ARCHIVED REPORTS_XR0008721 - Laserfiche WebLink

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' 19 November 2004 AGE-NC Project No 99-0559 ' Page 2 of 7 2.0• PROCEDURES Ground water monitoring and sampling were performed on 16 September 2004 The work was ' performed in accordance with guidelines established by the California Regional Water Quality Control Board (CRWQCB) - Central Valley Division for subsurface investigation of underground storage tank (UST) sites, and with the San Joaquin County Environmental Health Department ' (EHD)-approved Preliminary Site Assessment Work Plan, dated 12 October 1999, and Interim Remediation and Site Assessment Work Plan, date 25 January 2001, both prepared by AGE ' 2 1 WELL MONITORING AND EVACUATION Depth to ground water was measured in well chambers A through E of the multi-level wells MW-5 through MW-7 from the top of the well casings to the nearest 0 01-foot,utilizing a Slope water level meter,ground water elevations and gradients in this report are based on the measured depths Ground ' water was not observed or measurable in single-level wells MW-1 through MW-3, although free product was encountered, these wells were considered dry 10 After ground water depth measurements, well chambers B through E of the multi-level monitoring wells MW-5 through MW-7 were purged by lowering and raising a 3/8-inch outer diameter, length- discrete polyethylene hose equipped with a ball-valve water tip through the top chambers into the specific water-charged screened section, well chamber A was not purged or sampled due to lack of water in the chamber Approximately 125 to 4 gallons of ground water(a minimum of three casing- water volumes per well),when available,were removed from the multi-level monitoring well levels B, C, D and E Temperature, pH and conductivity were measured for stabilization at regular purge- volume intervals during monitoring using an Oakton water analyzer, field data and logs are included ' in Appendix A Purged ground water was containerized in 55-gallon drums and processed on-site for discharge under permit ' Dedicated, disposable polyethylene bailers were utilized to purge standing free product and water from wells MW-I through MW-3 ' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES Prior to ground water sampling,the ground water level in each well was measured to ensure that the well achieved a minimum of 80 percent recharge Following depth measurement, ground water samples were collected from well chambers B through E of multi-level wells MW-5 through MW-7 utilizing 3/8-inch diameter polyethylene tubing The ground water samples were transferred into three 40-nil EPA-approved volatile organic analysis (VOA) vials containing 0 5 ml 18% Advanced GeoEnvironmental,Inc