After 14 months of work, costing US$42M, work has finished on the seismic upgrade of the 40-year-old, 102m high Casitas dam on a tributary of the Ventura river in southern California, US. The upgrade included widening the dam crest; building a stabilising berm; removing and replacing liquefiable materials from the dam foundation.
The upgrade was undertaken after a 1995 study by the US Bureau of Reclamation showed it to be vulnerable to strong ground motion and liquefaction. The dam can now withstand a maximum credible earthquake of magnitude 7.2, the strongest expected in the area.
