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RCRA Facility Investigation and technical Impracticability Demonstration

Southington, Connecticut

Services: Investigation
Clients Served: Industrial

The site, which was formerly a large-scale overhaul and repair facility in Southington, Connecticut, is located in a GA groundwater classification area. Groundwater beneath the site had been contaminated with volatile organic compounds -- primarily tetrachloroethylene; trichloroethylene; and 1,1,1-trichloroethane. Following completion of a RCRA Facility Investigation and Corrective Measures Study/Corrective Measures Implementation, the available data were evaluated to determine compliance with the Connecticut RSRs including determining whether or not DNAPL had been removed or contained to the maximum extent prudent and the technical infeasibility or impracticality of restoring the aquifer beneath the site to drinking water quality.

Geologic and hydrogeologic conditions beneath the site, coupled with the documented distribution of DNAPL and dissolved-phase VOC contamination, were thoroughly evaluated with respect to contaminant fate and transport characteristics to provide a detailed analysis of aquifer restoration/RSR compliance options, including monitored natural attenuation. Calculations of restoration times, evaluations of plume areas, and hydrogeologic and geochemical characteristics of each of six identified plumes, documentation of a realistic hydrogeologic model for the site, and compilation of over 100 references on DNAPL and related topics were performed as part of the evaluation. The project included an estimation of potential remediation times for various portions of the aquifer based on a number of site-specific and contaminant characteristics using batch-flush calculations and plume lengths and an extensive literature review on the subject of aquifer restoration where DNAPL chemicals are present in the saturated zone.

Throughout the course of the evaluation, LEA and the client maintained a close working relationship with the senior-level management at the predecessor to the Connecticut Department of Energy Environmental Protection (DEEP) to ensure that the evaluation would meet expectations for thoroughness and technical defensibility. Since no other technical impracticability argument had been accepted prior to submission of the evaluation report and subsequent related documents, an important corollary objective for the project was to provide a comprehensive, detailed evaluation that could serve as a model for future submissions to support technical impracticability arguments.

Highlights

  • Facility investigation performed pursuant to RCRA and Connecticut program requirements.
  • Installation of over 800 soil borings and 17 groundwater monitoring well clusters and approximately 40 shallow groundwater monitoring wells.
  • Chemical analysis of over 2,000 soil, groundwater, surface water and sediment samples.
  • Development of first ever and first successful Technical Impracticability Demonstration in Connecticut.
  • Evaluation of DNAPL fate and transport in complex hydrogeologic environment in an unconsolidated aquifer.
  • Completion of Documentation of Environmental Indicator Determinations CA 725 and CA 750.