Many areas in the country currently face the daunting task of dealing with aging water and wastewater infrastructure. As municipalities grapple with leaking pipelines and broken water mains, they are often additionally tasked with improving filtration and cleaning systems to meet quality standards for their communities.
Due to the multitude of issues our water and wastewater providers face, they are often met with the decision of whether to completely replace older infrastructure with new pipelines or to use more recently available technologies that do not require whole excavation of the old line. In this field, there are many different options, from pipe bursting methods to cured-in-place-pipe (CIPP). Primus Line stands as one of the most unique and convenient methods of trenchless rehabilitation of pressure pipelines both in common and more unique circumstances.
Much of Johnson County, Kansas, has its potable water infrastructure maintained by Water District #1 of Johnson County (WaterOne), a quasi-municipal water utility that prides itself on the quality of its water and its ability to repair and install pipes with its own construction teams. They were wrestling with a problem that plagues most water authorities: A leaking line that ran directly under a highway, an active rail line and, also, under a high use roadway. Maintenance on these lines can be challenging not only due to aging pipelines and corrosion, but also due to costs associated with permitting around railroad lines, public roads and thoroughfares, and other infrastructure. Due to operational time constraints, the project was required to be completed in the middle of winter, with temperatures on the jobsite consistently averaging below freezing.
WaterOne first became acquainted with the unique properties of Primus Line at a trade show for showcasing trenchless technologies and immediately recognized its potential not only in rehabilitating pipelines in unique situations, but also its capabilities as an emergency repair option. Primus Line simply needs to be pulled into the existing, damaged pipe with a winch, set to form with air pressure within minutes, and the two end connectors that anchor the pipe are installed on either end of the now-rehabilitated section of pipe. Thanks additionally to the installation and anchoring methods used in the installation of Primus Line, no resins or curing processes are used on the pipe, although in higher pressure situations a fast curing resin is used in the implementation of the end connectors that anchor the pipe. No contact is made between the resin and any part of the line, however. With these qualities, WaterOne decided to move forward with a project to take advantage of the capabilities of this trenchless technology.
In this case, a 24-in. potable water line was in need of rehabilitation but ran 1,890 ft under a freshly paved road, railroad crossing, and highway overpass. Not only that, but the line had a 90-degree bend, a 30-degree bend, and multiple 45-degree bends along its run, limiting rehabilitation options.
The Kevlar-reinforced flexible polyethylene pipe manufactured by Primus Line was the optimal solution for this project.
At least three bends in this line, including one at a 90-degree angle, were located directly beneath a freshly paved street and recently redone railroad crossing. The alternative option for repair was to dig and replace, increasing the cost of the project by $1 million. It would not only increase the price of the repairs due to the street excavations and permitting requirements, but it would also increase congestion and traffic in the area, adding an additional cost to local businesses and commuters.
The additional pits required for the removal and replacement of this pipe was not the only concern. Primus Line’s flexible, Kevlar-reinforced technology provided the required minimum operating pressure of 100 psi required for this now-20-in. potable water line navigating the sharp bends.
During the evaluation process for this project, the host pipe diameter of 24 in. was compared to the Primus Line 20-in. diameter pipe, the DN500, for hydraulic capacity. It was determined that Primus Line would maintain an adequate flow rate, with a C-Factor of 150, compared to the existing host pipe. The pipe owner determined that as long as the pipe met the expected pressure requirement of the existing line, it would be an acceptable solution for the repair of the pipe.
The flexibility of the liner allowed for the navigation of the 90-degree bend and additional smaller bends in this line, while the Kevlar weave of the liner was able to handle the required pressure the line would be under during operation: about 100 PSI.
Since no excavation was required for the bends under the roadway, the entrance and exit pits were located outside of high traffic areas, minimizing any impact to local traffic. The host pipe was inspected to check the condition for any issues that might impede the Primus installation process. Upon seeing the line was in good condition, the Primus Line was brought on site and inserted from the reel at an angle of 180-degrees, being pulled out of the exit pit at a 45-degree bend by a winch. The pull-in lasted about three hours.
After this, the patented connectors were installed to anchor the Kevlar line in the host pipe and reinstate the water line via an ANSI flange and spool piece. The Primus process was successfully completed by the expert workers of Water One and was finished in less than four days’ time.
With cost savings of $1 million, a short installation period of only four days, no additional permitting from local municipalities required, and a preservation of normal traffic conditions in a busy area with nearby Business Park, the choice was clear.
No other trenchless technology would have the ability to navigate these bends, maintain the required pressure, and be able to be installed in such a short time period entirely with the owner’s own construction personnel.