2401 TAYLOR DR Geotech Report 2022-10-25

2401 Taylor Drive Geotechnical Engineering Study Everett, Washington 4 feet high then at a maximum slope of 1H:1V (Horizontal:Vertical). If ground water seepage is observed in the cut,the temporary slopes may need to be readjusted.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 slopes in the native deposits should be no steeper than a 2H:1V inclination. Fill slopes should either be overbuilt and trimmed back to final grade or surface compacted to a specified density. A high percentage of fine-grained material within portions of the on-site soils makes them moisture-sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. Consideration should be given to protecting access and staging areas with an appropriate section of crushed rock or asphalt treated base (ATB). Foundation Support Conventional Spread Footings The foundation bearing stratum should consist of either structure fill over medium stiff to hard native soils or foundations that bear directly upon the native sediments and shallow spread footing may be utilized. Structural fill placed below foundation areas should consist of granular material placed in maximum loose lift thicknesses of 8 inches with each lift compacted to at least 95 percent of the modified Proctor maximum dry density, as determined by American Society for Testing and Materials (ASTM): D 1557. Structural fill placed below footing areas should extend laterally beyond the footing edges a distance equal to or greater than the thickness of the fill. Sediments exposed in footing excavations should be compacted to a firm and unyielding condition prior to footing placement. For footings founded upon structural fill or directly on native soil or structural fill placed over native soil, we recommend that an allowable bearing pressure of 2,000 pounds per square foot (psf) be used for design purposes, including both dead and live loads. An increase of one-third may be used for short-term wind or seismic loading. Perimeter footings for the proposed buildings should be buried a minimum of 18 inches into the surrounding soil for frost protection. No minimum burial depth is required for interior footings; however, all footings must penetrate to the prescribed stratum, and no footings should be founded in or above loose, organic, or existing uncompacted fill soils. November 6,2019 SONDERGARRD GEOSCIENCES, PLLC 7