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

Kctaioing Wall Construction In ordcr to creatc a Icvcl building pad for thc planncd residcncc, it will bc neccssary to conswct a rctaining wall(s) across thc lowcr porlion of the north and cast sides of thc property. 'Chc mtaining walls will stcp up and bc kcycd into the northcast sloping ground surfacc. Thc typc oC wall currcndy under considcration is a scgmcntal block wall with an associatcd mechanically stabili7�ed carth (MSG) fill. MSE fills are self-supporiing duc to intcrnal rcinforcement with horizontal layers of geogrid. 7�c emt�cddcd geogrid provides the intemal strength to support thc fill and the scErnenlal block wall facing pmvides thc long term crosion control for the near vertia�l fill facc. The gcogriA rcinforcui walVfill will bc capable of providing suitable support for the planned residencc and will also greaQy reducc the potcntial for future movement of thc existing slopc sedimcnLti. A typical desigr�det:ul for the plannc Wall design caleulations an:also included. "I'hc actual wall or walls locations have not becn finali-r.cd at tl�c time of this rcport. Wc anticipatc that one tall wall or two smaller walls may be necessary to create the grades necessary to support Uie residencc and garagc foundaUons. Becausc of thc significant gradc difIercncc bctwccn Ihe access off of Broadway to die low point of the planncd devclopment arca, we anticipatc that multiplc wall locaUons may be nccessary to achievc (hc requircd level benchcs fo support thc planned devclopmrnt. The current wall design allows for a 3H:1 V slope betwccn thc top of a lower wall and thc toc of the next wali or housc foundation above. Thc upper wall basc or foundation must lx; a minimum of 10 fect horizontal in back of the back of thc lowcr wall blocks and if a slopc is maintained between thc lowcr wall and upper structum, a minimum of 3 fcct away fram the upper svucturc thc slope must Ilattcn to horizonk�tl. All sloping ground betwecn swctural clemen�s must be placed and compacted as previously discussed for swcturdl fill. Wc strongly rccommcnd lhat thc final housc, garagc and rclaining wall locations and grade catchcs bc reviewai by E3GC, pllc once these plans are availablc to verify that the surcharges and wall hcights are consistcnt with the preliminary wall design. It is also �ssible that anothcr ty�x of mtaining wall may bc chosc.n to provide gc-adc scparalion. Wc arc availablc � to provide s�x�cific geotechnical dcsiE;n considerations for othcr typcs of rctaining wall once plans an availablc. Instal]ation of the M115G wall should begin hy cxcavating a horizontal bearin;,pad for lhe waJl foundation and reinCorccd fill. The foundation excavzition muy step vertically along iLs Iength, but il is essential Uiat the w:ill blocks and geogrid reinforced fill be placed on horizonGnl pads cut into the densc, nativc scdiments bcncath Uic topsoil and wwthered zonc. 71ic undisturbcci, densc native sediments will bc capablc of providing llre requircd 340Q psf h�:�rin�;capacity fnr support of thc wall. 7hc bazc row of w;�l block nccds to maintain a minimum of 24 inches of embcdment at all locations�ilong thc wall base. 'I'hc prepnrcd subgradc should lx; evaluated by a represcntative of U�is firtn prior to placing the base wall blocks to verify suitable foundation bcving conditions for the wall. Oncc ilic subgradc has bccn prcpared and approved by lhe gcolechnical engincror, the basc wall blocks may b�sct. 'The base blocks should be set on a levcling course of 5/8 inch crvsheci rock. With thc base btocks set, thcir alignment should be checked and the first layer of backfill placed and compactcd. The fill soil placcd behind the wa11 should be mineral soil fine oCorganics. "Ihe backfill should be placecl in maximum S inch loose lifts and cach IiR shall be compacted to a minimum of 95 percent of the modified Proctor maximum ciry density per ASTM:D-1557. llie first laycr of gcogrid reinforcement will be placed atop thc base row of blocks. 'i'hc length of DGC,pllc 14267 209'" Avenue NG, Woodinville, WA 98077 (425) 273-5062