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Gcotcclmicnl Engiurcring 8vnluation <br />l303 Madrona Avc - King <br />December 2, 2006 <br />RM; �ileNo.3930L <br />Page 8 <br />ro�,��d:�r�o��s <br />Conventionnl shallow spread foundations sBould be placed on undisturbed mzdium dense or better nativc <br />soils. Where Icss t:ian mcdium densc soils are encountered nt footing beetring elevntion, tlie subgrade <br />si�oulJ be ovcrexcavatcd to expose suitnble bearing soil. The overcxcnvntion could be filled �viP• <br />slmctural fill (see subsection on Structural Fill) or [he footing may bc extcnded do���� ro thc beariag <br />native soils. If footings nre supportcd on structurnl fill, the fill zone should extend oulside lhe edges of <br />tha footing a distac:e equal to tl�e dcpth of ovcrcxcavation below tlie footing. Footings on Uie existing <br />slope are reryuired ta be xt such depths so that tl�c faces of the footings nre no closcr than 9 feet to <br />the fnce af thc slopc. Tootings tar rateiniug �r•ulls should 6c nt Icnst 12 feet frnm tLe fece of thc <br />slnpc. <br />I'ootings includiug interior footings shauld cxtend at Icnst 18 inclies below thc lowest adjncent tinished <br />ground surfnce ior frost protection and/or bearing a�pacity conside�ations. Minimum foundation widths <br />of IS and 24 inches nre recommended for continuous and isolated spread footings, respeotively. <br />Stnnding �vater should not be allowed to accumulate in footinF trenches. All toose or disturbcd soil <br />should be removed from the Poundation excnvation prior to pouring of the concrctc. <br />For foundntions constructcd ns uu[lined aUove, we recommend nn nllowable design benring pressure of <br />not more thnn 2,000 pnunds per square foot (ps� be uscd for [I�c footing desi�i. Current Intemntional <br />Building Codc (IBC) guidelines should bc used �vlten considcring increased allo���able benring pressurc <br />£or short-term transitory wind or scismic loads, ?'otential foundation sctllcme�zt using the recommended <br />allowablc benring pressure is estimntcd to bc Icss than 1 inch total and l/2-inch differenYial behveen <br />ndjacent foor.ngs or ncross u distnnce of �bout 25 feet. <br />Laternl londs mny be resisted by friction on the base ;.f dic footing and pnssive resistance against thc <br />subsurface portions of the foundation. A coefficicnt of friction of 035 may be used to calculntc Ihe base <br />friction, and should bc applicd to the vertical dead loed or,��;. Passive resistance may bc calculated as � <br />trianguinr equivnlent fluid pressure distriUution. An equivnlent fluid density oP 200 pounds per cubic <br />foot (pc� should bc used for pnssive resistnuce design. These recommended values incorporate saFety <br />fncrors of LS und 2.0 applicd to the estimated ultimnte vnlues for fri��tionul and passive resistance, <br />rrspectively. To uchieve this valuc of passive resistnnce, the foundntions should be pl::ced "nc;�f' <br />fnithout form>) aeninst t.he n�tive medium dcnse or better soils or compncted snil should be placed <br />RI'dl ASSOCIATES LLC <br />OT'� GST9-6Z9 (D9E1 51oez:4��FJ PIN su2[saQ dLS�ED LO 60 �eW <br />