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settlements will result from lower applied loads.The presence of loose or disturbed soils not removed from <br /> footing excavations prior to placing concrete will result in additional settlement. <br /> 4.2.3.Lateral Resistance <br /> Lateral foundation loads may be resisted by passive resistance on the sides of footings and by friction on <br /> the base of the shallow foundations. For shallow foundations supported on native soils or properly <br /> compacted structural fill,the allowable frictional resistance may be computed using a coefficient of friction <br /> of 0.4 applied to vertical dead-load forces. <br /> Passive resistance may be determined using an equivalent fluid density of 300 pounds per cubic foot(pcf), <br /> assuming that the soils against the footings for a distance of twice the footing depth consist of compacted <br /> structural fill. Passive pressure can be increased to an equivalent fluid density of 450 pcf, assuming that <br /> dense to very dense glacial till is present against the foundation. The above coefficient of friction and <br /> passive equivalent fluid density values include a factor of safety of about 1.5. <br /> If soils adjacent to footings are disturbed during construction, the disturbed soils must be recompacted; <br /> otherwise,the lateral passive resistance value must be reduced. <br /> 4.2.4.Foundation Drains <br /> We recommend that perimeter footing drains be installed around the entryways at the base of the <br /> exterior wall footings.The perimeter drains should be provided with cleanouts and should consist of at least <br /> 4-inch-diameter perforated pipe surrounded by 6 inches of drainage material.A non-woven geotextile fabric <br /> such as Mirafi 140N (or approved equivalent)should separate the drainage material from the on-site soils <br /> to prevent fine soil from migrating into the drain material. We recommend that the drainpipe consist of <br /> either heavy-wall solid pipe (SDR-35 polyvinyl chloride [PVC], or equal) or rigid corrugated smooth interior <br /> polyethylene pipe(ADS N-12,or equal).We recommend against using flexible tubing for footing drainpipes. <br /> Figure 3 presents a typical wall drainage and footing drain detail.The perimeter drains should be sloped to <br /> drain by gravity, if practicable,to a suitable discharge point, preferably a storm drain.We recommend that <br /> the cleanouts be covered, and be placed in flush mounted utility boxes.Water collected in roof downspout <br /> lines must not be routed to the footing drain lines. <br /> 4.2.5.Construction Considerations <br /> We recommend that the condition of all footing subgrade areas be observed by GeoEngineers to evaluate <br /> whether the work is completed in accordance with our recommendations and whether the subsurface <br /> conditions are as anticipated. <br /> If soft areas are present at the footing subgrade elevation,the soft areas should be removed and replaced <br /> with structural fill at the direction of GeoEngineers. <br /> 4.3. Floor Slab Support <br /> All slab subgrade areas should be stripped and proofrolled or otherwise evaluated by the geotechnical <br /> engineer before placing any fill.We recommend that the upper 6 inches of fill placed to form the entryway <br /> pads include a capillary break material consisting of 1-inch minus, clean, crushed gravel with negligible <br /> sand or silt, such as Washington State Department of Transportation (WSDOT) Standard Specification <br /> Section 9-03.1(4), American Association of State Highway and Transportation Officials (AASHTO) Grading <br /> GEOENGINEERS� November 14,2019 ; Page 6 <br /> File No.2095-019-07 <br />