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Oxbow Alinin¢r LLC- T}rhnitat Revirian TRd3 11 IF'er/ Coat Refart FatiGty TerbnirotAdegnary Comment/Raponrer September S, 2003 Pagr 2 7) Ou.rheet S.of 5 of Drawing 2.05-M4, the east end of the IIW upper haul road ditch is shown to travel uphill before it emptier into IIW culvert 1. Please revile the positions of there two ditch and culvert rymbolr shown an Drawing 2.05- M4, sheet 5 of 5. Response: On Map 2.05-M4 (Sheet 5 of 5), the culvert symbol has been shortened and. the ditch symbol shifted to more accurately reflect the anticipated configuration and relationship of these drainage components. Copies of the revised map accompany these responses for replacement in the Mining and Reclamation Plan document. 8) On sheet 5 of S of Drawing 2.05-M4, pleare add the permit boundary line to the droving and in the droning legend Response: The segment of permit boundary that falls within the area mapped on Maps 2.05-M1 (Sheet 5 of 5), 2.05-M4 (Sheet 5 of 5), and 2.05-M6 (Sheet 5 of 5), has been added to the maps and noted in the map legend. Copies of the revised maps accompany these responses for replacement in the Mining and Reclamation Plan document. 9) On sheet S of 5 of Drawing 2.05 M4, please add drainage rymba4 for the bench ditcher krated on the IIW gob pile. Response: As requested, Map 2.05-M4 (Sheet 5 of 5), has been revised to add the bench ditches on the coal refuse pile. Copies of the revised map accompany these responses for replacement in the Mining and Reclamation Plan document. 10) Because of the proximity of the railroad line to the Pond E concrete darn, the Division believer that Pond E should be dasr~ed ar a Clan B dam, ar defined in Technical Releare No. 60 (IR60) of the U.S. Department of Agriculture, Ortaber 1985. As required in Ruler 4.05.9(2)(d) and 4.05.9(10), pleare provide Serkad derignr that demonstrate that the emergenry spillway of Pond E ran parr the precipitation event, With the required freeboard, at dcfrned in Table 2-S afTR60. Response: The dam classifications and corresponding design provisions outlined in TR-60, aze applicable only to "eazth dams" defined in TR-60 as: " a dam in which the principal barrier is an embankment of eazth or rock fill or combination of earth and rock fill." Given that the proposed structure is a concrete embankment, the provisions of TR-60 aze not applicable. It is important to note that Sedimentation Pond E is a relatively small structure, with maximum stocage capacity at the top of the embankment wall of only ].74 acre-feet of water. It should also be noted that the key provisions in TR-60 address design of the principal and emergency spillways. TR- 60 requires that the emergency spillway pass a calculated flow volume based on the peak flows from the 100-year precipitation event plus a portion (0.12 (PMP - Pt W)) peak Elow from the PMP event. A check of the design ca]culations for Sedimentation Pond E indicates that the emergency spillway, as designed, will safely pass the peak Eows from the 100-year storm event with 1 foot of freeboard. A copy of the SEDCAD runs for the 100-yeaz, 24-hour event have been included with the revised hydrologic design calculations for inclusion in Exhibit 2.05-E4.