2013-04-18_PERMIT FILE - C2009087 (6)

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RULE 2 - PERMITS 2.04.5 General Description of Hydrology and Geology ]'his application contains comprehensive and detailed descriptions and maps concerning the geology and hvdrolog} of the proposed permit area. adjaCellt area. and the general area. The definitions of these areas. as contained in Rule 1, Section 1.04, have been applied. in «hat PSCM believes to be a reasonable nial ncr. to the lands surrounding the planned mining operation. The PSCM permit area contains all lands on which the operator \\Ill conduct Illinilh) operations dlll'llh) the term Of the permit. The adjacent area covers lands and resources outside the PSC 1\I perllllt area «hlch may be affected b} minim, operations. The general area includes the topographic and groundwater basin surrounding the area to be IllllleCl. 11]Cllldlllg one of more watersheds containing perennial streams and groundwater s\ sterns. The general area is of sufficient size to allow assessments of curnulati� e hydrologic impacts in the basin. This section specifically addresses the general area with regard to geology and hydrology. The information presented in this section is based on research of available published reports and documents: contacts with Federal. State. and local a0encies: site - specific investigations: and ongoing monitoring activities. A map of the larger region that contains the Hayden Syncline Basin general area is shown on Map 2.04.5 -M1, Regional Geology and Hydrology. The PSCM permit area includes all lands to be undermined or disturbed by mining activities over the life of the mine. It is drained primarily by Grassy Creek and its tributaries towards the north. and minor tributaries of Fish Creek towards the south and southeast. The proposed general area for surface water hydrology includes the entire watershed of Grassy Creek to its confluence with the Yampa River, and the western tributary \�atcrshcds of fish Creek lying within the ` OLItlet fish Creek" hydrologic unlit, ending at the confluence of Fish Creek with Trout Creek. A logical structurally defined boundary for geology and hydrogeology for the PSCM general area is the anticlinal axes of the Tow Creek anticline on the east and south and the Fish Creek anticline on the x\est. Information on the geology and surface and groundwater systems for all lands within the PSCM permit area and adjoining area described above is included under Sections 2.04.6 and 2.04.7 of this application. Regional and General Area Geology The PSCM is situated within the southeastern synclinal portion of the Sand Wash Structural Basin of northern Colorado and central Wyoming (Bass et al., 1955), also known as the Yampa Coal Field. Figure 2.04.5 -F1, presents a geologic depiction of the Yampa Coal Field. The Sand Wash Basin is part of the greater Green River Region which includes the Washakie Basin, the Great Divide Basin, and the Green River Basin. The sub - basins are separated by uplifts caused by deformation of basement rock. The Sand Wash basin is bordered to the southwest by the Axial Basin Anticline, to the north by Cherokee Arch, and the east by the Park Range Uplift, or Anticline (CGS, 2003). The Sand Wash Basin covers approximately 5,600 square miles and is primarily located in Moffat and Routt Counties, Colorado (EPA, 2004). Topography in the region ranges from gently sloping valleys to deeply incised slopes and vertical cliffs. The form of the land surface is greatly affected by the lithologic and structural setting of the local area. Deeply incised slopes occur primarily on the eastern limbs of the Sage Creek, Fish Creek, and Tow Creek Anticlines while low- relief, gently rolling terrain overlies the axis of the Sage Creek and Hayden Syncline. Midterm Review 2.04 -15 Revision 04/2013