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Noxon Rapids Dam - Noxon, MT
Posted by: Groundspeak Premium Member BK-Hunters
N 47° 57.739 W 115° 43.967
11T E 594596 N 5312888
Quick Description: Downriver on the Clark Fork River 33 miles from the Thompson Falls Hydro Project, the $85 million Noxon Dam and Powerhouse were built in the years 1956 to 1959. It is also 22 miles upstream from the Cabinet Gorge Hydro Project in Idaho.
Location: Montana, United States
Date Posted: 5/21/2014 8:53:30 PM
Waymark Code: WMKRDC
Published By: Groundspeak Premium Member lumbricus
Views: 0

Long Description:
The earth filled gravity dam itself is a mile long, 260 feet high and 700 feet wide at the base, providing a head of something over 150 feet at the turbines.

The powerhouse measures 485 feet by 105 feet and required 69,952 cubic ards of concrete and 3,220,977 pounds of reinforcing steel. Concrete work was concluded on July 3, 1959 and the powerhouse went online that same month. By 1977, after the addition of the fifth generator, the dam was producing 554 megawatts of power.

The Washington Water Power Company (now Avista Corporation) of Spokane, Washington, formally contracted with Ebasco Services Incorporated (Ebasco) of New York, New York, for engineering and construction management services for building the Noxon Rapids Hydroelectric Development on March 1, 1955. Construction activities started on August 17, 1955, with reservoir clearing. Construction activities were completed on July 9, 1960, when the dedication ceremonies were held at the facility.

The primary construction contractor for the dam and powerhouse was the Morrison-Knudsen Company. Much of the electrical work at the powerhouse was done by the Morgan Electric Company. Special construction assistance was provided by the General Electric Corporation, Westinghouse Electric Corporation, and Allis-Chalmers Corporation.

The Noxon Powerhouse was originally equipped with four vertical water- turbine-driven alternating current generators manufactured by General Electric. Each of the four original generators is a Type ATB-W-72 pole with the following specifications: "88,400 kva, .8 pf, 100 rpm, 14,400 volts, 3 phase, 60 cycles, (70,720 kw, 3,544 amp arm, 1,050 amp field) with Type EVF-12,12 pole, and Type EV-11, 6 pole, 14 kw, 250 volts, 100 rpm compound wound pilot exciters". The generators are enclosed in outdoor type weatherproof metal housings located on the powerhouse roof deck. A fifth generator unit was installed in 1976.

The original four turbines installed were single runner, vertical shaft, Francis-type hydraulic turbines capable of 100 revolutions per minute (rpm), 130,800 hp at 152 foot head. These turbines were manufactured by the Allis-Chalmers Manufacturing Company of Milwaukee, Wisconsin.

The turbines drew power from Noxon Reservoir, which stands 38 miles long and 1.3 miles wide at its widest point. Total storage capacity of the reservoir is an impressive 400,000 acre ft of water, with an active storage in the top 10 feet of approximately 80,000 acre feet. The reservoir not only altered the landscape of the region, it also altered the economy of the region.

The dam itself was nearly a mile long at completion, and created a reservoir with a surface area of approximately 8,650 acres and a shoreline of over 100 miles.
From the Historic American Engineering Record


Waterway where the dam is located: Clark Fork River

Main use of the Water Dam: Hydroelectric Power Production

Material used in the structure: embankment

Height of Dam: 260 feet

Date built: 7/3/1959

Fishing Allowed: yes

Motor Sports Allowed: yes

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