Los Angeles taps contaminated aquifers at Superfund sites to boost drinking water supplies

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Los Angeles is nearly finished with a $600 million project in the east San Fernando Valley that will turn contaminated groundwater from Superfund sites into drinking water for as many as 261,000 households annually.

The three new treatment facilities, expected to become operational in the second half of 2023, will produce up to 87,000 acre feet, or roughly 28 billion gallons, of drinkable water during a typical year, according to the Los Angeles Department of Water and Power.

The project is a major step toward achieving the city’s goal of obtaining 70% of its water from local sources by 2035, a move that will rein in the city’s reliance on imports. Today, about 90% of the water consumed by Angelenos comes from elsewhere.

“When we had full access to our groundwater wells historically, we were able to rely on groundwater for up to 23% of the city’s water supply,” said Evelyn Cortez-Davis, LADWP’s director of water engineering and technical services. “In recent years, it’s been closer to 10%.”

The local supply dropped to as low as 4.2% during the drought in 2017-18, the city’s data showed. It hasn’t been above 20% since 1999.

Two of the new facilities are located in North Hollywood, while the largest, which will treat about half of the water, is in the Tujunga Spreading Grounds in Pacoima.

The future of water

Today, L.A. uses about as much water as it did in the 1970s, though it has about a million more people, Cortez-Davis said. Yet, conservation alone isn’t enough to ensure future water reliability, she said.

To meet its lofty 70% goal, the city is developing a slew of projects that will optimize stormwater collection, maximize the use of recycled water and reopen wells, like those in the San Fernando Valley, that have been shuttered for decades due to contamination. The San Fernando Basin is the largest aquifer in LADWP’s footprint, yet more than two-thirds of its 115 water wells aren’t in use due to groundwater pollution dating as far back as the 1940s.

The San Fernando Valley Superfund, a federal classification placed on the most polluted sites in the country, is made up of four segments and roughly stretches from Pacoima to Burbank and Glendale. Those two neighboring cities already are operating treatment facilities on their portions and can pump 7 million to 9 million gallons of water from their portions of the Superfund sites each day, according to the EPA.

Source of contamination

Much of the contamination in the basin comes from solvents and other chemicals that seeped into the ground decades ago when the area was a haven for the aerospace industry and other manufacturers. For years, LADWP and the EPA have tried to track down the responsible parties. Some, such as Honeywell and Lockheed, have settled with the city already. Others have been more difficult to identify, in part due to the length of time that has passed.

The EPA looked at more than 400 different facilities to try to determine who was responsible.

As part of their settlements, Honeywell and Lockheed have agreed to fund the treatment of up to 6.3 billion gallons of water each year, which LADWP estimates could save the city as much as $800 million over the length of the agreement.

But rather than wait years to track down all of the culprits, LADWP has opted to move forward with building the treatment facilities proactively, Cortez-Davis said. That decision won’t prevent the city from seeking reimbursement from any responsible parties identified in the future either, she said.

“It’s in our best interests to make sure this remediation happens sooner than later,” she said.

The region’s stubborn drought and climate change have made imported water less reliable, and the city wants the greater control it can only get from managing the water sources itself, she said.

That shift won’t come cheap. About half of $600 million price tag for the three facilities is funded by Proposition 1, a $7.5 billion water bond measure passed by California voters in 2014. The other half will be paid by ratepayers, Cortez-Davis said.

“We have these plans in motion that require significant investment, but we’re talking about investing in the future of long-term water reliability,” she said.

This type of work is crucial to reclaiming local water sources, according to the state. Proposition 1 earmarked $670 million in grants, administered by the State Water Resources Board, specifically for projects that prevent and clean up groundwater contamination.

“With the region’s water supply increasingly threatened by drought conditions and climate change, cleaning up our aquifers is critical to protecting our drinking water and other beneficial uses,” said Norma Camacho, chair of the Los Angeles Regional Water Quality Control Board, in a statement. “Our board is aggressively taking steps to remediate contaminated sites and expand our water resilience portfolio.”

A LADWP field worker is installing sleeves for the lamps on the UV reactors. The sleeves are clear tubes that protect the lamps from water. There are 6 UV reactors at Tujunga with 384 lamps per reactor. (Courtesy of LADWP)
An LADWP field worker installs sleeves for the lamps on the UV reactors. The sleeves are clear tubes that protect the lamps from water. There are six UV reactors at the Tujunga plant, with 384 lamps per reactor. (Courtesy of LADWP) 

How the water is treated

The chemicals identified in the basin include trichloroethylene, perchloroethylene and 1,4-Dioxane, according to the EPA and LADWP. To remove the contaminants, the pumped water will be mixed with hydrogen peroxide, filtered to excise sediment and then passed through ultraviolet reactors that break down the compounds by exposing them to UV lamps.

The water then travels through a granular activated carbon filtration system — imagine a giant Brita filter — to remove excess hydrogen peroxide and any other leftovers. Once the treatment is finished, the water finally goes through the typical disinfection and fluoridation process used on all of the city’s drinking water.

Other Superfund sites

While the idea of getting drinking water from a polluted Superfund site might sound intimidating, similar projects have existed for decades elsewhere in Southern California.

A large swath of the San Gabriel Valley sits on top of four Superfund sites that contain roughly 44 square miles of contaminated groundwater.

Since 2001, water utilities in that area have set up 14 different groundwater treatment systems that pump and treat about 56 million gallons of drinking water per day, according to the EPA. Another project in the design phase is expected to add an additional 2.5 million gallons of drinking water to the total.

The various utilities serving the San Gabriel Valley have treated a total of more than 200 billion gallons of contaminated water and removed more than 100,000 pounds of contaminants, according to a fact sheet published by the EPA. The total cost was at nearly $600 million as of May 2021.



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