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Response to DRMS Comments Enu/ronmentatProtection P/an, <br />Denison SundayMhes Group <br />Response to Technical Adequacy Comments <br />Sunday Mines Group Environmental <br />Protection Plan <br />This document provides responses to technical adequacy comments from the Colorado <br />Division of Reclamation and Mine Safety (DRMS), dated February 17, 2010, on the <br />Environmental Protection Plan (EPP) for the Denison USA Corp. (Denison) Sunday <br />Mines Group, West Sunday (M-1981-021, amendment A-1), Topaz Mine (M-1980-055 <br />HR, Amendment AM-1), Sunday Mine (M-1977-285, Amendment AM-3), Carnation <br />Mine (Permit M-1977-416 HR, Amendment AM-1), and the St Jude Mine (M-1978-039 <br />HR, Amendment AM-1), dated December 2010. These mines are located in San Miguel <br />County, Colorado and are collectively referred to as the Sunday Mines Group. <br />Comments provided by DRMS have been reproduced and presented in italic print. <br />CDM's responses are provided in standard font. <br />Comments provided by Mr. Bob Oswald, DRMS, dated <br />February 17, 2010 <br />General Comments <br />Comment 1 OrePadLirter. As shown by UNSAT-H modeling, the potential for percolation <br />of water to groundwater resources from the waste rock and ore stockpiles does <br />exist though it the model indicates that it may be minimal. As such, the <br />requirement for lined ore pads is justified. <br />Response Acknowledged. <br />Comment 2 OreFadSize. The site maps depict acceptable liner locations. All are shown to <br />be 100 ft x 100 ft, a standard size which comports with the written description. <br />The exception is at the St. Jude Mine, as depicted in Figure 2-2, which shows a <br />50 ft x 200 ft liner. This does not match the 50 x 100 ft description included in the <br />narrative. Please clarify. <br />Response During the ore pad design for each of the mines, existing surface features, <br />required operations, and ore production rates were evaluated to locate <br />and size the ore pads. The ore pad design (see Attachment S - Ore <br />Storage Pad Drawings and Specifications) provides information on the <br />ore pad locations and dimensions. In addition, EPP replacement pages <br />and figures are provided to consistently present the ore pad locations and <br />dimensions. <br />Comment 3 Ore Pad Geotexlileflaterial. The Division and Denison agree that due to the <br />inherent limitations of the onsite soil for use as a soil liner, an impermeable geo- <br />membrane is required. Denison has proposed using a 30-mil PVC liner, but the <br /> <br />Final Sunday Mines RTC_v2.doc