Former Market Place Shopping Center Site, Hilton Head, South Carolina

State Coalition for Remediation of Drycleaners Site Profiles

Description
Historical activity that resulted in contamination.

The former Market Place Shopping Center Site is located on Hilton Head Island, Beaufort County, South Carolina. The former facility operated as a Dryclean USA using perchloroethene and was located in a strip mall building which has been demolished. The site is currently occupied by a supermarket and pharmacy shopping plaza. Approximately 4 feet of fill soil was placed over the area previously occupied by the drycleaner. Land use is commercial to the north and east, residential to the south and west. The site is generally flat with an average elevation of 11 feet above mean sea level. There is a stormwater, tidal drainage lagoon with drainage to a canal that runs through a plantation community to the south. There are 11 public supply wells within a 2-mile radius of the site. The closest one is 2/10ths of a mile away.

Remediation Status: In groundwater monitoring

Contaminants
Contaminants present and the highest amount detected in both soil and groundwater.

Contaminant	Media	Concentration (ppb)
cis-1,2-Dichloroethene	groundwater
Tetrachloroethene (PCE)	groundwater	5,900 ppb
Trichloroethene (TCE)	groundwater
Vinyl Chloride	groundwater

Site Hydrology

Deepest Significant Groundwater Contamination:		41ft bgs
Plume Size:		Plume Length: 250ft Plume Width: 200ft Plume Thickness: 45ft
Average Depth to Groundwater:		10ft

Lithology and Subsurface Geology

fine silty sands, clay and shellhash.

Gradient: 0.006ft/ft

Pathways and DNAPL Presence

Groundwater

Sediments

Soil

DNAPL Present

Remediation Scenario

Cleanup Goals:

Groundwater <5ppb of PCE, <5ppb of TCE, <70ppb of cis,1,2-DCE, <100ppb of trans, 1,2-CDE, <2ppb vinyl chloride

Technologies

Ex Situ Other

Why the technology was selected:
Projected effectiveness - time to cleanup, cost, noise generation (Hilton Head has noise ordinances.)

Date implemented:
June 1, 2002 system operational. System shut down May 2007.

Other technologies used:
Air-Sparging with Ozone Injection.

Results to date:
MW-2-I recorded the highest PCE levels at 26,800 ppb during initial sampling. The sparge system began operation in June 2002 and reduced PCE levels in MW-2-I to 242 ppb in April 2003. However, PCE levels rebounded to 3,810 ppb in January 2004 and continued to climb. The sparge system was shut down in May 2007 due to recurring equipment failures. As of September 2011, PCE in MW-2-I has stabilized around 5,900 ppb. The original plume was ~ 50,000 sq ft. The overall dimensions of the plume remain similar to the original size. However, PCE levels have been reduced by ~78%, there is a marked increase of degradation products, and we have not seen contaminant migration.

Next Steps:
A comprehensive file review will be conducted after the April 2012 annual sampling event.

Cost to Design and Implement:
$311,000

Costs

Cost for Assessment:		$160,000
Cost for Operation and Maintenance:		<$50,000
Total Costs for Cleanup:

Contacts

Paul M. Bergstrand, P.G., Project Manager.
South Carolina Department of Health and Environmental Control, Columbia, South Carolina, 803-896-4016
bergstpm@dhec.sc.gov

Perry Kelso, P.G., Project Manager for Assessment Phase
Ecology and Environment, Tallahassee, Florida 850-574-1400

Walter Gerald, Project Manager for the Remediation Phase
Earth Tech, Inc., Greenville, South Carolina 864-234-8925

Site Specific References

Annual GW Monitoring Report, 4-2004.

Annual GW Monitoring Report, 6-2011.

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U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

State Coalition for Remediation of Drycleaners Site Profiles