6202 ASSOCIATED BLVD Geotech Report 2022-10-25

Proposed Everett Warehouse ZipperGeo Project No. 2152.01 March 5, 2019 For heavy-duty pavements (main access and travel paths, truck delivery areas, etc.), we recommend 3 inches of asphalt concrete over 6 inches of crushed rock base course. Materials and Construction: We recommend the following regarding asphalt pavement materials and pavement construction. • Subgrade Preparation: We recommend, at a minimum, the upper 12 inches of pavement subgrade be prepared in accordance with the recommendations presented in the Subgrade Preparation section of this report. • Asphalt Concrete: We recommend hot mix asphalt consist of Class B hot mix asphalt. • Base Course: We recommend that the crushed aggregate base course conform to Section 9- 03.9(3) of the WSDOT Standard Specifications. • Compaction: All base material should be compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM: D 1557. We recommend that asphalt be compacted to a minimum of 92 percent and a maximum of 96 percent of the theoretical maximum density. Concrete Pavements: Concrete pavement design recommendations are based on an assumed modulus of rupture of 600 psi and a minimum compressive strength of 4,000 psi for the concrete. For concrete pavement areas, we recommend a minimum of 5 inches of concrete over 3 inches of crushed aggregate base. Although not required for structural support, the aggregate base layer is recommended to help reduce potentials for slab curl, shrinkage cracking, and subgrade "pumping" through joints. Given the recommended thickness of the concrete pavements, we recommend the pavement have relatively closely spaced control joints on the order of 10 feet. CLOSURE The analysis and recommendations presented in this report are based, in part, on the explorations completed for this study. The number, location, and depth of the explorations were completed within the constraints of budget and site access so as to yield the information to formulate our recommendations. Project plans were in the preliminary stage at the time this report was prepared. We therefore recommend Zipper Geo Associates, LLC be provided an opportunity to review the final plans and specifications when they become available in order to assess that the recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design. The performance of earthwork, structural fill, foundations, and pavements depend greatly on proper site preparation and construction procedures. We recommend that Zipper Geo Associates, LLC be retained to provide geotechnical engineering services during the earthwork -related construction phases of the project. If variations in subsurface conditions are observed at that time, a qualified geotechnical engineer Page 16