The overburden aquifer is composed of
weathered and reworked bedrock material. This material consists of clay to gravel-size material that has been eroded and redeposited in meandering stream deposits that make-up the Schuylkill River floodplain.
The underlying bedrock aquifer is composed of interbedded conglomerates, sandstone, siltstone, and shale
units and are collectively referred to as the Gettysburg Formation. These rock units were laid-down in an ancient meandering stream and river environment. Sedimentary layers within the Gettysburg Formation are divided by bedding planes. The sedimentary layers over time have been rotated into an east-west orientation with a northward dip between 12 and 20 degrees. Some of the bedding planes have separated
into what are referred to as bedding plane fractures. Oriented perpendicular to and connecting the bedding planes fractures to various degrees are joint fractures. The degree of jointing is dependent on the thickness and brittleness of the sedimentary layers. Ground water flow in the bedrock aquifer is restricted to movement along the bedding plane fractures and joints. The intergranular porosity, where present, also contributes to ground water movement. Intergranular porosity contributes more to the storativity of the aquifer than to flow though the aquifer.
Targeted Environmental Media:
 Fractured Bedrock
The contaminants were in the overburden and shallow bedrock groundwater. Bedrock monitoring wells were set at 65 feet bgs.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (1,900 µg/L)
- 1,2-Dichloroethene (730 µg/L)
- Tetrachloroethene (Not given)
- Vinyl chloride (Not given)
- 1,2-Dichloroethane (Not given)
- 1,1,1-Trichloroethane (Not given)
- Pumping Tests
- Pump and Treat
- Bioremediation (In Situ)
- Reductive Dechlorination (In Situ Bioremediation)
Comments:
The biostimulant used was hydrogen release compound.
MCLs are the cleanup goals for groundwater.
The pump and treat system, which began operation in April 1999, is turned off and biodegradation continues. On May 26, 2010 an Explanation of Significant Differences was issued to change the remedy to enhanced bioremediation.
The average concentration in wells with detections is 8 ug/L TCE.
http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0300596
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