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r <br />���a <br />��� <br />��� <br />w <br />st <br />o�d <br />�� <br />a� <br />�y <br />M <br />� <br />tlH <br />W y <br />�a <br />`c� �" <br />� <br />I �� <br />� <br />L�� <br />; 7 <br />� <br />� CNA Architecture Group <br />12 Aprii 1991 <br />� <br />W-7352 <br />Page 5 <br />The western margin of the site consisted of relatively steep to near vertical slope. Mest <br />of the slope supported young alder trees, while the steeper regions were bare or <br />covered with intermittent scrub grass and brush. <br />Standing water was visible in many depressions across the site, including a Iz�ge <br />accumulation of water adjacent to stockpiled soils to the south. <br />4.2 Subsurface Cc�ndltions <br />Twelve test pit �xcavations wFre advanced in the vicin�ty of the proposed buildisig for ttie <br />current study. Previous studies included the advancement of test borinys, test pit <br />excavations, and the installation of monitoring wells across the proposed site. These <br />previous subsurface explorations were advanced between October 1989 and August <br />1990, and were performed by Rittenhouse-Zeman & Associates, Inc. Cascade <br />Geotechnical performed explorations at an earlier date, as previously described. <br />The test pits excavated for this study generaliy disclosed 7 to 1 i or more feet of <br />uncontrolled fill present on the site. The Site and Exploration Plan, Figure 1, shows the <br />locations of the test pits excavated on site, and the elevation at which native bearing soils <br />were encountered. This figure also includes test pit and test borings from earlier <br />subsurtace s!udies on property. <br />The fill soils encountered on site ranged from soft relic topsoils to dense granular fills. <br />Based on our explorations, most of the fill material appears adequate to be reused as <br />structural fill if dried to a suitable moisture contents, however, several test pits <br />encountered deposits of organic rich material including stumps, accumulated wood <br />debris, and some burnt organics. Also some test pits encountered metal debris, rubber <br />tires, and other construction debris. <br />4.3 Groundwater Conditions <br />No groundwater was encountered in any of the explorations accomplished onsite. <br />Several zones of wet fiil and native soils were encountered. We suspect that these wet <br />soils are due to the presence of perched water within the fili and native soiis. A perched <br />groundwater condition exists when a horizonl of low permeability soils, typically one <br />containing a high percentage of silt or clay, �estricts the downward flow migration of <br />l� G� ���, <br />� <br />ti <br />