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groundwater levels have fluctuated over a range of approximately four feet around an <br /> average elevation of about 7 ft below mean sea level(MSL). During earlier drilling <br /> activities in 1997,the groundwater level was reported to be approximately-16 ft MSL. <br /> Earlier data are not available for the site but regionally, San Joaquin County Flood Control <br /> District reports that in 1987, water levels in this area were as low as 35-40 feet below ground <br /> surface("bgs"; -30 to -35 ft MSL). This analysis of site conditions, leads to two <br /> Lobservations that are important in designing a workable remediation strategy for this site. <br /> 1. An implication of variable groundwater levels is that contamination has likely been.- <br /> smeared across the zone of fluctuation, including into the backfill material from the tank <br /> excavation(see Figure 1). As a result of smearing, the zone of residual contamination <br /> probably extends vertically from approximately 10 to 20 feet bgs. <br /> 2. Some contamination originally in the vadose zone(including LNAPL) is now <br /> submerged below the water table due to rising groundwater levels since the time of the <br /> original release. <br /> i <br /> F � <br /> I � <br /> s <br /> f � <br /> C <br /> f <br /> 2 <br /> i <br />