Union Chemical Company ran a paint stripper and solvent recovery operation in South Hope, Maine starting in 1967. By 1984, state regulators had shut down waste treatment at the plant after years of violations, leaving roughly 2,000 drums and 30 tanks of hazardous waste on the property. Leaking drums, spills, and improper wastewater disposal contaminated both soil and groundwater. EPA added the site to the National Priorities List (NPL) in October 1989.
Contaminants found at the site include volatile organic compounds (VOCs) such as trichloroethene, tetrachloroethene, chloroform, and xylene in groundwater, soil, and surface water. Heavy metals including arsenic, lead, nickel, and zinc were detected in groundwater, soil, sediment, and surface water. Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene and pyrene were found mainly in soil and sediment. The chemical 2,3,7,8-tetrachlorodibenzo-p-dioxin was also detected in buildings on the property.
Cleanup began in earnest after EPA selected a remedy in December 1990. Responsible parties demolished contaminated buildings by May 1994 and then ran a soil vapor extraction system with 28 groundwater wells and 91 hot air injection points from 1996 to 1998. Chemical treatments using potassium permanganate, molasses, and sodium lactate helped address groundwater contamination. Closure sampling in fall 1998 confirmed soils met cleanup standards. About 96 percent of original contamination has been removed from soils, bedrock, and groundwater. In 2011, EPA determined it was technically impracticable to reduce residual groundwater contamination to drinking water standards. A Record of Decision Amendment in November 2013 adjusted the remedy to reflect this finding.
EPA and the State of Maine deleted the site from the NPL on September 21, 2018, after determining all necessary cleanup had been completed. An environmental covenant recorded on August 2, 2017, prohibits groundwater extraction and requires vapor barriers or sub-slab depressurization systems in any future buildings. Human exposure is considered under control, and groundwater migration is stabilized. Long-term groundwater monitoring continues every two years, and EPA conducts five-year reviews, with the most recent completed on September 14, 2022.
Community members can contact the EPA's Community Involvement Coordinator or Remedial Project Manager with questions. Public documents, five-year reviews, and fact sheets are available through the EPA Superfund website. Hard copies are also available at the EPA Region 1 records center in Boston and the Hope Town Office in Hope, Maine.
