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Pit 2 azea, were not conswcted as proposed in the original permit application. No <br />additional mining will occur. <br />Ponds Nos. 1 and 2 are being retained as permanent structures at the mine site, per <br />Technical Revision No. 6, approved by the Division in August, 1991. Pond Nos. 1 and <br />2 were reviewed for compliance with the performance standards of Rule 4.05.9. The <br />designs of both ponds were found to meet the requirements of this section. All ditches <br />and culverts have been removed and reclaimed. <br />Runoff amounts from summer storms are limited based on the low annual precipitation <br />occurring in North Park. Surface runoff leaving the site is largely a function of snowmelt <br />events. NPDES reports have shown that these discharges continue to meet water quality <br />effluent standards. <br />On May 3, 1996, Slurco requested termination of Colorado Department of Health, Permit <br />to Discharge, No. COG-8500]4. The Colorado Department of Health approved <br />termination of COG-850014 on September 25, 1996. <br />A. Probable Hydrologic Consequeuces <br />1. Effects on Surface Water <br />The surface water effects discussed are related only to Bolton Draw, since this is the only <br />receiving stream for waters leaving the Canadian Strip Mine site. <br />The probable hydrologic consequences are limited to a change in the timing of stream <br />flow and minor changes in water quality because of the sediment ponds located on the <br />mine site. It is not expected that the total amount of water will be reduced significantly <br />by evaporation of water contained in the ponds. More likely, there will be only a change <br />in the timing of runoff leaving the mine site because of temporary storage and detention <br />of runoff in the two detention ponds. <br />Surface water quality effects due to mining were identified as a potential for increased salt <br />loading. 'The extent of mining has been decreased from that originally proposed, as Pit <br />2 will not be developed. The pumpage of pit water with elevated total dissolved solids <br />(TDS) concentrations relative to surface water levels will not occur as originally projected. <br />With the continued establishment of vegetation on previously reclaimed portions of the <br />mine site, the effects on surface water quality are considered negligible. <br />Information on surface water hydrology may be found in Appendix C, Volumes I and [I <br />of the permit renewal application. <br />Canadian Strip Mine, C-81-026 20 December 5, 1996 <br />