ACE mobilized equipment to pump, clean and remove an underground heating oil tank. The home owner had stated that it was likely that the oil tank had leaked as vapors were present in the home.
The UST was properly removed under the direction of an ACE-employed MDE certified technician. During removal multiple perforations were observed in the UST and evidence of impacted soil was apparent. Impacted soils were stockpiled on site for proper disposal.
During excavation activities, a black drainage pipe was encountered and approximately seven gallons of oil were released into the excavation. Oil was removed with sorbent pads and the excavation continued but was limited by the reach of the machine and the close proximity of the building. A tee was placed on the drainage pipe and the pipe was extended (vent) above the surface so that the excavation could be backfilled.
This also allowed for the installation of the new aboveground oil tank and elimination of safety concerns regarding an overnight open excavation. During excavation activities, vapors in the home subsided, however once the excavation was closed vapors returned. The MDE directed that the stormwater drainage system needed to be flushed to remove residual LPH in the system.
A flush was conducted by accessing the vent pipe and recovering water/LPH from the drainage pipe. The flushing of the vent had a secondary effect to remove vapors. During the extraction process, vapors in the house subsided. Since impacts remained in place (likely below the level of the drain pipe), a vapor recovery system was placed on the vent to remove vapors from beneath the house and prevent vapor migration into the house.
Although soil sampling results (post excavation) exceeded the MDE standards, based on the engineering controls placed on the house (vapor removal system), soil was removed to the extent feasible, and the fact that the home was serviced by public water and sewer, the MDE closed the case.
ACE assisted the home owner with preparation of the MDE reimbursement application for cost recovery related to the discovered impacts.