Laserfiche WebLink
15. Addressing Rule 6.4.21(1 l)(a), please address this rule. The Division considers the San <br />Miguel River to be a receiving stream within two miles and down gradient from the <br />affected land <br />While there are no diversions immediately downstream of SM -18, water is used <br />for irrigation and eventually municipal water supply sources within the <br />Colorado River basin. Direct discharge of surface water runoff would be <br />expected to meet federal drinking water standards. While the San Miguel River <br />is within two miles of SM -18, hydraulic and geochemical conditions presented in <br />the application clearly show that the river is not down gradient of the mine <br />workings and the potential for uranium related constituents reaching the river is <br />minimal. Monitoring of lysimeter data and drill data strongly suggest that if <br />groundwater exists at the site it occurs as perched water zones of limited extent. <br />Without extensive groundwater in the area, there is no pathway for the <br />migration of uranium related constituents. The dip of the Salt Wash Member of <br />the Morrison Formation is to the northeast, away from the river, and <br />groundwater, if present, would flow along the dip of the rock (refer to Figure <br />U3). Groundwater flow velocities in the Salt Wash Member of the Morrison <br />Formation are estimated to be less than a foot per year. Geochemical <br />conditions, as discussed in the EPP, also limit the rate of migration. <br />16. Addressing Rule 6.4.21(12), on page U -16, the EPP states that "Water encountered <br />during mining will be sampled and sent for chemical analysis. If levels of uranium- <br />related constituents are above regulatory guidelines, Cotter will initiate monitoring <br />according to DRMS regulation. A well will be placed down gradient of the mining area." <br />If groundwater is encountered during mining, a minimum of three monitoring wells shall <br />be installed an up gradient well, a down gradient well and a point of compliance well. <br />The location of the point of compliance must be approved by the Division prior to <br />installation. Also, subject to Division approval, a sampling and analysis plan shall be <br />implemented in accordance with Rule 6.4.21(12) and Rule 3.1. regardless of the results <br />of the chemical analysis. <br />6 <br />