5505 BROADWAY RECORDS STORAGE ONLY 2016-01-01 MF Import

the gcvyid, as mcasumd from thc back of the wall block, will bc 14 fcct long for thc maximum cxposed wall height of I G fceL Qf conditions or grading changes rcquirc wall hcights grcatcr than 16 fcxt, thc wall design enginccr, I3GC, pllc should be contacted to provide a dcsign rcvision.) As thc wcst wail steps up the slopc Gom the low at lhc northeast corner, the grid Icngths may bc shortened to 80 perccnt of thc wall hcight as the wall hcight decreases. 7�he geogrids must be placed horizontally and at thc proper intcrvals as spccificd on ihe wall secuon dctail. The maximum vertical spacing bctwcen laycrs of geogrid reinforccmcn[shall bc 24 inchcs. Thc minimum 24 inches of cmbcdment material in front of lhc wall :nust bc excavatcd dow�n into nativc sedimcnts and thc excavation shall be cut as close to the facc of the wall as possiblc such that minimal space betwecn the H�al) batc and the cmbedment soil occurs. T7�c manufacturcr's rccommendations for placing and asscmbling wall blocks should bc followccl at all timcs. Thc procc:ss of placing rows of walls blocks, placing drain rock, backGlling and compacting thc fill, and placing laycrs of�cogrid reinforccmcnt will bc repeatcd until achieving the planned wall hcight. Pach layer of geogrid should be tcmporarily stakcd to a taut condition prior to placing soil backfill on top of it. Kccping the gcogrid taut will reduce the potential for post construction wall movemcnt. The gcogrid chosen for the w:ill analysis was Stratagrid 500 a�d Keystone wall blocks. Other gcogrid and block manufacturers are acccptablc; I3GC, pllc should bc conlactcd to approve an cyuivalent strength gcogrid from thc choscn brand and vcrify acceptabi!ity with thc prescntcd wall design. The approximatc 12 inch zonc immcdiatcly bchind thc wall blocks will consist of drsin rock. 'i'his drain rock shall be cican, frec-ciraining,crushed rock with a maximum diametcr of 1'/. inches. 1'rec-drainin6 is definecl a�s less than 5 perceot passing the No. 200 sicve when mensurcd on the minus N4 Gaction of the total. Pca�-avel or round, washcd drain rock may not bc used in this wall drain zonc. A 4 inch diametcr perforateJ clrain pipc should bc embeddcd at tre base of diis drainagc column of rock Thc pipc dischargc should bc out thc face or around thc cnd of thc �r.ill at Ihe low point (or poinLS) of thc foundation cxcavation. The discharge should thcn be tightlined to Uic toc of the slope. If onsitc wils arc used for swctw3l fill within thc wall back(ill zone, it will be n��cessary to cstablish a sccondary"chimney drain" behind thc minforccd fill. if a cican, fre;c-cir.uning, imported s.v�d and gravcl is uscd to construct Uie minforced wall fill the chimney drain will not be necessary. The need for a secondary drnin will bc dctemiincd at Uic timc of construction bascd o� the pc�entage of fines in lhe wall backfill � soil bcing uscd. 'llic constrvction of thc wall should bc completed Uy a contractor with expericncc in conswction of sc�nenlal block w�ill systerns. The sWctival intcgrity dcpcnds on proper placcment of wall system com�wnenLs mid compaction of Ihe wall backfill. A rcpresentative of this firm should provide ovcrsight during construction to verify compliancc with Uie dcsign detail :uid for yuality control purposes. It will also be neccs�ry to have a testing labontory provide in-situ density tcsts to vcrify the structutal compaction of thc backtll. It should also be understood uiat all se�nenta! block walls move some small amount laterally atter conshuction. This movcment is neccssary to achicve the passive carth pressurc bctwea;n the struclural fill soil and thc gcogrid reinforcement. iateral wall movemcnt of about 1 perccnt of thc wall hcight may occur, tyQically during thc first ycar aftcr complction of thc wall. (3GC, pllc 142G7 209w Avenuc NG, Woodinvillc, WA 98077 (425) 273-5062