Hazardous waste was dumped into unlined pits at this 10-acre site between 1979 and 1980, roughly 10 miles west of Buckeye, Arizona. Over 18 months, 3.28 million gallons of liquid waste and 4,150 tons of solid waste seeped into the soil and groundwater. The site was added to the National Priorities List in June 1986. EPA leads the cleanup, with support from the U.S. Army Corps of Engineers and the Arizona Department of Environmental Quality.
Forty contaminants have been identified in soil, groundwater, and soil gas. Key chemicals include volatile organic compounds (VOCs) such as trichloroethene (TCE), tetrachloroethene (PCE), benzene, and vinyl chloride, along with metals like chromium, copper, and lead. Several compounds, including TCE, PCE, benzene, and 1,2-dichloroethane, still exceed cleanup standards in groundwater. Risk assessments flag health hazards for anyone who drinks contaminated groundwater or contacts hazardous waste directly in the trenches, though breathing VOCs in outdoor air poses no apparent risk. Human exposure is currently under control, and groundwater migration is stabilized.
Cleanup construction was completed in September 1997. The main remedy includes a soil cap built in 1994, a pump-and-treat system using air stripping that has been running since 1992, and a soil vapor extraction (SVE) system that treats VOC-laden soil vapor with granular activated carbon. The upgraded SVE system installed in 2006 has recovered more than 223,000 pounds of VOCs. The pump-and-treat system has removed about 400 pounds of VOCs since 1994. The site is fenced and closed to the public, and zoning restrictions prevent residential use. The site achieved "sitewide ready for anticipated reuse" status in September 2012.
A fifth five-year review was completed in September 2021 and confirmed that cleanup actions continue to protect public health and the environment. The sixth five-year review is underway and must be completed by September 30, 2026. That review will inspect the site and its cleanup technologies, examine site data and maintenance records, and check for any new regulations affecting the cleanup. The Hassayampa Steering Committee reports monitoring findings to EPA twice a year. The site has not yet been deleted from the National Priorities List.
Community members who want to follow cleanup progress can review documents at the Arizona Department of Environmental Quality Records Center at 1110 W. Washington Street in Phoenix, Arizona, or by calling (602) 771-4380. EPA will post the 2026 five-year review report on its site webpage and send a copy to the EPA Superfund Records Center in San Francisco. For direct questions, contact EPA's Community Involvement Coordinator or Remedial Project Manager.
