As the State of California faces a record drought, ocean desalination has been highlighted as a potentially more reliable alternative to imported water.
Following the California Coastal Commission’s (CCC) unanimous vote to deny permits for the Brookfield-Poseidon Desalination plant in Huntington Beach last month, the South Coast Water District (SCWD) is working to obtain all major permits for its own desalination plant near Doheny by the end of the year.
The local water district is looking to produce up to five million gallons of potable drinking water a day by 2027 through its proposed Doheny Ocean Desalination project. The Poseidon plant would have produced up to 50 million gallons of potable water daily.
“We know that we have major water problems in California and it’s going to take every tool in the toolbox, including intelligent desalination to address those,” California Coastal Commission Chair Donne Brownsey said during the May 12 hearing. “While this may be a study of an unsuccessful end, I hope that it is a beginning of success for these kinds of projects with consensus in the future.”
During the CCC hearing, opponents of the project cited an increase in cost for water ratepayers and harm to marine life while proponents noted the ongoing severe drought and need for new water sources.
The Commission’s denial of the Huntington Beach desal plant leaves a hole in the county’s water supply portfolio, which the Doheny plant could fill, according to Kevin Thomas, a representative of Kimley Horn—the district’s engineering consultant on the project.
Thomas explained that the Poseidon plant has been identified as part of the Orange County Water Supply portfolio for over 15 years.
“There needs to be new water supplies developed and (the Doheny Ocean Desalination Plant), I think, would be the first truly ocean plan compliant desalination facility built in the state with the subsurface intake, the comingled brine. I think it’s the kind of project that the Coastal Commission would rather see happen,” Thomas said.
One of the biggest differences between the two plants is the difference in their size and capacity, said Mark Donovan, desalination program manager and representative of GHD Inc. The Poseidon plant has a production capacity 10 times the size of the Doheny plant, Donovan said.
There are also notable differences in the infrastructure of the Huntington Beach desalination plant compared to the Doheny plant.
The Poseidon plant intended to use existing infrastructure from the AES Huntington Beach Energy pipelines for intake and outfall. Donovan explained that the old power plant used a “once-through cooling system” to bring seawater in and sent it back out to the ocean.
Poseidon’s plans were to use that existing infrastructure while adding a fine, one-millimeter wedge wire screen into the ocean end of the intake tunnel to prevent marine life from being impacted during intake, Donovan said.
The Doheny Desalination plant would instead use a subsurface slant well when water is drawn into the desalination plant from below the ocean floor.
“Subsurface intake is actually the preferred method in the ocean plan for getting the seawater to the plant because that way you’re avoiding any impacts to marine life, you’re not pulling organisms through the screen to the plant; fish aren’t getting trapped or impinged against the screen that’s out in the ocean,” Donovan said. “None of that happens with a subsurface intake.”
California Ocean Plan states that “studies are prepared showing there is no predicable entrainment, impingement or construction-related marine life mortality” with the use of subsurface intake.
In discharging the salty waste produced as a result of the desalination, Donovan explained that the Doheny plant will co-mingle it’s brine with wastewater.
“We will be blending ours with an existing wastewater ocean outfall, which is also the California Ocean Plan preferred method of discharging brine back into the ocean from the desal plant,” Donovan said.
Poseidon’s plant, however, proposed using an existing outfall tunnel and diffusers to spread the briny waste rabidly out into the ocean.
According to the California Coastal Commission’s staff report recommending the denial of Poseidon’s plans for the desal plant, the high speed of the diffusers could kill marine life. However, the diffusers are needed to prevent a concentration of extremely salty water from sinking to the seafloor and creating “a high salinity ‘dead zone’ around the outfall.”
“The facility, in total, would kill marine life in about 100 billion gallons of seawater per year, resulting in substantial losses of marine ecosystem productivity and reduced water quality, all of which would require significant mitigation,” the staff report said.
The Doheny plant would also require less infrastructure to transport the potable water to neighboring cities as a major regional water transmission line crosses the site.
“That’s a major benefit of a potential regional project, and that pipeline easily serves, for example, San Clemente, San Juan Capistrano, and of course, our area and other areas in the proximity are served by that pipeline,” South Coast Water District General Manager Rick Shintaku said.
The Doheny plant is also roughly 1,500 feet from the shoreline, Thomas said.
“All the infrastructure needed to convey the water is right at the desalination facility site, so there’s not the miles and miles and miles of new conveyance pipeline that have to be built, which is the case with Huntington Beach,” Thomas said.
Since SCWD is a public water agency, whereas Brookfield-Poseidon was a private developer, the agency is able to receive grant funds and lower interest loans.
“We’ve been very fortunate in that we’ve received a significant amount of grant money from both the State of California and also the federal government, both EPA and U.S. Bureau of Reclamation,” Donovan said. “So, we’ve received over $30 million in grant money, which helps drive that overall cost of water down, wherein Poseidon’s case, they weren’t eligible for such grant programs in Huntington Beach.”
SCWD is not yet scheduled for a permit hearing, but it’s hoping to be scheduled for the fall. Poseidon’s hearing brought up items that SCWD is making sure to address, Shintaku said.
“There were certain items that were brought up that we need to make sure that we’re cognizant of and making sure we’re responding accordingly to that,” Shintaku said. “In terms of how our permit hearing will go, we think we’re checking off the right boxes.”
South Coast Water District hopes to have major permits for the Doheny Desalination plant by the fall, and hopes to have a State Lands Lease agreement by December of this year, Donovan said.
Shintaku added that the SCWD is currently going through a partnership education process in addition to going through permitting. SCWD is in the process of enlisting partners which would make the project more affordable for ratepayers, Shintaku explained.
“If we’re successful in the State Lands Commission lease at the end of the calendar year, in parallel, we’ll also be developing a design, build, operate, maintain contract that we would be using to bid out the work to the successful team,” Shintaku said.
After the permitting process, Shintaku explained that the SCWD board would need to decide whether to move forward with the project.
“This project isn’t fully greenlighted yet until we get through the permitting phase and our board makes a decision on how and if they want to move forward with this project, and that should come, in theory, in the next calendar year,” Shintaku said.
If all goes to plan, SCWD hopes to have the Doheny Ocean Desalination plant operating by 2027.