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Project No. JB-569 20 June 2006 Page 7 backfill is not recommended as it may result in an unsatisfactory degree of compaction. 6.1.4 Fill Placement and Compaction After performing the required excavations and/or prior to foundation excavations, the exposed subgrade soil should be carefully inspected to verify removal of all unsuitable deposits. The exposed subgrade soil should then be scarified to a depth of 12 inches, moisture-conditioned, and compacted to a minimum of 90 percent relative compaction at a minimum of 3 percent over optimum moisture content according to the latest ASTM test methods and procedures. After compacting the subgrade soil, all required fill should be placed in loose lifts a maximum of 8 inches in thickness. On-site soil generated by site grading may be used as structural fill provided the soil is free of deleterious and organic materials and is approved for use as fill by our representative. Building Pad backfill should be compacted a minimum of 90 percent relative compaction at a minimum of 3 percent over the optimum moisture content according to the latest ASTM test methods and procedures. General fill and trench backfill should be compacted to a minimum of 90 percent relative compaction at a minimum of 2 percent over the optimum moisture content according to the latest ASTM test methods and procedures. The upper 12 inches of pavement subgrade soils should be scarified, moisture- conditioned as necessary, and recompacted to a minimum of 95 percent relative compaction. If pumping subgrade soils are encountered, we recommend over-excavating to firm, non-yielding soil and placing recompacted fill as recommended in Section 6.1 .4. If non-yielding soil is not encountered within 2 feet below the proposed subgrade elevation, an acceptable option is to place a woven geotextile at the base of the excavation and backfill with a granular material. The geotextile should consist of Mirafi 500X or an approved equivalent. A test area should be prepared to evaluate the performance of the method. If anon-yielding pavement subgrade is not achieved, deeper excavation may be necessary. Soils that are not pumping but are determined to be too wet to properly compact may be prepared by ripping the soil and allowing the soil to dry, excavating and replacing, or lime treating. ~Korbmacher Engineering, Inc.