By: Nicholas K. Geranios
Pressure from the water behind Wanapum Dam may have contributed to the big crack that has disrupted operations at the structure, the Grant County Public Utility District said Wednesday.
The cause of the crack remains unknown, but the utility said it had ruled out four possibilities: seismic activity, foundation settlement, operation of spillway gates and explosions at the nearby Yakima Training Center operated by the U.S. Army.
Chuck Berrie, assistant general manager of the utility, said learning the cause could occur as soon as the next two or three weeks.
The 65-foot-long crack was detected by divers on Feb. 27, three days after a worker at the dam noticed that the top of a spillway pier had shifted slightly. When the reservoir behind the dam was drawn down by 26 feet, the pressure on the spillway was reduced and the fracture closed. Read more