The U.S. Army Corps of Engineers awarded a $770,000 contract Monday to J.E. McAmis, Inc., of Chico, Calif., to remove large rocks from the base of the spillway at Bonneville Lock and Dam.
After the record-breaking water flows at the Corps' Columbia River dams in 2011, engineers found large amounts of rock had accumulated below Bonneville's spillway gates, placed there by the force of the water. The rock moves around during spill operations, which means the large stones can damage the concrete structure below the spillway.
"Leaving the rock where it's at is not an option," said Matthew Cutts, Portland District critical infrastructure project manager. "If it were left unchecked, the rock could cause damage to the infrastructure and make repairs much more difficult and costly."
The contractor will have rock removal equipment on a barge and will use divers to assist with the underwater work to remove the rocks, Cutts said.
The work must be done by March 31 to ensure the Corps is ready to begin spilling water for juvenile fish migration in April.