In February of this year the nation’s tallest dam — the Oroville Dam — almost collapsed. The huge hole in the spillway during heavy rains had officials worried. If the worst happened it would have sent millions of gallons of water into heavily populated areas.
Just in case, they forced the evacuation of 200,000 people.
To ease the crisis, the state ended up releasing a lot of water downstream. That — and the forced evacuation — worried residents and farmers who filed suits seeking $1 billion in damages. Those suits are still being adjudicated.
Investigations have been going on since the crisis hit. The state of California is doing one and the association of State Dam Safety Officials and the U.S. Society on Dams are doing another. Both are still ongoing. In their first discussion about the incident since the investigations began, the dam safety group — via spokesman and dam expert John France — said bad design and construction 50-years ago is where the crisis began.
Lack of state and federal oversight after the dam was built contributed the rest. That and outside consultants who are supposed to do a thorough safety review of a dam every five years. France said the state — if it was paying attention — could have stopped the problem before it became a crisis. He noted clues to what to do were found in the state’s files on the dam if anyone had bothered to look but “there has never been an evaluation completely that went back thoroughly in the files.”
That leads us back to the every five-years investigation and its failure to make note of the dangers.
France said his group — the U.S. Society on Dams — hopes government officials will take what has been learned so far and apply it to other dams. And he says it needs to be done and soon noting the average dam in this country was built 50-years ago or more. All were built to what are now outdated standards.
The preliminary report France and his group issued said water got through cracks and the seams of repairs in the main spillway and caused it to crumble and fall. But that’s just part of the reason for the failure. The other part is — plain and simple — poor design with thin concrete on the spillway, drains placed in the wrong place and foundations that are not adequate.
Inspections — the dam experts and their first report said — would not have solved the problem, however he said they “would likely have connected the dots … by identifying the physical factors that led to failure.”
The California Department of Water Resources manages the dam. Spokeswoman Erin Mellon said the state is now on top of things. “The reconstruction efforts at Oroville will bring the spillway design and construction up to today’s standards to ensure we address the physical causes that led to the February failure,” she said.
Source links: Insurance Journal, The New York Times