The O'Connor site sits in Augusta, Maine, where a salvage and electrical transformer recycling business operated starting in the 1950s. Transformers containing polychlorinated biphenyl (PCB) oil contaminated the soil and groundwater over decades. An oil spill detected in 1972 threatened nearby Riggs Brook. The site was placed on the National Priorities List (NPL) in September 1983. The NPL is the EPA's roster of the most serious hazardous waste sites in the country.
Contaminants at the site include PCBs, lead and other metals, volatile organic compounds such as benzene and toluene, chlorinated compounds including various chlorobenzenes, and polycyclic aromatic hydrocarbons (PAHs). These were found in soil, groundwater, surface water, and sediment. The EPA identified them by assessing which people and ecological resources could be exposed, and by evaluating health and ecological effects from contact with those substances.
The main cleanup, carried out between 1996 and 1997, removed more than 19,000 tons of contaminated soil and sediment, demolished 64 tons of barn debris, and sent 71,220 gallons of contaminated water for off-site treatment. Clean fill was brought in to restore the site's original topography. Earlier work in 1984 included fencing the property, posting warning signs, and removing drums and storage tanks. In 1987, Central Maine Power extended the fence and removed additional contaminated material. A groundwater remediation effort ran from 2003 through 2004, with monitoring continuing through 2013.
The site was deleted from the NPL on July 22, 2014, after the EPA and the State of Maine determined all required cleanup responses were complete. Human exposure is currently under control across the entire site, and contaminated groundwater migration is stabilized with no unacceptable discharge to surface water. Groundwater monitoring elsewhere on the site has met drinking water standards since 2006. Institutional controls remain in place to restrict land use and prevent activities that could damage cleanup systems. These include zoning rules that prevent residential use and restrictions on excavation. A technical impracticability waiver applies to a 3 to 4 acre area where groundwater contamination remains. The most recent five-year review was completed on September 22, 2022, and the next is estimated between September and November 2027.
Community members can review site records at the Lithgow Public Library in Augusta or at the EPA Region 1 office in Boston. For questions, residents may contact the Community Involvement Coordinator or the Remedial Project Manager.
