Modern Landfill is underlain by low-grade metamorphic rocks of
Cambrian age, including (from oldest to youngest): Harpers Formation phyllite, Antietam Formation meta-sandstone, and Vintage Formation crystalline dolostone. Regional rock foliation strike is N70/ E. The bedrock materials are isoclinally folded in a synform structure dipping 60/-80/ to the south-southeast with an overturned southern limb, and having a low angle axial dip to the east-northeast. In addition to foliation and associated small-scale isoclinal folds, cleavage and kink folds are observed in outcrops and rock cores. Fracture systems recognized at the Site are parallel, perpendicular and diagonal to the foliation strike. A
mantle of weathered in-place saprolite is prevalent at the Site, and can attain significant thicknesses in areas
of converging subsurface discontinuities and increased calcite content of the rock mass where extensive
weathering has occurred.
Groundwater flow beneath the Site is generally from south to north, with recharge occurring from precipitation in the south and discharge to streams flowing to the north. The rocks in the area have a low primary porosity. Consequently, the flow of groundwater is controlled by the rock mass discontinuities.
Targeted Environmental Media:
 Fractured Bedrock
Extent of the plume was not identified in the EPA documentation
Major Contaminants and Maximum Concentrations:
- Trichloroethene (Not given)
- 1,2-Dichloroethene (Not given)
- Carbon tetrachloride (Not given)
- Benzene (Not given)
- Vinyl chloride (Not given)
- Chloroform (Not given)
- 1,1-Dichloroethane (Not given)
- 1,1-Dichloroethene (Not given)
- 1,4-Dichlorobenzene (Not given)
- Methylene chloride (Not given)
- Pumping Tests
- Coring
- Other (Linaments)
- Pump and Treat
Comments:
The western groundwater extraction system came online in 1985. The eastern groundwater extraction system came on line in 1986. With some subsequent modifications there were 27 extraction wells on site.
In 1999 the western extraction system was replaced. The new system consists of two elements: (i) a blast trench constructed by shattering existing bedrock in place to depths of
105 feet using controlled blasting techniques; and (ii) an engineered backfill trench constructed by replacing
overlying low permeable overburden materials with a highly permeable sand to a depth of 20 feet. The total
length of the EWGCS is 2,825 feet and is comprised of over 195,000 cubic yards of modified native subsurface materials.
Groundwater cleanup goals were risk based or US MCL or PADEP MCL whichever were lower. The chemicals listed above are a partial list of contaminants of concern.
The pump and treat system continues operation. There are currently 16 active extraction wells. Monitoring wells downgradient from the extraction system show minimum contaminant concentrations. The extraction wells and monitoring wells within the extraction system show variable concentrations.
http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0301322
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