CWA approves consultant contract amendment for San Onofre desal feasibility study

The San Diego County Water Authority board approved an amendment to the professional services contract for the feasibility study of a seawater desalination plant at the San Onofre Nuclear Generating Station.

The November 30 vote authorizes the evaluation of a reconfigured desalination project which would limit the use of Unit 1 tunnels to discharge only and would utilize subsurface intakes to be constructed at a distance from the San Onofre Nuclear Generating Station. The revised study scope would also evaluate other locations to the south along the Camp Pendleton coastline and would consider discharge options, including the possibility of combining the concentrate discharge with existing treated wastewater discharges from nearby facilities in a new or expanded outfall.

Although there is no current change to the contract amount, the amendments also extend the completion date of the study from October 31, 2007, to June 30, 2008.

The proposed desalination plant would provide desalinated water to the San Diego County Water Authority, the Municipal Water District of Orange County, and Marine Corps Base Camp Pendleton. The facility is on Camp Pendleton, and the San Onofre Nuclear Generating Station is operated by Southern California Edison, which is also the majority owner of the nuclear power plant. The desalination plant would provide 50 to 100 million gallons per day.

In 2005 the County Water Authority and the Municipal Water District of Orange County completed a pre-feasibility study which identified no fatal flaws at two potential sites. In November 2005 the CWA in coordination with MWDOC executed a professional services contract with RBF Consulting to conduct a detailed feasibility study which also includes detailed feasibility evaluations of conveyance, intake, and discharge. Work completed so far includes data collection, analysis of conveyance alternatives, coordination with the Metropolitan Water District of Southern California on coastal pipeline planning, and identification of subsurface intake alternatives.

Shortly after the study began, Southern California Edison expressed concerns about the potential development of a desalination project adjacent to the power plant. Those concerns, which had not been raised prior to the preparation of the assessment, focus on the possibility that the presence and operation of a desalination facility may complicate the operation of the nuclear power plant and hinder future regulatory compliance. After those concerns were raised, CWA staff began working with SCE and Camp Pendleton on those issues while tasks directly affected by those concerns such as work on the sites adjacent to SONGS and the detailed evaluation of the potential re-use of the Unit 1 tunnels have been deferred.

The CWA has sent a letter to Camp Pendleton requesting comments from the primary San Onofre area stakeholders, which include California State Parks as well as Camp Pendleton and SCE, about a proposed study scope revision to evaluate a reconfigured project which would limit the use of Unit 1 tunnels to discharge only while utilizing subsurface intakes to be constructed at a distance away from SONGS.

The consideration of locations to the south along the Camp Pendleton coastline could be a net advantage to the CWA since that would reduce the distance required to convey the water to the CWA service area. A subsurface intake could also possibly eliminate marine life concerns which are inherent with open ocean intakes. That reduction to marine life impacts may increase the chances of California Coastal Commission approval of the project, although a new open ocean intake to the south is also one of the added options under the revised scope.