Clinton County is the fastest growing county in Michigan, growing by over 15% in the last 10 years. To help continue that growth, the F.C. Mason Company (FC Mason) purchased a vacant, 265,000 square-foot former manufacturing plant in St. Johns to redevelop into a new headquarters and primary production facility for its expanding agricultural implement manufacturing operations. At completion, the project added, created and/or retained over 100 high-wage jobs in this rural community north of the state’s capital city.

Used for over 60 years for manufacturing automotive bushings and bearings, the plant stood vacant after its owner ceased operations on the site in 2008. Trichloroethylene (TCE) and lead were the primary residual contaminants, with TCE vapor intrusion (VI) into the building at levels posing a threat to occupants being the major barrier to reuse. The first challenges were assessing the extent of the VI threat and finding money to pay for the VI mitigation. SME’s Environmental Team used money from an EPA Brownfields Assessment Grant that SME secured for Clinton County to conduct an extensive subslab soil gas investigation, which revealed the VI risk extended beneath more than 90% of the building. The investigation included evaluations of temporal changes in soil gas concentrations and comparing the results from soil gas screening techniques and formal collection and laboratory analysis of samples. SME’s Community Development Team then secured a $1 million state brownfield redevelopment grant to design and install a VI mitigation system.

The former owner had removed over 7,000 square feet of the plant floor lying above the largest TCE source area and had attempted to chemically reduce the contaminant concentrations. The new owner wanted to use the space for storage of steel raw materials, but the resulting soil in this area was poorly compacted, wet, and had low bearing capacity. Since a key part of preparing the plant for reuse was capping this large source of vapor into the building, and the future use would involve heavy loads, SME’s multidisciplinary project team of environmental, geotechnical, and pavement experts went to work developing soil stabilization, concrete floor replacement, and excess contaminated soil management strategies. Then the team prepared detailed engineering drawings, design plans and specifications, and bid documents. SME retained contractors to remove enough contaminated soil to provide room for soil stabilization, construct an engineered base for the new floor, and install a new, heavily reinforced floor. Excavated soil was used to fill trenches and pits before capping with new concrete to level the floor; excess soil was properly disposed. A special epoxy coating was then applied to over 20,000 square feet of floor in the area of highest subsurface contamination levels to prevent vapor intrusion. SME’s Construction Materials Services team monitored construction and verified compliance with project specifications.

Prior to FC Mason’s acquisition of the site, SME’s Environmental Team conducted Phase I and Phase II environmental site assessments and prepared appropriate reports and plans to secure protection from liability for cleanup of the site and document the VI mitigation other approaches used to ensure safe future use of the site. SME also prepared a site-specific health and safety plan for the project, tracked the sources and uses of brownfield funding, and helped the county manage the federal and state brownfield grants for the project.