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• optimum moisture values will vary depending on the actual gradation and material <br />properties that are produced by the processing plant and will need to be checked <br />and revised during initial construction. <br />To summarize, the coal waste should be placed in lifts and compacted to at <br />~~ least 90 percent of maximum dry density per AASHTO T 99-74. Lift thickness should <br />I~\\~ be 24 inches, or greater if adequate compaction wfth the available equipment can be <br />G <br />~ ~~ ~ verified from field testing. The initial estimate of moisture content required to achieve <br />UN~S~S~a`~~1~1,1~1,~r`~-compaction, and not generate excess water within the fill, ranges from 5 percent <br />nN1 below optimum moisture to 3 percent above optimum. Testing should be performed <br />~ " Y~~ either every other lift (maximum 4 feet between tests), or 3 months after the last test, <br />~v~ whichever is shorter. <br />• Inspection and Testing <br />We recommend the following items be inspected by a qualified engineer: <br />1. Intial stripping and excavation of cover material. <br />i 2. Initial excavation of the toe buttress to confirm foundation conditions <br />are as anticipated. <br />3. Initial drain construction to evaluate construction procedures. <br />Samples of drain rock and filter material should be tested prior to use. <br />i Drain rock should be tested for durabilRy and gradation. The filter <br />material should be tested for gradation. <br />4. The initial product of the processing plant should be evaluated to <br />confirm the properties used in the design. Gradation, Proctor, <br />i moisture content and strength (direct shear) testing should be <br />(~\~Q performed. <br />5. Initial RDA construction should be observed and density tested to <br />evaluate compaction procedures and material properties after handling <br />and compaction. <br /> <br />n <br />U <br />24 <br />i <br />