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1 1 in conjunction with a groundwater removal and treatment system The purpose of the groundwater JP removal system is to reduce the migration of dissolved hydrocarbons in groundwater and lower groundwater elevations in order to expose hydrocarbon impacted soil to vapor extraction The shallow water-bearing zone experienced high recharge characteristics and a groundwater extraction radius of influence in excess of 100 feet Soil vapor extraction testing at the Site indicated an effective radius of influence of approximately 33 feet The results of feasibility testing at the Site indicate that soil vapor extraction and groundwater pump and treat technology are suitable for the removal of VOCs from the Site 6 2 3 OPTION III - Groundwater PumR and Treat Extraction wells are a proven removal and recovery technology used for hydrodynamic control of groundwater, capture of impacted groundwater, or the altering of the direction of groundwater flow Well systems are versatile and can be used to contain, remove, divert or minimize development of a ' plume under a variety of site conditions A remedial system utilizing pump and treat would involve the utilization of extraction wells at a spacing determined during pilot testing activities An electric or pneumatic submersible pump would be installed at the base of the well and manmfolded to a central recovery tank Groundwater would be treated using carbon or other method and discharged into the sanitary sewer or storm drain under permit The shallow water-bearing zone experienced high recharge characteristics and a radius of influence in excess of 100 feet indicating that this technology ' is adequate to remove VOCs from the Site 6 2 4 OPTION IV - Well Inoculation and Low Flow Air Infection Park has identified an enzyme product (HCZyme) which has the capacity to break down petroleum hydrocarbons (including MTBE) which makes them more amenable to biodegradation In order to ' provide sufficient dissolved oxygen for the microbes in groundwater, low-flow air infection is typically conducted Air injection into the subsurface groundwater formation is difficult due to tight submerged soils with significant water table fluctuations (15 feet over 3 years) Even distribution of enzymes and oxygen through the complex fori-nations beneath the Site would be difficult Due to the above-mentioned drawbacks, enzyme addition and low flow air infection was not selected as the ' remedial option of choice for the Site 7.4 REMEDIAL SYSTEM DESIGN Following a review of existing Site geologic and hydrogeologic characteristics, the well testing ' results, the magnitude and extent of hydrocarbon-affected soil and groundwater, and the analysis of remedial action alternatives, Park recommends that soil vapor extraction and groundwater pump and treat be retained as the remedial option of choice for the Site Pilot test results have proven that the groundwater pump and treat and soil vapor extraction technologies are capable of remediating the contaminated soil and groundwater at the Site Underground vapor extraction piping has already been installed by Thrifty Groundwater extraction will alter subsurface groundwater flow directions A.11528Ji ASA 17