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603284-001 <br />The sample tested for water-soluble chloride content indicates a low <br />potential for corrosion of steel in concrete due to the chloride content of <br />the soil. <br />5.2 Shallow Foundations <br />Spread footings may be established in engineered fill or undisturbed <br />natural soils. <br />5.2.1 Minimum Embedment and Width <br />Footings should have a minimum embedment of 18 inches and have a <br />minimum width of 18 inches. <br />5.2.2 Bearing Value <br />Footings established on engineered fill or undisturbed natural soils may be <br />designed to impose an average bearing pressure of 3,000 pounds per <br />square foot (psf). A one third increase in the bearing value for short <br />duration loading, such as wind or seismic forces may be used. <br />The ultimate bearing capacity can be taken as 9,000 psf. This value does <br />not incorporate a factor of safety and may only be used for an ultimate <br />bearing capacity check with appropriate factored loads. <br />A one-third increase in the allowable bearing may be used for wind or <br />seismic loading. The recommended bearing value is a net value, and the <br />weight of concrete in the footings can be taken as 50 pounds per cubic <br />foot (pcf); the weight of soil backfill can be neglected when determining <br />the downward loads. <br />5.2.3 Settlement <br />The estimated total settlement of the structures supported on spread <br />footings as recommended above is less than M inch. The differential <br />settlement between adjacent columns is estimated to be less than 1/1 inch <br />over a horizontal distance of 30 feet. <br />-22- <br />Leighton <br />SL Rvcd 2019.01.21