Since 1998 Enpro has managed an ongoing turnkey remediation of a large, complex industrial site with multiple contaminants - primarily acetone and gasoline, benzene, toluene, ethylbenzene and xylenes - and challenging geology. We have performed p roject management and engineering and guided the regulatory strategy over the project lifecycle - investigation; fate & transport modeling, feasibility/treatability studies and engineering; risk assessment and remedial action plan; remediation system design, air and water discharge permitting, operation & maintenance (O&M), decommissioning; monitoring and ultimate closure. We have implemented remediation technologies including soil excavation (200 yards) and offsite disposal; soil vapor extraction (SVE) treatment by catalytic/thermal oxidation, ground water extraction (2 million gallons) and treatment by air stripping and carbon adsorption, dual-phase extraction and natural attenuation/monitoring. Remediation systems removed over 37,000 pounds of acetone and petroleum from ground water and soil.

When pump and treat systems reached the limit of technical effectiveness we negotiated remediation system shutdown and reduced monitoring with the lead agency. This saved the client an estimated $75,000 annually in O&M and monitoring costs. We measured inorganic parameters such as dissolved oxygen, ORP, pH and evaluated the site-specific capacity for natural attenuation. We demonstrated plume stability through an analysis of plume movement and spreading. We abandoned nine wells no longer needed, performed a well survey, prepared a case closure summary and demonstrated that the site met Low-Risk criteria established by the Regional Water Quality Control Board. We then performed a focused investigation and removed "hot spot" soils and ground water as part of the corrective action at this industrial site. We performed a remedial excavation and removed approximately 200 yards of soils containing acetone and gasoline. The soils were disposed offsite at a permitted treatment, storage and disposal facility (TSDF). We also pumped out approximately 15,000 gallons of ground water from the excavation, until risk-based industrial cleanup goals for the site were achieved. We decommissioned the pump & treat/SVE remediation system.

We performed extensive vertical and lateral delineation of residual contamination to residential environmental screening levels (ESLs) using direct push techniques. We prepared a Feasibility Study of in-situ remedial options including ORC, ozone injection and prepared life cycle cost estimates. A risk assessment and remedial action plan for further remediation are in preparation.