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<br />~ <br />In <br />1'- <br />(~-J <br />c-, <br />(~ <br /> <br />{ <br /> <br />c <br /> <br />22 <br /> <br />For the compacted clay liner, two additional 8 inch lifts of <br />on-site clayey soils should be placed and compacted so as to <br />comprise a liner with a minimum thickness of 18 inches. All of <br />the soils in the liner should consist of clayey soils having <br />greater than 50% fines and should be compacted to at least 98% of <br />the Standard Proctor maximum density at a moisture content close <br />to optimum to minimize shrinkage, maximize density, and minimize <br />permeabili ty. <br /> <br />() <br /> <br />If a synthetic liner is used, it should be placed over smooth <br />bedding material placed on top of the scarified and compacted in <br />situ soils. For exterior dikes, the compacted clay or synthetic <br />membrane liner should extend up the inside face of the dike to <br />include the full width of the dike up to its crest. <br /> <br />The bulk of the dikes can be comprised of compacted random on- <br />site fill. It is likely that most of the random fill will be <br />essentially the same material as will be used for the compacted <br />clay liner since most of the on-site materials are suitable for <br />this purpose. Nevertheless, soils such as pediment materials <br />containing considerable amounts of sand or gravel could also be <br />used for random fill, even though they would not be suitable for <br />compacted clay liner material. The random fill need only be <br />compacted to 95% of the Standard Proctor maximum density at a <br />moisture content ~3% of optimum. <br /> <br />While most of the on-site soils will be suitable for compacted <br />clay liner material, these soils do vary and care will have to be <br />taken to ensure that appropriate materials are placed. This is <br />important when placing pediment soils which locally may have <br />large amounts of coarse-grained material not suitable for use as <br />liner and for weathered Mancos shale which may exist in areas as <br />chips and gravel size material again unsuitable for a liner. It <br />is recommended that full time on-site inspection be maintained <br />during the entire construction period to ensure that only <br />materials of acceptable gradation characteristics are placed for <br />compacted clay liner material. <br /> <br />( <br /> <br />c <br />