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Former Manna Pro Site Page 3 Quarterly Groundwater Monitoring Report Project No. 207.2 April 23, 2002 2.0 GROUNDWATER MONITORING The following sections describe the procedures associated with the completion of groundwater monitoring and ancillary activities at the site. 2.1 Groundwater Sample Collection On March 23, 2001, 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 wells which were to be sampled. 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 was made of the depth to groundwater as measured by the device. No measurable free product was observed in the wells. Each well to be sampled was pumped with a dedicated Waterra pump or by inserting a submersible Grundfos pump into the well and lowering it to bottom. Well water was containerized in 55-gallon, DOT approved r,. 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 ti.. 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 • w.. potential for cross-contamination. *" 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone (209) 569-0293 Modesto, CA 95356 Fax(209) 569-0293 t.r