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2. The Division proposes to approve the alteration or relocation of a natural channel <br /> drainageway located on the lower segment of McClane Canyon drainage, between the <br /> construction dirt storage area and the office facility area. The operator has demonstrated <br /> (Appendix M,pages M-5 through M-9)that the natural channel drainage will not be blocked, <br /> no significant damage will occur to the hydrological balance, and no adverse impacts will <br /> occur to adjoining landowners(4.03.1(4)(a)(i)). <br /> U. HYDROLOGIC BALANCE-Rule 4.05 <br /> A. Water Quality Standards and Effluent Limitations <br /> All surface drainage from the mine bench/face-up area is directed via the road drainage ditch to <br /> the sedimentation pond, to ensure that all discharges meet effluent limits specified in the CDPS <br /> discharge permit for the McClane Canyon Mine. The sediment pond was filled in with sediment <br /> by a 100 year magnitude storm event in August 2001 that had buried and overwhelmed one of the <br /> primary upland diversion culverts. In association with excavation of sediment,the inside slopes of <br /> the sediment pond were reduced to approximately 2H:IV. The re-constructed pond was properly <br /> certified by a professional engineer(see"Impoundment Yearly Inspection"of March 29,2002). <br /> A storm water permit also dictates measures for ensuring that all surface runoff water leaving the <br /> mine site meets applicable effluent limits. Three small disturbed areas; the office area, topsoil <br /> stockpile, and construction dirt stockpile, are not routed to a sediment pond, and are approved as <br /> small area exemptions (SAE's). In these areas, sediment control is provided by diversion berms <br /> and silt fencing demonstrated to be sufficient to ensure that runoff from the 10 year,24-hour storm <br /> event will meet the settleable solids discharge limit of 0.5 mill (Appendix pages M-2 through M- <br /> 4xxiii). The silt fences were approved within TR-11 to replace total containment sumps that had <br /> previously provided sediment control for the small areas. The silt fencing was installed in 2002. <br /> Mine water collected underground in sumps is authorized within the NPDES permit to be pumped <br /> to the surface and directly discharged through a pipe to the McClane Drainage without being <br /> routed through a sedimentation pond. Mine water discharges have been necessary on occasion <br /> since resumption of operations in 2000, and the discharges have been in compliance with <br /> applicable discharge permit effluent limits. <br /> Drainage and sediment control measures are addressed in Section 2.4.4 of the application text, as <br /> well as various exhibits and appendices referenced in the text. Sections of the text and appendices <br /> were amended to eliminate certain inconsistencies identified by the Division during the renewal <br /> review. The following finding is made pursuant to the three small area exemptions referenced <br /> above. <br /> 1. The Division proposes to grant small area exemptions (SAE's) from use of sediment ponds <br /> for the office facility area (SAE-1, .78 acres), the topsoil stockpile (SAE-2, .39 acres), and <br /> the construction dirt stockpile(SAE-3, .30 acres) due to the limited size of the areas and due <br /> to the fact that the operator has demonstrated that ponds and treatment facilities are not <br /> necessary for the drainage to meet the effluent limitations of Rule 4.05.2 and applicable State <br /> and Federal water quality standards for receiving streams, and also due to the fact that no <br /> mixing of surface drainage with a discharge from underground workings will occur <br /> (4.05.2(3)(b)(i). <br /> 13 <br />