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Response to DRMS Adequacy Review — Cotter LP -21 Mine Reclamation Plan Amendment 4. Addressing Rule 6.4.21 (8)(c) — The EPP states, on page U-8, that geological units in the area dip steeply to the northeast. On page U -11, under section 8.3.2, the EPP states that geological formations dip to the northwest. On page U -13, the EPP again states that strata dip to the northwest. Please clarify. The first paragraph on page U -11, under section 8.3.2, should read, "The geologic structure of the area is also important in predicting the direction of groundwater flow. LP -21 is located on the flank of the Paradox anticline with the geologic formations dipping to the northeast at 0.07. Groundwater flow directions in the area are controlled by the dip of the rock and would flow in a similar northeast direction." The second to last paragraph on page U -13 should read, "Assuming saturated conditions existed in the Salt Wash sandstone, a porosity value of 0.2, and a hydraulic gradient of 0.07, equal to the regional dip of the strata, then calculated groundwater transport rates for uranium and related constituents from ore bodies would be approximately less than 4 feet a year in a northeast direction. Average transport rates in the upper -most potential aquifer, assuming that the Wingate Formation contains groundwater, would be less than 100 feet per year in the same northeasterly direction." S. Addressing Rule 6.4.21 (8) — On page U-15, the EPP states that '`numerous boring continued through the ore zone and into the upper portion of the Salt Wash Formation". It has been previously stated that the upper portion of the Salt Wash Member is the ore zone. Please clarify. The borings penetrated the ore zone that is located in the upper sandstone unit of Salt Wash Member but did not penetrate into the middle or lower portions of the Salt Wash Member. The ore zone is located within the upper sandstone. 6. Addressing Rule 6.4.21 (8) (b) — The EPP discusses, under section 8.3.1 on page U -10, several mapped springs in the area. The unnamed spring was not field identified Please provide the Division with the location and elevation of the Horsethief Spring. Horsethief Springs is located directly east of the LP -21 site at approximately 6300 feet. The location and elevation can be found on Figure U-1 — Geological map. 7. Addressing Rule 6.4.21 (12) — On page U -17, the EPP states that if water is encountered during mining, and chemical analysis determines that uranium related constituents are above regulatory guidelines, then a monitoring well will be installed If groundwater is encountered during mining, a monitoring well shall be installed and a monitoring plan shall be established in accordance with this rule, regardless of the results of the chemical analysis. Please commit to this. 4