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: January 1, 2011

Point of Contact:
Jill Lowe
USEPA 1650 Arch Street
Mail Code: 3HS21
Philadelphia PA 19103-2029 
Tel: 215-814-3123 
Email: lowe.jill@
pa.gov

Dublin TCE Site
Dublin Borough, PA


Hydrogeology:

The sequence of rocks underlying the Dublin area is part of a mixed zone of varying units of the Lockatong Formation. The interlayering is thought to be primary in origin, resulting from oscillations between lacustrine and fluvial conditions in a depositional basin environment. The Lockatong Formation consists mainly of thick-bedded gray and black siltstone and shale. The sediment of these units is believed to have been deposited in a lacustrine or swampy environment, under reducing conditions. Interbedded among the gray and black siltstones and shales are thinner reddish-brown sandy siltstone units. The sandy siltstone units are thought to have been deposited in an alluvial, more oxidizing environment.

The top of the bedrock at the Site is encountered between 5 and 12 feet below land surface. Based on drilling logs, the bedrock is comprised of interbedded gray and red beds of the Lockatong Formation dipping to the northwest.

The Lockatong unit generally provides adequate supplies of groundwater to wells for domestic uses. Groundwater flow in the study area is believed to be dominated by joint systems and dipping bed planes. In the more competent gray and black siltstone and shale units, permeability is maximum downward through the vertical joint systems, and storage is minor. In the reddish brown sandy siltstone units, permeability is greatest parallel to the sedimentary layering, and storage is greater. Generally, the permeability of the gray and black siltstones and shale units is an order of magnitude less than that of the reddish-brown sandy siltstone units.

In the area of the Site, groundwater generally is encountered between 14 and 53 feet below land surface and flows in a northwesterly direction.

Targeted Environmental Media:
  • - Dense Non-aqueous Phase Liquids (DNAPLs)
  • - Fractured Bedrock

Contaminants:

The vertical contamination is at least to 478 feet bgs.

Major Contaminants and Maximum Concentrations:
  • - Trichloroethene (55,000 µg/L)
  • - Chloroform (26 µg/L)

Site Characterization Technologies:

  • - Vertical Chemical Profiling
    • Packer Isolation

Remedial Technologies:

  • - Chemical Oxidation (In Situ)
    • Permanganate
  • - Pump and Treat
Comments:
The municipal supply well is used as a capture well and water pumped from it is treated using an air stripper as the primary treatment technology and then is discharged to the Dublin Borough municipal water distribution system.
Remediation Goals:

MCL of 5 ug/L for TCE


Status:

The municipal production well continues to be a pump and treat system.
Permanganate was injected in May 2008 and Spring summer of 2009.

The OU-2 ROD provides for a 14 well source area extraction system if the in situ chemical treatment does not perform to satisfaction.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0302401

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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