Old Southington Landfill

Overview

The Old Southington Landfill covers 11 acres in Southington, Connecticut. It accepted municipal and industrial waste from 1920 to 1967, then was subdivided for development in 1973. Contamination reached a nearby municipal water supply well, prompting the EPA to add the site to the National Priorities List in 1984. The site has since completed all cleanup construction and was deleted from that list on September 12, 2018.

Contamination at the site is widespread across multiple media types. Groundwater holds volatile organic compounds (VOCs) including trichloroethene, tetrachloroethene, benzene, and vinyl chloride, plus metals such as arsenic, lead, cadmium, and mercury. Soil and sediment contain polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Air contains vapors of trichloroethene, tetrachloroethene, and benzene. Surface water holds trichloroethene, carbon disulfide, and metals like manganese and zinc. In all, EPA identified more than 100 contaminants of concern at the site.

Cleanup was organized into two operable units (OUs). OU1 addressed the landfill cap and resident relocation, with a Record of Decision (ROD) issued in September 1994 and construction completed by 2001. All homes and businesses on the landfill were permanently relocated. The northern section received a single-layer low-permeability cap, while the southern section got a double-layer cap. A hot spot area was excavated and placed in a lined cell beneath the cap, and a gas vent system was installed. OU2 addressed groundwater, with a ROD issued in September 2006 and remediation running from 2010 to 2011. Long-term groundwater monitoring continues. EPA has conducted five-year reviews in 2005, 2010, 2015, 2020, and September 2025 to confirm the remedy stays protective.

The EPA has determined the site poses no unacceptable risk to human health or the environment. Human exposure is under control, with no current pathways for people to contact contamination. Groundwater migration has been stabilized, and monitoring will continue to confirm contaminated groundwater stays in place. The northern portion of the site is now a passive recreational park where visitors can walk, kayak, birdwatch, and bring dogs. The southern portion remains closed to protect the landfill cap.

Institutional controls (ICs) remain in place across the site and on two nearby downgradient properties. They restrict groundwater consumption, prohibit residential development, and prevent construction or activities that could damage the cap or cause vapor intrusion. These controls will stay in place as long as contamination and cleanup components remain. Deletion from the National Priorities List does not prevent future Superfund action if it becomes necessary. Community members with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager.