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t <br /> 21 June 2002 <br /> AGE-NC Project No 98-0426 <br /> Page 2 of 5 " <br /> S <br /> compounds and MTBE were detected in the grab ground water samples from two of the three <br /> borings <br /> I t I <br /> Based on the soil probe and monitoring well boring results, the vertical extent of Impacted soil <br /> beneath the former USTs appears`to be defined Also,petroleum hydrocarbons were not detected in <br /> soil samples analyzed from borings B1, B2, B4, B5, B6, MW4 and MW5, thereby defining the <br /> " lateral extent of impacted soil <br /> Ground water monitoring has been performed at he site since October 1999 Ground water gradient <br /> determinations have Indicated a consistently northeast ground-water flow Hydrocarbon-Impacted <br /> ground water appears to be limited to the former UST and dispenser area <br /> Complete background information and details of previous investigations at the site were detailed in <br /> AGE's Preliminary Investigation and Evaluation Report-March 1999, dated 26 March 1999, and <br /> Additional Site Assessment and Monitoring Well Installation Report, dated 05 March 2002 <br /> . 3.0. PROCEDURES <br /> Field work was performed in accordance with guidelines established by the California Regional <br /> Water Quality Control Board-Central Valley Division for investigation of underground storage tank <br /> (UST)sites Ground water monitoring procedures were performed as outlined in the AGE-prepared <br /> Monitoring Well Installation Work Plan,dated 29 July 1999,as approved by the San Joaquin County <br /> u Environmental Health Department(EHD)by letter dated 03 August 1999 <br /> f <br /> LI n ( I y I <br /> 3 1 WELL MONITORING AND EVACUATION <br /> On 10 May 2002, a Solinst water level meter was used to measure the depth to ground water in <br /> monitoring wells MWI through MW5 relative to the tops of the well casings The relative ground <br /> water elevations and gradient were determined from these data (Table 1) <br /> f <br /> rAfter the depth-to-ground water measurements were collected,the monitoring wells were purged of <br /> standing water using new plastic bailers Approximately 6 gallons of water,a minimum of 3 casing- <br /> water volumes, were removed from the monitoring wells Ground water temperature, pH and <br /> conductivity were measured at approximately 1-gallon intervals during purging using an Oakton <br /> water analyzer Field data sheets are Included in Appendix A Purged water was stored on site in <br /> labeled, 55-gallon DOT-approved drums ` <br /> IAdvanced GeoEnvsronmentai,Inc <br />