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1 ' PROJECT STATUS AND MONITORING REPORT USA PETROLEUM STATION#110 - STOCKTON ' JANUARY, 1996 2.0 GROUNDWATER MONITORING WELL SAMPLING METHODOLOGY ' 2.1 Groundwater Elevations ate ' Depths to groundwater measurements were collected on October 6, 1995, using an electronic water level indicator Prior to measuring groundwater depths the new and old wells were surveyed to establish their relative elevations The top of casing elevations were used as reference points, and all elevations were measured from the top of the casing Groundwater elevations recorded during this and previous events are presented in Table 1 ' 2.2 Monitoring Well Purging t Each monitoring well was purged by pumping at least three well volumes of water from each well (MW-1-P through MW-6-P) Temperature, pH and conductivity were monitored while the wells were being purged Field readings from MW-4-P detected what appeared to anomolus pH ' readings greater than 12 Field readings during well development were all below 9 Since this was the first sampling event for this well, the anomoulus reading may be due to well construction (i e cement or bentonite in the water) This issue will continue to be during future sampling events Data was recorded on field data sheets The wells were allowed to recharge to at least 80 percent of their initial static water levels prior to sampling Groundwater purged from the wells was placed into appropriately labeled DOT approved 55-gallon drums The purge water will be disposed of appropriately after the analytical results are reviewed Disposal of the purge water is the responsibility of the client A summary of the field data is presented in Table 2, and copies of the field data sheets are included in Appendix A 1 2.3 Groundwater Sampling ' Each groundwater sample was collected using a new Teflon disposable bailer The sampled water was placed into laboratory prepared, sterile, 40 milliliter glass, one liter plastic, and one quart amber containers The sample containers were filled to the top to eliminate aur space and were sealed with Teflon-lined caps Water sample containers were labeled with the name of the sampler, the date, the fob number,the preservative, and an identifying number The samples were - t then transported to Sierra Laboratories (Serra) in Laguna Hills, Califorrua, a state certified laboratory Full chain-of-custody (COC) protocol was followed during sample handling and delivery ' 2.4 Groundwater Analyses ' Analyses of the groundwater samples were performed by Sierra in accordance with state guidelines and EPA protocol The samples were analyzed for TPH G,TPH D, BTEX, and total lead using EPA Methods 8015M, 8020 and 7421, respectively 1 ' 2