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Inwood 10 LLC <br />Project B14-08413 <br />December 3, 2014 <br />Page 11 <br />occur. Grading to direct surface drainage away from buildings helps limit the potential for saturation and <br />subsequent heaving to occur. Still, even limited amounts of movement can create tripping hazards to <br />building employees and guests. One way to help limit the potential for heaving to occur is to remove <br />frost-susceptible soils present below the overlying slab “footprints” down to bottom-of-footing grades, <br />and replace them with non-frost-susceptible (NFS) backfill consisting of medium to coarse grained sands <br />having less than 5 percent of the particles by weight passing a #200 sieve. We recommend differential <br />frost heave should be accommodated at transition areas. <br />D.5.Utilities <br />Based on the borings, we anticipate the soils at typical invert elevations should be suitable for utility <br />support. However, if unfavorable conditions such as soft clay, organic soils or perched water are <br />encountered at invert grades, the unsuitable soils may require some additional subcutting and <br />replacement with sand or crushed rock to prepare a proper subgrade for pipe support. Utilities should <br />not be placed within the 1:1 oversizing of foundations. If it is necessary to place utilities within the <br />oversizing of the footings, we should review the documents prior to construction as it may be necessary <br />to backfill with lean concrete or lower the footing elevations near the utility trenches. We anticipate <br />utilities can be installed per manufacturer bedding requirements. <br />A majority of the soil borings indicated the site predominantly consists of sandy soils. These soils are <br />considered non- to only slightly corrosive to metallic conduits. If utilities extend through clay soils, the <br />utilities should be bedded in sandy soil free of any clay lumps or the utilities should be constructed with <br />non-corrosive materials. <br />D.6.Pavements <br />D.6.a.Subgrade Preparation <br />We recommend the vegetation and topsoil be removed from the upper 3 feet below the pavement <br />section. In areas requiring engineered fill to establish pavement grades, the excavation should be <br />oversized at least 1 foot beyond the outside edge of the paved areas for each foot of fill placed below the <br />roads or parking lot. <br />Prior to the placement of engineered fill or pavements, we recommend the exposed sandy soils in the <br />bottoms of the excavations be thoroughly compacted by a minimum of 5 passes with a large (3-foot- <br />diameter drum minimum), self-propelled drum compactor. This is recommended to further densify the <br />underlying native soils and to provide a more uniform base to place additional fill or pavement.