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1 During purging a minimum of three(3)weltvolumes, measured as the annular space of the well casing below the groundwater surface,'are removed from each well. However, in the case of very slow recharging wells, purging is deemed sufficient if the well contents are completely evacuated during purge operations. Unless recharge takes more thanes o hours, wells are sampled once the well is recharged to within in 80 percent of the pre-purge groundwater elevation. For very 'slow recharging wells.(wells pumped dry during purging), samples may be collected after two hours of recharge. Groundwater Sample Acquisition and :Handling Following purging operations, groundwater samples are collected from each of the wells, using pre-cleaned, single'-sample polypropylene, disposable bailers. The groundwater sample is discharged from the bailer to the sample container through a bottom emptying flow control valve to minimize volatilization. Collected water samples are discharged directly-into laboratory provided, pre-cleaned, 40- milliliter (ml) glass vials and sealed with Teflon-lined septum, screw-on lids. Labels documenting sample number, well identification, collection date and time, type of sample and type of preservative'(if applicable)are affixed to each sample. The samples are then placed into an ice-filled cooler,for delivery under chain-of-custody to a laboratory certified to perform the specified tests by;the State of California Department of Health Services Environmental Laboratory Accreditation Program. t � Trip Blanks I To help assure the quality of the collected samples and to evaluate the potent tal for cross contamination during transport to the laboratory,,a distilled-water trip blank accompanies-the samples in the cooler. The trip blank is typically analyzed for the presence of VOCs of concern. I� For petroleum hydrocarbons, the trip blank is typically analyzed for TPHg, BTEX, and MtBE by EPA Method 82606. Containment and Disposal of Generated Water/L.PH i p f All wastewater, purge water and LPH (if present)-generated during the field activities are retained on-site in appropriate containers (i.e. DOT-approved drums or bulk tanks) for future. disposal. Wastewater is delivered under appropriate manifest to a facility certified and licensed f to receive such waste streams. T