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QUARTERLY REPORT <br /> e <br /> T September 1996 E <br /> ' Pacific Gas <br /> 2088 Mariposa Road, Stockton, California ` <br /> 10. INTRODUCTION <br /> I <br /> f <br /> rIn accordance with the request of Mr Manuel Sanchez,Advanced GeoEnvironmental, Inc (AGE) <br /> has performed quarterly ground water monitoring activities at 2088 Mariposa Road, Stockton, <br /> ' f California (the site) <br /> This report details the monitoring and sampling procedures performed on 09 September 1996 and <br /> presents the results of the laboratory analysis The objective of the sampling is i to monitor <br /> concentrations of petroleum hydrocai bons in ground water at the site A description of previous <br /> investigations at the site was included in the Quay lei Iy Report-Februai y 1996, dated 17;April 1996, <br /> prepared by AGE The location of the site and the immediately surrounding area are illustrated on <br /> Figure 1 -Locaiton Map Structures and monitoring well locations at the site are depicted on Figure <br /> 2 - Site Plan <br /> The morutonng and sampling was performed in accordance with San Joaquin County Public Health <br /> Services - Environmental Health Division (PHS-EHD) and Regional Water Quality Control Board <br /> (RWQCB) guidelines for the investigation of underground storage tank (UST) sites <br /> 2.0. PROCEDURES <br /> ' 2 1 MONITORING WELL PURGE PROCEDURES <br /> On 09 September 1996, the depth'to ground water in each monitoring well was measured to the <br /> nearest 0 01 foot utilizing a Solist water level meter Relative ground water elevations were calculated <br /> ' by subtracting the depth to ground water from the relative casing elevations surveyed from a <br /> temporary benchmark assigned an arbitrary elevation (Table 1-Relative Ground Water Elevations) <br /> ' Relative ground water elevations were plotted and contoured on a scaled site map, upon which a <br /> ground water gradient map was approximated (Figure 3-Relative Gi ound Water F levation Map) <br /> After ground water levels were measured, a minimum of three well volumes of ground water was <br /> purged from each well utilizing a disposable bailer Approximately 10 gallons of ground water were <br /> removed from wells MW-I through MW-3 11 <br /> Temperature, pH and conductivity were measured at regular intervals from each well using an ICM <br /> model 52200 water analyzer Stabilization data and field logs are enclosed as Appendix A Purged <br /> water was transferred into 55-gallon drums, which were subsequently stored on-site in an area <br /> inaccessible to the general public <br /> I <br /> r e E <br /> t <br /> 1 <br />