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of excess bond would allow the operator to reduce their reclamation liability bond by <br />$2,027,758.72. <br />Description of the Environment <br />The Seneca II -W Mine is located in northwest Colorado approximately 7 miles south of Hayden <br />in Routt County. The Seneca II -W Mine lies 7 miles west of Sage Creek Mine, Permit No. C- <br />2009-087 and 3.5 miles west of the Yoast Mine, Permit No. C-1994-082. The mine is located <br />between two formerly permitted operations, Grassy Creek Mine to the east, and Hayden Gulch <br />Mine to the west. The mining area can be found on the Hayden, Hayden Gulch, Mount Harris and <br />Dunkley Quadrangles 7.5 Minute Series Maps. The coal from Seneca II -W was hauled over county <br />and private roadways by private hauler to the Hayden Station Power Plant operated by Public <br />Service of Colorado. Haulage distance is approximately ten miles each way. Baseline <br />environmental information collected for the Seneca II -W Mine can be located in Tabs 4 through <br />11 in the permit application. <br />Geology and Topography <br />Elevation of the general mine site varies from approximately 6400 to 8350 feet. Slopes range from <br />about 2 percent to nearly 100 percent. Prominent ledges are formed by the Twentymile sandstone <br />in the western permit area and the Trout Creek sandstone ledge in the eastern permit boundary. <br />Many of the drainages are deeply incised. <br />The Seneca II -W Mine is situated in the southeastern synclinal portion of the Sand Wash Structural <br />Basin of northwestern Colorado and south central Wyoming. Exposed strata near the mine site <br />vary in age from Late Cretaceous to Quaternary. Most units in the area are sedimentary. However, <br />some Miocene extrusives are locally present. Many faults and folds modify the regional synclinal <br />structure; however, no faults have been identified at the site. The most significant local fold is the <br />Sage Creek Anticline, located just east of the mine. Rock units dip 8 to 14 degrees to the west. <br />The Seneca II -W Mine lies on the western flank of this anticline. The largest local structure is the <br />Tow Creek Anticline, located about 10 miles northeast of the permit area. <br />The local stratigraphic sequence, in ascending order, is the Mancos Shale; the Mesaverde Group, <br />which is subdivided into the Iles and Williams Fork Formations; and the Lewis Shale. See the <br />Exhibit 6-GX geologic cross section map series in the permit application package for further detail. <br />The Iles Formation is divided into three members. The basal Tow Creek Sandstone is a massive, <br />fine-grained, well -sorted sand. The Tow Creek varies from 35 to 125 feet thick. Overlying the <br />Tow Creek are 1200 feet of interbedded shales, sandstones, and coals. The coals, while mined in <br />the vicinity, are too deep to be considered economically recoverable at the Seneca II -W Mine. <br />The massive, fine grained, 100 feet thick Trout Creek Sandstone is the uppermost unit of the Iles <br />Formation. <br />Conformably overlying the Iles is the Williams Fork Formation. The lower unit of the Williams <br />Fork Formation is a series of interbedded shales, sandstones, sandy shales and coal. The middle <br />vii <br />