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County's first desalination plant ahead of schedule

The desalination plant is taking shape seaside in Carlsbad. Photo courtesy of Poseidon Water.

Poseidon Water, which is developing in Carlsbad what will be the largest seawater desalination plant in the Western Hemisphere, is contracted to have the plant running by late November 2015.

If the current pace of progress is maintained, the plant, expected to produce 50 million gallons of drinking water per day, could be operational up to three months ahead of time.

In May, Poseidon reached a "critical milestone," Senior Vice President Peter MacLaggan said, when it hit the project's 50 percent completion point. As of mid-July, the project stood 60 percent complete, and MacLaggan's conservative estimate places it at 65 percent by the beginning of September.

The construction teams of Israel-based IDE Technologies and Kiewit Shea Desalination, a joint venture of Kiewit Infrastructure West Co. and J.F. Shea Construction Co., are quickly transitioning from project tasks that are more civil works-related -- pouring concrete, digging trenches and laying pipe -- to the more mechanical construction activity.

By late July, items including high-pressure specialty seamless pipes were arriving on site and pumps were being installed and wired into place.

An existing electrical substation was equipped with two new transformers offsite to serve the power supply for the plant.

The four bundles of 6-inch-diameter cables that have been dropped in place traverse railroad tracks and continue through a tunnel into the plant's west side, where San Diego Gas & Electric meters are located.

MacLaggan said in mid-August that SDG&E was expected to initiate service to the meters before the end of the month. With the pace at which his contractor's are moving, MacLaggan said, the timing was just right.

"We're quickly getting to the point where some of this equipment's ready for testing," he said.

He attributes some of the accelerated progress to a relatively easy site remediation and demolition before vertical construction began.

The $922 million desalination plant is going up on a 6-acre corner of the Encina Power Station property. On the edge of Carlsbad’s Agua Hedionda Lagoon, the site will allow for a multipurpose use of space and resources -- the desalination facility is to be connected to the discharge channel of the seawater-cooled Encina Power Station in a couple of locations.

Early on, the plan to build next to a power station left MacLaggan not knowing what to expect. To his surprise, he said, there was remarkably less clean-up than expected.

"Our biggest fear on this job was with this being a 60-year-old power plant, you never know what's going to be underneath the ground," he said. "We had established a budget for what we expected to encounter in that regard. We were pleasantly surprised that we were able to get through the demolition phase and into construction phase … within our original budget estimates."

By the end of the year, MacLaggan said, he expects all the pumps and pipes to be installed and all the electrical connections to be made, allowing for water to start flowing through the plant.

The testing process at that point will start slowly, with only some water pumped uphill from the intake to pressure-test pipes and tanks.

"By March (2015), I think we'll have the sand filters operating, and in April we roll into the reverse osmosis system, and start testing the RO," he said.

That "commissioning phase" of testing will continue at the current pace into late June or early July next year, and then there will be 30 days of performance tests at full capacity.

MacLaggan cautioned, though, that such a timeline is no guarantee, but an estimate based on being ahead of schedule through now.

In the midst of a drought, any amount the project is ahead of schedule may be good news for project proponents who have long said it will make a sizeable dent in the region's dependence on imported water. On July 24, the San Diego County Water Authority approved enacting a Stage 2 Drought Alert through its Model Drought Response Ordinance, making mandatory what were water conservation recommendations in its Level 1 Drought Watch.

The Water Authority acted in response to the State Water Resources Control Board's vote to start enforcing on Aug. 1 certain landscaping-focused restrictions statewide.

Dana Friehauf, acting water resources manager for the Water Authority, said that the opening of the desalination plant could improve water resource outlooks across the state, not just in San Diego County. Some of the most severe water restrictions seen in the state have been averted in San Diego because of large investments in storage and conservation efforts by the Water Authority during the last decade.

"If we would have had the Carlsbad desalination plant online … northern areas of the state could potentially use what the county was no longer needing," Friehauf said.

The San Diego region’s largest water supplier, the Metropolitan Water District of Southern California, is expected to deliver approximately 1.1 million acre-feet of water from storage to meet demand in its service area this year, reducing its reserves by about half.

The effect of any potential reductions in MWD deliveries over the next couple of years could be moderated by the desalination plant.

But not everyone sees the plant through the same lens. Groups such as the Surfrider Foundation, the Coastal Environmental Rights Foundation and San Diego Coastkeeper are opposed to particular aspects of the plant coming online.

Sara Kent, program director for CERF, said the plant will be energy intensive and produce too many greenhouse gases.

MacLaggan said the expected connected hourly load at the plant will be 35 megawatt-hours. Since much of the electricity brought in by SDG&E will come from fossil fuel sources, Poseidon found ways to offset the effects, MacLaggan said.

"In California, we cannot go out and directly buy renewables," he said, "but we can do things to offset the carbon that is embedded in the energy provided by SDG&E.”

Recapturing carbon dioxide for use in its process is one of those offsetting measures taken, MacLaggan said.

According to Poseidon's Energy Minimization and Greenhouse Gas Reduction Plan, approximately 2,100 tons of carbon dioxide per year are planned to be used at the plant for post-treatment of water produced by the reverse osmosis system.

To the extent that it's reasonably available, Poseidon intends to get the carbon dioxide from a recovery operation, MacLaggan said.

Additionally, the plant's pressure exchanger-based energy recovery system allows recovery and reuse of 33.9 percent of the energy associated with the reverse osmosis process, the energy plan notes.

MacLaggan said Poseidon has also partnered with the California Department of Parks and Recreation to commit to planting trees in the Cuyamaca Rancho State Park to reforest areas burned out by the 2003 wildfires.

The developer is also required to offset its intake impacts by creating a 66-acre tidal wetland in the South Bay.

"Wetlands are known to sequester carbon as well, so if we can demonstrate that we successfully sequester carbon in the wetlands, we can get credit for that as well," MacLaggan said. "And then we'll take the balance of our energy footprint from SDG&E," which he said will vary year to year depending on where SDG&E procures its energy from.

"The expectation is that there will still be about 16,000 tons of net carbon in our energy footprint, and so we're going to go to in the marketplace and either purchase on an annual basis renewable energy credits or carbon offsets from the state of California to render our carbon footprint neutral,” he said.

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