Sigmon’s Septic Tank Site

Sigmon’s Septic Tank Site
EPA ID: NCD062555792
Location: Statesville, Iredell County, NC
Congressional District: 05
NPL Status: Final 2004

Project Manager

Site Repository
Iredell County Library
135 East Wales Street
Statesville, North Carolina 23677

Documents:

• Site Profile
• Additional Site Documents including Five Year Reviews, Records of Decisions (ROD) and Explanation of Significant Differences (ESD).
• For documents not available on the website, please contact the Region 4 Freedom of Information Office (http://www.epa.gov/region4/foiapgs/submit.htm).

The Sigmon’s Septic Tank Site is located at 1268 Eufola Road in Statesville, Iredell County, North Carolina. The property that comprises the Site is15.35 acres and is bound by Eufola Road to the north and Lauren Drive to the south.  Private landowners are located to the east and west of the Site. The Sigmon’s Septic Tank Service was owned and operated by the Sigmon family since 1948.  The business pumped septic tank wastes and heavy sludges from residential, commercial, and industrial customers; installed and repaired septic tanks; and provided a variety of industrial waste removal services.  From 1978 to 1992, the property owners placed septic wastes in several unlined lagoons which had been dug on the property. The  lagoon area (encompassing all the lagoons) dimensions are 213 feet long by 250 feet wide or approximately 1.2 acres. The waste was described as septage, grease, and milky white liquid.

In 1995, the North Carolina Environment and Natural Resources (NCDENR) required the closure of the lagoons. The lagoon sludge were excavated to a depth of 10 feet and mixed with sawdust. The excavated waste was then piled on-Site adjacent to the lagoon area. The lagoons were backfilled with soil from the north portion of the Sigmon’s property. The waste pile and lagoons still remain on-Site.

In 1998, the NCDENR conducted an extensive combined Preliminary Assessment/Site Inspection of the Sigmon's Septic Tank Site. The investigation confirmed the presence of groundwater contamination south and east of the Sigmon's property and supported previous results of organic and inorganic compounds within the waste pile and the lagoons. Barium, chromium, lead, manganese, mercury, chlorobenzene, 1,4-dichlorobenzene, and 1,2-dichlorobenzene was detected within several wells.

In March 2000, the NCDENR completed an Expanded Site Inspection (ESI) of the Sigmon’s Septic Tank Site.  The ESI included the collection of nine groundwater samples, ten soil samples and six surface water samples and sediment samples.  The samples were analyzed for inorganics, volatile organics, and extractable organics.  Several constituents were detected in the groundwater samples at concentrations either two times greater than background  levels or exceeding sample quantization limits .  Mercury was detected in the groundwater at 6.6 micrograms per liters (ug/l).

The Sigmon’s Septic Tank Site was added to the EPA’s National Priorities List (NPL), a list of sites nominated by the states for hazardous waste cleanup, in September 2004.

Cleanup Progress:  From October 2002 to 2005, the U.S. Environmental Protection Agency (U.S.EPA) conducted a Remedial Investigation/Feasibility Study (RI/FS). Several sampling investigation occurred during the remedial field investigations.  Based on the results from the 2002 and 2005 sampling events and the complex hydrogeology at the Site, the U.S. EPA decided to address the entire Site as two operable units (OUs):  OU1 for soil and OU2 for groundwater.  This strategy enabled the U.S. EPA to move forward with delineating the soil while continuing to delineate groundwater under OU2.  Further sampling investigations was conducted to verify if contaminants had migrated to additional drinking water wells. According to an April 30, 2005, draft Health Consultation by the Agency for Toxic Substance and Disease Registry (ATSDR) and the draft August 2005 RI Report, contaminants in drinking water wells located near the Site had the potential to adversely affect public health.

The residents living near the site was informed of the potential groundwater contamination resulting from past activities at the Site.  Drinking water wells in the area was sampled and analyzed for inorganic, volatile organics and extractable organics.  A total of seven (7) private drinking water wells had contamination that exceeds EPA's drinking water standards. Three of the seven private wells had nitrate levels greater than 10,000 parts per billion (ppb). ATSDR recommended not using water from the private wells to prepare infant formula until it was confirmed that the nitrate levels were below 10,000 ppb.  There were approximately thirty (30) additional drinking water wells located in the vicinity of the Site which had the potential to be adversely impacted.

EPA conducted a non-time critical removal action in March 2006.  Proposed actions for the removal at the Site included installing filters on private drinking water wells and providing bottled water to residents that were potentially impacted from the Site.  Post removal Site control were required to maintain the filters placed on the wells.  The filters will be replaced at intervals to obtain maximum effectiveness.  The U.S. EPA’s Science and Ecosystem Division agreed to take responsibility for maintaining the filters for one year.  After 2008, the residents would be responsible for maintaining the treatment system.