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Adapt Engineering <br /> Frozen Subgrades: If earthwork takes place during freezing conditions,we recommend that all exposed <br /> subgrades be allowed to thaw and be recompacted prior to placing foundations or subsequent lifts of <br /> structural fill. <br /> Equipment Foundations <br /> It is our understanding that support for the proposed equipment cabinet pad will consist of a <br /> poured-in-place, concrete slab-on-grade with thickened edges; we recommend that these thickened slab <br /> edges be designed as spread footings. Alternatively, the equipment support pad may be designed as a <br /> structural slab-on-grade with a uniform thickness and a reduced bearing pressure. In either case, we <br /> anticipate that the support pad bearing pressure will be relatively light.The following sections provide our <br /> recommendations and comments for equipment pad design and construction. <br /> Subgrade Conditions: The prepared bearing subgrade soils should consist of firm and unyielding,native, <br /> silty sand. Exposed slab-on-grade, footing or overexcavation subgrades should be compacted to a firm, <br /> unyielding state,in accordance with the recommendations provided in the Site Preparation section of this <br /> report. <br /> Sub grade Verification: Footings or slabs-on-grade should never be cast atop soft, loose, organic, or <br /> frozen soils; nor atop subgrades covered by standing water. A representative from Adapt should be <br /> retained to observe the condition of footing subgrades before concrete is poured to verify that they have <br /> been adequately prepared. <br /> Bearing Subgrades: The proposed shallow spread footing system is expected to be founded on the very <br /> loose, poorly graded sand encountered in B-1. Before concrete is placed, any localized zones of loose <br /> soils encountered in the footing subgrades should be compacted to a firm, unyielding condition, if <br /> warranted by soil moisture conditions. Any uncontrolled fill material containing a significant amount of <br /> organic or debris/deleterious materials within the equipment foundation footprint area will need to be <br /> overexcavated and replaced with structural fill,as previously discussed. <br /> Footing Dimensions: For a poured-in-place, concrete slab-on-grade with thickened-edge footings, we <br /> recommend that the spread footing elements be constructed to have a minimum width of 12 inches. For <br /> frost protection, we recommend that the footings exposed to frost at this site penetrate at least 18 inches <br /> below the lowest adjacent exterior grades,or deeper,according to local jurisdictional code. <br /> Bearing Pressure and Lateral Resistance: A maximum allowable static soil bearing pressure of 1,250 <br /> pounds per-square-foot(psf) may be used for thickened-edge pad footings designed as described. For the <br /> alternate equipment support pad design using a uniform thickness, structural slab-on-grade, we <br /> recommend a maximum allowable static soil bearing pressure of 300 psf across the pad area. These <br /> bearing pressure values can be increased by one-third to accommodate transient wind or seismic loads. <br /> An allowable base friction coefficient of 0.35 and an allowable passive earth pressure of 200 pounds per <br /> cubic foot (pcf), expressed as an equivalent fluid unit weight, may be used for that portion of the <br /> AT&T Mobility c/o General Dynamics October 10,2016 <br /> Adapt-Project-No.-WA16-20654=GE0.- <br />