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• ; <br /> Propased Modemization and Additions to Subsurface Explorarion, Geologic Kazards, <br /> Eisenhower Middle Sehoo! and Geotechnica!Engineering Report <br /> Everetr, Wnshington Desi n Recom�nendations <br /> Anticipzted settlement of tbocings founded on approved rock trenches should be on the order of <br /> �/ inch or less. However, disturbed material not removed from footing trenches prior to <br /> footing placement could result in increased settlements. All footing areas should be inspected <br /> by AESI priot to placing concrete to verify that the rock trenches are undisturbed aod- <br /> construction conforms with the recommendations contained in this report. Such inspections <br /> may be required by the governing municipality. <br /> 11.0 LATERAL WALL PRESSURES <br /> Walls that are free tc yicld laterally �t least 0.1 percent of their height shc. . he designed <br /> using "active" equivalent fluid pressures. Fully restrained, rigid walls tha: �ar...ut yield should <br /> be designed using "at-rest" equivalent floid pressures. The following Table 2 provides <br /> appropriate active, at-rest, and passive equivale.�t fluid pressures (and associated friction <br /> coefficients) for the anticipated project wall design conditions. <br /> Table 2 <br /> Retaining Wall Design Parameters <br /> Active At-Rest Passive <br /> Equivalent Equivalent Equivalent <br /> Backslope Fluid Fluid Fluid <br /> Couditions Pressure Fressu-e Pressure Friction <br /> Rock/Soii Ty e (Horizontal:Vertical) ( c�* i c� ( c� Coefticient � <br /> Till Horizontal 30 50 350 0.35 <br /> Till 2H:1 V maximum 60 75 350 0.35 <br /> Structural GII Horizontal 35 55 300 Q30 <br /> Structural fill 2H:IV maximum 65 80 300 0.30 <br /> * pcf = pounds per cubic foot <br /> All backfill behind walls or around foundation units should be placed as per our <br /> recommendations for svucmral fill and as described in this section of the report. Where cast- <br /> in-place retaining walls face strucmral fil;, the backfill should consist of on-site or imporred <br /> granular fill, compacted to 90 percent of ASTM:D 1557. A higher degree nf compaction is <br /> not recommended, as this wifl increase the pressure acting on the wall. A lo�,-er compaccion <br /> may result in settlement of slab-on-grades or other improvements placed ::bove the walls. <br /> Thus, the compaction level is critical and must be tested by our firm during placement. <br /> Surcharges from adjacent footin�s, heavy construction equipment, or sloping ground must be <br /> added to the above values. Auromobile loads may be assumed equivalent to 2 feet of soil. <br /> Jammry 13, 200J qS.COC/dTED E.4RTH SC!£NCES, LVC. �; \ <br /> .i�r:ra-nEo1:JYAJ-Poo�tatCIX'l7J,9iKE11VP- R^K Page 18 U <br />