The Billings PCE Superfund site spans roughly 1,000 acres in and around downtown Billings, Montana, stretching about three miles east-northeast from 24th and Central Avenue through several neighborhoods. The site was added to the National Priorities List in September 2021, making it eligible for federal Superfund cleanup funding. The U.S. EPA (Environmental Protection Agency) is leading the cleanup with oversight from the Montana Department of Environmental Quality (DEQ).
The primary contaminants are chlorinated volatile organic chemicals, including PCE (perchloroethylene or tetrachloroethene), TCE (trichloroethene), DCE (dichloroethene), and vinyl chloride. These chemicals sit in soil and groundwater beneath the site. They can evaporate and seep into buildings through cracks and unsealed seams, a process called vapor intrusion. Thousands of buildings sit above the contaminated groundwater, including homes, schools, churches, and businesses. The groundwater is not used for drinking water, so there is no immediate risk from drinking. Contaminated soils may pose health concerns to on-site workers and can continue to feed the groundwater plume. EPA performance measures show that human exposure is not under control at this site.
The EPA has organized cleanup into three Operable Units (OUs). OU1 targets vapor intrusion in buildings. OU2 targets contaminated soil and groundwater near the main source area at 7th and Central Avenue. OU3 addresses site-wide groundwater and vapor remedies. Removal work for OU1 finished in November 2024. Between 2022 and 2024, the EPA collected over 500 groundwater and soil samples, 200 sub-slab soil gas samples, and 190 indoor air samples. Vapor levels dropped in buildings where mitigation systems were installed. In July 2025, the EPA released a Proposed Plan recommending vapor mitigation systems in buildings for OU1. The EPA covers equipment and installation costs, and property owners pay for electricity, roughly the cost of running a 75-watt lightbulb continuously. A final decision in a Record of Decision is expected in 2026. OU2 work is moving more slowly, with the remedial investigation and feasibility study estimated to finish between June and August 2027.
Five businesses currently operate at the site, employing 22 people and generating about $2 million in annual sales. Institutional controls, including zoning restrictions that prevent residential development in certain areas, are in place to manage exposure risks.
Community members can check whether their property falls within the study area using an interactive map on the EPA's website. A Frequently Asked Questions flyer and an Institutional Controls fact sheet are also available. The public comment period on the Proposed Plan has closed, and the EPA will publish a Responsiveness Summary of comments received. Residents with questions can contact EPA or Montana DEQ staff directly using the information below.
