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 30, 2010

Point of Contact:
Charlie Root
USEPA 1650 Arch Street
Mail Code: 3HS21
Philadelphia PA 19103 
Tel: 215-814-3193 
Email: root.charlie@
pa.gov

A.I.W. Frank/Mid-County Mustang
Exton, PA


Hydrogeology:

The geology of the study area consists of unconsolidated, silty, clay-rich soils overlying the bluish-gray limestone and dolomite of the Conestoga Limestone, Ledger Dolomite, and the Elbrook Formation.

The local aquifer is formed by the carbonate bedrock units that underlie the area. These include the Conestoga Limestone and Ledger Dolomite at the site. Groundwater migration through these units is through fractures and solution channels and along bedding planes within the rock mass. Intergranular permeability and porosity are very low. The water table at the site is found within the bedrock material. Depth to groundwater ranges from nine to 26 feet below ground surface throughout the study area. A northwest- to-southeast-trending groundwater divide that bisects the AIW Frank portion of the site has been delineated.

The Conestoga Limestone displayed a greater abundance of solution cavities/ voids than did the Ledger Dolomite in the site vicinity. However, the Ledger Dolomite appeared to have a greater abundance of fracture zones than the Conestoga Limestone.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

In 2005 the 10 ug/L line of the TCE plume was about 2,920 feet long and 320 feet wide. Vertical depth was not given.

Major Contaminants and Maximum Concentrations:
  • - 1,1-Dichloroethene (1,900 µg/L)
  • - 1,1-Dichloroethane (780 µg/L)
  • - 1,2-Dichloroethene (10,400 µg/L)
  • - 1,1,1-Trichloroethane (500 µg/L)
  • - Trichloroethene (6,850 µg/L)
  • - Toluene (1,400 µg/L)
  • - Vinyl chloride (22 µg/L)
  • - Tetrachloroethene (68 µg/L)

Site Characterization Technologies:

  • - Coring

Remedial Technologies:

  • - Chemical Oxidation (In Situ)
    • Permanganate
  • - Pump and Treat
Comments:
The pump and treat system became operational in 2000. It runs unattended 24/7 and pumps an average of 96 gpm.
Remediation Goals:

Cleanup goals are MCLs when available.
Trichloroethene 5
1,1,1-Trichloroethane 200
1,1-Dichloroethene 7
1,1-Dichloroethane 81
1,1,2-Trichloroethane 5
cis-1,2 Dichloroethene 70
1,2-Dichloropropane 5
Tetrachloroethene 5
Vinyl Chloride 2
Toluene 1,000
Chloroform (THM) 100
Arsenic 10
Manganese 80


Status:

Pump and treat continues and groundwater concentrations are decreasing. The site has had at least one full scale treatment with sodium permanganate.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0300773

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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