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~~ ~ • iii iiiiiir«iiiiiii ~~ Cripple Creek & Victor Gold Mining Company 999 A Joint Venture -Pikes Peak Mining Company, Manager (1 ~ 7 Operations Oilice Englewood Office [®~7tEyN~1'/ PO. Box 191, 2755 State Highway 67 5251 DTC Parkway, Sui[e 700, Englewood Victor, Colorado 80860 Colorado 80111 (719) 689-2977 • FAX (719) 689-3254 (303} 889-0700 • FAX (303) 889-0707 SENT BY FACSIMILE -COPY FOLLOWS BY MAIL September 2, 1994 Mr. Berhan Keffelew Environmental Protection Specialist Colorado Department of Natural Resources Division of Mines and Geology f Office of Mined Land Reclamation 1313 Sherman Street, Room 215 Denver, Colorado 80203 Reference: Cresson Project: Permit Number M-80-244: Commitment Number "33" (Soecifications) -Installation of Leak Collection Riser Pipes On Top Of Liner. Dear Mr. Keffelew: Pursuant to the approved application for Amendment Number 6 to the subject permit and Cripple Creek & Victor Gold Mining Company's ("CC&V") commitment number "33" thereto, the following request for approval is submitted to the Office of Mined Land Reclamation by CC&V. Commitment number 33 reads: 33. "Design and specification changes, as defrned in Section 6.05 of the CQA plan and technical specifications, shall only be made with written agreement of the OMLR. " As a result of more detailed examination of the planned installation of the leak detection riser above the Regnant solution storage area, it has been determined that the "specifications" for installation should be changed to facilitate construction. The configuration shown on the construction drawings (see Drawing u~m6er 16, Detail "E") will be difficult to construct once the lines leave the pregnant solution storage area because it would require a trench that would run beneath the leak detection trenches. Construction according to that design would be further complicated by the fact that the risers would extend through the anchor trench at the 9360 level. Revised detail drawings are provided as Attachment 1. The proposed change in the configuration described here would maintain the risers on top of the geosynthetic liner. This will offer an improved level of containment. However, because the re- design does not include a trench, the wall thickness of the two riser pipes has been increased from a SDR 17 (0.75 inch) to a SDR 11 (1.273 inch). To accommodate the increased wall thickness, the outside diameter of the leak collection riser pipes has been increased to 14 inches.