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If the proposed loads exceed these values,the proposed grades differ by more than 2 feet from the assumed values or if the design or location of the proposed building changes,we should be informed. Additional analyses and revised recommendations may be necessary. 4.2 Discussion The soil borings completed for this project encountered about 4 feet of fill soils. The existing fill soils are not suitable for foundation support and will need to be removed and replaced with suitable compacted engineered fill. The underlying native clay till soils appear directly suitable for foundation support. Groundwater was not encountered in either boring while drilling and sampling or after removing the augers from the boreholes. It appears that groundwater levels were below the depths explored by our borings. We recommend the lowest floor grades of the new building be constructed to maintain at least a 2-foot separation between the lowest floor slab and 100 year flood levels of storm water ponds or other nearby surface water features. 4.3 Building Pad Preparation Excavation We recommend that all vegetation, topsoil, fill soils and soft clays be removed from the proposed building and oversize area. Table 1 below summarizes the anticipated excavation depths at the boring locations. Excavation depths may vary and could be deeper. Table 2. Anti ci ated Excavation Depths BoringMeasured Anticipated Anticipated Surface Excavation Excavation Number Elevation feet Depth(feet)* Elevation(feet)* SB-1 961.1 4 957 SB-2 J 963.1 4 959 *=Excavation elevations were rounded to nearest 1/2 foot Oversizing If the excavation extends below the proposed footing elevation, the excavation requires oversizing. We recommend the perimeter of the excavation be extended a foot outside the proposed footprint for every foot below footing grade (1H:1V oversizing). The purpose of the oversizing is to provide lateral support of the foundation Backfilling We recommend sands be used for engineered fill to provide a less frost susceptible subgrade and for ease in compaction. We recommend that backfill placed to attain site grades be compacted to a minimum of 95 percent of its standard Proctor density (ASTM D 698). Granular fill classified as SP or SP-SM (with less than 12% passing the #200 sieve) should be placed within 65 percent to 105 percent of its optimum moisture content as determined by the standard Proctor. Other fill soils should be placed within 3 percentage points above and 1 percentage point below its optimum moisture content as determined by the standard Proctor. All fill should be placed in thin lifts and be compacted with a large self- propelled vibratory compactor operating in vibratory mode. 4