Theme: 04. Addressing Challenging Site Conditions

Topic Area: 4a. Adaptive Site Management: Lessons Learned for Site Characterization and Remedy Implementation

Formatted Title:

Remedial Process Optimization for Accelerated Site Closure

Background/Objectives:

Ongoing investigation and remedial action have occurred at a site in southern Georgia that is managed under both the Resource Conservation and Recovery Act (RCRA) as well as the Georgia Hazardous Site Response Act (HSRA). Corrective action at the site has been ongoing for more than 35 years and includes site delineation, excavations of multiple solid waste management units (SWMUs), groundwater extraction and treatment through an on-site groundwater treatment system (GWTS), routine groundwater monitoring and reporting, and routine post closure care for capped regulated units. The property owner’s desire to sell the property has driven an accelerated approach for remedial activities to ultimately exit the RCRA and HSRA programs on an expedited timeline, saving an estimated 15 years and more than $5.5 million, during which sale of the property would have been prohibited, or severely inhibited until such time that original remediation goals were met.

Approach/Activities:

After coordination and communication with the Georgia Environmental Protection Division (EPD), a multifaceted approach was developed to facilitate expedited corrective action for both groundwater and soil. The approach focused on allowing the aquifer to return to natural flow conditions without off-site contaminant plume migration, and to ensure remaining impacted soils at the site were removed. To achieve these goals simultaneously, several regulatory steps that are commonly followed sequentially were pursued concurrently wherever possible. These tasks included: pursuit of a RCRA temporary authorization (TA) to inactivate the GWTS to allow the aquifer to return to natural flow conditions; coordination with EPD to develop risk-based site-specific remedial goal options that consist of maximum contaminant concentrations that meet standards for both the RCRA and HSRA programs for soil and groundwater; pursuit of a second TA to allow for penetration of a regulated unit cap to refine soil delineation and perform in situ stabilization and removal of impacted soil from a regulated unit; development of a corrective action implementation report (CAIR) certifying that corrective action was conducted in accordance with the approved TA; collection of groundwater samples post-GWTS inactivation to confirm that off-site groundwater concentrations are below Maximum Contaminant Levels (MCLs); and development and execution of a Uniform Environmental Covenant (UEC) to restrict groundwater use within the property boundary for non-remedial purposes.

Results/Lessons Learned:

Corrective action was completed by utilizing TAs to temporarily deviate from the site’s RCRA permit and operate within approved 180-day windows. EPD’s cooperation in developing the path forward and approval of the proposed approach demonstrate the EPD’s willingness to expedite site closure where possible by implementing several concurrent actions. As a result, all soils above the site-specific remedial goals have been removed, the GWTS has been inactivated with no indication of contaminant plume migration beyond the property boundary, and a UEC will be executed restricting site groundwater use, thus mitigating the risk to human health and the environment and making the site applicable for permit termination. Future remediation activities, anticipated to consist only of limited groundwater monitoring, will be managed through an agreed open administrative order. These activities will be described, and details of the process described above will be presented.

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Brent Callihan