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I �� �' �'� <br /> Geotechnical Engineering Report SSGC <br /> Hardeson Road Retail <br /> I Everett,Washington <br /> SSGC Project No. 18072 <br /> September 18,2018 <br /> IGEOTECHNICAL DESIGN CONSIDERATIONS <br /> IThe planned development is considered feasible based on observed soil conditions in the test pits. <br /> However, substantial thicknesses of unsuitable fill materials are present on the site. Although we are <br /> unaware of planned finish grades for the proposed development, removal of substantial amounts of fill is <br /> anticipated to lower grades for access. The amount of planned fill removal will influence final design and <br /> construction. As the fill is variable in type and consistency, it is not considered suitable for direct support <br /> I of foundations or slabs. Native soils or new engineered structural fill over native soils should be used for <br /> support of conventional spread footing foundations and slab-on-grade floors. Some of the existing fill. <br /> could potentially be left in parking areas depending on final grades. <br /> INative soils generally consist of dense glacial till which will limit infiltration for stormwater control. One <br /> infiltration test completed in the southeastern portion of the site suggests very limited infiltration may be <br /> I feasible in the upper native soils. However, groundwater movement in these soils is considered lateral <br /> and will limit the type of feasible infiltration system. <br /> IRecommendations presented in the following sections should be considered general and may require <br /> modifications when final grades have been established and earthwork and grading occur. As final grades <br /> I are unknown at this time, final recommendations may differ from those in this report. Subsurface <br /> conditions across the site may vary from those depicted on the exploration logs and can change with time. <br /> Therefore, proper site preparation will depend upon the weather and soil conditions encountered at the <br /> I <br /> time of construction. We recommend SSGC review final plans and assess subgrade conditions at the time <br /> of construction. <br /> IGeneral Site Preparation <br /> Site grading and earthwork should include procedures to control surface water runoff. Grading the site <br /> I <br /> without adequate drainage control measures may negatively impact site soils,resulting in increased export <br /> of impacted soil and import of fill materials, thereby potentially increasing the cost of the earthwork and <br /> subgrade preparation phases of the project. <br /> I Site gradingshould include removal (stripping) of all fill in the buildingarea. Buildingsubgrades should <br /> ( pP g) b'r' <br /> consist of firm native soils following stripping. Fill in pavement areas should be stripped to a depth of at <br /> Ileast one foot below planned finish grades. Final stripping depths can only be determined at the time of <br /> construction. <br /> IGeneral Subgrade Preparation <br /> We recommend exposed subgrades in building and conventional pavement areas are proofrolled using a <br /> I large roller, loaded dump truck, or other mechanical equipment to assess subgrade conditions following <br /> stripping. Proofi-olling efforts should result in the upper .1 foot of subgrade soils achieving a compaction <br /> I level of at least 95 percent of the maximum dry density(MDD) per the ASTM D1557 test method. Wet, <br /> loose, or soft subgrades that cannot achieve this compaction level should be removed (over-excavated) <br /> I <br />