Harlan County, Kentucky is located in the Cumberland Mountain section of the Eastern Coalfields Region of Kentucky. The area near the Site is underlain by the Pennsylvania-aged rocks in the
Hance Formation of the Breathitt Group. The Site is in the valley of the Cumberland River, and alluvial deposits up to 30 feet thick lie above the bedrock. The upper bedrock unit in the area is the Cawood Sandstone Member of the Hance Formation. This sandstone unit grades laterally into siltstone and thin-bedded sandstone, and contains thin discontinuous coal seams. The base
of the Cawood Sandstone occurs at 100 to 130 feet below the ground surface, and is underlain by a portion of the Hance Coal Zone that consists of four seams interbedded with sandstone, silty
sandstone and shale. The principal coal seam is the Terry's Fork coal bed that occurs at the base of the Hance coal zone. The Site is located on the Cumberland Mountain overthrust block, south-southeast of the Pine Mountain overthrust fault and north-northwest of the Cumberland Mountain within an east-west trending synclinal trough. To the north, the bedrock dips three to five degrees to the southeast. To the south, the bedrock dips one degree or less to the north-northwest. There are
northwest-southeast trending faults in the area that are associated with the Pine Mountain Overthrust Fault.
The Site is underlain by two significant water-bearing units. The uppermost, alluvial deposits consisting of well to poorly sorted accumulations of sand, silt, and clay occur at ground
surface. The alluvial deposits are twenty-five to thirty feet thick in the vicinity of the Site. They generally contain ground water under unconfined conditions, at depths averaging
twenty feet below existing land surface.
Study area bedrock wells range in depth from 58 to 639 feet below ground surface. The potentiometric surface in the bedrock aquifer is about 24 feet below grade at the Site. Because the alluvial water table is higher in elevation than the potentiometric surface of the bedrock unit, recharge from the overlying unit into the bedrock is likely.
Targeted Environmental Media:
- Fractured Bedrock
The 1992 ROD estimates the lateral extent of the plume to be half a mile. The 1996 ROD estimates the vertical extent to be 160 feet.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (2,500 µg/L)
- 1,2-Dichloroethene (3,200 µg/L)
- Vinyl chloride (140 µg/L)
- Vertical Chemical Profiling
- Pumping Tests
- Pump and Treat
Comments:
The Interim RA was initiated in July 1993 and consisted of an onsite Recovery Well CMW-5-11 located in the deeper bedrock aquifer zone (at an approximate depth of 120 feet), an equalization tank, an air stripping tower, and a 10,000 pound activated carbon unit to treat the air stripper off-gas. The scope of the Interim response action was increased by incorporating the use of a ground-water recovery trench located in the shallow
alluvial aquifer and an additional ground-water recovery well in the intermediate aquifer with that of the system already operating in the deeper zones of the underlying bedrock aquifer. An additional deep aquifer recovery well was also installed. The off-gas treatment was changed to catalytic oxidation. These additions came on line in 1998.
MCLs were the selected cleanup goals.
The pump and treat system continues to operate. Contaminant concentrations have fallen bu they are still above cleanup goals.
http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0405125
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