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7.0 Groundwater Information <br />• The following sections provide information regarding the local hydrogeologic <br />framework. Additional information regarding regional geology and hydrogeology is <br />discussed in Hydrogeologic Evaluation of the Van 4 Mine (CDM 2009b), included as <br />Attachment H. <br />7.1 Potential Aquifers in Area of Van 4 Mine <br />The hydrogeologic units present in the area of the Van 4 Mine are summarized in <br />Exhibit 7-1, which is based on information regarding the local geological framework <br />and hydrogeologic information provided by Weir et al., 1983. The local geological <br />framework is summarized on Figures 7-1. <br />Exhibit 7-1. Local Hydrogeologic Units in Vicinity of the Van 4 Mine <br />C <br />Hydrogeological Unit Local Description <br />Defined by Weir et al. Hydrologic <br />(1983) Unit <br />Mesozoic Aquifer Navajo Aquifer Aquifer contains saturated portions of the Cutler <br /> Formation, Chinle Formation, Wingate Sandstone, <br /> Kayenta Formation, Navajo Sandstone, and Entrada <br /> Sandstone. The aquifer is overlain by shale of the <br /> Summerville Formation, and underlain by rock salt of <br /> the Paradox Member of the Hermosa Formation. <br /> Salt Wash Aquifer includes the saturated portions of the Saltwash <br /> Aquifer Member of the Morrison Formation. This aquifer is <br /> overlain by bentonitic shales of the Brushy Basin <br /> Member of the Morrison Formation and is underlain by <br /> shale of the Summerville Formation. <br />Tertiary to Upper Dakota Aquifer Aquifer contains the saturated portion of the Dakota <br />Cretaceous aquifer Sandstone and the Burro Canyon Formation. It is <br /> overlain by the Mancos Shale and underlain by shale of <br /> the Brushy Basin member of the Morrison Formation. <br /> Mesaverde Not present in the vicinity of the Van 4 Mine. <br /> Aquifer <br />An aquifer includes only the saturated portion of the respective geological units. Mr. <br />Jon Showalter (Denison Project Geologist, personal communication 2008) reports that <br />a small amount of seepage is present at the base of the Burro Canyon Formation in the <br />area of the Van 4 Mine. Where saturated, the Burro Canyon Formation is a part of the <br />Dakota Aquifer. Cater (1954) does not indicate the presence of springs at the base of <br />the Burro Canyon Formation; however, springs may be present at this contact on a <br />local or seasonal basis that were not identified by Cater (1954). The available data <br />suggest that saturated conditions may be present on a local or seasonal basis at the <br />base of the Burro Canyon Member, but that groundwater within this unit is relatively <br />limited. <br />7-1 <br />T:\64888-Denison Mines\Task Order 4 - EPP Sunday Mines Group-Van4\Van4\FINAL ReporITINAL - Environmental Protection Plan Van4.doc