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3. The underground mine workings would intercept ground water currently flowing toward Twentymile Park, and discharging to the Fish Creek stream/alluvial aquifer system. The applicant should provide an analysis showing the extent to which flow would be decreased in the Fish Creek system. This could be approached by first assessing the quantity and relative significance of the flow passing through the potentially affected area, and then predicting the effect of intercepting this water and discharging it to the Foidel Creek drainage. Water quality impacts should be taken into consideration. Possible effects to the downstream users of surface flow and alluvial ground water should be considered, and mitigations proposed if appropriate. Modeling techniques would be appropriate to facilitate this analysis. 4. The reestablishment of natural ground water movement, poatmining, would cause a plume of degraded ground water to migrate towards Twentymile Park and discharge to the Fish Creek steam/alluvial aquifer system. As a result, water quality in ,_ the Fiah Creek system could be altered. The permit application contains a qualitative discussion conerning the migration of this plume, but the assessment needs to be quantified to verify the appicant's conclusions. If the quantitative assessment indicates that water quality in the Fish Creek system would be affected, possible effects to downstream users should be evaluated, and appropriate mitigations proposed. 5. The applicant has included a description of the runoff and sediment control system that would be used to meet the normal effluent limitations (T55, Iron, Manganese, pH). However, the Coloado Department of Health has established additional numerical standards for 27 water quality constituents (Attachment B) for all tributaries in the Troui Creek drainage. Since Foidel Creek is an intermittent stream, the effluent itself should meet these standards. The applicant should demonstrate that effluent from the mine site would meet the specific numerical limitations or provide a plan for treatment of the effluent for those standards which are exceeded. (The Division is particularly concerned with the discharge of water from the mine workings and from the spoils dewatetinq well in Section 27.) Surface and Ground Water Monitotinc As requited by Rule 2.05.6(3)(b), the applicant has submitted surface and ground water monitoring plena (Exhibit 10). A preliminary review of this plan has identified several concerns.