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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY ?/? ?,(f <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />COLORADO <br />Denver, Colorado 80203 D I V I S I ON OF <br />Phone: (303) 866-3567 RECLAMATION <br />FAX: (303) 832-8106 MINING <br /> <br />? <br />SAFETY <br />23 May 2011 <br /> John W. Hickenlooper <br /> Governor <br />Mr. Randy Whicker Mike King <br />Health Physicist / RSO Executive Director <br />Cotter Corporation Loretta E. Pineda <br />Director <br />P.O. Box 1750 <br />Canon City, CO 81215 <br />J <br />Re: Schwartzwalder Mine, Permit No. M-1977-300, Technical Revision TR-18 Adequacy <br />Review <br />Dear Mr. Whicker: <br />The Division of Reclamation, Mining, & Safety (Division) has conducted a preliminary review <br />of Technical Revision JR) Request TR-18 and we have identified several issues that must be <br />addressed before we can approve the TR. The Division engineering staff is also reviewing the <br />document and may have additional adequacy issues that will be conveyed under separate cover at <br />a later date. <br />1) Please provide the proposed thickness of the 42-inch diameter welded steel pipe. <br />2) Indicate whether there will be an access road along the length of the pipeline for maintenance. <br />3) Describe how data collection efforts in the alluvium will be affected and modified during <br />times that Ralston Creek flow exceeds the design criteria of 100 cfs. <br />4) Will the cleanup activities mentioned in Section 3.1 be done under existing TR-14 or under a <br />future TR? <br />5) Approximately how much earth will have to be excavated to allow room for installation of the <br />cutoff walls? What will be done with the earth removed? <br />6) What are the approximate dimensions of the cutoff walls (length, height, width)? <br />7) Will the cutoff wall, and any other concrete or steel structures other than the 4,000 ft long <br />pipe, be removed at the conclusion of the project? <br />8) Understanding that possible irrigation requirements are not yet finalized, please provide the <br />anticipated rates of irrigation water application and anticipated time periods of application. <br />9) What is the anticipated time duration of the post-operational biological monitoring period, <br />presented in Section 3.2, for stream habitat restoration? <br />Office of Office of <br />Mined Land Reclamation Denver • Grand )unction • Durango Active and Inactive Mines