2011-03-14_REPORT - C1982056 (3)

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0 2010 ANNUAL HYDROLOGY REPORT 1.0 INTRODUCTION The following Annual Hydrology Report (AHR) presents 2010 hydrologic monitoring data from the Twentymile Coal Company's (TCC's) Foidel Creek Mine located near Oak Creek, Colorado. Hydrologic monitoring locations and specific data results are discussed below. This AHR fulfills the reporting requirements under the Colorado State Division of Reclamation Mining and Safety (DRMS) Permit No. C-82-056. Unless otherwise indicated, all references to "2010" in this report refer to the 2010 Water Year (October 1, 2009 through September 30, 2010). Monitoring results for prior water years are presented in previous AHRs, although selected historical data from prior years are summarized in some of the tables and figures for comparison with 2010 data. Following Section 2.0's discussion of Site Location and Background, this AHR provides Section 3.0 on the TCC 2010 Hydrologic Monitoring Program, which in turn is divided into nine subsections: 3.1) 3.2) 3.3) 3.4) 3.5) 3.6) 3.7) 3.8) 3.9) Bedrock Groundwater monitoring, Alluvial groundwater monitoring, Surface water monitoring, Spoil springs monitoring, Natural springs monitoring, Mine water discharge sites monitoring, CDPS discharge sites monitoring, and Mine inflow study. Water Balance Next follows Section 4.0, discussing Subsidence impacts for local creeks (Fish, Foidel, and Middle Creeks), and lastly Section 5.0, Summary and Conclusions. Tables and Figures are provided in appendices located at the back of this AHR. 2.0 SITE LOCATION AND BACKGROUND The TCC Foidel Creek Mine site is located approximately 20 miles southwest of Steamboat Springs, Colorado, at the south end of Twentymile Park (see Figure 1). This is an active underground coal mining operation, having affected a cumulative total of roughly 8,000 acres in south Routt County through 2010. In 2010 mining affected on the order of 1,300 acres. The primary TCC surface facilities cover about 800 acres, including discharge ponds and railroad loadout areas. The Foidel Creek Mine portals and surface facility areas are bordered on the south and south west by strip mine spoils from the former Colorado Yampa Coal Company (CYCC). Trench and berm rockfall mitigation structures, located north of the primary TCC facilities along county road 27 beneath the Twentymile Sandstone cliffs, covers approximately 30 acres. The coal refuse pile at TCC covers approximately 35 acres. Expansion of the refuse pile footprint will add an additional 140 acres to the refuse pile area (see TR09- 1