3620 36TH PL NE 2018-01-02 MF Import

4.4.2 Allowable Bearing Pressure Footings may be designed using an allowable soil bearing value of 2,500 poun& per square foot (psO provided they are founded on at least 2-feet of properly compacted structural fill. The allowable soil bearing values apply to the total of dead and long-term live loads and may be increased by up to one-third for wind or seismic loads. We recommend that the spread footings be founded a minimum of 18 inches below the lowest adjacent grade. Perimeter or strip footings should have a minimum width of 24 inches. 4.4.3 Settlement Provided the footings are supported on at least 2 feet of properly compacted structural fill that has been preloaded, we estimate the post construction total settlement of shallow foundations will range up to 1 inch. The majority of the settlement will occur rapidly, within four to five weeks after application of loads. Differential settlements along a 25-foot section of continuous wall footing should be less than / inch. We expect most of the footing settlements will occur as loads are applied. Loose or disturbed soils, and old fill or wood debris not removed from the footing excavation prior to placing concrete will result in additional settlement. We recommend that the footing excavations be cut using a smooth edged bucket to reduce the amount of disturbed soil exposed at the subgrade. Immediately prior to placing concrete, all debris and soil slough that accumulated in the footings during forming and steel placement must be removed. Debris or loose soils not removed from the footing excavations will result in increased settlement. 4.4.4 Lateral Resistance Lateral foundation loads may be resisted by passive resistance on the sides of footings and by friction on the base of the footings. For footings supported on structural fill placed and compacted in accordance with our recommendations, the allowable frictional resistance may be computed using a coefficient of friction of 0.35 applied to vertical dead -load forces. The allowable passive resistance may be computed using an equivalent fluid density of 300 pcf (triangular distribution). The structural fill should extend out from the face of the foundation element for a distance at least equal to three times the depth of the element. The above coefficient of friction and passive equivalent fluid density values incorporate a factor of safety of about I.S. 4.4.5 Footing Drains We recommend that perimeter footing drains be installed around the office building. The perimeter drains should be installed at the base of the exterior footings. The perimeter drains should be provided with cleanouts and should consist of at least 4-inch-diameter perforated pipe placed on a 3-inch bed of, and surrounded by, 6 inches of drainage material enclosed in a non woven geotextile fabric such as Mirafi 140N (or approved equivalent) to prevent fine soil from migrating into the drain material. We recommend that the drainpipe consist of either heavy -wall solid pipe (SDR-35 PVC, or equal) or rigid corrugated smooth interior polyethylene pipe (ADS N-12, or equal). We recommend against using flexible tubing for footing drainpipes. The drainage material should consist of pea gravel or "Gravel 9 G e 0 E n g i n e e r s 17 File No. 10625-001-02/123003