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CESI'K-CO-R Public Notice Number 199475346 Mined materials are deposited directly into trucks or other hauling equipment and hauled over roadways routed along elevated sand and gravel deposits to the stockpile and processing area on the west bank for storage. Where flowing water is encountered within the roadway alignment, culverts are installed. Usually, this involves one main river crossing made up of nine culverts (36-inches in diameter and 30-feet long) and one smaller crossing as needed made up of two culverts (24-inches in diameter and 30-feet long) packed with native alluvium. Every reasonable effort is taken to prevent the entry of sediment to the river system. In addition to temporary fills associated with dikes and culverts, some spillage of sand and gravel materials occurs during the excavation, loading, and transporting process. The amount of spillage is roughly estimated to be less than 50 cubic yards a year. Within the project vicinity, the Animas River bed sediments are comprised primarily of heter~~geneous unconsolidated cohesive particles ranging in size from sand to course cobbles. Appn~ximately three percent by weight of extracted materials are smaller than a number 200 mesh sieve with essentially none of the material in the clay size. Attached to this public notice are subazmor bed material gradation curves further depicting the composition of bed material at this site. Based on the low concentration of small fine materials, sediment pollution into the active channel is believed by the applicant to be very minor. In addition, because mining activities occur during low flow periods, any material that enters the flowing water during installation of culverts or dike construction quickly settles within the limits of the Dalton Pit. Prior to high water flows, all temporary isolation dikes, haul roads, and culverts are --- removed to conform with the existing streambed. Upon demand, materials aze crushed, washed, and separated according to size by classifying and screening. Wash water is not discharged directly into the Animas River, but is disposed of by subsurface percolation from a settling pond located on the west bank at the south end of the permit area. The settling pond is periodically cleaned to assure that there is no overflow to the river from stormwater runoff or other anticipated high flow events. Based on this method of handling, a Section 402 discharge permit is not required from the Colorado Department of Health Water Quality Control Division. Dredged pond materials are stored in the stockpile area just north of the pond. From the stockpile and processing area, materials are trucked off-site to consumers. The applicant states ... "This method of controlled mining contributes to the stability of the river system by preventing the accumulation of sediment within the channel, thereby decrezsing the probability of flooding by reducing the flood stage that would otherwise result from aggradation of the bed. Additionally, this method of mining does not increase the existing channel bank heights and so does not contribute to accelerated bank erosion and no detrimental impacts to local or off-site azeas are expected. Further, this type of mining operation does not involve the removal of existing riparian vegetation or the alluvial soil overburden." ALTERNATIVES: The no action would result in permit denial and essentially require the in-stream operations to cease. This alternative would possibly require the applicant to mine upland areas within their permit boundaries. 2 •