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Monitoring and Sampling Procedures Former SAN JOAQUIN COGENERATION 17200 Murphy Parkway, Lathrop, San Joaquin County, California STATIC WATER LEVEL MEASUREMENTS Before sampling and during groundwater monitoring, static water levels will be measured 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 or a disposable polyethylene bailer. 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 water within the well, or after a minimum of one hour, but within eight hours, of purging procedures. SAMPLE WITHDRAWAL Water samples are collected from each monitoring well using either an inertia 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 groundwater to the atmosphere is minimal. SAMPLE HANDLING Groundwater samples are collected into laboratory-supplied sample containers for analysis of the appropriate constituent(s). Following collection, samples are appropriately labeled, placed on ice, and kept in a cooler until delivered to a California Environmental Laboratory Accreditation Program (ELAP)-certified laboratory, for analysis of one or more of the appropriate constituent(s) listed below.