5402 25TH AVE W 2016-01-01 MF Import

- • City of Everett � . � c/o Ron and Kelly Krueger � August 22, 2007 . Page 4 SLABS-0N-GRADE: Slab-on-grade floors may be supported on undisturbed, competent native soils or on structural fill. The slabs may be supported on the existing soils provided these soils can be re-compacted prior to placement of the free-draining sand or gravei underneath the slab. This sand and gravel layer should be a minimum of four (4) inches thick. We also recommend using a vapor barrier such as 6-mil. piastic membrane beneath the slab with minimum overlaps of 12 inches for sealing purposes. PERMANENT FOUNDATION AND RETAINING NIALLS: Retaining walls backfilled on one side on�y should be designed to resist lateral earth pressures imposed by the soils retained by these structures. The following recommended design parameters are for walis less than twelve (12) feet in height, which restrain level backfill: Parameter Desiqn Value Active Earth Pressure* 35 p.c.f. Passive Earth Pressure 350 p.c.f. Coefficient of Friction 0.55 Soil Unit Weight 125 p.c.f. Where: (1) p.c.f. is pounds per cubic foot (2) Active ar.d passive earth pressures are computed using equivalent fluid densities. * For restrained walls which cannot deflect at least 0.002 times the wa11 height, a uniform lateral pressure of one hundred (100 p.s.f. should be added te the active equivalent fluid pressure). , The valuss given above are to be used for design of permanent foundation and retaining walls only. Ar� appropriate safety factor should be applied when designing the walls. We recommend using a safety factor of at least 1.5 for overurning and sliding. The above design values do not include the effects of any hydrostatic pressures behind the walls and assume that no surcharge slopes or loads will be piaced above the walls. If these conditions exist, then those pressures should be added to the above lateral pressures. Also, if sloping backfill is desired behind the walls, then we will need to be given the wall dimensions and slope of the backfill in order to provide the appropriate design earth pressures. l 1