The city of Lincoln, Neb., is fast outgrowing its 880 miles of sanitary sewers. To remedy this situation, the Lincoln Wastewater System (LWWS) is upgrading its wastewater collection system.
That's a lot of pipe.
The LWWS considered only pressure-rated products for its new gravity sewer line, which as the community expands will be reconfigured to operate as a low-head force main. Specified pipe options included:
- Centrifugally cast, fiberglass-reinforced, polymer mortar pipe (CCFRPM)
- Prestressed concrete cylinder pipe (PCCP)
- Solid-wall, high-density polyethylene pipe (SW-HDPE)
- AWWA C-905 standard specification for polyvinyl chloride water transmission pipe (C-905 PVC).
Installation contractor Roloff Construction Co. of Omaha, Neb., chose CCFRPM because of its overall economic advantages (i.e., ease of handling, Tee-based manhole construction), 20-foot joint lengths, and simple gasket sealed joint.
“On a direct bury project like this one, we needed a simple slip joint,” says Roloff project superintendent Monty Habrock.
Once the first 600-foot line was installed from manhole to manhole, the pipe was tested. “The air test held so well that we decided to plug the manholes and test up to 2000 linear feet at a time, and it never dropped a pound,” says Habrock.
The entire line was then pressure-tested to 6 psi for two hours without a single leak or pressure drop.
The pipe's FWC coupling can be used for both gravity and pressure installations, making it an ideal solution for meeting Lincoln's current and long-term needs. The ‘gravity' couplings easily withstand 50-psi internal pressure, and a similar coupling design can be used in pressure systems operating up to 250 psi. And with a projected service life of 100 years, the pipes themselves should meet the challenge as well.
Read the main article, "Two for One"