Kiewit Corp., a construction giant with extensive experience in dam projects, was awarded the massive repair job at troubled Oroville Dam on Monday. The California Department of Water Resources announced that Kiewit, based in Omaha, Neb., beat two competitors for the job with a $275.4 million bid. Kiewit had the low bid, although its offer was still higher than DWR’s internal estimate that the project would cost $231 million. (DWR said on Saturday that it estimated the project would cost $220 million, but released a corrected estimate Monday.)