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: June 17, 2004

Point of Contact:
Theresa Santangelo-Dreiling
Colorado DOT
4201 E. Arkansas Ave. Rm. 290
Denver CO 80222 
Tel: 303-757-9793 
Fax: 303-757-9820
Email: theresa.santangelo@

Colorado DOT facility
Denver, CO


Unconsolidated unsaturated loess overlying bedrock
The top of the bedrock occurs between 3.9 to 5.5 meters below ground surface and consists of inter bedded claystones, siltstones, and sandstones.

Beneath the dry well sourse area, the bedrock is moderately to highly weathered to approximately 14.6 m bgs. The sandstones in the weathered zone are generallyloose to poorly consolidated and more permeable then the interbedded claystones. The sandstones have been interpreted to be the primary pathways of ground-water flow and contaminant transport. Hydraulic conductivities are 6x10-5 cm/sec and ground-water flow is 3-12 m/yr.

Targeted Environmental Media:
  • - Fractured Bedrock


Major Contaminants and Maximum Concentrations:
  • - Methylene chloride (2,500,000 µg/L)
  • - Tetrachloroethene (300 µg/L)
  • - Trichloroethene (300 µg/L)

Site Characterization Technologies:

  • - Tracer (dye) Test

Pumping tests

Remedial Technologies:

  • - Fracturing
  • - Bioremediation (In Situ)
    • Aerobic Oxidation
Application of an enhanced aerobic biological injection process utalizing hydrofracturing to address the low transport rates in a fractured claystone combined with the injection of dissolved methane to stimulate the production of the mono-oxygenase enzyme was implemented in 2002. The full-scale system consists of 40 nested shallow and deep injections spaced throughout a 20 acre area within the 100 ug/L and greater 1,1-DCE plume area. Methane, oxygen, and nutrients have been injected simultaneously over a two year period.
Remediation Goals:

None provided

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