Innovations in Site Characterization. Case Study: Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

 Executive Summary

This case study describes a field analytical method that was used to measure PCB surficial contamination in empty drums to be cleaned by a new process. Approximately 7,000 empty 55-gallon drums that previously contained PCB-contaminated material had accumulated at the Department of Energy (DOE)’s East Tennessee Technology Park in Oak Ridge, TN. Because disposal of these drums following regulator-approved methods would have been very costly, DOE requested permission from the Environmental Protection Agency (EPA)-Region 4 to demonstrate the cleanup of these drums using a new CO2 scouring technology. DOE also proposed and EPA approved a sampling program to demonstrate the effectiveness of the clean-up technology and evaluate compliance with EPA’s regulatory limits for releasing PCB-contaminated items. The proposed sampling program consisted of (1) statistical control limits for process monitoring, (2) random sampling of processed drums, (3) wipe sampling of container surfaces, and (4) rapid analysis of the wipe samples by a field method.

While taking advantage of the cost effectiveness and quick turnaround of field methods, DOE minimized the risk of violating regulatory limits by selecting the field method based on the following criteria: (1) if field results are biased, they must be biased high, (2) the field technique should provide a low probability of false negative results, (3) the detection limit should be well below the lowest action/decision level, and (4) the field technique should provide quantitative results rather than results in the form of ranges or intervals. Of the six field methods evaluated during the Environmental Technology Verification (ETV) project co-sponsored by EPA and DOE, only the Dexsil L2000 PCB/Chloride Analyzer satisfied these criteria and was thus selected for monitoring the drum cleaning process.

During the initial phase of the project, the CO2 scouring technology vendor attempted to clean 20 of the most highly contaminated drums. The Dexsil PCB Analyzer was used to monitor residual PCB contamination in the processed drums during this trial period. Field analyses, completed and reported within one hour of sample collection, showed that the clean-up technology was not working as expected. On the basis of the field-generated results, which were confirmed by wipe samples sent to an off-site laboratory for gas chromatography analysis, DOE decided to abort the drum clean-up project before additional resources were expended. Although only a limited data set was obtained to evaluate the overall performance of the Dexsil field method, this case study demonstrates the usefulness of field methods for rapid decision-making.

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