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January 24, 2013 <br />To: Brock Bowles <br />From: Susan Burgmaier <br />Re: North Thompson Creek Mine (Permit No. C- 1981 -025) <br />Technical Revision No. 27 (TR -27) <br />Request for Assistance - Adequacy Review <br />Per your request, I have reviewed MINREC's technical revision (TR -27) application for <br />the North Thompson Creek Mine, and have the following comments and questions for <br />the operator: <br />1. Revised page 4 -iii indicates that Ditch B, the eastern collection ditch into Pond P- <br />9, will occasionally be used to convey water from Pond P -9 to a small area for <br />irrigation purposes. When the primary spillway for P -9 is blocked to utilize Ditch <br />B, the ditch will essentially function as a spillway. As such, it will need to be <br />designed according to standard engineering design procedures for discharge <br />structures and the design information must be submitted to and approved by the <br />Division. <br />a. Please provide design information for the proposed Ditch B spillway <br />to satisfy the requirements of Rules 4.05.6(3)(c), 4.05.6(5), 4.05.7, and <br />4.05.9(2) for spillway designs. <br />b. Please revise the text on page 4 -113:2 to clarify the purpose of Ditch B. <br />C. Please revise the Ditch B calculations on page 1 of the Addendum to <br />Appendix 4 -113 to clarify the purpose of Ditch B. <br />2. Rule 4.05.2(8) requires discharges from underground mines to comply with all <br />State laws and regulations. The currently approved Colorado Discharge Permit <br />System (CDPS) permit issued by the Water Quality Division of the Colorado <br />Department of Health and Environment (WQCD) allows for discharge from pond <br />P -9 at outfall 001A. MINREC's proposal to discharge water through Ditch B will <br />bypass outfall 001A. Before the Division can approve rerouting of discharge <br />through Ditch B, MINREC will need to provide a revised CDPS permit that allows <br />for the additional discharge point or clearly specifies that the approved outfall <br />may be bypassed. Please provide documentation of WQCD approval for <br />discharge from the Ditch B outfall. <br />3. On proposed page 4 -iv, MINREC indicates that water rights should be adequate <br />to store water in the refuse pond, but does not address water rights as they <br />pertain to the proposed irrigation use of water overflowing from the east ditch. <br />Please provide, in accordance with Rule 2.05.6(3)(a)(ii), documentation <br />