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IBank of Stockton - Cutter Lumber Site Page 3 Summer Quarter Groundwater Monitoring Report ' Pro)ect No 102 2 . September 30, 1998 ' 2.0 GROUNDWATER MONITORING The following sections describe the procedures associated with the completion of ' groundwater monitoring at the site along with documenting the disposal of the well purge water associated with groundwater monitoring activity ' 2,1 Groundwater Sample Collection On September 15, 1998 Del-Tech Geotechnical Services of Oakdale, CA mobilized to the site to complete groundwater monitoring The groundwater monitoring procedure was as follows Upon arrival, each well was opened and the water level allowed to equilibrate As each well was opened, and prior to ' taking the depth to groundwater measurement, a PID organic vapor meter was used to screen for VOC's in the head space of the well The depth to I groundwater was then measured by lowering an electronically actuated all / water interface detector suspended from a polyethylene measuring tape calibrated to the nearest 0 01 foot (see groundwater monitoring data sheets in ' Appendix C) A careful notation made of the depth to groundwater as measured by the device Special effort was made to determine if measurable free phase . gasoline was present in MW-6 or MW-'l An electronically actuated oil / water ' interface detector was lowered into these wells for this purpose No measurable free product was observed In these two wells Each well was pumped by using a Grundfus submersible pump into the well and lowering it to bottom Well water was containerized in 55 gallon DOT approved polyethylene drums, properly labeled, and temporarily stored on-site The rate of well purging was monitored, and each well was purged of at least three casing volumes or until the groundwater parameters (temperature, conductivity, and ' pH) had stabilized indicating that water representative of actual aquifer conditions was entering the well Groundwater parameter stabilization was characterized by three successive readings within 10 percent After the wells had been allowed to recharge to at least 80 percent of their original volume, samples were collected from them using methods described below ' A stainless steel bailer belayed on a clean stainless steel line was used to collect each sample Bailer cleanliness was verified by collecting a bailer blank ' (pouring distilled water through the bailer and collecting it in a VOA vial) piior to collecting the analytical sample Before and In between uses, all sampling equipment was washed using a portable steam cleaner Disposable gloves weie worn by the sampling technician while collecting all samples The gloves weie . changed between the collection of each sample to reduce the potential for cross- contamination 2937 Veneman Ave ,#B240 Geo-Phase Environmental Inc Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0293 I