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Section 13 <br />Geochemical Data and Analysis <br />13.0 Geochemical Data and Analysis <br />Denison has completed extensive geochemical evaluations of ore and development <br />rock during preparation of this EPP. The work plan is presented in the Development <br />Rock, Ore, and Soil Cliaracterization Data Collection Work Plan to Address Designated <br />Mining Operations (DMO) Status Sunday Mines Group and Van 4 (CDM 2008f), which is <br />included as Attachment R. The results of these investigations are presented in the <br />Environmental Geoclwmistnj Investigation of Rock and Soil Material Sunday Group Mines <br />(CDM 2009), which is included in this report as Attachment B. This section provides a <br />summary of the results of the geochemical investigations. <br />13.1 Naturally Occurring Geological and Geochemical <br />Conditions <br />There are two major categories of naturally occurring geochemical conditions that are <br />important in relation to the Sunday Mines Group: <br />1. Naturally occurring high salinity that results from outcrops of the Paradox <br />Member of the Hermosa Formation; and <br />2. Natural enrichments of uranium, vanadium, and other metals, which are <br />associated with the uranium-vanadium ore deposits in the Salt Wash Member <br />of the Morrison Formation. <br />The affected areas of the Sunday Mines Group are located in Big Gypsum Valley, <br />which is formed from a collapsed salt intrusion. The Paradox Member of the Hermosa <br />Formation is dominantly composed of rock salt (halite [NaCl] and sylvite [KCl]) as <br />well as gypsum (Ca(SO4) •2H20). This unit crops out in several areas of lower Big <br />Gypsum Valley, and salt originally present in the rock unit has dissolved and been <br />dispersed in the environment. Enrichments of sodium, potassium, and sulfate are <br />expected in this area as a result of dissolution and geochemical dispersion of rock salt <br />and gypsum. Natural enrichments of other elements such as selenium, which is <br />geochemically associated with sulfate enrichment are also likely in the area. Natural <br />evaporative concentration of sulfate and selenate salts would also be expected in the <br />and environment of Big Gypsum Valley. <br />The Sunday Mines Group is located within the larger Uravan Mineral District, and <br />natural enrichments of uranium, vanadium and other metals are present in the area. <br />Although the Sunday Group deposits are largely sub-surface, outcropping uranium- <br />vanadium mineralization is present in numerous locations within the Big Gypsum <br />Creek watershed (e.g. Cater 1955). Other elements that are associated with naturally <br />occurring uranium-vanadium enrichment include arsenic, molybdenum, selenium, <br />lead, and copper (Rose et a1, 1979). <br /> <br />13-1 <br />T:\64966-Denison Mines\Task Order 4- EPP Sunday Mines GroupTINAL EPPTINAL - Environmental Protection Plan Sunday Mines.doc