BETA conducted a limited subsurface investigation to determine the environmental integrity of the cesspool that historically received floor drainage from within the service garage as well as sanitary wastewater. The initial investigation included sampling of the sediments contained at the bottom of the cesspool. The concentration of Total Petroleum Hydrocarbons was determined to be above its GB Leachability standard and the concentration of total lead was above its Industrial/ Commercial Direct Exposure criterion. The concentration of leachable lead (TCLP) was also detected above the threshold defining a hazardous waste.
BETA prepared an Underground Injection Control system closure application and an evaluation of remedial actions to address contamination at the site. Based upon the site conditions discussed above, the recommended action was to stabilize the hazardous concentrations of lead and dispose of the contaminated soil at an appropriate off-site disposal facility.
Approximately 100 tons of contaminated soil was mixed in-situ with 20 cubic yards of Soil Solutions Treatment Technologies – Calcium Sulfate, which is an encapsulating/stabilizing agent used to declassify the hazardous leachable lead. The concentration of leachable lead from the stabilized soil was below the laboratory detection limit and the soil was disposed at the Cranston Sanitary Landfill.
To assess groundwater conditions, three 2-inch diameter groundwater monitoring wells were installed in proximity to the former cesspool to a depth of 10 feet below the groundwater table. Following proper well development and purging, groundwater from each well was sampled and analyzed for VOCs, TPH, and RCRA 8 metals. No constituents were detected at concentrations above their respective regulatory thresholds.
Since some residual soil contamination likely remained beneath the site building, BETA developed a Soil Management Plan and an Environmental Land Usage Restriction that were filed in the Land Evidence Records of the Town of Cumberland.