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r <br /> E&R Freeman - 2 - 13 February 2013 <br /> 3138 E. Main St., Stockton <br /> San Joaquin County <br /> The Workplan proposed: <br /> • installation of a security fence around the property for protection of RDM employees and <br /> future Site remediation equipment; <br /> • demolition of the derelict gas station building/lawnmower shop, which now covers the fuel <br /> dispenser island, in order to facilitate an additional soil and groundwater investigation and <br /> a remedial pilot study; <br /> • installation of one onsite cone penetrometer testing (CPT-1) boring to 100' below ground <br /> surface (bgs) and retrieval of one grab water sample for analyses, to determine the <br /> vertical extent of the groundwater plume; <br /> • installation of two nested soil vapor extraction wells (SVE-1A/B and SVE-2A/B), each <br /> screened 10'-25' bgs and 35'-50'bgs, and one air sparge well (AS-1), screened 63'-65' <br /> • bgs by hollow stem auger in the most impacted soil near the former dispenser island. <br /> RDM will conduct a 24-hour (12 hours for each nested SVE well) SVE pilot study and a <br /> 96-hour AS pilot study, using MW-1 through MW-3 as observation wells. A separate <br /> SVE/AS pilot study report will be submitted; and <br /> • • installation of five offsite monitoring wells (MW-4 through MW-8), screened 45' bgs to 65' <br /> bgs, to determine the lateral extent of the groundwater plume that now encompasses the <br /> entire Site monitoring well network. Initially, four (4) quarters of groundwater monitoring <br /> will be conducted for MW-1 through MW-8. A soil and groundwater investigation report <br /> will be submitted. <br /> • Eight (8) soil samples will be collected from each boring (monitoring and remediation wells) by <br /> advancing a split-spoon sampler at 5' intervals and also where soil cuttings show lithology <br /> changes. A photoionization detector (PID) will screen the soil samples for organic vapors. Total <br /> depths of borings and the well screen intervals may be adjusted in the field, depending on site- <br /> specific conditions observed during drilling. <br /> • <br /> Soil and groundwater analyses by USEPA Method 8260B include TPHg, BTEX, the five fuel <br /> oxygenates including MTBE, TBA, tert amyl methyl ether (TAME), di-isopropyl ether (DIPE) and <br /> ethyl tert butyl ether (ETBE), lead scavengers 1,2-DCA and ethylene dibromide (EDB), <br /> naphthalene, and a full scan of chlorinated solvents (VOCs). TPHd will be analyzed by USEPA <br /> • Method 8105M, with the addition of a silica gel cleanup (SGC) if TPHd is detected without SGC. <br /> Six (6) soil samples from select depths will be analyzed for geotechnical parameters for future <br /> fate and transport modeling. Monitored natural attenuation parameters will be analyzed for <br /> select groundwater wells (upgradient, source area, and downgradient) for future closure <br /> consideration. <br /> • <br /> RDM will acquire access agreements/easements for four of the five offsite borings/wells (MW-8 <br /> will be located on the adjacent, currently unoccupied residential section of the property owned <br /> by HHLLC) and permits from City of Stockton and the San Joaquin County Environmental <br /> • <br />