Village News Reporter
The Metropolitan Water District of Southern California will be replacing air release/vacuum valves on Pipeline 3 and Pipeline 5 of the San Diego Aqueduct, and the MWD board meeting Tuesday, May 9, approved a procurement contract for new valves.
B&K Valves & Equipment Inc., which is based in Carlsbad, was awarded $1,466,665 to provide 72 valves. MWD staff will replace the valves once they are delivered.
Six MWD pipelines carry water along the San Diego Aqueduct from MWD’s Robert A. Skinner Water Treatment Plant in Temecula. Pipelines 1, 2 and 4 convey treated water while Pipelines 3, 5 and 6 deliver untreated supply. Pipeline 6 currently carries untreated water for seven miles from Lake Skinner to Anza Road and De Portola Road; the southern portion which would serve San Diego County is not expected to be needed in the near future so that part of the project has been deferred.
The San Diego Aqueduct conveys water to a delivery point six miles south of the Riverside County line, which allowed MWD and the San Diego County Water Authority to provide equal contributions for the connection between MWD's Colorado River Aqueduct and the San Vicente Reservoir in Lakeside. MMD has been delivering water to San Diego County since 1947.
Pipeline 3 is 75 inches in diameter and consists of pre-cast concrete and welded steel sections. It was completed in 1960 and conveys up to 280 cubic feet per second of untreated water to the Western Municipal Water District and the San Diego County Water Authority. Pipeline 5 is 96 inches in diameter with pre-stressed concrete and welded steel pipe sections. It was completed in 1982 and conveys up to 500 cubic feet per second of untreated water to the SDCWA.
Both pipelines use combination air release/vacuum valves located at high points along the pipeline to protect the pipeline and maintain its efficiency. During operation or filling of the pipeline, air must be released when it builds up at high points or flow will be impeded. When the pipeline is dewatered air must be introduced into the pipeline, or a vacuum condition can develop inside the pipe which could cause collapse or buckling.
The 72 valves on the two pipelines range in size from eight to ten inches in diameter. The existing air release/vacuum valves are original equipment and have been in service for approximately 60 years on Pipeline 3 and 40 years on Pipeline 5. Air release/vacuum valves are normally open to release air or prevent a vacuum within the pipe, and as water level rises a float shuts off the valve. Failure of an aging float mechanism could lead to an unplanned water discharge.
All 72 valves will be replaced. The valves will be delivered to the Skinner plant where they will be stored in a controlled environment until they are scheduled for installation.
B&K Valves & Equipment submitted the only bid for the valves. MWD staff investigated why only one bid was received and determined that only a limited number of valve manufacturers routinely manufacture valves which meet the specifications required for the project. A survey of vendors provided a budgetary estimate between $1.2 million and $1.5 million for the valves. The B&K Valves & Equipment bid complies with the requirements of the specifications and includes all sales and use taxes imposed by the state of California.
The valves are expected to be delivered in June 2024.