Publication: The Electrical Engineer
New York, NY, United States
THE UTILIZATION OF WATER POWER IN
CALIFORNIA THE FOLSOM-SACRAMENTO
SOME time since, the announcement was made that the contract for the installation of an electric transmission plant between the town of Folsom, Cal., where the Folsom Water Power Co. has developed one of the largest water powers available in California, and the City of Sacramento had been awarded to the General Electric Co. and that work upon this important undertaking was to be expedited.
full description of the installation has not yet been published, but by the courtesy of Mr. Albert Gallatin, the president of the company, some data have been made available which indicate that as a power transmission the scheme is in magnitude second only to the Niagara plant, which in many respects it equals in interest. As a matter of fact work has been so diligently prosecuted on the hydraulic end of the scheme for several years past that this work was practically completed before the awarding of the contract referred to.
It is proposed to dam the American River near Folsom and divert its waters, first for power purposes, and secondly for the general irrigation of the entire surrounding country. The magnitude of this undertaking will be understood by the fact that 5,000 horse power will be shortly available for electric transmission purposes, and about 1,200 horse power for use in the Folsom State prison which is adjacent. In addition to this it is proposed to largely supplement the power capacity of the installation by a series of impounding reservoirs on the line of the river in the mountains. The extent of the possibilities in irrigation are indicated by the fact that 400,000 acres of land can be brought under cultivation by means of the water from the tail races.
The foundation for the dam was laid in 1866 and since then the work has been continuously in progress. It was soon recognized that the scheme would accrue in such a marked degree to the benefit of the community that the State of California became interested in the work, and an agreement was entered into whereby the State received from the Company a conveyance for the site of the prison, and a grant of water power privileges of the canal, at the prison, in consideration of giving the aid of convict labor in the construction of the dam and canals. In 1874 additional concessions of land were received by the State allotting the site for the proposed State Prison, in return for additional grants of convict labor to construct the work. The completion of the Prison was delayed and it was not until 1881-2 that the State commenced to discharge its contract to furnish convict labor. There were further interruptions in consequence of differences of interpretations as to the contract, but in 1888 a new contract, at the suggestion of the late Governor Waterman, was entered into between the State and the Company, providing for a large increase in the magnitude of the dam and canals, for a proportionally more ample water power privilege to the State at the Prison, and for a correspondingly increased contribution of convict labor by the State. Under this expanded contract the work is now rapidly approaching maturity.
To put it broadly, the nature of the contract is as follows : The State is to construct a dam and all the mason work of the dam and canals by State prison labor, and in return is to receive 1200 horse power, to be delivered at the State power-house, situate on the canal about 100 feet below the dam. The canal is forty feet wide at the bottom, fifty feet wide at the top, and eight feet deep, and has a capacity of 84,000 cubic feet of water per minute As shown in Fig. 1, it follows the bank of the river, and has been constructed partly with masonry walls, partly by deep cuts in solid rock, and partly by earth excavation and filling.
Just before reaching the power-house site an immense log basin has been constructed, to hold the logs of the American River Land and Lumber Company, for supplying a large saw mill which will soon be erected at this point. This mill will receive sugar pine timber from the woods of El Dorado County, for which, heretofore, there has been no outlet. It will be operated throughout by electricity, and will be a model of the most modern developments in saw mill construction.
The power house of the Sacramento Electric Power and Light Company is located on the west side of the town of Folsom, just opposite the centime of the business portion of the town, and almost within a stone's throw of the Postoffice. An immense cut in solid rock has been made some sixty feet deep, 100 feet wide, and 150 long. In this cut the massive masonry foundations for the machinery and superstructure of the building have already been laid, and the granite walls, piers and arches are rapidly rising to form a completed building, in which vast quantities of water are to be controlled and their energy transformed into electric power. From the canal, which at the power house has been widened out into a forebay 150 by 100 feet, and ten feet deep, steel inlet pipes eight feet in diameter lead the water to the water wheels. The dam is 650 feet long, 24 feet wide at the top, 87 feet wide on the bottom, and 89 feet high at the highest point. It contains 48,590 cubic yards of granite masonry. The storage bason or reservoir is 3£ miles long and has a holding capacity of 13,000,000 cubic yards of water. The mason work is all of the most solid character, and is laid in Portland cement of which over 20,000 barrels were consumed in the dam headworks. The passage of water into the canals is controlled by massive head-gates on either end of the dam, each head-gate being 25 feet in width. The canal on the west side of the river has yet to be constructed; but the east side canal is completed from the dam to the site of the power house at Folsom about two miles below.
The dam contains two entirely novel features, namely, the method by which the main head-gates are controlled and the method by which the impounding capacity of the dam may be increased at will. The engraving, Fig. 2, shows the hydraulic mechanism controlling the head-gates. These are operated by water power under high pressure which is obtained by means of special hydraulic accumulators, manufactured by the Risdon Iron Works of San Francisco. The second novel feature consists of a shutter made of heavy planking and securely truss braced, which in its normal position rests across the top of the dam along the entire length of its crest. Usually the water flows over this, forming a waterfall; but in periods when a scarcity of water is apprehended the shutter is raised, the overflow is arrested, and the depth of water in the dam is increased by over six feet. The engineering interest attaching to this achievement will be evident when it is remembered that the width of the overflow is 200 feet.
About a thousand feet below the dam the canal passes by and through the State power-house, gates being so arranged that either all the water or only as much as is needed, may go through the State water wheels. In accordance with the admirable provision throughout the whole installation for perfect economy of water, the water here is not lost but continues down the canal, at a slightly reduced head, having fallen 7.3 feet in passing the State power-house, where 1200 horse power can be developed by this loss in head. The canal is divided into three sections, and is about two miles in length, the power-house being situated at the extreme end where a fall of 55 feet will be available. The power-house is of stone, two stories high, the water wheels and generators being located on the lower floor, twenty feet above the level of the tail race.
The hydraulic plant consists of four pair of McCormick turbines of a capacity of 1200 H. P. each, direct connected to electric generators of corresponding capacity, which run under a head of 55 feet at 350 revolutions per minute. There are also two exciter wheels direct connected in a similar manner. These wheels are manufactured by the S. Morgan Smith Works, of York, Pa., under contract with the Pelton Water Wheel Co., of San Francisco, and are of larger capacity than any so far constructed in this country with the exception of the Niagara plant. As they embrace many new features covering the most advanced practice in electric and hydraulic engineering, their operation will attract much attention.
The water will be discharged through tunnels under the power-house into open cuts to the river, or may be again taken up and led into irrigation canals for supplying irrigating water to a vast section of the country south and east of Folsom. The power station will be divided into two parts by a water-tight masonry wall, thus separating the waterwheel plant, with its pipes, gates, etc., from the electric generators, switchboards, transformers, etc., of the dynamo room. In the dynamo room there will be four three-phase alternating current generators of the General Electric Co.'s type, each capable of developing 1,000 horsepower, the shafts of which will be coupled direct to the shafts of the four water-wheels. These generators have been under construction at the works of the General Electric Company at Schenectady, N. Y., for the past four months. They weigh 40 tons each, and are the largest in the world except those being built for the Niagara Falls power plant. The current developed by these dynamos will be passed through step-up transformers, and after being raised to 10,000 volts, it will pass to the transmission line.
All possible delay or shut-down for repairs or renewals will be guarded against by the erection of a double-pole line all the way from Folsom to Sacramento, a total distance of about 24 miles. About 2,600 poles will be required for these lines. They will be of red cedar, 40 feet long, 16 inches in diameter at the butt and when erected they will constitute a pole line of exceptionally enduring character. Each pole line will be fitted with two cross arms, containing 6 bare hard-drawn No. 0 copper wires supported on double petticoat porcelain insulators, constituting two circuits, each 3-wire circuit corresponding to one dynamo, at the power-house, and capable of transmitting 1,000 horse-power to Sacramento.
When it is realized that each wire is only one-fourth of an inch in diameter, and that three of them will transmit 1,000 horse-power 23 miles, some idea of the flexibility of electrical energy can be obtained.
The transmission line will follow the county road from Folsom to M and Thirty-first streets, thence north on Thirty-first street to the alley between D and E streets, thence east in the alley to Sixth street, thence by the alley between Front and Second streets to Y street — twentyfour and one-half miles.
The power is all brought into a sub-station, passed through step-down transformers, which reduce the voltage from 10,000 volts to about 100 volts, when it is ready for distribution for incandescent and arc lighting, operating the entire street railway system, running motors, heating, cooking, and all the multifarious uses to which electricity is now being put.
In the sub-station, which will be an imposing fire-proof brick structure of two stories, will also be located all the regulating and controlling devices with which to operate the distributing system.
It is safe to say that the future of the electrical power transmission of California depends very largely on the outcome of this remarkable installation, and the progress of the work of construction is being eagerly watched, particularly by mining interests.