7200 HARDESON RD 2016-01-01 MF Import

r . f 3 CNA Architecture Group 12 April 1991 r ' W-7352 Page 10 5.4 Slab-On-Grade Floors We understand that development of this parcel will include slab-on-grade floor construction. The subgrade to support the ground level floor slab should be prepared in accordance with the previous Site Preparation recommendations (Section 5.1). The slab-on-grades should be founded on a pre-rolled mediuAsd� D-1557ens�e t� reviously structural fill compacted to at least 95 percent density ( )• P placed fill soils shou�.i experience less than �/z inch of post construction slab settlement, if placed according to the referenced compaction. We recommend that the floor slab be underlain by at least 4 inches of clean, washed rock, or pea gravel to serve as a capillary break and working surface. Additionally, an underslab impervious moisture barrier should be utilized to protect the slab from dampness. If the base of the floor slab is set at or below adjacent exterior grades, perforated pipe perimeter drains should be installed around the building foundations as outlined in the Drainage Considerations section of this report. 5.5 Backfflled Walls Ali backfill placed behind walls or around foundations should be placed as per our recommendations in Structural Fill (Section 5.2), Drainage Considerations (Section 5.6), and as described in this section of the report. The following recommended earth pressures are presented as equivalent unit weights and are based on the assumptions of a uniform, level, granular backfill without buildup of hydrostatic pressure behind the walis. To minimize lateral earth pressures and prevent the buildup of hydrostatic pressures, wall backfill should consist only of free draining granuiar material with drainage provisions as discussed in the subsequent Drainage Considerations section of this report. We recommend that all backfill within 24 inches of the wall consist of a well graded sand and gravei or washed gravel cantaining less than 5 percent fines passing the U.S. No. 200 Sieve, when based on the minus No. 4 Sieve fraction. If the backfilled walls are structurally restrained from lateral movement at the top, during compaction of the wall backfill soiis, we recommend that they be designed for an equivalent we'ght of 55 pounds per cubic foot (pc� to represent at rest pressure. If the tops of the wells are free to move lateraliy by an amount equal to at least 0.01 percent of the wall hei�ht during fill placement construction, they may be desiyned for active conditions using an . : �m� 2 a s