June 9, 2011

The saga of the spillway

The saga of the spillway
Gates open again after apron repairs

For the first time in the 57-year history of the Garrison Dam, the U.S. Army Corps of Engineers opened spillway gates June 1 to drain flood waters from Lake Sakakawea into the Missouri River.
But, like anything that lies dormant for nearly six decades, there’s bound to be some kinks.
Shortly after opening seven of the spillway’s 28 gates, releasing an additional 7,500 cubic feet per second of floodwater and bringing total releases to 92,500 cfs, engineers noticed a water spray caused by a “pothole” in the spillway’s apron. The Corps closed the gates to allow engineers to physically inspect the spillway apron, where they identified minor surface deterioration. The deterioration likely occurred as a result of natural freezing and thawing action on the apron over time.

The Weather Network