The qualities of polyethylene pipe are piquing the interest of more civil engineers of potable water systems in North America.
The telecommunications and utility industries have long used PE pipe to protect fiber optic cables and deliver natural gas, but use of the material for drinking water systems is still trickling slowly toward acceptance in some places.
In Michigan, Los Angeles-based JM Eagle's offer to replace all lead service lines (LSLs) in Flint, where toxic levels of lead leached from damaged pipes, with free PE pipe prompted not only a study of three kinds of pipe materials — PE, cross-linked PE (PEX) and copper — but a lunch-and-learn session about PE pipe with engineers.
Dustin Langston, an engineer at WL Plastics Corp., which is based in Fort Worth, Texas, said in a telephone interview that his presentation went over the allotted hour with no objections.
“The information was taken well; they had a lot of great questions. It was a very productive meeting,” he said.
With estimated annual sales of $2.45 billion and yearly pipe sales of $340 million, respectively, JM Eagle and WL Plastics are the first- and 11th-ranked manufacturers of plastic pipe, profiles and tubing in North America, according to Plastics News' latest ranking. Their overall PE pipe sales are down in the last year because of a 40 percent drop in demand from the oil and gas gathering industry, according to the Plastics Pipe Institute (PPI), a trade association based in Dallas. However, potable applications show big promise as U.S. cities look to get the lead out of their systems and make some $1 trillion of upgrades over the next 25 years.
Langston said about 15 people attended the meeting at the Flint office of Rowe Professional Services and a handful of others Skyped in. Rowe handled engineering work for Flint until June 30 — the city plans to hire a staff engineer now — but the firm will be solicited for future work, the city said in a statement.
The presentation focused on high density PE pipe and installation methods. Rowe's engineers' main experience with HDPE to date is using it for horizontal directional drilling (HDD) under rivers, Langston said, adding he got a lot of wide eyes when he talked about the installation method of pipe bursting. Few of the attendees had heard of the technology before.
Burst onto the scene
A trenchless method for replacing buried pipelines, pipe bursting was first used in the 1970s in the United Kingdom. The process involves digging roughly 3-foot-by-3-foot entry and exit pits by the house and street, where the service line meets the distribution line or water main. A cone-shaped drilling head with a slightly larger diameter than the old pipe is inserted into an opening. The front end of the bursting head is attached to a pulling cable and the back end is connected to new PE pipe. As the bursting head is pulled through, it breaks the existing pipe into pieces and simultaneously expands the diameter of the cavity for the new pipe.
The old pipe pieces just stay in the ground. Experienced crews can replace three to four service lines a day at 75 percent of the cost of cut-and-bury installation methods, Langston said.
“You take 25 percent off the price,” he added. “You don't have to dig up people's lawns or take out people's driveways. You save money on having to replace those things and you're not disturbing the community. In civil engineering, there's a new aspect that's rarely accounted for and that's social interference. We always talk about cost but what isn't measurable cost wise are the calls and complaints to city offices about construction, noise, debris and dug-up yards. A lot of things are suddenly avoided using trenchless technologies.”
Livonia, Mich., used HDPE pipe from Charter Plastics Inc., which is the No. 77 ranked PPT extruder, to replace 27,000 feet of cracking, leaking iron pipes from April through October 2008. The Titusville, Pa.-based company has estimated sales of $35 million a year.
Livonia reportedly saved $200,000 on Charter's pipe material alone compared to ductile iron and then used pipe bursting to install it. Todd Zilinick, Livonia's chief engineer, still tells his colleagues about the social and environmental advantages of PE pipe.
“One of the greatest benefits of high density polyethylene pipe is it's easy to install, it's less disruptive … and it saves trees,” Zilincik said in a May 2016 testimonial for the Alliance for PE Pipe, which is based in Tulsa, Okla., and promotes the use of HDPE pipe for municipal water systems in the U.S. and Canada as “the responsible infrastructure choice.”
HDPE pipe is joined by heat fusing above grade, which essentially creates a single pipeline free of leaks that can be miles long.
“It's completely welded together,” Langston said. “It won't leak, corrode or rust and it's durable with a 100-year service life. It's also completely inert. Nothing leaches out of polyethylene pipe. If you look at all the food packaging, whether it is milk, soda, water bottles or food, the great majority of that is PE.”
Out of the trench