The Hetch-Hetchy Water Supply for San Francisco

The Hetch-Hetchy Water Supply for San Francisco

System Fully Explained and Illustrated by Maps by City Engineer—History of the Project — Engineering Features —Work Well Under Way—Great Benefits to be Derived

City Engineer

M. M. O'Shaughnesay, City Engineer, San Francisco

THERE have been so many misstatements and so much misconception as to the scope of the Hetch-Hetchy water supply project for the city and county of San Francisco, and as to the present condition of the work and what has so far been accomplished, that it was decided by FIRE AND WATER ENGINEERING to write to M. M. O’Shaughnessy, city engineer of San Francisco, and obtain from him an authoritative statement on this subject. The following letter and enclosures are self-explanatory and set at rest the many wild statements and surmises that have appeared from time to time in the local press about the projects :

To the Editor: Your letter of March 15, enclosing article from the San Francisco Chronicle of the 26th of February has been received. I am enclosing you two documents, which will give you the status of our Hetch-Hetchy project. We have spent $8,000,000 to date and have contracted for a dam that will cost $5,500,000 and which will store 200,000 acre-feet of water, or over 60 billion gallons. This work will be done in about two years. We are building 18 miles of aqueduct and going to let a contract on the 21st of April for about 16 miles of the 18, at a cost of six or seven million dollars. At the end of this aqueduct we shall have a power drop which will give us over 50,000 hydro-electric horse-power, which we propose to sell at $50 per horse-power per year, or a revenue from our mountain development of very nearly $2,500,000, which will pay interest on that part of the work. The tail race 140 miles distant from San Francisco. Water will be delivered by gravity at an elevation of 250 feet in San Francisco. It is also the intention of the city to purchase the existing private water company, the Spring Valley Water Company, and an election will be called for that purpose inside of the next four months. With the enclosed documents, I trust this will give you the information you need. M. M. O’SHAUGHNESSY,

City and County of San Francisco, City Engineer.

March 24, 1920.

The Hetch-Hetchy Project in a Nutshell

The Hetch-Hetchy project is a plan for a municipal water supply, evolved by the City and County of San Francisco, after a thorough and comprehensive study of all possible sources, for the collection and storage of waters of the Tuolumne River and its tributaries near their sources in the Sierra Nevada Mountains, and the transmission of those waters across the San Joaquin Valley and through the Coast Range of mountains for delivery to the City of San Francisco and its environs; due advantage being taken of appropriate drops in the conduit routes for the generation of the maximum quantity of hydro-electric power which can thereby be economically developed.

History

The project had its beginnings back in 1901, when James D. Phelan, then Mayor of the City, now United States Senator from California, filed water locations on the Tuolumne River and its tributaries, the Cherry River and Eleanor Creek. These appropriations were kept alive by preliminary development work until a permit could be obtained from the Federal Government for the acquisition of storage reservoir sites situated on public lands within the limits of the Yosemite National Park (not Yosemite Valley). This permit was granted by Secretary of the Interior Garfield in 1908 to lands and waters tributary to the Tuolumne River in the northern part of the Park and twenty miles distant from the Yosemite Valley proper, which is drained by the Merced River. Having acquired this permit, San Francisco proceeded to acquire, at an expense of $1,915,000, all privately owned lands in the Hetch-Hetchy Valley and the rights and holdings on the Tuolumne and Cherry Rivers and on Eleanor Creek, a tributary of the Cherry, rising at the outlet of Lake Eleanor. A movement was started by certain coteries of so-called “nature-lovers” and others to revoke that portion of the Garfield permit relating to the Hetch-Hetchy Valley. President Taft ordered an investigation and report by a Board of United States Army Engineers. This board examined all alternative sources of supply which had been suggested. The report, under date of February 19, 1913, recommended the use of the Hetch-Hetchy Valley and the Tuolumne supply as being the cheapest and most economical for the City’s use and affording the greatest hydro-electric development possibilities. Previous to the report, the city had an exhaustive examination of all available sources made by John R. Freeman, engineer, associated with the water supplies of Boston and New York. He strongly recommended the Tuolumne source as the best and outlined the scheme of development which, with some necessary modifications, is now being followed. After taking testimony and examining all reports submitted, Secretary Fisher gave it as his opinion that Congress alone had the power to grant the privileges sought by the city. After a great deal of argument before Congress, the “Raker Bill’ was passed by both Houses and signed by the President on December 19, 1913. This act was framed on the recommendation of Secretary Lane of the Interior Department and Secretary Houston of the Department of Agriculture, and by it Congress (Stats. 1913, p. 242) vested forever the city’s rights in 420,000 acres of the public domain. The water locations have from their inception been carefully protected and title to the same is fully vested in San Francisco under the provisions of the Civil Code of California. Antecedent to this, on January 4, 1910, the people of San Francisco, by a vote of 32,886 for and” 1,609 against, authorized the issuance of $45,000,000 in bonds for the construction of the project.

Actual work was commenced as soon as the Congressional grant was obtained. Surveys were completed, many miles of wagon road were built, a broad-gauge railroad sixty-eight miles long was located and built, the floor of Hetch-Hetchy Valley was cleared of timber, a sawmill was constructed and put in operation, diamond drill borings at the main dam site and along the line of the tunnel aqueduct were made, a construction power plant was built, with a dam at Lake Eleanor to store eight billion gallons to carry the plant through the dry season, and an aqueduct to supply the plant with water, electric transmission lines connect it with all working points on the tunnel aqueduct, camps, warehouses, headquarters buildings were constructed, and work was finally begun on the Hetch Hetchy dam foundations and diversions tunnel and at all tunnel portals and shafts on the Mountain Division of the aqueduct.

During the period of the war the City carried on work with a force of from 400 to 500 men, with due care always not to interfere with the selective draft or the nation’s need for materials and equipment. Progress was necessarily not so rapid as would otherwise have been the case, but it has sufficed to place the project in a position where the maximum force of men can now be ad-

vantageously employed to hurry the undertaking to completion. Sound economic reasoning dictates that the Mountain or power-generating division of the project be completed first, in order that the burden upon San Francisco’s taxpayers of paying interest during construction may be reduced through receipts from power sales at the earliest possible moment. The dominant purpose of the project is, however, water supply, and every effort must be made to complete the water conduits without unnecessary delay in order to remedy the water shortage from which the San Francisco Bay cities have long been suffering.

Outline of the Principal Engineering Features

The space afforded in this resume suffices for only a brief description of the principal engineering features of the project. For convenience the work has been divided into ten divisions, to be known as the Lake Eleanor Hetch-Hetchy, Mountain, Priest, Moccasin, Foothill, San Joaquin, Coast Range, Bay Crossing and Peninsula Divisions. Outside of surveys, geogical and engineering studies so far conducted over the entire work, the construction accomplished to date has been entirely on the Lake Eleanor, Hetch-Hetchy and Mountain Divisions. The following structures have been completed or are under construction:

Hetch Hetchy Railroad

The Hetch-Hetchy Railroad, sixty-eight miles in length, extends eastward into the Sierras from HetchHetchy Junction. The elevation of Hetch-Hetchy Junction is 935 feet, from which the railroad, after crossing two low ridges, drops to 625 feet in a distance of nine miles to cross the Tuolumne River, some twelve feet above extreme high water. From the Tuolumne River the road extends to Jacksonville, thence up Moccasin Creek and Grizzly Gulch to Priest, and thence to Big Oak Flat and Groveland. Most of the climb for eastward traffic toward the dam is on a grade from three to four per cent.

Lake Eleanor Dam

To insure a sufficient water supply for operating Early Intake Powerhouse through the dry season, and to secure its water rights under the laws of the State of California, a concrete dam has been erected by the City across a gorge one mile below Lake Eleanor, and raises the surface of the lake thirty-five feet, to 4,660 feet above the sea.

This structure is 1,260 feet in length, 70 feet in maximum height, and contains 11,000 cubic yards of concrete, heavily reinforced. The dam is of the buttressed arch type, but with several original features for additional safety, developed by the city engineer’s studies. It has twenty arches, each with a span of forty feet. The arches are on an incline of 50° and are supported by buttresses, heavily reinforced. It is curved in plan and located at the site of and will form a part of a future larger dam. An interesting feature is that the cross-section of the arches is circular on a horizontal plane and elliptical on a normal plane.

Early Intake Construction Power Plant, Aqueduct and Transmission Line

The temporary power plant is located on the Tuolumne River at Early Intake, about ten miles distant from Lake Eleanor. The available head is approximately 345.5 feet. The water for power purposes is diverted from the natural flow of Cherry River, augumented when necessary by water released from Lake Eleanor, and is then led through a conduit of 130 million gallons daily capacity and 3.3 miles long, consisting of 1.2 miles of open ditch, 1.1 miles of flume and one mile of tunnel. The forebay at the head of the pipe line consists of an enlarged section of the flume and affords a limited capacity for regulating purposes. Owing to the steep hillsides, it was impractical to create a forebay reservoir. From this forebay the water is carried to the powerhouse in a forty-two inch riveted steel pipe 530 feet in length. Some idea of the character of the country will be gained by realizing that this pipe line drops 320 feet in 530 feet, equivalent to seventy-five per cent grade. The power equipment installed in the powerhouse consists of three turbines of the Francis Pelton type, designed to operate at 720 revolutions per minute and to develop 1,500 horsepower each. Each of these water wheels is direct connected to a 2,300-volt, three-phase, sixty-cycle generator of 1,000 kilowatts capacity, with a direct-connected exciter operating at 125 volts.

Hetch-Hetchy Dam and Reservoir

At its lower end, Hetch-Hetchy Valley narrows to a gorge about sixty feet wide at ordinary low water level (elevation 3,500 feet), and 900 feet wide at the elevation of the crest of the proposed ultimate dam (elevation 3,812 feet). The underlying bedrock has been very carefully studied by means of diamond drill borings. It will be necessary to excavate to an average depth of seventyfive feet below the river bed in loose gravel, sand and boulders to obtain an excellent bedrock foundation. The dam is to be of the arched gravity type and built of cyclopean concrete. The dam will be built in two installments. Work is in progress on the construction of the first installment. The estimated cost of construction at the contract prices is $5,447,792.50.

The present contract includes the complete foundation below stream level for the ultimate dam. At its base, this foundation will have a thickness (up and down stream) of over 300 feet. The total height of the dam above the foundations will eventually be nearly 400 feet, making it higher than any dam now existing in the world. The crest length will be about 900 feet, and the thickness at the crest 25 feet. As in the lower dam, the crest will be utilized as a roadway. The spillway will be a channel around the top of the dam, with the spillway lip at elevation 3,800. The siphon spillway will, of course, be closed permanently on completion of the dam to its ultimate height. The initial dam will contain about 370,000 cubic yards of concrete, and the ultimate dam about 625,000 cubic yards.

The reservoir created by the initial dam will have a capacity of 66,000,000,000 gallons, or 202,000 acre-feet, and on raising to the ultimate height the capacity will become 112,000,000,000 gallons, or 343,000 acre-feet. The floor of Hetch-Hetchy Valley has been cleared of timber, in order to protect the impounded waters from contamination due to the decay of submerged timber. A diversion tunnel twenty-four feet in diameter and 900 feet long has been driven through the rock promontory on the south side of the damsite. The waters of the Tuolumne River will be turned through this tunnel during the construction of the dam, and afterwards the tunnel will be utilized for the release of water from the reservoir. For the latter purpose there will also be a number of channels through the body of the dam, with an elaborate system of valves.

HETCH HETCHY WATER PROJECT MOUNTAIN DIVISION Topographical Map, Mountain Division, Hetch-Hetchy Water Project

Mountain Aqueduct Twenty Miles Long

From Hetch-Hetchy reservoir to Early Intake, a distance of twelve miles, the river bed of the Tuolumne will serve as a conduit for the waters released from the Hetch-Hetchy reservoir, until such time as the necessity for the generation of additional power will justify the construction of a tunnel from Hetch-Hetchy dam site to the forebay above Early Intake. From Early Intake the first section of the tunnel aqueduct extends to the South Fork of the Tuolumne, a distance of four and onehalf miles. This tunnel can be worked from the two portals only, since the height of the mountain penetrated by the bore is too great to permit of any shafts being sunk to the tunnel line at intermediate points. Work is now in progress at both portals. The rock encountered is extremely hard. The present rate of progress is about seven feet daily from each portal, but this can be more than doubled, so that the tunnel can be completed in less than three years.

The time of completion of this tunnel is the controlling factor in the time necessary to supply San Francisco with 66,000 horsepower of electrical energy, as the remaining 13 1/2 miles of tunnel between South Fork and the regulating reservoir above Moccasin Creek Powerhouse can be worked from two portals, two intermediate shafts and seven adits.

Forces Engaged on Construction Work

The work now being carried on in the field by the city’s forces comprises the excavation of the aqueduct tunnels above described and the operation and maintenance of the Hetch-Hetchy Railroad, the construction power system and the sawmill. The force engaged on all of this work averages about 500 men. The contractor constructing the Hetch-Hetchy dam is employing on his preliminary work 300 men, making a total of about 800 men working on the project.

Future Stages of Project Construction

Another tunnel 5.75 miles in length will extend from Moccasin Creek to Red Mountain Bar, where the Main Tuolumne River will be crossed with a short steel pipe. Thence a tunnel 11.3 miles in length will lead to Oakdale Portal, on the easterly side of the San Joaquin Valley.

From Oakdale Portal (about four miles southeasterly from the town of Knights Ferry), the commencement of the present survey, to Tesla Portal on the west side of the San Joaquin River (about eight miles southerly from Tracy), the aqueduct will consist of 45.2 miles of steel pressure pipes. The aqueduct will be carried across the San Joaquin Valley in pressure pipe, which will pass under the San Joaquin River as a submerged pipe line, and the lower areas adjacent to the San Joaquin, subject to overflow during the annual floods, will probably be traversed by means of pipe lines on substantial reinforced concrete trestles. Through the Coast Range from Tesla Portal to Irvington Gate House, except for a small steel siphon crossing the Alameda Creek channel, the aqueduct will consist of tunnels aggregating approximately thirty-one miles in length. From Irvington Gate House westerly, the aqueduct will again consist of steel pressure pipe 19.1 miles in length, following practically a straight line from the Gate House to Dumbarton Straits, where the Bay crossing will be made by means of pipes placed either in the Bay bottom or in a subsurface concrete tube.

The line thence parallels the Southern Pacific Railroad, through the southerly portion of Redwood City to what is known as the Redwood Portal, two miles westerly from the town of Redwood. From here the aqueduct will consist of tunnels, extending about one and one-half miles westward from the Redwood Portal to the main ridge between San Francisco Bay and Crystal Springs and San Andreas Lakes of the Spring Valley Water Company. From this point the tunnels will follow beneath this main ridge to a point about one mile southwesterly from Baden Station. Here again the construction will be a short steel siphon, across the low area lying between the main Coast Range and San Bruno Mountain, to the San Bruno tunnel portal, crossing the southeast corner of Holy Cross Cemetery and about 500 feet east of the Boulevard. From the San Bruno portal to a city reservoir will be in tunnel. The city has already acquired a large part of the site for the large terminal reservoir, known as the Amazon reservoir. It is located adjacent to the Crocker-Amazon tract, in the southerly part of the city, at an elevation of 240 feet, and will be designed to hold 300,000,000 gallons of water.

Legal Status of Hetch-Hetchy Project

It may be observed from a reading of the history of the efforts made by the City of San Francisco to secure its Tuolumne water supply that nothing has been left undone to protect the security of the City’s water rights from a legal standpoint. Not only do its water locations antedate practically all others on the Tuolumne River, but they have been kept valid by development work continuously performed, by the authorization of construction bonds as provided in Section 1416, Civil Code of California, and by the diligent prosecution of the City’s applications for rights of way before the Interior Department and before Congress as prescribed in Section 1422, Civil Code.

In paragraph (B), Section 9, of the Hetch-Hetchy Grant from Congress the Irrigation Districts are restricted to the present Turlock and Modesto Districts of

250,000 acres, and their enlargement in the future to 300,000 acres. In paragraph 34, U. S. Army Engineers’ report, Washington, February 19, 1913, opinion is rendered that there is adequate water for San Francisco, 400 million gallons daily and for 400,000 acres irrigated with

750,000 acre-feet storage. With a restriction to 300,000 acres in the Congressional Bill, San Francisco’s portion is assured.

Right of Way

The Hetch-Hetchy Grant from Congress and the various departmental approvals which have been given from time to time under its provisions as to right of way locations, fully validate the City’s title in perpetuity to rights of way over the public domain. Certain conditions were indeed inserted in the Congressional grant relative to the protection of the beauties of the Yosemite National Park, the rights of the irrigationists in the San Joaquin Valley, and the guaranty of adequate speed in hydro-electric power development on the aqueduct line. All of these conditions have been accepted by the City and the pro(Continued on page 1318)

Hetch-Hetchy San Francisco Water Supply

(Continued prom page 1277)

ject has been so designed as to give them full effect. Rights of way over privately owned lands have been fully acquired in the Mountain Division and will be purchased over other divisions as fast as funds become available.

Bond Issue

The validity of proceedings relating to the authorization, issuance and sale of the Water Bonds, issue of 1910, from the proceeds of which the project is being constructed, is confirmed by an opinion from Honorable John C. Thomson, bond lawyer of New York City, who is the City’s legal adviser in all bond matters, and an authority of national reputation.

Financial Status of Project

The Hetch-Hetchy project is being financed through the sale of water bonds, issue of 1910. The total authorized present issue is $45,000,000 of 41/2 per cent, bonds, of the par value of $1,000 each. Maturities range from 1922 to 1964. Of this authorization a total of $13,845,000 had been issued and sold on January 21, 1920, leaving $31,155,000 for sale at the Treasurer’s office.

The city of Worcester, Mass., will probably enter into a contract to supply the town of Auburn with water. Water Commissioner George W. Batchelder states that Worcester can easily spare the 400,000 gallons needed daily, as that amount is too small to interfere with the city’s reserve supply.

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