Potential for Change in “Best” Practices for Phase II ESA Investigations

Aug 09, 2022

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In 2021, the Michigan Department of Environment, Great Lakes, and Energy (EGLE) along with Leslie DeBoer of BLDI presented a webinar discussing site characterization and mitigation for acute vapor hazards caused by leaking underground storage tank (Part 213) sites.

EGLE has indicated that a similar guidance for all contaminated properties (currently regulated under Michigan’s Part 201) is in development. EGLE has indicated that the Part 201 guidance will likely be similar to the Part 213 guidance. It is BLDI’s opinion that, although no timeline has been provided on when this guidance would be available, this Part 213 VI addendum should be applied in the same way for 201 sites in the meantime. Based on this new guidance, the customary, limited Phase II Environmental Site Assessment (ESA) investigations conducted in Michigan will need to be revisited with respect to meeting “All Appropriate Inquiry” (AAI).

Current Vs. Future “Best” Practice

The level of site investigation and characterization is largely determined by the concerns identified by a Phase I site assessment, the overall goal of the investigation, and the Client’s risk tolerance. Frequently, Phase II investigations are of limited scope, especially in Michigan, primarily as a cost-saving measure. Soil gas (i.e., vapor) may not be sampled during the Phase II investigation. However, based on the now-issued guidance from EGLE, additional site characterization may be necessary for some sites in order for the owner to qualify for the various liability protections. This minimalist Phase II approach (sometimes called a “Skinny BEA” investigation) has inherent risks for a purchaser, especially for “clean” Phase II ESAs with a limited number of sample locations and analytes.

Remember, liability protections available under AAI assume that the owner had no reasonable way to know about contamination. Was the Phase II scope that was completed adequate to truly meet that assumption? Or was the Phase II scope of investigation too narrow, and contamination that may have reasonably been found missed? Were all the appropriate analytical parameters tested for and were samples collected from logical places?

Owners can fail to qualify for liability protections established under CERCLA[1] if either proper site assessment wasn’t completed prior to ownership or if proper steps have not been taken to ensure no unacceptable exposures are present at the Property (known as “continuing obligations”).


Overall, based on the issuance of this guidance for Part 213 sites and the understanding that similar guidance will be issued for Part 201 in the future, the responsible course of action appears to be revisiting what is considered an “appropriate” and sufficient amount of site characterization during a Phase II investigation.

[1] Comprehensive Environmental Response, Compensation, and Liability Act (1980)