The Frontrunner Commuter Rail
This large-scale project presented several piping challenges.
A previous 30” irrigation line, 45 feet under a freeway embankment, was installed by another company with an angle that made future repairs nearly impossible. The contractor called upon Nix Construction to dig into the embankment, cut the steel casing, disconnect the waterline, and re-lay it to connecting lines in order to eliminate the troublesome angle.
Construction was complicated by a high groundwater table, two sets of busy railroad tracks, the 45-foot embankment traveled daily by large trucks, and ongoing construction of the new light-rail system almost directly over the site. Nix had one shot to successfully complete the project with an exact alignment of the new pipeline. Open cutting to resolve any problems would not be possible.
According to Chief Operations Officer Jon Nix, in the world of trenchless construction, you have to choose “the right horse for the course.” To solve this complicated construction project, the right horse combined three distinct technologies. From the new tie-in position to the angle, Nix hit the mark dead on using pilot tube microtunneling. Next, the new 36” steel casing was attached to the pilot tubes and rammed in with a TT Technologies 18” Goliath pipe hammer. The pilot tubes kept the casing on line and grade as the hammer pounded it beneath the rails. Lastly, a Robbins auger bore machine cleaned out the casing. All this was accomplished while keeping the groundwater under control amid late spring snowstorms.
Prior to this project, this combination of methods had only been used three times in the U.S.