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. i <br /> Shadow Lake Mobile Home Community RMC Geoscience, Inc. <br /> April l6, 2010 <br /> Page 2 <br /> 1 through 18(the pits are numbered from north to south)include a 6-inch-diameter perforated� p PVC � <br /> Pipe positioned in the center of the pit, with the remainder of each pit backfilled with gravel. <br /> Seepage pit numbers 19 through 24 are relatively newer than pits I through 18 and inc <br /> inch-diameter perforated PVC pipe in the center of the pit. lude an 8- <br /> GEOLOGIC CONDITIONS <br /> The Shadow Lake facility is located ithe Central Valley and is protecte <br /> levees along the Calaveras River(the levees are maintained by the San J afrom a 100 year flood by f <br /> District). The geology of the area is characterized by alluvial deposits from thee Sierquin Area ra Nevada Control <br /> and <br /> Coastal mountain ranges that border the Central Valley. Soil borings advanced as part ofmonitoring <br /> well installation at the site indicated similar lithology at each ofthe soil boring locations. In general, <br /> the subsurface soils encountered between 10 and 70 feet below the ground surface are relatively <br /> uniform and consist of light brown to brown fine-grained silty sand and sandy silt. Silty sand appear <br /> to be the predominant soil type based on the samples recovered from the borings. Bedding was not <br /> observed in any ofthe samples that were recovered and individual soil type horizons(silty sand and <br /> sandy silt)could not be correlated between the Borings. Groundwater was encountered about 62 to <br /> 63 feet below the ground surface during soil boring and well installation activities. <br /> l <br /> GROUNDWATER MONITORING NETWORK <br /> The groundwater monitoring system at the Shadow Lake Mobile Home Community includes the <br /> three monitoring wells (MW-1 through MW-3) shown°in Figure 2. These wells are constructed of <br /> 2-inch diameter PVC and screen the upper 10 feet of first encountered groundwater. The wells were <br /> completed at the ground surface with an at-grade Christy box. Surveyed ground surface and <br /> groundwater elevation reference elevations are shown in Table 1. As indicated:in Table 1c, well <br /> MW-3 had been damaged and was repaired during the September 22, 2005 monitoring event. <br /> However, the reference point for this well has not be re-surveyed and groundwater elevations <br /> reported for this well are uncertain. <br /> r <br /> 4 <br /> C:�A-Proj<_cros ShadowrakeVAmiionarRepomkIQ2010Repan11Q20i0Repon pd - <br /> s <br />