304 SE EVERETT MALL WAY PANERA BREAD Geotech Report 2025-07-25

KA No.092-12004 August 24,2012 Page No. 5 Additional seismic considerations include liquefaction potential and amplification of ground motions by soft soil deposits. The liquefaction potential is highest for loose sand with a high groundwater table. The native soils consisting of medium dense to very dense silty sand with gravel interpreted to underlie the site are considered to have a low potential for liquefaction and amplification of ground motion. CONCLUSIONS AND RECOMMENDATIONS General It is our opinion from a geotechnical standpoint that the site is compatible with the planned development, provided that our recommendations are incorporated into project plans and are implemented during construction. Our subsurface explorations generally encountered a variable amount of undocumented fill and organic material overlying medium dense to very dense native soils. In general, medium dense to very dense native soils were encountered near the surface in the eastern portion of the site, and at a depth of approximately 10 feet in the western portion of the property. In our opinion, the medium dense to very dense native soils should provide adequate support for foundations,slabs,and pavement. We recommend that foundations be supported on the underlying medium dense or better native soils. This could be achieved by means of removing the unsuitable materials in planned footing areas and replacing with structural fill. Alternatively, the foundations could be supported by piling that extends through the soft soils and into the underlying dense to very dense native soils. If some settlement, cracking and maintenance of the slab is acceptable for this project, then the slab could be supported on at least one foot of granular structural fill placed over the variable amounts of undocumented fill and organic materials underlying the site. If settlement, cracking and maintenance of the slab is not acceptable for this project, then the unsuitable soils should be removed to expose the competent medium dense or firmer native soil and structural fill should be placed to support the slab. Alternatively, the slab could be supported on piling. The pavement section should be constructed on native soil or on a layer of Mirafi 600X or equivalent geotextile and at least one foot of structural fill. The soils encountered in our explorations on site are generally considered to be moisture-sensitive. Silty soils typically do not perform well when wet. The non-organic on-site soils could be used as structural fill provided the moisture content is near optimum and they could be suitably compacted to project specifications. This will depend on the moisture content of the soils at the time of construction. Construction during extended periods of wet weather could result in the need to remove wet disturbed soils and import all-weather materials, resulting in greater project expenses. Krazan and Associates is available on request to evaluate the suitability of the on-site soils for use as structural fill material at the time of construction. Krazan&Associates,Inc. Eleven Offices Serving The Western United States