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Bank of Stockton • Cutter Lumber Site Winter Quarter Groundwater Project No. 102,2 Monitoring Deport +..� 20 April 1999 Page 3 �. 2.0 GROUNDWATER MONITORING The following sections describe the procedures associated L„ groundwater monitoring at the site along with documenting the e completion e well purge water associated with groundwater monitoringactivity.disposal of the LN 2.1 Groundwater Sample Collection On 24 March 1999, Del-Tech Geotechnical Services of Oakdale, CA mobilize the site to complete groundwater monitorinound to torin Procedure was as follows: Upon arrival, each well hwas�ope ed andwatermonthe'wateg 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 / 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, although MW-7 was observed to have a sheen.. w Each well was pumped by inserting 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) prior to collecting the analytical sample. 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 gloves were changed between the collection of each sample to reduce the potential for cross- contamination. Lo 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone (209)569-0293 Modesto, CA 95356 Fax (209) 569-0293 LM