- Associated Press - Wednesday, March 12, 2014

WANAPUM DAM, Wash. (AP) - The Grant County Public Utility District is exploring the possibility of using steel anchors to repair its cracked Wanapum Dam on the Columbia River.

The steel strand anchors would be drilled from the top of the dam through the concrete structure into bedrock, and they would be set into place with a specialized grout, the utility said Wednesday.

The utility is working with federal regulators and an independent board in deciding how to repair the dam.

The 50-year-old dam is six miles south of Vantage and the Interstate 90 bridge in central Washington.

A crack that was about 65 feet long and about 2 inches wide was discovered on a spillway pier on Feb. 27. The crack is below the waterline of the dam.

Officials do not know what caused the crack, but they said the dam is not in danger of failing.

The utility said contractor Kuney-Goebel JV will begin investigative drilling into the spillway pier on Thursday.

“The precise-drilling project is expected to take about nine days to complete,” the utility said in a news release.

The drilling is expected to help determine the cause of the fracture.

No additional damage to the dam was found during a thorough inspection, other than some minor surface damage on spillways neighboring the cracked one, the utility said.

In addition, fish biologists, engineers and stakeholders are developing plans to modify the fish ladders at Wanapum Dam, which are no longer functional.

Those modifications would include installing a pumping system and creating temporary slides at the top of the fish ladders so returning adult salmon and steelhead can safely pass through the dam and into the drawn-down reservoir. Adult fish will start heading upriver to spawn in late April and continue until November.

The level of the reservoir has been dropped by 26 feet to relieve pressure on the dam. That drawdown has reduced power generation from about 700 megawatts to 360 megawatts.

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