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superimpuscd on ihc soil pr;ssurc tu uccuunt ti�r sirch:irgcs. 1Vc recommcnd assuming a unifom� latcral <br /> press�:re uf 100 psf for cyuipment ,urch:irge, and/ur stacked merchandise. Below-grade walls fur <br /> buildngs should also include scismic carth pressures. Scismic earth pressures should be detemiined <br /> usmo a rectangular�:utribulion of 8i[ in psf, whero H is the wall hcight. <br /> Thesc rccumn:andations are based on the assumption that any retaining walls at this projcct will bc <br /> provided wi;i�adequate drainagc. The valucs for soil bcaring, frictional resistance and passivc resista�icc <br /> prescntc�! abovc for foundation dasign arc applicablc to rc�aining wall dcsign. Nalls locatcd in Icvcl <br /> groun,i areas shuuld ba Ibundcd at,i minimum depth of' IS inches bclow[he adjacen[grade. <br /> :Vall Drainage <br /> Thac pressures assumc thc �vall� arc not subjccred to hydrostatic pressures from watcr building up <br /> bchind the walls. �Vu rccummend that Uie backfill within 2 feet o( the walls consist of free-draining <br /> matcrial. Pree-draining matcrial should consist uf washed 3/3-inch to No. 3 pca gravel or a mixture of <br /> about 30 to d0 perecnt cican medium to coarsc sand and (0 to 70 perccn[ tine gravcl, with Icss than <br /> 3 percent littes (perccnt passing thc U.S. No. 2U0 sicve). '1'hesc walls do nat rcyuirc a perforated colicclor <br /> pipc within thc 1}ce-dr.iining nmtcrial. }lowever, it iti our espericnce that the closure strip Cor concrcte <br /> tilt-up construction projects can become saturaled if Ieft exposcd during constniclion in a'et wca[her. <br /> 'I�I�crefure, wc recommend that petiudic wecpholes be nrade through tiie base of ihe wall immediately <br /> above the looting lo allow watcr in thc clusuro strip tu �lo�v to O�c perimeter footing drain. <br /> Oiher Considerations <br /> i:stcrior rc�aining sy::t�ms utia! to achi�vc �ra�lc transitions or for landscaping, can bc constnictcd usine <br /> tr:�ditianal structural systcros such as rcinforccd cnncretc, C�[U blucks, or rockerics. rVtematively, <br /> retaining walls can consist of reinforecd soil and bluck tacing structures. We can provide additional <br /> design recommcndations for roiuforccd soil and block Greing struchires, if requested. <br /> SIAB-ON-GRADE FLOOR <br /> Subgra�e Preparation <br /> \Vc recammend that concrete slabs-on-grada be cnn;tructed on a gravel layer to provide unifomi support <br /> and drainagc, ;md to act as a capillary brcak. 1Vc csper,t that slab-on-grndc r�ao�s��„n�t����on�a o��n� <br /> n:itivc dense to very �ense till and adv:�nce outwasn deposits encoumcrcd at the site or on properly <br /> cumpacted stnictural till extending do�m to these malcrials. Prior to pl;icing �he g�avel layer, thc <br /> subgradc shuuld bc prooGollcd os dcscribcel pre�iously in Ihe Earthwork section of this' renort. If <br /> � ncccssmv, thc subgradc snould hc rccumpactcd iu :i linn;md unpiclding cundition. <br /> Design Pararr,eters <br /> "I'he gravcl layer beloa' sl:ibs-on-cradc :;huuld cunsist uf (i inches of clean croshed grnvel. wiih a <br /> ❑7:1!(IIt1Uit1 �flCIIJI� sizc of I'!� inchcs ;md nc�lieibl� s;mcl or silt. II'ihe 12-inch-diick working pad laycr is <br /> cunstnicted and if arens contaminated with soil are rcmoved. thcn ihe working pad layer can be used as <br /> ihc capillary brcak laycr described above. Fur slabs dcsigned as a bcam on an clastic foundation, a <br /> mudulus of subgradc rr.iction uf I50 pounds per cubic inch (pci) m�y bc used for subgradc soils prepared <br /> ❑s recommendecl ahove. <br /> If water vapor migntion through the slabs is objectianable, the gravel should be covcred wilh a heaw <br /> pfastic shect, sucli as 10-mil plastic shecting, to act as a vapor rctardcr, as shown on Figure 3. This will <br /> he desirab(c whare the slnbs �viil be surfaced with tile or will be cameted. Tliu contractor should be made <br /> PJrA'u. L'01�5-nill.�:.. -- _-_`'(,_4',Ij—___ .___.___-_.--_—.- GEOENGINEEII� <br /> Januurv_'S.1�]IJS <br />