Release no. 12-044
PORTLAND, ORE. – The U.S. Army Corps of Engineers awarded a $4.5 million contract July 18 to raise the spillway crest elevation of the existing Sediment Retention Structure at Mount St. Helens to LKE Corp. of Washougal, Wash. The SRS was constructed in the late 1980s to trap sediment from the debris avalanche on Mount St. Helens.
The contractor will raise the existing SRS spillway seven feet, which will increase sediment storage capacity to meet the near-term sediment management needs. The raised spillway will form a shallow pool behind the SRS to hold 2 million cubic yards that covers about 200 acres. The work includes excavating rock to construct a pool and low flow channel from a new roller-compacted concrete structure to the existing spillway crest.
The Corps is working with tribal, state and federal fish and wildlife agencies to ensure the Corps’ near-term sediment management actions will not impact downstream juvenile and adult fish passage, and ensure that long-term actions will provide the opportunity for upstream volitional fish passage in the North Fork Toutle River.
Mount St. Helens