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Bank of Stockton - Cutter Lumber Site Page 3 Quarterly Groundwater Monitoring Report Project No. 102.2 • July 20, 2005 I ' 2.0 GROUNDWATER MONITORING The following sub-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 June 14, 2005, 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 groundwater was then measured by lowering an electronically actuated air 1 water interface detector suspended from a polyethylene measuring tape calibrated to the nearest 0.01 foot (see groundwater monitoring data sheets in Appendix B). A ' careful notation made of the depth to groundwater as measured by the device. No measurable free product was observed in the wells. At the time of the monitoring event, it was found that MW-10 was not accessible due to the fact of it havingbeen paved over. At the time of the next sampling P P g event, suitable equipment will be available to locate the well and remove the pavement that covers it. Each well was pumped with a Wattera pump and dedicated vinyl tubing lowered 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. After purging was completed, the Wattera pump was used to produce a water sample directly into the sample containers. Before and in between uses, all ' sampling equipment was washed using a portable steam cleaner. Disposable gloves were worn by the sampling technician while collecting all samples. The tgloves were 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