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Monitoring and Sampling Procedures <br /> RALPH SQUARE-BUI <br /> 2122 South Airport Way, Stockton, California <br /> STATIC WATER LEVEL MEASUREMENTS <br /> Before sampling and during groundwater monitoring, static water levels are measured <br /> using an electric water level indicator. Water level data is recorded to the nearest 0.01- <br /> foot from a reference point marked of the top of the PVC well casing. <br /> WELL PURGING <br /> Subsequent to measurement of depth to water and prior to sampling, each well is purged <br /> to ensure samples are representative of the formation, rather than standing water in the <br /> well casing. Wells are purged using a dedicated disposable polyethylene bailer. <br /> Wells are purged until a minimum of three casing-water volumes is removed from the well <br /> and/or the field-measured ground water parameters (pH, temperature, and conductivity) <br /> are stabilized. However, if a well is purged dry prior to evacuating three casing volumes, <br /> a sample is collected following 80 percent recovery of groundwater within the well or after <br /> a minimum of 1 hour, but within 8 hours, of well purging activities. <br /> SAMPLE WITHDRAWAL <br /> Water samples are collected from each monitoring point using a disposable polyethylene <br /> bailer. Bailers are disposed of after a single use (sample) and require no decontaminating; <br /> plastic tubing used with the inertia pump is either dedicated to each well point or changed <br /> at each sampling event, thereby minimizing cross contamination due to sampling devices. <br /> Samples are drawn and collected in such a manner that agitation and exposure of the <br /> groundwater to the atmosphere is minimal. <br /> SAMPLE HANDLING <br /> Groundwater samples are collected into laboratory-supplied 40-ml volatile organic <br /> analysis (VOA) vials with preservative and, if appropriate, one-liter amber glass <br /> containers without a preservative. Samples are collected with no visible air bubbles are <br /> present in the vials after filling and capping. Following collection, samples are <br /> appropriately labeled, placed on ice, and kept in a cooler until delivered to a State of <br /> California Environmental Laboratory Accreditation Program (ELAP)-certified analytical <br /> laboratory, for analysis. The samples are analyzed for: <br />