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1. The applicant will conduct monitoring of ground water in a manner approved <br />by the Division. The ground water monitoring plan can be found in Section <br />4.8.5.2a, Vol. IV of the permit application (4.05.13(1)). <br />2. The applicant will conduct monitoring of surface water in a manner approved <br />by the Division. The monitoring plan was submitted under 2.05.6(3)(b)(iv) <br />and can be found in Section 4.8.5.1 a of the permit application, Vol. IV <br />(4.05.13(2)). <br />The Division has reviewed the surface and ground water monitoring plans as part <br />of the revision process. These monitoring plans are adequate to monitor for the <br />development of impacts, if any should develop. The 2003 Annual Report <br />stipulated existing water monitoring well GP-09 as the groundwater point of <br />compliance. <br />No new or revised water monitoring is being proposed under PR-06. <br />E. Probable Hydrologic Consequences <br />The model for leachate formation and migration at the Trapper Mine is based on a <br />study conducted by the U.S. Geological Survey at the Seneca II Mine in Routt <br />County, approximately 14 miles east of the Trapper Mine (U.S. Geological <br />Survey Water Resources Investigations Report 92-4187). The model is described <br />in the probable hydrologic consequences of the permit application (section 4.8), <br />and is summarized below. <br />Ground Water Impacts: <br />Leachate formation - Slightly acidic snowmelt and rainwater at the Trapper <br />Mine infiltrates into the spoil that fills the reclaimed pits and fill structures (K-Pit <br />Buttress Fill and Horse Gulch Fill). Groundwater may also seep into spoil from <br />adjacent or underlying rocks. As the water percolates through spoil, chemical <br />reactions occur with the spoil. The main reactions are dissolution, pyrite <br />oxidation, and cation exchange. These reactions enrich the infiltrating water with <br />minerals from the spoil, forming a leachate that has high levels of dissolved <br />solids. The leachate is alkaline, magnesium-sulfate type water. The <br />concentration of dissolved solids can be predicted to not exceed 5,000 mg/1. The <br />leachate samples at Trapper have remained in the range of 1,100 to 4,100 mg/l. <br />Leachate quality predicted by batch leaching tests - Batch leaching tests <br />performed by the applicant indicated that the metallic constituents in coal spoil at <br />Trapper which are most likely to form a leachate are manganese, molybdenum, <br />and vanadium (section 4.8.2.5 of permit application). As of 2008, high levels of <br />manganese have been detected in samples from three of the four wells on Trapper <br />that monitor water quality in spoils-filled pits (wells GD-3, GD-5, GD-7, and GF- <br />11) [Appendix W of permit application]. Molybdenum and vanadium have not <br />been detected in samples from the four wells. <br />Trapper Mine 25 September 21, 2009