2401 TAYLOR DR Geotech Report 2022-10-25

2401 Taylor Drive Geotechnical Engineering Study Everett, Washington circumstances should concentrated discharges be allowed to flow over the steep slope on the north end of the site. 6) Soils that are to be reused around the site should be stored in such a manner as to reduce erosion from the stockpile. Protective measures may include, but are not limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the use of straw bales/silt fences around pile perimeters. During the period between October 1 and March 31, these measures are required. 7) On-site erosion control inspections and turbidity monitoring should be performed in accordance with City of Seattle requirements. Weekly and monthly reporting to Ecology should be performed on a regularly scheduled basis. TESC monitoring should be part of the weekly construction team meetings. Temporary and permanent erosion control and drainage measures should be adjusted and maintained, as necessary, at the time of construction. It is our opinion that with the proper implementation of the TESC plans and by field-adjusting appropriate mitigation elements (best management practices) during construction, as recommended by the erosion control inspector, the potential adverse impacts from erosion hazards on the project can be mitigated. GEOTECHNICAL ENGINEERING RECOMMENDATIONS The medium stiff to hard silt and very dense sand comprising the native Whidbey Formation deposits located below the existing site grade is suitable for the support of spread footing foundations. The following sections provide our recommendations for foundation support and support of slab-on-grade floors. Site Preparation Site preparation of planned structural fill, building pads, and other areas should include removal of all trees, brush, grass, debris, and any other deleterious material. Additionally, all unsuitable fill or weathered soils and the upper organic topsoil should be removed and the remaining roots should be grubbed. Areas where loose surficial soils exist due to grubbing operations should be recompacted in place, or if this is not feasible due to either soil composition or moisture content, the loose soils should be removed and replaced as subsequently recommended for structural fill placement. In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however,we anticipate that temporary, unsupported cut slopes in the native soils may be made vertical for no greater than November 6, 2019 SONDERGARRD GEOSCIENCES, PLLC 6