2920 CHESTNUT ST 2016-01-01 MF Import

David Kehle, Architect W-3574 9 April 1981 Page Three Al1 compacted fill should be placed under the full-time obser•vation of a qualified Soils Engineer. The existing onsite material contains sufficient silt and clay so that com- paction will be difficult or impossible when the soil is more than a few percent above the "optimum moisture" content. Typically, these soils will require drying in order to attain 90% compaction; thus, site preparation work should be scheduled for the driest time of the year. Even then, delays in grading are possible due to inclement weathcr. Should damp or wet weather gradin9 be required, the fill material should consist of a "clean" imported sand and gravel , containing less than 5% fines by weight passing the Number 200 sieve. This percentage is based on the soil fraction which passes the Number 4 sieve. Clean sands and gravels can nor•mally be placed and compacted under a variety of weaY�er conditions. In addition, if the stripped ground sur•face is too moist to recompact, and it cannot be dried, the base of the fill should consist of a clean, coarse, granular soil , capable of creating a capillary break between the subgrade and the fill . III. Foundations When founded 1-1/2 to 2 feet below the original ground surface, conventional spread or continuous footings, may be used for sturctural support of the pro- posed structure. These footings may be designed to support a maximum allowable bearing pressure of 2000 psf including both dead and live loads. An increase of 1/3 may be used for short-term, wind or seismic loadings. All fuotings should have a minimum width of 12 inches. Exterior footings should penetrate eighteen inches below adjacent ground for frost protection. Interior footings need penetrate only 12 inches below the ground floor slab. Footings founded on properly compacted fill may also be designed for a maximum allowable bearing pressure of 2000 psf. The fili material should he placed i i �