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TWENTYMILE COAL COMPANY - FOIDEL CREEK MINE <br />TECHNICAL REVISION TR09-69 <br />6RT THICKENER UNDERFLOW PIPELINE AND BOREHOLE <br />TECHNICAL ADEQUACY RESPONSES (10/09) <br />1. Runoff from a portion of the pipeline disturbance, all of the borehole pad and light-use road <br />disturbance will not report to a sediment pond Although TCC included these areas in the <br />inventory of Small Area Exemptions (revised page 205-84.5) and indicated that Alternative <br />Sediment Control measures, straw wattles, vegetative filters, or berms will be used, the Division <br />did not find any demonstration that the Alternative Sediment Control measures are adequate for <br />the predicted runoff. Please provide additional detail that the Alternative Sediment Control <br />measures are adequate for the expected runoff from the proposed disturbances. <br />Response: In reality, of the approximately 8,000 of temporary pipeline disturbance, a maximum of <br />approximately 500 feet would be disturbed at any given time, since pipeline excavation, pipe <br />placement, and backfilling of the pipeline trench will occur as a progressive cycle along the length of <br />the pipeline. Given the location of the pipeline alignment, and the fact that much of the selected <br />alignment has been previously disturbed, approximately 1,750 feet of the pipeline disturbance will <br />drain to existing Sedimentation Pond E, approximately 1,200 feet (north of Warehouse Facility) will <br />drain to either Sedimentation Pond E or F, approximately 1,750 feet will drain to Sedimentation Pond <br />F, and 800 feet will drain to Sedimentation Pond G. Runoff and sediment from these areas, as well as <br />the remaining 2,500 feet of pipeline disturbance and the borehole pad and road, will still be controlled <br />using appropriate ASC's. <br />Given that the pipeline disturbance will be temporary and localized, and that the portion of the pipeline <br />disturbance not controlled by existing drainage and sediment control systems will be separated from <br />the receiving drainage by the existing raised railroad bed, a demonstration that the proposed ASC's <br />will adequately control drainage for the pipeline disturbance should not be necessary. TCC has, <br />however, developed a SEDCAD demonstration for the borehole pad and road demonstrating the <br />adequacy of the proposed ASC's to control runoff and sediment for this area. This demonstration <br />accompanies these responses for insertion in Exhibit 49S. <br />2. 4.05.18, Stream Buffer Zones TCC has requested a variance from disturbance less than 100 <br />feet from Foidel Creek. TCC proposes to implement Alternative Sediment Control measures to <br />minimize impacts to Foidel Creep Please provide additional detail regarding placement, <br />location, and type of control measures to be implemented before the construction activity and <br />after construction is completed to assure Rule 4.05.18(1)(a) and (c) are met. <br />Response: The text discussion on page 2.05-84.5 has been reviewed and revised to provide additional <br />details re: protection of Foidel Creek. This supplemental text, along with the SEDCAD demonstration <br />provided in response to Comment 1, should adequately address compliance with Rule 4.05.18(a) and <br />(c) <br />3. Revised page 2.05-32.1 has lost text previously approved during MR238 (page revised date <br />06126109). The reference to the "dedicated propane tank for the Washplant H heaters" was <br />eliminated from TCC's TR69 revised page 2.05-32.1. These heaters exist on the mine surface, so <br />the text needs to be retained. Please revise this page to retain previously approved text. <br />Response: The referenced page has been reviewed and revised to include the deleted text. Copies of <br />the revised page(s) accompany these responses for replacement in the PAP.