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Project Backgrounder - Overview of NASA’s Comprehensive Groundwater Cleanup Plan at and in the Vicinity of the Jet Propulsion Laboratory (JPL)

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A Commitment to Safeguard Area Drinking Water and Restore Water Resources

NASA is committed to cleaning up groundwater affected by chemicals associated with historic and long-discontinued waste disposal practices at the Jet Propulsion Laboratory (JPL). NASA is cleaning up the site under the Federal Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), commonly known as Superfund. The groundwater chemicals being addressed by NASA are volatile organic compounds (VOCs) and the chemical compound perchlorate. While NASA takes the lead for environmental investigations and cleanup activities associated with JPL, federal and California regulatory agencies provide oversight, including the:

  • U.S. Environmental Protection Agency (EPA), 
  • California Department of Toxic Substances Control (DTSC), and 
  • Regional Water Quality Control Board (RWQCB), Los Angeles Region

A Signed Final Cleanup Plan 

The groundwater cleanup program achieved a major milestone early in 2018. NASA and the regulatory agencies approved and signed a final cleanup plan referred to as the final Record of Decision (ROD). The parties agreed that continuing the operation of the three groundwater treatment plants [see below] at and near JPL is “the best approach to reaching the cleanup goals and maintain protection of human health and the environment.” NASA prepared a fact sheet summarizing the investigations and remedial actions that led to approval of the ROD.

Three NASA-Funded Groundwater Treatment Plants Will Continue Under the Final Plan

  • One of the NASA-funded groundwater treatment plants is located on JPL property and has been successfully removing groundwater chemicals from the source area since January 2005.
  • Another plant is removing groundwater chemicals from the farthest reaches of the area affected by the chemicals – at wells operated in Altadena by the Lincoln Avenue Water Company (LAWC). 
  • A third plant on City of Pasadena-owned property adjacent to the Windsor Reservoir— the Monk Hill Treatment System (MHTS)—is providing groundwater cleanup in the area between the source of the chemicals and the farthest reaches. Pasadena Water & Power (PWP) has been able to re-open previously closed water production wells located in the Arroyo Seco and serve treated water from those wells to its customers. 

The combination of these three treatment plants working together will complete the cleanup over the next 10-15 years.

JPL Site Cleanup Activities: A Brief History

Soil Cleanup

Even before the groundwater treatment plants were operating,  NASA used a technology called soil vapor extraction (SVE) to remove 230 pounds of carbon tetrachloride and 30 pounds of trichloroethylene (TCE) from the dry soil directly beneath JPL. By removing this source of chemicals, NASA eliminated further chemical movement from the soil into the aquifer hundreds of feet below the ground surface.  This SVE was completed in 2007.

Groundwater Treatment at the Source Area

NASA’s source area groundwater treatment system, located in the north-central section of the 150-acre JPL complex, focuses on an eight-acre by 100-foot-thick portion of the aquifer deep beneath the ground surface.

  • A liquid-phase granular activated carbon (LGAC) technology is being used at the JPL source area to trap dissolved VOCs for subsequent disposal at licensed off-site facilities.
  • To break down and eliminate perchlorate from groundwater beneath JPL – from system startup in January 2005 to late 2019 – the system originally used a fluidized-bed reactor system with naturally-occurring organisms. With considerably lower levels of perchlorate in the source area groundwater by 2019, a new ion exchange perchlorate-removal technology and a new groundwater extraction well were installed and became operational in 2020. The new ion exchange technology is proven to be more effective than the previous technology at treating low levels of perchlorate

By the middle of 2022, the total amount of unwanted chemicals in groundwater beneath JPL has been reduced by more than 98 percent. The system has removed more than 2,137 lbs. of perchlorate and more than 49 lbs. of VOCs since startup.

While chemical removal has been significant, cleanup needs to continue. Reduced groundwater chemical levels are still above the stringent cleanup goals set forth in the final cleanup plan outlined in the 2018 Record of Decision. Continued operation of the systems to achieve those cleanup goals is expected to take another five to ten years. This is typical in groundwater remediation because chemical removal becomes more difficult as concentrations decrease. It takes a long time to flush enough water through the aquifer to achieve the cleanup goals in the ROD.

NASA’s strategy to target chemicals at the source area is helping to:

  • Remove chemicals from groundwater at the source area, where the highest levels of the chemicals are found, and
  • Reduce migration of chemicals to offsite groundwater beneath areas near JPL.

Groundwater Treatment with Lincoln Avenue Water Company

Since 1992, the Lincoln Avenue Water Company (LAWC) has operated a NASA-funded treatment plant, removing VOCs from LAWC’s water production wells in Altadena. In 2004, NASA funded the expansion of that plant to remove perchlorate from the groundwater, enabling LAWC to provide its customers with a continuous supply of drinking water that meets all state and federal clean drinking water standards. NASA also funded construction of a third drinking water well for LAWC, which was put into operation in late 2017. <

Groundwater is treated by the LAWC plant at a rate of up to 2,000 gallons per minute (gpm). The system uses an ion exchange perchlorate-removal technology, while VOCs are removed from the groundwater with a liquid-phase granular activated carbon (LGAC) technology. By the middle of 2022, the system had removed more than 1,427 lbs. of perchlorate and more than 343 lbs. of VOCs. In all, since 2004, the three wells and associated groundwater treatment have reduced total chemical concentrations in the LAWC groundwater by nearly 85 percent.

Groundwater Treatment with City of Pasadena

In the spring of 2011, the City of Pasadena began operating the NASA-funded Monk Hill Treatment System, or MHTS, near four previously closed water production wells located in the Arroyo Seco. The plant, with an operating capacity of 7,000 gallons per minute, is removing perchlorate from groundwater using ion exchange technology and VOCs using LGAC technology. By mid-2022 and since startup, the system had removed more than 1,405 lbs. of perchlorate and more than 227 lbs. of VOCs. Total chemical levels in groundwater extracted by the MHTS have been reduced by more than 90 percent. 

New Well Construction Planned for MHTS

With NASA funding and technical support, Pasadena Water and Power (PWP) is planning to construct a new drinking water well located in the northern portion of the Arroyo Seco. The new well would help increase removal of targeted chemicals by an estimated 40 percent and would significantly reduce the time needed to clean up the aquifer. Groundwater from the new well would be piped to and treated at the Windsor Avenue plant along with water from the four existing wells. This new well would be strategically located to capture chemicals originating from the JPL site. 

Groundwater Treatment Technologies' Effectiveness

Liquid granular activated carbon (LGAC) and ion exchange (IX) are two treatment technologies that have been shown to be effective in removing chemicals from groundwater. Both technologies are in place at three NASA-funded groundwater treatment plants – one located on JPL property; another in Altadena operated by the Lincoln Avenue Water Company (LAWC); and a third plant operated by the City of Pasadena. These technologies have been effectively removing perchlorate and VOCs from groundwater as part of NASA’s CERCLA groundwater cleanup program at JPL.They have also proven to be effective in removing emerging chemicals including PFAS. The treatment systems enable LAWC and the City of Pasadena to provide their customers with a continuous supply of drinking water that meets all state and federal clean drinking water standards.

Groundwater Monitoring – Well Water Sampling

Scientific research is central to NASA’s objective to implement a sound and comprehensive cleanup. Using various methods, NASA continually seeks to evaluate conditions and the extent and movement of chemicals in groundwater. Quarterly groundwater samples are taken from the 25 NASA monitoring wells located throughout the area. Results are placed on the NASA water cleanup website at

Annual Institutional Control Reports

The approved final cleanup plan (i.e., ROD), signed in February 2018, included requirements for an annual Institutional Control (IC) report to ensure the effectiveness of ongoing groundwater treatment and prevent exposure to impacted groundwater at JPL. Those IC reports have been filed in each year and placed on the NASA water cleanup website at

Regulatory Oversight Continues

Cleanup at and in the vicinity of JPL continues under CERCLA requirements, which include a required review of cleanup efforts every five years. An initial Five-Year Review was completed in February 2012; a second was completed in January 2017; and a third Five-Year Review, covering the calendar years from 2017 to 2021, has now been completed, approved by federal and state regulators, and filed. All three Five-Year Reviews determined that – with EPA concurrence in each case – the three NASA-funded groundwater treatment systems currently in place, combined with NASA’s comprehensive groundwater monitoring system, continue to be “protective of human health and the environment.”

Factsheets on each of the Five-Year Reviews have been placed on the NASA water cleanup website at


Last Modified: 9/14/2022 11:55:29 AM
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