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January 28, 2005 <br /> Project No.T-5659 <br /> � <br /> The appropriate pavement section is dependent upon the supporting capabiliry of the subgrade soils and the tra�c <br /> i conditions to ��-hich i[ will be subjected. �Ve�nderstand that traffic will mainly consist of light passenger vehicics <br /> � and large commercial tractor-trailer trucks. <br /> I Qased on this infoanation, widi a stable subgrade prepared as recommended, we recommend the f'ollo�ti�ing <br /> pavement section for heavy traCfic areas: <br /> ,I • Three inches of asphalt concrete(AC)over six inches of crushed rock base(CRB) <br /> ! • Three inclics of AC over four inches of asphalt-treated base(ATE3) <br /> iFor light traffi�arcas,the following pa��ement scetions arc recummended: <br /> • Two inches of AC over four inches of CRLi <br /> � • Two inches of AC over thrce inches of Al'13 <br /> The paving materials used should conforn to the 2004 �Vashington State Depanment of Transportation <br /> i (���SDOT)specifications for %-inch hot mix asphalt(IilvtA), ATQ,and CRB surfacing. <br /> 'I'hc reconunended light and i ;avy traffic sections would support design I S-kip equivalent single axle loads <br /> ii (CSALs) of 50,000 and 500,000, respectively. These GSALs represent traffic loading equivalent to 4 and 24, <br /> loaded (80,000 pound gross vehicle weieht) tractor-trailer rigs, respectively, traversing tl�e pavement per day over <br /> a 20-year design lifc. If heavier traffic loading or volumes are espected, we should re•evaluate the required <br /> Ipavement sections. <br /> f <br /> Lo��g-term pavement perfonnance will dcpend on surface drainage. A poorly drainecl pavement section will be <br /> � subject to prcmature failure as a result of surface �,vater infiltrating into the subgrade soils and reducing d�eir <br /> supportina capability. For ��ptimum performance, we recommend surface drainage gradients of at least hvo <br /> percent. Some dcgree of longitudinal and trans��erse cracking of the pavement surface should be expected over <br /> � time. Regular maintenance sUould Uc plvmed to seal cracks�vhen they occur. <br /> � 5.0 ADDITIONAL SER�'1CGS <br /> Terra Associates, Inc. should revie�v the final project designs and specifications in order[o verify that earthwork <br /> and foundation recommendations have been properly interpreted and incorporated into project design. Ne should <br /> � I also provide geotechnical services during constniction to obsen�e compliance with our design concepts, <br /> specifications, and recommendations. 1'his will allow for espedient desien chanaes if subsurface conditions differ <br /> II 1�om thosc anticipated prior to [Itc start of constructien. <br /> ! <br /> 6.0 l,l��t17'ATIONS <br /> I <br /> I �Ve prepared this report in accordance �eith generally accepted geotechnical engineering practices. No other <br /> warranty, expressed or implicd, is made. This repon is the copyriglited property oCTerra Associates, Inc., and is <br /> � intended for specific application ta the Nfuuntainvicw Business Center - Lots 3, 4, and 5 project in Everett, <br /> � �Vashington. This report is for the exclusive use oC Latitude Devcloptnent, L:,C and ttteir authorized <br /> representatives. <br /> � <br /> Pagc No. 3 \�� <br /> Y <br /> I � <br />