The Washington state dam where inspectors found a 65-foot-long crack last week has fixed itself and is now safe, utility officials said Wednesday.
Federal regulators and consultants rushed to Wanapum Dam — on the Columbia River near the central Washington town of Vantage — after the discovery of the 2-inch-wide crack last week in a spillway pier triggered an emergency alert.
A spillway is part of a dam that helps control the release of water downstream, letting it spill over the dam rather than slice through its turbines.
Grant County Public Utility District
The crack was found last week in the fourth of 12 spillway piers at Wanapum Dam on the Columbia River, as shown in this photo delivered as part of a report Tuesday night to the Grant County, Wash., Public Utility District.
Grant County was under a flash flood watch because of the potential for uncontrolled water flow as water levels along the 8,320-foot-long dam were drawn down about 26 feet — about 3 feet a day. That was done to reduce pressure on the structure and allow the crack to close.
It worked — integrity surveys showed not only that the spillway was stable but also that "the fracture has closed," Tom Stredwick, a spokesman for the Grant County Public Utility District, said Wednesday.
The breach relaxed back into place thanks to the lower pressure pushing against it, and the utility district downgraded the dam's status late Tuesday to "non-failure emergency" while it seeks a permanent repair.
The dam is producing only about half its maximum power capacity, however, partly because three of its 10 turbines were already offline for maintenance. All boat launches on Priest Rapids and Wanapum reservoirs remained closed.
— M. Alex Johnson
First published March 5 2014, 9:16 PM