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IDEM Announces Significant Revisions of Draft Remediation Closure Guide

12.01.2011

During the Indiana Department of Environmental Management’s (“IDEM”) October 25, 2011 quarterly Consultant’s Day program, IDEM announced that the May 6, 2011 Draft Remediation Closure Guide (“Draft RCG”) will be significantly revised in response to public comments. Public comments received by IDEM regarding the Draft RCG are available for review at http://www.in.gov/idem/files/remediation_closure_guide_comments.pdf. According to staff, IDEM intends to respond to all public comments in writing and to make a revised Draft RCG available for public review prior to the document being presented to the Solid Waste Management Board (“SWMB”) for adoption as a non-rule policy document. IDEM anticipates making the following revisions to the Draft RCG:

  • Plume Evaluation – IDEM received significant comments indicating that the plume evaluation process set forth in Section 4 of the Draft RCG will not work effectively. IDEM intends to revise Section 4 to eliminate the proposed plume evaluation matrix while retaining the Lines of Evidence (“LOE”) provisions.
  • Background – IDEM intends to place greater emphasis on LOEs while de-emphasizing the results of background concentration calculations.
  • Surface Soil – Due to difficulties in adequately defining surface and subsurface soils, IDEM intends to abandon the definition of surface soils set forth in the Draft RCG and instead focus on the analysis of soil direct contact risks regardless of depth based on professional judgment and LOEs.
  • Vapor – IDEM intends to revise Section 5 of the Draft RCG regarding vapor intrusion assessments to be less conservative including revisions of requirements related to attenuation factors and passive sampling techniques.
  • Screening Levels – IDEM intends to abandon the proposed screening level tables provided in the Draft RCG and will base all screening levels on the U.S. EPA’s Regional Screening Level tables. IDEM staff indicated that the U.S. EPA tables will be modified where necessary and will recalculate all screening levels using a 10-5cancer risk slope factor. Due to this anticipated revision, the following significant changes will occur from the screening levels provided in the Draft RCG:

    a. Recreational Screening Levels – According to IDEM, the U.S. EPA does not calculate recreational screening level tables and the revised Draft RCG will not include recreational screening levels. However, IDEM will recommend use of the U.S. EPA recreational screening level calculator with suggested parameters for certain recreational use scenarios.
    b. TPH Screening Levels – According to IDEM, the U.S. EPA does not calculate TPH screening levels for soil or groundwater. Therefore, IDEM staff indicated that the revised Draft RCG will not include screening levels for TPH.
    c. Industrial Groundwater Screening Levels – According to IDEM, the U.S. EPA does not calculate industrial groundwater screening levels. Therefore, IDEM staff indicated that the revised Draft RCG will not include industrial groundwater screening levels.

In order to provide time to incorporate the anticipated revisions of the Draft RCG as well as respond to all public comments, IDEM intends to delay presenting a revised Draft RCG to the SWMB until February 2012. IDEM staff did not provide any specific information regarding when written responses to public comments or the revised Draft RCG will be available for public review. Interested parties with questions regarding the anticipated revisions of the Draft RCG should contact Mike Habeck, IDEM Office of Land Quality at 317-234-4791 or mhabeck@idem.in.gov.

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