THE NEAR COMPLETION OF THE LOS ANGELES AQUEDUCT
In the issue of FIRE AND WATER ENGINEERING of September 2, 1908, the first description of work on the Los Angeles new waterworks system was published, in which data concerning its construction up to that time was given. This second special contribution of the great work will prove interesting as showing the completion of one of the important engineering projects of the country and the modern methods employed in building this long and expensive aqueduct. The construction of the Los Angeles aqueduct now nears completion. The enterprise has excited international attention, because of its magnitude and by reason of the unusual difficulties of construction. With the exception of one comparatively small contract, all the work has been done by the municipality itself. It is a public work which will be completed in advance of the time for which it was promised and at a cost well within the original estimate. It will prove of great economic value in providing an ample supply of water for irrigation and domestic use and the development of hydroelectric power.
The city of Los Angeles, a municipality of 400,000 population in 1904, was confronted by a diminishing water supply, at present obtained from the surface and subterranean flow of a stream called the Los Angeles river. No municipality has greater need for an abundant water supply, as it is situated in a semi-arid region where the average precipitation does not exceed 15.67 inches annually, and no rain falls from April to the last of October. The per capita consumption of Los Angeles is 14u gallons daily, while the daily per capita consumption of London amounts to only 28 gallons. After Federal and Los Angeles engineers had investigated the conditions for a period extending over several years, the nearest adequate source of supplementary supply was found to lie in the Owens river, a stream draining the eastern face of the Sierra Nevada Range, which forms the roof-shed of the United States. To this source the city has gone. Purchasing 120 square miles of territory in the Owens Valley and with the active co-operation of the United States government in the way of public lands and helpful legislation. Los Angeles has undertaken to carry a daily supply of 280,000,000 gallons from this source into the Fernando Valley, at the mouth of which the city is situated. To accomplish its purpose the city is constructing a concrete aqueduct across the great Mojave Desert and under the Coast range (Sierra Madre) of moutains. The aqueduct is reinforced by an extensive system of storage and regulating reservoirs. The length of the aqueduct from the intake to the impounding reservoir at the outlet is 240 miles. From the latter point the water will be distributed for irrigation or carried 10 miles further through steel force mains to be connected with the city’s present waterworks. The system is gravity throughout. The intake is 3,812 feet above sea level; the outlet of the lowest reservoir is at an elevation of 1,020 and the elevation of the Los Angeles City Hall is 276 feet above sea level. The total estimated cost of the aqueduct proper, exclusive of other features yet to be discussed, is $24,500,000. This in a word is the Los Angeles aqueduct, or as it is quite popularly known, the Owens river project. The economic value of the aqueduct lies in the fact that it will provide domestic water for 1,000,000 people; through a municipal irrigation system irrigate 135.000 acres of land surrounding the city, and from its 1,500 feet of fall develop a maximum of 120,000 horsepower of electrical energy, for which funds have already been partially provided. The foregoing briefly explains the impelling motives of tile city in undertaking a work of such magnitude and the ultimate possibilities of the project. It is similar to tile Panama Canal in that it is without a parallel in history. It must be remembered that Los Angeles to accomplish its purpose went into a naked desert and among high and desolate mountains— a country practically without habitation, fuel or water. The work of preparation in point of the spectacular outrivals the actual construction. Only tile bare outlines can lie given here but the preparatory features included the construction of a standard guage steam railroad 142 miles in length by the Southern Pacific Railroad Corporation which procured thereby the hauling of the 20,000,000 ton miles of freight; the building of 315 miles of mountain roads and trails costing $260,000; the installation of three waterworks systems comprising four reservoirs and 150 miles of mains at a cost of $250,000; the building of a municipal copper line telephone system with 460 miles of lines and costing $75,000; the erection of three hydro-electric power houses and 268 miles of high tension transmission line to furnish motive energy and light along the aqueduct zone at a cost of $450,000; the construction of a large number of structures of all classes and descriptions for men, animals and machinery; and, finally, the purchase of clay and limestone deposits and the erection of a municipal Portland cement mill with two auxiliary tufa grinding mills at a cost of $800,000. A little over $4,000,000 was expended before the work of aqueduct excavation was even started. Since June of 1909, the excavation lias continued at a rate exceeding 50 miles per year. Today the excavation totals 184 miles, of which there is 21 miles of open canal and 163 miles of completed concrete ditch and conduit ready for the water. It is confidently expected that the aqueduct will be ready for the water by January or February of next year. A tabulation showing the classification of the work, together with the completed and uncompleted quantities is as follows:
The original design of the aqueduct, if the power was not developed, called for the use of the natural bed of the Sail Francisquito canon for a distance of about 12 miles. Owing to the large asset in the power feature, hydro-electric power is to be developed simultaneously with the completion of the aqueduct, so that instead of being allowed to follow the stream channel, the water will he carried along the rim of the canon with the following classification, exclusive of about 2 miles of penstock:
Work on this power section of the aqueduct was begun in August of last year, and on April 1. 20,000 feet of the tunnel work had been excavated. The system of reservoirs which is now under construction is one of the largest in existence. The Round Valley reservoir with an impounding capacity of 340,890 acre feet and which will be situated 50 miles above the intake, will not be constructed until after the aqueduct is in operation. It has been designed solely for the storage of heavy years of precipitation as a safeguard against years of drouth. The other reservoirs of the system are under construction and are as follows: Haiwee, 03,800 acre feet; Fairmont, 7,020 acre feet; Dry Canon, 1,325 acre feet; Fernando (lower), 25,000 acre feet. Of the foregoing the Dry Canon reservoir is completed, the Haiwee and the Fairmont are half completed and the Fernando is well under construction. The dam of the Low er Fernando will be 700 feet wide at the base, 7,320 feet in length. 130 feet in height and the fill amounts to 2,700,000 cubic yards. It is being built by sluicing, and exclusive of the Gatun dam of the Panama Canal, will be the largest hydraulic filled dam in existence. This reservoir is at the terminus of the aqueduct, and is calculated to afford four months’ supply for 1,000,000 population. Two other large reservoir sites have been surveyed as a part of the general plan of irrigation, but no work has as yet been undertaken on their construction. The most important phase of the work, in fact one of the controlling factors in the completion of the aqueduct was the Elizabeth tunnel. This tunnel was “holed” March 1, 1911, nearly a year in ad vance of the estimated time required for its excavation. This tunnel, the second longest water tunnel in the United States, was driven 26,870 feet through the hard gneiss rock of the Sierra Madre range in the short space of 1,240 working days. The average rate of progress from each portal was approximately 12.36 feet per day. United States tunnel records were repeatedly broken, that of 449 lineal feet in a thirty-day month from a single heading being advanced to 604 feet for the same interval. The work was carried on continuously in three eight-hour shifts from opposite sides of the range, the excavation being accomplished with Leyner drills driven by compressed air, and the muck handled by electric motor railways. Throughout the task, the work excepting at the very start, when crude methods were adopted until the arrival of proper machinery, the most modern electrical equipment was used. The underground and surface forces at each portal averaged 100 men throughout the drilling. F’rom the north portal the progress was made exceedingly difficult by water pockets and swelling earth and heavy timbering was required. F’rom the north portal, 13.500 feet were driven, and from the south portal 13,370 feet. The center lines of the tunnel met within 1⅛ inches, and the grades checked to five-eighths inch. The estimated cost for the completed tunnel was $75 per lineal foot, or $2,015,250. The actual cost of boring and concreting has been $50.69 per foot, or a total of $1,362,040, which is $653,210 below the amount set aside for the purpose. Concreting is now nearing completion. Including the construction of the Elizabeth tunnel, the tunnel work ot the aqueduct until the first of this year has progressed at an average rate of one mile of tunnel excavation per month. The mechanical cxcavating equipment for conduit and canal excavation consists of two powerful electric dredges which have now completed their work in the Owens valley. 13 steam and electric power shovels and one giant excavator. The labor force has ranged from 2,500 to 4.300 men, during the summer season, it being difficult to obtain laborers who were willing to go out on the desert. The hospital department, as well as the commissary, were let by contract, the city receiving no financial return and having the privilege of terminating the contracts upon 30 days’ notice if the city’s standard of board, medical and sanitary care of men and camps is lowered. The men pay $1 per month for medical attendance, and board is furnished at the rate of 30 cents per meal. Rates of pay for day labor have ranged from $2 to $2.75 for eight hours’ work, depending upon the labor market as well as the character of the labor. Miners and mechanics have received from $3.50 to $3.75 for eight hours shift, and foremen $3.50 to $4.50 per day. With the exception of one small contract representing 3 per cent, in point of distance, and which was in easy construction, all the work has been done directly by city forces from engineers down to day laborers. On this work also, the city of Los Angeles for the first time in American municipal history, inaugurated the bonus system of payment. Its success surpassed the most sanguine expectations of the city’s engineers. Whether it is in conduit excavation, concrete lining tunnel, boring, siphon building or other work, the chief engineer sets as a basis of bonus payment, dependent upon the classification of the particular piece of work, and the average progress that should be made by the crew or gang in a ten-day period. For all in excess of this amount, each man participating in the work, in addition to his daily wage, is paid n established sum proportionate to the progress made. On the Elizabeth tunnel for example, miners were accustomed to receive monthly pay checks which, with their bonus ranged from $140 to $170, and muckers and other laborers’ checks were in proportion. This system has brought out the best that was in every man, because in the hope of reward there has been an incentive for him to do his best. Moreover, it created a rivalry between each of the 50 camps and brought an organization of unusually high efficiency. As drones retarded the work, delayed progress and so cut down the bonus payment, the workers of their own accord drove out the drones. The working out and development of the system has excited a great amount of interest from engineering publications, engineers and municipal officials throughout the United States. Another phase of unusual municipal activity in connection with this enterprise has been the building and operation of cement mills and the introduction and use of tufa cement. In this phase of the undertaking, $875,000 of the public funds were expended. The Portland cement mill was erected at Monolith, close to the line of the aqueduct, about equidistant from the intake and outlet adjacent to large deposits of limestone and clay and with transportation facilities that have reduced freight rates to a minimum. This mill was first fired in March, 1909, and with a capacity of 1,000 barrels per day, to January 1. 1912, had ground 575.000 barrels. It was found that at Monolith and two other points in close proximity to the aqueduct line there were large deposits of tufa strikingly similar to the Italian tufas used in the construction of the Coliseum and the Roman aqueducts. Tufa is a volcanic ash metamorphosed by volcanic heat and water into a white, brittle, rock. A of tests and experiraents demonstrated that an excellent cement could be manufactured by taking equal amounts by volume of Portland cement and ground tufa and regrinding them to a fineness of not less than 90 per cent, passing a 200 mesh screen. The seven day test shows to the advantage of the Portland, but alter that the tufa cement surpasses the Portland in breaking strength, and at the end of one year, exceeds Portland by about 20 per cent. In 1909-10, therefore, tufa grinding mills with an aggregate daily capacity of 2,000 barrels, were erected on the sites of the deposits. The advantages of this municipal move will be seen in a comparison of cement prices. At the time aqueduct work was started, commercial cement sold in the Los Angeles market at $2.25 per barrel. The city has been able to manufacture her own Portland cement at a cost of approximately $1.30 per barrel, and the tufa cement at from 83 cents to 80 cents per barrel, besides reducing freight charges fully 50 per cent, byhaving two of the tufa mills directly on the aqueduct where the material was to be used. Now that the aqueduct is nearing completion, the tufa mill machinery will probably be disposed of to the Federal government while it is possible that the Portland mill may be retained to furnish cement tor other large public works now under way. At the time this is being written, the most interesting phase of construction is the fabrication of the inverted steel siphons by which the waters of the aqueduct are to be carried across canons and valleys. So far as the writer knows, these huge steel pipes are the largest and longest in existence. They range in length from Gil 15,596 feet, and in diameter from 8 feet 6 inches to 11 feet. The thickness of the steel varies from one-fourth inch to 1 1/8 inches. The aggregate length is 49,576 feet, the cost of which installed represents an expenditure of $1,400,000. The total tonnage amounts to 14,500 tons. These siphons will be under heads ranging from 75 to 450 feet. The siphons are all of single plate construction. The material is furnished under contract and the work of erection is performed by the city. No foundry on the Pacific coast was equal to the magnitude of the task. ‘The plates are therefore rolled, punched and bevel-sheared under the eyes of Los Angeles inspectors in the steel foundries of Pittsburgh, Pa, and Camden, N. J. There they are erected section by section, given a number on a diagram showing the exact location of every plate and rivet hole in the completed structure, are then taken apart, nested on flat cars and dispatched to the railroad station nearest the point of their destination on the Mojave desert. From here they arc freighted by 12-mule team wagons from 5 to a maximum of 30 miles to the point of erection where the diagrams have already preceded them. Here they are lifted by aerial trams to their place along the canon wall and are riveted into place; 24-inch double disc gate valves are placed at the lowest points of the siphons first for cleaning purposes and secondly to divert the flow of the aqueduct into natural water channels should a break occur in the conduit high along the mountain side to the south of them. This work is proceeding simultaneously at seven different points, and should be completed during the late fall. Where the head is low, concrete siphons are used in place of steel on account of the cheaper cost. These pipes, used also in the approaches to the steel siphons are 10 feet in diameter, strongly reinforced with steel and constructed of very rich cement. The illustration shows the manner of reinforcing. For the partial development of the hydro-electric power, the city voted $3,500,000 in the spring of 1910. While the aqueduct is being built primarily for a domestic water supply, this feature in point of revenue is by far the most important. The board of electrical engineers reported in 1910 that a maximum of 90.000 kilowatts, or 120,000-horsepower, can be generated from the aqueduct with all conditions present for reliability of service and favorable low costs of operation. Owing to the regular and assured flow through the aqueduct, they reported that in their opinion, no reserve steam plants are necessary, and that from this and other favorable conditions, one of which is that the major part of the electric energy can be developed in close proximity to the city, the cost delivered at the Los Angeles city limits will not exceed $60 per horsepower. This is much less than the cost at which hydraulic power is at present developed on the Pacific coast.
The plans call ultimately for the operation of seven power houses, two of which, Division Creek and Cottonwood, are now in service as construction plants.
These plants are as follows:
Plans for the partial development of power house No. 1 in San Francisquito canon are now ready for the construction department. Contracts have been let to the Union Iron Works and the Westinghouse Company for machinery to cost $300,000, with delivery to be completed by August 1, when the buildings will he ready to receive it. This plant will have a capacity of 37,500-horsepower, and is scheduled to be complete and ready for operation in January of 1913. Other units of power will be installed as a market for the product developed.
Whether the power will he disposed of to the Los Angeles power companies at an aggregate of $5,500,000, or a distribution system built by the municipality, remains to he voted upon by the people whose attitude at the present time is strongly in favor of the latter alternative. Irrigation, the last subject to be discussed, is second only to power development from a financial standpoint. It must be kept firmly in mind that Los Angeles lies within a semi-arid region where land values are directly proportionate to the accessibility of water for irrigation. This is shown by the fact that lands which will be watered by the aqueduct, as dry land sold from $20 to $50 per acre seven years ago, to-day are being sold from $350 to $500 per acre. Approximately 225,000 acres of land for which little water is now available, lie within a radius of 30 miles of the municipality. The surplus waters of the aqueduct will supply irrigation for 135,000 acres of this amount, allowing for the return of 2,000 miners’ inches by seepage into the city’s present infiltration galleries provided the Fernando valley is given irrigation. Studies by the Los Angeles water department show that it requires the same amount of water to irrigate an acre of citrus trees that is required for an acre given up to urban population. The city in its remarkable growth is constantly encroaching on urban lands. The very nice problem enters of applying the water for irrigation in the localities which will gradually and insensibly grow from suburban into urban territory, with the accompanying gradual transfer of the water from irrigation to domestic use. For the past year a corps of engineers have been working on this problem. The irrigation system will, therefore, probably differ from the concrete canal systems found in California in that it will consist of large steel pressure mains ranging from 4 to 6 feet in diameter, leading off from the San Fernando Reservoir to water the country below it. Probably the plan adopted by the United States Reclamation Service of forming irrigation districts, will be put in force. In this event the districts will probably be required to defray the cost of all the work which will be installed by city engineers, and become the property of the city. The actual cost to the irrigators has not been fixed, but the average annual rental for water in southern California is approximately $10 per acre. With all the available water power developed and with the surplus water disposed of for irrigation, J. B. Lippincott, assistant chief engineer of the aqueduct, has computed that for a total expenditure of $31,500,000, Los Angeles will receive a net annual income of $4,425,000, which is the equivalent of 5 per cent, interest on $88,500,000. In conclusion, this project now on the eve of completion, must be considered a foremost municipal engineering achievement in its large conception, its building by city forces and its promise of large economic returns.