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Page 6 <br />LEROY CRANDALL <br />AND ASSOCIATES <br />soils should extend at least five feet beyond the building in plan and should <br />also extend beneath any adjacent walks or slabs. Within areas to be paved, <br />the natural soils should be excavated to a depth of at least one foot below <br />the existing grade. <br />After excavating as recommended, the exposed soils should be care- <br />fully inspected to verify the removal of·all unsuitable deposits. Next, the <br />moisture content of the exposed clay soils should be determined. At the pres- <br />ent time, the upper natural soils are generally wet and some drying may be <br />necessary to achieve proper compaction. (If grading is done during the rainy <br />season, drying may be difficult to accomplish and special techniques such as <br />the addition of hyd rated lime may be desirable.) However, the natural clay <br />soils should not be allowed to dry out to.a moisture content less than 3% <br />above optimum moisture content.If necessary, the exposed clay soils should <br />be slowly and uniformly moistened to bring the moisture content to at least 3% <br />above optimum moisture content at a depth of six inches below the excavated <br />surface. The moisture content of the subgrade should be checked and approved <br />prior to placing the required fill. <br />After drying or premoistening if necessary, the surface soils should <br />be rolled with heavy compacti·on equipment. The upper six inches of natural <br />soils should be compacted to 90% of the maximum density obtainable by the <br />ASTM Designation D1557-70 method of compaction modified to use three layers <br />instead of five. · <br />After compacting the natural soils, the required fill should be placed <br />in loose lifts not more than eight inches in thickness and compacted to at least