Remediation and Vapor Intrusion Services for Residential Area in the Village of Sparta, Michigan
A former gray iron foundry, located in the Village of Sparta, Michigan, had been in operation since the 1920s, where solvents and lubricating oils were used in the production of piston rings and other products. Gasoline, diesel fuel, and mineral seal oil were also stored at the site in underground tanks. Slag, foundry sand and grinding wastes had been disposed of on site. Previous investigations identified elevated concentrations of trichloroethylene (TCE) and tetrachloroethylene (PCE) in soil and groundwater samples exceeding the Michigan Department of Environment, Great Lakes and Energy (EGLE -formerly – MDEQ) criteria. This posed a potential vapor intrusion (VI) risk to nearby residences.
This area had undergone many previous investigations and remediation activities were completed by EGLE. Approximately 14,000 tons of contaminated soils were removed in 2012 and groundwater monitoring wells were installed. Monitoring wells and soil gas sampling results in 2015 verified VI was not a concern to the north or west of the source area. However, there was a potential VI risk in the residential area to the east and south.
AKT Peerless conducted remedial investigation activities to better define the horizontal and vertical extent of the known soil gas and groundwater contamination identified during previous subsurface investigations in the residential area near the foundry. These activities included groundwater plume delineation, soil gas sampling, sub-slab soil gas assessments and indoor air sampling at select residences to determine the potential risk from harmful vapors entering the residences. The results of the investigation would assist in designing and implementing remedial options, which would include vapor mitigation systems.
Soil gas results revealed a potential risk from harmful vapors entering two residences. AKT Peerless designed and installed two active sub-slab depressurization systems and sealed sumps in these residences. AKT Peerless also conducted performance monitoring of the systems to demonstrate effectiveness of the remedies, reported monitoring results to EGLE and provided operations and maintenance documentation to EGLE and affected homeowners.
AKT Peerless completed remedial investigation in the residential area and identified two structures where a VI concern was present. AKT Peerless designed and installed two (2) active sub-slab depressurization vapor mitigation systems (VMS). Performance monitoring verified the VMS were effective in meeting performance objectives that allow for the continued safe occupancy of the buildings. The indoor air quality was tested and determined to be safe for the residences (after the installation of the vapor mitigation
systems). AKT Peerless developed operation and maintenance plans for the systems.
