Document text
Divers inspect concrete structures at Lemolo Lake Dam Sunday Nov 6, 2016 at 12:01 AM By Emily Hoard Roseburg News-Review LEMOLO LAKE — This week, contractors are diving 90 feet underwater to inspect the concrete face, towers and structures of the Lemolo Lake Dam, as required by the Federal Energy Regulatory Commission. “We’re doing this in preparation for a five-year independent consultant dam safety inspection, which is going to occur in 2017 and 2018 as part of a group requirement,” said Mark Reeves, dam safety engineer. “We hired Ballard Marine Construction to dive all these submerged concrete structures and verify our belief that the structures are of sound construction after so many years.” While one diver at a time inspects the structure underwater, four crew members run the compressors, air mixer, generators, video system and hose. Ballard’s underwater dam inspection crew out of Washougal, Washington, began the inspections Monday. PacifiCorp, the owner and operator of the North Umpqua Hydroelectric Project, has been overseeing the work. “The inspections are just part of Pacific Power’s ongoing efforts to keep all the facilities and the people safe up here while we generate electricity,” Aquatic Scientist Rich Grost said. The dam and flow controls are inspected routinely, though this inspection has a more in-depth focus on the conditions of the concrete. “This is the most detailed inspection we’ve done at Lemolo Dam for concrete,” Grost said. The inspectors are checking for any deterioration or corrosion as well as looking at the condition of the concrete construction joints, connections to the gate rails and the trash rack, a gate that keeps debris from entering the turbines. Until this weekend, when the work is expected to be finished, the portion of Forest Service Road 2610, known as Bird’s Point Road, over the Lemolo Dam will continue to be closed. A detour route on Forest Service roads 2614 and 2612 is accessible along the south and north edges of the laker. Pacific Power drains down the lake every fall to increase the flow, improving habitat for spawning salmon downstream from Slide Creek Dam and to make space in the lake for future rain and snowmelt. While the lake will remain open for fishing, the boat ramps are not usable at the low water level. Pacific Power used its heavy equipment at Lemolo Resort to launch the dive boat for the inspections. Known for brown trout, rainbow trout and kokanee, the lake covers an area of 450 acres when full, but currently covers only 250 acres and sits about 23 feet below the normal water level. From the dam, water flows to the river and through the canal supplying the hydropower turbines downstream. The dam was built in 1954 and began operating in 1955. The Lemolo Lake Dam was the seventh of eight dams built for the North Umpqua Hydroelectric Project, and is the farthest upstream.