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Geotechnical Engineering Evaluation lierracon <br /> Broadway& 10th Starbucks Everett, WA <br /> January 9, 2014 Terracon Project No. 81135080 <br /> Minimum Thickness <br /> Flexible Pavement Layers Parking Lot& Light-Truck <br /> (top to bottom) Drive-Thru Driveway <br /> Asphalt Concrete Pavement (ACP) 3 inches 3'/z inches <br /> Crushed Aggregate Base (CAB) 3 inches 4 inches <br /> Granular Subbase (GSB) 6 inches 8 inches <br /> Rigid Pavement Sections: A rigid pavement section typically comprises a cement concrete <br /> pavement (CCP) over a crushed aggregate base (CAB) over a granular subbase (GSB). <br /> Although the GSB can be omitted in certain cases, we infer that it is beneficial at this site in <br /> order to mitigate the moisture-sensitive subgrade conditions. Our recommended minimum rigid <br /> pavement sections, which are based on the aforementioned design values, are shown below. <br /> Minimum Thickness <br /> Rigid Pavement Layers Parking Lot& Light-Truck <br /> (top to bottom) Drive-Thru Driveway <br /> Cement Concrete Pavement (CCP) 5 inches 6 inches <br /> Crushed Aggregate Base (CAB) 2 inches 2 inches <br /> Granular Subbase (GSB) 6 inches 8 inches <br /> Subgrade Preparation: All pavement subgrades should be compacted to a firm and unyielding <br /> condition before any pavement layers are placed. We recommend using a vibratory roller in <br /> granular (sand or gravel) subgrade areas and a static roller in cohesive (silt or clay) subgrade <br /> areas. Any encountered zones of very loose fill soil will require additional compactive effort to <br /> achieve an adequate density. After all subgrade areas have been compacted, the resulting <br /> subgrade condition should be verified by proof-rolling with a loaded dump truck or other heavy <br /> construction vehicle, in the presence of a geotechnical representative. <br /> Granular Subbase: We recommend that all GSB material consist of imported, well-graded <br /> sand and gravel, such as "Ballast" per WSDOT: 9-03.9(1). In the interest of using recycled <br /> materials from on-site or off-site sources, it would be acceptable to substitute up to 20 percent <br /> of the GSB with crushed asphalt concrete or up to 100 percent of the GSB with crushed cement <br /> concrete, provided that the final mixture meets the same textural criteria as the aforementioned <br /> WSDOT material. Existing onsite granular fill soils encountered in our borings will likely be <br /> suitable for reuse as granular subbase, though care should be taken during grading operations <br /> to not mix the granular fill soils with the underlying silty sands. Regardless of composition, all <br /> GSB material should be compacted to a minimum density of 95 percent, based on the Modified <br /> Proctor maximum dry density (per ASTM: D-1557). <br /> Reliable Responsive - Convenient _ Innovative 12 <br />