1004 BROADWAY EVCC STUDENT HOUSING - REPORTS & FINAL DOCUMENTS 2017-01-13

Geotcchnical Report - _ __ . scd Proposed Apartinents: 1002, 1006, and 1008 Broadway Street, Everett, Washington May 12, 2015 liquefaction are typically cohesionless, predominately silt and sand sized, must be loose, and be below the groundwater table. The site is predominantly underlain by very dense silty sand with gravel without a defined groundwater table. Based on these conditions, in our opinion the liquefaction potential of the site is negligible and design considerations related to soil lic�uelaction are not necessary for this project. 4.2 Bu��,��Nc FouNnATioNs Based on the subsurface conditions encountered at the site and our understanding of the planned development, it is our opinion the proposed building may be supported on conventional spread and continuous footings. The footings should bear on the dense to very dense, undisturbed native soil underlying the site, or on properly compacted structural fill placed on undisturbed native soil. Exterior foundation elements should be placed at a minimum depth of 18 inches below final exterior grade. Interior spread foundations should be placed at a minimum depth of 12 inches below the to� of concrete slabs. We recoinmend that a maximum allowable soil bearing pressure of 4,000 pounds per square foot (ps� be used for sizing foundation elements bearing on dense to very dense native soil, or on structural fill. PanGEO should be retained to determine the adequacy of footing subgrade during construction. The recommended allowable soil bearing pi-esslu�e is foi• dead plus live loads. For allowable stress design, the recommended bearing pressure inay be increased by one- third for transient loading, such as wind or seismic forces. Continuous and individual spread footings should have minimum widths of 18 and 24 inches, respectively. Footings designed and constructed in accordance with the above recommendations should experience total settlement of less than one inch and differential settlement of less than % inch. Most of the anticipated settlement should occur during construction as dead loads are applied. 4.2.1 Later�cl Resistartce 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. Por footings bearing on the dense io very dense silty sand, a frictional coefficieni of 0.35 may be used to evaluate 15-0=}8 1003 Rroadway. Rcviscd Pc`lbe 6 Pa1lGE�; II�C.