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. 28 July 2004 <br /> AGE-NC Project No 99-0657 <br /> Page 6 of 7 <br /> 3 4 GROUND WATER SAMPLING PROCEDURES <br /> Ground water sample collection will be performed in accordance with RWQCB guidelines (Tri- <br /> Regional Water Quality Control Board Recommendations for Preliminary Investigations and <br /> Evaluation of Underground Storage Tanks) sampling protocols <br /> 3 4 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 /> 3 4 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 dry prior <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 /> 3 4 3 Sample Withdrawal <br /> Water samples will be collected from the monitoring well using a disposable polyethylene bailer or <br /> 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 GeoEnvi ron mental,Inc <br />