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SECOR INTERNATIONAL INCORPORATED STANDARD PROCEDURE FOR GROUNDWATER SAMPLING Depth to Groundwater/LPH Thickness Measurements Prior to purging each of the wells, the depth to groundwater and thickness of SPH, if present, within each well casing Is measured to the nearest 0 01 foot using either an electronic Solinst water level Indicator or an electronic oil-water Interface probe Measurements are taken from a point of known elevation on the top of each well casing as determined In accordance with previous surveys Groundwater Monitoring Well Purging Groundwater wells that do not contain LPH are purged using a dedicated 1-inch diameter polyvinyl chloride (PVC) "stinger," bailer, or groundwater pump Purge water is contained on-site In 55-gallon DOT-approved drums To help assure that the collected samples are representative of fresh formation water, the conductivity, temperature, and pH of the delivered effluent are monitored and recorded using a Cambridge Hydac meter, or another meter similar in nature during purge operations Purge operations are determined to be sufficient once successive measurements of pH, conductivity, and temperature stabilize to within fl- 10 percent During purging, a minimum of three (3) well volumes, 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 than two hours, wells are sampled once the well Is recharged to within 80 percent of pre-purge groundwater elevations For very slow recharging wells (wells pumped dry during purging), samples may be collected after two hours of recharge Groundwater Sample Acquisition, Handling, and Analysis Following well development, 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, hydrochloric acid-preserved 40 milliliter (ml) glass vials and sealed with Teflon-lined septum, and screw-on lids for analysis of TPHg, BTEX, fuel oxygenates (MtBE, TAME, DIPE, EtBE, TBA), 1,2-DCA, and EDB by EPA Method 8260B 11ConocoPhdlips\Retail Sites1111931Reports111193 Off-Site Well Install 1-05 doe