HALF MOON BAY, CA
Alves Water Tank Seismic Retrofit
Cornerstone Structural Engineering Group was retained by Pakpour Consulting Group to prepare a Structural Review and Retrofit Strategy Report for an existing welded steel water storage tank at the Alves tank site in Coastside County Water District. The existing tank at the Alves site is approximately 25 feet 6 inches tall, with a diameter of 120 feet for a total storage capacity of 2.0 million gallons. This conditional and seismic assessment included multiple site visits, assessment of existing corrosion and paint, calculations in accordance with AWWA D100-11 design code, documenting potential areas of concern, potential retrofit options and recommendations, and proposal of lowering the normal operating level and addressing conditional issues and repainting.
Cornerstone Structural Engineering Group worked closely with Coastside County Water District to obtain available as-built information and consulted a tank manufacturer to determine potential retrofit strategies. The final report also included various retrofit sketches and construction cost estimates which were vetted by a tank manufacturer. Ultimately, the District elected to lower the water level to mitigate seismic deficiencies and address conditional issued noted. Upon approval of the seismic evaluation and conditional assessment report, Cornerstone Structural Engineering Group worked closely with Pakpour Consulting and the Water District to deliver final plans, specifications, and estimates of the tank modifications including providing details for repairing and replacing corroded rafters, enlarging an existing manhole, and installation of a flush cleanout and catch basin.