Complete failure at Oroville Dam
The $1.1 billion spent to repair Oroville Dam is failing as water is seeping through the rebuilt spillway threatens new mass evacuations over the risk of the dam collapsing.
According to national dam expert Scott Cahill of Watershed Services of Ohio, Oroville Dam is on the same failure track as in 2017, with visible water seepage trickling from the foot of the dam and dozens of points along the dam’s principal spillway. Cahill warns that warming temperatures magnified by precipitation is a growing threat to the dam.
American Thinker reported on March 1 that the Sierra snow-pack was at a record 113 inches, but another 44 inches fell in the next 10 days. With temperatures spiking this week to 75 degrees in the valleys and 41 degrees in the high mountains, dam inflows are running twice the outflows and the water levels rose from 800 to 839 feet.
As America’s tallest earthen dam with a 770-foot face and 901-foot top of the spillway, the lake behind Oroville Dam can hold 3.5 million-acre feet of water. Its viability is a crucial element for the effectiveness of California’s system of 1,250 flood-control dams.
The last time the water level rose to 815-feet in February 2017 and engineers began opening eight huge spillway gates to allow 100,000-acre feet per second to race down the face of the dam, the spillway’s midsection began seeping water at many points.
The difference of the huge water pressure on the dam and the lower pressure from water running down the spillway caused the huge cement plates to rise and fall. As water seepage turned into porting streams, the spillway buckled and then washed away.
Facing the risk of a 30-foot wall of water racing toward metropolitan Sacramento, the Butte County Sheriff issued a mandatory evacuation of 188,000 residents.
The rains ebbed and the dam survived, but the Federal Energy Regulatory Commission’s after-action 537-page Independent Forensic Team Report found:
“The Oroville Dam spillway incident was caused by a long-term systemic failure of the California Department of Water Resources (DWR), regulatory, and general industry practices to recognize and address inherent spillway design and construction weaknesses, poor bedrock quality, and deteriorated service spillway chute conditions.”
Read more:
No comments:
Post a Comment