Soil & Groundwater Contamination Remediation

Soil & Groundwater Contamination Remediation

Location: Wyoming

Client: Confidential

Completion Date: 2003-present

Burns & McDonnell was retained by a confidential client to perform remedial action services for a former trucking facility. Soil and groundwater contamination potentially related to maintenance shop activities has been identified at the site, with the primary contaminants of concern being the chlorinated solvents trichlorothene (TCE), cis-1,2-dichloroethene (cis-1,2-DCE), trans-1,2-dichloroethene (trans-1,2-DCE) and vinyl chloride.

  • Source investigations
  • Remedial action design
  • Remedial action implementation
  • Routine groundwater monitoring

The client and the Wyoming Department of Environmental Quality (WDEQ) entered into a voluntary remedy agreement for performing remediation at the site in accordance with the requirements of the Voluntary Remediation Program (VRP). The selected remedial action was in-situ chemical oxidation (ISCO) combined with enhanced anaerobic bioremediation (EAB). The primary objectives were to reduce contaminant levels within groundwater and minimize potential exposure to possible receptors.

Burns & McDonnell successfully completed subsurface investigations in 2003 and 2004, which defined the limits of the contaminants in soil and groundwater. A source area of subsurface soil contamination was identified adjacent to the former maintenance shop building. The vadose zone is limited as groundwater is present at approximately 3 to 5 feet below ground surface (bgs). A groundwater plume extends from beneath the potential source area and has been shown to migrate downgradient to the eastern boundary of the site. Routine groundwater monitoring has been conducted at the site since 2004.

In 2006, Burns & McDonnell prepared a remedial action plan (RAP) presenting an innovative approach to remediate the soil and groundwater contamination. ISCO and EAB were presented as the preferred alternatives. The WDEQ approved the remedial approach in late 2006. In late 2007, a remedy implementation work plan (RIWP) was prepared providing design details of the remedial technologies. In early 2008, remedial activities were implemented.

During the ISCO remedial activities, a 3 percent aqueous sodium permanganate solution was applied within the source area at depths between 3 and 35 feet bgs. Approximately 500 gallons of 3 percent aqueous sodium permanganate solution was injected using direct-push methods at each of the 58 locations, with a total of 26,964 gallons of solution being applied.

During EAB remedial activities, a vegetable oil solution (CAP-18™) was injected within the groundwater plume at 5-foot depth intervals from 5 to 35 feet bgs. A total of 11 treatment curtains were injected during the EAB application. Approximately 3,142 gallons of CAP-18™ was injected at 195 locations.

Post-injection groundwater monitoring is ongoing to evaluate the effectiveness of the remedial activities. Initial post-injection results indicate significant contaminant reduction within the source area as groundwater concentrations have been reduced to non-detect. Further groundwater monitoring results are needed to properly evaluate the effects of the EAB application within the downgradient plume.