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• 2) The Footings or pad sizes should be computed using the above soil pressures and placed oa a <br />minimum of 2 feet of recompacted natural soils found beneath the existing topsoil and organics or <br />on the undisturbed sandstone bedrock. The 2 feet minimum depth of scarified natural soils below <br />the bottom of the footings should be moisture conditioned and placed in 6 to 8 inch lifts. The <br />natural soils should be compacted to at least 100% of the maximum standard Ptoctor density and <br />within 2% of the optimum moisture content determined in accordance with ASTM D-698. <br />3) Any topsoil and organic materials, loose or soft pockets of soil found beneath the scarified <br />materials when the excavations are opened should be removed and the excavations should be <br />extended down to more competent natural soils prior to fill placement. <br />4) The foundation walls should be designed and reinforced to span an unsupported distance of 10 feet <br />or the length between pads, which ever is Beater. <br />5} The footing or pads should be placed well enough below fmal backfill grades to protect them from <br />frost heave. Forty-eight (48) inches is typical for this location considering normal snow cover and <br />other winter factors. <br />6) Based on experience, we estimate total settlement for footings and pads designed and constructed <br />as discussed in this section will be approximately 1 inch. Additional bearing capacity values along <br />• with the associated settlements are presented in Figures #8 and #9. <br />7} We recommend that an engineer from this office be called to the site when the foundation <br />excavations are near complefion to identify the bearing soils and confirm the recommendations in <br />this report. m addition, the processed and recompacted fill materials placed below the foundations <br />should be tested for compaction by this office. <br />Alternate Foundation Recommendations: If the owner is not willing to accept the risks associated with <br />placing the shallow foundations on swelling soils or if the minimum dead load requirement cannot be met, <br />we recommend that the building be placed on a deep foundation system consisting of either straight shaft <br />skin friction/end bearing piers or Helical Screw Piles drilled into the underlying bedrock materials. <br />Foundation movement should be within tolerable limits if the following design and construction precautions <br />for the drilled piers are observed. <br />1) A minimum pier diameter of 12 inches, a minimum bedrock penetration of 5 feet and a minimum <br />pier length of 15 feet are recommended. <br />2) The piers should be designed using an allowable skin friction value of 3,000 psf for the portion of <br />the pier drilled into the undisturbed bedrock materials. [f a drill rig of sufficient size, type and <br />• operating condition is used, and the bottom of the piers can be cleaned out properly, an allowable <br />end bearing pressure of 30,000 psf can be used for the properly cleaned piers drilled into the <br />undisturbed bedrock materials. <br />Job Number: 03-5838 NWCC, Inc. Page 5 <br />