As construction crews scramble to complete their multimillion-dollar repairs to the damaged Oroville Dam’s main and emergency spillways in time for the winter rains, here’s an exclusive, video look at their progress, assembled from recorded material from the state Department of Water Resources and our own animation based on plans for the project.
After the dam’s main and emergency spillway became heavily damaged during last February’s record-breaking rain storms, the state’s Department of Water Resources hired Omaha-based contractor Kiewit Corp. to rebuild them. The breach led to the evacuation of 188,000 downstream residents and threatened a number of nearby towns, pushing authorities into crisis mode as they launched a repair project that has already cost the state $640 million.
Phase one, which essentially recast the main spillway from the ground up, was completed at the beginning of this month, and the state and its contractors have said the dam is now breach-proof for the rainy season. By next year, the upper section of the spillway would be torn down and rebuilt — once done, the entire 3,000-foot-long spillway would be made of new construction. However, small cracks have recently appeared on the new concrete spillway, a development state officials say was expected but an engineering expert says could lead to serious safety issues.
In a previously undisclosed October letter, federal regulators asked Department of Water Resources officials to explain the hairline cracks on the dam’s new massive concrete flood-control chute, KQED radio of San Francisco reported earlier this week. The Federal Energy Regulatory Commission also asked water officials what, if any, steps might be required to address the issue.
Staff writer Patrick May contributed to this report.
