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July 3,2017 Single-Family Residence L&A.Job No. 17-079 Page 13 BUILDING SETBACK The purpose of building setback from the top or toe or an overly steep portion of a slope is to establish a safe buffer such that if a slope failure should occur the stability of the structure can be maintained and damages to the structure minimized The steep slope is composed of dense advance outwash soil at shallow depth. To maintain stability of and minimize damage to the proposed residence, we recommend a buffer zone of 10 feet be established from the top of the adjacent steep slope of 40% grade or more. The proposed residence should then be set back at least 5 feet from the buffer zone, Le., 15 feet from top of the steep slope of 40% grade or more, with footing foundations of the proposed residence constructed at least one foot into the dense advance outwash soil. BUILDING FOUNDATIONS Conventional footing foundations may be used to support the proposed residence. The footing foundations should be constructed at least one foot into the underlying, dense advance outwash soil. Water should not be allowed to accumulate in excavated footing trenches. Water should not be allowed in footing trenches. Disturbed soils in footing trenches should be completely removed down to native, undisturbed, advance outwash soil prior to pouring concrete for the footings. If the above recommendations are followed, our recommended design criteria for footing foundations are as follows: • The allowable soil bearing pressure for design of footing foundations, including dead and live loads, should be no greater than 3,000 psf if constructed on or into dense advance outwash soil, and no greater than 2,500 psf if constructed on LIU & ASSOCIATES, INC.