Reclamation plans work at Mormon Island, Stampede dams
The U.S. Departmefnt of the Interior's Bureau of Reclamation received bids for planned dam safety civil construction including an overlay of Mormon Island Auxiliary Dam, part of the 198.72-MW Folsom Dam hydroelectric project on California's American River.
The agency solicited information in January on firms able to perform the work. It proposes to modify Mormon Island Auxiliary Dam, one of 12 structures containing Folsom Lake, to improve its seismic stability. The U.S. Army Corps of Engineers has begun other work on a new flood control spillway at nearby Folsom Dam.
Work is to include excavation of existing embankments; importing 450,000 cubic yards of processed filter and gravel drain material; placement of 1 million cubic yards of shell-fill material from an existing stockpile; and excavation at the dam toe to install drain systems of pipe and filter material. The work is expected to cost $25 million to $100 million.
The bureau also received bids for dam safety civil construction at 3.65-MW Stampede Dam on California's Little Truckee River.
Reclamation conducted an industry day in November 2012 to discuss the work. Stampede Dam is part of Reclamation's Washoe Project, which also includes Marble Bluff Dam and Prosser Creek Dam.
The agency issued a draft environmental assessment in 2011 endorsing a plan to modify Stampede Dam to prevent its failure during extreme floods by increasing the height of the 239-foot-tall zoned earth fill dam by 11.5 feet. Reclamation performed risk analyses, finding the dam cannot safely pass floodwaters in accordance with Reclamation's Public Protection Guidelines.
Work to be performed will include removing existing concrete features; excavating the existing dam and dikes embankment; installing dam and dike, filter, and gravel drain materials to increase height of dam and dikes; increasing the height of the dam with a mechanically stabilized earth wall; constructing a new spillway crest structure of cast-in-place concrete; modify and install new dam instrumentation; and construct saddle dikes.
The work is valued at $10 million to $25 million.
Colorado plans repairs at Beaver Creek Reservoir
Colorado Parks and Wildlife will begin a two-year repair project to increase dam safety at Beaver Creek Reservoir in summer 2013, allowing its 4,400-acre-foot reservoir to be filled again by mid-2015.
The reservoir is an important component in the overall water management system in the San Luis Valley, and its water is used for irrigation, recreation and wildlife habitat.
According to the agency, the reservoir has been drawn down to about half its capacity since problems with the dam structure were discovered in 2010.
The US$15 million project will be conducted in two stages, with the first beginning in July. This phase will see the dam's spillway rebuilt. Work is expected to be complete in December.
Next, Colorado Parks and Wildlife said it will build a new abutment support for the dam and make improvements to the outlet tunnel. This portion of the rehabilitation is expected to begin in April 2014 and be complete by the end of that year.
Canada improving dam safety with Bolsover replacement
The Canadian government has awarded Metric Contracting Services Inc. a US$20.3 million contract to improve dam safety along the Trent-Severn Waterway in southern Ontario.
The Trent-Severn Waterway is a canal route with 125 dams, 26 of which impound water for hydroelectric plants that combine to have a total installed capacity of 100 MW.
Located at Lock 37 on this waterway, Bolsover Dam was built in 1902 and 1903. Under the terms of the contract, Metric Contracting Services will replace the dam, which was identified for replacement because of its aging infrastructure as part of Parks Canada's ongoing assessment modeling and recapitalization program.
The project's design, tendering, and construction will be managed by Public Works and Government Services Canada, with work expected to begin this year. The replacement is expected to take about two years.
In March 2013, we reported that the name of the system Engineered Solutions used to repair joint leaks at Wanapum Dam was RWS-G5, which is the former brand name. The product installed is actually called CYLutions. The editors regret the error.