Superior Environmental Corp (Superior), on behalf of a confidential Bay County, Michigan automobile dealership, was hired to investigate and close a used oil
underground storage tank (UST) release at the car dealership, originally reported in 1997.
The following remedial actions were performed:
- On September 29, 1997, two 1,000 gallon steel UST systems were removed from the ground.
- On December 2 and 3, 1998, approximately 394 cubic yards of impacted soil was excavated from the UST basins.
However, after the excavation, the site still contained soil and groundwater contamination, and used oil (LNAPL) was present in the soil and at several groundwater monitoring well locations. At the time (1998), the site could not be closed under existing Michigan Department of Environmental Quality (MDEQ) guidelines as the LNAPL impacts extended under the site building and there appeared to be few economical options for cleaning up and closing the site. To complicate things further, a wetland exists downgradient of the release, and multiple easements are present throughout the property. Theproject seemed to be at a standstill.
However, in 2014, the site was re-evaluated in light of the 2012 Amendments to Part 213 of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended (NREPA) and the relatively new (2013 and 2014) guidance documents from the MDEQ. The new guidance documents now allow sites with existing contamination and LNAPL that were not suitable for closure previously to pursue closure through a risk based corrective action (RBCA) process.
In 2014, after completing the delineation of soil, groundwater, and soil gas impacts, estimating the extent of mobile and residual LNAPL, and completing an exposure pathway evaluation using the RBCA process, a Final Assessment Report (FAR) was submitted to the DEQ to document the investigation and remediation phase. Based on the strategy presented in the FAR, on April 17, 2015, a Closure Report was submitted to the DEQ that would protect current and potential future site receptors, while allowing contamination, including the used oil (mobile LNAPL), to remain in the ground. The closure strategy was economically acceptable to the client and it would allow the car dealership to continue operating without interruption. The closure report utilized a Declaration of Restrictive Covenants filed with the county registry of deeds as a method of ensuring that site users would not come into contact with the contamination. The Restricted Covenant had the following restrictions to selected contaminated sections of the property:
- The site is restricted to non-residential use.
- The existing asphalt/concrete ground cover had to remain in place (or be replaced with something of equal protective value) to limit direct contact to the soil and
LNAPL, as well as to prevent rainwater from infiltrating through the contaminated soil.
- New buildings are restricted unless they have additional vapor intrusion investigations or presumptive mitigation.
- Groundwater use is restricted (the area is on municipal water supply).
- The reuse of contaminated soil is restricted.
On May 29, 2015, Superior received a letter from the DEQ of their intent to audit the Closure Report. On June 5, 2015, Superior received a letter from the DEQ notifying that the Closure Report had been approved. The client was elated to have the environmental liability for the release removed and to have the release removed from the MDEQ LUST list, which was holding up a property transaction.
In summary, this project is a good example of newer closure options available under Parts 201 and 213 in Michigan. Sites that have existing contamination, including LNAPL, that were not suitable for closure previously may be suitable now. The additional closure processes are in place, all the necessary guidance documents have been issued, and the MDEQ is eager to work with owners and consultants to close sites.
If you have a site that has not been reviewed in the context of the 2012 Amendments to Parts 201 and 213 of NREPA and the new guidance documents from the MDEQ, we recommend you contact Superior Environmental Corp, a Qualified Consultant, to see if there are any new closure opportunities.