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Project No. JB-569 20 June 2006 Revised 18 October 2006 Page 8 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. Buttress fill placed within the keyway must be compacted to a minimum of 95 percent relative compaction at a minimum of 3 percent over optimum moisture content. Fill placed above the keyway or above benched areas must be compacted to a minimum of 95 percent relative compaction at a minimum of 1 percent over optimum moisture content. 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 1 2 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. All import fill must be compacted to a minimum relative compaction of 90 percent of the maximum dry density and moisture-conditioned to a minimum of 2 percent over the optimum moisture content according to ASTM test methods and procedures. The import fill should be non-expansive, free of deleterious materials, and meet the requirements in Table 2. Samples of any proposed import fill planned for use on this project should be submitted to our representative for approval and appropriate testing no less than 4 working days before the expected delivery to the job site. K.nrbmacher Engineering, Inc.