Largest U.S. Desalination Plant on San Diego's Drawing Board

Producing up to 150 million gallons per day, the project will cost more than $2 billion, if built to full capacity. It could supply enough additional water to meet the needs of 24 water agencies, including the city of San Diego, that buy water wholesale from the county authority, said Water Resources Manager Bob Yamada.

A summary feasibility study presented to the board's Water Planning Committee did not include a completion date. If the full board approves the project, construction could not begin until environmental studies are conducted and a long list of state and federal permits and agreements are obtained, a process that could take years.

Committee members discussed the proposal, but took no action.

Desalination - removing salt from seawater - is seen by water experts as one tool in a catalog of options for ensuring an adequate water supply to growing areas. Other proposals include conservation efforts and recycling of sewage and other non-potable water supplies.

Drought and reduced water deliveries from northern California are forcing water agencies throughout southern California to seek ways to conserve and augment supplies.

The Pacific Ocean at Camp Pendleton Marine Base (Photo by Kevin)

But seawater desalination projects can be controversial because huge water intake lines and brine discharged back into the ocean damage the environment and the process of removing salt from sea water uses large amounts of energy.

Those issues and others, including costs to consumers, are part of the permit process.

At full capacity, the proposed reverse osmosis plant would be three times larger than the $300 million Poseidon Resources plant in nearby Carlsbad, according to the Water Authority's summary feasibility study.

At 50 million gallons a day, the Poseidon project is the largest currently planned for the United States, expected to meet the needs of 300,000 residents. Poseidon received its final government approval this week. It is scheduled to begin construction in 2009 and is supposed to be operational by 2012.

Yamada said if the Camp Pendleton proposal is built to its 150 gallon per day capacity, "as far as I know, it would be, by far, the largest desal project in the country."

The San Diego County Water Authority's proposal for Camp Pendleton is intended to provide water in conjunction with the Poseidon project, not compete with it, Yamada said.

The feasibility study outlined a project that could be built in increments, with the first stage possibly as small as 50 million gallons a day at a cost of $1.25 billion. If the first stage is 100 million gallons per day, that cost was estimated at $1.91 billion. The final 50 million gallon section could be added later.

Initially, the San Diego County Water Authority looked at the Southern California Edison nuclear power plant on the coast at San Onofre as a possible site for its desalination plant. But, according to the feasibility study, Edison had concerns the desalination project would interfere with its future energy development plans.

Now the Water Authority, working with Camp Pendleton staff, is considering either of two sites along Interstate 5 on the southwest edge of the huge Marine base.

A formal agreement would have to be reached with the Marines for the desalination plant to be built on the base.

The feasibility report says benefits to Camp Pendleton include increasing the reliability of the base water supply, improving the quality of its water, providing a wastewater disposal option and possibly offering the base a source of emergency power.

Power to run the desalination plant would come either from traditional power lines or from a natural gas power source built specifically for the project.

To move forward, the San Diego County Water Authority must approve funds in the 2010-2011 budget to continue to pay for planning, including technical studies and an Environmental Impact Report. The Water Authority and Camp Pendleton also must reach an agreement that allows site and environmental studies and defines the roles and responsibilities of each side.

The world's largest desalination plant, which produces 211 million gallons a day, opened last month in Jubail, Saudi Arabia.

{This report is republished courtesy WaterWebster.org}

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