Large dam upgrades in North America are squeezing every megawatt out of the grid as efficiently as possible by converting century-old powerhouses and replacing decades-old turbines. Construction is under way at several sites, from Pennsylvania to British Columbia. Earlier this month, PPL Montana began upgrading its Rainbow Dam, a 36-megawatt dam on the Missouri River, six miles northeast of Great Falls, Mont., where 200 workers are under the direction of Chicago’s Walsh Construction. Photo: Courtesy BC Hydro British Columbian utility will boost generating capacity at W.A.C. Bennett Dam by phasing in five replacement turbine units by 2017. PPL Montana says
King County, Wash., will begin removal of a stuck tunnel-boring machine inside the Brightwater Treatment Plant conveyance system, near Seattle, later this month. Replacement joint-venture contractor Jay Dee/Coluccio will spend $4 million to freeze the ground around the TBM’s cutter head, then cut apart and remove the machine by spring 2011.
It appears that 14 miles of 120-year-old sand-and-grass dike near Portage, Wis., has survived the flood-swollen Wisconsin River’s recent rise to a record-level 20.6-ft, or more than 3 ft above flood level. With the Wisconsin River&rsquos water level now dropping at about an inch an hour, the series of dikes, built by farmers in the 1890s and now maintained by the Wisconsin Dept. of Natural Resources, appears to be essentially intact, according to the DNR. “The river has dropped to 18.7 ft this morning, and is going down at about an inch per hour,” DNR spokesman Greg Matthews said Sept.
Hoover Dam, the Depression-era engineering marvel, turns 75 this month. While its new bridge crossing is set to open in November, the concrete monolith also is marking a dubious milestone this year—a 54-year low point for its water level, which threatens the dam’s hydroelectric output. Photo: Courtesy of Southern Nevada Water Authority Lake Mead reservoir level is at its lowest point in 54 years, putting electricity generation capability at risk. Engineered mitigation measures include a third water-intake tunnel and new turbine design. Lake Mead dipped to 1,085 ft in September, less than 40% of its capacity, following a decade of
The San Francisco Public Utility Commission’s $4.6-billion regional water-system improvement program is racing against the clock as the construction team retrofits facilities to withstand a potential earthquake that, according to the U.S. Geological Survey, could come at any time. Set for completion by December 2015, the Water System Improvement Program (WSIP) is a mammoth undertaking, consisting of 86 separate water-supply and storage projects spanning counties in northern and central California. Construction is well under way on some of the projects; others won’t break ground until 2011. Julie Labonte, the commission’s WSIP program director, says that while some of the projects
A four-year legal spat over the Hoover Dam bypass project’s collapsed cableways has ended in a private settlement stemming from an April 20 arbitration ruling. A joint venture of Obayashi Corp., San Francisco, with PSM Construction USA Inc., Brisbane, Calif., will reimburse American Bridge Co., Coraopolis, Pa., an undisclosed amount for a cableway system that broke in 2006, causing a two-year delay. In 2005, the joint venture signed a two-year, $105,000-a-month lease with American Bridge Co. to use two pairs of refurbished, 330-ft-tall lattice-framed towers with 2,500 ft of 3-in-dia. cableway strung between them. The so-called high lines function like
Barnard Construction Co. , Bozeman, Mont., won a $26.9-million contract from the National Park Service to remove the Elwha and Glines Canyon dams on the Elwha River in Washington State’s Olympic National Park. The firm’s bid was $13 million less than the engineer’s estimate. Site construction is set to start in September, with actual dismantling a year later. “With award of this contract, we begin the countdown to the largest dam removal and one of the largest restoration projects in U.S. history,” says Karen Gustin, park superintendent. The contract includes removal of the 108-ft-high Elwha Dam, completed in 1913, and
Tidal power in the U.S. moved toward commercial viability this summer when Portland, Maine-based Ocean Renewable Power Co. successfully produced electric power from a tidal turbine it installed in Cobscook Bay in Eastport, Maine. The tidal turbine was designed with assistance from the University of Maine and a Maine-based fabricator. Tidal power should be more viable in Maine than Arizona, where solar power has a bright future. “I would say that it’s an important step forward,” says Paul Jacobsen, ocean energy leader for the Electric Power Research Institute, Palo Alto, Calif., an organization that conducts electric research and development. It’s
Divers installing new control gates 150 ft below the surface of Cheesman Dam continue to blast, chop and saw-cut through granite to bring water-control systems on the 105-year-old dam up to modern standards. The dam, in the foothills 25 miles southwest of Denver, stores 80,000 acre ft of water to help meet the needs of Denver Water’s 1.3 million customers. When it was built in 1905, the 221-ft-tall brick-and-granite dam was the tallest in the world, but its cast-iron valves are rusty and unworkable, giving engineers no reliable upstream controls to shut the water off if something happens at the
During the dismantling of Gold Ray Dam, a 106-year-old timber cofferdam and 70-year-old concrete dam near Medford, Ore., the Rogue River blew through a sand spit, changed course and ran freely for the first time in more than a century. Photo: River Design Group Oregon’s Gold Ray Dam is razed two weeks ahead of schedule after an unexpected breach. Scott Wright, project manager for the Corvallis, Ore., office of design-build contractor River Design Group, says the entire process actually sped up the crew’s work by almost two weeks. Crews built two temporary sand-and-gravel cofferdams—one in the river and one in