An Introduction to Pipe Bursting

If you’re considering adding pipe bursting equipment to help with your onsite work, here’s what you need to know

An Introduction to Pipe Bursting

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When your business is growing and you’re thinking about ways to diversify your services, there might be one thing you’ve overlooked.

Adding pipe bursting to your repertoire is worth exploring. Pipe bursting offers many advantages compared to opencut installations. First and foremost, the new pipe follows the path of the host pipe, so there’s rarely a problem with hitting any other buried utilities. Disruption to roads, yards and other surfaces is also greatly minimized because excavation is only required for entry and exit pits.  

Pipe bursting also offers the ability to upsize pipes for additional flow capacity, sometimes up to five times larger than the host pipe’s diameter. 

The three owners of Ken-way Excavating found their specialty in pipe bursting to replace existing septic service lines. 

Getting the job done underground saves on fuel consumption over using traditional excavation, extending the work season in their frosty territory around Cedar Rapids, Iowa, and making customers happy by limiting the mess left behind by trench work. Charlie Fisher, who owns Ken-way Excavating with brothers Dan and Pat Zamastil, saw the technology as popular in other parts of the country and wanted to bring its advantages to Iowa. 

“I came home to Iowa from Denver, and there were sewer companies doing it there on a daily basis,” he says. Although he had not seen the technique used for onsite installations, he realized that the pipe between a home and a tank was no different than the lateral from a home to a sewer collection main. 

Two months into the partners’ ownership of Ken-way Excavating in March 2010, they purchased pipe bursting equipment, and it is often employed in the up to 30 onsite systems they install annually. The work ranges from simple gravity systems, perhaps with a sand filter, to those utilizing Ecoflo Biofilters (Premier Tech Aqua) for more limiting sites.

Know your machines

There are two main types of pipe bursting machines — static and pneumatic. Pneumatic machines use a hammer in conjunction with a constant tension winch, while static machines use high-tonnage static pull.  

Static machines can be used for all types of jobs, while pneumatic machines work more quickly but cannot be used in potable water systems since the hammer exhausts liquefied petroleum products into the pipe being installed and would find its way into the water system, says Kent Westendorf of HammerHead Trenchless. Pneumatic systems also have a footprint 50 percent smaller than static systems, which means crews need to do less excavation — a plus for many contractors.

“You need to decide between the two which one will work better for your project,” Westendorf says. “A lot of contractors like the advantages of the pneumatic machines, but then find out it might not work the best for every job they have.”  

Static and pneumatic pipe bursting machines come in a variety of sizes and can handle pipes ranging in size from 4 to 24 inches in diameter, even larger in some cases. The equipment should always be sized to install a pipe of the same size or one size larger. 

“Size is related to power and choosing the right power is related to the pipe size,” says Brian Kelly, president of Pow-r Mole Trenchless Solutions in Lancaster, New York. “The physical footprint can be especially important on certain jobs, especially if the site is crowded. You need to have enough room for the selected machine.”

Gaining experience

Currently Ken-way Excavating uses pipe bursting equipment from HammerHead Trenchless. For replacing 4-inch pipe, they have a PB30. It’s a small machine suited for tight spaces. Machines of other sizes handle larger sewer main work. And although typical demonstrations or online videos show equipment bursting clay pipe, it can do more. Technicians join HDPE SDR17 replacement pipes using a system from Connectra Fusion Technologies. 

“We can burst plastic, cast-iron, ductile iron and transite pipe,” Fisher says.

Not every job is perfect for bursting. Replacing pipe of one diameter with new pipe of the same diameter — in other words 4-inch with 4-inch — is typically less challenging. When the replacement is a larger diameter, the volume of soil displaced may become an issue. “In denser soils, there may be a problem bursting a 6-inch clay main to upsize it to a 10-inch,” Fisher says.

Sandy material is easier to displace than glacial tills, but hard-packed sand could also pose a challenge. Problems come from the usual arrangement on job sites where other utilities are often located near wastewater pipes. It’s those other pipes that may be affected by displaced soil. It doesn’t always happen, but it is a situation you have to think of and be prepared for, Fisher says. 

Other preparation is required for bursting. Every line is televised before and after the job. A pipe with an offset joint or a pipe that is collapsed can be replaced. A pipe with a long sag or belly is not a candidate for replacement because the lack of proper bedding will create a belly in the new pipe just as it did in the old one. After the work is done, Ken-way Excavating televises the line again to ensure the job has been done properly.

Many advantages

Where it can be used, bursting is much better than digging a trench, Fisher says.

“Why would you have an open trench 60 feet long when you can have two pits? You can prep two pits safely, and you’re not dragging a trench box along. For a pipe replacement, bursting takes about the same amount of time, but it is much less dangerous for the men. Buying bursting equipment increases your costs, but that is offset by the reduced risk and by fuel cost because you don’t burn as much as you do when digging,” he says.

Customers are happier, too, because their property damage is less. In one situation, there was a run of several hundred feet from a house to its septic tank. The yard contained several trees, and the owners didn’t want the roots damaged by digging. Pipe bursting did the job and left only a couple of pits for restoration instead of a long trench.

Pipe bursting is also good in tight situations where an excavator arm cannot swing, even a mini-excavator. In one case, a home had a large second-story deck. Instead of removing the deck, Ken-way Excavating technicians set up the pipe bursting gear in the basement and replaced the pipe from there to the septic tank.

Education is key

Murphy Pipeline Contractors, based in Jacksonville, Florida, is another successful business built around pipe bursting and other trenchless work.  

“It all comes down to education and working with clients to explain the processes and the benefits,” says Andy Mayer, company owner. “It’s taken about 15 years, but what I’ve seen in the U.S. — particularly with pipe bursting — is that trenchless technologies have become very accepted. It’s now gathering a lot of momentum.” 

Education has been an integral part of Murphy Pipeline Contractors’ growth since the company’s founding in 1999. It remains so today. Todd Grafenauer, company educational director, leads those efforts from the company’s Milwaukee office. 

For contractors who rely heavily on customer education to ultimately sell their services, Grafenauer says it’s important to understand the full scope of what customers need to learn. He also says contractors should be prepared to do a certain amount of work upfront with no guarantee that it will turn into a profitable job. 

“Our main goal is to educate communities on these technologies and the value involved. If we do a good job, it’s a pretty easy decision for them to move forward.”

Damage prevention

Along with educating your customers about why pipe bursting can be the preferred solution, it’s important to fully verse your crew in all aspects of the work as well — especially safety precautions.

During project planning, it is essential that all utilities are properly located and marked to show location, type of utility, size, pipe material and depth. This will allow your team to plan for temporary utility relocation or conflicts. 

As the new pipe is installed, a pipe bursting head serves three main functions as it is pulled through the ground. First, it fractures the existing pipe from the inside by applying a radial force created either by a static pull force or a pneumatically driven tool. Second, the existing conduit is expanded approximately 20 percent larger than the new pipe O.D. Lastly, and simultaneously, the new pipe is pulled in immediately trailing the bursting head. 

As the head travels through the ground, the earth must either compress or displace to receive the head and new pipe. Depending on the type of soil and the volumetric displacement of the head, forces will be transferred to an area immediately surrounding the pipe. 

A part of the work plan should include the anticipated “potential impact zone” of the pipe burst, and all utilities inside of that zone be located and exposed or relocated if they become damaged. In many cases, utilities that may conflict with the potential impact zone are “potholed” by use of vacuum excavation, which exposes them and either confirms they are outside of the potential impact zone or allows for the pipe bursting head to pass by safely, at which time the hole is then simply refilled.

In most cases, soil compaction and/or displacement is directed upward from the crown of the existing pipe and the potential impact zone is shown in detail and can be easily calculated.

In order to anticipate the potential impact zone, there are three major factors taken into consideration: the inside diameter of the existing pipe to be replaced, the outside diameter of the new pipe that is being installed, and the geotechnical conditions found inside the existing trench. By subtracting the inside diameter from the outside diameter and converting to a potential impact zone, a safe and successful pipe burst can be both planned and executed. 

It’s the responsibility of the entire team to promote work site safety and to use best practices when working belowground. Although pipe bursting does not open a trench for the entire length of a utility replacement, it does create forces belowground that require proper damage prevention practices be followed. 

Luke Laggis, David Steinkraus and Matt Timberlake contributed to this article. 


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