26-Acre Industrial Property
An ASTM/AAI Phase I ESA was performed on a 26-acre industrial property in Macomb, Michigan.
The following Recognized Environmental Conditions (RECs) were identified:
A portion of the subject property was formerly occupied by a farm hub and more recent historical uses included industrial operations such as tooling, machining, plating, and heat treatment and the use of hazardous substances and/or petroleum products, including used oils, coolants, and solvents.
Former machine pits were observed in the manufacturing area and existing pits were observed within the former heat treat area. Floor drains were located in the manufacturing areas and were connected to an oil water separator located outside of the manufacturing building.
Previous site assessment activities of the oil water separator documented solvent contamination in soils.
Interviews with knowledgeable site contacts indicated that a release had occurred in association with the storm water retention pond.
In addition, during the course of the Phase I ESA, it was determined that the subject property was formerly a Leaking Underground Storage Tank (LUST) site under Part 213 of PA 451. Previous studies related to the LUST were evaluated and it was determined that they met the criteria for closure under Part 213.
A Phase II investigation was designed and completed to address the identified RECs. Based on Phase II analytical results, additional investigation (Phase III) of soil, groundwater and soil gas was performed. The scope of work included 35 soil borings, 20 temporary monitoring wells, geophysical survey (Ground Penetrating Radar and a commercial grade metal detector) and 7 sub-slab soil gas points.
Analytical results indicated levels of volatile organic compounds (VOCs) in groundwater in an area within the building that exceeded the Michigan Department of Environmental Quality (MDEQ) volatilization to indoor air cleanup criteria for non-residential sites. A Sub-slab Depressurization (SSD) Pilot Study was then completed to evaluate the applicability of using a sub-slab depressurization system as a presumptive remedy to mitigate the potential for vapor intrusion from impacted groundwater beneath the subject building. However the pilot study determined that the radius of influence was very limited.
Remedial options (vapor barrier, passive/active venting, soil excavation/dewatering and calculation of soil gas/indoor air mixing zone) were evaluated to address the soil gas issue. Upon detailed evaluation of the proposed property use (industrial), characteristics of the soil gas plume (limited areal and vertical extent) and building design (volume of open areas, ceiling heights, condition and thickness of floor slab, presence of floor slab penetrations), it was determined that sufficient mixing would occur under all likely atmospheric and most building use conditions. A plan for response activities was developed that centered on maintaining industrial land use, and prohibiting the construction of habitable structures (offices etc.) in the area of the soil gas plume. The resulting deliverables included a Baseline Environmental Assessment (BEA) that was completed in accordance with the State of Michigan Section 20126(1)(c) of the Natural Resources and Environmental Protection Act (NREPA) 1994 PA 451 (PA 451), Part 201 as Amended, and the Rules promulgated thereunder. In addition, a Due Care Plan was completed in accordance with Rule 1003(5) of Section 20107(a) of PA 451, as amended, and the Part 9 Rules.