Missouri Risk-Based Corrective Action (MRBCA) Revision Information
In 2015, the department began initial efforts to:
Update the Tier 1 Risk-Based Target Levels (RBTLs) found in Tables B-2 through B-10 of the Missouri Risk-Based Corrective Action (MRBCA) guidance document
Revise the MRBCA guidance document
Amend Code of State Regulations 10 CSR 25-18.010 consistent with updating the RBTLs and revising the guidance
The update, revision and rulemaking pertain only to the Departmental MRBCA RBTLs, guidance and rule, not the Missouri Risk-Based Corrective Action Process for Petroleum Storage Tanks (Tanks RBCA) guidance document. Revisions to the departmental MRBCA technical guidance were delayed for a variety of reasons, including the COVID pandemic, organizational restructuring with the department and staff turnover at the Missouri Department of Natural Resources and the Missouri Department of Health and Senior Services.
The MRBCA Stakeholder Workgroup, which includes representatives from the Department of Natural Resources, consultants, industry groups and partner agencies, met to hear from the user community. The workgroup also reviewed and provided comments on the department’s list of proposed updates and revisions and a draft of the revised guidance document.
There are no currently active MRBCA Revision Public Notices/ Public Comments.
Departmental MRBCA Revisions
The April 2006 Departmental MRBCA technical guidance document was updated in June 2006 and June 2008. Information about any additional updates, revisions and rulemaking will be provided below when they become available.
Current Updates
The MRBCA Tier 1 RBTLs were initially published in June 2006, and developed based on data and methods in place at that time. Since then, the U.S. Environmental Protection Agency (EPA) has updated toxicity data for numerous chemicals. EPA also made changes to some of the generally applicable methods and equations used to develop EPA's regional screening levels (RSLs). The 2006 RBTLs were developed using some, but not all, of the EPA data evaluation methods and equations.
This update of RBTLs relies on EPA current methods and equations, as well as the EPA input values for toxicity and exposure factors. As a result, the updated RBTLs will be much more consistent with EPA RSLs. However, the RBTLs for carcinogenic chemicals will be based on an individual excess lifetime cancer risk (IELCR) level of one in 100,000 (1x10-5) rather than the one in one million (1x10-6) IELCR level used by EPA. This effort will ensure RBTLs are based on current science and are accurate, protective and defensible. Updating RBTLs also is consistent with the department’s intention to periodically revisit and revise MRBCA guidance to ensure the document remains current, as discussed in Appendix A of the guidance.
The MRBCA guidance revision corrects historical errors and inconsistencies, clarifies certain provisions, expands on issues not adequately addressed in the 2006 guidance, eliminates redundant text and is restructured to improve readability. Certain issues in the updated guidance were updated by the department’s Environmental Remediation Program (ERP), such as ecological risk screening/ assessment, hot spot identification and management and collection of soil geotechnical data. Certain other issues were updated by ERP in coordination with the Department of Health, with consideration of the MRBCA Stakeholder Group comments previously received on initial draft updates to the guidance. This includes issues such as updating the RBTLs, selecting COCs for risk assessment, evaluating cumulative risk and various vapor intrusion-related issues.
Updating the RBTLs was a cooperative effort between the Department of Natural Resources and the Department of Health. The Department of Health had the main knowledge and expertise to calculate the updated target levels for risk assessment purposes. The Department of Natural Resources had the knowledge and expertise needed to appropriately apply the target levels for risk management. These complimentary functions help to ensure the updated guidance is useful for both risk assessment and risk management.
As part of the MRBCA update process, the Department of Health is preparing software that can be used in Tier 2 and Tier 3 assessments when changes to default assumptions are proposed by eligible Brownfields/ Voluntary Cleanup Program facilities. This software will be made available on this webpage when completed. The draft updated RBTLs and associated tables of input parameters and equations will be available as part of the revised guidance.
For questions regarding the RBTL update, guidance revision, rulemaking project, please contact the Department of Natural Resources' Brownfields/ Voluntary Cleanup Program at 573-526-8916 or by email at MissouriBrownfields@dnr.mo.gov. To receive MRBCA update email notifications, please use the green “Get Updates on this Issue” button on this webpage.
Tanks MRBCA Revisions
Currently there are no update, revision or rulemaking efforts taking place pertaining to Tanks MRBCA.
The 2004 Tanks MRBCA technical guidance document was modified in March 2005 and updated in October 2013. Information about any additional updates, revisions and rulemaking will be provided below when they become available.
Nov. 6, 2009: The department issued an errata notice regarding Appendix D of the 2004 technical guidance. The 2009 Errata Notice pertained to an incorrect conversion factor, which was corrected in the 2013 technical guidance.
June 3, 2011: The department issued an errata notice regarding Table 4-1, Soil Concentration Levels to Determine the Need for Groundwater Evaluation During Tank Closure, of the 2004 technical guidance. The 2011 Errata Notice pertained to incorrect target levels in the table for TPH-GRO, TPH-DRO, C6-C8 Aliphatics, C8-C10 Aliphatics, C10-C12 Aliphatics and C12-C16 Aliphatics.
Sept. 17, 2013: Under the tanks MRBCA process, activity and use limitations (AULs) may be used as part of a corrective action plan to address risks associated with a petroleum storage tank release. To promote consistency and efficiency in applying AULs, the department developed model AULs and one- and two-party restrictive covenants.
Oct. 17, 2013: The Hazardous Waste Management Commission gave final approval to the department’s amendments to Code of State Regulations 10 CSR 26-2.062, 26-2.078 and 26-2.082 and the updated Tanks MRBCA guidance document. The guidance update included changes to the Tier 1 Risk-Based Target Levels (RBTLs). The rule amendments were necessary to, in part, incorporate the updated Tanks MRBCA guidance into rule by reference. The amended rules became effective Feb. 28, 2014.
May 29, 2015: The department issued an errata notice pertaining to Figures 2-1 and 2-2 of the 2013 technical guidance. The 2015 Errata Notice pertained to the department inadvertently omitting the figures.
