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999 <br /> SUNNYSIDE GOLD CORPORATION <br /> AN ECHO 2"COMPANY <br /> P.O. Box 177 .Silverton, CO 81433 <br /> Phone (303) 387-5533 .Telecopy (303) 387-5310 <br /> March 7, 1994 <br /> Cnv1 cwe r� :.E.: <br /> 40 <br /> Allen Sorenson, Reclamation Specialist /jam <br /> Department of Natural Resources <br /> Division of Minerals and Geology <br /> 1313 Sherman Street, Room 215 <br /> Denver , CO 80203 <br /> RE: Technical Revision to TR-14, File No. M-7�/-378 <br /> Dear Mr . Sorenson: <br /> This letter is a Technical Revision submittal to modify bulkhead <br /> specifications and/or designs approved in TR-14 . These <br /> modifications are being requested to provide flexibility for <br /> construction logistics and system operation uncertainties. The <br /> specific changes being requested are listed and discussed below. <br /> 1) Change the B-Level Brenneman bulkhead design strength from <br /> 3000 psi to 2500 psi and adjust bulkhead construction <br /> specifications to maintain bulkhead strength requirements. <br /> The approved concrete mix design has zero slump which makes it <br /> extremely difficult to pump. From experience gained in <br /> construction of the F-Level Brenneman bulkhead, it will not be <br /> possible to pump the mix as specified the 1000 feet that is <br /> required on B-Level without adding slump (ie water ) to the <br /> mix. This will theoretically result in an overall strength <br /> loss. Based on the F-L Brenneman test cylinder breaks <br /> (attached) , it is probable that water could be added and still <br /> meet the 3000 psi bulkhead concrete strength requirements. <br /> Regardless, it would be prudent to construct for a lower <br /> design strength and accept any excess strength for increased <br /> durability. <br /> Based on the above, John F . Abel Jr . , P.E . was asked to <br /> redesign the bulkhead with 2500 psi as the design strength of <br /> the concrete. The modified design is attached for your <br /> review. The only change required would be to increase the <br /> amount of tension reinforcement (#10 @ 12 in. C-C from #6 @ 12 <br /> in. C-C) . While this is a significant increase in steel area <br /> provided, not all of this change is attributable to the <br /> proposed concrete strength change . The proposed concrete <br /> design strength change required a change from #6 @ 12 in. C-C <br /> to #6 @ 9 in. C-C. <br />