The 17,000-Horsepower Plan to Electrify Seattle

While the arrangements for the development of the power of Snoqualmie Falls have only just been completed, the plans for bringing together the power of the falls and the generators which are to put it in marketable form have long been ready and will this year be carried out, almost if not quite, as originally drawn. The first survey of the ground and plan for conducting the water to turbine wheels was made in the fall of 1889 by B. H. Thomson, now city engineer. His present public duties prevent him from devoting his time to the work, but his plans have been approved by the best engineers in the country and adopted for execution. The purpose is to build a small reservoir on the south side of the river about 300 feet east of and above the falls, into which the water to be used in generating power will pass through a bank of strainers intended to keep out debris, ice, etc. From the reservoir the water will be conveyed to the wheels, located in the power house on the river’s edge about 300 feet west of the falls, by a riveted steel pipe about 800 feet long and 84 inches in diameter, which will descend at an angle of about 20 degrees, with a vertical fall of 275 feet. For the first 300 feet the pipe will be laid in a tunnel driven through the basalt cliff lining the side of the gorge into which the river plunges, and for the remaining 400 feet it will rest on the ground. The column of water, 84 inches in diameter, carried by this pipe, with an initial head of 25 feet from the depth of water in the reservoir, will generate 17,000 horsepower at the wheels. It has not yet been determined whether turbine or Pelton wheels will be used, or some modification of the turbine, but in any case they will be placed in the brick power house, where the great column of water will beat down upon them. If turbines are used, the water will be taken out at the side of the main pipe through small outlets called nipples, from each of which revolve a pair of wheels generating 2,230 horsepower. If Pelton wheels are used, it will be taken out through small nozzles, each wheel generating about 600 horsepower. The Pelton wheels would be about twenty-four inches in diameter and the turbines about nine feet. From the wheel shafts the power will be transmitted to generators either directly or by belting, a point remaining to be settled by the electrical engineer who will have charge of the installation of the plant. From the power house the electric current will be conveyed by heavy copper wire stretched on poles, running in almost a direct line to the city, a distance of about twenty-three miles. It has not been decided whether the current shall be brought by cables under Lakes Sammamish and Washington or carried on a land line. Every precaution will be taken to prevent the breaking of the conductor by falling trees, and with this end in view all trees tall enough to reach it will be felled, so that a swath several hundred feet wide will have to be partly cleared. It is anticipated that the whole plant can be installed and put in operation before next winter sets in.