10730 19TH AVE SE 2018-01-02 MF Import

s W. T. Duzyea Company JN 87105 May 20, 1987 Page 4 the requitements of structural fill . A coefficient of friction of 0. 45 may be used between the structural foundation concrete and the supporting subgrade. The passive resistance of undistutbed natural soils and well compacted fill may be taken as equal to the pressure of a Pluid having a density of three hundred fifty (350) pounds per cubic foot (pcf) . SLAB-ON-GRADE FLOORS Slab-on-grade floors may b�a supported on undistuzbed native soils or on structural fill. 'i'he slab shoulc� also be pzovided with a minimum of four (4) inches of fr�ae dzaining sand or gravel. In areas where moisture is undesirable , a vapoc .barrier such as a 6 mil plastic , membrane should be p].aced beneath the slab. PERMANENT RETAINING AND FOUNDATION WALLS Retaining and foundation walls should be designed to resist lateral earth pressures imposed by the soils zetained by these structures. Walls that are designed to yield an amount equal to at least 6. 002 times the wall height can be designed to resist the lateral eazth pressure imposed by an equivalent fluid with a unit weight of thitty-five (35) pounds pet cubic foot (pcf) . If walls are to be restrained at the top fzom free movement, a � uniform force of one hundred (100) pounds per square foot (psf) should be added to the equivalent fluid pressure force. For calculating the base resistance to sliding, we recommend using a passive pressure equivalent to that exerted by a fluid having a density of three hundred fiftx (350) pcf and a coefficient of friction of 0. 45. It is assumed that no hydtostatic pr.essuzes , � act behind the wall and that no suzcharge slopes or loads will be placed above the walls . If surchacges are to be applied, they should be added to the above lateral pressuces . I Retaining and foundation walls should be backfilled with ' compacted free-draining granular soils containing no organics . The wall backfill should contain no more than 5 percent silt oz clay and no particles gteater than four inches in diameter. The percentage of particic�� passing the No . 4 sieve should be between 25 and 70 pecc�ant . Alternatively, a geotextile diainage product such as Miradrain or Enkadrain may be used . The puzpose of this is to assure that the design criteria for the zetain:ng wall is not exceeded because of a build-up of hydrostatic pressure behind the wall . GE07'F:CH CONSUIlI'ANTS INC.