6801 SEAWAY BLVD Geotech Report 2025-08-19

Seaway Commercial Center Subsurface Exploration,Geologic Hazard, 7007 Seaway Boulevard and Geotechnical Engineering Evaluation Everett, Washington Design Recommendations be replaced with 5/8-inch crushed rock as a leveling course, if desired. The crushed rock base course should be compacted to a minimum of 95 percent of the maximum dry density per the ASTM D-1557 modified Proctor. • For heavy-duty concrete aprons, we recommend a preliminary section that consists of 8 inches of Portland cement concrete pavement (PCCP) over 4 inches of 11A-inch crushed rock base course meeting WSDOT Standard Specifications. For light-duty asphalt pavements, we recommend a preliminary section that consists of 3 inches of 1/2-inch HMA over 4 inches of 11/4-inch crushed rock base course. Crushed base course material may be substituted with ATB to form a working surface beneath the final asphalt surfacing. The substitution of ATB should be as follows: 4 inches of crushed rock can be substituted with 3 inches of ATB, and 6 inches of crushed rock may be substituted with 4 inches of ATB. 16.0 STORMWATER INFILTRATION FEASIBILITY Lodgement till soils were encountered in all exploration pits onsite to the termination depth which ranged from 5.5 to 10 feet. Additionally, exploration boring EB-1 encountered dense to very dense lodgement till soils to the termination depth of 51 feet. The permeability of lodgement till sediments is typically on the order of 1 to 2 inches per month due to high silt content and high relative density. Therefore, it is our opinion that stormwater infiltration is not feasible for the site. 17.0 PROJECT DESIGN AND CONSTRUCTION MONITORING We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. If significant changes in grading are made, we recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundations depends on proper site preparation and construction procedures. In addition, engineering decisions may have to be made in the field in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know, and we will prepare a proposal. December 17,2021 ASSOCIATED EARTH SCIENCES,INC. PEUid-20200319E001-002 Page 17