Tioga dewatered the site and constructed a load bearing bottom in the existing structure. Since the water runs through the structure into the lake, it is an outlet-controlled culvert, so coffer dams were installed at both ends of the construction area in order to keep it dry. Bypass pumping from the inlet end was done using discharge hoses running through the barrel.
Tioga welded and pushed the liner segments into place. The work began at the outlet end by welding and pushing into place 6 of the 174” X 72” liner sections. The bevel configurations were designed so the welds on the bottom of the sections could be welded from inside the sections, to eliminating the need for welders having to get underneath them. The tops and sides were welded on the outside.
To manipulate the bend, a 174” X 72” X 4’-7 1/2”, 20.44° Elbow section was fed in from the inlet end. The Elbow, which was fabricated at the plant, was designed to be completely welded from inside of the liner where it adjoined the straight run that was fed from the outlet. The other end of the elbow was welded to the last 10’ section, that was pushed into place form the inlet end. These pieces were designed, fabricated, and installed with great care, to insure they would match up with the 57’ run, and align into the correct position within the existing structure.
InfraSteel engineers determined that welding the 234” X 72” reducing inlet piece, to a 20.44°mitered section, allowed parallel alignment of the inlet and outlet ends, and perpendicular alignment with the main barrel, without requiring an otherwise difficult mitered field weld. There were also structural design issues to overcome after load calculations showed that early reducer designs did not meet HL 93 loading requirements.
Additionally, both of the ends were shipped with Toe Plates that were tied into poured Cut-Off Walls. Grout was then pumped into the annular space through 2” grout ports that were manufactured into the liner and positioned along the tops and sides of the InfraSteel liner.
Tioga successfully completed the installation without traffic interruption, while maintaining the structures aesthetic qualities.