2015-08-18_PERMIT FILE - C1982056A (4)

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Modeling of surface water conditions has been utilized as set forth in Exhibit 8, Sediment Control Plan. Characteristics of surface runoff, peak flow, reservoir routing, sediment yield, and theoretical detention time have been modeled using the techniques described in "Procedures for Determining Peak Flows in Colorado' (USDA, SCS 1977) and "Applied Hydrology and Sedimentology For Disturbed Areas" (Barfield, Warner and Haan 1981). These techniques have been incorporated into the DEPOSITS model, which has been utilized in the design of treatment facilities for the underground mine. Finally, streamflow and water quality in streams draining the general area has been modeled using the WATBAL model, for the purposes of the assessment of probable hydrologic consequences of mining on surface water, required by Rule 2.05.6(3). Modeling of ground water conditions has been utilized in this application, specifically under Rule 2.05.6(3) and in Exhibit 9, Aquifer Test Data. Dewatering, drawdown and solute transport characteristics have been modeled using the analytical methods described in "Ground Water Hydraulics" (Lohman 1979), "Selected Handheld Calculator Codes for the Evaluation of the Cumulative Hydrologic Impacts of Mining" USDI Office of Surface Mining 1981, and the finite- difference GRWATER computer model described in "Ground Water Hydrology and Hydraulic" (McWhorter and Sunada 1977). (3) Permit applications may comply with the requirements of 2.04.5(1), 2.04.6(1)(a), 2.04.6(2)(a) and 2.04.7 by providing accurate descriptive and predictive information relating to geology, water gualfty and quanti1y for the area to be affected over the estimated life of the operation based upon extrapolation by an expert in the field from documented data on the geology, water quality and quantity of similar areas, provided that the data used by the expert is included within the permit application, the expert opinion is approved by the Division and all such data are made available to the oublic for review and comment. RESPONSE The information and analysis referenced above represents over five years of data collection in the permit and adjacent area by Federal and State agencies, private organizations and universities. Conclusions and opinions of experts of each field may be found in the accompanying exhibits. The conclusions and opinions were derived by extrapolation of the data collected in the permit and adjacent areas. Rule 2.04.6 - GeolOLyy Description (1) General Requirements The geology description shall include a description of the geology (stratigraphy and structure) within the proposed permit and adjacent areas. This description shall be sufficient in detail to: (a) Define the relationship between structural geology and the occurrence, movement, quality and quantity of potentially impacted surface and groundwater; (b) Assist in determining the feasibility of the proposed reclamation plan; (c) Assess the potential for off -site material damage to the hydrologic balance; (d) Assist in the preparation of the probable hydrologic consequence statement and the establishment of the hydrologic monitoring plan; and (e) Assist in the preparation of the subsidence control plan under 2.05.6(6). RESPONSE The information required by this rule can be found in the responses provided to Rule 2.04.6 (3). The text for this response starts on page 2.04 -12.1 and onto 2.04 -19. This referenced section addresses the general geology discussion required by this rule. Additional information addressing the hydrologic component of this rule can be found in Rule 2.04.7. The text for this rule can be found on pages 2.04 -19 through 2.04 -43. In reference to the geologic information presented and the overburden characterization associated with addressing the feasibility of the reclamation plan it should be noted that the TCC facilities are located next to the Colorado Yampa Coal Company reclaimed surface mine. The surface mine has been successfully reclaimed and the TCC surface facilities will utilize the same resources and reclamation techniques as applied to the surface mine. MR14 -282 2.04 -12 09/08/14