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999 <br /> 0 2 2000 <br /> u ran go <br /> SUN NYSIDE GOLD CORVOTIATIOWIT,20ivisiDon Of Mi Field Offi., <br /> nera/s a Geology <br /> AN ECIZO 33"COMPANY <br /> P.O. Box 177 * Silverton, CO 81433 DJE�jv <br /> Phone (970) 387-5533 Fax (970) 387-5310 <br /> P tj"04 1 C17 4_ft� <br /> C <br /> op <br /> 1 4. z <br /> September 27, 2000 <br /> Mr. Wally Erickson, Reclamation Specialist <br /> Division of Minerals and Geology <br /> Department of Natural Resources <br /> 484 Turner Drive, Bldg. F, Suite 101 <br /> Durango, CO. 81301 <br /> V/ <br /> RE: File No. M-77-378, San Juan County <br /> /R-23 <br /> rry Tunnel Bulkhead Concrete Mix Modification <br /> Submittal <br /> Dear Mr. Erickson: <br /> Sunnyside Gold Corporation (SGC), in TR-22, specified that the same concrete mix used <br /> for the American Tunnel bulkhead would be used for the outside Terry Tunnel bulkhead. <br /> This concrete mix contains both Type V cement and Class F flyash which is used for <br /> applications exposed to very severe sulfate conditions. Unfortunately, the market for <br /> Type V cement is very small and SGC's concrete supplier has been unable to secure a <br /> supply adequate for pouring the bulkhead. Because of this supply problem and SGC's <br /> specification for this concrete mix, SGC was unable to pour the bulkhead when scheduled <br /> and may experience an extended delay while a supply is secured. To prevent this from <br /> occurring, SGC submits this TR for modification of the mix design. While this <br /> modification does reduce the ability of concrete to resist very severe sulfate conditions, it <br /> will be adequate to resist severe sulfate conditions and more than adequate to resist the <br /> exposure conditions anticipated for the outside Terry Tunnel bulkhead. The reason for the <br /> different potential exposure conditions is that the American Tunnel bulkhead would be <br /> exposed to water in contact with a massive sulfide ore-body while the outside Terry <br /> Tunnel bulkhead will only be exposed to water in a cross-cut outside the ore-body. To- <br /> date the Sunnyside Mine pool does not classify as a very severe exposure condition (ie <br /> SO4>10,000 ppm) at a SO4 concentration of 2850 ppm with exposure to unlimited <br /> sulfide material. It is unlikely the Terry Tunnel near surface bulkhead will ever be <br /> exposed to severe sulfate conditions with limited source material for concentrating in the <br />