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


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Fractured Bedrock Project Profiles

Last Updated: December 31, 2010

Point of Contact:
Jon Bornholm
USEPA 61 Forsyth Street, S.W.
Mail Code: 9T25
Atlanta 30303-8960 
Tel: 404-562-8820 
Email: bornholm.jon@
pa.gov

Chemtronics, Inc.
Swannanoa, NC


Hydrogeology:

The Chemtronics Site lies within the Blue Ridge geologic province. The Blue Ridge province is predominantly composed of ancient igneous and metamorphic rocks. These rocks have been complexly folded and faulted in a northeasterly direction, parallel to the regional trend of the mountains. These structural and metamorphic imprints are reflected in the topographic and drainage patterns
within the region.

Groundwater recharge in this area is derived primarily from local
precipitation. Generally, the depth of the water table depends on the
topography and rock weathering. The water table varies from the ground surface in the valleys (streams) to more than 40 feet below the ground surface in sharply rising slopes.
The aquifer underlying the Site can be subdivided into a surficial zone and a
bedrock zone. The surficial zone refers to the overlying saprolite and the
bedrock zone includes the weathered and fractured region of the bedrock. These
two zones are considered one aquifer as it was demonstrated in the RI that
these zones are interconnected.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

The exact extent of the plume is undefined.

Major Contaminants and Maximum Concentrations:
  • - 1,2-Dichloroethane (95,000 µg/L)
  • - Benzene (4,700 µg/L)
  • - 1,2-Dichloroethene (120 µg/L)
  • - Bromoform (1,100 µg/L)
  • - Chloroform (1,900 µg/L)
  • - Methylene chloride (9,200 µg/L)
  • - Trichloroethene (1,200 µg/L)
  • - Chromium (104 µg/L)

Site Characterization Technologies:

No technologies selected.


Remedial Technologies:

  • - Pump and Treat
Comments:
There are two plumes at the site. The first is controlled by a bedrock well set at 126.5 feet. The second plume is contained using 12 extraction wells. The Front Valley design extraction flow
rate is approximately 4 gallons per minute (gpm). The Back Valley design extraction flow rate is approximately 19 gpm. The system began operation in 1993. In 2006 the average pumping rates were 2.09 and 6.79 gpm respectively.
Remediation Goals:

1,2-Dichloroethane 5 ug/L
Benzene 5
Bromoform 100
Chloroform 100
Methylene Chloride 60
Trichloroethene 5
Chromium 50


Status:

The pump and treat system continues to operate. Concentrations in monitoring wells have fallen but are still well above cleanup levels.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0402957

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For more information on Fractured Bedrock, please contact:

Ed Gilbert
Technology Assessment Branch

PH: (703) 603-8883 | Email: gilbert.edward@epa.gov