2025-05-02_REVISION - C1981010 (2)

Home Browse Search

information is presented in Section 2.7.5.2 of the currently approved PAP (Page 2- 463). Water quality has been monitored at five different locations at the mine site; Sites GA, GB, GC, GD and GE. 2. The applicant will conduct monitoring of surface water in a manner approved by the Division. The monitoring plan was submitted under 2.05.6(3)(b)(iv)and can be found in Section 4.8.5.1a of the permit application,Vol. IV(4.05.13(2)). The Division reviewed the surface and ground water monitoring plans as part of previous permit revision review processes and the most recent Annual Hydrology Report of 2023. DRMS deemed the monitoring plans in place adequate in monitoring for the development of impacts, if any should develop. Well GP-09 has been designated the groundwater point of compliance for the Third White Sandstone aquifer, and the Coy well is the point of compliance for the Flume Gulch alluvium. The applicable standard at the points of compliance is the Interim Narrative Standard from Regulation 41, The Basic Standards for Groundwater(Reg 41). Water monitoring is in place down dip of the I and J pits near the Coyote Pond for the pits as they develop to the west. These wells have been drilled under the MR225 permitting action and monitor the First, Second and Third White Sandstone aquifers. New or revised surface water monitoring is in place associated with new pond construction in the East and West Buzzard drainages. E. Probable Hydrologic Consequences The model for leachate formation and migration at the Trapper Mine is based on a study conducted by the U.S. Geological Survey at the Seneca II Mine in Routt County, approximately 14 miles east of the Trapper Mine (U.S. Geological Survey Water Resources Investigations Report 92-4187). The model is described in the probable hydrologic consequences of the permit application (Section 4.8). No drawdowns have been detected in aquifer wells within one mile from the permit boundary. Observed drawdowns have been temporary and are limited to the immediate vicinity of the pits. The operator expects such limited drawdowns to continue with future mining. The proposed mining operation will have little if any effects on the post-mining recharge capacity. The applicant's studies concluded that the recharge capacity of the reclaimed spoils will be slightly higher than the pre-mine condition. The mine activities should not impact any regional aquifers except the Third White Sandstone. Mined strata dip far beneath the Yampa River alluvial aquifer and communication between these strata and the alluvial aquifer is negligible. Permit section 4.8.2.2 discusses potential drawdown impacts to adjacent wells. A groundwater monitoring program is discussed in section 4.8.3.2 of the permit. Point of compliance wells are in place. Surface Water Impacts Surface water flow and quality are monitored in the Flume System, Johnson Gulch, No Name Gulch,Ute Gulch, Pyeatt System, Oak, Gulch, Horse Gulch and Deal 14