The bedrock is predominantly carbonate and solution-enlarged voids and conduits are present in the bedrock. An extensive network of interconnected openings (voids) has developed along horizontal fractures (bedding planes) and vertical fractures (joints) in the bedrock. Groundwater travels through these voids far more rapidly than would otherwise be the case.
In the source zone the overburden soil ranges from 1 to 9 feet thick.
Targeted Environmental Media:
- Dense Non-aqueous Phase Liquids (DNAPLs)
- Fractured Bedrock
The cause of the contamination was the release of 30,000 gallons of TCE in a 1971 rail accident.
The bedrock plume is at least 3.5 miles long. A large proportion of the NAPL in the bedrock appears to be located in the vadose zone, which is the part
of the bedrock above the normal position of the water table. This conclusion was reached by examining the
contamination levels in the monitoring wells at different times of the year. During the spring months, the
water table in the NAPL zone rises by over thirty feet into parts of the bedrock which are normally dry
during the rest of the year. This is due to the input of large volumes of uncontaminated water from Mud Creek. Ordinarily, the introduction of large volumes of clean surface water would be expected to lower TCE concentrations due to dilution. However, TCE concentrations rise dramatically in the NAPL-zone instead. This is believed to result from having groundwater contact highly contaminated bedrock which does not ordinarily contain water.
Major Contaminants and Maximum Concentrations:
- Trichloroethene (59,000 µg/L)
No technologies selected.
- Soil Vapor Extraction
- In Fractured Bedrock Vadose Zone
None provided
The ROD for the SVE in the fractured bedrock was signed 1999. As of November 2010 the system has not been put in.
There is no ROD for the groundwater contamination.
|