In the upcoming weeks, the Michigan Department of Environmental Quality (DEQ) will be releasing new policy and procedures guidance document relative to the latest changes to Part 213, as it relates to the assessment of UST sites where Light Non Aqueous Phase Liquid -LNAPL (previously known as free product) is present. The guidance will affect site investigations and closure at all Leaking Underground Storage Tank sites, regardless of whether LNAPL has been observed in the past or not. The following presents a very brief summary of the new policy:
Previously, product abatement was considered complete when the thickness of LNAPL present in ALL monitoring wells at the site remained less than 1/8 of an inch over a 12 month monitoring period. Under the policy currently being considered, the thickness of LNAPL in a well will have less relevance since it is understood that the simple presence of measurable LNAPL does not indicate that an unacceptable risk will occur.
The new policy is expected to require that all 'recoverable' LNAPL be removed as long as recovery can be conducted in a cost effective and efficient manner. Continued abatement may not be necessary at sites where recovery is significantly diminished and closure is prevented only by the periodic reoccurrence of LANPL in a well.
The new policy is expected to allow site closure with measurable LNAPL remaining, provided: 1) all "recoverable" LNAPL has been removed, 2) the remaining LNAPL body and groundwater plumes have been completely delineated and are determined to be stable, 3) all risks posed by the remaining LNAPL body are acceptable, 4) all contaminant exposure pathways (water, air, LNAPL) are eliminated or not relevant, and 5) institutional controls are implemented to prevent unacceptable changes in site conditions or land use that could cause new exposure or increase risk and to notify future owners of the presence of LNAPL.
Envirologic continues to monitor the development of this issue and will provide a more thorough update once the new guidance document is released and available for comment. Please do not hesitate to contact any of our professional staff regarding questions on the new LNAPL policy and procedures. Stay tuned!
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mdeq • michigan department of environmental quality • ust • underground storage tank removal • underground storage tanks • part 213 • lnapl