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July 15, 1997 to an arbitrary datum of 14 feet above sea level Groundwater elevation data are <br /> presented in Table 2 <br /> 27 Groundwater Sampling and Anal <br /> 1 On July 3, 1997, groundwater samples were collected from wells MW 1, MW2, MW3, and CW <br /> The samples were collected after purging a minimum of three well volumes and stabilization of <br /> electric conductivity, pH, and temperature Field development/purge logs are presented in <br /> Appendix IV <br /> Subsequent to purging, groundwater was sampled and transferred to appropriate sample <br /> containers, using clean, disposable bailers with bottom emptying devices to reduce volatilization <br /> Sample containers were then labeled with sa a identification, placed on ice, and shipped under <br /> chain-of-custody to GTEL <br /> ' The water samples were analyzed by GTEL for TPHg, BTEX, and MTBE by EPA methods 8015 <br /> modified and 8020 Groundwater analytical results are summarized in Table 2, and laboratory <br /> data sheets are presented in Appendix V <br /> 3.0 SUBSURFACE CONDITIONS <br /> Soils encountered beneath the site consist primarily of clay with varying amounts of silt and sand <br /> to a depth of approximately 45 feet below grade, the maximum depth explored An apparent silty <br /> sand lens was noted at a depth of approximately 11 5 to 15 feet below grade A lean clay layer <br /> was also observed at approximately 30 feet below the ground surface in borings SBI through <br /> SBS <br /> Groundwater beneath the site was first encountered at approximately 29 5 feet below grade <br /> After well completion, the piezometric surface stabilized to approximately 29 feet below grade <br /> 1 Based on July 3, 1997 monitoring data (Table 2), groundwater flows to the north-northeast at a <br /> gradient of approximately 0 005 ft/ft or 25 feet per mile A groundwater gradient map for July 3, <br /> ' 1997 is presented on Figure 3 <br /> 4.0 RESULTS <br /> 44.1 Soil Contamination <br /> Laboratory analytical results indicated TPHd was detected in the samples collected from boring <br /> ' SB3 (Table 1) at concentrations above laboratory detection limits TPHd was not detected in any <br /> samples collected from borings SB 1, S132, SB4, and SB7 Soil samples collected from borings <br /> SBS and SB6 were not analyzed for TPHd <br /> ' w\9773 I VcporU\psj doc 4 <br /> SM•TH <br />} 1 <br />