First anchors installed at Wanapum Dam
Construction workers feed cables into a 200-foot hole at Wanapum Dam, among the first of 35 cables that will help reinforce the structure. Grant County PUD employees found a crack in the dam in February.
WANAPUM DAM - Repairs to Wanapum Dam will spill over into 2015, although enough work will be completed to partially raise the water level behind the dam sometime before the end of the year, according to PUD officials.
The first anchors in the dam were installed about Sept. 3, according to a press release from the Grant County PUD.
Utility district employees discovered a crack in one of the spillway pillars in February, and immediately lowered the water level behind the dam. Currently the water is about 26 feet below the normal operating range, the press release said.
"Until the reservoir is raised, the shoreline and access points will remain closed to the public," the press release said.
A PUD analysis team discovered the ultimate source of the crack was a mathematical error in the original design, and the same error affected construction of the entire dam. As a result the team recommended reinforcing all the spillways.
The repair plan calls for drilling holes vertically through the dam into bedrock and installing 35 cables, called anchor tendons, across the span of the dam. Each cable is stretched tight and the holes filled with concrete. About 50 additional steel anchor bars are being installed in the cracked spillway.
Currently the cost of repairs is estimated at about $69 million, about $8 million over the original estimate. The PUD's "strong financial position allows the utility to pay for its proportionate share of the cost by using cash reserves and selling bonds. The utility isn't expecting any revenue increases for retail customers beyond the previously planned 2 percent increase included in the current forecast," the press release said.
While the water is low the PUD has been working on improvements at the Vantage and Frenchman Coulee boat launches, and removing sediment at the Crescent Bar boat launch. The low water gave the PUD the chance to do the work for less money, the press release said.
Wanapum Dam has two fish ladders, which had to be modified to accommodate the low water. The modifications worked, PUD officials said. More than 700,000 salmon and steelhead made the journey upstream to date, the press release said.