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1 <br /> } tt <br /> Quarterly Report - February 1998 <br /> • FORMER CHASE CHEVROLET (MADISON) FACILITY <br /> 423 North Madison Street, Stockton, California <br /> ' 10 INTRODUCTION <br /> In accordance with a request from Mr Jeffery Setness of Hartmann & Setness, Advanced <br /> GcoEnvironmental, Inc (AGE) has prepared this Quarterly Report summarizing field activities <br /> performed during the first 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 /> ,1 water on the site and preparation of this report The location of the site is illustrated in Figure 1 - <br /> Location Map Structures and monitoring well locations are illustrated in Figure 2 -Site Plan <br /> Field activities were performed in accordance with guidelines for investigation of underground <br /> storage tank (UST) sites established by the Regional Water Quality Control Beard - Central Valley <br /> ' Region (RWQCB-CVR)and the San Joaquin County Public Health Services- Environmental Health <br /> Division (PHS-EHD) Backgiound information was summarized in the Revised Col rechve Acta on <br /> Plan - Februai y 1997 and Site Investigation Report - UST No 8 prepared by AGE <br /> lie 20 PROCEDURES <br /> r <br /> 2 1 MONITORING WELL PURGE PROCEDURES <br /> t <br /> ' On 04 Febivary 1998, a Solinst water level meter was used to measure the depth to giound water in <br /> each well relative to the tops of the well casings The relative ground water elevations and hydiaulic <br /> gradient weie determined fiom these data (Table 1) <br /> y <br /> Following measuiement of groundwater depths each monitoring well was puiged using a two-stage <br /> purge pump The purge pump was decontaminated prioi to purging each well by pumping an <br /> Alconox solution followed by pumping tap water At least three well-volumes, apprommately ten <br /> to fourteen gallons of water, weie removed fiom each well, except MW-8, from which <br /> appioximately 50 gallons of water were remix ed Temperature pH and conductivity of purged water <br /> were measuied at regular inter\als during purging using an ICM mode1,52200 water analyzer The <br /> iecoided stabilization data and field logs aie included in Appendix A A11`purged water was stored <br /> ' in 55-gallon DOT-approved drums on-site <br /> 2 2 COLLECTION OF GROUND WATER SAMPLES <br /> ' Water samples were collected fiom each well using new disposable bailers Samples were transferred <br /> into 40-m1 EPA-approved VOA vials containing 0 5 nil of 18% hydrochloric acid as a preservative <br /> and into 1-liter amber bottles without preservative The samples weie transported in a chilled <br /> Adrrnnced CcoEnN ironmental,Inc <br />