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: December 31, 2010

Point of Contact:
Christopher Corbett
USEPA 1650 Arch Street
Mail Code: 3HS20
Philadelphia PA 19103 
Tel: 215-814-3220 
Email: corbett.chris@
epa.gov

Berks Sand Pit
Longswamp twp, PA


Hydrogeology:

The Berks Sand Pit is located in the Reading Prong section of the New England Physiographic Province. Precambrain aged metamorphosed igneous, sedimentary and volcanic rocks comprise the highlands of the Reading Prong; the intermontane valleys are comprised of Cambro-Ordovician sediments consisting of limestone, dolomite, marble, and quartzite. Disseminated magnetite, and cornwall-type magnetite deposits occur throughout the Reading Prong. Magnetite rich pegmatites and massive magnetite was observed in three boreholes. In the vicinity of the site the saprolite consists of a light brown, tan to orange clay with some silt and sand, and quartz and feldspar fragments. The saprolite changes to clay and sand with quartz and weathered granitic gneiss fragments at depth. Some local zones in the saprolite show evidence of foliation and relict structures. The granitic gneiss is moderately to very closely fractured. Many fractures encountered in the boreholes contained chlorite filling and/or hematite staining on the fracture surfaces. Extensively weathered zones (possibly weathered fracture zones) were observed the maximum expected depth of significant fracture zones and weathered fractures, as determined from the cross-hole seismic velocity measurements, is approximately 150 to 200 feet below the ground surface. The granitic gneiss is highly weathered throughout the area and the thickness of the weathered overburden is quite variable. There is, in general, no distinct boundary between the overburden and the weathered bedrock. Rather, there is a gradual change from saprolite to weathered granitic gneiss to fresh granitic gneiss.

Two groundwater flow regimes have been identified at the site. A shallow flow regime occurs in the overburden and a deep flow regime occurs in the fractured bedrock. The shallow flow regime consists primarily of saprolite and highly weathered bedrock. Water in this shallow aquifer may occur as perched zones, generally above saprolitic layers, and under confined to semi-confined conditions, generally beneath saprolitic layers.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

The maximum depth of contamination was estimated to be between 250 and 300 feet. In 1994 the TCA plume that was greater than the MCL (200 ug/L) was approximately 1,800 feet long at its longest and 700 feet wide at its widest.

Major Contaminants and Maximum Concentrations:
  • - 1,1,1-Trichloroethane (7,300 µg/L)
  • - 1,1-Dichloroethene (3,500 µg/L)
  • - 1,1,2,2-Tetrachloroethane (25 µg/L)

Site Characterization Technologies:

  • - Borehole Geophysics
    • Other (Cross Borehole Seismic)
  • - Vertical Chemical Profiling
    • Packer Isolation
  • - Coring

Remedial Technologies:

  • - Chemical Oxidation (In Situ)
    • Fenton's Reagent
  • - Pump and Treat
Comments:
A pump and treat system was installed in 1993. An ISCO pilot was begun in 2001. It was successful and has been used periodically since.
Remediation Goals:

MCLs for TCA (200 ug/L) and 1,1-dichloroethene (7 ug/L)


Status:

EPA has treated approximately 435 million gallons of contaminated groundwater at the permanent groundwater treatment facility since March 1993. The plume of contaminated groundwater decreased over 75 percent since 1994.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0301434

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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