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C. Sedimentation Ponds <br />There is one sedimentation pond at the mine, located between the portal bench area and <br />the office facilities area, on the south side of the haul road. The pond treats runoff from <br />the portal bench disturbed area, the upper segment of the haul road surface and cut <br />slopes, and a small supply storage area. The pond is somewhat oversized (storage <br />volume adequate to contain the sediment and runoff from multiple 10 year, 24 hour <br />precipitation events below the level of the 8" primary discharge pipe). In addition to <br />the primary discharge pipe, the pond has an open channel emergency spillway designed <br />for the 25-year, 24-hour precipitation event. The sedimentation pond is discussed in <br />Section 2.4.4 of the text, and designs are depicted on Figure 2.2-3. <br />D. Surface and Ground Water Monitoring <br />GROUND WATER <br />Information provided by the applicant with respect to ground water in the permit area <br />can be found in 4.2.2 through 4.2.4 of Volume I of the permit application. The <br />monitoring plan is described th Section 4.2.4, and monitoring parameters are specified <br />in Table 4.2-15. <br />Issues of concern identified during RN-04 review included the need for clarification of <br />certain discrepancies with respect to the monitoring plan, and impact projection <br />narrative. Also, a drill hole log which was referenced in the narrative had not been <br />included in Appendix G or Table 2.5-1. These concerns were resolved by the operator <br />during the course of the review. <br />As discussed in the Probable Hydrologic Consequences (PHC) section of this document, <br />no significant effects to bedrock or alluvial ground water systems are anticipated for this <br />operation. The applicant will conduct monitoring of ground water in a manner approved <br />by the Division to verify the projections of the PHC. The ground water monitoring plan <br />is as follows (4.05.13(1)): <br />1. Quarterly monitoring of alluvial wells GW-1 and GW-3 for <br />static water level, pH, temperature, and specific conductance. <br />2. Water quality sampling of mine water discharges as requu•ed by <br />NPDES and CDOH permit. <br />3. Monitoring of all non-seep inflows into the mine to include <br />Source, quantity, duration and quality (pH, electrical <br />conductance, and temperature). <br />4. Monitoring of quantities of water discharged from the mine, <br />consumed in the mine, and imported for use in the mine. <br />17 <br />