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By Millicent Arko
January 2, 2012 (San Diego)-The tallest dam raise in the United States is under construction in Lakeside at the San Vicente Reservoir. Now the San Diego County Water Authority has set up a web cam where you can view the progress live. High-resolution photos are updated every 30 minutes, providing a current snapshot. The time-lapse sequences combine photos, illustrating the construction process with two vantage points of construction.
View the webcam at http://www.sdcwa.org/san-vicente-dam-raise
Construction to raise the height of the dam by 117 ft to more than double its reservoir size has been underway since June 2009 and is set for completion in 2013. It will be the largest dam raise in the United States and largest roller-compacted concrete (RCC) dam raise in the world. The raised dam will store an additional 152,000 acre-feet of water, more than doubling the capacity of the reservoir.
About the Dam: The San Vicente Dam is a concrete gravity dam on San Vicente Creek, built to provide a municipal water supply, flood control and recreation. Although the reservoir is fed by run-off, the main source is the First San Diego Aqueduct.
Roller-compacted concrete (RCC) or rolled concrete - is a special blend of concrete with essentially the same ingredients as conventional concrete
but in different ratios, with much less water. The material is placed in a manner similar to paving, delivered by dump trucks or conveyors, spread by small bulldozers or specially modified asphalt pavers, and then compacted by vibratory rollers. Benefits of RCC include higher rates of concrete placement and lower costs.
but in different ratios, with much less water. The material is placed in a manner similar to paving, delivered by dump trucks or conveyors, spread by small bulldozers or specially modified asphalt pavers, and then compacted by vibratory rollers. Benefits of RCC include higher rates of concrete placement and lower costs.Hisory - In the late 19th century, San Diego began building dams to help supply municipal water, mitigate drought and control floods along the San Diego River. In San Diego residents had initially rejected proposals to build the San Vicente Dam in 1939, but faced with a growing population in the city, voters approved funding in 1940. Constrution begain in 1940. In 1943, the city of San Diego completed construction on the 220-foot-tall San Vicente Dam to store up to 90,000 acre-feet of water. But construction on the First San Diego Aqueduct, which was supplied by the Colorado River Aqueduct, did not begin until 1945. In 1947, the First Aqueduct was complete and the San Vicente Reservoir began to receive its water.
Dam raising project - As part of the SDCWA's $1 billion Emergency Storage Project which began in 2000, the San Vicente Dam Raise will increase the height of the 220 ft dam by 117 ft to 337 ft. This will double the reservoir's current capacity of 145,200,000 cubic yards by increasing it to 245,226,666 cubic yards to a total of 390,426,666 cubic yards. The original designers had predicted that raising the dam would be needed in the future and positioned the dam so that the height could be increased by up to 120 feet. The raised dam will be 337 feet tall and will be made of roller-compacted concrete. This is a rendering of the completed dam, developed by the construction management team. The dam will be stained to help it blend in with its surroundings.
In 2006, the SDCWA awarded a $20.4 million contract which included developing the raised-dam's design and other engineering services during construction, which is being done in phases. The reservoir, which was closed for recreation when construction began, will reopen between 2014 and 2017 depending on when it reaches normal levels. The San Vicente Dam Raise itself is estimated to cost $568 million and will be complimented with a new pumping facility and the San Vicente Pipeline which will connect the San Vicente Reservoir to the Second San Diego Aqueduct.
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