A secret state Department of Water Resources memorandum explaining the hairline cracks in the Oroville Dam spillway is now public.
The document provides more details on how Kiewit Infrastructure West Co., the contractor for spillway reconstruction, tried to reduce shrinkage, which leads to cracking in concrete.
It also contains photos documenting the cracks.
Officials with the department maintain cracks were anticipated because the spillway is highly restrained and do not pose a threat to its structural integrity or require a fix.
Professor Robert Bea with U.C. Berkeley’s Center for Catastrophic Risk management said on Monday he found two of the pictures, figures one and three in the report which show thin and long breaks in the concrete, significant and “very scary.”