New Method Changes the Landscape in Pipe Bursting

Prechlorinated pipe bursting provides value, longer service life, and reduced environmental impact.

New Method Changes the Landscape in Pipe Bursting

New pipe is chlorinated, fused and pressure tested in the staging area before installation.

When Englishman Andy Mayer first visited the U.S. in 1999, he was shocked that such an advanced country was still using 20-ton excavators with 4-foot-wide buckets to install 6-inch pipe through the middle of subdivisions. He immediately saw the need for prechlorinated pipe bursting.

Shortly after Mayer’s introduction of the technology to North America, he spearheaded the efforts through education. Over the past two decades, prechlorinated pipe bursting has transformed the landscape of water main replacement technology by delivering value not seen with other construction methods.

A new way

Pipe bursting itself was developed in England about 40 years ago, the result of outdated pipelines and a few high-profile failures that led to a government mandate requiring the rehabilitation of aging gas infrastructure across the country. British Gas, owner of the largest gas distribution network at the time, was left with a dilemma of how to replace such a vast quantity of pipelines.

Replacing buried utilities was especially difficult in a city like London with its population of 13 million, swelling to 17 million during working hours, and its hundreds-of-years-old roads, sidewalks, and buildings. Limited easements and undersized distribution lines further complicated matters. British Gas needed an alternative to conventional open-trench work.

After much research and development, pipe bursting was born in the late 1970s, finally giving British Gas the tool to replace its existing pipelines in highly congested utility areas. With the success in pipe bursting natural gas lines, other utilities began to take notice of the technology and began to examine whether it would work for their systems, specifically waterlines and sewer lines.

Anglian Water in England took the technology one step further, developing a way of testing and chlorinating the new pipe above ground, then pulling it into place, super chlorinating, flushing and commissioning the new line — all in one day. This spawned the term prechlorinated pipe bursting.

In 2000, Mayer moved to the U.S. full time to establish Murphy Pipelines Contractors and introduce prechlorinated pipe bursting to North America. 

The process

Prechlorinated pipe bursting utilizes HDPE pipe and entails the preassembly and testing of approximately 300- to 600-foot lengths of pipe above grade at a nearby staging location. The staging area is located away from the burst locations to further minimize the impact of construction on the community. Once the pipe is proven to be sound by the pressure and disinfection testing, a series of small excavations are made and the new pipe is pulled into place by bursting the existing main. A post-chlorination and flushing of the main is then performed, and the new line is connected to the distribution system.

Ultimately, all services are connected in the new main and the surface area is backfilled to preconstruction grade. The entire process is completed within a single day, six to eight hours.

Less impact

Almost all communities have the need to replace old water pipelines, with limited resources. Today, we have multiple methods to pick from, ranging from traditional open cut to directional drilling, lining, and pipe bursting. When communities compare these methods and try to select the best option for a given project, they often find great value in prechlorinated pipe bursting.

As mentioned, the technology replaces 300 to 600 feet of pipe per day, which includes the main, services, hydrant, and valve, with pits backfilled. This speed of installation means large projects are completed in half the time of traditional methods. 

Community impact is always at the top of the list when engineers compare water main replacement methods. Pipe bursting reduces excavation up to 86 percent. These surgical excavations lessen the environmental impact, saving trees, roads, front yards and landscaping. Because the process uses less and smaller equipment, it also helps the community be more environmentally friendly by reducing greenhouse gas emissions from heavy equipment by 70 to 80 percent versus open-cut projects. There is also reduced noise and dust for residents to contend with.

Methods that are customer friendly in the construction world have always been challenging. With prechlorination, services are maintained and connected the same day. Compared to traditional open-cut replacement, prechlorinated bursting reduces customer complaints by more than 95 percent on average, thanks in large part to less excavation and the reduction of social impact as traffic can continue to flow freely.

Static pipe bursting also allows for the replacement of same or larger size pipe, all within the same utility path. Following the existing utility path allows communities to work off their existing GIS system for design, which requires less engineering than other construction methods and can fast-track projects to construction.

Overall value

High-density polyethylene pipe (HDPE/PE4710) has one of the longest design lives of any piping system available in the market, as tested by third-party labs and documented in multiple publications worldwide. The material is also fatigue- and seismic-resistant, moving with any ground movement, which eliminates a main cause of failure in more rigid or brittle piping systems. It also moves with freeze/thaw events and wet/dry cycles. 

The constructability of utilizing HDPE pipe with trenchless applications is significant. The material is lightweight and flexible with an allowable bending radius of 20 to 25 times the outside diameter of the pipe. It also has high impact strength.

While many communities may select prechlorinated pipe bursting based on its overall value, cost is still a major factor in decisions. Traditionally, based on the evidence of reducing upfront engineering costs, completing projects faster, and requiring 86 percent less restoration, prechlorinated pipe bursting typically reduces cost as much as 25 percent over traditional open cut.

As communities demand more value from dollars spent, prechlorinated pipe bursting continues to deliver an efficient process with a reduction in cost and community impact.

“Any other method would require the contractor to be in front of homes for days, sometimes weeks,” says Jessie Allen, a senior engineer with Arlington Water Utilities in Texas who has utilized the process on multiple projects. “And with efficiency, you can see how the process is aesthetically pleasing. As many of the residents along our projects are at work during the day, when they return, they hardly notice that anything has been done on their street. Customer satisfaction is key. If homeowners don’t know that their water main has been replaced and we don’t get customer complaints, we are receiving the value that the method offers.”


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