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 15, 2005

Point of Contact:
Paul G. Landry
1400 Weston Way
P.O. Box 2653
West Chester PA 19380-2653 
Tel: 610-701-3000 
Fax: 610-701-3168
Email: landryp@

Letterkenny Army Depot: Building 37
Chambersburg, PA


The groundwater system beneath the site is a complex, folded and fractured limestone aquifer that exhibits wide variations in seasonal water levels and well yields and that contains a well-developed epikarstic zone. Groundwater beneath the site flows to the south, discharging in a series of off-post springs about 1.5 miles from the boundary of Letterkenny Army Depot (LEAD).

Targeted Environmental Media:
  • - Fractured Bedrock


Major Contaminants and Maximum Concentrations:
  • - Trichloroethene (0 µg/L)
  • - 1,1,1-Trichloroethane (0 µg/L)
  • - Tetrachloroethene (0 µg/L)
  • - 1,2-Dichloroethane (0 µg/L)
  • - 1,1-Dichloroethene (0 µg/L)
  • - 1,1-Dichloroethane (0 µg/L)
  • - Vinyl chloride (0 µg/L)
  • - Chloroethane (0 µg/L)

Site Characterization Technologies:

No technologies selected.

Remedial Technologies:

  • - Bioremediation (In Situ)
    • Reductive Dechlorination (In Situ Bioremediation)
A bench-scale microcosm study indicated that the microbial degradation of the VOCs could be greatly enhanced under anaerobic conditions through the addition of sodium lactate. A 6-month pilot scale study followed. The results indicated that the discharge of VOCs to the springs was nondetectable within 1 month of injection. Biological indicator compounds, particularly methane, also showed marked increases in concentration.

In late 2000, the Army implemented the enhanced bioremediation effort on a full-scale basis. The program involves the introduction of sodium lactate, with a tracer dye, into a series of injection wells over a 30-day period every 6 to 8 months. Bi-monthly groundwater samples are collected from a series of on-site and off-site locations for analysis of lactate, dye, VOCs, and dissolved gases to track the progress of cleanup.

Remediation Goals:

Not provided in information reviewed.


Analytical results indicate that the sodium lactate is distributed effectively throughout the source area and that the contaminant plume is continuing to biodegrade. VOC levels in off-post wells and springs have rapidly declined and remained below applicable or relevant and appropriate requirements (ARARs) since 2002. On-post production of medium and light molecular weight daughter products has shown a consistent decline to near ARAR concentrations in 2003, while primary solvents have generally declined and remained below ARARs since 2002.

Lessons Learned:

Landry, Paul G.; Paul R. Stone III. 2005. Enhanced bioremediation of chlorinated solvents in karst limestone bedrock using sodium lactate. The Eighth International In Situ and On-Site Bioremediation Symposium, Baltimore, Maryland. June 6-9.

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