SACRAMENTO (AP) — The costs to repair the nation’s tallest dam after a nearly catastrophic failure of the spillways will top $500 million, nearly double the original estimate of $275 million, a California Department of Water Resources official said Thursday.
The $500 million figure reflects only the work by the main construction contractor, Kiewit Corp., to repair the spillways at the 770-foot Oroville Dam, said Erin Mellon, a spokeswoman for the state water agency. It excludes the costs of other contractors and the emergency response in the immediate aftermath of the spillway failure, which prompted fears of massive flooding. Nearly 200,000 were ordered to evacuate, but disaster was averted.
Construction crews are excavating unstable dirt, replacing it with concrete and topping it with rebar-reinforced concrete that is anchored into the bedrock.
The project has required far more excavation and concrete than expected, said Jeff Petersen, a Kiewit vice president who is directing the project. The state has also revised plans to shore up the emergency spillway, doubling the amount of concrete it will require.
Kiewit was hired in April to lead the repair work through Jan. 1, 2019. The company will rebuild the main spillway, place a 65-foot underground wall to stop erosion on the emergency spillway and lay concrete at least 10 feet thick between the cutoff wall and a concrete weir that holds water in the lake.
Barring a major storm or equipment failure, Kiewit’s 700 workers and subcontractors are on track to finish pouring concrete on the main spillway by Nov. 1, Petersen said. That will give the surface a month to cure and be ready for use in December.
“I don’t want to jinx it, but we’re ahead of schedule,” Petersen told reporters during a tour of the jobsite Thursday.
The cost for emergency response during the evacuation and its immediate aftermath is estimated between $140 million and $160 million, Mellon said.
State officials hope the Federal Emergency Management Agency will foot up to 75 percent of the repair bill, while the rest would likely be borne by State Water Project customers. FEMA has already reimbursed some costs for emergency response, but it’s unclear if the agency will fund the long-term repair work.
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