1515 132ND ST SE Geotech Report 2022-10-25

Proposal for Geotechnical Engineering Services Proposed Bank: 1515 132"d Street Southeast, Everett, Washington March 15, 2019 5.2.1 Lateral Resistance Lateral loads on the structure may be resisted by passive earth pressure developed against the embedded portion of the foundation system and by frictional resistance between the bottom of the foundation and the supporting subgrade soils. For footings bearing on the dense to very dense silty sand, a frictional coefficient of 0.35 may be used to evaluate sliding resistance developed between the concrete and the subgrade soil. Passive soil resistance may be calculated using an equivalent fluid weight of 350 pcf, assuming foundations are backfilled with structural fill. The above values include a factor of safety of 1.5. Unless covered by pavements or slabs, the passive resistance in the upper 12 inches of soil should be neglected. 5.2.2 Perimeter Footing Drains Footing drains should be installed around the perimeter of the building, at or just below the invert of the footings. Under no circumstances should roof downspout drain lines be con- nected to the footing drain systems. Roof downspouts must be separately tightlined to appropriate discharge locations. Cleanouts should be installed at strategic locations to allow for periodic maintenance of the footing drain and downspout tightline systems. 5.2.3 Footing Subgrade Preparation Our test borings encountered 3 to 4V2 feet of fill below the site. The fill is loose and would not be suitable for direct support of foundation loads. If fill is encountered at the foundation subgrade elevation, the fill should be overexcavated and replaced with structural fill. The overexcavation width should extend at least one half the overexcavation depth beyond the width of the foundation elements. All footing subgrade should be properly prepared and in a dense and unyielding condition prior to setting forms and placing reinforcing steel. Any loose or softened soil should be removed from the footing excavations. The adequacy of the footing subgrade soils should be verified by a representative of PanGEO, prior to placing forms or rebar. 5.3 FLOORS SLABS The floor slabs for the proposed building may be constructed using conventional concrete slab -on -grade floor construction. The floor slab should be supported on competent native 19-049 1515 132nd St SE Page 7 PanGEO, Inc.