Expert panel says subsurface pipes for Poseidon desalination plant too costly

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The fate of a proposed water desalination plant in Huntington Beach remains uncertain after a panel of experts has concluded that it would be too expensive to build it using intake pipes under the sea floor. That was the approach favored by the California Coastal Commission, whose approval is needed to begin construction. 

A report released Monday by the Independent Scientific Technical Advisory Panel found that although a subsurface intake system could be constructed to produce 50 million gallons a day, the economic viability is "highly uncertain" and faces financing risks that could keep the desalination plant from being built.

It is unclear if the firm that wants to build the plant, Poseidon Water, will try again to persuade the Coastal Commission to let it construct the facility with Poseidon's preferred intake system, open-ocean pipes situated above the sea floor. 

Poseidon says a desalination plant in Huntington Beach would produce 50 million gallons a day of drinking water for millions of people in the Orange County area.

Project planners for the facility have been trying since 2002 to obtain permits to build.

Environmentalists objected to an open-ocean intake system, arguing that marine life could be harmed as water is sucked into the pipes. They said they would rather see the plant built using subsurface pipes.

Echoing those concerns, the staff for the Coastal Commission recommended in 2013 that the panel approve the project only if Poseidon built it with subsurface pipes; in response, Poseidon withdrew its permit application pending the outcome of the feasibility study. 

The Commission and Poseidon then jointly selected the Technical Advisory Panel, which determined last year that two types of subsurface intake systems were technically feasible: Seabed and beach infiltration galleries. That was the first phase of the review.

The second phase was to determine if it was economically and environmentally feasible to use either a seabed or beach infiltration intake system.

In Monday's report, the Advisory Panel said it "reconsidered" the technical feasibility of a beach infiltration system, and concluded that it is "infeasible at the Huntington Beach location," in part because it would need to be substantially larger than first believed, and building it "would require many years ... due to construction constraints on a highly used public beach."

The panel went on to report that a seabed infiltration system "is not economically viable at the Huntington Beach location within a reasonable time frame, due to high capital costs and only modest reduction in annual operating costs."

The report projected that it would cost an annualized average of  $3,452 or $3,471 per acre foot during the plant's life cycle for desalinated potable water using a seabed infiltration system, depending on the construction method.

The Advisory Panel concluded that it is unlikely Poseidon Water would find an agency willing to pay that much for drinking water through 2033.

On the other hand, the expert panel determined that the open ocean intake system, as originally proposed by Poseidon Water, "may be economically feasible in the near future, depending on the outcome of negotiations with the Orange County Water District."

The Orange County Water District decided in May to enter into negotiations with Poseidon Water to buy the output of a desalination plant. The water district services more than 20 cities and water agencies.

"Under the current term sheet, OCWD might be willing to pay these water costs in 2018," the report said.

The release of the draft report begins a 24-day public comment period and also includes a public meeting scheduled for August 27 in Huntington Beach.

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