Bioremediation of Chlorinated Solvents in Fractured Bedrock at the Caldwell Trucking NPL Site
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The Caldwell Trucking Site consists of properties and groundwater contaminated by the disposal of residential, commercial, and industrial septic waste. Since 1981, over 300 private wells in the area have been taken out of service due to contamination, and the affected residences have been connected to the municipal drinking water supply system. The area of groundwater contamination is within fractured bedrock, and is contaminated with trichloroethylene and its associated biodegradation products (e.g., cis-1,2-dichloroethene and vinyl chloride) and 1,1,1-trichloroethane. The original Record of Decision stipulated that a groundwater recovery system (pump and treat) be installed at the facility. In February 1997, the U.S. EPA modified the groundwater remedial action schedule, allowing the PRPs to test the effectiveness of a permeable iron reactive barrier to intercept the contaminated groundwater before it discharges at a surface water seep. Monitoring results on the effectiveness of the iron wall indicated the wall reduced the volatile organic compound (VOC) levels in the seep but not to acceptable levels. As a result, additional treatment to reduce the levels of contamination reaching the seep was needed.

Geosyntec's Scope of Services

The PRPs requested permission to conduct a pilot test of enhanced in situ biodegradation (EISB) for a six-month period in the VOC source area at the site. Geosyntec implemented bioaugmentation at the site with a stable dehalogenating bacteria (KB-1), to accelerate the dechlorination within the aquifer. The PRPs presented the results of the pilot test to the U.S. EPA and New Jersey Department of Environmental Protection (NJDEP). These results indicated that EISB appeared to be reducing the level of VOCs in the source area at the site. The PRPs then requested U.S. EPA's permission for Geosyntec to perform a focused feasibility study for the purpose of amending the groundwater extraction and treatment system remedy. The U.S. EPA, after consultation with NJDEP, expects to make a decision on the PRP's request. Construction of the groundwater extraction and treatment system is on-hold, pending the U.S. EPA's evaluation of our alternate groundwater cleanup plans. Working with the University of Toronto, Geosyntec isolated and developed the KB-1dehalogenating bacteria used at the site. As the EISB design expert on the project, Geosyntec continues to provide technical support in assessing the data.

Notable Accomplishments

This was the first application of KB-1 bioaugmentation into a fractured bedrock groundwater environment. If Geosyntec's EISB remedy is approved by the U.S. EPA, it will potentially result in a cost savings of approximately $10 million over the conventional pump and treat remedy.

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Project Summary

  • Location: Fairfield, New Jersey, USA
  • Client: Confidential
  • Project Practice Areas: Contaminated Sites
  • Type of Facility: Industrial Site
  • Services Provided: Remedial Design; Pilot Testing
  • Type of Work: Bioremediation
  • Governing Regulation: Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)