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FROM :AGO NAT. RES. SECTION `' 303 832 9106 1995•1'6-07 08:16 #S75 P.07/18 <br /> the Tunnel. Should maintenance of the portion of the American Tunnel <br /> downstream of the property line seal be undertaken by the property owner or other <br /> parties,then SGC will be released from any continued NPDES permit obligation <br /> at the American Tunnel. <br /> b. Mitigation Projects <br /> SGC will undertake and complete voluntary mitigation projects as set forth in <br /> Appendix; It is anticipated that these projects will allow for final NPDES <br /> permit release wbile maintaining the water quality in the Upper Animas Basin. <br /> SGC will complete all of the "A" List projects and as many of the "B" List <br /> projects as necessary for achievement of that goal. SGC will not guarantee the <br /> long-term effects of the work performed. Plans for each of the projects are <br /> included in Appendix and are hereby approved by WQCD. <br /> C. Cement Creek <br /> The WQCD has expressed concern about potential near-term adverse impacts on <br /> the Animas River from plugging and cessation of treatment at the American <br /> Tunnel. SGC's consultants have not projected such impacts. To allay WQCD's <br /> concerns during implementation of this agreement, SGC will create a temporary <br /> water quality "cushion" within the Upper Animas system to offset potential <br /> additional pollutant loading. To create this cushion, SGC will divert stream flow <br /> from the main stem of Cement Creek(including the North Fork of Cement Creek) <br /> to the current water treatment system for treatment. Upon valve closure at the <br /> Terry Tunnel and at the property line in the American Tunnel, SGC will adjust the <br /> treatment facilities as necessary to accommodate the remaining flow from the <br /> lower American Tunnel and the diverted flow from Cement Creek. This stream <br /> diversion will be regulated in volume from essentially all stream flow in low-flow <br /> months up to the equivalent stream flow lost to the treatment system by scaling <br /> during high flow. This diversion will be monitored and controlled to manage <br /> impacts at the water quality reference point in the Animas River below Silverton. <br /> Once other mitigation steps take effect,the amount of diversion will be decreased <br /> and stopped,following notice to WQCD,when the diversion is no longer <br /> necessary to maintain water quality at the reference point. The water treatment <br /> facility will remain in operational condition until permit release. Upon permit <br /> release,the facility will be dismantled and the treatment ponds and surface <br /> disturbances reclaimed. <br /> �3ca3.1,ds�ss � <br />