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flooded workings of the Oliver Mine, the Sanborn Creek Mine has committed to limited extraction under those areas known • to be flooded. This would avoid catastrophic inundation. The mine has supplied the Division with a geotechnical analysis of the mine plan, demonstrating that it would avoid subsidence-caused fracturing of the interburden. 4. The abandoned Hawk's Nest Mine has several drill holes that were drilled down from the active mine into lower seams. These holes are not believed to be sealed and could provide a conduit through which water could flow into the active mine; however, as reported in the PHC, there is no indication that the mine is flooded. Mine inflow, except that used in the mining process, will be treated and discharged to the North Fork. The discharge will meet NPDES standards, but it is expected that the discharge will have an elevated TDS for which there are no discharge standards. From water quality analyses of the flooded old Somerset Mine, TDS values of 3,200 mg/1 for the discharge can be expected. Post-mining impacts are expected to be small. The mine is expected to slowly flood to the level of the river, which is below the elevation of the portal. Discharge from the portal is unlikely. The water quality of the flooded workings is anticipated to be the same as that of the old Somerset Mine. After mine closure, the proposed Sanborn Creek area is not expected to contribute • additional dissolved solids to the river. Effects on Surface Water The areas of surface disturbance at the Somerset Mine are protected by sediment control systems including diversion and containment ditches, sediment ponds, and other alternate sediment control features such as rock, vegetation and straw filters. All point source discharges are regulated under the National Pollution Discharge Elimination System (NPDES). Specific details regarding the sediment and drainage control systems are found in the Somerset Mine Permit, volume 1, pages 2.05-15, 2.05-16, and 2.05-41 through 2.05-48. Maps E8-3255, 3276, 3277, 3278, and 3279 also contain pertinent information. Drainage and sediment control information specific to the Sanborn Creek Permit Revision area is located in the Permit Revision No. 1 binder, pages 2.05-15, 2.05-16; 2.05-43 through 48, and Appendix B. Drawings 5-002, 003 and 004 also contain pertinent information. Drainage from disturbed areas can contribute additional suspended solids to offsite stream systems; however, the above-referenced sediment control systems will effectively control sediment yield to offsite areas. Other applicable effluent limitations will also be met, as required by the NPDES permit. There is no evidence of acid-forming or toxic-producing materials. -15-