After a Kiewit employee detected a leak early on Jan. 20 in a temporary cofferdam protecting workers and downstream interests on the $900-million Folsom Dam Auxiliary Spillway Project in California, the U.S. Army Corps of Engineers evacuated a dozen crew members and equipment while the U.S. Bureau of Reclamation (USBR) closed the bulkhead gates to prevent catastrophic flooding in the event of a cofferdam failure.