1997-08-25_REVISION - M1977493 (11)

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III IIIIIIIIIIIIIIII 999 © CLIMAX MOLYBDENUM COMPANY COLORADO OPERATIONS A Division of Cyprus Climax Metals Co Climax Mine Hwy.91 Climax,Colorado 80249 (719)486-2150 Fax.(719)486-2251 August22, 1997 R>_ �/_�E� EQ Certified Mail No. P 522 831 040 q Mr. Allen Sorenson AUG 2`5 19971 Division of Minerals and Geology Division)u, ,viinerals&Geology 1313 Sherman Street, Room 215 9Y Denver, CO 80203 RE: Design for pipeline extension at existing Environmental Protection Facility - 5- Dam Seep Pumpback Station Return Line - TR-07 Environmental Protection Plan, Permit No. M-77-493 Dear Mr. Sorenson: Attached to this letter is the design for the extension of the 5-Dam seep return line, an existing Environmental Protection Facility. The Climax Molybdenum Company (CMC) is constructing this extension to improve water treatment in Mayflower Tailing Pond. While the extension is specifically aimed at maintaining and improving water treatment under the Climax NPDES Permit (CO-0000248), CMC is informing DMG of this improvement. The extension does not modify the existing pump capabilities, ultimate dispensation, or operational systems empoyed to manage 5-Dam seep waters The current line returning 5-Dam seep waters to the Mayflower Treatment Pond terminates at the north end of the pond at a point furthest from the input of milk-of-lime treated waters. The 5-Dam seep waters are of a quality that can impair discharge water quality under low flow conditions experienced in late winter. The extension will deliver 5- Dam seep waters to the toe of 3-Dam where seep water from 3-Dam, waters exiting the Tenmile Tunnel, and waters from the Lime Plant are delivered as a single treated stream into Mayflower Tailing Pond. The extension allows the input of a single wastewater stream into the treatment pond when the Clinton Cutout is not in operation and will effectively eliminate short circuiting of the treatment system by 5-Dam seep water. In addition, the rerouted pipeline will increase residence time and pond settling capability. The extension has been designed for maximum utility and operational flexibility in wastewater treatment at Mayflower Pond. The placement of the line will see the addition of two cutout valves allowing backflow of milk-of-lime to the north end of the treatment pond. The entire pond may therefore be treated using operational control of the pumps at 5-Dam and lime delivery to the toe of 3-Dam. Routing of the line considers the current capability of the pumps at 5-Dam to deliver water to the toe of 3-Dam. Configuration of the surge suppression system is under final evaluation and detailed engineering.