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American Tunnel 1 ;head Construction Pai 3 July 12, 1995 <br /> the form. Inspection during filling demonstrated that the wire <br /> ties performed as required. The pipes did not deflect or displace <br /> during filling or when the concrete was vibrated alongside the <br /> pipes to achieve intimate contact of the concrete completely around <br /> the pipes. <br /> Any one of the two combination pipe joints and thrust collars <br /> or of the three combination water stops and thrust collars on the <br /> 12-inch nominal diameter Schedule 80 (Extra Strong) 316L Stainless <br /> Steel is capable of supporting the 72700 lb of thrust that will be <br /> applied if the maximum design of 670 psi is applied to the closed <br /> valve. In fact, just under four square inches of metal (3.826 in2) <br /> is required and each of the thinner water stops provide 15.02 <br /> square inches of thrust resisting metal. The nominal 1-inch <br /> diameter (0.957-inch inside diameter) Schedule 80 (Extra Strong) <br /> 316L Stainless Steel pressure sensing and water sampling pipe will <br /> develop 482 lbs of thrust at the maximum 670 psi design head. The <br /> four 3/8-inch thick combination water stops provide 1.549 in of <br /> metal, when only 0.025 in is required to resist the maximum <br /> thrust. The water stop on the bypass pipe closest to the air-side <br /> bulkhead is more than the specified minimum 6.5 feet from the <br /> downstream (air-side) bulkhead face. The design requirements <br /> detailed in the February 28, 1994 bypass pipe design calculations <br /> have been exceeded in every instance. <br /> The first Moran Car, containing approximately 6 cubic yards of <br /> concrete arrived at the concrete pump at 8:38 a.m. Thursday July 6, <br /> 1995. The car had been delayed by a computer problem at the batch <br /> plant. Filling of the form commenced at 10:07 a.m. , having been <br /> delayed by plugs in the slick line, similar to previous start up <br /> problems on other bulkheads. Filling of the form proceeded <br /> continuously, except for a three minute power outage, until the <br /> 22nd, and last, Moran Car arrived with a high water content batch <br /> that segregated in and plugged the fill line. The 22nd Moran Car <br /> had to be dumped, the pump hopper emptied, the slick line cleaned <br /> and another car brought in to complete filling the form. Filling <br /> of the form was completed at 4:02 a.m. , July 7, 1995. Final <br /> filling of the form was as hectic as usual. Filling was stopped <br /> after some timber snapping, some water bleeding through the 2-inch <br /> by 12-inch bulkhead boards, when Scott Warren observed the <br /> left-side angle brace pushing so hard against the rock that the <br /> rock under the brace started to spall. The pump pressure at <br /> termination of the pour was 350 psi. <br /> Approximately 130 cubic yards of concrete were injected into <br /> the American Tunnel Bulkhead form. Four concrete test samples were <br /> taken during the course of pumping from each Moran Car, except for <br /> number 22. Considering the volume of concrete involved, the <br /> filling of the American Tunnel Bulkhead went pretty smoothly. <br /> Only contact grouting of the bulkhead/rock interface, at the <br /> specified 100 psi to 500 psi pressure, needs to be completed. Of <br /> course the downstream form must be removed, a minimum of seven days <br />