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29 September 2003 <br /> AGE-NC Project No. 01-0865 <br /> Page 9 of 10 <br /> 5.7. GROUND WATER MONITORING PROCEDURES. <br /> Groundwater sample collection will be performed in accordance with EHD guidelines(San Joaquin <br /> County Public Health Services Environmental Health Division Well Standards) and CVRWQCB <br /> guidelines (Tri-Regional Water Quality Control Board Recommendations for Preliminary <br /> Investigations and Evaluation of Underground Storage Tanks). <br /> 5.7.1. Static Water Level Measurements <br /> Before sampling and during groundwater monitoring, static water level will be measured using an <br /> electric water level indicator. Water level data will be recorded to the nearest 0.01-foot from a <br /> reference point marked of the top of the PVC well casing. Before and after each use, the <br /> measurement device will be rinsed with water. <br /> 5.7.2. Well Evacuation <br /> Subsequent to measurement of depth to water and prior to sampling,the well will be purged using <br /> an inertia pump or a disposable bailer to ensure that the sample is representative of the formation, <br /> rather than water standing in the well casing. The well will be purged until: 1) a minimum of three <br /> casing-water volumes has been removed from the well; and/or 2)the field-measured ground water <br /> parameters,pH,temperature and conductivity have stabilized.However,if a well is purged dryprior <br /> to evacuating three casing volumes, a ground water sample will be collected following 80 percent <br /> recovery of ground water within the well or after a minimum of 1 hour but within 8 hours of well <br /> evacuation. <br /> 5.7.3. Sample Withdrawal <br /> Water samples will be collected from the monitoring well using a disposable polyethylene bailer or <br /> a dedicated teflon tubing used in conjunction with the inertia pump.The bailers are disposed of after <br /> one use and require no decontaminating and the teflon tubing used with the inertia pump is either <br /> dedicated to each well or changed at each sampling event,thereby minimizing cross contamination <br /> due to sampling devices. Samples will be drawn and collected in such a manner that agitation and <br /> exposure of the groundwater to the atmosphere is minimal <br /> Advanced GmEnvironmental,Inc <br />