Pump and Treat of Contaminated Groundwater at the SCRDI Dixiana Superfund Site, Cayce, South Carolina

Site Name:

SCRDI Dixiana Superfund Site

Location:

Cayce, South Carolina

Period of
Operation:

Status: Ongoing
Report covers: 8/92 - 3/97

Cleanup
Type:

Full-scale cleanup (interim results)

Vendor:

EPA Contractor: Ebasco Services, Inc.
PRP Project Coordinator: de maximis, Inc.
PRP contractor: S&ME, Inc.
PRP Operations Contractor: O&M, Inc.

Technology:
Pump and Treat

- Groundwater is extracted using 15 wells and a 300-ft shallow extraction trench, at an average total pumping rate of 40 gpm
- Extracted groundwater is treated with air stripping and discharged to a POTW

Cleanup Authority:
CERCLA Remedial
- ROD Date: 9/26/86

EPA Point of Contact:
Yvonne Jones, RPM
U.S. EPA Region 4
345 Courtland St., N.E.
Atlanta, GA 30365
(404) 562-8793
State Point of Contact:
Yanqing Mo
South Carolina DHEC
Bureau of Hazardous and Solid Waste
2600 Bull Street
Columbia, SC 29201

Contaminants:
Chlorinated solvents

- Maximum concentrations detected during intial investigations were PCE (600 µg/L), TCE (130 µg/L), 1,1,1-TCA (560 µg/L), 1,1-DCE (470 µg/L), and 1,1,1,2-PCA (25 µg/L)

Waste Source:
Spills from poor waste handling practices, leaking drums

Type/Quantity of Media Treated:
Groundwater

- 20.6 million gallons treated as of March 1997
- Groundwater is found at 14 ft bgs
- Extraction wells are located in 4 aquifers, and all 4 aquifers are contaminated
- Hydraulic conductivity ranges from 5 to 45 ft/day

Purpose/Significance of Application:
Remediation at a site with complex hydrogeology, consisting of eight distinct hydrogeological units.

Regulatory Requirements/Cleanup Goals:
- Reduce the concentration of contaminants in the groundwater to primary drinking water standards or maximum contaminant levels (MCLs).
- Cleanup goals were established for 1,1,1-TCA (200 µg/L),TCE (5 µg/L), 1,1,2-TCA (5 µg/L), PCE (5 µg/L), 1,1,2,2-TCA (5 µg/L), 1,1-DCE (7 µg/L), chloroform (100 µg/L), carbon tetrachloride (5 µg/L), benzene (5 µg/L), and dichloromethane (5 µg/L)
- A secondary goal is to hydraulically contain the migration of contaminants in the groundwater.

Results:
- Groundwater monitoring results indicate that contaminant concentrations have not been reduced to below cleanup goals. Concentrations in the well with the highest concentration, however, have been reduced by approximately 81% since 1992.
- The plume was not contained from 1992 until November 1995. Hydrodynamic control of the plume has been maintained since November 1995.
- The P&T system has removed approximately 7 pounds of contaminants from the groundwater from 1992 to 1996.

Cost Factors:
- Actual costs during the EPA-lead portion of the P&T system operation were approximately $1,439,700 ($1,189,700 in capital and $250,000 in O&M), which correspond to $464 per 1,000 gallons of groundwater extracted and $200,000 per pound of contaminant removed.
- Costs for the PRP-lead portion of the operation were $294,000 for capital and $180,000 for O&M.

Description:
South Carolina Recycling and Disposal Inc (SCRDI) operated this site as an industrial waste storage facility until 1978. The starting date of operations at this facility is not known. Waste materials stored on site included solvents, phenols, specialty chemicals, hydrogen peroxide, and pyridine. In 1978, SCRDI applied for a waste management permit from the South Carolina Department of Health and Environmental Control (SCDHEC). After a site visit, the permit was denied because of poor waste management practices, such as materials stored in leaking containers, drums stored in exposed conditions, and improper waste handling procedures. In June 1980, SCDHEC implemented a preliminary groundwater study to determine the extent of subsurface contamination. Analytical results from this study indicated that halogenated organic and metal contamination was found on site. The site was placed on the NPL in August 1982 and a ROD was signed in September 1986.

Two distinct remedial systems have operated at this site; one operated from August 1992 to June 1994 (EPA-lead portion), and the other from November 1995 to present (PRP-lead portion). A Supplemental Site Investigation (SSI) was performed in 1994 and a remedial system optimization study was performed in 1995; as a result the system was modified to include 15 extraction wells, a 300 ft shallow collection trench, and a shallow stacked tray air stripper.

The EPA portion of this application was based on RI results which did not accurately characterize the site. Based on these results, wells were screened in two lower groundwater units, but not in an upper, contaminated unit. In addition, during the EPA portion, wells were screened across two units, which allowed contaminants to migrate from one unit to the other, previously uncontaminated unit.