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Possible slides from this cut slope do not present a potential for serious <br /> environmental harm. Any small debris from the cut slope or cliff above is <br /> contained by the roadside ditch system that is regularly maintained and directs <br /> drainage to the sedimentation pond. In the event of a slope failure at this <br /> location, slide material would likely block the drainage ditch and accumulate on <br /> 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 <br /> slope nor the upper cliff slope above the cut have demonstrated instability since <br /> the crest slope reduction was performed. For these reasons,the Division finds <br /> that the cut slope steeper than Iv:0.25 in rock will not result in significant <br /> environmental harm or harm to the public health and safety (4.03.1(3)(d)(i)). <br /> II. Support Facilities—Rule 4.04 <br /> Support facilities are discussed under Section 2 of the permit application. <br /> Construction of support facilities will not result in damage, destruction, or disruption of <br /> oil, gas, or water wells or pipelines, coal slurry pipelines, railroads, or utility lines which <br /> pass over,under, or through the permit area. Utility lines pass through the permit area but <br /> are not affected by the support facilities. Therefore,the Division previously approved <br /> those activities (4.04(6)). <br /> III. 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 <br /> ditch to a sedimentation pond, to ensure that all discharges meet effluent limits specified <br /> in the CDPS discharge permit for the McClane Canyon Mine. <br /> A storm water permit also dictates measures for ensuring that all surface runoff water <br /> leaving the mine site meets applicable effluent limits. Three small disturbed areas: the <br /> office area,topsoil stockpile, and construction dirt stockpile, are not routed to a sediment <br /> pond, and are approved as small area exemptions (SAE's). In these areas, sediment <br /> control is provided by diversion berms and silt fencing demonstrated to be sufficient to <br /> ensure that runoff from the 10 year, 24-hour storm event will meet the settleable solids <br /> discharge limit of 0.5 ml/l (Appendix pages M-2 through M-4xxiii of the PAP). The silt <br /> fences were approved within TR-I I to replace total containment sumps that had <br /> previously provided sediment control for the small areas. The silt fencing was installed in <br /> 2002. <br /> Mine water collected underground in sumps is authorized within the NPDES permit to be <br /> pumped to the surface and directly discharged through a pipe to the McClane Drainage <br /> without being routed through a sedimentation pond. Mine water discharges have been <br /> xiv <br />