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make their own interpretation of the subsurface conditions to determine construction methods, <br />cost, equipment, and work schedule. <br />OPTION I: CONVENTIONAL SHALLOW FOUNDATION <br />The proposed structures can be supported on conventional shallow foundations using the <br />following recommendations: <br />• Over -excavate the footing areas by 24 inches and backfill with compacted granular structural <br />fill. This requirement can be eliminated by performing an open -hole or footing subgrade <br />inspection to make sure expansive soils are not present in the footing areas. <br />• Install adequate perimeter/foundation drains as shown in Figure 8 and discharge into suitable <br />receptacle with proper storm water disposal. Positive drainage away from buildings must be <br />maintained always. <br />• Pour concrete only after all foundation subgrades and foundation drains are inspected and <br />approved by a registered geotechnical engineer from our office. <br />We recommend conventional shallow foundations be designed and constructed in accordance <br />with the following criteria: <br />• Foundations should be designed for a maximum allowable bearing capacity of 2,000 psf <br />(pounds per square foot. For lateral load resistance, passive earth pressure value of 300 pcf <br />equivalent fluid density may be used. A coefficient of friction value of 0.4 (unfactored) may be <br />used for concrete foundation against sandy subgrade. <br />• Estimated final structural loads will dictate the final form and size of foundations to be <br />constructed. However, as a minimum, we recommend bearing walls be supported by <br />continuous footings of at least 24 inches in width. Isolated columns should be supported on <br />pads with minimum dimensions of 36 inches square. <br />• Continuous foundation walls should be reinforced in the top and bottom to further aid in <br />resisting differential movement. See Figure 7. <br />• Exterior footings and footings in unheated areas should extend at least 18 inches below <br />finished exterior grades shallower than 5H:1 V. <br />We estimate total settlement for foundations designed and constructed as discussed in this <br />section will be 1.25 inch or less, with differential settlements on the order of one-half to three - <br />fourths of the total settlement. <br />OPTION II — DEEP FOUNDATION <br />Proposed Construction <br />Project No: 0470-WA18 <br />January 24, 2019 <br />Page No: 6 of 17 <br />