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INTEROFFICE MEMORANDUM <br />Date: 20 August 2013 <br />From: Marcia L. Talvitie, P.E. <br />To: Susan Burgmaier, Lead Specialist <br />Subject: Bowie No. 2 Mine — C- 1996 -083 <br />TR -80 — Subdrainage System for CMDA #3 <br />Adequacy Review — Geotechnical <br />As requested in your Email dated 31 July 2013, 1 have reviewed the application for TR -80 submitted by <br />J.E. Stover and Associates (Stover) on behalf of Bowie Resources, LLC (Bowie). With TR -80, Bowie <br />proposes to incorporate a subdrainage system into the design for Coal Mine Waste Disposal Area No. 3 <br />(CM DA #3). <br />Approved designs for CMDA #3 are found in Volume XI of the permit. Proposed new language has been <br />submitted, creating a new "Subdrainage System" section beginning on Page 6 of the Volume XI permit <br />text. The location and typical section of the proposed subdrainage system are shown on revised Map <br />No. 21 -1, Drainage Plans, Sheet 1 of 4. Installation of a subdrainage system was necessitated by the <br />discovery of a seep that has developed from the Fire Mountain Canal. The proposed subdrain will <br />intercept seepage from uphill of the pile, convey any collected flow beneath the entire pile, and daylight <br />at the pile's toe. <br />Subdrainage systems for coal mine waste piles are addressed in Rule 4.10.3 Water Control Measures. <br />Paragraph (1) of that rule requires that the system (a) intercept all ground water sources; (b) be <br />protected by an adequate filter; and (c) be covered so as to protect against the entrance of surface <br />water or leachate from the coal processing waste. Allowance is made in (1) for the use of alternative <br />specifications as described in 4.10.3(5). <br />In the revised text on Page 6, Stover indicates that the design of the rock drain will be an <br />alternative design in accordance with Rule 4.10.3(5). 1 do not see any obvious departures from <br />the criteria of (1), except perhaps that the proposed cover for the drain is one foot of "common <br />fill" rather than the impermeable fabric layer that is commonly seen. The application fails to <br />address the additional requirements of (5), specifically the "thorough analytical demonstration" <br />regarding applicable static safety factor, stability of the fill, and protection of the surface and <br />groundwater. I suggest that the applicant reconsider the requirements of (5) and provide the <br />appropriate analytical demonstrations, or withdraw the "alternative design" element. <br />In the first paragraph of the Subdrainage System section, on Page 6, the text indicates that the <br />drain will be about 100 feet wide near the seep. The thickness of the drain is inferred to be two <br />feet, based on the area (200 Sq.Ft.) given in the following paragraph. However, it is not clear <br />