RFI and CMS at Commercial TSDF
RCRA Corrective Action began at this active, commercial hazardous waste TSDF and Class I deep well injection site, in 1989 with the identification by EPA Region 5 of 72 SWMUs. The facility, located in the Midwest, once served as an oil and waste disposal site. The facility was ranked as a high priority site under NCAPS. The requirement to implement a RCRA Facility Investigation (RFI) was included in the facility’s federal hazardous waste permit. A nationwide consulting firm was hired to implement the RFI. After completing the first phase of the RFI, the facility contracted Cox-Colvin to complete Corrective Action. As a starting point, Cox-Colvin recommended the facility revisit the RFI scope of work to remove the requirements for further investigation of over 20 regulated units which were clean closed through the state’s RCRA authority, and to recalculate background limits for soil. The requirement to investigate the many clean closed regulated units was eventually dropped when the state gained primacy for its RCRA Corrective Action program.
During Phase II of the RFI, Cox-Colvin developed realistic background limits for soil, sediment and surface water; determined the nature and extent of contamination for all remaining SWMUs; and conducted a baseline ecological risk assessment. Constituents of concern included VOCs, SVOCs, herbicides, pesticides, PCBs, dioxins, and metals. Multiple lines of evidence were used to eliminate the leaching to groundwater pathway. The human health risk assessment was then able to focus on commercial/industrial exposure to soil, sediment, and stabilized waste, and concluded the need for remedy evaluation, through a Corrective Measures Study (CMS) at 9 units. Cox-Colvin then conducted a focused CMS which incorporated green and sustainable remediation concepts into the final evaluation of potential remedial alternative. As part of the CMS, Cox-Colvin utilized surface geophysics to define the extent of stabilized waste over large areas. Through frequent communication with the state agency throughout the CMS, the CMS report was approved without comments.