Calhoun Park Area
Site Summary ProfileEPA ID: SCD987581337
Location: Charleston, Charleston County, SC
Lat/Long: 32.79154, -0 79.927219
Congressional District: 06
NPL Status: Superfund Alternative Approach
Affected Media: Ground water, Soil, Sediment, Surface Water
Cleanup Status: Physical cleanup activities are underway
Site Reuse/Redevelopment: In use - electrical substation
Site Manager: Craig Zeller (email@example.com)
The Calhoun Park Area Site (CPA) is located in Charleston, South Carolina. The CPA site includes the operating South Carolina Electric & Gas Company (SCE&G) Charlotte Street electrical substation, the former Calhoun Park, and portions of the former Ansonborough Homes property, Ludens Marine, and the National Park Service property. Calhoun Park, a former public recreational park, is now the site of a 1,100-car parking garage operated by the City of Charleston. The Ansonborough Homes portion of the site is currently occupied by soccer fields on the southern portion and additional development is expected for the remaining northern area. The former Ansonborough Homes housing project was razed during 1996 and 1997 by the City of Charleston.
Historically, several industries operated within this area, including a manufactured gas plant, a wood treating plant, a shipyard, and a dry dock. The manufactured gas plant operated from 1855 to 1957 at the site by predecessor companies to SCE&G. The former gas plant produced a product known as "town gas" by heating coal in the absence of oxygen. This process produced a combustible gas, which was distributed to area homes and businesses as fuel for gas lamps and cooking stoves. Liquid coal tar was a common byproduct of this process and is the primary source of environmental concern at this site.
The area surrounding the site is primarily commercial, but the Dockside Condominiums are located adjacent to the site.
The site is not listed on the National Priorities List (NPL), but is considered to be an NPL-caliber site and is being addressed through the Superfund Alternative Approach. This approach uses the same investigation and cleanup process and standards that are used for sites listed on the NPL.
Site soil was found to be contaminated with polynuclear aromatic hydrocarbons, volatile organic compounds (benzene, toluene, ethylbenzene, and xylene), and, to a lesser extent, inorganic chemicals (arsenic and beryllium). Coal tar has been observed in sediments, surface waters, and seeps along the adjacent Cooper River. Free coal tar product has been discovered in the ground water at four locations underlying the site.
Site Cleanup Plan
The cleanup plan for the Calhoun Park site covers two operable units (OUs): OU-1 (impacted soils, Non Aqueous Phase Liquid (NAPL) source areas, and shallow ground water) and OU-2 (surface water, intermediate ground water, and sediments in the Cooper River).
The Record of Decision (ROD) for OU-1 was issued in 1998. Cleanup activities included:
- Excavation and transportation of contaminated soils to a permitted landfill.
- Backfilling of the excavated areas with clean fill.
- Source removal of NAPLs from both the shallow and intermediate aquifer.
- Treatment of ground water through a combination of recovery wells/filtration system and phytoremediation.
- Additional sampling of surface water and sediment, following mitigation of coal tar discharge into Cooper River, to fully delineate the extent of contamination and potential threat to aquatic and terrestrial life.
The ROD for OU-2 was issued in 2002. Major cleanup elements included:
- Dense Non Aqueous Phase Liquid (DNAPL) removal to the extent practicable using either stationary or portable pumping equipment.
- In-situ treatment of impacted groundwater via chemical oxidation.
- Evaluation of containment measures if DNAPL removal does not mitigate potential migration of dissolved phase constituents.
- Ground water monitoring with the potential for 12 years of monitoring.
- Restrictions to future uses of intermediate ground water at the site through institutional controls.
A 2006 Explanation of Significant Differences for OU-1 identified three additional source areas of contamination for cleanup - a former wood treating operation, depositional areas surrounding the former steam plant, and the discharge outfall of the former oil-water separator - and revised the cleanup approach to include a chemical oxidant to inhibit the migration of source materials located in inaccessible areas (i.e., existing underground utilities and structures tied to the SCE&G substation).
Cleanup activities for OU-1 began in 1999. Cleanup work involved excavation and off-site disposal of 63,400 tons of impacted soils and debris, installation of approximately 50 NAPL recovery wells, collection and treatment of over three million gallons of ground water encountered during soils excavation work, and phytoremediation as a polishing step for shallow ground water.
Routine ground water monitoring and active NAPL recovery will continue for the foreseeable future. In general, NAPL recovery has ranged from 100 to 400 gallons per month.
Cleanup activities for OU-2 consisted of sediment capping in three areas of the Cooper River and treatment of the intermediate aquifer via injection of chemical oxidants. The initial in-situ chemical oxidation treatment at three areas immediately adjacent to the CPA site was conducted in 2005. A polishing treatment step was conducted during the Fall of 2006. Sediment capping work in Areas 2 and 3 of the Cooper River was conducted in the Summer of 2006. Physical cleanup for OU-2 is complete, except for installation of the sediment cap in Area 1 of the Cooper River.
Under an Administrative Order on Consent (AOC) with EPA, SCE&G completed site investigation activities at the site in 1996.
A 1998 an AOC was signed by EPA and SCE&G to facilitate the delineation, excavation and disposal of impacted soils in advance of construction and redevelopment activities at the site.
In 1999, EPA issued a Unilateral Administrative Order to SCE&G requiring implementation of the ROD for OU-1.
EPA has conducted a range of community involvement activities at the Calhoun site to solicit community input and to ensure that the public remains informed about site activities throughout the site cleanup process.
Ground water monitoring in ongoing at the site.
The sediment capping work in Area 1 is on hold pending construction of a new pier at the end of Charlotte Street in Charleston.
Site Administrative Documents
For more information or to view any site-related documents, please visit the site information repository at the following location. As new documents are generated, they will be placed in the information repository for public information.
Charleston County Main Library
68 Calhoun Street
Charleston, SC 29401
For documents not available on the website, please contact the Region 4 Freedom of Information Office.