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4. Division's Comment: It is noted that the Air Pollution Control Division Permit <br />11MF253-1 was modified and issued November 7, 2008. Per Rule 2.03.1, please <br />provide an update to PR-6 submittal page 1-9 to reflect the recently issued permit. <br />Trapper's Response: As requested, Table 1.2-1 was updated to include the most <br />recent modifications to APCD Permit 11MF253-1 and also updates the page with <br />the removal of any reference to APCD Permit 13MF169. Please note that Permit <br />11MF253-1 was updated on May 8, 2009 and now incorporates former Permit <br />13MF169 (Utility Ash and Sludge Disposal). Permit 11MF253-1 is now a combined <br />surface mining and utility ash and sludge disposal permit. The updated permit page <br />1-9 is enclosed. <br />5. Division's Comment: Un-numbered pages discussing Horse Gulch Fill and K/G <br />Buttress Fill provided in PR-6 submittal contain information concerning a <br />description of the proposed fills. Please incorporate the un-numbered pages into the <br />Trapper Mine Permit per Rule 2.05.3(6)(b). The description should include <br />descriptions of the geotechnical investigations, design, construction, operation, <br />maintenance and removal of the proposed fills as applicable. <br />Trapper's Response: A discussion of the construction of the Horse Gulch Fill and <br />the Buttress Fill is included on the attached revised permit text pages 3-40, 3-40a <br />and 3-40b. <br />6. Division's Comment: Based on Appendix A of the Agapito Report entitled Horse <br />Gulch Fill Stability Analysis, December 2008 (The Report), the Horse Gulch Fill is a <br />valley fill by definition. Per Rule 1.04(148), a valley fill "means a fill structure <br />consisting of any material other than coal waste or organic material that is placed in a <br />valley where the side slopes of the existing valley, measured at the steepest poing are <br />greater than 20 degrees or the average of the profile of the valley from the toe of the fill <br />to the top is greater than 10 degrees': Appendix A, Horse Gulch General <br />Arrangement, shows three areas highlighted in yellow that exceed 35% slope (19.17 <br />degrees). Preliminary calculations indicate an average slope for the drainage profile <br />of 8.6% (4.5 degrees). Given that some side slope areas are represented as exceeding <br />a 19 degree slope, Horse Gulch Fill meets the requirements of a valley fill... <br />Therefore the requirements of 4.09.1 and 4.09.2 apply. Please discuss whether you <br />agree with this determination. It may be determined that Horse Gulch Fill may meet <br />the definition of a head of hollow fill in which case the additional requirements of <br />4.09.3 may also apply... Please discuss your position as to whether or not Horse <br />Gulch Fill may also meet the definition of a head of hollow fill. <br />Trapper's Response: Trapper believes that the Horse Gulch Fill meets the definition <br />of a head of hollow fill. Trapper will incorporate an underdrain instead of the <br />alternative chimney drain noted under 4.09.3(1). <br />7. Division's Comment: Page 23 of the Horse Gulch Fill Stability Report states that <br />there will be no need to channel storm runoff away from the fill once the fill is <br />constructed. The Division does not agree with this statement. Small areas south of <br />the fill will flow north toward the fill and require channels designed for the 1.00