Subsurface Intakes Feasible

Panel of Experts and Plant Builder Poseidon Water Concluded that Two Types of Systems — Seabed and Beach Intakes for Proposed Desalination Plant

A study regarding a controversial proposed desalination plant in Huntington Beach determined that subsurface intakes are technically feasible for the project.

A panel of experts selected by the California Coastal Commission and plant builder Poseidon Water concluded that two types of systems — seabed and beach intakes — are possible to build at the proposed site, according to a draft report. The desalination facility would be built at the AES natural gas-powered electricity plant off Pacific Coast Highway at Newland Street.

The Orange County Water District, which covers Costa Mesa, Newport Beach, Huntington Beach and Fountain Valley, decided in June to pay a consultant to study the cost of buying water from the Poseidon plant.

There has been talk of the desalination plant using pipes under Costa Mesa to distribute water to water districts. However, Poseidon would need proof of interest from Costa Mesa, Huntington Beach and AES for that to happen.

The intake study, organized by Concur Inc., a Berkeley-based firm that specializes in complex environmental issues, analyzed nine different subsurface methods over several months this summer.

Since the report is a draft, changes could still be made, said Concur principal Scott McCreary, who oversaw the study. The final draft is expected to be completed this week, he said.

The report will complete one of two stages of the analysis of subsurface intakes. The second part will look into economic feasibility and environmental effects, McCreary said.

Once all aspects of the study are finalized, it will be brought before the Coastal Commission when Poseidon resubmits its application to build the plant.

Seabed infiltration galleries — a method in which intake pipes to collect seawater are placed under the ocean floor — can withstand natural events such as earthquakes and can be built off Huntington's shore, according to the report.

Beach galleries are similar but are constructed closer to shore.

Since subsurface intake pipes are under the surf zone, the breaking waves and sand would act as a self-cleaning filter for the plant, according to the report.

However, the panel said both types of subsurface intakes would involve complex engineering and could have a negative impact on the beach during construction.

"We're very encouraged by the conclusions, findings and recommendations, and we'll see what happens when the panel finalizes," said Scott Maloni, vice president of Poseidon.

Though his company has been pushing for open-water intakes, in which pipes are placed in the water above the sea floor, Maloni said subsurface intakes would be considered should they be technically and economically feasible. Open-water intakes would use the cooling pipes from the AES power plant.

Joe Geever, a consultant for the Surfrider Foundation, said he and other desalination proponents are glad that a report on subsurface intakes has been done.

"We've been requesting this for over 10 years," he said. "We finally got a report that indicates that subsurface intakes are technically feasible, which is what we suspected all along."

Other methods studied included vertical wells, which take in water directly underneath the well station. That method was found to be infeasible because it could draw water from the Orange County groundwater basin, according to the report. Additionally, it was estimated that more than 200 wells would be needed to draw in about 127 million gallons of seawater per day.

Source: Huntington Beach Independent

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• Desalination
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