Groundwater Containment Interim Action

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Groundwater Containment Interim Action

Historical operations at a rubber manufacturing facility resulted in impacts of chlorinated VOCs in bedrock groundwater. At the time the impacts to bedrock groundwater were discovered, very little information was known about the local hydrogeology. Cox-Colvin developed an expedited approach to evaluate regional hydrogeology, install onsite and offsite monitor wells and perform aquifer testing. Based on the results of this effort, it was apparent that an interim action was necessary to prevent the continued offsite migration of chlorinated VOCs until the source areas could be identified and remediated.

Cox-Colvin performed three-dimensional groundwater flow modeling to determine the optimal number, placement, and pumping rate of wells to achieve onsite containment of the groundwater plume. An evaluation of remedial technologies by Cox-Colvin determined that the most cost effective approach for treatment of the extracted groundwater from the containment wells was through an air stripper. A permit-to-install (PTI) from the state agency was necessary to construct the groundwater containment and treatment system. Through negotiation with the state, the PTI was used as an innovative tool to require the facility to identify and remediate source areas. By stipulating these requirements within the PTI, the facility was able to avoid the issuance of an Order.

The system consists of two containment wells pumping at a combined rate of approximately 35 gpm and an air stripper housed within the facility building. Cox-Colvin incorporated telemetry into the system to allow for continuous monitoring of operating parameters and notification in the event of an alarm condition.

Since startup, Cox-Colvin has performed routine O&M activities on the groundwater containment and treatment system. Whenever possible, Cox-Colvin has identified and implemented system optimization measures to reduce the environmental footprint of the system, including reducing annual O&M costs. The system continues to operate as designed by preventing the offsite migration of chlorinated VOCs. Subsequent source area remediation has significantly reduced VOC concentration in groundwater and treatment requirements.