4728 COMMERCIAL AVE 2016-01-01 MF Import

, Robcrt Kincaid Junc 27, 2007 Page 6 SLABS ON GRADE Floor slabs can be supported on native soiis if srte preparation is accomplishc� as previously recommended, or can Uc supportcd by stnictural CIL Thc subgrade soils should be compacted using vibratory cquipment or rcplaced with compac:Ad structural fill if loose areas are observed. A base course layer consisting of G inches of clean, free-draining sand or gravel containing no more than 5 percent fincs should be placcd beneath the Floor slab to provide uniform support and a capillary brcak. A suitable vapor barcier, such as heavy plastic shecting, should be placcd ovcr thc capillary brcak. SUBSURFACE WALLS The bascment�valls for thc proposcd residcnce function as rctaining walls and should be designed as such. For design oF retaining walls at the ��te, assuming tha[ the walls that �re allowed to deflect 0.001 titncs thc hcight of thc wall, wc rccommend an active lateral pressure equivalent to a tluid dcnsity of 35 pounds per cubic foo[ (pc�, assuming level backfill compacted and diained as outlined bclow. If the backfill surface slope� >stecper than 2I-I:l V upward away from the wall, a lateral soil pressurc value of 65 pcf should be uscd. Othcr valucs may be appropriate depending on geometry and surcharge conditions;we can providc rccommendations for othcr specifc conditions if nccded. Resist:mce to lateral footing loads can be dc��cloped both through friction on the base of the footings and passivc pressures along the sides. Friction resistance on the basc of the footing bc computed using a coefficicnt of friction of 0.45 applied to the vertical dcad load torces. Passive soil pressures may be computed using an equivalent fluid pressure of 260 pounds per cubic foot, providing thc backfill around footings is compactcd to at Icast 95 percent of inaxitnum dry density (r\STM D-1557). These resistance vcilues include a factor of safcty of about 1.5. Thc above latcral soil presstu�cs as�ume thc walls will be backfilled with dean, frec- draining sand or sand and gravel containing less than 5 percent fines (matcrial passin� thc No. 200 sieve). This drain:tge zone should be at least 1S inchcs thick horizontally. The dr.iinagc material and remainin�backfill piaced bchind the wall and not supporting structural cicmcnts should bc compactcd to approximately 90 perccnt oP the masinwm dry density. [Icavy compaction cquipment should not bc operated within 3 fcet of thc retaining walls. A permancnt subsurface drainagc system should be installcd at thc base of all subsurface �valls. These subdrains should consist of rigid, smooth-wall, 4-inch-diameter (minimtun) perl'oratcd PVC pipc, wrappcd with nonwovcn filtcr fabric such as Mirafi draina?c product // orcqual,and surrotmdcd by pca gravel or wcll-graded gravclly sand or sandy galvcl with Icss p D / 7505 Wesl Lake Sammamish Parkway Northeasl Redmond,Washinc�ton 98052 425-Bd2•4850 w�nv.Wbbs.Com