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APPENDIX A Monitoring and Sampling Procedures BOULEVARD AUTOMOTIVE SERVICE 2151 Country Club Boulevard, Stockton, California STATIC WATER LEVEL MEASUREMENTS Before sampling and during groundwater monitoring, static water level are measured from wells MW-1 through MW-5 and MW-7 through MW-24 using an electric water level indicator. Water level data is recorded to the nearest 0.01-foot from a reference point marked of the top of the PVC well casing. WELL EVACUATION 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 utilizing disposable polyethylene bailers, a disposable 3/6-inch plastic tubing with an inertial pump or a dedicated %-inch plastic tubing with a Waterra inertial pump. Wells are purged until: 1) a minimum of three casing-water volumes is removed from the well; and/or 2) 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 water within the well, or after a minimum of 1 hour, but within 8 hours, of well evacuation. SAMPLE WITHDRAWAL Water samples are collected from each monitoring well using a disposable polyethylene bailer or a dedicated plastic/Teflon tubing in conjunction with the inertia pump. Bailers are disposed 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 groundwater to the atmosphere is minimal. Ground water sample containers were labeled with the well designation, date, time, and sampler's initials. SAMPLING HANDLING Groundwater samples are collected into laboratory-supplied 40-ml volatile organic analysis (VOA) vials with no preservative and, into one-liter amber glass containers without a Advanced GeoEnvironmental,Inc.