2011-06-02_APPLICATION CORRESPONDENCE - C2010089 (10)

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2. The application should contain the specific well completion information for each of the nine new monitoring wells. Table 1 in Appendix 2.04.7-1 is titled "Proposed Ground Water Monitoring Hole Locations and Depths" and contains "Estimated Monitoring Hole Depths". This table should be replaced since the wells have been drilled and constructed. Please add a well completion information table to Appendix 2.04.7-1 that at a minimum contains the following information for each monitoring well: well identification/location, formation monitored, total depth, well casing type and diameter, ground elevation, casing stickup or measuring point elevation, and slotted interval. Response - Corrected 3. There is a typographical error on page 2. In the second paragraph, WFC states that "...water quality monitoring began immediately upon completion of these 9 holes on October 10, 2010." This should read "October 10, 2008". Response - Correction made 4. Groundwater recharge and discharge are described on page 4 and piezometric level maps are provided for each zone (overburden, coal, and underburden) from which flow direction can be ascertained, but there is no specific description of groundwater flow direction and groundwater discharge is described only in general terms. The Division agrees with the general description provided in that the overburden strata is the primary source of discharge to the drainages of Tuttle Draw (to the south) and Coal Canyon (to the west) and that the permeability and porosity will increase with spoil replacement. Add specifics to discussion. WFC states that "discharge is down dip to the outcrops (and old Peabody high-wall) of the stratigraphic zones", but no specific information is given. Discharge rates and flow direction are very important for determining probable hydrologic consequences and the Division believes that these sections on page 4 should be further clarified and substantiated as follows. Reference is made to the New Horizon 2 permit and calculations using Darcy's law are quoted. This information provided is not very useful because the values given require site-specific information including: hydraulic conductivity, gradient, and cross-sectional area which may not be directly applicable to the New Horizon North Mine. Please re-evaluate this information and provide a description of flow direction and gradient for each monitoring zone. Please also describe how the data were obtained for calculating the discharge rates provided (i.e., slug test, pump test etc.). If applicable these data may be useful for predicting or estimating discharge rates for New Horizon North Mine with additional description including flow direction, gradient and cross-sectional area. Please update page 4 of the application accordingly. Add discharge rate calculations. Response - Page 4 has been updated and discharge rate calculations have been added 5. Aquifer characteristics are described on page 5 but similar to Item 4 above there is reference to the New Horizon 2 permit and also to the New Horizon 1 Mine Area permit. Any pertinent information regarding data for the New Horizon North Mine should be readily available and provided in this NHN application. There is reference to a short term capacity test and transmissivity test at Well GW-N27 which is not located within the NHN permit area, but it is not clear if any actual aquifer testing was conducted or how the data were obtained. Please Response to First Adequacy Review Page 16