2011-08-09_REVISION - C1981019 (10)

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• • RULE 2 PERMITS As noted in the previously submitted text, alluvial materials are present in the valley bottoms of the Collom Gulch drainages but the materials are intermixed with significant fractions of colluvium and sheetwash from adjacent slopes. This can be seen in the geologic description of the monitoring well (MC- 04 -02) in the lower portion of Collom Gulch in Section 24, T. 3 N., R. 93 W. The cuttings obtained from the drill hole are predominantly silty clays, with minor amounts of sand and gravel ( <25 %). Based on depth to groundwater in this drill hole (10 feet below ground surface), it is doubtful that subirrigation of any plant crop is possible. Further to the north, near the confluence of Collom Gulch and Little Collom Gulch, monitoring well MLC- 04 -01, has a ground water level of between 40 and 50 feet below ground water surface. In addition, active erosion in the Collom Gulch channel is causing further incision, which is lowering the unconfined groundwater table found in the valley. The incision in Collom Gulch is at least two feet and in excess of 20 feet in sections before that flow of Collom Gulch exits through the `hogback' and flows onto the Mancos Shale located in the Axial Basin to the north. The incision is also widening due to the downcutting and erosion of the supporting banks during periods of higher flow (normally occurring during the spring). With the low surface water flow rates and the reduced flood frequency, this has reduced the ability of the valley bottoms to support any agricultural use other than rangeland. Local and regional agricultural economics are prohibitive to developing irrigation projects within these valley bottoms, and such practices are in decline locally, especially on such a small scale as would be required by the narrow and fragmented nature of irrigable bottomlands within the subject drainages. The narrow width and fragmented nature of the minimal flat land, depth to ground water, and impracticality of economically irrigating or mechanically farming the valley bottoms within Collom Gulch indicate that those drainages do not qualify as alluvial valley floors. In conclusion, no adverse impact to the water environment downstream of the reclaimed Collom Lite pit is projected. 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 141 Revision Date: 8/5/11 Revision No.: PR -03