Containment and Remediation of Organic Chemicals in Groundwater in Emergency Response Scenario
A tank farm fire and explosion occurred at a permitted treatment, storage, and disposal facility (TSDF), which resulted in the release of liquid organic wastes to a nearby storm water retention pond. The pond was unlined and provided a direct vertical pathway to the regional Sole Source Aquifer. As such, the contaminants that entered the pond quickly migrated through the vadose zone sand and gravel into groundwater. Emergency response was necessary to protect downgradient groundwater receptors.
Within three days following the fire and release, all flow into the basin was blocked and Cox-Colvin performed two-dimensional groundwater modeling to determine the location and combined pumping rate from recovery wells necessary to capture groundwater. Four high capacity recovery wells were installed and operating within a week of the incident. Extracted groundwater was treated using a Cox-Colvin water treatment trailer. Contaminated sediment was excavated from the pond. Vadose zone soil beneath the pond was remediated by the direct application of sodium permanganate into the pond, and recirculation of the oxidant with extracted groundwater.
Periodic sampling of the extracted groundwater indicated that all contaminants were below detectable levels after approximately 14 days of recirculation and periodic application of sodium permanganate. Following the completion of recirculation activities, soil cores were collected beneath the footprint of the pond to confirm that residual contamination within the vadose zone was adequately remediated, with no further action required. Fence-line monitor well directly downgradient of the pond were routinely sampled throughout and following remedial activities and demonstrated the successful containment and cleanup of groundwater prior to leaving the site.