Sigma installs vapor extraction remediation system



During construction of a drum storage room in 1989, solvent odors were detected inside the facility building. Through soil sampling and analysis, plant personnel confirmed the release of chlorinated and petroleum solvents. A trench was excavated to remove the accessible soil impacts. Subsequent investigation and remedial efforts were focused on addressing the source area and consisted of soil vapor extraction and groundwater pumping and treatment systems.

In 2004, The Sigma Group was retained as a subconsultant to assist in addressing the groundwater plume and off-site delineation. A thorough review of the existing database was completed and a pilot test was performed in 2005 to evaluate the effectiveness of vapor extraction/air sparging and enhanced bioremediation to address the groundwater impacts and position the site for closure.

Following Wisconsin Department of Natural Resources (WDNR) approval, a full-scale air sparge-vapor extraction remediation system was implemented using a network of 20 extraction / injection wells.


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Remedial activities provided by Sigma included:

  • Injection of bio-amendments through injection walls
  • Addition of oxygen via air sparging
  • Operation of soil vapor extraction system for controlling injected air

Post remediation sampling demonstrated over 90 percent mass reduction and establishment of natural attenuation. The WDNR has approved the case closure for the site based on substantial mass reduction and extensive post-remediation monitoring.