Laserfiche WebLink
7 <br />' 16 May 2002 <br /> S AGE-NC Project No 98-0426 <br />' Page 2 of 5 <br /> compounds and MTBE were detected in the grab ground water samples from two of the three <br />' borings <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 ValleyDivision 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 /> 1 Environmental Health Department (EHD) by letter dated 03 August 1999 <br /> 1 3 1 WELL MONITORING AND EVACUATION <br /> f <br /> On 12 February 2002, a Sohnst water level meter was used to measure the depth to ground water in <br /> 1 the five wells (MW1 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 /> 1 After the depth-to-ground water measurements were collected,the monitoring wells were purged of <br /> standing water using a new polyvinyl chloride (PVC) bailer Approximately 6 gallons of water, a <br /> 1 minimum of 3 casing-water volumes, were removed from the monitoring wells Ground water <br /> temperature,pH and conductivity were measured at approximately 1-gallon intervals during purging <br /> using an Oakton water analyzer Field sheets and data are included in Appendix A Purged water was <br /> 1 stored on site in labeled, 55-gallon DOT-approved drums <br /> • <br /> 1 Advanced Geo Environmental,Inc <br /> 1 <br />