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If the owner is proposing to build close to the existing slopes (subject to approval by AGS), and if <br />the owner wants added safety factor for foundation stability, then we recommend the use of driven <br />steel pipe piles or straight -shaft drilled piers. <br />Driven Steel Pipe Piles: This type of deep foundation is widely used in the State of Washington <br />for residential construction due to light loading, availability of specialty contractors, and the ease <br />of construction. We recommend the use of steel pipe piles with the following driving and design <br />capacity criteria. These piles should not be used for lateral loading capacity unless the project <br />structural engineer and AGS review and discuss project characteristics together. AGS will modify <br />design recommendations as necessary to provide lateral capacity, once the project plans are <br />finalized and made available for our review. <br />• Pile Diameter and Type: 4-inch diameter, SCH 40, Grade A, galvanized. Black pipe may be <br />used if soil corrosion testing is performed and soils are confirmed as non -corrosive. <br />• Maximum Pile Spacing: Minimum 12 inches for pile group and maximum 5 feet. <br />• Critical locations: Install piles at all building corners, individual columns, and all other stress <br />points. <br />• Minimum Pile Length: 10 feet below the bottom of footing; Minimum 5 feet embedment into <br />onsite clays. Pile lengths can be modified after review of site grading plans and during pile <br />inspections in the field. Actual pile lengths may vary. <br />• Footing Embedment: At least 3 inches of a pin pile should be embedded into the footing base. <br />Additional embedment is recommended for post or pier foundations and for lateral stability of <br />the concrete foundation element. <br />• Pile driving / refusal criteria and Pile Capacity: See table below. Refusal criteria may be <br />revised in the field by AGS representative. <br />Hammer Size <br />(Pound) <br />Pipe Refusal Criteria <br />(sec/inch) <br />Allowable Compression <br />Capacity (kips) <br />650 <br />20 <br />12 <br />800 <br />15 <br />12 <br />1100 <br />10 <br />12 <br />Proposed Construction <br />Project No: 0470-WA18 <br />January 24, 2019 <br />Page No: 7 of 17 <br />