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U.S. approves $250 million in improvements to 54.4-MW Snoqualmie Falls

The Federal Energy Regulatory Commission has approved plans by Puget Sound Energy to make $250 million in improvements to the Snoqualmie Falls hydroelectric project, adding 10 MW to bring the historic project to the full 54.4 MW authorized by its 2004 relicensing.

The 111-year-old project (No. 2493) features two power plants and Snoqualmie Falls, a 268-foot waterfall about 30 miles east of Seattle. Considered a sacred site by members of the Snoqualmie Tribe, the falls play a central role in the tribe’s creation story and are an important location for its religious practices as well as an attraction for 2 million visitors per year. (HydroWorld 10/20/08)

Puget said June 4, 2009, that a FERC license amendment approved in June will allow construction to ramp up in September on substantial upgrades to generating infrastructure and major enhancements to recreational facilities. The work is to be complete in 2014.

Work includes replacement of a generator in Plant 2 and replacement of a generator and retrofitting of four 1898-vintage generators in Plant 1, increasing generating capacity by 10 MW without using additional water. Puget also plans to replace intake structures, upgrade penstocks, install turbine bypass valves, and install automatic shutoff gates above Plant 2 to halt flows in the event of earthquake or other emergency.

Puget plans to refurbish the project’s concrete diversion dam above the falls, lowering it two feet and lengthening it 37 feet. The modifications are to reduce the crest of flood waters in the upstream city of Snoqualmie while providing better conveyance to PSE’s powerhouses.

After the 2004 approval of Snoqualmie Falls’ relicense, the Corps of Engineers altered the river channel upstream for flood-reduction purposes, changing the river’s bathymetry and prompting Puget to modify the dam under the new license amendment from FERC.

The utility also is to make significant improvements to park and recreational facilities, improving hiking trails, making better riverfront access to boaters, and building new recreation facilities and restrooms in the lower Plant 2 area.

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