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The Division proposes to approve the following specific variances. <br />A. Haul Roads <br />The Division proposes to approve cut slopes steeper than 1v:0.25h in rock. Figure 2.2-5 of <br />the application indicates a section of the road which had to be cut into the canyon wall where <br />the cut slopes are approximately 1v:0.13 horizontal (cross section C-C'). A safety hazard <br />posed by the steep upper portion of the cliff in this location was mitigated by the operator by <br />gading the crest of the slope to a lesser grade, in the spring of 1988. <br />Possible slides from this cut slope do not present a potential for serious environmental harm. <br />Any small debris from the cut slope or cliff above is contained by the roadside ditch system <br />Yhat is regularly maintained and directs drainage to the sedimentation pond. In the event of a <br />slope failure at this location, slide material would likely block the drainage ditch and <br />accumulate on the road. Any such blockage of the drainage system would be temporary and <br />would not result in significant environmental damage. Neither the road cut slope nor the <br />upper cliff slope above the cut have demonstrated instability since the crest slope reduction <br />was performed. For these reasons, the Division finds that the cut slope steeper than 1 v:0.25 <br />in rock will not result in significant environmental harm or harm to the public health and <br />safety (4.03.1(3xdxi)). <br />^. 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 a <br />sedimentation pond, to ensure that all discharges meet effluent limits specified in the CDPS <br />discharge permit for the McClane Canyon Mine. <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). -n 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 m]/I (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 undergound in sumps is authorized within the NPDES permit to be pumped <br />to the surface and directly discharged through a pipe to the McClave 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. The following finding is made <br />pursuant to the three small area exemptions referenced above. <br />13 <br />