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Sunnyside Gold Corp. Page 5 March 10, 1993 <br /> The bulkhead designs include shrinkage and temperature steel <br /> for all water-side bulkhead faces. In all cases the shrinkage and <br /> temperature steel is two-way, horizontal and vertical, #6 bars on <br /> 12-inch centers, in accordance with ACI 318-89, Section 7. 12 . 2 .2 . <br /> The basic concrete mix is 1:2.5:3.5, cement, sand, aggregate. <br /> A water-cement ratio of 0.45 is recommended for the sulfate <br /> resistant Type V cement, 5.4 bags per yd3, to provide maximum <br /> sulfate resistance (ACI 318-89, Section 4 .2 . 1) . This high sand <br /> content mix is recommended to enhance pumpability and to minimize <br /> voids and "honey combing" of the placed concrete. Easily pumpable <br /> concrete is required because it will not be possible to vibrate the <br /> concrete into the bulkhead forms. Fly ash (pozzolan) in the amount <br /> of 16 percent of the weight of the cement is recommended to further <br /> improve pumpability, increase slump and decrease permeability <br /> (Troxell et al, 1968) . The Standard Handbook for Civil Engineers <br /> (Merritt, 1983 , Table 8-4) indicates that a maximum aggregate size <br /> of 2 inches can be used. However, it is recommended that 3/4-inch <br /> maximum aggregate size be used, again to enhance pumpability and <br /> minimize voids, segregation and "honey combing" . The mean concrete <br /> strength, f'CR, used in determining the proportions of aggregate, <br /> cement and water is 4990 psi (ACI 318-89, Sections 5. 3 . 2. 2 and <br /> Merritt, 1983, p 5-5) . This, f'., should yield a concrete strength <br /> of 3000 psi, or higher, under actual working conditions. This high <br /> mean strength is necessary in the absence of compression test <br /> cylinder data. It should be possible to adjust the mix proportions <br /> when compression test data becomes available. <br /> The planned bulkhead placement sequence is from the highest to <br /> the lowest, from the uppermost B-Level Brenneman/Sunnyside <br /> connection bulkhead down to the lowest American Tunnel bulkhead. <br /> Bulkheading the Terry Tunnel will temporarily transfer additional <br /> mine drainage water to the American Tunnel. The anticipated <br /> maximum water quantity that would have to pass through the American <br /> Tunnel bulkhead during spring runoff is 2200 gpm (4 .9 cfs) . The <br /> nominal 12-inch diameter pipe specified will pass 2500 gpm (5. 6 <br /> cfs) , with 5-foot of head behind the upstream coffer dam. During <br /> the planned construction period the anticipated maximum flow <br /> through the temporary diversion pipe should be 1200 gpm (2 . 7 cfs) . <br /> The thrust on the diversion pipe will be resisted by headed <br /> anchor shear studs (1/2-inch diameter by 2-inch headed studs) , <br /> welded to the pipe. Two studs are recommended every foot along the <br /> pipe, alternating 90 degrees of rotation along the pipe. This <br /> design provides 46 studs to resist the thrust when the full 1550 <br /> feet of potential head is applied. This provides a design factor <br /> of safety of 1. 60 and ignores skin friction between the pipe and <br /> the concrete and the shear strength of the pipe flanges. <br /> Single continuous bars are specified for all curtain steel. <br /> However, splicing can be employed if sufficient lap is provided to <br /> develop full bar strength in tension. The overlap development <br /> length recommended for the #10 bars is 82 inches. This means, in <br /> effect, that each overlapped bar would have to be 41 inches longer <br /> and weigh approximately 15 lbs more than a single bar or 30 lbs <br />