Sigmon's Septic Tank Service is a 15-acre former septic waste storage facility in Statesville, Iredell County, North Carolina. The site operated unlined lagoons from 1978 to 1992, leaving behind contaminated soil and groundwater. The EPA added it to the National Priorities List (NPL) in April 2005, which formally designated it as a priority Superfund cleanup site. The EPA has worked alongside the North Carolina Department of Environmental Quality (NCDEQ) throughout the investigation and cleanup process.
Eighteen chemical substances have been identified as contaminants of concern. In soil and groundwater, these include aluminum, arsenic, barium, benzo(a)pyrene, chromium, iron, manganese, mercury, thallium, vanadium, and zinc. Groundwater also contains 1,4-dichlorobenzene, with arsenic and iron appearing across both cleanup areas. The contamination affected groundwater both on and off the site, though the EPA has determined no private wells are currently affected. As a precaution, the agency installed filters on some private wells in homes where children reside and provided bottled water to affected residents.
The cleanup was organized into two operable units (OUs), which are distinct areas of work. For OU1, the EPA removed 2,700 tons of contaminated soil in 2009 and disposed of it off site. For OU2, the selected remedy is monitored natural attenuation (MNA), meaning the site relies on natural processes to reduce groundwater contamination over time, with regular monitoring to confirm progress. The NCDEQ now oversees that groundwater monitoring program on a biennial (every two years) schedule. Physical construction of all cleanup work was completed September 30, 2009, and the site gained national recognition in 2010 as the first Superfund site to complete cleanup using American Recovery and Reinvestment Act funds.
The most recent Five Year Review, completed in September 2023, confirmed the cleanup remains protective of human health and the environment. Human exposure is under control, contaminated groundwater migration is stabilized, and there is no unacceptable discharge to surface water. Institutional controls, including zoning restrictions, are in place to prevent residential development or other land uses that would be incompatible with cleanup levels. North Carolina's groundwater protection statutes also prevent exposure through private well construction. The site received a Sitewide Ready for Anticipated Reuse designation on June 27, 2019, meaning it can support industrial use going forward. It has not yet been deleted from the NPL.
Community members can stay informed through public notices, public meetings, and interviews that the EPA conducts as part of its outreach efforts. Anyone with questions about the site can contact the EPA Remedial Project Manager directly. Public records related to site work can be viewed at the Iredell County Library in Statesville.
