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Desalination Plant Whets Appetite of Thirsty County

Desalination Plant Whets Appetite of Thirsty County

BY LEE ZION

Staff Writer

The San Diego County Water Authority will discuss a proposal this week which could give the region access to a new source of fresh water , more than 18 billion gallons of water a year.

The water authority will meet Nov. 14 to look at a plan to build a $250 million desalination plant in Carlsbad. The facility would desalinate sea water, or remove the salt, producing 50 million gallons of fresh water a day.

That works out to 56,000 acre feet of fresh water annually, or enough to meet the water needs of almost 300,000 people. The plant could later be doubled in size, the need should arise in the future, said Peter MacLaggan, vice president and regional executive of Stamford, Conn.-based Poseidon Resources Corp.

Poseidon has developed, financed and invested in more than $2.5 billion of infrastructure projects since the company was founded in 1995, he said. The Carlsbad plant would be similar to a Poseidon facility in Huntington Beach, approved in September, and another under construction in Tampa Bay, Fla., which opens in March, MacLaggan said.

The cost of the water at the proposed Carlsbad facility will be $909 per acre foot. That figure includes the cost of amortizing construction costs and building the pipelines to connect the plant with the county system, he said.

This compares to about $400 per acre foot bought from the Metropolitan Water District of Southern California. However, that figure doesn’t take into account several other factors.

First, if the water-strapped San Diego were to develop a new source of water from any source other than desalination, that would cost about $650 per acre foot.

Meanwhile, the MWD has offered incentives of $250 per acre foot for desalination, lowering the cost of water from the proposed Carlsbad facility from $909 per acre foot to $659, similar to what it would cost to import a new source of water from anywhere else, MacLaggan said.

Also, desalination, converting sea water locally, helps the county avoid having to spend “several hundred million dollars” on pumps and pipelines to bring additional water over the mountains, he said.

The plant would use “reverse osmosis” technology, and San Diego County is one of the leading producers of the equipment used in reverse osmosis. Poseidon would work with one of its longtime suppliers, Hydranautics Corp., based in Oceanside, MacLaggan said.

Powering Up

The plant, which would take up about 3.2 acres, would be built on the roughly 100-acre grounds of an already existing electricity generating station in Carlsbad, the Encina facility owned by Cabrillo Power, he said.

This way, the desalination facility would be able to use an already existing intake for sea water, currently used for coolant at the power plant. The neighboring power plant would also supply the desalination facility with the juice it needs , a constant flow of 35 megawatts, or enough energy for 35,000 homes, MacLaggan said.

Since it takes two gallons of sea water to make one gallon of fresh water, 100 million gallons of sea water would be pumped into the plant every day. Of this amount, 50 million gallons would become drinking water, while the remainder would be discharged back into the ocean, using the Encina plant’s outfall, he said.

The water leaving the desalination facility would be twice as salty as regular sea water, but it would be mixed with millions of gallons of cooling water from Encina. Thus, the resulting flow, once discharged into the ocean, would increase salinity by no more than 1 percent, at a point 1,000 feet from shore, MacLaggan said.

Bob Yamada, a project manager with the County Water Authority, said earlier studies have shown that it would be technically and economically feasible to build such a project. Since it would be built on an already industrial site, it’s a compatible land use, while the nearby water intakes and power generation reduces infrastructure costs, he said.

However, the Nov. 14 vote would consider whether to move ahead with the project, and what shape it would take. So far, the board has raised some objections, including the fact that the cost of electricity , $281 for each acre foot of water desalinated , seems rather high, Yamada said.

The board would feel more confident about the proposal if it were allowed to shop the project around, introducing fair competition for service. Some board members have stated they should be involved in the project as a condition of approving it, he said.

If the water authority board approves the project, there are several other hurdles it must clear before it can be built. The project must then go before the California Coastal Commission, the state Water Resources Board and several other agencies, Yamada said.

MacLaggan said the Tampa Bay desalination facility faced strong opposition from Florida environmentalists, who worried about oxygen and saline content at the plant’s outflows. So far, however, the plant has not yet faced opposition here.

Carolyn Chase, a local environmentalist who publishes the San Diego Earth Times, gave tentative support to the project.

“It’s an interesting site, because it already has the power plant there now. And, therefore, there’s a large flow of millions of gallons of water a day that’s already being taken through that system and discharged,” she said. “If you can stick the desalination filtering system in between the plant and the outfall, the environmental impacts would be less than trying to install it some place new.”

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