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~~• ~ _?n_ Water that flows tlrrouyh the active mine area picks up sediment as it comes in contact with the bare spoil and topsoil areas associated with the operation. formally this sediment would pose a pollution hazard to Tuttle Uraw. To mitigate this potential impact the operator has designed and constructed a sediment control system. Most of the water from upland areas adjacent i;o the mine has been diverted away from active mine areas by diversions, ditches, modified channels, or irrigation ditches. Normally, this water arould flow through the mine and increase erosion and sediment yields. By diverting the undisturbed drainage away from active mine areas the erosion potential is yreatly reduced and the volume of water needing treatment is greatly reduced. Water from the active mine area as well as the proposed mining area is or will be routed to a sedimentation pond on the south edge of the permit area (Pond U01). This pond will serve to detain the water for a specified period of tune. During this tune, most of the suspended solids will settle out in the bottom of the pond. By the time the water is released from the pond it will have a low suspended solids content that approaches natural levels. Section 4.03 and 4.05 of the regulations presents specific design and performance standards that mine drainage and sediment control systems must meet. The applicant discussion and engineering designs for pored 001 were reviewed closely to ensure compliance with these rules. Although problems were identified with the system early in our review process, all problems have since then been resolved. The Division finds the system in compliance with these requirements. Five additional sedimentation ponds are in use at this mine (Pond 002, 003, 004, 005, 006 and 007). These ponds drain areas that are in a reclamation phase only. IJO active mining is present or proposed within these areas. Some of the areas draininy to the ponds are pre-law areas that have been reclaimed voluntarily by the operator. Although no mininy is proposed for these areas, the operator will still maintain the areas until bond release. For this reason the Uivision has required Peaboby Coal Company to include the areas and sediment control system within this permit. The Division reviewed the sediment control system for compliance with Rule 4.03 and 4.U5. Concerns were raised with respect to some of the designs. Most of the ponds do not have the storaye capacity required by our Rules. Worrnally, the Division would require the operator to reconstruct the ponds to increase capacity. However, in this case the Division found a strong justification far' not requiring the reconstruction.