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American Tunnel Bulkhead <br />Construction Certification Report <br />Page 2 <br />Alternative designs were submitted for approval in TR -16 which <br />included different pipe types and seep collars to replace the <br />shear studs. <br />The selected design for construction was placement of a 12" <br />diameter Schedule XH 80S 316L SS pipe fitted with seep /thrust <br />collars. Only one collar was required. It was to be 18.75" <br />in diameter, 1/2" thick and placed at least 6.5 feet from the <br />downstream face (air side) to transfer loading to the rib and <br />prevent seepage along the pipe- concrete contact. <br />Actual construction consisted of three seep /thrust collars and <br />two flanged connections that also would serve the same purpose <br />within the bulkhead. All of which were placed greater than <br />6.5 feet from the downstream face. The seep /thrust collars <br />are 1/2" thick and are 6" greater in diameter than the pipe as <br />specified for design. The flange connections exceed these <br />dimensions. The available resistance to thrust failure and <br />seepage along the pipe is many times greater than design <br />specifications. Attached are material mill sheets for various <br />components of the piping installation. <br />The placement design called for pipe supports at 5 foot <br />intervals to support the pipe during placement of concrete. <br />This design was for standard weight pipe (Schedule 40) and <br />very conservative loading assumptions that could not occur <br />with good construction practices. <br />The actual C -C support spacing varied in the vicinity of 7 <br />feet with the longest clear span being 5 foot 10 inches. SS <br />cable anchors held the pipe at each support pillar. This <br />support was more than adequate for the construction procedures <br />used (ie filling under and around the pipe before filling on <br />top of the pipe). This filling procedure was photographed, <br />videotaped and observed by myself and John Abel Jr., the <br />design engineer (report attached) as agreed to during the DMG <br />pre -pour inspection. <br />The 1" diameter pressure observation pipe was specified to be <br />a "standard weight, Schedule 40" pipe with standard threaded <br />couplings. The installed observation pipe was 1" diameter, <br />Schedule 80 316L SS pipe fitted with four 3/8" thick seep <br />collars, 4" in diameter larger than the pipe in addition to <br />two Schedule 80 316L SS threaded couplings. This pipe was <br />anchored with SS cable to the ribs and back. These supports <br />were adequate to hold the pipe in place while the form was <br />being filled with concrete. <br />