Potter's Septic Tank Service Pits

Overview

Potter's Septic Tank Service Pits sits in Maco, Brunswick County, North Carolina. It operated as a sludge hauling and oil spill cleanup facility from 1969 to 1976, leaving behind contaminated soil and groundwater. EPA added it to the National Priorities List (NPL) in 1989, formally designating it as a priority cleanup site. The area was later developed into a residential neighborhood, and homes are now connected to the public municipal water supply rather than private wells.

EPA has identified 75 contaminants of concern at the site, spread across soil, groundwater, or both. These include metals such as lead, mercury, chromium, and nickel; volatile organic compounds (VOCs) like benzene, toluene, and xylene; polycyclic aromatic hydrocarbons (PAHs) including naphthalene and pyrene; and pesticides such as DDT and dieldrin. All contaminants fall under one defined cleanup area, called Operable Unit 01.

Cleanup has happened in two major phases. In 1994, EPA and the North Carolina Department of Environment and Natural Resources excavated and sent off-site roughly 32,000 cubic yards of contaminated soil for treatment. A 2000 amendment to the original cleanup plan replaced several active treatment technologies with monitored natural attenuation (MNA), a process that lets contamination break down naturally over time while the site is regularly monitored. MNA began in 2001. Additional monitoring wells were installed and institutional controls, meaning legal restrictions on land and groundwater use, were placed on the property.

The most recent Five-Year Review, completed in September 2022, found the remedy protects human health and the environment in the short term. Groundwater contamination has stayed within the site boundary and has not reached residential drinking water because homes use the public supply. EPA also assessed whether harmful vapors from groundwater could enter buildings and determined that vapor intrusion does not threaten residents or workers. Groundwater migration is stable. To achieve long-term protection and formally close out the cleanup, restrictive covenants or other institutional controls still need to be fully put in place. The site is not yet deleted from the NPL. The next five-year review is estimated between August and October 2027.

Community members can stay involved through EPA outreach activities that include public notices, public meetings, and interviews about cleanup progress. Site records are available at the Leland Public Library in Leland, North Carolina. Three EPA contacts are assigned to the site and can answer questions about cleanup work or community involvement.