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Attachment N111C <br /> Page No. MHC- 4 <br /> Permit No. CO-0044768 <br /> Description of Protect <br /> —Inlet structures will be constricted in drainages A and C (see included maps) to capture the surface <br /> drainage before it goes underground. These structures will divert the (low into buried ADS pipe for <br /> transport to Sunnyside's existing storniwatcr diversion ditches. If required to prevent leakage, these <br /> existing diversion ditches will be up-graded by installation of an invert liner. In the event that a <br /> buried pipeline is found to be impractical, the existing drainage paths A and/or C will be cleaned and <br /> shaped to accept an invert liner(40 mil PVC). This liner material will be covered with dirt and annor <br /> material to protect the liner from tears associated with rock scour in high flow events. These <br /> pathways lead to Sunnyside's existing stormwater diversion ditches <br /> —Drainage path B is not a clearly defined natural drainage channel but topography indicates that it is <br /> a drainage path and surface floes have been observed infiltrating to flow as groundwater along this <br /> rock defined pathway. A point has been defined where it may be possible to expose bedrock. At this <br /> point, an interception structure will be constricted to capture the flow and divert it into a buried ADS <br /> pipe for transport to the existing stormwater diversion ditch. If the bedrock contact cannot be <br /> technically and economically exposed for constriction of the interception structure, drainage path B <br /> will not be intercepted <br /> —Revegetation of am \egetation disturbed by constriction. <br /> —Stormwater sediment control will be used as necessary to minimize sediment transport from the <br /> site. <br /> Analysis <br /> Installation of structures and control of drainage to minimize the potential for water to contact <br /> tailings and mine waste material is a Best Management Practice. Any reduction in contact of mine <br /> waste or tailings with no\\ing w titer has the potential for reduction in metals loading to the Animas <br /> RiN er <br /> This project is significantly up-gradient from Sunnyside's Stormwater and MLR Permit boundary <br /> and if assumptions made are correct, then significant improvement to water quality in the Animas <br /> River could be realized If the springtime variances in water quality detected by Sunnyside's MLR <br /> permit monitoring is due to background mineralization, as some up-gradient seep and spring samples <br /> indicate, this project may reduce metals loading to the Animas River Implementation of the work <br /> plan will not nnateriall alter the land or create any land use changes or potential uses. <br />