LONG-TERM SHORELINE OIL RELEASE CONTAINMENT CASE HISTORY

Heavy liquid-phase petroleum hydrocarbon (LPH) was observed along the west bank of the Schuylkill River adjacent to an active manufacturing plant near Philadelphia, Pennsylvania. While never confirmed, the source of the LPH was attributed to original and replacement #6 fuel oil underground storage tanks (USTs), which fueled steam boilers for the facility.The site's natural and anthropogenic features presented unique challenges to site characterization, oil recovery, and ultimately containment. An apparent trough in the bedrock underlying the site, believed to be a relic filled/buried stream that discharged to the Schuylkill River, continues to variably discharge to the River. The relic streambed orientation controls LPH migration from the former UST source area counter (northeast) to the aerial ground-water flow (southeast). Intercepting and containing the LPH therefore included focusing on the area of the River upstream of the source.Project objectives included elimination of direct oil discharge to the River and residual oil immobilization. An integrated dual-phase approach was developed and implemented. The first phase was design and installation of a containment system to physically halt direct oil discharge to the River. The second phase was design and installation of a pumping/recovery system that would prevent ground-water mounding behind the physical containment and recover residual oil to the point that it is no longer mobile (i.e. reduced to irreducible saturation).Operational data over a two-year period have validated the design concept and have reaffirmed the preferential transport of the oil in the streambed discharging to the Schuylkill River. The system gauging data in combination with the river gauging data have been incorporated into the operational data to confirm the hydraulic containment along the shoreline.