The requirements and standards for cleaning up a petroleum release are set by the Missouri Department of Natural Resources, (MDNR). State law requires those standards to be "risk-based," which simply means that the corrective action requirements must be based on an analysis of the risks posed by the petroleum to human health and the environment.

On December 29, 2004, Ed Galbraith, Director of the Hazardous Waste Program (HWP), issued a memorandum defining the "New Tier 1 Standards" which can be viewed in its entirety by clicking on this link.

In February 2004, the MDNR published an initial version of a Guidance Manual which outlines the requirements, MRBCA Process for Storage Tanks. This replaces three previous guidance documents - the 1996 Closure Guidance, the 1992 Site Characterization Guidance and the 1992 Corrective Action Guidance. Standardized forms for evaluating exposure pathways and analyzing risks are available at www.dnr.mo.gov/alpd/hwp/rbca-04-form.xls.

The MRBCA process applies to all media and all regulated petroleum storage tank sites, both aboveground and underground. Neither the person responsible for the tanks nor the MDNR can choose the media or sites to which this process will apply. However. during a transition period when sites that are close to receiving a No Further Action (NFA) letter from MDNR owners may complete cleanup under the old guidance. See "Technical Memo 1" for transition details.

MDNR will not require any additional evaluation of sites previously granted a NFA letter unless new information becomes available indicating the previous cleanup was incomplete, or there is a new release.

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