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Pipe Reaming, Restrained-Joint PVC Pipe Helps Colorado Municipality Complete Challenging Sewer Line Replacement
The design team explored several trenchless methods, eventually narrowing its choices down to two -- static pipe bursting and pipe reaming. Pipe reaming was recommended by a contractor the city had previously worked with and, due to the obstacles presented by the project, it soon emerged as the frontrunner.
“Pipe reaming was the more feasible choice, due to some concerns we had about pipe bursting in this application,” Saye says. “The commercial buildings were cinder-block construction and we were worried that bursting might produce strong enough tremors to crack or crumble their walls. We knew that reaming would work better in this situation.”
Pipe reaming is similar to static pipe bursting in that the host pipe is split by a cutting head and its fragments removed to allow the new pipe to be pulled into the same location as its predecessor. Pipe bursting disperses the host pipe fragments out into the surrounding soil. In pipe reaming applications, however, the fragments are ground more finely and mixed with bentonite drilling fluid to create a slurry which is evacuated through the manholes. The resulting pressure relief prevents any damage to nearby fragile structures or surface paving during the installation process.
Connell Resources subcontracted the pipe reaming to Temple Construction Company LLC of Fort Collins, which licensed the InneReam pipe replacement system from Nowak Pipe Reaming Inc., for the job. The plan was to upsize the sewer line to a uniform 12-inch diameter from its initial mix of eight- and 10-inch diameter pipe to provide better sewer service to the growing neighborhood. As for pipe material, the city preferred restrained-joint PVC, as PVC is already prevalent in the Fort Collins water and sewer infrastructure. It accepted Temple Construction’s recommendation of CertaFlo Greenline, a high-strength integral-bell PVC pipe from North American Specialty Products featuring the patented Certa-Lok restrained joint system. The product is available in 10-foot lengths, as well as standard 20-foot lengths, allowing smaller and more economical construction pit sizes, and its light green color also makes it easier to see during camera inspection of sewers.