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IDEM Revisions to Total Petroleum Hydrocarbon Procedures for Ground Water Could Significantly Impact Petroleum Remediation Site Closures


On June 17, 2010 the Indiana Department of Environmental Management (“IDEM”) released revised procedures for addressing Total Petroleum Hydrocarbons (“TPH”) in ground water at petroleum remediation sites. Based on conclusions and recommendations of the IDEM Risk Integrated System of Closure (“RISC”) TPH Workgroup, IDEM has determined that the routine delineation of TPH in ground water is no longer warranted at many remediation sites. The revised procedures could significantly affect the scope and expense of required investigation and remediation of sites with ground water impacted by refined petroleum products including gasoline, mineral spirits, Stoddard solvents, diesel fuel, and waste oils.

In order to implement these procedural changes, IDEM has discontinued the default TPH closure levels for ground water summarized in Chapter 8 of the RISC Technical Resource Guide. This change means TPH in ground water is no longer a constituent of concern at IDEM remediation sites with refined petroleum product contamination. Sites held up from obtaining regulatory closure because of TPH in ground water may now be eligible for closure without incurring significant remediation expenses. In addition, sites that previously obtained regulatory closure through the use of an Environmental Restrictive Covenant to address TPH in ground water may be eligible to have the use restrictions eliminated or reduced. Finally, measurement of TPH in ground water will no longer be routinely requested by IDEM project managers during site investigations and remedial monitoring unless TPH analyses are necessary to determine if municipal or private drinking water wells are affected by a petroleum release. Where a drinking water well may be impacted, IDEM remediation program project managers will have the discretion to require ground water TPH measurements.

At this time, IDEM’s procedures applicable to TPH in soil, including default closure levels and site characterization and remediation requirements, remain unchanged. Interested parties should be aware that IDEM indicated in the June 17, 2010 announcement that it is considering an expansion of the petroleum constituents of concern list and changes in how exposure pathways are evaluated at petroleum remediation sites.

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