Beginning in 2015, the department began the process of revising and updating the Missouri Risk-Based Corrective Action (MRBCA) Rule and accompanying technical guidance document. The current update, revision and rulemaking pertains only to the MRBCA rule, departmental MRBCA technical guidance and Risk-Based Target, not the Tanks MRBCA technical guidance.

The MRBCA Stakeholder Workgroup, which includes representatives from the department, 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.

Public Notices/ Public Comments

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. 

Beginning in 2015, the department began the process of revising and updating the MRBCA rule and accompanying technical guidance document. The MRBCA Tier 1 Risk-Based Target Levels (RBTLs) used in the current technical guidance 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) updated the toxicity data for numerous chemicals. EPA also made changes to some of the generally applicable methods and equations used to develop its regional screening levels. The 2006 RBTLs were developed using some of the EPA data evaluation methods and equations. As a result, the RBTLs published in 2006 are out of date and need to be updated. The department also identified needed clarifications in the MRBCA guidance. The vapor intrusion exposure pathway also become an even more important aspect of site investigations, risk assessment and cleanup. In 2015, the department determined that a guidance revision is warranted.

The current update, revision and rulemaking includes the following efforts:

  • Revise the departmental MRBCA guidance document
  • Update the Tier 1 RBTLs found in Tables B-2 through B-10 of the departmental MRBCA guidance document
  • Amend Code of State Regulations 10 CSR 25-18.010 consistent with updating the target levels and revising the guidance

Updating the RBTLs will rely strongly on EPA methods and equations, as well as the EPA input values for toxicity and exposure factors. Updating the RBTLs is a cooperative effort between the Department of Natural Resources and the Department of Health and Senior Services (DHSS). The knowledge and expertise required to calculate target levels resides within the Department of Health and Senior Services, whereas the knowledge and expertise needed to appropriately apply the target levels resides within the Department of Natural Resources. These complimentary attributes are beneficial to this project and will help to ensure the resulting products are of the highest quality. This effort will ensure RBTLs are based on current science and are accurate, protective and defensible.

The departmental MRBCA guidance revision will involve correcting errors and inconsistencies, clarifying certain provisions, expanding on issues not adequately addressed in the 2006 guidance and eliminating redundant text and restructuring the guidance to improve its readability. In addition, the department proposes to address various specific technical issues associated with the guidance. Some of these issues – such as ecological risk assessment, hot spot identification and managing and collecting soil geotechnical data – will be addressed by the department, while others – such as updating the RBTLs, selecting chemicals of concern for risk assessment, evaluating cumulative risk and various vapor intrusion-related issues – will be addressed jointly by the Department of Natural Resources, the Department of Health and the MRBCA Stakeholder Workgroup.

Tanks MRBCA Revisions

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.
  • Jan. 8 , 2014: The department developed the Missouri Risk-Based Corrective Action Process for Petroleum Storage Tanks: 2013 Guidance Document Update - PUB2933 fact sheet to explain the differences between the 2004 Tanks MRBCA guidance and the 2013 updated guidance. 
  • 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.