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Adapt Engineering <br /> foundation embedded more than 1 foot below finished exterior subgrade elevation. These lateral <br /> resistance values incorporate a minimum safety factor of 1.5. <br /> Grading and Capping: Final site grades should slope downward away from the structure so that runoff <br /> water will flow by gravity to suitable collection points,rather than ponding near the structure. Ideally,the <br /> area surrounding the structure would be capped with concrete, asphalt, or compacted, low-permeability <br /> (silty)soils to reduce surface-water infiltration into the subsoils adjacent to/below the foundation. <br /> Settlements: We estimate that total post-construction settlements of properly designed thickened-edge <br /> footings bearing on properly prepared subgrades will be less than 1 inch, with differential settlements <br /> approaching one-half of the total. For a structural slab-on-grade equipment pad with a uniform thickness <br /> (without thickened edges),somewhat greater movements may be experienced. <br /> Tower Drilled Pier Foundations <br /> The subsurface soil and groundwater conditions observed in our site exploration are also considered to be <br /> generally suitable for the use of a drilled pier foundation to support the proposed tower. The following <br /> recommendations and comments are provided for purposes of drilled pier design and construction. <br /> End Bearing Capacities: We recommend that the drilled pier be founded below approximately 15 feet <br /> below the ground surface. For vertical compressive soil bearing capacity, we recommend using the unit <br /> end bearing capacity presented in Table 1 below,where B is the diameter of the pier in feet and D is the <br /> depth into the bearing layer in feet, in accordance with the EIA/TIA G-code. This ultimate end bearing <br /> capacity does not include a safety factor. <br /> Table 1 <br /> Ultimate End Bearing Capacity <br /> Depth(feet) Ultimate Bearing Capacity(tsf) Limiting Point Resistance(tsf) <br /> 15-25 5 D/B 5 <br /> Frictional Capacities: For frictional resistance along the shaft of the drilled piers, acting both downward <br /> and in uplift,we recommend using the ultimate skin friction value listed in Table 2.We recommend that <br /> frictional resistance be neglected in the uppermost 2 feet below the ground surface. The ultimate skin <br /> friction values presented do not include a safety factor,in accordance with the provisions of the EIA/TIA <br /> 222-G code. <br /> AT&T Mobility do General Dynamics October 10,2016 <br /> Adapt Project No.WA16-20654-GEO <br />