2010-12-17_REVISION - C1981019 (108)

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RULE 2 PERMITS originating from infiltration into the Collom Lite pit would return to normal. Other than those directly eliminated by the pit, no springs are likely to be affected by the Little Collom X pit. Potential Surface Water Quality Impacts Potential impacts to the surface water quality from the proposed Collom Lite and Little Collom X mining operations are considered here. As described above, Little Collom Gulch is ephemeral, and showed no evidence of surface flow during 18 months of baseline monitoring. There is therefore no basis on which to determine relative changes in surface water quality for Little Collom Gulch. Potential mining impacts will be limited to the shallow valley fill groundwater regime, discussed elsewhere, rather than surface water. The West Fork of Jubb Creek is intermittent, and is only affected by a potential reduction in spring/seep source area by construction of the Collom Lite pit. Water infiltrating into reclaimed pit and spoil areas may later enter the West Fork of Jubb Creek via springs, if the elevation of the springs is below the final pit outflow elevation, and if the spring is connected to a stratigraphic interval that is exposed along the downgradient highwall of the reclaimed pit. The reclaimed pit outflow elevation is 7290 amsl, while the potentially affected springs are either located above this elevation, or have a source stratum which falls above this elevation where it intersects the highwall. Springs V 10 and V32 are located above the pit outflow, at elevations 7295 and 7600, respectively (based on 25 foot contours). Spring/seep V 1 is located at approximate elevation 7170, below the pit outflow, but is roughly 3200 feet from the pit disturbance boundary, not accounting for the highwall side slope. VI is generally down -dip from the pit, and the bedrock dips at roughly 8 percent. The spring's source layer must therefore intersect the highwall approximately 256 feet (3200 x 0.08) above the spring elevation, or roughly 7426 ft amsl. This is well above the pit outflow elevation. Therefore, water in contact with the overburden fill will not impact water quality in the West Fork of Jubb Creek, and will instead discharge to groundwater, generally within Little Collom Gulch. Other Potential Impacts Flooding and stream flow regime do not appear to have been affected by past mining operations or reclamation, nor are they anticipated to be affected by Collom Lite and Little Collom X mining. Groundwater availability in the area may potentially be enhanced with the storage of water in the reclaimed pits. Colowyo owns significant water rights within the affected drainages. Any potential diminishment of flow will be compensated for by reduced use by Colowyo. There is sufficient capacity for Colowyo to reduce their use of adjudicated water to compensate for potential diminishment of flow, allowing downstream users full access to their water rights. 2.05.6 (4) Protection of Public Parks and Historic Places No public parks are located within the permit or adjacent areas; therefore no public parks will be affected by the proposed mining operations. The proposed mining operations are anticipated to affect specific sites and areas listed or eligible for listing in the National Register of Historic Places. These sites are discussed in further detail in Sec 2.04.4. A treatment plan has been prepared for some of the sites expected to experience impacts from the development of this mine. This treatment plan will identify specific mitigation processes needed to develop in and around these sensitive locations. 2.05.6 (5 -6) Surface Mining near Underground Mining; Subsidence Control No surface mining activities will be conducted within 500 feet of an underground mine. Therefore, there is no subsidence control plan for proposed operations. Collom — Rule 2, Page 130 Revision Date: 1/23/09 Revision No.: PR -03