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8.0 Groundwater Quality Data <br />Groundwater quality data for hydrogeologic units within the Alluvial, Dakota, Salt <br />Wash and Navajo aquifers is summarized in Table 8-1 based on regional data <br />provided by Weir et al. (1983). Water quality characteristics vary between the <br />hydrogeologic units. General groundwater quality characteristics include the <br />following: <br />¦ Groundwater from alluvial aquifers has moderate to high concentrations of total <br />dissolved solids (TDS), chloride and sulfate with neutral pH; <br />¦ Groundwater from the Dakota aquifer has high concentrations of TDS, chloride and <br />sulfate with neutral pH; <br />¦ Groundwater from the Salt Wash aquifer has moderate concentrations of TDS, <br />chloride and sulfate with neutral pH; and <br />¦ Groundwater from the Navajo Aquifer varies with depth and hydrogeological unit. <br />Groundwater from depths of less than 500 ft. has moderate to high concentrations <br />of TDS, chloride and sulfate, with moderate to slightly alkaline pH. Groundwater <br />from depths greater than 500 ft. has very high concentrations of TDS, sulfate and <br />chloride, and slightly alkaline pH. <br />As described previously, the underground mine workings are not currently accessible <br />and groundwater quality data from the direct vicinity of the Van 4 Mine are not <br />available. <br />8.1 Existing and Potential Future Uses of Groundwater <br />Existing or potential future uses of groundwater in the vicinity of the Van 4 Mine are <br />limited because most of the surrounding land is public land administered by BLM. <br />Groundwater use in the direct vicinity of the Van 4 Mine area is not occurring, and <br />the primary future use of groundwater in the area is likely for industrial uses to <br />support underground mining operations. In the area of Fawn Springs, located <br />approximately 1.5 miles downgradient of the mine, groundwater uses may also <br />include occasional livestock or wildlife uses. <br />Exhibit 8-1 shows existing wells in the area of the Van 4 Mine. These wells are all <br />related to other uranium mining activities in the area and include one well permitted <br />for industrial use and five monitoring wells. Most of these wells are located in an area <br />of extensive previous uranium mining located approximately 2 miles north of the Van <br />4 Mine. This mining area is located on the slope break between Monogram Mesa and <br />Paradox Valley to the north. It is unlikely that these wells would be affected by <br />Denison activities, because of the distance from the Van 4 Mine site. One of the <br />existing monitoring wells is located on Monogram Mesa approximately 1.3 miles west <br />of the Van 4 Mine. This well is permitted by Cotter Corporation, another uranium <br />mining company. This well is unlikely to be affected by the Denison activities because <br />it is located west of a tributary to Bull Canyon. Groundwater flow on both sides of the <br />tributary is likely towards the south into Bull Canyon based on the orientation of the <br />8-1 <br />T:\64986-Denison Mines\Task Order 4- EPP Sunday Mines Group-Van4\Van4\FINAL Report\FINAL - Environmental Protection Plan Van4.doc