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603284-001 <br />2.2.1 Undocumented Artificial Fill: (Afu) <br />Artificial fill of varying thickness likely blankets most of the site. Within the <br />borings excavated as part of this exploration, we encountered fill depths <br />ranging from 3 to 5 feet bgs. The fill soils consisted of stiff, fine grained, <br />dry to moist, sandy silt to medium dense, fine to coarse grained, dry to <br />moist sand to silly sand. Localized deeper fill should be expected in the <br />areas around the existing buildings and in the area of previous <br />underground storage tanks (Athanor Environmental Services, Inc., 2011). <br />2.2.2 Quaternarv Fluvial Deposits (Qvfj <br />The Quatemary age fluvial soils encountered onsite consist predominately <br />of sands of the Santa Ana river drainage. The predominant near-surface <br />material encountered was a brown to light yellow brown, thinly bedded to <br />massive, loose to medium dense, dry to moist, fine to coarse sand with <br />varying proportions of silt with sub-rounded to well-rounded gravel. <br />Locally soft to stiff, thinly bedded to laminated, brown to olive brown, moist <br />to wet sandy clayey silts to fat lean clays were also encountered. <br />2.3 Geologic Structure <br />Geologic structure of fluvial and floodplain soils is anticipated to be generally <br />thickly bedded to massive; however, it can be interpreted that cross-stratification, <br />channel trough cross-stratification, transverse bar-tabular cross-stratification, thin <br />bedding and laminated sedimentary structures can exist at depth. These <br />sedimentary features are characteristic of aquitards and contain potential to <br />perch groundwater. Our interpretation of subsurface stratigraphy is presented on <br />Figures 4 and 5, Generalized Geotechnical Cross Sections A-A' and B-B', <br />respectively. <br />2.4 Groundwater <br />Perched groundwater was encountered in borings B-1 and 8-6 at approximately <br />25 feet bgs within thinly bedded silty strata. Groundwater was encountered in all <br />borings at depths between 32 and 40 feet bgs with the exception of the shallow <br />borings, B-8 and B-9, drilled to depths of 5 and 10 feet bgs. The following table <br />lists the borings, depth to perched groundwater as encountered during drilling, <br />-7- <br />Leighton