Sigma system assists printing facility with vapor extraction

Michigan Upper Peninsula

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Petroleum solvents used in the printing process were released from a facility storage system. Although the source of the release had been removed from the site, continued facility operation and infiltration of rain water through the source area continued to feed an expanding groundwater plume. The presence of free phase solvent was also observed in the source area monitoring wells. The Sigma Group proposed a multi-system remediation strategy consisting of a vapor extraction and off-gas treatment system, and an enhanced bioremediation system for soil vapor and groundwater. Following source area delineation, a remedial system was installed consisting of the following components:

  • Impermeable cap over the source area to prevent surface infiltration and limit contaminant migration from source soil to groundwater.
  • Operation of vapor extraction system using network of 18 extraction wells within former source location and inside the facility building to address relatively high concentrations of volatile constituents present within subsurface.
  • Off-gas from extraction system was conveyed to the facility air treatment system for thermal oxidation and contaminant destruction prior to discharge to meet State emission requirements.
  • Address high degree of groundwater impacts by enhancing partitioning of dissolved constituents to the vapor-phase via operation of vacuum extraction system.
  • Installed a series of downhole molecular oxygen diffuser systems (iSOC) to deliver high concentrations of dissolved oxygen in groundwater and periodic addition of naturally occurring bacteria (CL Solutions Petrex®) to augment subsurface microbial population and promote rapid degradation of dissolved contaminants.

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Sigma mobilized its trailer-mounted remediation system to the site and initiated vapor extraction and enhanced bioremediation of impacted soil and groundwater at the water table interface. The extraction and treatment system operated continuously to address vados zone contaminants while the groundwater enhanced bioremediation system addressed the dissolved groundwater plume.

The downhole molecular oxygen diffuser (iSOC) systems installed within several monitoring / remediation wells continued to provide a high degree of Dissolved Oxygen in groundwater (40 ppm to 70 ppm). Periodic addition of naturally occurring bacteria within subsurface environment with enhanced DO concentrations allowed rapid growth of bacterial populations and resulted in rapid aerobic degradation of dissolved constituents. Concentrations of dissolved petroleum constituents decreased by three orders of magnitude in the original source area and concentrations at locations downgradient of the source area are approaching cleanup levels.

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