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 III. DESIGN RECOMMENDATIONS 8.0 INTRODUCTION Our explorations indicate that, from a geotechnical standpoint, the parcel is suitable for the proposed development provided the recommendations contained herein are properly followed. Based on our explorations, the foundation bearing stratum is relatively shallow across the site and conventional spread footings may be utilized for foundation design. Mass grading at the site will require careful planning around the prevailing weather conditions at the time of construction. The on-site native soils are highly moisture-sensitive and should only be considered feasible for reuse as structural during the drier summer months, typically between July and September. Alternative grading techniques such as cement treatment of on-site native soils or the use of an import free-draining structural fill should be planned for during the wet season, typically from October to June. Our recommendations for site preparation, structural fill, building foundations, slab-on-grade support, drainage considerations, retaining wall considerations, pavements, and infiltration feasibility are provided in the following sections. 9.0 SITE PREPARATION 9.1 Clearing and Stripping All topsoil, vegetation, and any other deleterious materials should be stripped from the proposed building and pavement areas. Areas where loose surficial soils exist due to grubbing operations should be considered as fill to the depth of disturbance and treated as subsequently recommended for structural fill placement. Any existing fill soils located below the building area should be stripped down to the underlying, medium dense to very dense lodgement till sediments. 9.2 Temporary and Permanent Cut Slopes In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction based on the local conditions encountered at that time. For planning purposes, we anticipate that temporary, unsupported cut slopes within the dense to very dense glacial sediments can be planned at a maximum inclination of 1H:1V (Horizontal:Vertical) or at 1.5H:1V within loose to medium dense fill or native sediments. Flatter inclinations may be recommended in areas of seepage. As is typical with earthwork operations, some sloughing and raveling may occur, and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. Permanent cut or fill slopes should not exceed an inclination of 2H:1V. December 17,2021 ASSOCIATED EARTH SCIENCES,INC. PEL/Id-20200319E001-002 Page 10