Carlsbad plant brings ocean water to your tap
Jennifer Jones held out a plastic cup of water to a visitor.
The water was crystal clear and tasted fresh and pure, as if it had been poured from a bottle of spring water. There was nothing to suggest that as recently as one hour earlier, that water had been pulled from the ocean by powerful pumps.
Jones, a spokeswoman for Poseidon Water, was taking a reporter on a tour of the new seawater desalination plant on the Carlsbad coast, which officially went online Dec. 23 after a 15-year planning, permitting, design and construction process. The $800 million plant is expected to provide between 7 and 10 percent of San Diego County’s drinking water for at least the next 30 years.
The sole customer of the plant, which was developed by Poseidon and is now being operated under contract by an Israeli company, is the San Diego County Water Authority, the region’s water wholesaler. The water authority in turn supplies its member agencies, such as the Olivenhain Municipal Water District, San Dieguito Water District, Santa Fe Irrigation District and Carlsbad Water District.
The Carlsbad desalination plant is the only facility of its kind in the Western Hemisphere, and one of only two in the United States (the second is in Tampa, Florida). It is designed to produce about 50 million gallons of drinking water per day, and, a month after its launch, local water officials are pleased with the results
“The plant is producing water as advertised, and we are reaping the benefits of a new, drought-proof, reliable water supply, that our region is going to rely upon for decades to come,” said Bob Yamada, director of water resources with the water authority, who has been working on the project for 15 years.
“It couldn’t be more satisfying to see this plant up and operating in a reliable fashion,” he said.
The plant was dedicated on Dec. 14 in a ceremony attended by public officials from across San Diego County. Santa Fe general manager Mike Bardin was one of the attendees, and he said the event marked a historic day for both San Diego and California.
“We’re very pleased that it came on line, we think it’s a great success,” said Bardin. “Having a viable desalination plant will lead the way for others in California.”
Santa Fe has long supported the project, and was one of nine local water agencies to sign a contract to purchase water from the plant, said Bardin. However, it was later decided to spread the cost of the plant across the entire region, and the water authority took over as the direct purchaser of the plant’s output on behalf of its member agencies under a 30-year purchase contract. Support from agencies such as Santa Fe kept the project going during the lengthy permitting process, Bardin said.
The project included construction of a 10-mile pipeline, at a cost of $200 million, from the Carlsbad plant to the water authority aqueduct. The water authority blends the desalinated water with water obtained from other sources.
While the drinking water produced by the desalination plant does provide a reliable supply, impervious to the drought that has plagued California for the past four or five years, it does not come cheap.
Under its contract with Poseidon, the water authority pays between $2,131 and $2,367 per acre-foot of water, which is 325,900 gallons, or enough to supply two families of four for a year. In contrast, the water authority pays $624 per acre-foot, adjusted annually for inflation, for water it buys from Imperial Valley under a water-transfer agreement. The water authority will pay $942 per acre-foot in 2016 for water it purchases from the Metropolitan Water District of Southern California, according to figures supplied by the agency.
In 2016, the water authority will spend about $110 million on water from the desalination plant, said Yamada.
Officials expect the price of the desalinated water to come more in line with the cost from other sources in the future, because the price of imported water will rise faster than that of the water from the Carlsbad plant, said water authority spokesman James Palen.
The Carlsbad plant puts ocean water through a three-step purification process before it is piped into the water authority’s supply line. First, said Jones, the Poseidon spokeswoman, the water is pumped through layers of anthracite, sand and gravel to remove large particles. Next, it is filtered to remove smaller impurities.
Finally, said Jones, the water enters what is considered the heart of the plant — the reverse osmosis room. Banks of thousands of stacked tubes contain reverse osmosis membranes. The seawater is forced through the tubes at high pressure, and tiny holes in the membranes allow water molecules to pass, but block larger salt particles. The purified water goes on toward the plant’s outflow pipe, while water containing concentrated salt is mixed with seawater and pumped back into the ocean.
Before the water is sent on, minerals, chlorine and fluoride are added, Jones said.
The water authority is satisfied of the quality of the drinking water produced by the plant, said Yamada.
“There is rigorous monitoring that goes on every day, minute by minute and hour by hour, to ensure that the plant is producing a consistent water quality,” he said.
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