Understanding when and how to use pipe bursting (Part 6 in a series)
Underground service utilities in many cities around the world are getting old. Most current systems have operated beyond their reasonably expected service life, and a significant part of underground utilities are deteriorated and require costly maintenance and repair.
Problems frequently involve corrosion and deterioration of pipe materials, failure or leakage of pipe joints, and reduction of flow due to mineral deposits and debris build-up inside pipes. In gas pipelines, leakage can lead to the possibility of explosions. These problems are combined with the negative impacts of open cut repair/replacement projects on the daily life, traffic, and commerce of the area of a pipeline repair.
In recent decades, new trenchless technologies have emerged that are more cost-effective than traditional open cut systems. Among the new technologies, the pipe bursting technique has been the most popular.
Pipe bursting is a process in which the pipe replacement is carried out by pulling a new pipe behind a cone-ended bursting tool. The bursting tool is pneumatically or hydraulically driven and effectively hammers its way through the host pipe, displacing the fragments into the surrounding soil, while simultaneously pulling the new pipe into place behind it. Pipe bursting is a trenchless method that allows for upsizing the original pipe to increase the flow or storage capacity.
Pipe bursting originated in the United Kingdom during the early 1980s for total replacement of existing pipelines. It was initially created to replace small-diameter, cast iron gas distribution lines. Since then, the process has been used as an effective method for replacing pipelines diverse in size, material type, and function. Pipe bursting has been successfully utilized internationally and has gained recognition as a reliable substitute for open trench and lining methods for renewing pipelines. Conservative estimates indicate that there are more than 50 pipe bursting contractors currently operating in North America.
Pipe bursting can be used on almost any type of existing pipe—exceptions include ductile iron or heavily reinforced concrete. Currently, the applicable size range is from 5 inches to 50 inches. In addition, depth, soil conditions, peripheral utilities, and service connections will dictate whether pipe bursting is appropriate. Pipe bursting can be used to reduce damage to pavement and disruptions to traffic, hence limiting the social costs associated with pipeline replacement and providing a significantly smaller environmental footprint.
The design limits and factors to be considered by trenchless engineers include: ground conditions, groundwater conditions, degree of upsizing, construction and depth of the existing pipeline, adjacent utilities, and other site-specific characteristics.
So why pipe bursting instead of open cut replacement?
In most cases, pipe bursting has many benefits over open cut replacement of the same pipe. There are multiple advantages when comparing pipe bursting and open cut excavation. They include:
- Pipe bursting typically minimizes damage to the existing surface and surface improvements. This often means less restoration of streets and driveways, landscaping, and sod.
- Pipe bursting typically reduces the amount of time it takes to replace the line segment compared to open cut. Ultimately, this means there is less disruption to traffic patterns, business operations, and the community.
- Most often, the reduction in easement acquisitions and surface restoration, combined with the increased productivity of pipe bursting over open cut replacement, results in a significant cost advantage when using pipe bursting.
About the Author
Keivan Rafie’s engineering expertise is in tunneling, mining, and ground-improvement projects. For the last 15 years, he’s worked across the globe in Asia, Australia, the Middle East, and North America. Keivan’s knowledge and experience go deep with tunneling methods, such as drill and blast, NATM, and TBM, and he is involved in all stages from design to manufacturing and construction.More Content by Keivan Rafie