Project Coordinator and Member of Board of Directors
de maximis, inc.
Mr. Thompson has 26 years of experience managing the technical, administrative, and financial aspects of multi-party CERCLA site investigation and remediation projects. He has managed programs to delineate the nature and extent of non-aqueous phase liquids, solvents, metals, PAHs, PCBs and radionuclides in soil, sediment, and overburden and bedrock aquifers. Soil and sediment remedies managed have included excavation, in-situ and ex-situ thermal treatment, soil vapor extraction, capping, solidification/stabilization, bioremediation, and wetlands mitigation and restoration. Groundwater remedial experience includes natural and enhanced bioremediation, in-situ chemical reduction, phytoremediation, and ex-situ treatment. Site closure / removal actions managed have included drum excavations, UST/AST and lab material removals, asbestos abatement, and building demolitions. Mr. Thompson is a member of the Board of Directors of de maximis, inc., and currently serves as the Project Coordinator for the SRSNE, Nuclear Metals, Inc., Industri-plex OU2, and York Oil OU1 & OU2 CERCLA sites. He is a 1985 graduate of the United States Naval Academy.
SESSION KEYNOTE PRESENTER - Thermal Treatment: It's Cookout Time
In-Situ Thermal Remediation at the SRSNE Superfund Site
Solvents Recovery Service of New England (SRSNE) processed more than 100 million gallons of solvents between 1955 and 1991. Disposal to lagoons and other releases resulted in non-aqueous phase liquid (NAPL) zones in overburden and fractured bedrock. In-Situ Thermal Remediation (ISTR) of the overburden NAPL zone (estimated in the FS to contain 500,000 kg of VOCs within 36,000 m3) required a robust design and adaptive management.
Clean up levels were established based on reducing soil VOC concentrations to levels that were “not indicative of the presence of pooled or residual NAPL.” Key design aspects included developing drilling methods to minimize the potential for further downward migration of NAPL and selecting a robust vapor treatment system. The heated volume increased to 43,300 m3 due to NAPL found beyond the target area and installing heaters through weathered rock into the upper meter of competent bedrock. The VOC mass removal rate peaked at 4,500 kg/day. Higher than anticipated aromatic concentrations triggered modifications to the vapor treatment and monitoring system.
Clean-up levels were met in all samples (99.7% VOC removal from soils), although modifications to heaters and cover insulation were needed. Groundwater total VOCs decreased significantly during ISTR and two years of post-ISTR monitoring. A well installed into a former lagoon had the highest pre-ISTR TVOC concentration (598 mg/L), which dropped to 34 mg/L at ISTR completion (February 2015), and to 0.577 mg/L in July 2016. Pre- and post-ISTR qPCR microbial analysis each demonstrated strong dechlorinating populations, with a higher diversity post-ISTR.
225,000 kg VOCs were removed with ISTR, which combined with an estimated 170,000 kg removed from the ISTR zone through biodegradation during the time between NAPL delineation and ISTR, reasonably compares with the pre-treatment mass estimate.
At a time reasonably consistent with travel from the ISTR zone, influent TVOC levels in the downgradient hydraulic containment system dropped by a factor of four and chloride concentrations increased by a factor of five. These changes have persisted for the past 18 months (as have the post-ISTR groundwater temperatures above ambient); demonstrating a residual increase in biodegradation rate due to ISTR.