Industry Trends: Finding “The Perfect Pipe”

In early 2017, the Southwest Wet-Weather Control Facility project, completed with RJN Group, Inc. as the primary engineering consultant; the City of Elmhurst as the managing agency; and Boller Construction, Inc. and Archon Construction Company as the contractors, earned recognition as a Public Works Project of the Year in the Structural: $5 Million to < $25 Million Category of the Suburban Branch of the APWA Professional Awards.

The Southwest Wet-Weather Control Facility (SWWCF), serving the southwest area of the City of Elmhurst, is a sophisticated wet-weather flow control system centered around a dry- and wet-weather pumping station that directs flow based on measured flow levels to a dry-weather force main, a wet-weather force main, and a 2.2 million gallon (MG) storage tank located at the City’s Water Reclamation Facility (WRF). The primary purpose of the SWWCF is to provide protection to property owners through additional wet-weather capacity, mitigating recurring basement backup issues.

As part of this project, RJN engineers needed to design a wet-weather force main. After assessing the area where this force main would be built, RJN engineers concluded that the material chosen for the pipe needed to be as light as possible with a smaller profile that would result in less excess material being reamed.  After initially considering fusible PVC, RJN engineers determined that a restrained joint PVC pipe would be the perfect pipe for this installation.

Unfortunately, when this design was first developed, North American Pipe Corporation didn’t make the Certa-Lok PVC pressure pipe in an 18-inch size, which was required for this particular force main. RJN reached out to the manufacturer to request this size be made available, but the manufacturer said they had no plans to place an 18-inch Certa-Lok PVC pressure pipe into production.

In a timely change of events, North American Pipe Corporation announced shortly before the SWWCF project was bid that they would be manufacturing the 18-inch Certa-Lok restrained joint pipe, just in time for construction. This made the Southwest Wet-Weather Control Facility in Elmhurst the first project ever to receive the 18-inch Certa-Lok restrained joint pipe from the factory.

DID YOU KNOW?


C900/RJ Certa-Lok PVC Pressure Pipe is North American Pipe Corporation’s unique coupled, restrained joint system for potable water, wastewater, sewer force main, and reclaimed water applications, usually with trenchless technologies. It offers robust tensile strength to enable pulling multiple segments underground. The low profile coupling makes assembly quick and easy while maintaining leak-free results. Precision-machined grooves on the pipe and in the coupling align to allow the insertion of a spline that locks the pipes together. A flexible elastomeric seal, or gasket, in the coupling provides a hydraulic seal. North American Pipe Corp. produces Certa-Lok restrained joint pipe of the type used on RJN’s award-winning Southwest Wet-Weather Control Facility project in Elmhurst with sizes from 4” to 24”.

Sources: North American Pipe Corporation and Trenchless Technology Magazine

Despite there being many possible pipe materials to use with directional drilling installations, sometimes the search for “the perfect pipe” to install during engineering design projects can lead to the need for a very specific material and pipe type. The use of a PVC material as force main for the SWWCF installation was predicated on the need for a lighter, smaller-profile pipe to minimize reaming diameter in ground with minimal bearing strength.  In addition, the limited space in some locations required a pipe that would not need fusing. The 18-inch Certa-Lok restrained joint pipe was the ideal pipe—“the perfect pipe”—for this application, and its entry into the market just as this project was being bid enabled the project to be undertaken with minimal construction modifications.

Shown below is a short video of this pipe’s installation.

To learn more about this force main’s design, attend the presentation, “Large Diameter Restrained Joint PVC Pipe Helps Chicago Suburb Get Relief from Sewer Backups,” presented by RJN Senior Project Manager Cathy Morley, P.E., at the North American Society for Trenchless Technology (NASTT) 2017 No-Dig Show in Washington, D.C. from April 9 to April 13.  Keep an eye on our website in the coming weeks for more details about Cathy’s presentation and presentations by other RJN engineers at NASTT’s 2017 No-Dig Show.

The pipe was pre-assembled in 200-foot strings before pulling, instead of cartridge loading the pipe, to enable the pull-back time to be minimized and not risk losing the borehole.