By Jay Landers
Located in semiarid Southern California, the city of Los Angeles relies heavily on water supplies imported long distances from Northern California, the Sierra Nevada, and the Colorado River. Although Los Angeles has significant local groundwater supplies, the city has had to reduce its use of this valuable resource because of contamination from industrial sources dating back more than half a century.
Looking to regain access to more of its groundwater supplies, the Los Angeles Department of Water and Power is nearing completion of three long-planned facilities that will be used to remediate subterranean contamination in the San Fernando Basin. Scheduled to begin operations in 2024, the treatment facilities will enable Los Angeles to more than double the volume of groundwater that it uses for its drinking water supply, decreasing its reliance on imported water and increasing system resilience in the event of a destructive earthquake.
Groundwater contamination in the San Fernando Basin began in the 1940s, when commercial companies and other heavy industries are believed to have improperly handled and stored large volumes of hazardous volatile organic compounds, says Ofelia Rubio, P.E., the manager of project and construction management for the LADWP. The contaminants then entered the environment and found their way to the underlying aquifer.
Once in the groundwater, the contamination spread considerably. “The contaminated plume is approximately 12 mi by 2 mi,” Rubio says. The main contaminants include trichloroethylene, perchloroethylene — which is also known as tetrachloroethylene — and 1,4-dioxane, she notes.
The compounds have been linked to various adverse health effects in humans, including certain types of cancer and other diseases, according to overviews on trichloroethylene, perchloroethylene, and 1,4-dioxane prepared by the Agency for Toxic Substances and Disease Registry within the U.S. Department of Health and Human Services.
Because of concerns about the widespread groundwater contamination, the U.S. Environmental Protection Agency added four large sites within the San Fernando Basin to the National Priorities List, commonly known as the Superfund program, in 1986. The three groundwater treatment facilities under development by Los Angeles are in or near what the EPA named the Area 1 San Fernando Valley Superfund site. Area 1 is primarily in North Hollywood and Burbank.
Doubling groundwater use
Currently, Los Angeles is operating only 41 of its 115 groundwater wells in the San Fernando Basin, Rubio says. Combined, the operational wells provide approximately 8% of the city’s water supply, she says. Once operations begin at the three groundwater treatment facilities next year, they “have the potential to provide up to about 23% of the city’s supply,” Rubio notes.
Following several years of studies to characterize the contamination plume and determine optimal treatment methods, the LADWP in 2015 began to conduct remedial investigation and feasibility studies and remedial designs for three projects known as “response actions.” Each of the response actions will address groundwater contamination near a major city well field in the San Fernando Basin.
For the three response actions, the consulting engineering firm Hazen and Sawyer has served as the owner’s agent and lead consultant as part of a team that includes the consulting engineering firms Arcadis and the Worley Group. The team developed the feasibility studies and conceptual designs for the three facilities.
All three projects involve groundwater pump-and-treat systems employing an ultraviolet advanced oxidation process using UV light and hydrogen peroxide. “It's a pretty advanced system for breaking down contaminants,” Rubio says. Other treatment steps include sand separators, cartridge filters, and granular activated carbon units.
Following treatment, the groundwater will enter the city’s distribution system, Rubio says. “It meets all drinking water standards, and then it's combined with the city's other water supplies and distributed,” she says.
The first, and smallest, of the three facilities is known as the North Hollywood West Response Action, so named because it will treat contamination within the city’s North Hollywood West Well Field. Designed by the team led by Hazen and Sawyer, the facility has a treatment capacity of 28.4 cfs and includes four UV reactors, each of which has 192 lamps, and 18 GAC vessels.
Construction on the North Hollywood West facility, which began in 2017, was conducted by the LADWP. The facility is scheduled to begin operations in early 2024, Rubio says.
The second facility, known as the North Hollywood Central Response Action, will remediate contamination within the Rinaldi-Toluca Well Field. Located within the city’s North Hollywood Pump Station Complex, the facility will have a treatment capacity of 38.2 cfs. The North Hollywood Central facility features four UV reactors, each of which is equipped with 384 lamps, and 18 GAC vessels.
The third, and largest, facility — known as the Tujunga Well Field Response Action — will address groundwater pollution in the city’s Tujunga Well Field. The facility is adjacent to the Tujunga Spreading Grounds, a 150-acre area used to capture stormwater and recharge it into the groundwater system of the San Fernando Basin. Having a treatment capacity of 76.5 cfs, the Tujunga treatment facility includes six UV reactors, each of which has 384 lamps, and 36 GAC vessels.
The North Hollywood Central and Tujunga facilities are being delivered via a progressive design-build contract by a team comprising the construction firm Kiewit Infrastructure West Co. and the consulting design firm Stantec. Construction began on the North Hollywood Central and Tujunga treatment facilities in late 2020. Both facilities are expected to be completed by the summer, Rubio says. (Stantec was unable to respond in time to comment on this story.)
The LADWP will operate all three of the treatment facilities, a setup that is expected to last at least two decades if not longer, Rubio says.
All told, design and construction of the three groundwater treatment facilities is expected to cost about $587 million, Rubio says. Of this amount, the North Hollywood Central and Tujunga facilities total approximately $495 million, while the North Hollywood West facility cost about $92 million.
More than half the project financing has taken the form of grant funding from the California Department of Water Resources. The DWR awarded the LADWP $308 million in funding authorized by Proposition 1, which California voters passed in 2014 to help pay for integrated regional water management projects. The remainder of the project costs are coming from the LADWP budget, Rubio says.
Separately, the aerospace giant Honeywell is constructing groundwater treatment facilities in the San Fernando Basin under the terms of a 2019 settlement with the LADWP. Upon completion, the facilities will be operated by the LADWP, while Honeywell will pay operations costs, Rubio says.
Along with boosting the use of local water supplies, the three groundwater remediation facilities will aid the city’s efforts to fortify its drinking water system against long-term disruption from a major seismic event.
In the event of an earthquake, the city’s access to some or all its imported water supplies could be interrupted as a result of damage to the extensive system of pipelines, tunnels, and related infrastructure used to convey water to Los Angeles. “Certainly, being able to depend on local supplies will make us more resilient,” Rubio says.
Meanwhile, the LADWP is investigating the possibility of conducting more response actions to treat contaminated groundwater in the San Fernando Basin. “There are a number of other projects where we are looking at different sites, looking at whether or not it would be beneficial for us to construct more groundwater wells,” Rubio says. “Our intent is to be considerably more self-reliant on local water,” she notes.
Long term, Los Angeles intends to ramp up groundwater recharge efforts significantly. As part of an estimated $16.9 billion project known as Operation Next, the LADWP and LA Sanitation and Environment — the city agency responsible for solid waste, clean water, and watershed protection — plan to inject underground effluent treated by the city’s Hyperion Water Reclamation Plant, after it has been revamped to provide advanced water treatment. Following injection, the treated water then will be available as part of a planned program of indirect potable reuse.
This article is published by Civil Engineering Online.