Construction crews in the next few months will begin the main construction phase of the San Vicente Dam Raise Project, the largest dam-raise project in the U.S. and the largest of its kind in the world.
The San Diego County Water Authority Board of Directors on April 22 approved awarding a $140.2 million contract for the application of roller-compacted concrete to raise the existing dam by 117 feet, which will increase the reservoir’s capacity by 169 percent. The joint venture partnership Shimmick Construction Company Inc. /Obayashi Corporation was selected after a competitive bidding process that drew interest from companies around the globe.
“The San Vicente Dam Raise project is a critical part of the Water Authority’s $1.5 billion plan to ensure that our region can call upon locally stored water reserves during emergencies or other periods of limited imported supplies,” said Maureen Stapleton, Water Authority General Manager. “In addition to its importance to regional water supply reliability, this project also brings major economic benefits, creating 5,500 job-years of employment to the San Diego region.”
The dam, which is owned by the city of San Diego, is currently 220 feet tall. By raising the dam to 337 feet, the expanded reservoir will provide 152,000 acre-feet of additional water storage. Of that amount, 100,000 acre-feet will be dedicated to carryover storage – water stored in wet years for use during subsequent dry years. An additional 52,000 acre-feet of the increased storage will be dedicated for emergency storage. (An acre-foot is 325,900 gallons, enough to meet the needs of two single-family homes of four people for a year.)
The project is also the largest component of the fourth and final phase of the Water Authority’s Emergency Storage Project (ESP). The ESP, which has been under development for more than a decade, is a system of reservoirs, pipelines, and other facilities that work together to store and move water around the county in the aftermath of a disaster, such as an earthquake. When complete, the entire ESP system will provide more than 90,000 acre-feet of water stored locally for emergency use, enough to supply the region for up to six months.
In addition to raising the dam, the construction phase covered by the new contract will include construction of a new saddle dam, a new outlet tower, a new pipeline and control facility and new access roads. Construction is expected to be complete by early 2013.
Water Authority construction projects such as the San Vicente Dam Raise are funded through bond sale proceeds. In January 2010, the Water Authority successfully completed a $627 million bond sale to provide funds for capital improvement projects for fiscal years 2011 and 2012. Because the bid awarded for this portion of the dam raise construction was significantly below Water Authority estimates, savings derived from the lower bid will allow the funds from the bond sale to be used over a longer period of time.
Shimmick Construction Company, based in Oakland, Calif., and Obayashi Corporation, based in Tokyo, Japan, have completed a number of roller compacted concrete and conventional concrete dams and dam rehabilitation projects over the past 10 years.
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