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Water Authority to test seawater intake technologies at Camp Pendleton

The San Diego County Water Authority's board of directors approved a new agreement with U.S. Marine Corps Base Camp Pendleton to study seawater intake options for a potential desalination project on the base. The board also authorized a $4.05 million contract for building, operating and reporting on a pilot-scale seawater intake testing program that's expected to take about two years.

A potential Camp Pendleton desalination project is viewed by the Water Authority as a long-term water supply option for the region that could come online after 2030. In the near-term, the next increment of local water supply for the region is expected to be purified water projects under development by Water Authority member agencies. The board will have several opportunities over the next decade to make decisions about advancing a potential Camp Pendleton project in light of future regional water supplies and demands.

The Water Authority has been working with base officials since 2007 on feasibility and technical studies for a seawater desalination project at the southwest corner of the base that would produce 50 million gallons to 150 million gallons a day. Such a facility could provide a unique and strategic opportunity to help meet the region's future water needs and support vital national defense operations. If the Board and the base decide to move ahead with a full-scale project in the future, it would take a decade or more to complete.

The Memorandum of Understanding with Camp Pendleton does not commit either party to advance the project beyond the testing activities, which are designed to address project planning and future permitting issues related to the viability of subsurface and screened ocean intake systems and related pre-treatment facilities. The newly authorized intake studies contract is with Michael Baker International, an engineering and consulting firm with extensive experience at other seawater desalination projects under development in California.

The board's actions are consistent with the Water Authority's Regional Water Facilities Optimization and Master Plan Update completed in 2014. While that plan identified local potable reuse projects as the next likely source of supply, it recommended an "adaptive management" approach to a potential Camp Pendleton desalination project. That means major decisions regarding the project will take into account progress with the implementation of other local water supplies currently under development, progress on upgrades to the Sacramento-San Joaquin Bay-Delta, and changes in imported water supply reliability.

A 2009 feasibility study by the Water Authority found that Camp Pendleton's location at the northern end of the Water Authority's service area is ideal for efficiently integrating a potential new water supply into the regional water distribution system for countywide use. In close coordination with Camp Pendleton officials, the Water Authority identified two possible sites for a desalination plant near Interstate 5 and the mouth of the Santa Margarita River. Both sites could support an initial 50 million gallon per day desalination plant, and both have the capacity for expansion to 150 million gallons per day. A new system of pumps, pipelines and storage tanks would be needed to integrate a new plant into the Water Authority's water delivery infrastructure.

In 2012, the Water Authority's Board approved a Water Purchase Agreement with Poseidon Water for the company to build a 50 million gallon per day seawater desalination plant in Carlsbad, along with a 10-mile pipeline to the Water Authority's aqueduct in San Marcos. The $1 billion project, which includes upgrades to the Water Authority's infrastructure, is nearly complete and expected to start commercial production in late fall 2015. It will be the largest seawater desalination project in the nation, meeting 7 to 10 percent of the region's demand.

Unlike the Carlsbad project, which will use existing seawater intake and discharge facilities for the adjacent Encina Power Station, a seawater desalination plant on Camp Pendleton would require all-new intake and discharge facilities. Those facilities present key permitting issues for desalination projects, and the Water Authority's upcoming study will evaluate different configurations that are preferred by state regulators. The testing program will include the construction of pilot-scale facilities at Camp Pendleton to allow for side-by-side comparison of open-ocean and subsurface intake systems. The Water Authority study will focus on minimizing environmental impacts from operations, determining the variability in water quality from intake locations, addressing seasonal water quality changes such as algae blooms, and finding the best pre-treatment systems to improve performance of the reverse-osmosis membranes used to remove salt from seawater.

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