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6.0 Evaluation of Proposed and Existing Environmental <br />Protection Facilities <br />An environmental protection facility (EPF) is defined by HRMMR §1.1(15) as follows: <br />"Environmental Protection Facilihf" means a structure zvhich is identified in <br />the "Environmental Protection Plan" as designed, constructed, and operated <br />for control and containment of designated chemicals, acid mine drainage, or <br />toxic or acid-forming materials that will be exposed or disturbed as a result of <br />mining and reclamation operations." <br />Although geochemical assessment of ore has indicated that the material is not toxic <br />forming from a risk management criteria (RMC) perspective, as a best management <br />practice, Denison has designated an ore storage pad as an EPF for the Van 4 Mine. <br />Production and storage of ore is not currently being conducted at the Van 4 Mine. <br />Prior to resuming these operations, Denison will construct ore pads that are compliant <br />with DRMS' "General Ore Pad Construction Criteria." Denison is committed to <br />providing containment of surface water in contact with ore material. The conceptual <br />design for the ore storage pad, including the use of a geomembrane liner, is provided <br />below. Denison will submit a complete ore storage pad design (e.g., specifications and <br />drawings) to DRMS for review and approval prior to construction of this EPF. <br />6.1 Proposed Ore Storage Pad with Geomembrane Liner <br />Ore is temporarily stored at a stockpile location at the Van 4 Mine and is routinely <br />transported by truck to the White Mesa Mill near Blanding, Utah for processing (ore is <br />typically stored for relatively short time periods of one to two weeks; less than 180 <br />days). An ore storage pad will be constructed at the stockpile area to contain surface <br />water during future ore storage/ stockpiling activities. <br />6.1.1 Proposed Conceptual Design <br />The existing ore stockpile area will be replaced with a 100-ft by 100-ft ore storage pad. <br />On site soils do not meet the minimum requirements of plasticity (plasticity index of <br />10 percent) for use as soil liner material. Accordingly, Denison proposes to use a <br />polyvinyl chloride (PVC) geomembrane liner for ore pad construction. The conceptual <br />pad layout is shown in Figure 2-1. Soil from the footprint of the ore storage pad will <br />be used to construct a three-foot high berm along the perimeter of the pad and may <br />also be used as liner backfill. The berm will be constructed to contain surface water <br />run-off from the pad area. The geomembrane liner will be installed consistent with <br />the manufacturer's specifications and an anchor trench will be constructed to secure <br />the liner. Select material, typically with grain size no larger than 0.5-inch in diameter, <br />will be used as bedding and backfill to prevent puncture damage to the membrane <br />from the use of heavy equipment on the pad. <br />Additional conceptual design information, including recommended liner <br />manufacturer's, design guidelines, and installation procedures for the PVC <br />geomembrane liner system at the Van 4 Mine, is provided in Attachment K. <br />Supplemental design and installation guidelines and material specifications for a 30 <br />mil PVC geomembrane liner from Colorado Lining International are also provided <br />6-1 <br />7164986-Denison Mines\Task Order 4 - EPP Sunday Mines Group-Van4\Van4\DRMS RTC and Revised EPP\FINAL DRMS Repod - EPP Van4.doc