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' 12 August 2002 <br /> . AGE-NC Project No 95-0103 <br /> ' Page 8of11 <br /> 3.0. QUARTERLY GROUND WATER MONITORING AND SAMPLING <br /> On 30 May 2002, ground water monitoring and sampling were performed on monitoring wells <br /> MW-2 through MW-6 Ground water monitoring activities were performed in accordance with <br /> guidelines established by the San Joaquin County Environmental Health Department (EHD) and <br /> California Regional Water Quality Control Board - Central Valley Region(CRWQCB) <br /> 3 1 WELL MONITORING AND EVACUATION <br /> ' A Solinst water level meter was used to measure the depth to ground water in monitoring wells <br /> MW-2 through MW-6 relative to the tops of the well casings(Table 2) The ground water elevation <br /> ' in each well was calculated by subtracting the measured depth to ground water from the surveyed <br /> casing elevation <br /> ' After water levels were measured,between 9 and 11 gallons of ground water(a minimum of three <br /> casing water-volumes per well)were evacuated(purged)from wells MW-2 through MW-6 utilizing <br /> polyethylene disposable bailers Temperature,pH and conductivity were measured for stabilization <br /> lieat regular purge-volume intervals from each well using an Oakton water analyzer <br /> t The monitoring equipment was washed in an Alconox solution and rinsed with tap water prior to <br /> purging Purged water was stored in 55-gallon drums on the site Field measurements of purged <br /> ground water are included in Appendix E <br /> 1 <br /> 3 2 GROUND WATER SAMPLE COLLECTION AND ANALYSIS <br /> 1 Water samples were retrieved from each purged well using the disposable bailers after allowing the <br /> well to achieve a minimum of 80 percent recharge prior to sample collection The samples were <br /> ' transferred into 40-m1 EPA-approved volatile organic analysis(VOA)vials containing 0 5 ml of 18% <br /> hydrochloric acid as a sample preservative The samples were properly labeled and transported in <br /> a chilled container under chain-of-custody to Cal Tech Environmental Laboratories, Inc (CTEL), <br /> ' a DHS-certified laboratory, for analysis The ground water samples were analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br /> ' Method 8015-Modified, <br /> • Benzene, toluene, ethyl-benzene and total xylenes (BTEX) with methyl-tert-butyl ether <br /> ' (MTBE) in accordance with EPA Method 8021, and <br /> Advanced GeoEnvironmental,Inc <br />