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26 September 2003 <br /> • AGE-NC Project No. 02-0896 <br /> Page 8 of 9 <br /> 4.4. GROUND WATER SAMPLING PROCEDURES <br /> Ground water sample collection will be performed in accordance with CRWQCB guidelines (Tri- <br /> Regional Water Quality Control Board Recommendations for Preliminary Investigations and <br /> Evaluation of Underground Storage Tanks) sampling protocols. <br /> 4.4.1. 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 /> 4.4.2. 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 /> 4.4.3. 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 /> 4.4.4. Sample Handling <br /> Ground water samples will be collected into laboratory-supplied 40-m1 VOA vials containing 0.5 <br /> ml of hydrochloric acid as preservative, one-liter amber glass containers without a sample <br /> Advanced GeoE nviro n mental,Inc. <br />