Soil Excavation

Former retail fueling station and market owner

Soil and groundwater impacted with unleaded gasoline constituents were located on-site and had migrated off-site beneath Pennsylvania State Route rights-of-way (ROWs) and a private property.  An aggressive soil and groundwater remediation strategy to attain the applicable PADEP Used Aquifer Residential Statewide Health Standards (UARSHS) Medium-Specific Concentrations (MSC) involved the operation of a Total Phase Extraction (TPE) system, an off-site supply well treatment system, on-site soil excavation, and off-site soil excavation within the ROWs and private property.

Remediation activities conducted on-site for the initial three years were successful in removing impacted soils and remediating groundwater.  However, recalcitrant petroleum impacts remained at a portion of the perimeter of the on-site soil excavation, beneath the off-site ROWs, and beyond to an off-site private property.  Therefore, an additional (off-site) soil excavation was completed adjacent to the on-site soil excavation, through the State Route ROWs after considerable coordination and permitting with PennDOT, and the off-site private property.  The excavation was completed in accordance with a PennDOT-approved detour plan (traffic control plan), a Highway Occupancy Permit, and a Right of Entry (ROE) Agreement; a ROE Agreement was also necessarily secured for access to the private property.  The soil excavations removed unsaturated and saturated soils approximating 444 cubic yards on-site and 1,385 cubic yards off-site. The soil excavations were designed to remove residual impacts to unsaturated soils and saturated soils in order to achieve soil attainment and accelerate remediation of groundwater impacts.  Following removal of impacted soils during soil excavation events, post-excavation attainment soil samples were collected via PADEP’s Systematic Random Sampling Protocol.  In total, the TPE system extracted, treated, and discharged approximately 1,067,065 gallons of groundwater.

Site closure with a Relief of Liability via a PADEP-approved Remedial Action Completion Report was achieved.  Based on the adjacent soil excavation extents and the cumulative results of soil attainment samples from both excavations, soil attainment was demonstrated.  Based on eight quarters of post-excavation groundwater attainment sampling results and the off-site supply well (with no exceedances of the applicable PADEP UARSHS MSCs), groundwater attainment was demonstrated.