Iron Horse Park

Overview

Iron Horse Park is a 553-acre industrial complex in North Billerica, Massachusetts. It has been on the federal Superfund National Priorities List (NPL) since September 1984, added after being proposed in September 1983. More than a century of manufacturing and rail yard operations left the site contaminated across soil, groundwater, sediment, and surface water.

EPA identified over 190 contaminants of concern across the site. These include solvents such as trichloroethene and tetrachloroethene, metals including lead, arsenic, chromium, and mercury, polycyclic aromatic hydrocarbons, benzene, pesticides like aldrin and endrin, and polychlorinated biphenyls (PCBs). Contamination is spread across four operable units (OUs) covering the former wastewater lagoons, the Shaffer Landfill, source control areas, and sitewide sediment and groundwater.

Cleanup has moved through multiple phases over several decades. Contaminated material from the former B&M Wastewater Lagoons was excavated and treated off-site. The 60-acre Shaffer Landfill was capped with gas collection, drainage, and leachate management systems installed. Asbestos materials were removed and an asbestos landfill was covered. Soil areas at multiple locations were capped. Sediment is being removed from B&M Pond, and other areas are undergoing monitored natural recovery. All remedial construction was completed in September 2022. EPA, the Massachusetts Department of Environmental Protection (MassDEP), and responsible parties are finalizing an operations, monitoring, and maintenance plan for long-term upkeep. The site's September 2023 five-year review confirmed that completed response actions protect human health and the environment. In August 2025, the site achieved "Sitewide Ready for Anticipated Use" status, meaning all cleanup goals for current and anticipated future land uses have been met. Human exposure and groundwater migration are both considered under control.

The site has been redeveloped as a mixed-use property. Twelve on-site businesses employ 399 people and generate roughly $198.6 million in annual sales. A 6-megawatt solar facility with approximately 19,000 to 20,000 panels was built on the Shaffer Landfill and went online in August 2014, providing energy to local schools and government through net metering. Institutional controls, including zoning restrictions that prohibit residential development, remain in place to protect public health and the cleanup components.

Community members with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager. For state-level questions, contact MassDEP. Public records are available at the Billerica Public Library at 25 Concord Road or at the EPA Region 1 Records and Information Center in Boston.