As part of the EE/CA, a streamlined risk evaluation was conducted which evaluated all reasonably anticipated potential exposure pathways to contaminants of concern at the Site, and concluded that the magnitude and extent of contamination represented an unacceptable risk warranting a removal action.  Based on analytical data from the December 8, 2011 Waste Disposal Profiling Investigation Report, the material in the roll-off boxes contains hazardous substances including dioxins and a number of semi-volatile PAHs at concentrations greater than appropriate risk-based standards. Total dioxin and furan concentrations ranged from 10.3 to 108.4 µg/kg toxic equivalents (TEQs) in the roll-off boxes and 0.003 to 78.1 µg/kg in the IDW drums. Total dioxin concentrations ranged from 23.4 to 541 µg/kg TEQs in the berm soil. None of the chemicals of concern were detected at concentrations exceeding the Toxicity Characteristic Leaching Procedure (TCLP) criteria promulgated in 40 CFR § 261.24. Due to the passage of time, the condition of the roll-off boxes had deteriorated and could have potentially jeopardized the ability to secure the contents. If released into the environment, the contaminated waste materials might have migrated via airborne dusts, surface runoff to nearby storm water conduits and surface water, and via worker activity transporting soils/dusts onto otherwise unimpacted areas of the Site, vehicles, facility buildings and residences.

There have been a number of previous investigations at the Site. See the original Action Memorandum for the Site, available on the project website at http://www.epaosc.org/ThompsonChemicals, for a description of the previous investigations and a summary of the pertinent findings. On December 8, 2011, additional investigations were performed to determine whether the waste materials contained in the 12 roll-off containers and 238 drums were characteristically hazardous. None of the chemicals of concern were detected at concentrations exceeding the TCLP criteria promulgated in 40 CFR § 261.24. A December 8, 2011, Waste Disposal Profiling Investigation Report documenting the sampling activities and methods, analytical results, and findings and conclusions was submitted to the EPA and the Missouri Department of Natural Resources (MDNR). The EPA reviewed the Waste Disposal Profiling Investigation Report in conjunction with MDNR and issued a joint approval letter to the Respondents dated January 10, 2012.

In September 2012, sampling investigations were performed to determine whether the berm soil was characteristically hazardous. None of the chemicals of concern were detected at concentrations exceeding the TCLP criteria promulgated in 40 CFR § 261.24. A November 27, 2012, Berm Soil Waste Profiling Investigation Report documenting the sampling activities and methods, analytical results, and findings and conclusions was submitted to the EPA and MDNR. The EPA reviewed the Report in conjunction with MDNR and issued an approval letter to the Respondents dated December 17, 2012. 

The scope of this response did not warrant a structured incident management team (IMT), and there was no Logistics Section Chief or separate logistics section.

The PRPs and their primary contractors (SLR, Inc., and Environmental Restoration) were responsible for site safety.  Removal activities were conducted in accordance with a consolidated Site Health and Safety Plan, and daily health and safety briefings were attended by all on-site workers.  No safety incidents were reported.

The scope of this response did not warrant a structured IMT, and there was no Liaison Officer assigned.

The limited scope of this removal action did not warrant a Unified Command.

This is a Final POLREP.  No additional reporting is anticipated.