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i APPENDIX B Monitoring and Sampling Procedures McBillin Real Estate Investment 2154 South EI Dorado Street, Stockton , California STATIC WATER LEVEL MEASUREMENTS Before sampling and during round water monitoring , static water levels will be measured P 9 9 9 9 . at all wells using an electric water level indicator. Water level data is recorded to the nearest 0 .01 -foot from a reference point marked on the top of the PVC well casing . WELL PURGING Subsequent to measurement of depth to water and prior to sampling , each well is purged to ensure samples are representative of the formation , rather than standing water in the well casing . Wells are purged using a Waterra inertial pump and dedicated %-inch plastic tubing . Wells are purged until a minimum of three casing-water volumes are removed from the well and/or the field-measured ground water parameters (pH , temperature, and conductivity) are stabilized . However, if a well is purged dry prior to evacuating three casing volumes , a sample is collected following 80 percent recovery of ground waterwithin the well , or after a minimum of one hour, but within eight hours, of purging procedures . SAMPLE WITHDRAWAL 1 Water samples are collected from each monitoring well using either an interia pump with - dedicated plastic/Teflon tubing or a disposable polyethylene bailer. Bailers are disposed - � of after a single use (sample) and require no decontaminating ; plastic tubing used with the inertia pump is either dedicated to each well point or changed at each sampling event, thereby minimizing cross contamination due to sampling devices. Samples are drawn and collected in such a manner that agitation and exposure of the ground water to the atmosphere is minimal . SAMPLE HANDLING r Groundwater samples are collected into laboratory-supplied 40-ml volatile organic analysis (VOA) vials without preservative and , if appropriate, one-liter amber glass containers without a preservative; the samples are collected with no visible air bubbles present in the vials after filling and capping . Following collection , samples are appropriately labeled , placed on ice , and kept in a cooler until delivered to Cal Tech Environmental Laboratories Advanced GeoEnvironmental, Inc.