1111 80TH ST SW BLDG SHELL 2016-01-01 MF Import

Cornerstone Columbia Development Co. W-6984 5 July 1990 Page 7 deposits would provide a suitable foundation support for the proposed development. Prior to footing construction, the site should be prepared by stripping, prerolling and/or structural fill placement as outlined earlier. The following preliminary foundation design recommendations are presented for planning of the anticipated development. These are considered appropriate for typical low-rise office construction of moderate structural loading. When final development plans are developed, we recommend that our firm be consulted to confirm or modify these recommendations, as appropriate for the structure types, loading, settlement sensitivity, and grades. An allowable soil bearing pressure of 2500 pounds per square foot (psf) may be utilized for design of shallow footings founded in medium dense natural soils or properly compacted structural fill. Alternatively, an allowable soil bearing pressure of 4000 psf may be utilized for footings supported directly upon the dense glacial till. No footings should be founded in or above any top soil, undocumented fill, or loose native soils. These allowable bearing pressures may be increased by up to 1/3 to accommodate transient or seismic loads. For frost protection, the base of exterior footings should be located a minimum depth of 18 inches below adjacent grade or top of floor slab, whichever is lower. Interior footings need only penetrate 12 inches below surrounding ground or slab level. We recommend that all footings have a minimum width of 18 inches. If the footings are constructed above structural fill, the structural fill pad should extend laterally outside the edges of the foundation, a distance equal to the thickness of the structural fill layer beneath the footing. Foundation settlements will be closely related to the quality of the earthwork performed on the site. Assuming moderate loading, we estimate that total settlement of the foundation elements placed on the properly prepared native soils or structural fill should not exceed 3/4 inch, with differential settlements of approximately '/Z-inch or less. However, it should be noted that actual settlements could increase if care is not exercised during fill placement and/or foundation construction. We recommend that footing excavations be observed prior to placement of concrete by a representative from our firm to observe that the bearing soils are undisturbed and consistent with the recommendations within this report.