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The Leadville Mill <br />4.3.1 TSF CONSTRUCTION PREPARATION <br />M 1990 -057 <br />EXHIBIT C — MILL PLAN <br />Page 4 -11 <br />Construction of the TSF impoundment requires the removal and replacement of <br />approximately 95Ost of historic tailings and approximately 5Ost of magnetite, both <br />currently contained within the unlined facility. The TSF overburden stockpile to the <br />east of the existing impoundment will also be removed and incorporated into the <br />fill construction of the lower access road to the concentrate storage, and fill for the <br />impoundment. <br />4.3.2 SUBGRADE PREPARATION <br />Timbering, stump removal, and topsoil removal will occur prior to disturbing <br />additional lands. The timbering and stump removal will be performed by local <br />contractor with the timber removed from the site. The topsoil will be removed in <br />accordance with the topsoil plan and stored in the existing topsoil storage pile. <br />The sub -grade preparation through 45mi1 liner installation for the TSF is as follows: <br />• Clear cut /log trees. Clear and grub organic matter including tree roots, pine <br />needles, dead wood and other deleterious materials. <br />• Clear topsoil and place in topsoil stockpile for reclamation. <br />• Cut and fill to design specifications using contractor selected equipment. <br />Equipment can include track dozer(s), backhoe(s), scraper(s), front end <br />loader(s), road grader(s), sheep foot compactor(s), or excavator(s). <br />• Fill material will have a top size of 6in and contain approximately 50% silt and <br />clay. <br />• Fill will be placed in 10 -12in level lifts and compacted by a self - propelled <br />sheep foot roller. <br />• Fill will be placed and compacted to 95% of Standard Proctor dry density <br />(ASTM D 698). <br />• Fill will be scarified between lifts. <br />• Fill will be moisture conditioned to within 2% of optimum. <br />• Construction engineer will be on site to provide testing during fill placement. <br />• Verify compaction of floor of pond by number of tests recommended by CTL <br />Thompson. <br />• Install Bentomat® DN geosynthetic clay liner or equivalent. <br />Version 1.0 April 2013 <br />