gates were changed from a rack type to a plain type. Either type would have been satis- factory if sufficiently strong for the purpose, and if the gates were otherwise satisfactory. 3. Cutoff Walls below Old Dam. A cutoff wall was planned below the toe of the old dam but was omitted in construction. If this wall was intended to cut off flow under the old dam, its presence would have been a detriment rather than a benefit. Seepage should be stopped at the heel of the dam, and if it reaches the toe should be removed instead of being prevented, in order to reduce uplift pressure on the base of the dam. If this wall had been installed, weep holes in the toe would have become essential. The omission of the wall at the toe is regarded as immaterial. 4. Change in Concrete Mixture. A change was made in the mixture of the concrete used from that required by the specifications by using pit run sand and gravel instead of a definite mixture of cement, sand and stone or screened gravel in the ratio of 1 :2 :4. Mr. Posey states (see Appendix, note 18, page 75) that the pit run gravel was tested frequently for voids, and the voids controlled by the 20 Report on the Dam at Austin, Texas. addition of sand, gravel or stone, and that an excess of cement was used. The probabilities are that the concrete produced was equal to that which would have resulted from the specified mixture. This is confirmed by the appearance of the finished work. DETBIMENTAL CHANGES 1. Detrimental Changes in the Provisions for a Safe Foundation A. Grouting. The specifications for grouting were very indefinite. Grout com- posed of cement mixed with three parts, or less, of sand was to be forced into two- inch holes of unspecified depth which were to be spaced not more than 30 feet apart, or any other method could be used to render the substrata impervious. (See Appen- dix, page 63.) Holes were bored in many cases very close together, perhaps in cases 3 feet or less apart but near the line of the cut-off wall, and they were all 12 feet or less in depth. On the lines of the cross walls, the holes in general were bored only about 4 or 5 feet in depth. The general purpose of this specification was to produce an impervious bottom "to prevent waste" but the safety of the structure was more particularly involved. The inadequacy of the work done is indicated by the leaks now in evidence under the reinforced concrete structure. It is believed that the grouting behind the old dam is also ineffective in preventing seepage and uplift pressure. This work, which was indefinitely specified except as to its object, has been done in an ineffective and in- complete manner, and the conditions resulting threaten the safety of the structure. B. Cut-off Wall Above West Section of the Old Dam. The original plans pro- vide for a cut-off wall adjoining the heel or upstream face of the old dam. Appar- ently, from the scale of the original drawing this wall was to be about 22 feet or more in depth. A shallow cut-off wall was built as part of the so-called "core wall" behind the east section of the old dam. No cut-off wall was built behind the west section of the old dam but inadequate grouting was substituted in shallow holes of a maxi- mum depth of 12 feet, to the detriment of the work. C. Cut-off Walls on Reinforced Concrete Dam. These walls were to be carried down to ' ' solid impervious rock which borings indicated to be at least six feet in thickness." The original drawings indicated that these walls were to be carried to a depth of 22 feet or more below the rockbed of the river. Under parts of the dam it is probable that no six-foot strata of solid rock were available, and the specifica- tions were perhaps impossible so far as that requirement was concerned. These con- ditions made the deep cut-off proposed imperative for safety, but the only substitute furnished was to carry the wall approximately two feet into solid rock, and to at- tempt to solidify cracks and fissures by grouting. In places, however, according to the evidence of the Inspecting Engineer, not even a wall two-feet in depth was con- structed. Changes in Plans. 21 2. Detrimental Changes in the Structure of the Dam and Appurtenances A. Core Wall. The core wall as shown on the plans and as described in the spe- cifications is somewhat indefinite. The original plans submitted with the contract show the bottom of the east end of the core wall at about elevation 120. The revised detailed plans of May, 1912, show the end of this wall lowered to elevation 100. This change is an apparent improvement. The original plans also show the top of the core wall in front of the gate masonry to be at about elevation 172. Evidently it was intended to face the head gate masonry with the concrete of this core wall in order to make the masonry water tight. A slight modification was made in the end of the core wall as planned when it was constructed, several hundred yards of con- crete being omitted by the consent of the City's Engineer and approved by the City Council. As the material at this point was found to be impervious, this change is ap- parently of little moment. The concrete in front of the head gate masonry was om- itted, which was evidently a detriment to the work as this masonry is said to leak when the reservoir is full. B. Pointing the Old Dam. While the old masonry has been pointed in part, this work has not been done in a thorough and workmanlike manner. C. Changes in Gates and Setting. The original plans for the gates showed a fairly well braced gate, but when the gates were widened and redesigned they were built in two sections joined only by thin plates which were to be supported on small bascule piers. While neither design is considered adequate, the change is consid- ered detrimental. The introduction of small center bascule piers to support the gates and reduce the cost of their construction was a detriment inasmuch as these piers ser- iously obstructed the flow. D. Sluice Gates and Sluice Gate Trash Racks. The design for the original sluice gates provided for the sluice gate to be set in a recess in the dam, built in such manner that the hydraulic cylinders would be within the dam and accessible at all times (see A, Fig. 7, page 22). This plan also provided for T-rail trash racks in front of the gates to prevent floating matter entering the gateways and interfering with the proper operation of the gates. In the construction of the plant this plan was changed. The gates together with the hydraulic cylinders were set on the face of the dam (see B, Fig. 7) and no trash racks were provided. This change was a decided detriment. 3. Power Plant Accessories A. The Tail Race. Specifications for the tail race evidently anticipated its ex- cavation through earth and the construction of a tunnel or channel of reinforced concrete ample for the use of the three turbines installed and for an additional tur- bine which might be added at a later date. It was found, however, that the surface of the rock was not far below elevation 100 (low water level) and that much of the excavation would have to be made in rock ; the sum of about $8,335 was apparently expended on this excavation. The presence of this rock rendered concrete unneces- 22 Report on the Dam at Austin, Texas. sary except that a wall might be desirable on the north side of the raceway in order to keep back the debris from the large mass of rock, dirt, etc., located between the tailrace and the foot of the dam. (See Figs. 8 and 9, page 25.) While a de- flecting wall immediately adjoining the power house and north of this raceway is considered advisable in order to protect the exposed draft tubes, it is not believed FIGURE 7 Sections of Sluice Gates as Originally Designed and as Constructed. that such a wall extended for the entire length of the raceway in the main channel would be either effective or desirable. To be effective it would have to be built high and strong in order to prevent detritus being raised over it in times of extreme flood. If built high enough for this purpose, it might prove objectionable on account of creating cross currents near the toe of the dam and by creating a comparatively quiet pool in the tailrace which would cause heavy silt deposits therein. The re- quirements for such a wall can best be obviated by the entire removal of this pile of debris. While the failure to construct a concrete channel is not considered detri- mental, the failure to construct a proper channel which would not be filled with de- bris after every flood is considered a serious detriment to the work. Changes in Plans. 23 B. Penstocks. The penstocks, or intakes as they are termed in the specifications, were to be constructed of first class material throughout and the specifications evi- dently did not anticipate the use of material from the old penstocks installed in 1893, and which had remained in the old plant until the removal in 1911. This material was, according to Mr. S. S. Posey, badly corroded but was used for all of the pen- stock work in the reconstructed plant except for the elbows which were of new ma- terial. The penstocks outside of the building were covered with reinforced concrete ; inside the building they were protected on the inside with " smooth-on" but left un- covered. I have not seen these penstocks in operation and cannot speak concerning their tightness and effectiveness. It is quite possible that some additional protec- tion will be needed inside of the power house. While these penstocks as installed may prove fairly satisfactory, the writer considers the change from the new mater- ial to the old, even with concrete reinforcement, as detrimental to the interests of the work. C. Fourth Penstock. The specifications provide for four penstocks only three of which will be used in the present plant, the fourth being reserved for an additional unit which might be needed later. By the advice of the City's Engineer and with the consent of the City Council this penstock was omitted and other work substi- tuted. If the plant is to be utilized finally for 3300 average continuous horse power, it is believed that the omission of the 4th penstock was evidently a mistake, detri- mental to the installation. While I am not fully informed as to the load factor of the Austin electric plant, it is known from experience that the load factors for such plants are commonly below 35 per cent., and that it is hardly probable even when Austin is able to utilize the full 3300 average horse power that this load factor will increase as high as 40 per cent. On the basis of 35 per cent, load factor, the maxi- mum peak which the plant must carry to utilize the average of 3300 HP would be almost 9500 HP, and if the load factor reaches 40 per cent, it will still require a maxi- mum peak of about 8300 HP. In either case the installation of an additional tur- bine, generator and penstock will finally be necessary to equip the plant to the capa- city for which it is designed. D. Draft Tubes. Both the original plans and the amended plan of Jan., 1912, showed the draft tubes within the power house and discharging through the founda- tion walls. On the details of the machinery setting, dated November, 1912, the draft tubes are first shown projecting in the exposed position in which they were constructed. This change is detrimental to the safety and continuous operation of the plant. DEFECTS IN PRESENT CONDITIONS AND STRUCTURES 1. Foundation Conditions. Having pointed out the various changes in the plans and specifications and their effect on the installation, it is necessary, in compliance with instructions, to point out the defects in the present installation, only part of 24 Report on the Dam at Austin, Texas. which are due to these changes the remainder being due to their inadequacy and in- completeness. The serious foundation conditions at the Austin dam have been discussed at some length in Appendices 1 and 4, and the defects in the present structures have been described in considerable detail in Appendix 5. These defects may be de- scribed briefly as follows : A. Foundation. The foundation of the dam, especially of the new part, is in very bad condition. An attempt was made under the Johnson contract to render this bottom impervious by grouting which however was inadequate in extent and ineffective in results. This is perhaps the most serious defect in the work done and has resulted in two known leaks, and unless remedied will probably result in the early destruction of the new section of the dam. B. Riverbed Below the Dam. The rock below the toe of the new section has been deeply eroded and is in general considerably below the foundations of the cross walls of the dam. (See Fig. 12, page 28.) The irregular foundations of these cross walls are built to different depths and founded on the rough and irregular sur- faces of different strata of rock, which will prevent the slipping of the dam on its foundations. However, there is a danger of the entire structure slipping on the clay seams which are known to underlie at least a part of the structures. A dam with its foundation above the bedrock immediately in front of its toe cannot be regarded as a safe structure, and the present condition will undoubtedly be made worse by every high flood. C. Leakage. The large leak in panel No. 6 of the new dam was discharging ap- proximately 30 cubic feet per second during the writer's examination in August, 1917, when the head on the dam was only 15 feet. This leak is a serious menace to the structure. The leak in panel No. 4, while apparently small, and such other see- page as may occur under the old or new structure may increase and give rise ulti- mately to dangerous conditions. The observations of the U. S. Geological Survey (see Appendix, page 120) show that with the reservoir full to elevation 151 there is leakage into the strata and around the dam of at least 90 cubic feet per second. This leakage if conserved would under a sixty-foot head generate about 600 continuous horse power, and, with the power utilized to even half of the rated capacity of the plant, would be of great value during low water seasons or for about 55 per cent, of the time (on the basis of the flow for the last 20 years). On the basis of $65 per year per horse power, which is essen- tially equivalent to one cent per kilowatt hour, the annual value of this loss by leak- age would be about $17,850, which amount capitalized at ten per cent, would equal $178,500 which is an approximate measure of the amount which may ultimately be expended to advantage in stopping such losses. Changes in Plans. 25 FIGUKE 8 Showing Debris North of the Tailrace and the Filling of the Tailrace by the Flood of Sep- tember, 1915, also Showing the Exposed Position of the Draft Tubes. FIGURE 9 Showing Debris North of the Tailrace and the Filling of the Tailrace by the Flood of Sep- tember, 1915, also Showing the Exposed Position of the Draft Tubes. 26 ; Report on the Darn at Austin, Texas. FIGURE 10 Showing Drift Accumulated above the Dam at Austin during the Flood of September, 1915. FIGURK 11 Showing Drift Accumulated above the Dam at Austin during the Flood of September, 1915. Changes in Plans. 27 2. The Structure of the Dam A. Old Dam Section. The specifications provide that: "portions of the original dam as constructed in 1890-1893 will be retained and used as portions of the finished structure. * * The contractor assumes the responsibility for the perfect stability and effectiveness of the old dam as part of the finished structure." In Appendix 5, pages 124 to 129, 1 have analyzed the section of the old dam under the various conditions of its past and proposed use and have found that it cannot be considered as safe under the conditions which do or probably will obtain. The in- terior masonry is of a poor quality of limestone of local origin, poorly laid in cement mortar. The dam is faced with a good quality of granite which however is not well bonded into the interior masonry. Water finds ready access through the voids to almost every part of the structure. The facing on the east end of the west portion of the dam is apparently loosened from the underlying masonry and shows signs of considerable seepage when the reservoir reaches elevation 151 or higher. I believe there is a real danger of the destruction of the old section if it is al- lowed to remain in its present condition. B. Crest Gates. The gates which were installed on the reconstructed dam were about 18 feet in width, placed between piers two feet in thickness and spaced 20 foot centers. The gates were entirely inadequate to meet the contingencies of flood flow and the piers are so close together as to prevent the passage of the large masses of drift which come down with the floods of the Colorado. (See Figs. 10 and 11, page 26.) The expense involved in the construction of the gate piers and gates was not large, probably amounting to about $40,000, and would have been warranted if the gates could have been cheaply maintained and successfully operated. I believe how- ever that practically no gates which can be installed can successfully pass the heavy drift of the Colorado at times of great floods without great difficulty and large ex- pense. The construction of any gates which may be expected to take care of these conditions in a reasonably economical manner will cost about $363,000. (See Appen- dix 7, page 173.) An analysis of the comparative power which would be available at 60 and 65 foot heads shows that the extra power available with the 65-foot head is not sufficient to pay the interest, depreciation and maintenance on such gates and that the dam can be more economically maintained at the 60-foot head. (See Appen- dix 6, pages 144 et seq.) C. Sluice Gates. The sluice gates are improperly set and poorly designed ; two of them are now out of use. The sluiceways were partially destroyed on account of defective design. No racks were provided to prevent the clogging of these gates. D. Passageway in the Dam. The passageway in the dam is provided with a wooden walk which is in a weakened condition from decay and soon will be unsafe. Its railing has not been painted and is badly corroded. 28 Report on the Dam at Austin, Texas. Cfsr ft.. tow MCtree ft.. < I -1 " i _-Ji V-A_ __^^. r. J i 1 h - 4 ^ 1^ " i^ ' PXOf/L OF Af/0 Afe.A FIGURE 12 Sections of the Austin Dam Showing Erosion below the Toe and Depth of Erosion below Foundations of New Dam. (Fractured and laminated conditions of the f oxidation rock probably exaggerated to illustrate possible danger of sliding.) Changes in Plans. 29 3. Plant Accessories A. Head Gate Masonry. The head gate masonry is said to leak considerably when the reservoir is full. B. Head Gate Trash Racks. The head gate trash racks are improperly built to admit water freely to the penstock. C. Head Gate Hoists. The head gate hoists are of a cheap and inadequate de- sign, such as are ordinarily used only on country mill dams. D. Tail Race. The tail race is partially filled and is probably of insufficient depth. With the great pile of debris between it and the dam every considerable flood will obstruct the raceway by washing in material from that source. E. Draft Tubes. The draft tubes are exposed to the drift which accompanies every flood. The north one has already been injured by floating drift. They have been rendered temporarily tight by the use of Portland cement mortar but are ap- parently not in satisfactory condition. F. Pumps. Of the three pumps of four-million gallons capacity each, furnished in lieu of two pumps of 6-million gallons capacity each in accordance with the con- tract, the one installed at the north station has been broken through the discharge nozzle by the strain set up on account of the imperfect alignment of the discharge piping. Of the two installed in the main pumping station, one is badly worn with sand to an extent which must make its operation exceedingly inefficient. The bear- ings on all of these pumps are said to heat badly during operation. Gr. Station Equipment, etc. The general condition of the penstocks, station equipment, and many other details cannot be well ascertained until the plant is put into operation. Undoubtedly some defects may be expected to develop in addition to those enumerated above. REMEDIES 1. Foundation Conditions A. Foundation at the Heel of the Dam. The foundation rock at the heel of the dam should be rendered practically impervious by grouting through holes spaced not more than six feet apart, and in two rows spaced about six-foot centers, the holes of one row alternating with those of the second row. The holes should be at least 50 feet in depth and the grout should be of slow setting Portland cement used neat. The work must be done with every care and precaution. A cut-off wall should be constructed above the heel or upstream face of the new section, and should be carried from 15 to 30 feet in depth, according to the effective- ness of the grouting work. Unless the grouting work is found thoroughly effective, a cut-off wall of at least 10 feet in depth should be constructed along the heel of the old section. B. Leaks Under the New Section. These leaks may be stopped by the work above outlined on the dam foundation. If not they must be shut off by still deeper 30 Report on the Dam at Austin, Texas. and more thorough grouting at and immediately adjoining the fissures where the leaks now appear. In any event, the fissures should be well filled with grout, mor- tar or concrete. C. Improvements Below Toe of Dam. The depression below the toe of the new section must be filled with concrete which must be brought to an elevation above the footing of the cross walls of the dam in such manner as to give them a substan- tial bearing and resistance against sliding. This apron should be sufficiently heavy to prevent further scouring by flood waters and should extend downstream to the rock ledge on which the mass of debris now lies. A fifty-foot apron in front of the old section is considered desirable, but possibly not essential at the present time if the bottom is watched and repaired whenever in- dications of any erosion by the flood waters appear. Weep holes should be pro- vided through all aprons to prevent uplift pressure from springs or seepage waters. 2. Dam Structure A. Crest of Dam. The crest piers and gates on the dam should be removed and the crest of the reinforced concrete structure brought to the same elevation as the crest of the old structure. B. Old Dam Section. The foundation and structure of the old dam should be filled with cement grout and the section should be reinforced with concrete, essen- tially as shown in Appendix 8, page 183. C. Reduction in Seepage Around Dam. The rock bluff west of the dam should be grouted to reduce or prevent seepage. Excavations should be made along the east bluff where leakage is known to occur, and all the cavities should be properly filled and sealed. A careful examination should be made of the pervious strata in which these leaks occur, and if further work in reducing the leakage seems feasible it should be undertaken. D. Walk in Dam. A reinforced concrete walk should be constructed to replace the wooden walk in the old dam and the railing should be cleaned from rust and thoroughly painted. E. Sluice Gates and Sluiceways. The sluice gates should be rebuilt or repaired in a substantial and permanent manner. The sluiceway should be strengthened where necessary and the one which has not been repaired should be repaired in a substantial manner. F. Inspection of Foundation Under Dam. During the construction of the apron, the inside of the hollow dam should be cleaned out and the bottom carefully exam- ined for signs of additional leaks. 3. Plant Accessories A. Head Gate Masonry. The head gate masonry should be grouted, pointed and rendered essentially water tight. B. Head Gate Trash Racks. The head gate trash racks should be rebuilt so that the openings shall be from iy 2 to 1% inches in width, and the rack supports should be strengthened if found necessary. Estimated Cost of Improvements. 31 C. Tailrace. The pile of debris between the tailrace and the old dam should be removed, the tail race cleaned, and sufficient rock excavated to give the waters from the draft tubes a free discharge and a maximum velocity of not more than three feet per second. D. Defecting Wall. A deflecting wall should be built to protect the draft tubes from floating drift. E. Railing. A railing should be constructed from the face of the old dam down the abutment and along the retaining wall to the station building to protect the pub- lie. ESTIMATED COST OF BETTERMENTS, CHANGES AND IMPROVEMENTS The following is a summary of the writer's estimate of the cost of the better- ments previously recommended: Foundation Grouting and Cut-off Wall: Grouting, 25,000 ft. of drilling holes at $3 per ft $75,000 Cut-Off Wall New Dam, 5 ft. wide 30 ft. deep Excavation 3500 cu. yds. at $3 $10,500 Concrete 3500 cu. yds. at $7 24,500 35.000 Old Dam, 3 ft. wide 10 ft. deep 10,000 Apron for Dam, 12,000 cu. yds. at $7 84,000 Cofferdam 50,000 Crest of Dam, Removing Crest Pier $10,000 1,650 cu. yds. Concrete at $20 33,000 140,000 Ibs. Steel at 7c 10,000 53,000 Reduction of Seepage around Dam 25,000 Improving Old Dam Section 550 ft. at $210 per ft 115,500 Tailrace, Removal of Debris and Deepening Raceway 15,000 Deflecting Wall, 180 yds. at $12 2,200 Head Gate Racks, Reconstruction 300 Concrete Walk in Old Dam 2,000 Repairs to Sluice Gates and Sluiceways 10,000 Railing along Retaining Wall 100 Cleaning and Inspecting Rock Floor of New Dam 400 $477,500 Engineering and Contingencies and Misc. Expense 20 per cent 95,500 Total $573,000 32 Report on the Dam at Austin, Texas. CHARACTER OF THE ESTIMATE In considering the above estimate it is obvious that there are many uncertainties concerning the costs of some of these items. The structures are built and parts of them are inaccessible ; their conditions have been judged from the descriptions of others and from soundings of the rock bottom now concealed by water and debris. The pervious rock strata along the east bluff are also largely concealed by earth. The expense which will be involved where such contingencies exist has been cov- ered by liberal estimates. A contingent item has been added to care for extraordi- nary conditions of strata, floods, etc., and for other betterments which may be found necessary when an attempt is made to put the plant into operation. I believe that the estimates will cover the necessary expense involved in the construction of these betterments, and it is quite possible that a substantial saving may be effected if con- ditions are favorable. I do not believe, however, that it is safe to estimate the work on any lower basis. PERMANENCY OF THE STRUCTURES I have been instructed to report on the " permanency of the structures for all probable time and suggest such additional things, if any, proper to be done to make such structures permanent, stable and efficient." I have previously outlined various improvements and betterments which I be- lieve will render the work permanent, safe, substantial and fit for the service of the City, provided the execution of the work is thoroughly and conscientiously done. A detailed analysis of the stresses in the reinforced concrete dam shows that the structure is safe. The maximum stresses in the steel reinforcement are somewhat greater than good practice would warrant, reaching as high as 23,000 pounds per square inch instead of 16,500 pounds which was said (see page 134) to have been the basis of design. Considering the character of reinforcing steel, this stress is not so great as to lead to any fear of rupture. I believe, however, that a solid dam would have been a safer though probably a more expensive structure. Many high reinforced concrete dams are in use at the present day, though it still remains to be seen how permanent they will be after long years of service. The dam will, in my opinion, fulfill its functions for more than 25 years and may ultimately show that the econo- mies resulting from such a type of design are warranted. There are two risks involved in this project on which I am unable to give full assurance : 1st. Will the leakage around and under the dam greatly exceed the esti- mate of this report? If the estimated leakage is exceeded, the power estimate will be too high, and this value of the power which can be generated will be reduced unless the leakage can be partially or wholly eliminated. Permanency of the Structures. 33 2d. Will deep leakage under the dam endanger that structure? The fact that the old dam stood from 1893 to 1900 without developing serious deep leakage and finally went out from entirely different reasons, is a fair measure of safety, and I am of the opinion that with the precautions suggested the dam will remain a safe and substantial structure. I believe if the betterments outlined are carried out with proper care, the risk involved in the permanency of the structure will be small. I would advise, how- ever, that after these betterments are completed and the plant is placed in opera- tion, the City have an examination of this structure made annually by an engineer experienced in the construction of dams, in order to detect and remedy any defects which may possibly develop. Value of Material and Labor in Place. The material and labor in place have been estimated on the basis of prices prevailing at the time the structures were under construction. These estimates are discussed and shown in detail in Appendix 9. They are here summarized as follows: Reservoir $43,650 Power House, Penstocks, Pole Lines, etc 37,773 Machinery and Equipment 99,624 Dam 491,660 Extras 13,792 Total $686,499 In accordance with instructions contained in a letter from Mayor Wooldridge dated September 14, 1917 (see page 4). I have given thoughtful consideration to the matter of responsibility for the cost of the betterments necessary to make this dam a safe, stable and useful structure. Such a division of responsibility is desirable if possible but such limits are diffi- cult to fix. The exact line between safety and danger is indefinite. No one can say that if a certain definite number of dollars are spent on these betterments safety will be assured, that if a few dollars less are spent the dam will be in danger, and that if a few dollars additional are expended the money will be wasted. In the construc- tion of a dam, in order to be safe the design must carry the structure well beyond the lines of danger and well within the zone of safety in order to provide for those unknown factors which must always be anticipated in engineering works. It is therefore somewhat difficult to separate the responsibility for additional work called for or fairly implied by the terms of this contract from these things which must be done yet are not specified in the contract which contains a specific guarantee for 25 years maintenance. In such analysis the meaning and intent of the contract are fully as important as the written word. 34 Report on the Dam at Austin, Texas. The City of Austin elected to pay a second party a fixed sum plus an annual rental, to do the work and to assume the responsibility of both constructing and maintaining this dam for a period of 25 years. This plan seemed plausible and proper guarantees seemed feasible, and the plan was legalized by an act of the Leg- islature specifically authorizing this form of contract. The City failed to see that the responsibility of the promoter was the only ele- ment that gave the guarantees value, and that the only factors which would render the guarantees of the promoting company of real worth were: 1st. The money which the City itself must pay to this Company. 2d. The success of the plans which the promoters might elect to carry out. 3d. The money which the promoters might borrow through the faith of in- nocent parties in the validity of the contract and on the standing of the City of Austin. As a matter of fact, if the promoters failed to complete the work the City was out nothing, but the burden was shifted not to the shoulders of the promoters but to the shoulders of their creditors. The promoters on their part had nothing to lose and everything to gain. They did not propose to put their own money into the venture but to carry their endeavor on borrowed capital, and to shift the risk which they ap- parently assumed, on innocent parties who had no means of knowing or appreciating the risks involved. These promoters proposed to the City of Austin to construct certain works for payments having an aggregate present value of a million dollars, and they hoped to secure a return of one-half this amount for promoting and financing the scheme. They attempted to build for less than $500,000 structures which could not be built properly and safely under the conditions which obtained during the period of con- struction, for less than the entire million dollars involved in their contract. The City fixed its faith on guarantees which were elaborately described in the franchise ordinance but were, under the circumstances and for the purpose of se- curing satisfactory construction, the least essential feature of a contract. The pro- moters furnished incomplete plans and indefinite specifications, and rendered them both even more uncertain by the provision that their Engineer could modify them at his will provided that he did not l ' decrease the amount of equipment in the power house, the height or stability of the dam, the size of the reservoir, or in any wav diminish the capacity or completeness of the installation or in any way lower the standard or grade of construction." Having secured the contract, the promoters immediately began work in order to fulfill the required terms of progress. A stock company was organized for financ- ing the proposition, to which the franchise was assigned and by which means all individual responsibility was avoided. A contractor was induced to undertake the work for a fixed sum, with a provision that if any reduction in the cost of the work was possible, two-thirds of the saving would be credited to the promoting company. Responsibility for Cost of Improvements. 35 Every effort seems to have been made to reduce the cost of every feature of the work to the utmost. The City apparently approved these vague and imperfect plans and specifica- tions solely on the basis of valueless guarantees, and appointed an Engineer who apparently approved the construction on the same basis. The City naturally has re- fused the acceptance of the work because these guarantees have not been fulfilled. There has been expended on this work about $750,000, or more than 50 per cent, in excess of the cost for which the promoters expected to construct it. To put the work into safe condition so that it will successfully perform the functions for which it is intended will cost still more than the promoters ' original estimate for the cost of the entire work. Grouting and cut-off walls were required by the contract. The cut-off walls were eliminated and the grouting might almost as well have been omitted so far as results are concerned, for the work done was entirely insignificant in view of the amount of such work required for safety. The promoters assumed responsibility for those portions of the old dam which they proposed to utilize, although they knew that conditions might arise under which it would be unstable. In the original report of their Engineer the statement was made that: "The dam therefore will require some additional masonry. This is simply to assure beyond any possible doubt stability under any flood that may ever come down the river. The dam may be looked on as reasonably safe as it now stands. ' ' Their Engineer advised that: ' ; The section of the old dam should be strengthened by the addition of a mass of concrete well bonded in the granite of the structure. ' ' No such improvement was provided in the plans submitted to the City of Aus- tin, and even the cut-off wall planned at the heel was omitted. It is my opinion that the old structure is unsafe as it now stands and that unless radical changes are made it will be destroyed in less than 25 years unless it is again relieved from danger by the destruction of the new section which is liable to early failure unless its foun- dation is rendered stable and impervious. No provision was made in the specifications for an apron below the toe of the dam. It was known that a deep trench had been formed along this toe by flood waters and that the trench was largely responsible for the destruction of the dam in 1900. The cross walls of the new structure were apparently carried into fairly substan- tial material yet the average depth of these foundations was left considerably above the old trench which lies immediately below them. The condition creates a real danger of the new structure sliding on the underlying strata ; and even if it be found by experience that the conditions have a slight balance of safety, the frequently re- 36 Report on the Dam at Austin, Texas. curring floods will deepen this channel, undermine the structure, and ultimately de- stroy it. This condition needs an immediate remedy, and no engineer of experience would consider the structure safe at the present time ivith the conditions as they now exist. The expense of such betterments as described above is essential for the safety of the structure. In view of the guarantees they cannot be avoided on the grounds that they were not specified. For an apron below the old structure, the necessity is not so imperative. An apron for this portion of the work, if the dam is otherwise properly strengthened, is a matter of extra precaution and is not immediately needed for safety provided the toe is carefully watched and repairs are made as soon as their necessity is indicated. Under the contract the responsibility for this betterment may fairly be said to be with the City. I believe that the large expense involved in the construction and maintenance of proper gates is unnecessary and undesirable. This expense is unwarranted by the additional power which would theoretically be developed ; and the increased leak- age, the additional evaporation and the extra stress in the structure which would be caused by the additional head, still further reduce the desirability of gates. The loss due to their elimination can be at least partially regained by a reduction in leak- age through the pervious strata above the dam ; and while the cost of reducing leak- age except that "immediately" around the old dam is eliminated by the specifica- tion, the cost of this work and the expense of raising the crest of the new section to that of the old dam is an inconsiderable substitute for the cost of the installation of proper gates and their expensive maintenance. The work on the tail race has not been properly performed and the expense in- volved in this work is obviously required by the contract. The draft tubes should not have been constructed in their exposed position. The deflecting wall to protect these draft tubes is therefore fairly chargeable under the contract. The head gate trash racks were rebuilt, I understand, on the design of the City 's Engineer and according to his instructions, and the reconstruction is justly charge- able to the City. The timber walkway inside of the old dam would have to be maintained for 25 years, and its reconstruction in permanent concrete is an economy fairly chargeable to the promoters. The repairs to the sluice gates and sluiceways and the construction of sluice gate trash racks are made necessary by faulty design and neglect, and these appurten- ances even when repaired will not be in a satisfactory condition. The expense of placing them in a condition in which they should originally have been constructed is prohibitive and is not advised. Responsibility for Cost of Improvements. 37 The railing along the retaining wall is not required for the safety of the struc- ture and should be built by the City for the safety of the citizens. It is my opinion that with the exception of the few minor items specifically men- tioned, the cost of the betterments recommended should fairly be paid by the pro- moting company under its guarantee to build this dam and maintain it for 25 years. Such a finding, however, seems absurd where the facts are recognized that the officials of the promoting company have realized their failure and have abandoned the work which is now in the hands of a receiver. Under the conditions that now obtain these promoters have apparently no legal responsibility and they certainly have few rights in equity which the City is bound to respect. The promoters, however, transferred their financial responsibility to the shoulders of their creditors. The creditors consist of the assignee of the Contractor who performed the work for the Promoters, of the holders of the bonds issued by the Promoting Company, and possibly of some other legitimate claimants. On the basis of a moderate prospective profit, the Contracting Company took a contract for the performance of certain specific things which the City had approved as sufficient for the purpose, and in their contract specifically disclaimed any respon- sibility for the plans involved. The work done is apparently first class in every particular, so far as the limits of the defective plans and specifications provide. The difficulties that have arisen and the defects that have developed are not those caused by defective work but were caused by defective or deficient design, for which the Con- tractor is in no way responsible in equity although it may be in law. The bond holders who purchased the bonds issued by the Promoting Company are in equity even less responsible. They purchased bonds on their faith in the City of Austin and on the franchise, specifications and plans which the City of Austin had approved and accepted. These innocent parties, drawn into unfortunate legal complications through the efforts of promoters to secure undue profits, are worthy of the fairest consideration. As the enterprise now stands, the interests involved are as follows: 1st. The City Water Power Company, bankrupt with apparently no assets except a franchise, is in the hands of a receiver. 2d. The Wm. P. Carmichael Company with about $500,000 invested, has apparently already expended $250,000 in excess of its claim and is in the hands of its creditors. 3d. The creditors of the Wm. P. Carmichael Company. 4th. The purchasers of the bonds of the City Water Power Company. 5th. Certain creditors who hold claims directly against the City Water Power Company. 6th. The City of Austin which for almost thirty years had endeavored to con- summate this project. 38 Report on the Dam at Austin, Texas. Only the abandoned site and station of the City of Austin are invested in this en- terprise, with the exception of the $21,000 advanced the Contractor, which is less than half the value of the water works reservoir, completed in 1912, and used by the City for the last five years. The City, however, holds the key to the situation and has a moral if not a legal obligation to effect some arrangement whereby the situation can be cleared up and the endeavor carried to a successful consummation with the least possible injury to all concerned. From my study of this unfortunate situation I believe the only practicable, legal and equitable way for a fair adjustment of the cost of the necessary betterments for this work and of the interests involved in this property is for the City to take over the property on some fair and equitable basis and : 1. Either make a new contract with the creditors who have valid claims against the work, on a basis which will enable them to finance the cost of better- ments and ultimately recover their present and additional investment; 2. Or for the City to undertake these betterments at its own expense, pay- ing to the legitimate creditors possibly in annual installments, a fair valuation for the work already done. The water power property as it stood without reconstruction was valueless. While the cost of the necessary betterments is large, it is not more than half the legi- timate cost of a proper reconstruction of the property as it stood in 1910 ; and the cost of these betterments if added to the legitimate outlays that have been made under the Johnson contract, will be more than warranted by the value of the prop- erty to the City. ULTIMATE VALUE OF THE PLANT As a basis for the annual payments on the Johnson contract, the value of the hydraulic power to be delivered from the reconstructed plant was evidently esti- mated at 0.9c per horse power hour, as the amount of the minimum power (600,000 HPH per month) would on that basis equal the amount of the annual payments of $64,800 per year. It is not probable that the saving effected by the annual amount of power used will equal this amount at the present time, as the cost of operation and maintenance of the hydraulic plant must be paid by the City and the saving at the steam plant will include only the cost of fuel, certain labor and certain incidental ex- penses. However, taking into consideration the fact that there would be additional power besides the minimum, which could promptly be utilized to secure additional in- come, and that the payment made will ultimately result in the acquisition of the plant by the City, this annual payment would be entirely warranted. Furthermore, as the amount of the power demand increases, the cost per unit output will decrease, and with the rise in the cost of fuel the ultimate value of the horse power hour of Responsibility for Cost of Improvements. 39 hydraulic power compared with the cost of generating power by steam, may very properly be estimated at .9c per horse power hour. On this basis the average annual value of the power available when the plant is fully utilized is, on the basis of a 60-foot head, equal to approximately $190,000. This capitalized on a 10 per cent, basis, to cover interest and depreciation, will give an ultimate value to the installation of approximately $1,900,000, which is a fair measure of the maximum amount which ultimately could reasonably be expended in the con- struction of this plant. t SUPERVISION OF THE CONSTRUCTION OF BETTERMENTS The proper construction of the betterments recommended in this report is just as essential as the betterments themselves, and without proper workmanship the en- tire amounts estimated may be expended and the dam remain unsafe. No ambition for authority, no political interference, no desire for profit must be allowed to in- terfere with thorough, first class work. The work should be intrusted to some one who has had extended practical experience along such lines of work, and he should be given such authority as will enable him to complete the work in a thorough and workmanlike manner. If uncertainties arise in regard to any matter or thing con- nected with the work, engineers having special experience should be consulted, for the saving thus affected and the security thus gained will be large. The City ought not to run further risks in the matter of safety or permanency for lack of sound pro- fessional advice. APPENDIX 1 HISTORY OP THE AUSTIN, TEXAS, DAM For a full understanding of the present (1917) problem of the Austin dam, and in order to emphasize certain important conditions in relation thereto, it seems es- sential to review briefly the history of the endeavor to develop power by the construc- tion of a dam across the Colorado River at Austin, Texas. As early as January 4, 1839, the water power possibilities of the Colorado River at Austin were pointed out by the Commissioners for the location of a permanent site for the Capital of the Republic of Texas. In 1871, Mayor John W. Glenn had surveys made above and below Mt. Bonnell to determine the possibilities of developingwater power. In 1873, a charter was granted to Judge John Hancock and others authorizing the erection of a dam across the Colorado River at Austin, which was, however, al- lowed to lapse. In 1876, an offer from an Eastern capitalist to build a dam just below Mt. Bon- nell was refused by Mr. P. C. Taylor, owner of the property. In 1887, Captain W. C. Walsh called attention, in a letter to the "Statesman" of the possibilities of irrigation from the Colorado River by the construction of a dam. On January 1, 1888, Mr. A. P. Wooldridge (now mayor) advocated the construc- tion of a dam in a communication to the Board of Trade of Austin. The Board of Trade, after due consideration, engaged Mr. John F. Pope to make a survey and report on the practicability of the project. Mr. Pope, after an examination and in- vestigation, reported in favor of such a project and his report was referred to a Com- mittee composed of Mr. John McDonald and Captain W. C. Walsh, who reviewed it and submitted estimates of the cost of construction. The feasibility of the project was urged by Mr. Wooldridge and Mr. John McDonald, the latter running for Mayor in the fall of 1899 on that issue and being elected by a large majority, to- gether with a Board of Aldermen favorable to the enterprise. BEGINNING OF ACTIVE WORK In February 1890, an appropriation was made for an investigation of this pro- ject, and Mr. Jos. P. Frizell, a hydraulic engineer of Boston, was employed for this purpose. On March 26, 1890, Mr. Frizell submitted a report recommending the con- struction of a 60-foot masonry dam. Beginning of Active Work. 41 There were practically no hydrographic data of the stream flow of the Colorado Eiver available at that time. The recollection of the oldest inhabitant established an extreme flood height above low water in the river, of 45 feet, which Mr. Frizell es- timated as probably equal to 250,000 cubic feet per second and which he found would produce a depth of 16 feet on the crest of the proposed dam. Mr. Frizell assumed that the flow of the Colorado Eiver was : ' * Wholly maintained by springs, issuing from cavities in the rock and is un- affected by current rainfall until the latter becomes sufficient to cause a flow from the ground. This is the present condition and I conclude we shall not be far wrong in taking the present flow of the stream as the quantity that can be de- pended upon. This, as I have ascertained by careful measurements, is nearly 1000 cubic feet per second. There will no doubt be times during the hottest weather when the water will fall below this stage on account of increased eva- poration. I am told however that a month very rarely passes without rains in some part of the drainage basin sufficient to cause a slight rise at Austin. "The great extent of the pond will enable a considerable deficiency in the flow of the stream to be made good by storage. From the best information I can obtain, the pond will extend some 30 to 35 miles from the dam, with an average width of 14 of a mile, containing a water surface of some 8 square miles and a total volume of something like 2,800,000,000 cubic feet of water. Should the flow of the stream diminish to y 2 of the above quantity, a single foot in depth on the pond will make good the deficiency for a period of five days, and 6 feet will make it good for thirty days. ' ' Mr. Frizell also calls attention to the possible use of 4-foot flashboards for addi- tional storage, estimates the average working head from the proposed dam at 57^ feet, and calculates that at 80 per cent, efficiency 5,227 HP could be delivered contin- uously. On the basis of concentrating the entire weekly flow of the stream into a working week of 60 hours, he calculated the available power at 14,656 HP. His es- timate of the cost of the entire endeavor, including the dam, power house, water works system, electric light system and equipment, was $1,362,781. The general scheme was approved by Mr. John Bogart, Consulting Engineer of New York. Soon after the submission of this report, an engineering party surveyed the flowage above the proposed dam site and determined that the pond would extend 22 miles above the dam. Bids for the proposed issue of bonds and for the construc- tion of the dam were received on October 15, 1890, and the bid of Mr. Bernard Cor- rigan, of $501,151 being the lowest for the construction of the dam and the excava- tion of the canal was accepted, and a contract was duly entered into. Excavation for the foundation of the dam began on November 5, 1890, and the first stone was laid in the dam on May 5, 1891. The work was delayed to some ex- tent by the floods of the river, but the last stone in the dam was laid on May 2, 1893. The upper and lower faces and the dam crest were of red granite from Granite Moun- tain. The interior of the dam was of the hardest local limestone rubble. All mas- 42 Report on the Dam at Austin, Texas. onry was laid in Portland cement. The total amount paid to Mr. Corrigan, under his contract, including extras, was $627,927.90. The general scheme of development as planned by Mr. Frizell, is shown in Fig. 13. CHANGE IN PLANS Early in the year 1892, a serious difference of opinion arose between some of the Board of Public Works and Mr. Frizell, concerning the location of the power house (which Mr. Frizell had planned to place some 600 feet below the dam) and the method of conducting the water to the power house, which Mr. Frizell had pro- posed to accomplish through an open canal. The Board was of the opinion that a Hews. FIGUKE 13 Plan, Profile and Cross Section of Austin Dam as Originally Designed. J. P. Frizell, En- gineer; John Bogart, Consulting Engineer. (Eng. News, July 11, 1891.) safer location would be on the rock ledge below the dam, and that the water should be conducted to the power house by iron penstocks instead of through an open canal. In January, 1892, Mr. E. C. Geyelin was employed to report on this matter. His report was made on February 17, 1892, and the changes in plans suggested were advised. These changes were opposed by Mr. Frizell, and the Board finally em- ployed Mr. J. T. Fanning of Minneapolis to pass on these matters. On June 24, Mr. Fanning submitted his report, recommending the change in the location of the power house and the use of penstocks instead of an open canal. He also advised a change in the form of the crest of the dam to that shown in Fig. 19, page 49. Mr. Fanning was retained as Consulting, and Mr. Frizell resigned his position as Chief Engineer on June 30, 1892. Mr. E. W. Groves, who had been Assistant Engi- neer to Mr. Frizell since the work started, was appointed Engineer in Charge of Con- struction of the Dam. At this time the foundation was in place and the masonry work above in progress. Change in Plans. 43 The dam was built on the rock bed of an ancient and greater river than the present Colorado. The shores of the ancient stream were rock and nearly vertical. The mod- ern Colorado occupied less than half of the ancient rock channel at this point, and the remainder of the old channel, including more than its east half, was filled with an al- luvial deposit 40 feet or more in depth. A narrow cut was made through this deposit rC!i.rrmc. RECORD FIGURE 14 A. Plan of Original Penstocks and Power House, J. T. Fanning Consulting Engineer. (Bng. News Jan. 26, 1893.) B. Section of Original Power House, J. T. Fanning, Consulting Engineer. (Eng. Rec. July 1, 1983.) 44 Report on the Dam at Austin, Texas. to the east shore for the purpose of construction of the foundation of the dam. (See Fig. 15, page 45, also Fig. 16, page 45.) Mr. Groves stated (see Engineering News May 3, 1900, page 290) that the rock was good for about 150 feet from the east bluff at which point a fault was encountered which extended about 75 feet. The rock, however, was found to be poor for about 350 feet farther, when it began to improve, and under the west portion of the dam the rock was good. He further says : ' ' In the fault there is no semblance of stratified rock except occasionally a de- tached piece. Most of the material was adobe or pulverized rock with an occa- sional streak of red clay. The excavation at this place * : * was carried down 8 to 10 feet in the upstream trench, and the trench widened to 10 feet or 15 feet, the fault extending down indefinitely. ' ' The foundation was not only poor, but the conditions evidently made proper work difficult. Mr. Groves (see Eng. News, Jan. 26, 1893, page 87) described the founda- tion work as follows : "During the laying of the foundation considerable water was encountered, the excavation in places being carried 11 feet below low water in the river to get to solid rock. Two 6" discharge centrifugal pumps were used to keep the foun- dation dry, but in places where it was impossible to get to the bottom of the trench in good condition to bed stone properly, concrete was used to lead up above the water. Strong flowing springs were encountered in various parts of the foundation which gave considerable trouble until wrought iron pipes were made use of. The water from the springs was conducted to the pumps through pipes of suitable size, the pipes being covered with masonry, and the springs sur- rounded by a wall of masonry well built. After the mortar had thoroughly set, this wall would be filled with rich concrete and no more trouble would be exper- ienced from that spring. The end of the pipe was stopped with a plug or iron cap. ' ' DATA OF THE COMPLETED DAM The data for the dam as completed were summarized by Mr. E. W. Groves, As- sistant Engineer, as follows: Length of Spillway 1,125 ft. Length of Dam, including Bulkhead 1,275 ft. Height above Low Water 60 ft. Maximum height above Foundation 68 ft. Width of Base 66 ft. Power Available (60 hrs. per week) 14,500 HP Minimum Flow 1,000 cu. ft. sec. Maximum Flow 250,000 cu. ft. sec. Drainage Area above Dam 50,000 sq. mi. Length of Lake formed 25 miles Area of Lake 2,000 acres Construction of Original Dam. 45 FIGURE 15 Construction of Original Dam at Austin, Texas, Showing Narrow Trenches on the East Side of the River, in which the Dam was Constructed. (Bng. News Jan. 26, 1893.) FIGURE 16 Headgate Masonry in Process of Construction at East End of Dam, Jan. 4, 1893. Also show- ing Narrow Trench in which Dam was Constructed. (Eng. News Jan. 26, 1893.) 46 " '; ^2$"*,**Jo ," o* * Report on the Dam at Austin, Texas. FIGURE 17 Break under Headgates, Austin, Texas May 30, 1893. (Eng. News July 27, 1893.) M L H SECTION X-Y FIGURE 18 Plan and Section Showing Leaks at Austin Dam prior to 1900. (Eng. News Feb. 22, 1900.) Leaks in the Foundation. 47 Masonry in Dam 95,000 cu. yds. Minimum Size of Granite used 93.5 cu. ft. DEVELOPMENT or LEAKS IN THE FOUNDATION The weakness of the east portion of the foundation was recognized and clay was dumped against the upstream face to prevent the seepage of water under the struc- ture. Soon after the dam was completed, springs were discovered just below the toe and opposite the weak portion of the foundation. (See letter from E. W. Groves, Eng. News, May 3, 1900, page 290.) On September 2, 1892, a contract was entered into with Mr. James Waterson for the construction of the head gate masonry, and this work was finished on May 12, 1893. On January 20, 1893, a contract was made with Waterson & Wattinger for building the power house foundations. This work was completed the following March. On the 30th of May, 1893, a break occurred about 75 feet above the head gate masonry and the water passed down to a depth of about 25 feet below the mas- onry and out through a soft stratum of rock into the excavation of the power house, causing a portion of the head gate masonry to settle, and overturning a part of the power house foundation. (See Fig. 17, page 46.) The cause of this break was a layer of loose material in the rock below the foun- dation of the head gate masonry. As the water was raised in the pond above the dam, it found access to this seam and washed out the sand or clay which it contained, causing a settlement of the foundation. The head gate masonry cracked about 40 feet from the end of the dam along the line H M, shown in Fig. 18, page 46, and settled. The earth east of the east end of the head gates settled for a distance of 25 feet. A cofferdam was built from the east end of the dam to the river bank, about 125 feet above the head gate masonry, and the flow of the water thus stopped. The broken part of the head gate masonry was removed, leaving only that portion over penstocks 1 and 2 ; and an excavation nearly 200 feet long and 70 feet deep, with an average width of 7 feet, was made. This trench reached to a level of 57 feet below the crest of the dam or within 3 feet of the level of the toe. The head gate masonry was rebuilt, the excavation beyond the penstocks being filled by a concrete wall 112 feet long which was 8 feet thick for the 90 feet next to the head gates, and 5 feet thick for the rest of the distance. In excavating for this extension wall, alternate layers of hard and soft limestone were encountered. The bottom layer of the concrete filling was laid on one of these layers of strata, but it was fully demonstrated that a current of water was running underneath. Several holes were drilled in which the water rose in jets several in- ches high ; however, it was thought safe to plug these holes and to ignore the stream below. (See Bui. 164, Univ. of Texas, by T. U. Taylor, page 31.) 48 Report on the Dam at Austin, Texas. The bulkhead masonry originally extended to the level RS (see Fig. 18, page 46) or 36 feet below the top of the dam; but as an extra precaution a tunnel ESTU, 6 feet square and 60 feet long, was cut under the bulkhead masonry back to the end of the dam proper, and this space was filled with concrete. The space below the 42 foot level under the tunnel was not disturbed. Apparently there had been considerable interference by the Mayor, who was also Chairman of the Board of Public Works, with the plans of the Engineers both before and after the resignation of Mr. Frizell. Both the Resident Engineer, Mr. Weren- skold, and the Contractor for the head gates, Mr. Waterson, had been ordered (in Nov. 1892) by the Board to follow the instructions of the Mayor (see Eng. News, June 29, 1893, p. 619), and this constant interference led to the resignation of the Engineer in Charge, Mr. E. W. Groves, in the spring of 1893. (See Eng. News, July 27, 1893, p. 78). This interference seems from the evidence to have been large- ly accountable for the imperfect work at the head gates. After the completion of the new headworks, the foundation for the power house was excavated to a depth of more than 80 feet below the crest of the dam. Due to the excess of water encountered, the original contractors threw up the work, and the new contractors succeeded in controlling the flow of water through the rock by con- structing a cement chamber at D (see Fig. 18, page 46) with a 10" horizontal pipe outlet which projects through the wall of the power house at the point C, about 54 feet south of the crest of the dam. (See also Fig. 21, page 51.) This water undoubtedly flowed under the head gate foundation, coming indi- rectly from the lake above the dam. Measurements taken in October, 1895, showed a discharge from this pipe of 4.6 cubic feet per second. WAKNINGS OF DISASTEK On April 8, 1896, Mr. J. P. Frizell wrote Mayor Hancock of Austin, in part as follows (see Eng. News. Apr. 1900, p. 252) : ' ' In laying the foundation of the dam at Austin, a very friable foundation of rock was met with some 300 or 400 feet from the eastern end ; in fact, the rock was poor for the entire easterly half of the dam. I was apprehensive that danger- ous abrasion might occur here in future, but as this part at the time was over- hung by a bank of earth 40 or 50 feet high, my plan was to wait until the bank had disappeared, as it might be expected to do on completion of the dam, and then to execute some supplementary work of protection. * : "My purpose in writing is to suggest that you cause soundings to be made along the toe of the dam to ascertain if dangerous abrasion is in progress in that locality." In 1897, Mr. G. H. Palm of Austin, while fishing along the toe of the dam ran his fishing pole under the toe for a distance of 6 feet, showing conclusively that undermin- ing had occurred over the weak strata where the dam finally gave way. (See B Fig. 19, page 49.) Silting of the Reservoir. 49 In 1899 a leak was also discovered at the point A (Fig. 18, page 46), near the east end of the dam, and was stopped by filling behind the dam at this point with clay, loose and in bags. While this filling was in progress, the water discharging from the 10" pipe almost ceased for a few hours, but soon reached its normal amount, being kept muddy while the fill was in progress. In the fall of 1899, water was noted disappearing at a point B (see Fig. 18, page 46) only a few feet from the shore. A cofferdam was constructed around this point A. B. FIGURE 19 Sections of Austin Dam. (A) as Constructed upon Recommendations of J. T. Fanning. (B) Showing Supposed Condition of Undercutting and Silt Deposit prior to Failure in 1900. (Eng. News May 10, 1900.) and afterwards filled with some difficulty with hay and earth. The location and method by which these latter two leaks were remedied are shown in Fig. 22, page 51. THE SILTING OF THE RESERVOIR In Water Supply and Irrigation Paper No. 40 on "The Austin Dam," Professor T. U. Taylor states that in 1890, cross sections of the Colorado River were taken at sixteen stations above the dam site. Cross sections were again taken by the United States Geological Survey in May, 1897 and in January, 1900. These sections and the silt deposit that had occurred between these dates at the various stations are shown in the diagrams on page 50. Between May 16, 1893, when the water first flowed over the dam, and May, 1897, 31,667,000 cubic yards of silt, occupying 38 per cent, of the original reservoir capacity, had been deposited. In January, 1900, this amount had been increased by 8,429,000 cubic yards, the total silt deposit then occupying 48 per cent, of the required reservoir volume. In January, 1900, fhe silt immediately above the dam had reached a depth of 28 feet or a level 38 feet below the crest of the dam (see B Fig. 19). Concerning the nature of the silt, Professor Taylor says: "In 1897 this silt, to within two miles of the head of the lake, was a fine, im- palpable, absolutely gritless deposit, and where newly exposed would not bear an appreciable weight on its surface. The writer has often tried its resistance all along the lake, and an oar could be driven into it several feet with moderate pres- 50 Report on the Dam at Austin, Texas. LOCALITY D/STANCE FRO DAM CLIFTON HARRISONS Bff HO HEY CREEK HUGHES SANTA MONICA SCOTT'S TOWER MCNEILLS LANE OGOfflTA DEVILS HOLLOW ENNIS FARM BULL CREEK DRY CREEH MORMON FALLS 500 460 650 ~''"<"f-ffffff-s+*' 76O 7QO 950 680 //BO /300 I7.4O " /S30 " I4-.60 " /3.7C " IQ.4O " 5.25 " 775 " TOO " 5.60 " 4.0O " 2.00 " I.ZO " 0.20 " FIGUBE 20 Cross Sections of Lake above Austin Dam showing Accumulation of Sedi- ment between 1893 and 1897 (Lower Shaded Area) and between 1897 and 1900 (Upper Shaded Area). Numbers above Sections indicate Length in Feet (Water Supply Paper No. 40 U. S. G. S.) Leaks in the Foundation. 51 FJGUBE 21 Leak under Headgates Discharging through 10-Inch Pipe in Foundation Wall prior to 1900. (Water Supply Paper No. 40. U. S. G. S.) FIGURE 22 Showing Location of, and Methods used to stop Leaks above Austin Dam prior to 1900. (Water Supply Paper No. 40 U. S. G. S.) 52 t on the Dam at Austin, Texas. FIGURE 23 Dam and Power Hou^e at Austin, Texas, prior to 1900. (Note Detritus below Dam.) FIGURE 24 Plan Showing Break in Original Austin Dam April 7, 1900. Eng. News Apr. 19, 1900.) The 1900 Failure. 53 sure. Shovelfuls of it placed upon boards in a heaped-up mess would immedi- ately settle and spread so that the upper surface was almost horizontal. ' ' It is evident from the above that the silt under water and in contact with the dam must have exerted a considerable extra pressure against that structure. THE 1900 FAILURE These various indications of weakness seemingly led to only temporary measures of repair and apparently no general investigation was made or radical betterments at- tempted. The rock below the eastern portion of the dam was covered with alluvium during the construction of the dam, and this was washed away by the occasional floods of the river after the dam was completed. The rock had therefore never been examined nor its condition ascertained. It was apparently, however, of the same friable nature as that in the foundation of the dam as described above. On this soft deposit was ex- pended the energy generated by the falling waters of the passing floods. While the change in the cross section of the dam was undoubtedly an improvement in the con- dition of hydraulic flow, yet the toe of the dam was too short to give flood flows a hori- zontal direction, and the tremendous energy developed by the falling waters (amount- ing to about 360,000 HP in the flood of 1900) was partially expended in tearing up and displacing these rocks and depositing them on a bar below (see Fig. 23, page 52), or washing them away ; at the same time the back current was undermining the struc- ture itself (see B Fig. 19, page 49). The discharge of the waters from the wheels along the toe of the dam developed velocities altogether too low to have had any serious ef- fect in eroding this rock, but the cross currents produced at times of flood by the pres- ence of the alluvial deposits in the old river channel below the eastern portion of the dam, may have added seriously to the erosion. On April 7, 1900, with the water 11 feet above the crest of the dam, the dam gave way at B (see Fig. 24, page 52) about 300 feet from the east end, and two sections, AB and BC, each about 250 feet long were shoved downstream a distance slightly greater than the width of the dam, into positions A'B' and B'C'. There was no overturning of the structure which held its section for some time after the break. The section B'C' finally disintegrated, falling upstream, and the eastern end of the section A'B' was soon after broken up and disappeared. The water from the dam broke through the windows of the power house, and later on the recession of the flood caused the north end of the power house walls to fall outward, taking with them the roof over the dynamo room and wrecking the corresponding part of the east wall. INVESTIGATIONS AND BEPORTS MADE AFTER THE 1900 FAILURE After the destruction of the dam various investigations and reports were made, and various projects considered for its reconstruction. On June 9, 1900, Professor T. U. Taylor of the University of Texas, made soundings, and ascertained the founda- tion course of the dam and several feet of the underlying rock has been washed out by the 1900 flood. (See Eng. News, Dec. 6, 1900, p. 390). 54 Report on the Dam at Austin, Texas. Later, an estimate on reconstruction was made by Mr. W. F. Foster to the City Government. This was followed, in 1905, by a report by Mr. Geo. E. Evans of Boston for the firm of Stone and Webster. FIGUBE 25 Location of Borings Made in 1907. 'ast_Portidn West Portion oTDam. FL Ffinf L&- Lime-stone /lard Limestone 3L5. Soft Limestone CHLS. Ctia/ty Limestone Cfiv. Cavities 20 40 60 iO 100 100 ca/ ScaJe -FECT- Horizontal Scale FIGURE 26 Rock Sections as Disclosed by Borings of 1907. In 1907, the Consolidated Construction Company was granted a franchise by the City Council to reconstruct and maintain a dam at or near the old site, to be paid for in 40 annual installments. Mr. Walter G. Kirkpatrick was retained and reported, in 1908, to the Water and Light Commission on the rebuilding of the dam. Under Mr. Kirkpatrick 's direction, 26 borings were made of the dam site under the imme- diate direction of Mr. A. C. Blanton. The locations of these borings are shown on Investigations after the 1900 Failure. 55 Fig. 25, and their depth and the general information disclosed are shown in Fig. 26, page 54. Of these borings Mr. Blanton says: "The stratification disclosed by the core borings was of alternate moder- ately hard limestone, soft adobe and cavities." These borings, he further states : 11 : * demonstrated indisputably the very undesirable condition existing at the site." See Eng. News, Apr. 22, 1915, page 78.) On account of the conditions developed, Mayor Maddox refused to sign the fran- chise ordinance of the Consolidated Construction Company, and arranged for a re- port by a Board of Engineers, consisting of Arthur P. Davis, Chief Engineer of the United States Reclamation Service, Louis C. Hill of the Reclamation Service, and Professor T. U. Taylor of the Engineering Department of the University of Texas. This Board, with the assistance of Dr. F. W. Simons, Professor of Geology in the University of Texas, inspected the series of borings above described, considered the geological formations both at the dam and at Mt. Bonnel, and recommended the con- struction of a new dam at Mt. Bonnel rather than at the old site, provided borings showed formations as favorable as surface conditions seemed to indicate. If, how- ever, the City decided to rebuild at the site of the old dam, this Board advised : 1st. That a deep curtain wall be constructed near the upstream face of the dam to cut off percolation under the dam so far as possible in order to reduce upward pressure to the minimum. This curtain wall they advised should be six feet in thick- ness and be connected by steel rods to the main dam. It should be carried to depths to be determined by local conditions as the work proceeded, but in general to a depth of 20 to 30 feet below the original foot of the dam and below any cavities disclosed by borings or otherwise. 2d. They further advised the increase in the mass of the dam in order to in- crease its resistance to sliding, the increase to be so located as to utilize the pressure of water on the dam so far as possible. 3d. They further advised that the foundation at the toe of the dam should be re- paired and extended by monolithic reinforced concrete to add to the resistance to sliding and to protect the toe from further erosion. 4th. They further advised the entire reconstruction of the east abutment and bulkhead walls, and that the body of the main portion of the dam which was to be re- placed should be built of concrete with granite facing on its lower slope and about 10 feet below the crest on the back of the dam. The cross sections proposed by this Board are shown in Fig. 27, page 56. On April 5, 1910, the City Council was authorized by a vote of the citizens of Austin to make a contract with Dumont-Holmes Steel Concrete Company to erect and maintain a dam 65 feet high above low water at the old site, which contract expired by limitation on January 23, 1911. 56 Report on the Dam at Austin, Texas. THE JOHNSON CONTRACT On September 11, 1911, a franchise was granted to William D. Johnson which pro- vided for the construction of a dam and power plant under conditions which are con- sidered in considerable detail in Appendix 2. - eefvf/es TO EXIST/MS Poerjotj OP OHM 110 /60 ISO I4O /JO no I/O 100 90 SO 70 60 SO 40 JO 20 10 90 SO 70 to so 40 30 20 IO New DGM IH BROKEN SFCTION - SECTION or* Peoooseo QlTE FIGURE 27 Cross Sections for the Austin Dam as Proposed by Messrs, Davis, Hill and Taylor, 1908. APPENDIX 2 CONTBACT OF WlLLIAM D. JOHNSON AND ASSIGNS FOE THE RECONSTRUCTION OF AUSTIN DAM AND POWEB PLANT As the purpose of this Report is an investigation of the reconstruction of the dam and power house under the above contract, and a determination of any changes that have been made from the requirements thereof, it becomes necessary to consider the ordinance, specifications and plans, which together constitute this contract. FRANCHISE ORDINANCE The ordinance is a document of some 24 sections, couched in the usual legal phraseology and which, for the purpose of a clear understanding, is here abstracted as follows : Section 1. William D. Johnson and his assigns are granted the right and fran- chise to erect a dam across the Colorado River at or near the location of the former dam. Such grant is for a period of two years for the purpose of construction, with such extensions as are made necessary by conditions beyond control, and for the ad- ditional period of 25 years from the date of completion. Section 2. Provides that Johnson shall have the use of all poles, wires and equip- ment on the lines between the original dam and the City power house, and all mater- ial contained in the original dam adjacent to the power house, for use in construction ; none of this material can be sold, however, until $25,000 has been expended on con- struction work. Section 3. The City of Austin leases, transfers and delivers to the said Johnson during the life of the ordinance all materials in the dam, headgates and power house, and all of its rights, titles and interest in the lands occupied by these structures, and all land owned by the City adjacent to the dam and downstream from a line 20 feet up- stream from the crest of the dam, together with all necessary flowage rights. Section 4. Grants Johnson the privilege to assign his rights to any person, firm or corporation, and the right to pledge, mortgage and assign to any trustee all of the rights, power and franchise granted. Section 5. Provides that Johnson shall indemnify the City of Austin against any damage to the property of the City and to hold the City harmless from any damage occasioned by any act or negligence of Johnson, his assigns or agents. Section 6. Provides that Johnson shall construct a dam, at or near the site of the dam formerly constructed by the City of Austin, in strict compliance with certain plans and specifications ; the said dam shall be five feet higher than the crest of the original dam and shall be fully equipped in accordance with said plans and specifica- 58 Report on the Dam at Austin, Texas. tions. The equipment shall include headgate masonry, head gates, forebay racks, flumes, turbines, draft tubes, and tail race. The said Johnson shall further supply the equipment of the power house, which shall include three vertical turbines of not less than 2400 horse power each when op- erating under a head of sixty feet ; three 6600 volts, 3-phase, 60-cycle electric genera- tors, to be directly connected to said three 2400 HP vertical turbines, and capable of generating not less than 6000 HP of electrical energy; two direct current exciting generators of such capacity that either one shall be able to furnish the necessary full load exciting current for all three of the 3-phase generators; two electric pumps, each of which, when pumps are working together, shall be capable of delivering 6,000,000 gallons of water per day of twenty- four hours or 12,000,000 gallons total for the two pumps, at a point two hundred and fifty-five feet higher than the crest of the original dam, through a 24-inch delivery main, and which pumps shall be con- nected to the water suction and delivery mains at the present City pumping station, the City to supply suction and delivery mains for said pumps, and to operate and maintain said pumps; a transmission line from the power house at the dam to the City's steam power plant, and a reservoir of ten million gallons capacity, to be lo- cated at such point as the City may direct. Section 7. Provides that Johnson shall begin actual work upon said dam within sixty days after the final passage of the ordinance, and shall have expended on con- struction, within 7 months from said date, the sum of $25,000 and shall have fully equipped and completed the dam and other work provided for, and shall have said dam and equipment ready for operation within two years from the date of the final passage of said ordinance; provided, that should any of said work be delayed by labor strikes, excessive floods or other causes not under the control of Johnson, an extension of time equal to the time lost by reason of any of the above causes shall be allowed. Section 8. Provides that Johnson shall deposit with the City of Austin the sum of $25,000, and deliver a full set of plans and specifications, which are to be held by the Mayor upon the following conditions: Johnson agrees to expend within 90 days after the date of the final passage of the ordinance, and within the next four succeeding 60-day periods, not less than $5,000 in each of said periods for material and work. If said amounts are not expended within the time specified, Johnson shall pay as liquidated damages to the City of Austin the sum of $5,000 for each period in which default has been made. If, however, John- son commences said work within 60 days, and complies with all the requirements, and expends $25,000 in actual work and material according to said plans and specifica- tions, within the 7 months next succeeding the passage of the ordinance, then the sum of $25,000 shall revert to and be paid by the City of Austin to Johnson. Section 9. Provides that Johnson shall prosecute work so that for each 60-day period, with the addition of such time as is herein provided for after the aforesaid 7 months, there shall be expended not less than $6,000 in labor and material under the terms of this ordinance until the completion of the concrete work on the dam. Franchise Ordinance. 59 Section 10. Provides that if defects develop in the dam, reservoir or other ap- purtenances, or in the power house flumes or tail race, that if leaks, seepage or other waste of water through, under or immediately around the end of the dam, headgate masonry or core wall occur, materially affecting the use of the water above the dam for power purposes, then the payment of the installments provided by the ordinance shall be suspended until repairs are made. That repairs shall be commenced at once and prosecuted diligently and be completed within a reasonable time, and shall under any circumstances be completed within 18 months from the date of written notice from the City of Austin demanding such repairs. That in the event of repairs not having been made within 18 months, the City at its option may discontinue payment of further installments or power rentals, and may terminate all privileges and fran- chises, and may take immediate possession of all work and material on the premises. Section 11. Provides that Johnson shall furnish the City all the water power of said dam and shall guarantee that two of the three generating units will continuously generate at least 3,300 HP of electrical energy; and Johnson further warrants that said machinery shall be sufficient to generate 600,000 HPH of electrical energy within any 30 consecutive days during the life of this contract. While the water is flowing over the crest of the dam, or has a level of one foot below the crest, the power will exceed the minimum named and need not be measured. When the water of the lake is reduced to a level one foot below the crest of the dam, which is called the deficiency period, the City shall measure the power used by it, and shall continue to measure same during the period when the water shall be below such level. The City may, dur- ing such period, use the water in the development of power at such times and in such quantities as it may choose, but shall not, without the consent of Johnson, reduce the level of the lake more than 18 feet below the crest of the dam. If during such period of less than 30 days, it should not be possible with the water power of the dam and with the machinery and equipment installed, to develop electrical energy at the rate of 600,000 HPH for each 30 days so measured without lowering the lake more than 18 feet below the crest of the dam, then for the difference between the amount which said Johnson binds himself to furnish at said rate of 600,000 HPH per 30-day period, and the amount actually furnished, the City shall make a charge of $.0135 per horse power hour against Johnson and assigns, and such amount shall be deducted from the next installment due from the City. Section 12. Provides that all power due the City shall be measured at the point where it is used, i. e. at the present power plant of the City or at any sub-station of said plant or at any pump installed at the dam. Section 13. Provides that the City shall control, operate and maintain all tur- bines, generators, machinery and apparatus in the power house at the dam, and the transmission line from the dam to the City's present steam power plant, and the elec- tric pumps to be installed in present City pumping station ; and the City shall have the right to change, substitute or add to said turbines, generators, machinery and ap- paratus, and that Johnson shall maintain and keep in repair the dam and its appur- 60 Report on the Dam at Austin, Texas. tenances, core wall, head gate masonry, head gates, flumes, draft tubes, reservoir and its appurtenances, power house, and the structural work of the tail race. Section 14. Provides that the City of Austin will pay Johnson or assigns one installment of $100,000 and 50 installments of $32,400 each; the first installment to be $100,000 due and payable upon full completion of the work, the starting of the plant and acceptance of same by the City; the next 50 installments of $32,400 each to be paid semi-annually, the first $32,400 installment to be due and payable 6 months after the completion and acceptance of said work, and the remaining installments to be due and payable one each 6 months thereafter until all are paid. Said installments to be paid from the gross earnings of the water, light and power plant of the City, and in no event are any taxes to be levied on the taxable property within the City for the purpose of paying any sum of money which may become due to Johnson and his assigns. Section 15. Provides that the City of Austin will, during the construction work, furnish Johnson the use of electrical energy up to 50 HP, or water of equivalent value. Any electrical energy or water of equivalent value in excess of said 50 HP, to be paid for at the current rates charged the City's regular consumers. Section 16. Provides that the City of Austin shall have the use of the water power developed by the dam and power equipment and shall at all times own and control the lake formed by the dam. Section 17. Provides that Johnson shall lay across the dam a 24-inch main as provided for in said plans if the City shall direct the construction of the reservoir on the west side of the Colorado Eiver. Section 18. Provides that at the expiration of the term of the franchise, the dam, its equipment and all the property embraced and comprehended in the ordi- nance, shall become the absolute property of the City. Section 19. Provides that the City may have access to the books and accounts of Johnson during the period of construction and that the City may appoint an en- gineer or inspector to see that all work done and material used are in strict accord- ance with the plans and specifications. Section 20. Provides that all notices to be given by the City to Johnson and assigns shall be sufficiently given by a simple statement in writing deposited in the post office of the City, addressed to the bank or other agent ; and during the term of construction, the engineer employed by the said Johnson in charge of said work, shall be the proper party to which any such notice shall be addressed. Section 21. Provides that in case of disagreement between the City and John- son, the same shall be left to arbitration by the selection of one party by the City and one party by Johnson, the two so selected to select a third party, and the judgment of the majority of the Committee so selected shall be considered as a final deter- mination. Franchise Ordinance. 61 Section 22. Provides that the City shall have the license and authority to use all parts, contrivances and devices used on the work, which may be covered by letters patent during the life of this contract and at all times thereafter. Section 23. Provides that the contract between the City and Johnson shall be held to have been fully made and agreed upon by the due enactment of this ordi- nance, and the terms of said contract shall be evidenced by the plans and specifica- tions and duplicate copies of this ordinance, duly approved by the Mayor and at- tested by the City Secretary, under the corporate seal of the City and the signature of the said Johnson. Section 24. Provides that all ordinances in conflict are repealed. APPROVED J. Bouldin Rector City Attorney PASSED: Sept. 7, 1911 APPROVED: ATTEST : Sept. 11, 1911 Jno. 0. Johnson A. P. Wooldridge City Clerk Mayor William D. Johnson gives Frank S. Taylor authority to sign contract, specifications, &c. June 17, 1911 Contract with Wm. D. Johnson dated Sept. 22, 1911 Voted by people Aug. 30, 1911. Contract published in Austin Daily Tribune Sat. and Sun., July 29 and 30, 1911 LETTEB FILED WITH CITY Austin, Texas, July 29, 1911 Hon. A. P. Wooldridge, Mayor of Austin, Texas. Dear Sir: I have read over the proposed ordinance * * * and I agree to the terms and obligations contained therein. I have today deposited with you as Mayor a full set of plans and specifications referring to said proposed work and the sum of $25,000, said plans and specifications and the said sum of money to be held by you upon the conditions contained in said proposed ordinance. Very truly yours, (Signed) Wm. D. Johnson. THE CONTRACT SPECIFICATIONS The specifications accompanying the above ordinance and made a part of the contract are exceedingly general in character and intended to be supplemented by detailed specifications to be afterwards furnished. A few of the important features of these specifications are abstracted as follows, italics are used to call attention to 62 Report on the Dam at Austin, Texas. important passages and the paragraph numbers are used for convenience in refer- ence and are not a part of the original : ABSTRACT OF CONTRACT SPECIFICATIONS 1. These specifications are intended to include the work, material, machinery, etc., necessary to the erection and completion of a dam across the Colorado River at Austin, Texas, at or near the location of the dam formerly erected across said river by the City of Austin ; the construction and equipment of a power plant at said dam ; the construction of a ten million gallon reservoir; the furnishing and setting of two electric motor driven centrifugal pumps in the City 's pumping station ; the construc- tion of a transmission line from said power plant at the dam to the City's steam power plant, and all connections and appurtenances pertaining to these several items ; all to be done for the City of Austin, Texas, by Wm. D. Johnson and his assigns, in a thorough and workmanlike manner, and in accordance with the general specifications hereinafter set forth. 2. It is specified and understood that these plans and specifications are meant to embrace every essential element necessary to the building, furnishing and completing of the dam, core wall, headgate masonry, headgates, power house, flumes, draft tubes, transmission line, two electric motor driven centrifugal pumps, reservoir, and all work embraced in these several items, and any essential element not mentioned here- in shall be considered as much a part of these specifications as if specifically set forth herein. It is also understood that all the work and materials specified or im- plied herein, or intended to be covered by these specifications, shall be performed or furnished by Wm. D. Johnson and his assigns (hereinafter called the Contractor) unless otherwise stated herein. 3. These specifications and the accompanying designs and drawings are subject to any changes that may in the opinion of the Engineer-in-charge f be desirable; pro- vided such changes do not decrease the amount of equipment in the power house, the height or stability of the dam, the size of the reservoir, or in any way diminish the capacity or completeness of the installation, or in any way lower the standard of the grade of construction. 4. Dam. Specifies materials, tools, etc. 5. Excavation. All loose material lying above the rock bed of the stream shall be removed from the site of the dam by sluicing or otherwise, and sufficient excava- tion for each cross wall shall be made into the rock, to secure, in the judgment of the engineer, good foundation and prevention against slipping of the dam all decayed or otherwise unsuitable portions of rock being removed. 6. Trenches for cut-off walls, at least two feet and for core wall at least three feet in width, and extending downward at least two feet into the solid rock, shall be made across the stream on the up stream and down stream sides of the new portion of the dam, and along such portion of the old dam as borings shall indicate to be nec- essary and in accordance with plans. Abstract of Specifications. 63 7. Grouting. Liquid grout, composed of a mixture of cement, fine sand and water, in proportions determined by the engineer (but not with more than three parts of sand to one part of cement), shall be pumped into two-inch drill holes made in the rock every thirty feet or less, if necessary, along the upstream face of the en- tire dam, under a pneumatic pressure of not less than fifty pounds per square inch. The object of this is to cause the rock underlying the up stream face of the dam below bottom of cut-off wall to become saturated with the grout, if it be porous or "seamy" or otherwise pervious, in order to prevent waste of water by percolation through the strata below the cut-off walls of the dam. In case cavities are discovered by this drilling, or in case any other unusual arrangement of the strata is discovered, the arrangement of holes may be changed, and the rock under the up stream face of the dam may be filled and made impervious in any other practical manner. 8. Cut-off Walls. In the trenches for cut-off walls, excavated two feet wide and down to solid, impervious rock foundation, which borings have indicated to be at least six feet in thickness, etc., etc. (This is followed by a brief description of the width of the walls and the composition of the concrete of which they are to be con- structed and authorizes the filling of additional trench back of the walls, with clay puddle.) 9. Supporting Walls. Describes the walls supporting the deck, and describes the deck of the dam. 10. Old Portions of Dam. Portions of the original dam, as constructed in 1890 and 1893, will be retained and used as portions of the finished structure to be com- pleted under these plans and specifications. This old work shall be thoroughly in- spected, and wherever there are loose stones or imperfect joints in the masonry, the work shall be made good to the satisfaction of the engineer. Pointing of the joints shall be done where necessary. 11. Great care shall be taken to thoroughly bond the new work to the old struc- ture, drill holes being made into same in order that anchor bars may be continued into the new work, to thoroughly tie the structure together. The contractor assumes the responsibility for the perfect stability and effectiveness of the portions of the old dam as parts of the finished structure. 12. Gates and Appurtenances. Describes flood gates to raise water five feet above the crest of the old dam and permit the passage of floods of 200,000 cubic feet per second. 13. Sluice Gates. Describes sluice gates and discharge passages. 14. Core Watt. Describes wall 300 feet long to be built in front and east of head works. 15. Track Walk and Pipe Line. Describes track and walk on top of gate piers and 24" cast iron water pipe to be laid if City so elects. 16. Reservoir. Describes reinforced concrete reservoir of 10 million gallons 64 Report on the Dam at Austin, Texas. capacity, the excavation of which is not to exceed an average of 4 feet beyond which extra compensation will be required. 17. Timber. Describes timber used as a permanent part of structures. 18. Cement. Describes cement to be used. 19. Sand. Describes sand for concrete. 20. Stone or Gravel. Describes stone or gravel for use in concrete. 21. Structural Steel and Steel Reinforcement. Description. 22. Forms for Concrete. Description. 23. Proportion of Ingredients. Described. 24. Mixing. Described. 25. Placing of Concrete. Described. 26. Power House. Described. 27. Head Gates and Hoists. Described also forebay and racks. 28. Intakes. Described. 29. Draft Tubes. * * * The material of the intakes or draft tubes now forming a part of the old plant may be used, if suitable, but in any event the metal must be of reasonably uniform thickness and strength throughout. These draft tubes must be properly and adequately supported in a thoroughly workmanlike manner. 30. Tail Race. It is understood that the outlet for water from the turbines used in the old power house, is buried with earth at the present time a considerable num- ber of feet and that the contractor shall uncover these openings and excavate a trench through the earth embankment at an an angle of approximately sixty degrees to the north and south line of the power house, in a downstream direction from the portion of the old power house now standing, to the river at low water. In this trench is to be placed a tunnel, or channel, of reinforced concrete, of ample capacity to remove the tail water from the turbines, which will be installed by the contractor at the pres- ent time, and also from the 1000 HP additional turbines for which the contractor is to provide intake, when all of said turbines are operating at full gate. 31. If channel be used, the wall on the upstream side of the channel wall shall be so buttressed as to withstand any outside pressure that is likely to be brought to bear upon it, and it shall be of such a height that any flood water cannot wash earth or silt into the channel over the top of said wall, either at the time said channel is constructed, or at any subsequent time. 32. This tail race tunnel, or channel, shall rest upon a good foundation, and shall be anchored to rock at intervals of not more than twenty-five feet, and shall be of suf- ficient strength to withstand any pressure from within or without to which it is likely to be subjected. 33. Power House Equipment. Described. 34. Pumps. Described. 35. Transmission Line. Described. 36. Engineer. Wherever the word "Engineer" is used in these specifications, the engineer representing Win. D. Johnson, and his assigns, is meant. The City of Austin shall have the right, however, to appoint a supervising engineer on the work, Abstract of Specifications. 65 whose duty it shall be to see that the specifications and plans are observed and fol- lowed in every material particular; and whenever in the judgment of the City's said representative engineer, the contractor is doing work or furnishing material which is not in accordance with plans or specifications, or which is otherwise improper, it shall be his duty to call the attention of the contractor's engineer to the discrepancy, and if the two engineers should fail to agree, then the City's engineer shall report to the proper City official the difference of opinion, and the circumstances in full. Said City official, on receipt of the information as set forth, may then immediately proceed as provided under the Arbitration Clause, Section 21 of the ordinance concerning the rebuilding of the dam, dated September 11, 1911. 37. It is expressly understood that the above specifications and the plans accom- panying same, are intended to cover, in a general way only, the work, materials of construction and the equipment referred to, and it is hereby further required that the contractor shall furnish, in duplicate, detailed plans and specifications of all materials to be furnished, work to be done, and equipment to be installed, to the City of Austin, Texas, at as early a date as possible after the signing of the contract ; and in any event such detailed plans and specifications shall be furnished the City, concerning any and all work to be done or equipment to be installed, or material to be furnished, before said work begins, or equipment is placed, or material is furnished. 38. The City's engineer shall have access at all times to all plans and specifica- tions which the contractor may desire to use, and the opportunity to consider same before the work represented thereby begins. PLANS The plans which, together with the ordinance and specifications, constituted the contract between Wm. D. Johnson and the City of Austin, consisted of seven sheets as follows : 1. General Plan and Elevation of Proposed Dam, Power House and Connec- tions. 2. Section of proposed reinforced Concrete Dam with Elevation and Plan showing Proposed Arrangement of Walls, Piers, etc. Piers 18" thick 12' c to c Upstream deck (by scale) 21" thick at base, 12" thick at top of dam; downstream deck by scale 12" thick. Width of dam, 125' 9". 3. Section showing Old and New Portions of Dam. Gate Pier on Old Dam 10' c to c. 4. Section showing Sluice Gates on Reinforced section of Dam, each Sluice Gate 8' deep 3y 2 ' wide. Hydraulic Cylinders for operating Gates inside of Dam. 5. Plan showing Location of Sluice in Proposed Dam. Four double gates. 6. Plans of Automatic Crest Gates, Bearings and Pivot Castings. 7. Isometric Drawing of Crest Gates. The type of reinforced concrete dam which was shown in these plans was appar- ently based on Patent 1,010,612, granted to C. F. Doebler, Dec. 5, 1911. APPENDIX 3 WORK UNDER JOHNSON CONTRACT or 1911 INCLUDING CHANGES IN PLANS PROGRESS OF WORK AND DEVELOPMENT OF CONDITIONS The work under the Johnson franchise contract of 1911 was started on Septem- ber 22, 1911, and prosecuted by force account until June, 1912, when a contract was entered into with the William P. Carmichael Company of St. Louis. First Change in Plans. A new general plan, numbered "Gen. 8", apparently based on Patent 1,010,131, granted to W. S. Edge, Nov. 28, 1911, was substituted and approved by A. C. Scott, Consulting Engineer for the City, on March 15, 1912. This change was approved with the knowledge and consent of the City Council. This new plan shows a rearrangement of the interior walls of the dam which were oblique to the axis of the dam in the original plans, normal to the axis in the new plan. The spacing of the gate piers was also changed from 12 foot centers on the new por- tion of the dam and 10 foot centers on the old portion of the dam, to 20 foot centers on the entire dam. Mr. Wm. D. Johnson assigned his rights and franchise (in April, 1912) to The City Water Power Company (a Connecticut corporation) organized to carry out the proposed work. Mr. Lamar Lyndon was employed as Consulting 'Engineer and Mr. Frank S. Taylor as Resident Engineer, and the work was carried out under their direction. Dr. A. C. Scott of Dallas, was appointed Consulting Engineer for the City, and about October of 1912, Mr. S. S. Posey was appointed Inspector for the City. Approval of Detailed Plans Including Certain Changes. In May, 1912, a set of nine detailed plans (numbered C-9 to C-17 inclusive) were submitted by Mr. Taylor to Dr. Scott, and after examination were approved by him in a letter dated May 20, 1912, to the Wm. P. Carmichael Construction Company. The original plans filed with the ordinance and specifications, as before noted, were very general in character and the adequacy of the structure outlined therein could hardly have been deter- mined from the data given therein without additional assumptions. Apparently no attempt was made on the part of the City to determine the safety or adequacy of the structure proposed, but full reliance was placed on the guarantee (see Sees. 10 and 13 of franchise ordinance). The detailed plans, C-9 to C-17 inclusive, were in sufficient detail to permit of analysis. The new plans were not compared by Dr. Scott with the original plans for the reason above stated. (See letter from Dr. Scott to E. C. Bartholomew, dated April 6, 1916, on file with City) and Dr. Scott did not notify the City of the changes in the detailed plans from the original plans. Progress and Character of Work. 67 These plans were furnished in accordance with paragraph 37 of the foregoing abstract of specifications. Under paragraph 38 of the abstract (page 25 of the orig- inal), the Company was obligated to furnish such plans for the consideration of the City's Engineer before beginning work, but no provision of the contract required the approval of the City Council, although if changes were involved outside of the limits prescribed in paragraph 3 of this abstract (page 2, original), they could not be legally made without such approval. The principal change made in those detailed plans was a reduction in the width of the dam from 125' 9" (shown on Drawing 2 of the original) to 93 feet (shown on Drawing C-17 of the new plans), and a rearrangement of the dam crest made neces- sary by the reduction in width. (See Fig. 5, page 17.) The City Council, not having its attention called to this change, remained un- aware of the same, and the Contractor on the basis of the approval of the plans by the City's Engineer, proceeded with the construction in accordance with those plans. Progress and Character of Work. Work was apparently begun at an early date on the power house. The remains of the original power station were extended north about 30 feet (see Fig. 29, page 69) and the plan of the equipment was changed from the original plan (see Fig. 14, page 43) to that shown by Fig. 28, page 68. The turbines, electrical machinery and centrifugal pumps for the City water works were received and set in the spring of 1913. The test of the pumps showed that they had only about two-thirds of the guaranteed capacity. After various tests, it was finally agreed (in 1915) that the Company should install an extra pump, thus giving the City three pumps, each of a capacity of four million gallons per day instead of the con- tract requirements (see Sec. 6 of the ordinance) of two pumps each of a capacity of six million gallons per day. The reservoir specified in the contract was completed in July, 1913, and, it is be- lieved, has been in continuous use to the present time. The work on the foundation of the dam was constructed at times when the con- ditions of the flow of the river would permit. Much difficulty and delay were occasioned by frequent floods in the Colorado River, and the cofferdams built for construction purposes were washed out some twelve or thirteen times while the work was in progress. In general, the work seems to have been well and properly done so far as the plans and specifications provided. In minor instances, objections were made by the Inspector, Mr. Posey, principally as to the depth to which the cut-off and core trenches were carried and as to the mix- ture used in the foundation concrete. These matters were adjusted from time to time by the Consulting Engineer, Dr. Scott. The concrete work seems sound and impermeable though somewhat rough. This roughness is of no serious importance except in the gate piers where the roughness of the work together with the swelling of the forms has apparently made it difficult to fit the crest gates so as to permit of the automatic action, for which they were designed, and at the same time to prevent serious leakage. 68 Report on the Dam at Austin, Texas. A general plan and elevation of the work as constructed are shown in Fig. 4, page 15. The foundation work was described in an article written by Mr. Frank S. Taylor for the Engineering Record of May 29, 1915, as follows : "The cutoff wall was carried down, in many instances, a considerable depth below the footings of the buttresses. This wall, on the upstream side of the dam, was poured in a trench which had previously been tested by numerous drill FIGUBE 28 Reconstructed Power House and Arrangement of Machinery as Installed under the Johnson Contract. (Bng. Rec. June 10, 1915.) holes, put down in the bottom of the trench. Where defects were found, they were remedied by grouting. The test holes were first spaced 12 feet apart in the bottom of the trench. Compressed air was turned into them, one by one, to dis- cover underground connections between adjacent holes. Wherever the com- pressed air would blow out of one or more of the other holes, it was considered that the entire seams or crevices between the two holes were reached by the drill holes then made. Grout would then be forced into one of the holes until it began to blow out of the others. It was then considered that the rock lying below the cutoff wall trench and between the holes had been made tight. Wherever no connection could be established between the holes 12 feet apart, intermediate holes were drilled, thus making the drill holes only 6 feet apart along certain Progress and Character of Work. 69[ 111 T 1 FIGURE 29 Power House during Reconstruction,Showing Addition to Remains of Old Station. FIGURE 30 Rock Trenches for Foundation Wall of New Dam. io'A Report on the Dam at Austin, Texas. FIGURE 31 Rock Trenches for Foundation Wall of New Dam. FIGURE 32 Concrete Foundation of Cross Walls FIGURE 33 Concrete Mat in Front of Sluiceways and Excavation for Concrete Mats for Sluice- ways. (Note Narrow Trenches.) Progress and Character of Work. 71 portions of the cutoff-wall trench. If, after this was done, no connection would be established between adjacent holes, additional holes intermediate to those 6 feet apart were drilled, bringing the distance to 3 feet. "In nearly every instance where these holes were made water flowed freely through them, sometimes spouting up 3 or 4 feet, thus proving conclusively con- nection between the holes made inside the cofferdam and the surrounding body of water. As grout would be forced into the holes, the velocity of water flowing out of them would gradually diminish, until it would entirely stop. In many cases, where grout was forced into a hole, the flow of water through other holes, some- times as far distant as GO feet, would be stopped and the grout would finally show, rising out of adjacent holes, proving that the underground seams between these two holes had been thoroughly filled with grout. In placing the grout the pres- sure on the liquid mixture was gradually increased from a few pounds to a max- imum of 80 pounds. ' ' As stated by Mr. Taylor, the cutoff walls and all of the foundation walls of the new dam seem to have been constructed in narrow trenches through rock which was found unfit for foundation purposes. (See Figs. 29, 30, 31, 32 and 33, pages 69 and 70.) In consequence of this method, it is quite apparent that the Engineers or Contractors on the work never had a comprehensive view of the foundation rock as a whole but examined it only along the narrow lines' of these excavations. The foundation work as above described temporarily fulfilled its purposes, and the Engineers of the City, Messrs. Scott and Posey, in their report to Superintendent E. C. Bartholomew, stated : "The Sluice gates were closed on December 12, 1914, and on the same date, work on the last cofferdam (below the dam) was started and rushed forward day and night to completion. This cofferdam, when completed, inclosed some ten or twelve acres of the river bed, and after being pumped out for service, an in- spection of the foundation walls and general condition of the partially completed structure was readily made. Such inspection disclosed a significant fact, viz: that while the head of water on the structure at the time was about fifty feet, the leakage through the same was entirely insignificant in quantity; which showed that the cut-off wall, foundation structure and upstream deck had been made impervious as required. Further evidence that satisfactory construction work had been done, was shown by the fact that only one eight-inch pump was re- quired to keep the water out of the large area inclosed by the cofferdam, while the downstream deck construction was in progress; and practically all of the water which was thus pumped came in from the downstream side of the basin through the sand bank constituting that portion of the cofferdam." On May 20, 1914, part of the retaining wall along the river between the power house and the dam, which had been constructed under the franchise, fell out into the river and was reconstructed, apparently on original plans. 72 Report on the Dam at Austin, Texas. On February 16, 1915, the water above the dam first reached the 60-foot level (the height of the original dam) since the failure of the original dam in 1900. The roof of the conduits leading through the dam from the sluice gates were destroyed by the pressure of the discharging water, apparently some time early in 1915. In March 1915 the turbines were tested and are reported to have given results better than the guarantees, although I have not been able to secure copies of the test. Early in April, 1915, the work being regarded as nearly complete, the City ad- vanced the Carmichael Company the sum of $21,000, which had been assigned to the Contractor by the City Water Power Company from the first payment due on accep- tance of the work. This was done by the City in order to secure the prompt comple- tion of the work. In the flood of April, 1915, four of the large crest gates went out but were re- placed immediately thereafter. A considerable amount of drift was caught and held by the gates and piers. The gates were found to leak badly, and a device for stanch- ing was applied which prevented their free action and later is believed to have been one of the causes of their destruction when the gates were suddenly opened by the excessive rise in the river. Previous to the destruction of the old dam in 1900, much rock was torn out by the floods from the river bed immediately in front of the dam and thrown up in a pile, the face of which averaged about 90 feet from the toe of the dam. (See Pig. 23, page 52.) When the old dam was destroyed, this pile of rock was augmented by rock from the old dam, although much of the rock previously deposited and much of the material from the old dam were carried farther down the stream. In the construc- tion of the new tailrace, a somewhat shallow channel was cut through the bar below the rock pile, but no wall was constructed as provided in the contract to protect the raceway from filling. (Sec. 31, Abstract of Specifications, page 64.) In the flood of April, 1915, this raceway was partially filled by debris from this pile of rocks. On April 20, 1915, the brick retaining wall between the power house and dam again fell out carrying with it a portion of the wall of the power house. About this time a leak appeared below the cutoff wall in panel number six. These various mishaps apparently created a suspicion on the part of the City officials that the work as constructed under the plans was not entirely in accordance with the spirit of the contract, and the City refused to accept the work until it was entirely completed in an acceptable manner. The City Water Company had originally issued $750,000 in bonds, but had taken down and sold bonds of a par value of $412,500 on which they realized 75 per cent, or $309,375, of which amount apparently $261,640.07 was paid to the Contractors, and the balance went to pay various other expenses. The Contractors, W. P. Carmichael & Company, had already expended a considerable amount in excess of their guaran- teed maximum contract price and were apparently unable or unwilling to furnish Progress and Character of Work. 73 additional funds for this work until they were assured of its final acceptance. It was to complete the work that the City advanced the sum of $21,000 before mentioned. Under these conditions a committee of the bond holders had been organized, and, with the hope of completing the work so th at it would be accepted and additional bonds could be taken down and sold to meet the indebtedness of the City Water Works Company, advanced the Contractors the sum of $11,242.62. About this time (May, 1915), the J. G. White Engineering Company of New York was appointed engineer for the work. The retaining wall which had twice failed, was rebuilt on apparently substantial lines, and various other work toward complet- ing the plant was carried out. The extra pump before mentioned was purchased and installed. The replacement of the roof of the discharge conduits, which had failed, was started, but the available funds were exhausted before this work could be com- pleted. In September, 1915, a still greater flood occurred in the Colorado River. Twenty of the large crest gates went out (see Fig. 8, page 25) together with most of the small ones. The tailrace was again partially filled (see Fig. 9, page 25), and the turbine draft tubes blocked (see Figs. 8 and 9, page 25), and the work on the pro- ject practically ceased. About this time the City Officials became aware that the dam had been reduced in width. The various difficulties with the crest gates convinced them that a ma- terial change in the design of the crest of the dam would be essential. The leak under the dam was also an unknown factor which involved much uncertainty. In order to determine the changes that had been made from the original plans, Mr. S. S. Posey, Inspecting Engineer, who had been on the work practically from the beginning, was requested to submit a report on the subject. His report is as fol- lows: Austin, Texas, May 20, 1916. Mr. E. C. Bartholomew, Supt. Water and Light Dept. Dear Sir: . At your request, I have gone over the plans and specifications for the re- building of the Austin Dam and made a list of the changes which the engineers have made in building the structure. I may have omitted a few minor changes but the more important ones, whether favorable or unfavorable, have been noted. Trusting that the attached list will meet your requirements, I am Yours very truly, (Signed) S. S. Posey, Inspecting Engineer. 74 Report on the Dam at Austin, Texas. CHANGES MADE IN REBUILDING THE AUSTIN DAM 1. The Eansome type was proposed, the Edge type was used. This change was taken up with the City Council and considered principally in a re-arrange- ment of the supporting walls. On the original drawings some of the walls were not at right angles to the decks or to the axis of the dam. As built, they are at right angles to both and are spaced 20 ft. apart instead of 24 ft. 2. The base of the dam was narrowed up from 125' 9" to 93' 0", modifying the crest so that it overhangs the upstream deck. This did away with one of the longitudinal walls bracing the upstream deck. 3. Large crest gates increased in length from about ten to eighteen feet. 4. Small crest gates increased in length from about eight to eighteen feet. 5. Foot bridge on top of dam changed from steel I-beam and wood construc- tion to reinforced concrete and wood, to make it strong enough to support the derrick car which they expected to use for handling the crest gates and drift. 6. The specifications call for a reinforced concrete floor supported by I- beams in the Power House; built partly on earth fill and reinforced concrete slab supported by reinforced concrete girders. 7. Large crest gates made in two weakly connected halves instead of one well-braced whole, as shown on sheet No. 6 of the original drawings. 8. Middle bascule and intermediate pier introduced in center of openings for large crest gates, adding an additional obstruction to drift. 9. Bascule castings changed from rack type to plain. 10. Location of sluiceways changed from the original plan, three being lo- cated in the river channel instead of one. 11. Thickness of supporting walls changed from one foot at base to two feet six inches at the same point, diminishing to one foot at the top, thus increasing the bearing on the foundation. 12. Thickness of upstream deck slab increased at bottom from two feet to two feet six inches and at the top from one foot to one foot eight inches. The steel in the same decks, as well as that in the downstream deck, has been re-ar- ranged for the better, though the amount used remains practically the same. 13. Cut-off walls on both upstream and downstream sides of the old dam omitted, except for about one hundred feet immediately west of the head gate masonry. This was left to the discretion of the City Water Power Company's Engineer unless the City wished to invoke the arbitration clause. In the in- stance mentioned, the upstream cut-off wall was not, in my opinion, carried two feet into good rock (though I was over-ruled by Dr. Scott, who passed on it as satisfactory, because of its impermeability, as shown by holes drilled in the trench and attempts made to force grout under pressure into it.) Under the toe of this same portion of the old dam, and under the ragged break at its west end, a cut-off wall eighteen inches thick (instead of two feet as specified) and six feet Changes Made in Rebuilding Dam. 75 in height, was built to protect the toe from scour, but the material upon which it rests is soft enough to be easily scratched by the finger nail, which was not, of course, according to specifications. 18. The specifications require that the proportions of material in the con- crete shall be : one part cement, two parts clean sand, and four parts, crushed stone or screened gravel. The engineer for the City Water Power Company al- lowed the contractors to use pit-run gravel, i. e., sand and gravel mixed as it comes from the river beach, getting the proper proportions by adding stone or sand as determined by taking voids by means of water. Also keeping the voids in the aggregate within certain limits by the same means. An excess of cement was required and used because of this change. 19. The fourth penstock, as required by the specifications, was omitted by permission of the City Council. First class material was specified for these tubes. Old ones, some of which were badly pitted by rust, were used. Outside of the Power House these penstocks were well covered with reinforced concrete ; inside of the building on both the inside and outside of the pipes and outside of the building on the insides of the pipes, "smooth-on" was used on the joints and defects, besides being coated with a wash made of retempered cement. 20. The core wall was not carried as deep, as high, nor as far into the bank as specified, but this was passed upon by the City's representative as being all right because of the impervious character of the "adobe" on which it rests and because the head gate masonry was considered sufficiently tight without the pro- tecting wall. The water does, however, percolate through it in places in small quantities. 21. The tail race as described in the specifications has not been built up to the present time, this being according to a verbal understanding among those concerned, if certain conditions were met. 22. The pointing of the joints of the masonry of the old dam was not done because considered unnecessary by the Engineer for the City Water Power Company. The seepage at the east end of the old part demonstrates the neces- sity for pointing or grouting. (Signed) S. S. Posey, Inspecting Engineer. The City was unprepared to advance more money until the work was placed in acceptable shape, and was unwilling to specify just what it would require before the work would be accepted. The bond holders on their part were naturally unwilling to add more funds unless they could be assured that such additions would complete the work to the entire satisfaction of the City Council, and the Contractors were obliged to make assignments. While the conditions have been hastily examined by various engineers and brief reports have been made in the interest of the bond hold- ers and various other interested parties, nothing has been done toward completing the plant for about two years. APPENDIX 4 CONDITIONS AND FACTS ASCERTAINED DURING EXAMINATION BY DANIEL W. MEAD AUG- UST, 1917 Early in July, 1917, the writer was engaged by the City of Austin to investigate the conditions and to report on the situation as it now obtains at the Austin Dam. Before commenting on the present plant and outlining the betterments which should be made in order to place the same in safe condition for proper operation and main- tenance, it is necessary to review the physical conditions which exist at the site of the works. It is obvious that the examination of a completed structure with the water stand- ing 10 to 20 feet above the foundation is attended with much difficulty, and that to draw conclusions from any examination which can be made under such conditions, without incurring a prohibitive expense, makes it necessary to depend largely on the statements of those who have been in personal touch with the work during its con- struction, at the same time checking up such statements by comparison with those made by different witnesses, and by the facts that can be definitely determined. Pre- liminary to his examination the writer read all of the articles which he could secure that have been written on the Austin dam, a list of which is given in a later appendix. On reaching Austin, the writer visited the City office and discussed the matter at some length with Mayor Wooldridge, Superintendent Bartholomew, and the mem- bers of the City Council. He also had access to the various letters, papers and plans which are in possession of the City. He also discussed the matter in detail with Mr. Guy A. Collett, Receiver for the City Water Power Company, who placed all plans and data which he possessed at the disposal of the writer. The writer also secured considerable information from Mr. H. L. Cobb who was Assistant Engineer in charge of the grouting and other construction work. Mr. Cobb furnished a large album of photographs showing various views taken during the construction and at various periods in the work. Other views, especially of the older work, were ob- tained from the engineering papers, the local photographers and others. A number of these views are reproduced in this Report and show clearly the conditions which existed at various periods, which can be clearly understood now only by the informa- tion these views contain. Mr. S. S. Posey, who had been Inspecting Engineer for the City during the con- struction work, spent most of his time with the writer during his stay in Austin. Mr. Posey 's knowledge of the conditions greatly facilitated the writer's examination. Mr. Frank S. Taylor, who was Resident Engineer during the construction, placed his information and data at the writer's disposal, and furnished much information of Foundation Walls. 77 o X fl .2 .2 3 +* tl O fl -4-J P 0) 0) ,M bfi CQ = CO a, 02 fl fe 5 80 Report on the Dam at Austin, Texas. the conditions which developed during construction, and of the foundation depths and conditions. This information was quite indispensable to the conclusions of the writer. Mr. Frank S. Taylor was Resident Engineer of the work done under the fran- chise given Mr. William D. Johnson. He was in immediate charge of the construe- FIGUBE 40 Sketch showing Depth, Thickness and General Arrangement of the Foundation Walls. tion from the beginning of the work until it was practically discontinued early in 1915. Mr. Taylor furnished the writer with a series of seven sketches, copies of which are shown in Figs. 34 to 40 inclusive, which sketches show in general the depth to which the foundation walls were taken, and the thickness and general ar- rangement of such walls. Mr. Taylor also furnished a detailed memorandum con- cerning the holes drilled for the purpose of grouting the foundation, and the results of the grouting, which throws much light on the conditions of the bottom as deter- mined during construction. He also furnished a blueprint plan of the foundations, showing the location of all grout holes, which (with some additions) is reproduced in four sections, shown in Figs. 41 to 44, pages 82 to 85 inclusive. Foundation Conditions. 81 MEMORANDA CONCERNING THE FOUNDATION CONDITIONS OF THE AUSTIN DAM FROM SKETCHES AND DATA FURNISHED BY MR. FRANK S. TAYLOR Concerning this work, Mr. Taylor says: * * The attached logs of drill holes and subsequent grouting operations in the Austin Dam are approximately correct. The lines showing the probable direc- tion of permeable parts of the foundation are indicated as follows: "All foundations east of No. 44, impermeable. "Possible permeable lines thru dam foundation as indicated by numbered holes on the 'Grout-hole Chart': 44 to 68, 59 to 98, 78 to 117, 81 to 108, 136 to 153, 141 to 165, 152 to 166, 159 to 180, 171 to 182, 210 to 208, 223-228 to 236, 242 to 247, 252 to 261, 255 to 263, 271 to S. W., 277 to S. W. (These 'possible per- meable lines' have been indicated by lines on the diagram, shown on pages 82 to 85 inclusive. D.W.M.) ' ' Nearly every hole in the cut-off-wall foundation which proved to be in per- meable strata, was found to be in permeable strips, bounded by more or less defi- nite lines running parallel to a South West direction thru it. * ' The lake was filled while operations were still in progress on the spillway. There was then a cofferdam across the river down stream ; a 4,000,000 gallon per day pump working less than half of the time kept out all water from the coffer- dam until the water ran over the dam at elevation 151. At this time, however, the flow of the river at the rapids, about 1000 feet below the dam, indicated that about three times as much water was flowing there as was pumped out of the coffer. ' ' This last statement would seem to indicate that while there was little seepage under the dam, and rising inside the cofferdam, that about twice this amount was rising as springs in the river below the cofferdam and above the rapids referred to. In the following pages, abstracts have been made of the records of the grout holes through which a considerable amount of grout was forced into the foundation. The grouting work was done by means of a grouting cylinder under pneumatic pressure. The cylinder was 18" in diameter and 42" in height, connected with an Ingersoll-Band air compressor with an intervening air receiver of about 100 cubic feet capacity (see Fig. 45, page 99.) Mr. Taylor says: "General Scheme of Tests. It was decided to make the holes first grouted 24 feet apart. It was assumed, and afterwards did develop, that the grout would, in many cases, go from one hole to another through crevices and between strata of limestone. After the adjacent 24 feet holes were grouted, another hole was drilled midway between these two, making the holes 12 feet apart. The log of this intermediate hole was carefully watched, as, from the indications found in the drilling, we could determine where grout had sealed all crevices be- tween the two holes 24 feet apart. If, as in many cases, we found that there were some crevices which were not filled by either one of the first two holes, the 82 Report on the Dam at Austin, Texas. =4 o Record of Drilling and Grouting. 83 84 Report on the Dam at Austin, Texas. b Record of Drilling and Grouting. 85 - O 86 Report on the Dam at Austin, Texas. grouting machine was placed on the intermediate holes, and, in fact, our prac- tice was to place the grouting machine on this intermediate hole even if we found no indication of permeability. In some locations it was found that even this short space was not sufficiently close together to satisfy us, and, in such cases, other holes were bored between the 12 foot spacings and the operation just de- scribed repeated, reducing the distance to 6 feet apart. In a few cases we found that holes between the 6 foot borings were necessary to give us a satisfactory evidence of impermeable foundation. ''Auxiliary Holes Under and Between Diaphragm Walls. A great many holes were bored, as shown, only 5 feet deep, but these holes were bored on the downstream side of the cutoff wall, which has been made impermeable, as al- ready described, and the purpose of the 5 foot holes was to determine only the solidity of the foundation for bearing our walls. In a great many cases, water was found in these shorter holes, and wherever the findings of the drill indicated a cavity or seam, that hole was grouted in exactly the same manner as if it were in the cutoff wall. It is probable, however, that all of the water that developed in the shorter holes came from downstream pressures, the mouth of all of these holes being from 8 to 15 feet below the level of the water on the downstream side of the lower cofferdam. "On the Downstream Side of the Old Dam. A number of holes were bored on this part of the structure, as shown on the chart, and the grouting machine was placed on same for the purpose of testing the permeability of the strata un- der the toe of the dam, but little grout was forced into these holes, the testing being done with water only. In two or three holes the test proved that there was a permeable strata under the toe of the western end of the old dam, but our op- erations afterwards, on the upstream side of this same section, comprehended the entire length of the dam and to a depth of 12 feet, so that there is every rea- sonable indication that the grouting hereinafter described filled cavities that were discovered by the tests on the downstream side of the old dam." In the abstract of the record of the grout holes, shown on plans Figs. 41 to 44 (see pages 82 and 85) are given: 1st. The number of hole. 2d. El., the elevation referred to a horizontal plane 160 feet below the crest of the dam, or approximately 100 feet below the average low water level. 3d. "D", the depth of the drill hole below the elevation given; and 4th The amount of grout forced into the hole, indicated in cubic feet. The grout was a mixture of one part of cement and two parts of fine screened sand, with water to make a grout of creamy consistency (each charge from the cyl- inder being equal to about 2 cubic feet of grout). The word "attempt" is used to ex- press each separate operation of the grouting machine. The records of all holes that took no grout are omitted from this abstract : Record of Drilling and Grouting. 87 ABSTRACT OF RECORD OF DRILLING HOLES AND GROUTING (NOTE The numbers serve to locate the position of each hole on the Grouting Charts) 40. Elevation 86; depth 12 ft.; no cavities. First attempt blew grout out in trench at lower level about Station 22. Later, second attempt showed oozing of grout in side of trench above top of hole, stopped during discharge. Third at- tempt, refusal. 44. Elevation 82; depth 11 ft. in cracked rock. Two inch cavity at 4th foot; 37 full discharges of grout forced into pipe. Crack extended across cutoff wall from northeast to southwest and was from 14" to 6" wide. The 37th charge filled all crevices to refusal. 54. Elevation 81 y>; 9 ft. hole; 2 ft. in soft rock; cavity for iy 2 feet then 4y 2 feet of good rock ; then about one foot of soft rock ; balance hard rock. First at- tempt discharged grout through crevices. Several charges attempted with thicker grout evidently discharging through crevices. Later, y 2 charge oozed through crev- ices and cracks stopped. 58. Elevation 81 feet; 10y 2 ft. hole; 5" cavity in 5th foot; soft rock 9th foot; balance solid. First attempt forced grout through crevices at pier footings between diaphragm walls 5 and 6, about 70 ft. from No. 58. Twenty-two full charges were put in before refusal. 59. Elevation 81 ft.; depth 10 ft. Water appeared at 4th foot; soft rock at 6th and 7th foot; balance good rock. First attempt forced water and grout to surface in the vicinity of hole. Nine charges put in before refusal. 61. Elevation 81 ft.; depth 8 ft.; soft rock in 3d, 4th and 7th foot; balance good rock and grout. Four full charges. 64. Elevation 81 feet; depth 9 feet. One foot of soft rock. One foot of soft rock in 7th foot. Six full charges ; 7th attempt discharged grout in vicinity of No. 72 and filled holes Nos. 65 and 66. Later, after grouting Nos. 70, 71 and 72, made 8th attempt nearly full discharge. Total about 7 charges. 68. Elevation 81; depth 11 ft.; Sy 2 ft. good rock and grout; 6" soft rock; balance good. Continuous grouting for about 25 hours. Forty-eighth charge showed indica- tions of grout all along line of crevice encountered at No. 44, also at No. 65 and No. 66. Fifty-six full charges before refusal. NOTE. Operations from No. 44 to No. 69 were evidently contiguous to the crack described in No. 44, which follows the general direction of the larger fault lines of the Balcones fault zone. The fault lines found in the limestone across the river at the dam are nearly vertical, and, with the exception of this crevice and one described as crossing the cut-off wall at about Station 8 + 25', the lines are cracks, which evi- dently do not change the solidity of the stone, nor cause a break in the lines of stra- tification. 88 Report on the Dam at Austin, Texas. 72. Elevation 81 ft. ; depth Sy 2 ft. in good rock and grout except one crack in 4th foot. First and 2d charge forced grout through crevice near by. Later 20 charges put in; 23d attempt, refusal. 76. Elevation 81 ; depth 5 ft., when drill stopped in crack. Good rock. Grout came into this hole from No. 78. Hole piped above footing course of wall No. 6 later. First attempt forced grout around footing near by; second attempt took full charge; third attempt, refusal. 78. Elevation 81 ; depth 10 ft. Soft spot in 6th and 8th foot. Third attempt forced water from Nos. 76 and 77. Thirteenth attempt forced air through crevices at about No. 73 ; with 41 full charges, all crevices filled to refusal. 90. Elevation 82 ; depth 10 ft. Cavities and soft rock in 7th, 8th, 9th and 10th foot; balance good. First attempt blew air and water in No. 89; second attempt showed at No. 108 ; 6th attempt stopped indications at 108 ; water again running from 108 and oozing nearby after 7th attempt. Grout still going in with 16th charge; 17th charge oozed nearby and in excavations for Nos. 7 and 8 diaphragm walls ; 28th charge forced water and red mud 25 feet south of hole ; 35th attempt forced grout through crevices ; 36th attempt still forcing air out of trenches of diaphragm walls Nos. 6 and 7. Same conditions with 47th attempt; 54th attempt showed clean grout forced from every place where air had been noted ; 63 full charges put in with prob- able loss of about 10 per cent. 92. Elevation 81 ; depth 10 ft. ; solid rock and grout except 7th foot which was soft and cavity. Sixth charge showed water running freely through crack nearby; llth attempt spouted water and grout in foundation of diaphragm wall No. 10 and forced air through crevices in No. 9 diaphragm wall; 40th attempt, refusal; 48 charges put in. 95. Elevation 81 ; depth 10 ft. ; 8th and 9th foot soft ; balance good rock. First attempt blew grout and water out of No. 96 ; 5y 2 charges put in. 98. Elevation 80 ft. ; depth 10 ft. ; 5th, 6th and 7th foot soft ; balance good rock. First five charges forced air and water through No. 101 ; 8th attempt, refusal ; total 8 charges. 108. Elevation 82^ feet; 10 ft. hole. Eock seamy but hard; 3 charges put in. 117. Elevation 83 ; 10 ft. hole ; solid rock except crack in 2d foot and soft rock in 9th and 10th foot ; 7 full charges put in with nearly full charge and refusal at 8th attempt. 136. Elevation 8y 2 ft. ; 11 ft. hole in solid rock except soft spot in 7th foot. First attempt forced water through crevices; 4 charges before refusal. 141. Elevation 84y 2 ft.; depth lift. First 8 feet solid, then iy 2 feet soft; bal- ance good. Second, 3d and 4th charges blew yellow mud from 145a, and water and grout continued to flow from 145a with 7th and 8th attempts ; 10th to 18th attempts forced grout and water through 148. Nineteenth and 20th attempt forced grout from No. 144; pipe at 144 then plugged. Thirty-first attempt, refusal. About 27 full charges. Record of Drilling and Grouting. 89 147. Elevation 84; 11 ft. hole. Soft spot in 2d, 5th and 7th foot; balance good rock. At 5th foot water flowed from hole ; nearby water was flowing from crevice in rock in which a 3" pipe had been cemented, confining the flow from crevice to said pipe. First 11 charges each forced water out of 3" pipe ; 12th charge forced grout from 3" pipe, and the latter was plugged. The 23d charge, plug removed from 3" pipe. Grout going in slowly with the 58th charge. Sixty-third attempt refusal. Machine moved to 3" pipe with refusal at first attempt. Total, 62 charges. 153. Elevation 83. This hole was one of the core bore holes made previously by the City of Austin, being No. 19 on chart herewith (see page 54). Depth about 20 ft. This hole was in foundation of diaphragm wall No. 16, and the water was piped up and the wall concreted. Water rose in pipe to water level (outside coffer). First attempt, full charge ; afterwards charges were put in rapidly without appreci- able resistance until pipe was full; 157 charges. 155. Elevation 85; 11 foot hole; in good solid rock except soft in 8th and 9th foot. First attempt forced grout from around footing and in pump sump at north end of diaphragm wall No. 17. Thirteenth attempt, all blew out at sump. Stopped at this point because all grout was lost. Probably about net 12 charges. 160. Elevation 85 feet. Cemented pipe in crevice at this location. Put in 41 charges when cofferdam failed and water covered the hole. After break in coffer, refusal at 43d attempt ; total 43 charges. 161. Elevation 85; 5 ft. hole in good rock except cavity and soft spot in 4th foot. First 5 attempts forced grout from crevice in all directions within radius of 15 feet. Forced water and mud from No. 167 and grout at 20th charge. After plugging No. 167, refusal at 77th charge; total about 75 charges. 166. Elevation 86 ; depth 5y 2 feet. Water bearing sand in 4th foot ; balance solid ; 4th attempt forced air and water to crevice in lower end of trench of No. 18 diaph- ragm wall. Second and 3d attempts filled all crevices and forced grout from No. 180; total, 11 charges before refusal. 171. Elevation 87; depth Iiy 2 feet. Four feet hard rock; iy 2 ft. soft; then 2y 2 ft. solid followed by iy 2 feet soft rock; balance good rock. First 7 attempts dis- charged water and mud from No. 162 and in various nearby crevices. Hole cleaned and left ; later, successive attempts after the 8th showed same indications ; 18th at- tempt forced water from 173. Indications of permeability decreased and practically stopped at about 40th charge. Total 43 charges. 177. Elevation 87; depth 43,4 ft. Solid rock with seam at 3y 2 ft. depth. Grout- ing in this hole showed increase of water in Nos. 179, 178, 184, 183, 182 and 181. This hole took 19 full charges before refusal. 179. Elevation 86^; depth 5 ft.; solid rock but water flowed from the hole. Three holes were drilled in this vicinity, water flowing from each one. The flow was greater after subsequent blasting of trench foundations; evidently the water in all of those holes came from the same seam. First charge showed grout coming up in No. 182; total of 22 full charges. 90 Report on the Dam at Austin, Texas. 182. Elevation 87y 2 . This was one of the holes mentioned in No. 179; 10 full charges before refusal. 187. Elevation 88. This hole was piped up through footing of diaphragm wall No. 20. Took 12 charges, after which grout began to flow from seams near footing. Seams were calked and later 5 more charges were forced into the hole. This caused grout to show in No. 186. Total of 17 charges before refusal. 210. Elevation S9y 2 . Near this hole, water coming from crevices in foundation nearby, also water coming into cofferdam through large hole about elevation 90. First charge at low pressure and charges continued. Grout color showing from various crevices even to a distance of 120 feet to the big pump sump hole. Moved grouting machine at about the 90th charge to No. 214, then back to No. 210 ; then moved to No. 192 which took no grout ; then back to No. 210 ; with total of 115 charges, springs stopped and the big hole was bailed out by hand. 212. Elevation S9y 2 ; depth 10 ft. ; good rock. Put in 11 charges when it was evident that grout was being forced out of nearby crevices as fast as put in. Three days afterwards, another attempt was made without success. Second attempt, re- fusal. 214. Elevation 91 ; depth 11 ft. Good rock except soft in 7th foot. Five charges put in, blowing out at 213 and near 210. After grouting No. 210 several days after, machine was again put on No. 214 with refusal at 4 different attempts. 222. Elevation 92; depth Iiy 2 feet; 8ft. solid rock, then 1 foot soft; then 2y 2 feet solid rock. Took 10 full charges before refusal. 225. Elevation 92 ; depth ll 1 /^ feet. Solid rock except soft in 8th foot. Water flowing. Three full charges. 226 Elevation 92 ; depth 12 feet ; solid rock. Water seam about 10th foot. Hole took 47 full charges. 229. Elevation 92 y 2 . This was one of the bore holes made by the City some years ago. First charge forced grout into No. 228 which had not yet been grouted, and in No. 231, and showed air bubbles within a radius of 10 or 12 feet. First few charges stopped all leaks. Eleven full charges put in. 232. Elevation 92y 2 . No log of drilling. Took 17 full charges. 235. Elevation toe of old dam; about 9 foot hole; 5 feet in grout and 4 feet in limestone and mortar. Poured in water and it ran through the hole. Put on grout- ing machine and it took one full charge ; afterwards 10 charges ; later about y% charge; total 10y> charges. 236. Elevation toe of old dam. Depth about 4y> feet. Water ran freely through hole; took 12 full charges without showing any indications from outside or in water below the dam. Thirteenth charge blew out through the joints in the granite nearby. After cleaning the hole and plugging the joints, replaced machine and the hole took nearly one full charge before refusal. Total about 13 charges. Record of Drilling and Grouting. 91 242. Elevation 93y 2 ; 11% ft. depth. Solid rock except slight drop 19th foot. Water flowed freely from hole. First few charges blew out in No. 244 and evidently forced grout around No. 240, because water began to flow from that hole although it had previously been grouted. This flow finally stopped. The vicinity of this hole was covered with mud and the operations were conducted with care, observing all possible leaks of grout. After a few charges, all indications of bubbling in the water or color of grout ceased. Ninety-three full charges ; then refusal. .243. Elevation 93y 2 ; depth Iiy 2 ft. Solid rock except soft spot in 8th foot. Water flowed freely from hole and showed bubbles in crevices about 60 feet up- stream. Charges went in without indications of leak after the first 2 or 3 up to the 37th, when grout came through No. 245. Plugged this pipe and continued until 47 charges had been put in. 244. Elevation 94 ; depth 11 ft. Solid rock with soft spot in 8th foot. Twenty- four full charges were put into this hole under maximum pressure for each charge. 246. Elevation, toe of the dam; depth 11 ft. Total of two charges before re- fusal. 255. Elevation 95 ; depth 11% ft. Solid rock except soft in the 8th foot and last foot. Air and water forced in this hole proved it to have outlets. First few charges with no surface indications. This hole grouted to refusal with 60 full charges. 258. Elevation about 95; depth 11 ft. Two full charges and then grout blew through crevices around hole ; 4 additional charges were probably largely lost ; prob- ably about 3 full charges. 260. Elevation 95; depth 11 ft. Solid rock except soft places in 9th and 10th foot. Took 7 full charges with no indications of leaking nearby. 261. Elevation, toe of old dam. Depth 11 y 2 ft. in granite, limestone and mortar. Last foot soft material. Water ran freely through this hole and 93 charges were placed without evidence of loss. Grout was forced in with light pressure except last few charges. Final refusal at 80 pounds pressure. 263. Elevation below toe of dam. About 11 foot hole in granite, limestone, mor- tar and flint. First few charges showed leaks nearby which finally ceased. Took 43 full charges. 271. Elevation 95% feet. Depth about 18% ft.; 6% ft. solid rock; one foot water bearing, soft ; balance rather soft but solid. Water rose when drill reached about 8 feet. Fourteen charges put into this hole under maximum pressure of 70 pounds. 276. Elevation about 96 ; depth 11% ft. ; 7 ft. solid rock, then one foot cavity ; afterwards 3% feet of solid rock. This hole when tested, evidently had openings un- derneath the dam, shown by bubbles in water below toe of the old dam reported by laborers afterwards. This hole took a number of charges, probably 25, without max- imum pressure, after which charges were put in with gradually increasing pres- sure. Total of 57 charges put in with refusal. 92 Report on the Dam at Austin, Texas. 277. Elevation about 96 ; depth about 10 ft. ; 4 ft. solid rock and about y 2 ft. soft rock or clay ; then 5 ft. of limestone. Water leaked away rapidly. Grout forced at about y 2 maximum pressure up to 20th charge. Put in 27 charges, the last at about 60 pounds pressure. Breakdown in machine stopped operations and before resump- tion concrete had set in the cracks. Number 278 was then drilled which took about y 2 of a charge. NOTES BASED ON INFORMATION FURNISHED BY MR. S. S. POSEY (Mr. Posey was Inspecting Engineer for the City of Austin, beginning his work at the Dam some time after excavation had begun but before the first concrete was poured. He began his inspection about October 20, 1912.) The information furnished by Mr. Posey was of much value, and for the pur- pose of this Report has been abstracted as follows: The structure now constituting the Austin (Texas) Dam consists, in its western portion, of about 500 feet of the original structure, built in 1893, 560 feet of the new structure, built under the contract of 1911; and on the east of about 60 feet of the original 1893 structure, also the original head works and a core wall extending about 300 feet east from the east end of the spillway. The so-called core wall consisted of a narrow concrete wall, built in excavation, north of and adjacent to the original head work masonry and extending easterly therefrom. From the west end of the head work masonry the bottom of the cut-off wall dropped downward, holding a depth of approximately two feet below the rock bottom or about one foot below the cross walls of the dam. Cross Walls. The cross walls (i. e. the walls at right angles with the face of the dam) are numbered from the east, the one at the end of the new work being number 0. In general, the trenches for the cross walls of the dam, penetrated the surface rock approximately one foot. Walls 4, 5, 6, 7, 8, 9 and 10 were built in trenches ex- cavated to an extra depth, wall 8 being the deepest and extending down 22 feet below low water. Beyond wall 8 the condition of the rock of the bottom improved in qual- ity somewhat and the cross walls were carried to a less depth. At wall 18 and be- yond, the excavation for the cross walls was made with pot shots. The depth below low water to the rock surface being about 12 feet at wall 18 and sloping upward to a depth of 9 feet at wall 27. From wall 18 to wall 27 the cut-off wall was carried down below the surface of the rock about two feet. From wall 15 to wall 27 the gen- eral slope of the foundation rock is down stream and is about two feet in the width of the dam. The cut-off wall was carried westward to the end of the new work and no further and no cut-off wall was placed either at the heel or toe of the west portion of the old dam. A curtain wall about 18 inches in thickness and 6 or 7 feet in depth was carried from the head gate masonry westward along the toe of the east portion of the old Leakage. 93 dam underneath the new construction and underneath the broken end of the old dam until it encountered the cross wall of the new construction. Leakage. Near the east end of the west portion of the old dam for about 80 feet, the grout that was forced into the 11 ft. holes under 80 Ibs. pressure came out of the old dam masonry joints at the first, second, third and possibly the fourth joints above the foundation. On the toe of the west portion of the old dam a number of two inch holes were drilled through the masonry and to a depth of about 11 ft. Water came through the toe from some of these holes. Air forced into some of these holes at perhaps 60 to 70 Ibs. pressure appeared in the drill holes above the dam and in the cracks of the foundation rock. Water also rose and overflowed through a hole drilled into the face of the dam about 8 feet above the toe. With the lake full, water seeps around the west end of the old dam through the rock and appears as seepage on the face of the bluff to a point perhaps ten feet be- low the top of the dam and springs apparent along the bluff for a distance about 100 feet below the dam. Evidence of leakage into the natural rock on the east side of the river was found at the following points: 1st. Under the new forebay wall, in the dry wall of the old forebay and east of the northerly end of the boom. 2d. Under the masonry of the City wharf about 200 feet north of the dam. 3d. In Walsh's Slough near the northerly end of an old clay dam which was constructed by Mr. Walter Johnson to save water during the operation of the old plant. 4th. In the upper end of the Taylor bluff, perhaps a half mile north of the dam. It is Mr. Posey's belief, from the direction of the opening from hole number one, that the "corewall" was not carried deep enough to cut off the water from this source. However, an opening under the westerly penstock, now in place, was cut off by the "corewall." From the various openings above described and perhaps from many others not definitely located, a considerable amount of water seeped into the east bluff above the dam and appeared as springs and seep water at various points for nearly a half mile below the dam. Some of these points may be described as follows : 1st. A small pipe near the north end of the retaining wall. This flows very strong at full lake and is now dry with water at elevation 16. 2d. A small pipe under the north draft tube which flows full at full lake but is now stopped. 3d. A 2-inch pipe built into the wall facing the bluff and between the two south turbines which also flows full at full lake level. 4th. The head gate masonry also shows seep water to a considerable height above the ground. 94 Report on the Dam at Austin, Texas. 5th. There is also seepage through the face of the rock at the south end of the power house. 6th. In springs which show on the river face of the foundation wall near the south end of the power house, south of the present draft tubes. At full lake this spring required a 3-inch centrifugal pump to take care of it while building the concrete blocks at the ends of the draft tubes, and the water is still flowing with the lake level at elevation 16. 7th. Seepage through joints in the clay bank, beginning about 200 feet south of the dam, and extending 1000 feet or more in a southerly direction. 8th. Seepage also appears in the form of springs in three draws south of the dam, the strongest one being the one farthest south from the dam, which flows approximately 8 to 12 second feet. The next strongest one was about one- fourth mile northward toward the dam, which flows strong enough to rapidly erode the east bank. Between these two springs the water came out in the alluvial field about 30 feet above the river to a sufficient extent to destroy a crop of cantaloupes for a market grower. The south spring issued first from an opening in the rock 20 feet above the river, and later appeared at an elevation about 10 feet lower. None of this water appeared until about a month after the water in the lake rose to the higher levels. Leak Under the Dam. As previously noted the walls of panels 4 to 10 were carried to an extra depth on account of the poor condition of the foundation rock. After the construction and filling of the dam a leak appeared in the sixth panel of the new dam about 5 feet down stream from the cut off wall, and near the east side of the intermediate wall. As the flow from this was very large (perhaps 30 second feet), an attempt was made to close off this leak. The running water had thrown up a bank of sand, gravel and mud across the bay to near the surface of the water and a coffer dam was constructed by driving Wakefield sheet piling into this deposit from the east wall of the bay to the east side of the intermediate pier. A 4-inch centrifugal pump and motor were installed. The water did not rise after the construction of the cofferdam nor was the pump able to lower the water, although it was speeded up and was attached to a powerful motor. A diver who examined the opening found that it was of sufficient size so that he could stand in the opening and the surface was about level with his arm pits. From this position he said he could reach the cut-off- wall. He also stated that the water appeared to come from a downstream direction and impinge against the cut-off wall. An earth cofferdam was built immediately opposite the position of this leak on the upstream side of the cutoff walls and atove the dam. The water in this cofferdam could easily be lowered and there was evidently no direct connection through the rock under the cut-off wall. Leakage. 95 The opening in the rock, where the leak appeared, was filled with sacks of sand which were also piled on top with the intent to throttle the flow so that the cofferdam could be pumped out. After which the leak broke out about ten feet southwest, near the edge of the cofferdam, coming up through the fill, indicating a continuation of the rock fissure in that direction. The work was then stopped. After the reservoir had been filled and when it was lowered to furnish water to the rice growers near Bay City, while its surface was falling rapidly, a strong flow of air and water mixed appeared about halfway between Huch and Wright's boat- house and the mouth of Bee Creek. It was so strong that a good sized motor boat could not be held over it, the boat each time being swept quickly aside. The flow was strong enough to raise the surface of the water two or three inches above the sur- rounding water. After about 24 hours this flow stopped and another flow, not so strong, appeared about 100 feet above the dam near the west end of the new portion. This stopped after about half a day. In Mr. Posey 's judgment this indicated that a cavern or underground passage was being emptied when the head was reversed by the lowering of the lake level or that the air and water had been confined in a cavern and the pressure was strong enough to overcome the head of water above its out- let. There was also a spring near some sheet piling about walls 17 and 18, about 30 feet from the cut-off wall, both during construction and when the water in the reser- voir was lowered. During the work on the leak in panel six the water was clear and much cooler than the water in the river but later with a slight rise in the river making the water of the stream murky the water from the leak appeared to be of the same color. Seepage in the Old Dam. Near the east end of the west portion of the old dam, where the new work joins it, the breaking away of the portion of the original struc- ture, washed out by the 1900 flood, shelled away the granite facing so that at the break one's arm could be thrust between .it and the limestone core. The mortar joints were broken in places also, so that now when the water in the lake is standing at 51 ft. or higher, the spillway face of the old dam is kept constantly wet for a dis- tance of about 125 ft. on a line which slopes to the west. The highest part is only 5 or 6 ft. below lake level and the lowest part in the neighborhood of 10 ft. above low water. The masonry above the toe is wet constantly. These conditions show that the limestone core of the gravity section is quite porous. Another evidence of the porosity of the masonry of the old dam is the fact that water stands only a few feet below the lake level in the most easterly one of the six inch well holes drilled through the dam from top to bottom and at lower levels in the other two. Class of Work. The class of work in general done by the sub-contractor was good but very rough as to finish. The forms were not held rigid to position, partic- ularly as to the crest gate piers, and consequently trouble was experienced in get- ting the crest gates fitted to place in the openings ; a great deal of chipping was 96 Report on the Dam at Austin, Texas. found necessary because of the swelling of the pier forms. The trenches for the foot- ings of the supporting walls were filled with concrete entirely, thus sealing all exca- vations of this character and helping to prevent scouring by the flood waters. Mr. Posey does not consider that the cut-off wall trench and some of those for the trans- verse walls were carried deep enough for safety at various points, although the depth was approved by the City's representative. Cofferdams. Sand and rock cofferdams were used to exclude the water from the underwater work. These were easily destroyed by slight rises in the river and were partially or entirely rebuilt thirteen times. General Amount of Pumping. A ten-inch centrifugal pump and a twelve inch dredge pump of the same type usually handled the water, but on one occasion an eight inch was needed in addition. A large pulsometer was all that was needed in the cut- off wall trench in most cases, but sometimes a smaller one of the same type and a four-inch centrifugal were also needed. Grouting. The plan of grouting relied upon to cut off the flow of water in the foundation of the dam was carried on conscientiously and as continuously as possi- ble. In one instance at least it was not effective, and Mr. Posey thought at the time the work was being done that some of the soft material in the cavities and between the hard strata was simply being compressed. If water managed to percolate through it, a larger opening could easily be made by it when under flood head. That cones of grout were formed around the grout pipes was demonstrated by holes drilled through the grout after it had hardened, but Mr. Posey believes that inverted cones of com- pressed mud were also formed between them. In other cases he thinks the grout followed the irregular cavity . where it was free to do so. Concrete. The concrete was supposed to be a 1 :2 :4 mix with the aggregate sep- arated. The engineers for the City Water Power Co. saw fit to change this to a mixed aggregate with stone or sand added as shown to be needed by voids deter- mined by means of water. If the percentage of voids ran about 24 or 25 per cent., the material was considered all right. This aggregate ran up to 2 and 2y 2 inches and down to the finest sand. Four sacks of cement were used in each yard. Mr. Posey considers the concrete mostly good above elevation 100, but below that some of it did not test out as it should have done though this was probably offset by the increase in thickness of footings and the courses immediately above them. The upstream deck was made water tight by the use of hydrated lime, and this showed exception- ally tight for all heads of water. Reinforcing. The reinforcing was carried out closer to plans than Mr. Posey ever saw attempted in large work of this character and he believes the structure to be sufficiently reinforced to withstand every strain to which it may be subjected unless the flood water head should be increased. The only walls not strongly reinforced are the cross walls supporting the dam on the inside. The bars are used here princi- pally around openings. These walls are not bonded well to the .spillway deck and Conduct of the Work. 97 make it desirable to repair the remainder of the sluiceway arches so that these walls will not get strong pressure from the inside when the sluiceways are in use. The water rises inside the dam to nearly the 30 ft. level at these times. Power House Foundations. Considerable blasting and digging were required to get the old foundations of the power house out of the way. Some of them had to be taken down to the level of the granite wall and these and the stone bluff were blasted off about four feet for the space occupied by the new turbines. The space under the old wooden floor, where space was not needed, was filled and a concrete floor built on top of this fill. No change was made in the foundation of the part of the old building left standing. Thirty-three feet were added to the length of the house. Tail Race. The tail race was not built according to plans, but was made an open channel about fifty feet wide on the bottom with a depth of five feet below low water at the end next to the draft tubes and three feet below the same level at its river end. An attempt was made to wash it out with the water from the turbines but without success. Two rises partially obstructed the channel with rock and drift and in both instances the draft tubes were blocked so that the turbines could not be used. Penstocks and Draft Tubes. The penstocks and draft tubes were built mostly out of the old tubes installed about 1893, the elbows where the penstocks connect to the turbine chambers and the elbows in the draft tubes being new. The penstocks were protected on the outside of the building by a covering of wire mesh and concrete but not on the inside of the power house. They were also treated with smooth-on and a wash of retempered cement. No leaks of consequence appeared during the test in these pipes, but on account of a failure at first to provide large enough air relief pipes the one on the east side collapsed under the north building wall and for about 30 feet each side of it. The pipe was jacked into shape and large relief pipes added. The draft tubes had to be recalked at the test to get a proper vacuum and at last some of the leaks were stopped with Portland cement. Conduct of the Work. The sub-contractor agreed, so Mr. Posey was told, to carry out the work according to a certain scheme laid down before the work was started, and on this account the excavation was commenced on the higher levels in the core wall trench when the river conditions were exceptionally favorable for work in the river. The delay caused the river work to go over into two unusually wet years when flood conditions were very bad and made the work drag along for two years longer than it should have done. No equipment for rapid excavation was on hand except two cableways, and this part of the work was slow. Concrete was first laid in wall No. 17 which was where the rock was first exposed. The entire foundation area was not exposed to inspection except the position upon which the walls actually rested. The footing forms for wall No. 17 were sunk in the sand by digging out on the inside. The concrete had to be underpinned afterwards. The rock for two panels east of wall No. 17 was washed fairly clean by sluicing and that in the "Gap" be- 98 Report on the Darn at Austin, Texas. tween walls No. 17 and No. 27 was also cleaned, but sand afterwards covered the lower portions and the forms had to settle into it. In all other cases the trenches were dug for the footings and such mateiial as could be piled up in the spaces be- tween them was so disposed of. DISCUSSION OF CONDITIONS BELCW THE TOE OP THE PRESENT DAM It is apparent that the conditions of the river bottom below or downstream from the toe of the dam were not investigated tither before the construction of the original dam in 1890-93 or prior to the reconstruction in 1911-15. The eastern part of the original dam was constructed in a wide trench excavated through the alluvial deposit that occupied more than the east half of the original can- yon of the ancient Colorado River (see Fig. 15, page 45 and Fig. 16, page 45). This deposit below the dam was gradually removed by the flood waters which were also known to be seriously eroding the rock below the dam, for these floods were con- stantly adding to the pile of rock which had formed below the dam and which is clearly shown in Fig. 23, page 52. In spite of this gradual accumulaticn, which could come from no other place except from the river bottom immediately below the dam, the City apparently made no soundings, and the condition remained unknown except from a cursory examina- tion made by Prof. T. U. Taylor who states (see W. S. & I. Paper No. 40, page 46) that he made certain soundings from the toe of the dam in March 1899, and at or near the point where the break in the dam afterwards occurred, was unable to reach the bottom at 9.5 feet below the water surface. Prof. Taylor further says (ibid page 47): "During a freshet in 1892 the overfall cut through this hard strata, tore up large pieces (some of them 10 feet long, 4 feet wide, and 2.5 feet thick and of 7 to 8 tons weight), and deposited a whole quarry in a confused and irregular pile about 150 to 200 yards farther down the river. These stones remained in that lo- cation until the big freshet of June 7, 1899, when they were carried away." Prof. Taylor further describes, in this same pamphlet, the conditions observed by Mr. J. G. Palm in 1897, as shown by Fig. 19, page 49. On the destruction of the old dam in 1900, the space below the dam was again filled by detritus from the old structure ard by the formation of bars of sand and silt; hence on the reconstruction of the dem in 1911, this space was again covered (Figs. 46 and 47). The toe of the west portion of the old dam was also covered by a deep deposit of silt (see Fig. 48) so that the condition there was unknown as will be noted from the fact that Messrs. Davis, Hill and Taylor, in their report of 1908 assumed that the toe of this section had also been undermined, for they show how repairs should be made for such a condition (see A Fig. 27, page 56). These areas were again uncovered by the floods that passed over the dam in 1915 and subsequently. On the writer's visit, soundings were taken below the entire struc- Conditions below Dam. FIGURE 45 Grouting Rock behind West Portion of Old Dam. Bottom Apparently not Exposed for Inspection. FIGURE 46 New Dam as Completed 1915, Showing Fill below Apron. Report on the Dam at Austin, Texas. FIGURE 47 New Dam Nearing Completion 1915, Showing Fill below Apron. FIGURE 48 New Dam after Completion 1915, Showing Fill below Apron. Conditions below Dam. 3.0 \ \ & G H l T02 ' Report on the Dam at Austin, Texas. E PUT N *- V sj o? ' ? \ x \ \ \ \ V, ^ o X ooo ^ Q ' ' "< I I a s 3 ^ - ii fi I 6* i 1 -c Conditions below Dam. 103 '^|i^l ) t-, 1 ^ V) 1 ^ *^^%?$ 5> ^ ^. \ ti&\\j(-ffe * e^b \ V ' ' ,/ ' ' ' / ' i \*/-^/ // n)^> i CT} / / f[ * "o/ 1 ^ v o \^_ At? i ^x 55 vS !5 ' 4 x^ N v * ^~-x II * ="$ T 1 r ^ ' x^T" " ""^^ N h 'a / ft v y * x>^ ( ^T\ / r 1 T* / T~ /T v^5Lx & n^ ^: ^ * s ^ '^ CVA 5 ! =>*! [ Q -^ ////x-" < \l,^ x^ a V *? \l(^ ' ^ ^/ *? .^P; \>^/Vo\^ i 7~ -J ~^ ' T~ ^ , j -A 1 ! r\C^8 I // ^>A lS // ^X ^ \ rl^-V> \\ UAC/ 2 \ x \ a n s' \ /NLJ ^ \~- 1//7 il ZZIfs \ ^"\\ \ * ^~\ vj Q i Q \ \ Q **> *o \ t^ I! *, ^\5 Q "N\\ *fs ^ lc> r\ y '\ Vj \V\ T " \ a K \ II =3 5 \ ^ \\ \.\\J\\ -o ^ J8 ! i \ \ \ ! \ \ V \ a ' 5 ^ 5"\ 5\ ^ 5\ 5 ? \ \ v \ ^ *\ 1 \ \ \ v -/ 1 ]i 1 c^ \ \ vr> 1 \ V IO ^ \ \ \ i 1 v. ^ \ \ \ s > 7 A\* \ ? * 1 CVJ \ \ \ N \ S?->\ 1 ^%i ] 1 2 Report on the Dam at Austin, Texas. FIGURE 60 Rock from Foundation Deposited below Dam. FIGURE 61 Rock from Foundation Deposited below Dam. Geological Conditions. 1 1 3 No. 6 was 74 Fahr., and on the same day the water at Mormon Springs was 73% Fahr., and at Barton Springs, 73y 2 Fahr. These same fissures when under pres- sure from the reservoir above the dam or from the higher waters outside of a cof- ferdam are evidently capable of absorbing water under these higher heads, trans- mit it laterally and discharge it at the lower levels ; and some of the water encoun- tered during construction probably came from these sources. In the investigation carried out by Mr. Collett, it was found that when the water above the dam was al- lowed to rise 6 feet, the water discharged from the fissure in panel No. 6 began to change in character, became cloudy and increased in temperature, showing that un- der these conditions it was beginning to discharge river water. During the writer's examination of the dam, in August, 1917, with about 15 feet of water behind the dam, the discharge was much more turbid than the river water below the dam, and the current from the panel was visible for some distance below the toe of the dam. An ideal section through Panel No. 6 and the fissure from which the leak de- veloped, is shown by Fig. 57, page 110. The water first broke through at A and under low water conditions came up through some line of weakness, AB. With high water above the dam, the fissure discharged water received into the fissure from some unknown point above the dam C, which was transmitted laterally through the weak fissure, C, D, E at an unknown depth. When an attempt was made to check the flow through A by filling the opening with sacks of sand, etc., the water broke out to the southwest at F, after which the attempt to close the leak was aban- doned for fear that conditions might be made worse before more radical and effec- tive measures were taken. It is obvious that these fault lines must extend through the dam foundation and to hundreds of feet in depth. Before the development of the fissures in panel No. 6, no spring of any considerable size had developed at the immediate dam site, but the pressure due to a full reservoir gradually developed the weakness in this fault line under the narrow cutoff wall, and has produced an opening which connects with the subterranean sources and also with the reservoir above the dam at one or more points along the fault line. There appear to be numerous lines of weakness subsidiary to the principal fault line under the structure of the dam. During the grouting of the foundation, the passage of the grout for considerable distances along these lines made them man- ifest, and those so developed and noted are described by Mr. F. S. Taylor on page 81 and are shown by the diagonal lines on the sketches on pages 82 to 85. The log of the grout holes (see pages 87 to 92) shows that the strata of the foundation limestone, at least on the east side of the stream, are interbedded with clay so soft that it was frequently expelled through the drill holes by the grout pressure from other holes where grouting operations were in progress. Much of this foundation limerock is solid and substantial, but the cracks and fissures and the , interbedded clay make it liable to destruction from water under pressure or at high 1 1 4 Report on the Dam at Austin, Texas. velocities. The condition of the solid stone can be judged from the blocks which have already been torn up from in front of the dam or under the old dam at the time of its destruction and deposited 500 feet or more below the site, where much of it still remains (see Figs. 60 and 61, page 112.) The photograph, Fig. 62, page 121, also shows the rock of the river bed which was cleared at a point just above the junction of the new dam with the west portion of the old dam during the construction work. The soluble nature of this deposit is evident from the depression in its surface. The foundation of the new dam was, however, placed in trenches excavated several feet below the surface shown. APPENDIX 5 DISCUSSION AND CKITICISMS OP THE CONDITIONS AND STRUCTURES OF THE PRESENT IN- STALLATION Essential Principles for the Construction of Safe Dams. The general princi- ples for the construction of safe dams may be briefly stated as follows : First. Dams must have suitable foundations to sustain the pressure transmitted through them. The pressure which can be safely applied to foundations varies with the nature of the material in the foundations. In good practice, the allowable pressures are usually taken about as follows : Tons per Sq. Ft. Eock equal to Best Ashler Masonry 25 to 30 Bock equal to Best Brick Work 15 to 20 Bock equal to Poor Brick Work 5 to 10 Clay in Thick Beds always dry 4 to 6 Clay in Thick Beds moderately dry 2 to 4 Second. Dams must be stable against overturning. The resultant pressures which must be provided for to safely fulfill these first two principles should take into account all the forces which will be active after the completion of the structure, and should include: The weight of the structure itself. The pressure of the water and silt impounded by the dam. The upward pressure of water which may seep under the dam. The back pressure of the tail water below the dam. These must be considered under the most severe conditions which are liable to obtain, and for safety should answer the requirement that the resultant pressure of all forces acting on the dam shall pass within the middle third of the section in order to eliminate tension in the upstream face of the structure. Third. Dams must be safe against sliding on their bases or on any section of the dam itself. To be safe from the danger of sliding, the tangent of the angle made by the re- sultant with a vertical line must be less than the coefficient of friction for the ma- terial. The coefficient of friction is about .7 for masonry against masonry or mas- onry against solid ledge rock. This means that for such conditions the angle made by the resultant with a horizontal line should not be less than 55. For a dam built I 1 6 Report on the Dam at Austin, Texas. on a foundation of clay, the coefficient of friction may, however, be as low as .35, in which case the angle of the resultant with the horizontal should not be less than 7040'. When, however, the base of the dam is built on a rough and irregular solid rock unlaminated and not interbedded with clay seams, the shearing strength of the rock is introduced and the coefficient of friction may be regarded as increased to 1.4 or more ; and if the toe of the dam abuts solid rock that can be maintained against the erosive action of floods, even a greater resistance is introduced. Fourth. Dams must have sufficient strength to withstand the strains and shocks to which they are subjected. Fifth. Dams must be practically water tight. Sixth. Dams must have essentially water tight connections with their beds and banks, and, if the bed or banks are pervious, with some impervious stratum below the bed and within the banks of the stream. In lieu of this requirement, the construction must be such that any seepage be- low or around the dam shall be forced to travel such a great distance that its head is used up in friction, and its erosive power thus destroyed. Seventh. Dams must be so constructed as to prevent injurious scouring of the bed and banks below them. The application of the above principles depends on the material from which the dam is to be built and on local conditions. The important questions at the Austin dam are: Have these requirements been fulfilled '? If they have not been fulfilled to a safe degree, what will be necessary to be done in order to secure safety? Foundation Conditions. The foundation conditions have already been described in some detail and were apparently well known to the engineers of the City Water Power Company. After the closure of the dam, Mr. F. S. Taylor, in the Engineering Record of May 29, 1915, describes the foundation conditions as follows : "The river bed for many miles up and down stream, and, in fact, practically all the underlying rock of the country, i s limestone, varying from so-called "dobe, " a disintegrated limestone, to the hardest variety. The river bed is seamed with fissures, and there are small cavities of frequent occurrence, rang- ing from a few inches to several feet in largest dimensions. These cavities are encountered sometimes as far as 20 feet below the surface of the river bed." Again, in an article in the Engineering News of June 3, 1915, Mr. Taylor writes : ' ' The river bed and the whole surrounding country are underlaid with lime- stone, which has many crevices, seams and cavities at varying depths below the surface. About 12 years ago (?), two U. S. Government engineers made a short report for the City of Austin, in which they gave an adverse opinion concerning the character of the river bottom for supporting a dam. About six years ago Foundation Conditions. 1 1 7 the City had a number of borings made to definitely determine the character of the river bed. It was then found that there were considerable amounts of broken limestone, soft limestone, cavities, seams and fissures underlying the dam, and the records obtained from these borings proved that in order to build a dam across the river at this point the defects in the strata underlying it would have to be corrected. It was decided to fill all the underlying seams and cavities with grout, and on the reconstructed river bed to build a hollow dam of reinforced con- crete of such form that there could be no uplifting force from any leakage of water under it. Furthermore, as a portion of this new section, a cutoff wall would be sunk in a trench cut in the rock on the upstream side and carried to such a depth that its lower edge would be below all permeable strata." It should be noted that Messrs. Davis, Hill and Taylor, the Government En- gineers referred to in the above extract from the Engineering News, made their re- port in 1908 and had the advantage of an examination of the core drillings made in that year and which are not now available, and in the light of such knowledge condemned the foundation at this location as untrustworthy. They advised, if this location was to be utilized, the construction of a solid dam, a core wall 20 to 30 feet or more in depth at the upper line of the dam and extending across the entire river, and the construction of a 100 foot apron below the toe of the old and new sections (see page 56). Even with these precautions they recognized the possibility of danger from deep seepage under the dam. The original specifications provided that the foundations below the dam should be made tight by grouting through drill holes (no depth specified) or by some other means (see paragraph 7, page 63). In paragraph 8 of these specifications (see page 63), as well as on the detailed drawings furnished and approved by the City's representative in May, 1912 (Drawing C-10), it was provided that "cutoff walls must be carried at least 2 feet into sound rock, which has been shown by borings to be at least 6 feet thick." Both the original and the detail plans provided for a cutoff wall in the bed of the stream both above and below the old structure. The actual construction, as described by Mr. Taylor (see Engineering News, June 3, 1915) was quite different: ''The longer part of the old masonry dam, that on the western side, was not protected by a new cutoff wall but was grouted beneath through the test holes which had been drilled on the upstream side of the section. The downstream test holes were left open as indicators of possible leakage and to release any pos- sible upward pressure from such leakage." * : "Trenches were cut in the rock to receive the wall footings, and in the bot- tom of these trenches, at intervals, drill holes were made 4 feet in depth. Where- ever these drill holes passed continuously through solid rock, the trench was ac- cepted as suitable to receive the footing. Wherever the rock was hard but a cav- ity was encountered, grout was forced into the cavity and allowed to harden be- 1 1 8 Report on the Dam at Austin, Texas. fore the footings were built upon it. Wherever soft and defective stone was found below the bottoms of the building trenches, the excavation of these trenches was continued until some point was reached below which the thickness of the good rock was at least 4 feet. ' ' The deep cutoff wall advised by the Government Engineers and indicated on the original drawings, was not constructed as noted in the above quotation, and depend- ence was placed on grouting from shallow drill holes. The holes drilled for grouting were in no case more than 12 feet in depth ; although in grouting hole No. 153, which was one of the test holes (No. 19) drilled for the City in 1908 (see page 89) and which was about 20 feet deep, 314 cubic feet of grout were used. This amount was greatly in excess of the grout taken up by any other hole in the series, and clearly indicated the presence of voids below the plane of 12 foot grouting. The record of drilling showed that not even the four feet of sound rock men- tioned by Mr. Taylor in the above extract from the Engineering News was present in all cases. For example the record shows: Hole No. 44 2" cavity at 4th foot No. 46 2" cavity at 4th foot No. 50 Drill dropped about 6" in 3d foot No. 51 Soft spot in 3d foot No. 53 Third foot soft No. 63 Soft rock in 2d foot No. 65 6" soft rock in 4th foot No. 66 6" soft rock in 4th foot No. 67 2" soft rock in 2d foot No. 69 6" soft rock in 3d foot No. 79 6" soft rock in 3d foot No. 80 1.5' soft rock in 3d and 4th foot No. 164 6" soft rock in 3d foot No. 167 Seam at 3y 2 feet No. 174 Seam at 2y 2 feet No. 177 Seam at 3V 2 feet No. 180 Water seam at 3 ft. No. 201 2 ft. solid, 8" drill dropped, 8" solid, 6" soft, li/ 2 " solid. The record of the majority of the drill holes show four feet or more of solid rock. The holes, which admitted a considerable amount of grout, are shown on the diagrams, Figs. 41 to 44, pages 82 to 85. It seems apparent from the reduction of the solid rock requirement from 6 to 4 feet that the conditions were worse than were anticipated. Grouting. Grouting has been extensively used for filling the voids back of shaft and tunnel walls, both in dry and wet work, and in sealing the cracks and fissures in Grouting Foundations. 1 1 9 rock in advance of shaft and tunnel work so as to make the shaft or tunnel excavation through such strata safer and less expensive. It has also been used to some extent for similar purposes in dam foundations but apparently with less uniform success. Its success depends on the equipment used, the extent to which the work is carried, and the care with which it is done. While it has been found perfectly feasible to force grout into the open spaces and voids of broken stone and into the open fissures and cracks in masonry and rock strata, it has been found impracticable to force the grout into seams or voids filled with sand or fine disintegrated rock unless the sand or other fine material is first washed out, leaving the void and cracks free and open. The mere passage of grout from one drill hole to another does not indicate that the entire weak strata between the two holes have been filled. Under pressure grout will follow the line of least resistance and will wash out channels and passage along such lines, appearing at considerable distances from the point of entry and yet filling only this limited channel, leaving other portions of the strata in their original condition, unfilled and still in a dangerous state. In some of the holes, during the Austin grout- ing operations (see No. 90 page 88, also No. 161 and No. 171, page 89), the pres- sure of the grout forced soft clay from adjacent cracks and drill holes, but probably removed but a small fraction of this material which lies interbedded with the lime- stone of the foundation. The grouting operations at the Austin dam are subject to several criticisms : 1st. Only one grouting cylinder was used, and the operation could not there- fore be made continuous, giving the smaller crevices a chance to clog and hence remain unfilled. 2d. The grouting at the cutoff was practically confined to a single row of holes across the river, not giving sufficient breadth of the grouted zone to give reasonable assurance of satisfactory results. 3d. The depths of the grout holes were entirely too limited for effective re- sults under the conditions. 4th. The grout used was a mixture of sand and cement, where, under the conditions at Austin, the grout should have been composed of neat cement only. Concrete, consisting of cement, sand and stone, is often used for under water work when it is deposited in mass. Grout composed of cement and sand is some- times used for work where only large cavities are to be filled ; but where small cracks and fissures are to be filled, it is found that if sand is used in the grout it is apt to separate, to clog small openings and to result in imperfect work. In some cases, grout of neat cement has been used even when masses were necessary but where the separation of the sand might endanger the results desired, as in the case of the Astoria tunnel caisson. (See Trans. Am. Soc. C. E. Vol. 80, p. 643, et seq.) The ineffectiveness of the grouting at the Austin dam is shown by the large leak that has already appeared in panel six and the smaller leak in panel four. 1 20 Report on the Dam at Austin, Texas. Deep Seepage Under and Around the Dam. Section 10 of the franchise ordi- nance (see page 59) provides that Johnson shall prevent or remedy leaks or seepage, through, under or immediately around the end of the dam, where such leaks shall materially affect the use of the water for power purposes. It is apparent that, with the reservoir full to the dam crest, a large amount of water leaks around the dam and appears in the river below. This condition is de- scribed at some length in the abstract of information by Mr. Posey (see pages 93 to 95). The approximate loss, with the reservoir full to elevation 151, is shown by the following measurements made by the U. S. Geological Survey : FLOW DATA OF COLORADO EIVEE AND BARTON CREEK (Flows in cu. ft. per second) Flow of Barton Flow at Con- Inflow between Date, Flow at dam Creek gress Ave. dam and Con- Remarks. 1916 bridge gress Ave. Aug. 29 231 32.9 337 73 4 days after reservoir was emptied Aug. 31 179 30.5 238 28 6 ditto Sept. 2 157 30.1 190 3 8 ditto Sept. 6 109 28.2 141 4 12 ditto 1917 Feb. 21 236 343 90 Reservoir filled Feb. 23 17 . 2 Assumed constant Flow at Barton Creek Feb. 21 to 23, inclusive NOTE : July 9, 1916, started to release water from the reservoir. August 26, reser- voir was emptied and normal flow allowed to pass dam until September 8, when gates were closed and water stored, and natural flow allowed to pass over crest until released in the autumn of 1917 ; 1916 discharge measurements at the dam were made about 100 feet above the structure, but the discharge measurement made at the dam on February 21, 1917, was made just above the rapids a few hundred feet below the dam. These measurements show that the inflow between the dam and Congress Street bridge, eliminating the flow of Barton Creek, was as follows : With Reservoir filled 90 cu. ft. per sec. 4 days after Reservoir was emptied 73 cu. ft. per sec. 6 days after Reservoir was emptied 28 cu. ft. per sec. 8 to 12 days after Reservoir was emptied 3 or 4 cu. ft. per sec. Deep Seepage. 121 FIGURE 62 Bed Rock above Dam near West End of New Structure during Construction. FIGURE 63 Rock at West End of Dam where Leakage occurs. 22 Report on the Dam at Austin, Texas. FIGURE 64 Rock Bluff below West End of Dam. FIGURE 65 Pervious Strata under the Forebay Wall. Deep Seepage. 1 23 It is possible that 3 or 4 cubic feet of the inflow may come from springs in the river bed, in which event the losses from seepage around the dam are apparently about 86 cubic feet per second. It is by no means certain that the above measurement represents the total loss by seepage, especially with a 65 foot head on the dam, and it is quite likely that some of the leakage finds its way into the country rock away from the river and does not augment the river flow above the gaging station. It is certain however that the loss is at least equal to the above amount. Such leakage is to be expected from the geological conditions which have been described, and while these losses may be reduced they can probably never be entirely prevented. Some of this leakage undoubtedly passes immediately around the dam, but most of it passes into the rock face of the canyon walls for a long distance above the dam, and probably travels through pervious strata and possibly fissures far back from the end of the dam. For the losses entering the side walls at considerable dis- tances above the dam, the City Water Power Company can not be held accountable, under their contract except as these losses reduce the power output below 600,000 horse power hours for each 30 day period as provided in Sec. 11 of the franchise or- dinance (see page 59). Leakage immediately around the dam occurs at the west end of the dam (see Fig. 63, page 121). Here even with the head of 15 feet, which obtained during the writer's inspection in August 1917, a considerably leakage was evident. This in- creases with higher heads and can be followed for 100 feet or more below the dam with the reservoir full, as reported by Mr. Posey. From the conditions shown in Fig. 64, page 122, it may likely follow weak strata even to greater distances below the dam. Another loss which may or may not occur immediately around the dam is mani- fest in the spring which issues under the south end of the power house. The most serious leak undoubtedly occurs through the porous strata that gave serious trouble in the original dam. The weak strata that caused the washout under the head gates (see Fig. 17, page 46), and the leaks shown in Fig. 21, page 51, are common to the entire district. These strata apparently outcrop on the east rock bluff of the river, both above and below the dam, although in general these strata are covered with soil and allvium. These porous strata absorb water from above the dam when the head waters are raised above them. Through the voids, water is readily transmitted and finds egress through cracks and fissures in the strata below the dam or through the soil that covers them. When the old dam was in use, serious losses of water occurred through these strata, and various abortive attempts were made to remedy this condition. One of these crevices through which the water was known to escape prior to 1900 is in the loose rock under the forebay wall (see Fig. 65, page 122). Others are in various 1 24 Report on the Dam at Austin, Texas. outcrops, presumably of these same strata, in Walsh's Slough (see Fig. 73, page 131) and at other known points described by Mr. Posey. (See page 94.) The Structure of the Old Dam. The broken ends of the old dam reveal a poor quality of masonry work for such an important structure. (See Fig. 74, page 131.) The interior of the dam is built of native limestone, poorly laid in cement mortar. The joints between the adjacent stones are poorly filled and it is evident from an in- spection that water under a head can readily penetrate the structure to almost every part. Holes drilled into the face of the dam during reconstruction permit water to seep out, and it was still slowly running from these holes at the time of the writer's inspection. The grouting logs (see log of holes 235, 236 and 261) show that water flowed readily into the structure and its foundations when holes were drilled into or through the apron, and that during grouting, air forced into these holes found its way en- tirely under the dam and showed above the dam. (See Mr. Posey 's evidence, page 93.) Stability of the Old Section Under Original Conditions. The principles of safe dam design construction were not so well understood or appreciated in 1890 as at present. The relations between the weight of the structure and the pressure of the impounded water, and the danger of sliding and of undercutting at the toe, were un- derstood, but the danger due to the upward pressure of water under the dam, trans- mitted through cracks and fissures in the foundation rock, was often disregarded. Uplift can sometimes be disregarded with safety on foundations which are practically impervious or where the fractures in the rock are few and small, and hence the area on which this upward pressure is exerted is of limited extent. The numerous accidents which have occurred to dams during the last twenty-five years, have emphasized the necessity of taking into account possible upward pressure, and of designing the dam with sufficient section to withstand the pressure which is likely to obtain. It has also developed, largely through the experience at Austin, that when large quantities of silt will be deposited behind a dam, that the extra pressure against the structure due to this silt must be considered in the design. In the original section of the Austin dam, the height of the crest above the rock foundation averaged about 66 feet; and while its total base width is 66 feet (see Fig. 66, page 125), the effective width for the purpose of conservative estimating and so far as resistance to overturning is concerned, is only about 42.75 feet, for it is evident that the long slender apron of the dam, built of poorly laid masonry faced with granite, would immediately break off near this point were the dam actually to overturn. According to the principles previously stated (see second principle, page 115), the resultant pressure of the force acting on the dam should pass through the base not more than 28.50 feet from the upstream face. It is evident that in the original design, the presence of clay seams was ignored, and the foundation was assumed to be solid limestone. It is also apparent that no Stability of Old Dam. 125 allowance was made in the design for silt pressure above the dam or for upward water pressure from underneath the dam, for it is found that with water at the spillway level, and with no water below the dam, the resultant pressure passes within the mid- dle third (see Fig. 66, page 125). The resultant R makes an angle of 6345', with the base, giving the value of .49 for the tangent of the angle of friction ; while any value below .7 would be considered safe for masonry on masonry or for masonry on lime- stone rock (see third principle, page 115). The dam would therefore be considered safe for the conditions assumed. W.L.E/. teo.o / 99 O? Condi f ions as Probably Original /y flssvmed. Head Wafer /eisafior> J6O O Assumed Tai/ - $4 O Si/f -None Upward Pressure FIGURE 66 Force Diagram of Old Dam with no Tail Water Upward Pressure or Silt. Condi f/ofi of o Wafer about Me Year /9OO Head Wafer /evafion - /ffO. O To// " - 99. 5//f " /22 O We/gfif af3'/tper Cu. ft. - //O. O * Upward pressure Assumed at r/ee/ of Dam -Ay// Head. * Toe S feet FIGUEE 67 Force Diagram of Old Dam with Low Tail Water Full Upward Pressure with Silt be- hind the Dam. With the conditions that actually exist at the dam site, the above assumptions are not adequate for safety. In the first place, the fractured and seamy condition of the foundation and the porous nature of the masonry admit the water pressure into and under the structure of the old dam. For safe construction, this pressure should under the present con- dition of the structure be assumed equal to the full pressure due to tlie head at the upstream face of the dam, and may be considered as decreasing to zero at the outer edge of the toe if the toe is properly drained. In the second place, with the deposition of silt against the dam, as shown by the investigations of Prof. T. U. Taylor (see Fig. 19, page 49), it is evident that the pressure due to this deposit must be considered. 1 26 Report on the Dam at Austin, Texas. These assumptions produce a very different position and angle of the resultant pressures from that evidently assumed in the original design of the dam, as will be noted from Fig. 67, page 125. This diagram shows that under these conditions the resultant pressure falls outside of the middle third of the base, and while this condition does not necessarily involve failure, it indicates an undue reduction of the factors of safety and a departure from the principles of present good practice. In the third place, the rock foundation below the apron and on the east half of the dam was in such a cracked and fissured condition and probably so interspersed with clay seams that it was rapidly eroded to a depth below the plane of the founda- tion of the dam, and the toe of the dam was undermined by the currents produced by the falling waters. In this manner, the toe resistance of the section of rock and other material below the toe of the dam was removed, the length of seepageway from above to below the dam, shortened, and the security of the dam left dependent upon the frictional resistance, which was quite likely reduced by the seepage which had developed. The probable coefficient of friction under these conditions was reduced to perhaps .4 or less, while the tangent of the angle with the resultant with the vertical was 1.01, and all factors were therefore favorable for disaster. During the flood of April, 1900, the conditions shown by Fig. 68, page 127 ob- tained. Under these conditions the resultant passed outside of the effective toe of the dam, and the tangent of the angle of friction increased to 1.23. It is also prob- able that a partial vacuum was formed on the lower side of the dam under the sheet of falling water, which would in effect add to the head above the dam; and under these conditions, failure resulted. That the old dam was stable until the resistance was removed from below its toe, and perhaps until some considerable seepage had developed underneath it, is shown by the fact that it actually stood for some seven years (from 1893 to 1900). The fact that its failure was due to the gradual developments of weakness in the foundation seems established by the fact that the western portion of the dam, where the ma- terial below the toe was more resistant and was not removed by the impact and en- ergy of the flood waters (see soundings on pages 101 and 104) still stands, although some seepage had undoubtedly developed in that section as well. It is nevertheless true that the section of the old dam even with the rock below the toe intact, has too low a factor of safety and is in an unsafe condition. The Use of the Old Section for the Neiv Conditions. The new conditions, under which the remaining part of the old dam constitutes about half of the reconstructed dam, are described by Mr. F. S. Taylor in the Engineering Eecord of May 24, 1915, as follows : "In order to get the proper amount of power and lake storage, the water level would have to be raised from the old elevation of 60 feet to 65 feet above low water, which meant that with 11 feet of water over the crest during flood, the maximum water level would be 76 feet above the low water instead of 71 Stability of Old Dam. 127 feet. The portion of the old section which had given way failed under a 71 foot water level, and it was imperative that the portion of the old section remaining should not be subjected to as great stress as it had previously withstood. This required that the maximum water level should never rise even as high as 71 feet above low water. It appeared as if these two conditions could not be reconciled. However, after considerable study, a type of crest gates * * * was adopted. "With this arrangement, the new section of dam was built only 51 feet high from low water to crest, or 9 feet lower than the old section. The crest gates WLt\ mOf W.L&. I6S.O 66.O'- Cond/ttons at Time of /9OO Fai/ure Head Wafer /eraf/on - /?/ O To// - We/aht of Si/t per Ca ft - //O. O # Upward Pressure assumed of- flee/ of Oa/n - fo>/ rfead. Toa ' 24 f-ff* FIGUBE 68 Force Diagram for Old Dam under the Conditions at Time of Failure. Condition of iow Wafer tv/M Gates, tieod Water /er at/on /65 O Tot/ 99. SS/t ' Worte Upward Pressure Assumed at Heef of Dam - /*/// Head Toe - ' 5 feet FIGURE 69 Force Diagram for Old Dam with Gates under Low Water Conditions. on the old section are 6 feet high, and those on the new section, 15 feet, so that the upper edges of the crest gates are all at the same level, 66 feet above low water. * * # "It is estimated that with a discharge of 200,000 second feet, the thickness of the water over the crest of the new section will be 18 feet, and over the old section 9 feet. This means that the present dam will pass 50 per cent, more water than did the old dam when it failed, but the elevation of the water in only 9 feet above the crest of the old dam, while it was 11 feet above the crest when the weak section went out in 1900." Under the new conditions it will be noted that five feet of head are added to the water behind the old section by the installation of crest gates. It was apparently 128 Report on the Dam at Austin, Texas. the theory of the design that silt could be kept away from the back of the dam by the use of sluice gates. It is the opinion of the writer that silt cannot be drawn from behind the old section by the flow through these sluice gates, and that for safety a height of silt even greater than that which had accumulated above the old dam at the time of its destruction should be assumed behind the old section. The old section has therefore been analyzed for the following conditions, with the results shown : 1. For no Silt and Low Water Conditions (see Fig. 69, page 127). The resultant passes dangerously near the toe of the effective section, and the tangent of the W.I /. /69. WL& I65.O Conditions of Low Wafer with- Gates ana Probable Maximum SiM r/ead Wafer Elevafion - J65.O To/7 - . 99.O Si It ' /45.0 Weight of Sift per Ct/ ft - //O. O* Upward pressure assumed a/ rfee/ of Pan? - Fu// rfead. " - Toe - > 5 r~eef. FIGURE 70 Force Diagram for Old Dam with Gates under Low Water Conditions and with Silt behind the Structure. Conditions of Ord/narg 9' F/ood over Spillway with Probable Maximum 3i/f. Head Water F/e ration - /69.O To// " H- - /2av of oarfon Sprmq Seepage, Evaporation and f~/o>r of Barfon Sprino - x x X Xix X x x x vXi*. KX x x* v x" K x January eefafrona of rtijdrou/fc RaMrr. fohefooe and necessary 0vxi'//ary Sfron rr fo Moi"t>'"' ffSO Continuous fforst foirrr under 6JS f&ff Head. Seepage, etc. fbndyqe- ffltxit/crry Steam. FlGUBE 85. 52 Report on the Dam at Austin, Texas. S/orn 1650 /Z45 735 320 1650 4l?0 zoo y////. Teenage, Evaporation and f/ovr lL*.^X-^^.>i>.tXXXAXX*lxXA 19/4 >650 | ,245 \ 320 ZOO &I6 /650 #45 780 31O O Sce/xige, Evaporation ono' f~/o>v of Barfoi* \ \ i Spring. January February rJarc/i t fff>r/7 May June Ju/y &uyusS- September October firveoseaPr/s or cct-oe&oo G/VF& ar fojsr/tj, Texas. fjptver fo rfo/frfo/n S65O Gpn/rwotjs fforsf ftonvr under ffS feet fleacr 1 . November December. '////////// X>VVVVVVVVV ^$$^$ Sef/ooye. etc. fftfxt/i'aro Stean FlQUBE 86. Power Calculations. 153 Showing the amount of hydraulic power, in thousands of horse power hours, which could have been delivered with a 65 foot head by the Austin hydraulic power plant at the switchboard, and the amount of steam power necessary to maintain 1650 continuous horse power during the years 1898 to 1917, inclusive. Year Jan. Feb. Mch. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual Hydraulic 1 235 1 1% 1 235 1,196 1,235 1,235 1,196 1,235 971 1 004 11 738 189S Steam o o o o o o 225 231 456 Total 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,1% 1,235 12,194 Hvdraulic 994 906 995 1,041 1,235 1,196 1,235 1,235 1,196 1,235 1,1% 1,235 13, 699 1899 Steam 241 211 240 155 o 847 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,196 1,235 13, 546 Hydraulic 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,1% 1,235 14,546 1900 Steam o Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,196 1,235 14,546 Hydraulic 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,196 1,235 14,546 19O1 Steam o o o Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Plydraulic 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14, 546 1902 Steam o o Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,196 1,235 14, 546 Hydraulic 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 1903 Steam o Total 1,235 1,117 1,235 1, 193 1,235 1,196 1,235 1,235 1,1% 1,235 1,196 1,235 14,546 Hydraulic 1 235 1 156 1 235 1 196 1 235 1,196 1,235 1, 235 1,196 1,235 1,196 1,235 14,585 19O4 Steam Total 1,235 1,156 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,196 1,235 14,585 Hydraulic 1,235 1,117 1 235 1 196 1,235 1,1% 1,235 1,226 1,187 1,235 1,057 865 14, 019 1905 Steam o 9 9 139 370 527 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Hydraulic .... 875 802 914 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,196 1,235 13,550 1906 Steam 360 315 321 996 Total 1,235 1,117 1,235 1 196 1 235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Hydraulic 720 645 710 706 1 162 1,196 1,230 1,191 1,162 1,235 1,196 1,235 12,388 1907 Steam 515 472 525 490 73 5 44 34 2,158 Total 1,235 1,117 1,235 1,196 1 235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Hydraulic 1,235 1,156 1 235 1 196 1 235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,071 14,421 1008 Steam o o 164 164 Total 1 235 1 156 1 235 1 196 1 235 1,196 1,235 1,235 1,196 1,235 1,196 1,235 14,585 Hydraulic 976 867 961 937 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 13,504 1909 Steam 259 250 274 259 o 1,042 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Hydraulic 1,235 1,117 1,235 1,196 1,235 1,066 1,090 1,090 1,133 1,148 836 846 13,227 1910 Steam o 130 145 145 63 87 360 389 1,319 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Hydraulic 851 935 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,220 1,181 1,230 13,945 1911 Steam 384 182 15 15 5 601 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14, 546 Hydraulic 1 235 1 156 1,235 1 196 1,235 1,196 1,235 1,235 1,196 1,235 981 3.004 14,139 1912 Steam 215 231 446 Total 1,235 1,156 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,196 1,235 14,585 Hydraulic 1 038 931 1,024 1,013 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 13,769 1913 Steam 197 186 211 183 777 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14,546 Hydraulic 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,196 1,235 14,546 1914 Steam Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14, 546 Hydraulic 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,196 1,235 14,546 1915 Steam Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 1,1% 1,235 1,1% 1,235 14, 546 Hydraulic 1,235 1,156 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 927 928 14,009 1916 269 307 576 Total 1,235 1,156 1,235 1,196 1,235 1,196 1,235 1,235 1,196 1,235 1,196 1,235 14,585 80S 1 091 1 196 1 048 980 7,898 QA7 298 144 o 187 255 1,776 Total 1,235 1,117 1,235 1,196 1,235 1,196 1,235 1,235 9.674 Total 21, 202 19,475 22, 822 22,535 24,483 23,790 24,363 24, 247 22,618 23,363 21,501 21,768 272,157 Hyd'ic Period 19 19 20 20 20 20 20 20 19 19 19 19 19.6 Average 1,116 1,024 1,141 1,127 1,224 1,189 1,218 1,212 1,190 1,230 1,131 1,146 13, 980 Total 2,263 1,894 1,878 1,385 217 130 337 453 106 102 1,223 1,697 11,685 Steam Period 19 19 20 20 20 20 20 20 19 19 19 19 19.5 Average 119 100 94 69 11 7 17 23 6 5 65 89 598 Hydraulic Steam 1,116 119 1,024 100 1,141 94 1,127 69 1,224 11 1.189 7 1,218 17 1,212 23 1,190 6 1,230 5 1,131 65 1,146 89 13,980 598 Total 1,235 1,124 1,235 1,196 1,235 1.196 1,235 1,235 1,196 1,235 1,196 1,235 14, 578 t Hydraulic .. Steam 90.4 9.6 91.1 8.9 92.4 7.6 94.2 5.8 99.1 0.9 99.4 0.6 98.6 1.4 98.1 1.9 99.5 0.5 99.6 0.4 94.6 5.4 92.8 7.2 95.9 4.1 154 Report on the Dam at Austin, Texas. 320 * <3OO POO 600 4OQ 200 400 ZOO 600 .fc ZOO eoo 4OO :'^^^ -^88888^ 888^8 88888^ Seepage, frojooraf/ov onaf f/oir of Sorfon Spring - (s * May June Ju/if Sepfember October Movemiier December or ofrofta of rftfCfrovt'o f&vrtr, ftonc/oy* ortcf nece*9on/ Gt*e//f&ry Sfeom to My/ri 'for'fr /6SO Gyr>tiinv0u9 Horye Power (/rraffr 60 feef ffeao 1 Serjoaye. era. FlGUBE 87. ary 3 f earn Power Calculations. 55 too /650 $ 600 I ZOO 6OO 4OO ZOO 400 zoo , '//////, Y/////, W////, Y////// 7/77 //, Seepage, evaporation and f/ov of 3arfon Spring) < XXXXAx1>Ay\y^xNXXX XXXXXXXXAAXXXX K///A Y//////AY/////Y/////M eepage, Eva/oorartofr and f/of of Barfon Spring >(XXxW^vV .AAAXXX*. X Seepage, Fvapo/~cr//of? and F/ow of Sarfon 5pr Y///////////S Seepage, Cvaporafion crnal f/oir of Barfon Spring. k ' Seepage, ^aporof/on ana> f/o Of Barton Spring September October November December January february March ffpri/ 32O ring ff*/ationa of Hya'rou/'c Reiver, f&ndaae and necessary 0vxi//ary Sfeon? Power to sfainfoin /f0 Confihvota fforae nurtr under 60 fee/ Mead. FIGURE 88. 56 Report on the Dam at Austin, Texas. 6OO 400 eoo 1918 /650 IZ4S 706 320 O Sf ** fya ' yorat/on or* * /%> of 7 January February ffjsri/ Mat/ */u/?ff jfc'/y fft/qu&t 3e/?Aes??6er 0G/06er Mere/rro*/- 0ecem*er. OF COIO2APO &/V&2 0T avST/N t 'ona'a&e arrd rtfCf-Ayffr-y &u*/ ffor&e &0>*w (Sf*c/fr 00 feef Ponc/ay*. FlGUBE 89, Power Calculations. 157 Showing the amount of hydraulic power, in thousands of horse power hours, which could have been delivered with a 60 foot head by the Austin hydraulic power plant at the switchboard, and the amount of steam power necessary to maintain 1650 continuous horse power during the years 1898 to 1917, inclusive. Year Jan. Feb. Men. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual Hydraulic 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,076 765 757 11,116 1898 158 429 477 1,064 Total 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 12,180 Hydraulic 748 673 757 880 1,234 1,194 1,234 1,040 832 908 1,194 1,234 11,928 1S99 Steam 486 442 477 314 194 362 326 2,601 Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14, 529 Hydraulic .... 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14, 529 190O o Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14, 529 Hydraulic 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 1901 Steam Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,523 Hydraulic .... 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 1902 Steam Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 Hydraulic 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,110 1,075 14,286 1903 84 159 243 Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 Hydraulic 1,101 1,025 1,102 1,098 1,234 1,194 1,234 1,234 1,194 1,234 1,083 1,058 13,791 1904 133 127 132 96 . 111 176 775 Total 1,234 1,115 1,234 1,194 1^.234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,566 1,043 944 1,186 1,194 1 234 1,194 1,234 1,172 1,129 1,234 956 583 13,108 1905 Steam 191 171 48 62 65 238 646 1,421 Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,23' l,19i 1,234 1,194 1,234 14,529 Hydraulic 575 514 659 1,159 1,234 1,194 1,234 1,234 1,194 1,141 1,070 1,186 12,394 1906 Steam 659 601 575 35 93 124 48 2,135 Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14, 529 455 395 437 430 1,110 1,194 1,221 743 614 1,234 1,194 1,234 10,261 1907 Steam 779 720 797 764 124 13 491 580 4,268 Total 1,234 1,115 1,234 1,194 1,233 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14, 529 1 234 1,152 1,234 1,194 1, 234 1,104 1,234 1,234 1,194 1,234 1,194 996 14,328 1908 Steam 238 238 Total 1,234 1,152 1,234 1,194 1,234 1,194 1,234 1,23' 1,194 1,234 1,194 1,234 14,566 Hydraulic 721 567 617 633 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 12,290 1909 513 548 617 561 -Q 2,239 Total 1 234 1 115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 Hydraulic 1,004 881 987 1,194 1, 234 765 730 730 1,003 1,062 543 530 10, 667 1910 Steam 230 230 247 429 504 504 191 172 651 704 3,862 Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 Hydraulic 531 787 1,234 1,194 1,097 756 995 1,234 1,194 818 694 1,013 11,547 1911 Steam 703 328 137 438 239 416 500 221 2,982 Total 1,234 1,115 1,234 1,194 1,234 1.194 1,234 1,23' 1,194 1,234 1,194 1,224 14,429 Hydraulic 1,102 1,073 1,234 1,194 1,234 1,194 933 916 880 1,070 788 801 12,419 1912 132 79 301 318 314 164 406 433 2,147 Total 1 234 1,152 1,234 1,194 1,234 1,194 1,234 1,23' 1,194 1,234 1,194 1,234 14,566 Hydraulic 801 731 810 804 1,234 1.194 1,190 983 1,061 1,234 1,194 1,234 12,470 1913 Steam 433 384 424 390 44 251 13? 2,059 Total 1 234 1 115 1,234 1,194 1,234 1,194 1,234 1,23' 1,194 1,234 1,194 1,234 14,529 Hydraulic 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 1914 Steam Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,23' 1,194 1,23' 1,194 1,234 14,529 Hydraulic 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,529 1915 Steam Total 1,234 1,115 1,234 1,194 1,234 1,194 1,234 1,23' 1,19< 1,23' 1,194 1,234 14,529 Hydraulic 1,234 1,152 1,234 1,194 1,234 1,194 1,225 900 867 1,026 752 708 12,720 1916 Steam 9 33' 327 208 442 526 1,846 Total 1 234 1 152 1,234 1,194 1,234 1,194 1,234 1,23' 1,194 1,23' 1,194 1,234 14,566 717 647 712 690 1 000 1,194 650 374 5 974 1917 Steam 517 468 522 504 234 584 860 3,689 Total 1 234 1 115 1 234 1 194 1,234 1,194 1,234 1,234 9,663 Total 18,670 17,235 20, 841 21,21)6 24, 185 23, 013 22,986 21, 666 20,714 21,909 19,701 19, 818 251, 954 Hyd'ic Period 19 19 20 20 20 20 20 20 19 13 19 19 19.5 983 906 1,042 1,061 1,209 1,151 1,149 1,084 1,090 1,153 1,037 1,043 12,921 Total 4,776 4,098 3,839 2,664 495 867 1,694 3,014 1,972 1,537 2,985 3,628 31,569 Steam Period 19 19 20 20 20 20 20 20 IS IS 19 19 19.5 Average 251 215 192 133 25 43 85 150 104 81 157 191 1,617 Hydraulic Steam 983 251 906 215 1,042 192 1,061 133 1,209 25 1,151 43 1,149 85 1,084 150 1,090 104 1,153 81 1,037 157 1,043 191 12,921 1,617 Total 1 234 1 121 1 234 1 194 1,234 1,194 1,234 1,234 1,194 1,234 1,194 1,234 14,538 t Hydraulic .. Steam 79.7 20.3 80.8 19.2 84.5 15.5 88.8 11.2 98.0 2.0 96.4 3.6 93.1 6.9 87.8 12.2 91.3 8.7 93.4 6.6 86.8 13.2 84.5 15.5 88.9 11.1 1 58 Report on the Dam at Austin, Texas. head at 65 rather than at 60 feet with a development of 1650 horse power, but that if the annual cost is equal to or greater than this amount, there will be no logical rea- son for the increased head. Interest should be taken at 5 per cent. The annual cost of maintenance and the depreciation of such gates can hardly be taken at less than 10 per cent. The capi- talized annual saving due to a 65-foot head may therefore be estimated on a 15 per cent, basis at $61,140. To this should be added the cost of raising the crest to eleva- tion 160 feet, which is estimated at $53,000, making a total of $114,140, which is the maximum that can be expended to advantage for increasing the head from 60 to 65 feet, with a capacity of 1650 horse power. Study of the Development of 3300 Continuous Horse Power. The ultimate de- velopment of the power plant at the Austin dam as now designed anticipates the output of 3300 horse power. This condition has also been investigated for both 65 and 60 foot heads. Development of 3300 Horse Power Under 65 Foot Head. The conditions that will obtain under a 65-foot development and a continuous output of 3300 horse power are shown on pages 159 to 163 inclusive, and the detailed estimates are shown on page 164. Development of 3300 Horse Power Under 60 Foot Head. The same studies for a 60-foot development are shown on pages 165 to 169 inclusive, and the detailed esti- mates are shown on page 170. Comparison of 65 and 60 Foot Heads for the Development of 3300 Continuous Horse Power. Abstracting the table for 65 and 60 foot heads, the total horse power hours per year are found to be approximately 29,200,000, and the comparisons to be as follows: HPH Water HPH Steam Average at 60 Foot Head 21,300,000 7,900,000 Average at 65 Foot Head 23,290,000 5,650,000 Average Annual Difference in Amount of Steam Power Used . . . 2,2 50,000 HPH Average Annual Value of Steam Power at 0.9c per Horse Power Hour $20,250.00 With interest at 5 per cent, and depreciation and maintenance at 10 per cent, the capitalized value of the extra 5-foot head is essentially $135,000. To this, for com- parison, should be added the cost of removing piers and building up the hollow sec- tion to 60 feet, amounting to $53,000, and making the total difference in favor of the 65 foot dam $188,000, which is the total amount which can now be expended to secure the extra 5-foot head. To make the 65-foot head profitable, the expense should be less than the amount named as with this expenditure the returns would equal only the estimated annual expense. Power Calculations. 159 850 350 January February March ffpri/ May Ju, Sep/ember October A/ore/nber December e/vee #T flusr/N, Texas. Sfream f/on-. e. efc- Pondoqe FlQUBE 90. y S/eym. 160 Report on the Dam at Austin, Texas. Setfioae. Evaporation and f/o# of Sorton Spring. 350 January fetwary Marcri ffpr/'J May June Ju/tf fiuo/us/ Sepfffntef' Ocfo&er Movembtr Of Seepage, tfo. FlQUBE 91. Power Calculations. 161 3300 Z35O I860 850 350 January February March ffpri/ May June July august September October November Cecemder OF COLOgfiPO e/V ffr ffUST/M, Onrtno getatioru of fftfafrais/fc Power. Poncfage &*& neccasory Gux/'/t'ary Po#er fo M0/'rjfa'/r> 33O0 Corrfinuoos fforse Pother vna/er C5 ffffff Sfeao. Sfreom F/o>v. 3ec.?J?f. efo. POncfaye FIGURE 92. 162 Report on the Dam at Austin, Texas. .'000 zoo 8OO 600 4OO 850 350 January Fttwi/orij rlorcn 0pri/ September October November December _ 0/vre ar ausr/N, Tfxas. Sftoirinq Ke/attoru of Hyc/roulic Ftonrer, Ponctaqe or>& necessary av*i/iory Steart Power to Maintain 33OO Continuous Hone Po*tr urx/tr fi feet Mead Stream rtov 3ee/aaiff. rfc avxi//onf Steam FlQUBE 93. Power Calculations. 163 3300 ^lOOO SOO 4OO January February flpri/ May June Ji/ty of coweapo n33OO Sepfember Ocfoder Movem&er December FIGURE 94. 164 Report on the Dam at Austin, Texas. Showing the amount of hydraulic power, in thousands of horse power hours, which could have been delivered with a 65 foot head by the Austin hydraulic power plant at the switchboard, and the amount of steam power necessary to maintain 3300 continuous horse power during the years 1898 to 1917, inclusive. Year Jan. Feb. Men. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual Hydraulic 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,160 295 2,455 2,455 2,455 2,455 2,455 2,417 38 2,455 2.10S 347 2,455 2,161 294 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,762 693 2,455 2,37: 2,375 2,375 2,375 2,375 2,375 2,37 2,37 2,37 2,37 2,37 2,375 2,375 2,375 2,37a 2,375 2,375 2,375 2,375 2,375 2,375 2,375 2,375 2,375 1,089 1,286 2,375 1,352 1,023 2,456 2,45 2,45 2,45 2,455 2,45 2,455 2,455 2,45 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,455 2,267 188 2,455 2,455 2,455 2,455 2,455 1,100 1,355 2,455 1,802 653 2,455 1,322 1,133 2,455 1,955 500 2,455 2,455 2,455 2,455 2,455 1,850 605 2,455 1,355 1,100 2,455 2,45 2,455 1,48 96 2,45 2,45 2,45 2,455 2,455 2,45 2,455 2,455 2,455 2,455 2,455 1,951 2,375 2,375 1,248 1,127 2,375 2,375 2,375 2,375 2,375 2,375 2,375 2,375 2,375 2,375 2,375 1,616 759 2,375 2,375 2,375 1,208 1,167 2,375 2,375 2,375 2,375 2,375 1,430 945 2,375 1,982 393 2,375 1,257 1,118 2,375 2,063 307 2,375 2,375 2,375 2,375 2,375 1,295 1,080 2,375 1,230 1,22 2,45 1,47 98 2,455 2,45 2,45 2,45 2,455 2,455 2,455 2,176 27 2,455 2,455 2,455 1,677 778 2,455 1,855 600 2,455 2 311 97 1,40 2,37 2,37 2,37 2,37 2,37 2,15 22 2,37 2,37 2,37 1,419 958 996 1,458 2,455 2,455 2,455 2,455 2,455 1,802 653 2,455 2,455 2,455 1,455 1,000 2,455 1 QOQ 15,311 4,089 19, 400 20, 642 8,263 28.905 28, 905 28,905 28,027 878 28, 905 27, 377 1,528 28, 905 26, 670 2,235 28,905 23,109 5,871 28, 980 21,517 7,388 28,905 21,666 7,239 28, 905 19,071 9,834 28, 905 26, 538 2,442 28,980 22,902 6,003 28,905 17,191 11,714 28, 905 20.992 7,913 28,905 18,982 10,098 28,980 21,810 7,095 28,905 28,905 28,905 28,905 28,905 21,628 7,352 28,980 10,038 9,207 19,245 1898 Steam ; Total ' Hydraulic 995 1,460 2,455 2,455 2,455 2,455 2,455 1,801 654 2,455 2,455 2,455 1,383 1,072 2,455 1,400 1,055 2,455 750 1,705 2,455 698 1,757 2,455 2,348 107 2,455 914 1,541 2,455 1,413 1,042 2,455 835 1,620 2,455 1,781 674 2,455 1,027 1,428 2,455 2,455 2,455 2,455 2,455 2,311 144 2,455 928 1,527 2,455 898 1,322 2,220 2,220 2,220 2,220 2,220 1,643 577 2,220 2,220 2,220 1,282 1 013 l.OOC 1,45 2,45 2,456 2.4K 2,455 2,455 2,177 278 2,455 2,455 2,455 1,383 1,072 2,455 1,937 518 2,455 818 1,637 2,455 707 1,748 2,455 2,345 110 2,455 865 1,590 2,455 1,418 1,037 2,455 2,455 2,455 1,777 678 2,455 1,027 1,428 2,455 2,455 2,455 2,455 2,455 2,267 1?8 2,455 923 1,532 2,455 1,42 95 2,37 2,37 2,37 2,37 2,375 2,356 18 2,375 2,375 2,375 1,578 797 2,375 2,375 2,375 1,680 695 2,375 6SO 1,695 2,375 2,327 48 2,375 945 1,430 2,375 2,375 2,375 2,375 2,375 2,040 335 2,375 1,085 1,290 2,375 2,375 2,375 2,375 2,375 2,375 2,375 887 1,488 2,375 1809 Steam Total Hydraulic 1900 Steam Total Hydraulic 1901 Steam Total Hydraulic 1902 Steam Total i Hydraulic 1903 Steam Total Hydraulic 1,520 855 2,375 1,257 1,11 2,375 1,665 710 2,375 2,375 2,375 1,737 638 2,375 2,375 2,375 1,550 825 2,375 1,165 1,210 2,375 970 1,405 2,375 2,375 2,375 2,375 2,375 2,375 2,375 965 1,410 2,375 1904 Steam 1,062 2,455 755 1,700 2,455 2,100 355 2,455 2,455 2,455 1,003 1,452 2,455 2,455 2,455 855 1,600 2,455 1,858 597 2,455 1,023 1,432 2,455 2,455 2,455 2,455 2,455 2,455 2,455 928 1,527 2,455 ; Total 2,295 1,264 956 2,220 683 1,537 2,220 635 1,585 2,220 2,208 87 2,295 778 1,442 2,220 1,295 924 2,220 1,355 865 2,220 1,670 625 2,295 933 1,287 2,220 2,220 2,220 2,220 2,220 2,165 130 2,295 837 1,383 2,220 Hydraulic 1905 Steam 504 2,455 2,455 2,455 1,200 1,255 2,455 2,455 2,455 2,455 2,455 1,096 1,359 2,455 2,455 2,455 1,397 1,158 2,455 1,600 855 2,455 2,455 2,455 2,455 2,455 1,354 1,101 2,455 971 1,484 2,455 Total Hydraulic 1906 Steam Total Hydraulic 1907 Steam 144 Total 2,455 2,455 2,455 2,455 2,455 1,152 1,303 2,455 1,250 1,205 2,455 1,622 833 2,455 2,455 2,455 2,455 2,455 2,455 2,455 1,719 736 2,455 Hydraulic 1908 Steam Total ' Hydraulic 1909 Steam Total Hydraulic 1910 Steam Total Hydraulic 1911 Steam Total 2,375 1,962 413 2,375 2,375 2,375 2,375 2,375 2,375 2,375 1,944 431 2,375 2,375 2,375 1 Hydraulic .... 1912 Steam Total Hydraulic 1913 Steam Total Hydraulic 1914 Steam Total Hydraulic 1915 Steam Total ' Hydraulic 1916 Steam Total Hydraulic 1917 Steam Total Total 30, 859 19 1,623 15,786 19 832 1,623 832 2,455 66.1 33.9 28,746 19 1,513 13,733 19 723 1,513 723 2,236 67.6 32.4 33, 374 19 1,757 13,271 19 698 1,757 698 2,455 71.5 28.5 36,377 19 1,915 8,748 19 460 1,915 460 2,375 80.6 19.4 47,433 20 2,372 1,667 20 83 2,372 83 2,455 96.6 3.4 44,347 20 2,217 3,153 20 158 2,217 158 2,375 93.3 6.7 43,566 20 2,178 5,534 20 277 2,178 277 2,455 88.7 11.3 40, 517 20 2,026 8,683 20 434 2,026 434 2,460 82.3 17.7 38, 229 19 2,012 6,896 19 363 2,012 363 2,375 84.7 15.3 38,561 19 2,029 8,084 19 426 2,029 426 2,455 82.6 17.4 34,368 19 1,808 10,757 19 567 1,808 567 2,375 76.1 23.9 33,808 19 1,779 12,837 19 676 1,779 676 2,455 72.4 27.6 450,185 19,333 23,290 109,149 19,333 5,650 23,290 5,650 28, 940 80.5 19.5 Hyd'c Period ' Average | Total Ste'm Period Average 1 Hydraulic i Total I % Hydraulic i % Steam Power Calculations. 165 Seepage, Evaporation ancf /"Sow of Borfcm Spring Septemtw October SS i/emt>er Oecemtier January Stream f/prr. Sffpoar, ere. FIGURE 95. 166 Report on the Dam at Austin, Texas. 1200 Y////////// Y///Y//////////////////, Y/W//////////, 735 At/aus/ September Oc/oeer or coweaoo eiYte tfrrJusr/N, Texas. fr/afior>f -of rfyctroo/ic fbirrr, fbniSoor and ntcessoru 0u*i'//or ffprit May -TS5 miiy eefaftor*3 of rtyctraut/c tforrfr. Penc/aqrr one? fteceasortf GtsMtttory Sffa PQ~rr to rloinfoin 33OO CQnftnvOv^ ' fforsc Poirer an&er 6O reer Heoc/, See/serge, ete. forto/ayf ffvf/7/ary Sfrar*. FlQUBE 97. 168 Report on the Dam at Austin, Texas. SttOHrmy &*/a*i0n6 of flydratstic &O"*', Poic/ay* or>& "rcessory **vxf"ary j Pother fo /*fo*s>fQ/r7 330O Cont?vOu3 Morse f*ower under feet rteact. rtcfo?* as>& r>*ce&sortj 0tSJ(i//'ortf $fifo Seepage, efc "ana/age Power Calculations. 169 February March April May June Ju/y 3ef>f-emi>er October JVovemter Oecemhtr winq Gelations of rtyCfrauhc Power, Forrdotfe ana/ r>ecf&3ori/ 0tfjr/t/arrc/ J Power fff -rto-infairt 33OO Corrfirtvoua rforje Porver uncftr 60 feet r/faot Seepage, efc. Pyno/aqe OuxWarif Sftam, FlGUEE 99. 170 Report on the Darn at Austin, Texas. Showing the amount of hydraulic power, in thousands of horse power hours, which could have been delivered with a 60 foot head by the Austin hydraulic power plant, at the switchboard, and the amount of steam power necessary to maintain 3300 continuous horse power during the years 1898 to 1917, inclusive. Year Jan. Feb. Mch. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual Hydraulic 1,134 1,878 2,480 2,400 2,230 1,945 2,020 1,140 764 764 16 755 1898 Steam 1,346 522 250 535 380 1 340 1 636 1 716 7 7 9 5 Total 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2,400 2 480 24 480 Hydraulic 750 697 754 1,275 2,480 2,400 2,480 1,193 880 1,044 2,320 2 480 18 753 1899 Steam 1 730 1,543 1,726 1,125 1,287 1,520 1 436 80 10 447 Total 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2,400 2 480 29 200 Hydraulic 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2 400 2 480 29 200 19OO Steam o o o o o Total 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2,400 2 480 29 200 Hydraulic 2,480 2,240 2,480 2,400 2,480 2,016 2,165 1,935 2,080 1 802 1 906 1 417 25 401 1901 Steam 384 315 545 320 678 494 1 063 3 799 Total 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2 400 2 480 29 200 1902 Hydraulic Steam 1,432 1,048 1,275 965 1,898 582 2,300 100 2,480 2,072 328 2,480 2,480 o 2,400 o 2,076 404 1,823 577 2,480 o 25,106 4 004 Total 2 480 2,240 2,480 2,400 2,480 2,400 2,480 2 480 2 400 2 480 2 400 2 480 29 200 Hydraulic 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,352 2 295 2 126 1 126 1 080 25 939 1903 Steam c 128 105 354 1 274 1 400 3 261 Total 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2 400 2 480 29 200 1904 Hydraulic Steam 1,087 1,393 1,050 1,270 1,126 1,354 1,432 968 2,480 2,400 2,440 40 2,240 240 2,355 45 2,480 1,260 1,140 1,060 1 420 21. 410 7 870 Total 2,480 2,320 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2 400 2 480 29 280 1905 Hydraulic Steam 1,043 1,437 955 1,285 1,850 630 2,400 2,480 2,400 2,480 1,637 843 1,282 1 118 1,544 936 1,278 1 122 570 1 910 19, 919 9 281 Total 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2 480 2 400 2 480 29 200 1906 Hydraulic Steam 627 1,853 560 1,680 685 1,795 1,600 800 2,080 400 2,400 2,480 2,480 2,400 1,418 1,062 1,075 1 325 1,900 580 19, 705 9 495 Total 2,480 2,240 2,480 2,400 2,480 2,400 2,480 2,480 2 400 2 480 2 400 2 480 29 200 1907 Hydraulic Steam 460 2,020 390 1,850 440 2,040 428 1,972 2,129 351 2,400 2,280 200 743 1,737 640 1,760 2,310 170 2,400 2,458 22 17,078 12 122 Total 2 480 2,24 2,480 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2,400 2 480 29 200 1908 Hydraulic Steam 1,910 570 1,84 480 1,855 625 2,115 285 2,480 2,400 2,480 2,480 2,400 2,480 1,605 795 775 1,705 24,820 4 460 Total 2 480 2,32 2,48 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2,400 2,480 29 280 190 Hydraulic Steam 610 1,870 56 1,68 625 1,855 710 1,690 2,480 2,400 2,480 2,46 13 2,360 4 2,480 2,400 2,480 22,052 7,148 Total 2,480 2,24 2,48 2,400 2,480 2,400 2,480 2,480 2,400 2,480 2,400 2,480 29, 200 191 Hydraulic Steam 1,013 1 467 883 1,35 97 1,507 2,320 8 2,267 213 77 1,624 742 1,738 73 1,744 1,28 1,112 1,070 1,410 527 1,873 533 1,947 13, 128 16, 072 Total 2,48 2,24 2,48 2,400 2,480 2,400 2,48 2,48 2,400 2,480 2,400 2,48 29,200 191 Hydraulic Steam 51 1,96 1,17 1,06 1,97 50 2,32 7 1,952 528 77 1,62 1,48 994 2,31 16 1,94 453 826 1,65 69 1,707 1,62 855 17,609 11, 591 Total 2,48 2,24 2,48 2,400 2,480 2,400 2,48 2,48 2,400 2,480 2,400 2,48 29,200 191 Hydraulic Steam 1,104 1,37 1,230 1,090 1,58 89 1,87 52 1,946 534 1,66 73 95 1,53 89 1,58 865 1,53 1,410 1,07 77 1,62 79 1,68 15, 095 14,185 Total 2 48 2,32 2,48 2,400 2,480 2,400 2,480 2,48 2,400 2,48 2,400 2,48 29,280 191 Hydraulic Steam 804 1,67 72 1,512 80 1,67 87 1,52 2,480 2,400 1,73 74 1,52 95 1,81 58 2,48 2,400 2,48 20,528 8,672 Total 2,48 2,24 2,48 2,400 2,480 2,400 2,48 2,48 2,400 2,48 2,400 2,480 29,200 191 Hydraulic Steam 2,48 2.24C 2,48 2.400 2,480 2,400 2,48 2,48 2,400 2,48 2,400 1,860 62 28,580 620 Total 2,48 2,24 2,48 2,400 2,480 2,400 2,48 2,48 2,40 2,48 2,40 2,48 29,200 191 Hydraulic Steam 2,480 2,06( 18 2,48 2,400 2,480 1,98 41 2,48 '0 2,480 2,400 2,18 29 1,89 506 2,165 31 27,488 1,712 Total 2,48 2 24 2,48 2,400 2,480 2,40 2,48 2,48 2,4( 2,48 2,400 2,480 29,200 191 Hydraulic Steam 2, 05S 4& 1,76 53 1,59 88? 2,40(1 2,480 1,823 57 1,70 780 89 1,59 86 1,54 1,44 1,03 74 1,654 71 1,76 18,471 10,809 Total 2,48 2,32 2,48( 2.40C 2,480 2,4( 2,48 2,48 2,4( 2,48 2.40C 2.48C 29,280 2 40C 92 36C 8,101 1 79 R9S o 1 55 " I 11,339 24Qfl 2 40C 2 48 2,48 19,440 Hydraulic .... Steam l,39 r 1,08, 1,30" 95. 1,52 9b 1,831 56 2,237 143 2,11 28 2,07 40 1,80" 67 1,84 55 1,85 62 1,56 83 1,58 89( 21,300 7,920 Total 2,48 2,251 2,48 2,4