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G60(ogicafTecfinia Inc. Page 2 Groundwater Monitoring Report Project No. 750.2 ...� May 11, 2000 y,,, Spencer Surveying on April 19, 2000 surveyed the top of casing elevation of the new wells into the City of Escalon Benchmark No. 2. A signed map is included in Appendix D. 4.0 The average groundwater elevation in April was about 56.6 feet above MSL, which is approximately 61.5 feet below ground surface. �— A groundwater gradient was calculated for the April 18, 2000 groundwater monitoring event. It was flowing N80°W at 0.0025 ft/ft. Data is summarized in Table 1, Appendix A. Gradient directions are shown on Figure 3: Gradient Map. 1.2 Groundwater Sampling Procedure On April 18, 2000 Don Light of Del-Tech mobilized to the site to develop the monitoring wells and conduct a groundwater monitoring event. The wells were installed April, June and July of 1999 but were finished off below grade so that road and sidewalk consturction could take place. In early April of 2000 the wells were relocated and finished to ground surface. Before development was attempted, the wells were sounded for depth to water. Since the wells had never been developed after installation, Don Light first developed the wells by surging and pumping them until a clear stream of water was obtained. Once all of the wells had been developed, Mr. Light returned to the first well that had been developed and began the following sampling process: • The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra pump. Purging continued until the temperature, conductivity, and pH of the groundwater stabilized (<10% variation between three readings) indicating that formation water representative of aquifer conditions was entering the well. These water quality +.w parameters were measured at intervals of each well volume purged. • A stainless steel bailer was used to collect each sample. Care was taken to minimize sample agitation from the initial filling of the bailer to the transfer of the sample to the '-' VOA vials. • Once the sample containers were filled and capped, the bottles were inverted, tapped, and checked for headspace bubbles. Each sample container was identified and labeled with a unique designation, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory. • All non-disposable sampling equipment was decontaminated using a steam cleaner before and between uses. Disposable gloves were used by the technician to collect all samples and were changed with each sampling event. A field blank (prepared from water provided by the laboratory poured into a VOA vial on site) accompanied the samples to the laboratory to serve as checks against cross contamination. 4