1010 N BROADWAY STARBUCKS Geotech Report 2025-07-24

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