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Decemhcr 15, 1992 fi 923-118:} <br />Ihe polential for selUemenl. Ntcrnalively in areas of deeper wisuilaUle soils, driven limher <br />piles be used to support thosc Uuildings. "fhe selection o( foundalion type should be based <br />on ihe overall economics of piles versus over-excavalion and replacement of sUuclural fill. <br />Dependin� on Ihe costs of earlhwork and piling, piles generally become m��re economical if <br />the depth of excavalion exceeds about 4 lo G feel. <br />undcrlain by Ihc fill and peal soils. When lhesc soils are rclalivcly shallotv, over-excavalion <br />and mplacernent wilh compacted struclurel (ill is an acceptable alternalive lo pile support. <br />Individual buildings should bc supported enlircly by eilher piles or conventional (ootings due <br />lo Ihe polenlial for differential settletnenl which may rcsull if a building is parlially supporled <br />by eilher of lhese foundalion sysletns. <br />5.2.2 Conv:nlional Sprcad Poolin�s <br />Poolings moy bc used if Ihcy arc (ounded in the nali��e "fill or on struclural fill after thc �, ��`. <br />excavalion of unsuilable soils. Gxcavations to remove unsuitable soils from fooling areas must � <br />be extended outside of thc fooling line a minimum dislance cc�ual lo tlic deplh of the over: /' <br />excavalion. <br />Spread footings should be designecl based on Ihe follotving recommended v7lues: <br />• Maximum Allow:�Ule f3earing f'ressums: 2,500 psf; lhis valuc may bc incrcased <br />by 1/3 for short tenn wind and scismic loadings. <br />. Minimum F.mhedtnenl: <br />Pcrimetcr footings <br />Intcrior footings: <br />. Mininunn Widlh: <br />Isolaled foolings: <br />Conlinuous foolings: <br />. I,aler�l I.oad Resis;ancc <br />18 inches belo�v adjacenl grades <br />12 inches belmv adjacenl grades <br />21inches <br />18 inches <br />Allo�vablc Passivc resistancc: 250 pc(, r:�����,i�„� n����i <br />Cocf(icient of I�riclion: 0.4 <br />Nol_: 'I�he InE� (ool of deplh shauld be ne�lecled in design compulalions of the <br />passive capacity unless lhe soil is con(ined beneath a pavemenl or slab. <br />Gstimaled Sclllemenl: <br />"1'olal Seltlenunt: 1/2 inch <br />Di(fcrenlial Selll�ment: 1/4 incli <br />Golder Associates <br />