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10 Quarterly Report - May 1998 <br /> t FORMER CHASE CHEVROLET(MADISON) FACILITY <br /> 423 North Madison Street, Stockton, California <br /> ' 1.0. INTRODUCTION <br /> In accordance with a request from Mr Jeffery Setness of Hartmann & Setness, Advanced <br /> GeoEnvironmental, Inc (AGE) has prepared this Quarterly Report summarizing field activities <br /> performed during the second quarter of 1998 at 423 North Madison Street, Stockton,California The <br /> ' scope of work included monitoring concentrations of dissolved petroleum hydrocarbons in ground <br /> water on the site and preparation of this report The location of the site is illustrated in Figure 1 - L <br /> Location Map Structures and monitoring well locations are illustrated in Figure 2 -Site Plan <br /> 1 Field activities were performed in accordance with guidelines for investigation of underground <br /> P g g g <br /> storage tank(UST) sites established by the Regional Water Quality Control Board- Central Valley <br /> Region (RWQCB-CVR) and by the San Joaquin County Public Health Services - Environmental <br /> Health Division(PHS-EHD) Background information was summarized in the Revised Corrective <br /> ' Action Plan -February 1997 and Site Investigation Report- UST No 8 prepared by AGE <br /> 2.0. PROCEDURES ' <br /> I <br /> 21 MONITORING WELL PURGE PROCEDURES <br /> ' On 07 May 1998,a Solinst water level meter was used to measure the depth to groundwater in eight <br /> monitoring wells relative to the tops of the well casings Monitoring well MW-18 was not accessible <br /> ' and therefore the depth to water was not measured The relative ground water elevations and <br /> hydraulic gradient were determined from these data (Table 1) <br /> Following measurement of ground water depths,in accordance with the revised monitoring schedule <br /> established at a 03 April 1998 meeting with the PHS-EHD,wells MW-1,MW-2,MW-4 and MW-13 <br /> were purged using a two-stage purge pump The purge pump was decontaminated prior to purging <br /> each well by pumping an Alconox solution followed by pumping tap water At least three well- <br /> volumes of water, approximately ten to fifteen gallons, were removed from each purged well <br /> Temperature,pH and conductivity of purged water were measured at regular purge volume intervals <br /> using an TCM model 52200 water analyzer The recorded stabilization data and field logs are <br /> included in Appendix A All purged water was stored in 55-gallon DOT-approved drums on-site <br /> 2 2 ^ COLLECTION OF GROUND WATER SAMPLES <br /> ' Water samples,were collected from each purged well using new disposable bailers Samples were <br /> • transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml of 18% hydrochloric acid as a <br /> Adv"ced GeoEnvironmentai,Inc <br /> 1 <br />