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Dual Pump (LNAPL & Groundwater Recovery), Multi-Well Groundwater Pump and Treat, Large Scale Soi

Project Name: Former Service Station

Location: Upstate, NY

Impact Characterization: Mixed fuels, primarily gasoline/kerosene, resulting from activities associated with the operation of a former retail gasoline storage/sales facility. Petroleum impacts to both the subsurface soil and groundwater regimes. Contamination was documented beneath the site proper as well as at several adjacent properties due to prolonged groundwater transport.

Technical Overview: This project resulted from one or more historic releases associated with former retail fuel storage/dispensing activities at the subject site. PES’s initial response involved a complete assessment of subsurface conditions to refine the comprehension of the initial definition of the contaminant plume. The assessment included the definition of contaminant type/spatial distribution, geologic/hydrogeologic subsurface parameters, aquifer analysis, and baseline transport characteristics (groundwater/contaminant dispersion profile). The initial assessment and subsequent testing established a substantial negative environmental impact that included the existence of light non-aqueous phase liquid (LNAPL)/free product contamination. Impacts in the subsurface involved both vadose and phreatic aquifer components starting at depths of twenty feet below grade. The documented adverse impact extended from the site proper to adjacent third-party parcels. PES developed a remedial feasibility plan presenting groundwater pump and treat technology to gain hydraulic control over the expanding plume and a combination of soil vapor extraction and air sparging to address the absorbed and dissolved phase impacts. The remedial feasibility plan was submitted to the NYS DEC and subsequently approved and implemented.

Pilot testing was performed to generate site-specific data to allow for a full-scale remedial system design. The resulting pump and treat remedial corrective action incorporated four six-inch diameter forty foot deep groundwater recovery wells with down-well separate dual pumping (free product and groundwater) capability at one location and a groundwater treatment system consisting of a coalescing plate oil/water separation, low profile air stripper, 1400-pounds of activated carbon polish all capable of treating the impacted groundwater to allowable discharge standards at a rate of 40 gallons per minute.

The resulting soil vapor extraction and air sparge remedial system incorporated nine nested sparge and ventilation wells, a 15-horsepower vapor extraction blower capable of inducing airflow of more than 3,000 feet per minute and a 15 horsepower sparge compressor.

Each of the remedial system wells were properly installed by Aquifer Drilling and Testing, Inc., (ADT) under the supervision of PES geologic staff, utilizing hollow-stem auger drilling and standard split spoon soil sampling methodologies. Each system was designed, constructed, installed (including the safety interlocks and remote monitoring telemetry), operated and maintained by PES. Both pump and treat and soil vapor extraction/air sparge systems are each housed in mobile trailers thereby eliminating cost associated with enclosure construction and/or demolition.

Site Progression Specifics: The site reached its primary remedial goals and the active remedial program was terminated by the local regulatory.

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