Barr has provided groundwater-monitoring network design, data review, and statistical analysis for Heskett Station’s coal ash landfill since 2010. When the U.S. EPA administered the Coal Combustion Residuals (CCR) Rule in 2015, we developed a compliance monitoring strategy, made network improvements to meet rule requirements, and instituted statistical analysis protocol for data evaluation. Since the rule took effect, Barr’s use of statistical methods, forensics, and institutional knowledge of the site geology and historical groundwater conditions has helped the client avoid costly corrective-action measures by determining that the parameters of concern were previously observed at elevated concentrations in soil and groundwater prior to construction of the coal ash landfill.
Barr developed and tested a “multiple working hypothesis” method to make an alternative source demonstration that documented lines of evidence showing that current observed conditions were consistent with historically elevated concentrations. We have since used this method to make several alternative source determinations under the CCR Rule, which has helped our client avoid unnecessary and costly action to remediate groundwater under the rule. In addition, Barr’s experienced data-quality-assurance team identified laboratory and sampling inconsistencies, which provided additional evidence that the downgradient detections were false positives.