Publication: Western Electrician
Chicago, IL, United States
Snoqualmie Falls Transmission.
In the middle of March the Snoqualmie Falls Power company began the work of building a plant at Snoqualmie Falls to utilize and transmit the power of the cataract to the cities of Seattle and Tacoma, Wash. At that time the Western Electrician gave a brief preliminary account of the project and a picture of the falls. Now the work is well under way, several important contracts have been let, and this journal is enabled to give further details, with pictures showing the work accomplished, of a plant which will embody several features of exceptional interest.
Snoqualmie Falls is an unbroken cataract of 268 feet in the Snoqualmie River, 22 miles east of Seattle, in an air line. Its importance as a possible source of power for use in the adjacent cities has long been realized, and the project of utilizing the power is not a new one. It was not until this year, however, that the necessary financial arrangements were finally completed and the work of building a plant actually begun.
The Snoqualmie River is formed by the union of three widely divergent forks which drain a large section of the western slope of the Cascade Mountains. The water-shed is said to be about 460 square miles in area, and the rainfall is placed at 85 inches a year. During the heat of summer the melted snow from the mountain summits keeps up the supply of water. At the lowest stages of the water the power of the falls is placed by conservative calculation at from 20,000 to 30,000 horse power. The plant now going in will have capacity to deliver 6,000 horse power of this in the cities named, after deducting all losses. Provision is also made for extension.
The cataract is a very picturesque and impressive one, and it is situated in a sparsely settled and thickly wooded country. The central view in the group of pictures on this page (Fig. 1) shows the crest and upper portion of the falls, and Figs. 6 and 7 on page 100 show the character of the country thereabouts.
Briefly stated, the plan comprises an intake in the channel of the river about 300 feet above the falls; a shaft 250 feet thereunder, with a steel pipe to contain the column of water; a large excavation at the foot of the shaft, containing a receiver for the water, water-wheels, generators, transformers and switchboard; a tunnel or tail-race, through which the water flows from the water-wheels to a portal at the lower level of the river, and an electric transmission line from the subterranean power house to the distant points of consumption.
Mr. Charles H. Baker of Seattle, who is the president of the company and its chief promoter, was in Chicago last week to place contracts for the electrical equipment of the plant and to transact other business connected with the work. He states that the shaft is nearly down to the required depth; that the rock excavation for the power-house chamber is within two months of completion and that the tunnel is finished. The shaft is 250 feet deep and eight by 25 feet in horizontal section; the chamber at the base of the shaft will be 200 feet long, 50 feet wide and 25 feet high, while the tunnel leading from it is 660 feet long 15 feet high and 15 feet wide. The rock is hard and free from fissures. The excavation is done by compressed-air drills.
A general.view of the construction works is shown in Fig. 2, while Fig. 3 gives a nearer view of the air-compressing and hoisting machinery, Fig. 4 shows the interior of the tunnel and the tramway used