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What is trenchless pipe repair and how does it compare to the open-cut method?

Have you ever turned on your tap and thought to yourself - where does my water come from? How does it get to my house?


While that thought may not often cross your mind, rest assured there are thousands of people worldwide that think about those questions every day. These people make sure that your water is clean, can be transferred to your house/business, and, when something breaks, they're responsible for fixing it.


It is the last point - rehabilitating a pipeline - that we would like to focus on here. And there are a couple of things that are helpful to know regarding pipelines and what it takes to repair them.

  1. Most all pipelines that touch our daily life are buried. This is generally necessary given city planning and space, but it then makes it difficult when those pipelines break or have problems.

  2. The majority of pipelines that touch our daily lives are owned and operated by cities, which work on tight budgets and schedules.

  3. Most pipelines are fairly old

  4. The disruption to social life caused by replacing full pipelines can be immense

So, given the nature of pipelines (being buried mostly), their age (mainly old), the organizations that own and operate them (governments and cities) and the impact that replacing a full pipeline can have on a city/town (huge), it is no wonder that people began trying to find a way to repair these pipelines without having to replace them.


A short history on trenchless pipe rehabilitation


The man first credited with inventing trenchless rehabilitation is Eric Wood, who invented the Cure In Place Pipe (or CIPP) in 1970. Once this was established as a viable method - and more importantly companies and cities were willing to pay for it - it was off to the races.

Eric Wood the inventor of trenchless pipeline rehabilitation.

Nowadays, there are numerous methods of trenchless rehabilitation - so many in fact that we won't list them here. As an example of that, Amex Sanivar actually started as two companies - Sanivar, focusing on CIPP liners, was founded in the mid 1970s. Amex, focusing on internal pipe repair seals, was founded in the early 1980s. Many of the most used trenchless methods today come from this era of great exploration.


For a more in-depth read on the history of pipes, you can read our article here.


When Pipes Break

When a pipe has a hole in it, joints get separated, or worse yet, a section of pipe collapses, this can have catastrophic impacts on the surrounding area and the people that live there.


While the 99.9% of pipe breakages or damage aren't this severe, we are still talking about the loss of our natural resources. In order to help preserve these resources, these pipes need to be repaired.


Open Cut vs Trenchless

When discussing damaged pipelines, the question of how to fix it can generally be broken into two categories: open-cut vs trenchless.


Open-Cut pipe repair ©RomanPentin via Unsplash

Open-cut describes the fact that the pipe must be dug out of the earth. The ground is "cut open" to provide access to the pipe. For cities, that means shutting down streets either partly or fully. For parks and other nature areas, this means digging up the area. Depending on the size of the pipeline, the construction site could be there for months.


This is how pipelines were primarily repaired before the 1970, and to this day it is still a popular option.


But with the advent of trenchless technology, many of the cons of the open-cut method could be solved. For a 100m long pipeline, instead of digging a trench 100+ meters long and 4-5 meters (dependent on pipeline) wide, a trench could be cut at both ends about 2x3 m in size (depending on the type of trenchless repair method chosen). This then minimizes the impact on the environment and also increases the speed at which a job could be completed.


When you realize that the majority of a project via the open-cut method is just getting to the pipeline and then reburying it when the work is finished, it is no wonder that a trenchless solution was created.



Costs

After discussing the method by which the pipe will be repaired, it is important to then discuss the (normally) primary factor in choosing a method - costs.


It is important to remember that generally it is a city or municipality that is in charge of repairing - or more precisely hiring out the repair of - the pipeline. Cities and municipalities generally work on tighter budgets, and they tend to stick with what they know - which is the open-cut method. Plus, it can sometimes take years to introduce new products to a city or municipality once all of the testing and everything is done.

And, when it comes to costs of an open-cut vs trenchless solution, most people tend to focus on the direct comparable of material cost. So what does one meter of "new" pipe cost versus what does one meter of a trenchless repair product cost. Generally, the cost of the PVC pipe section (most common product used in the open-cut method) is cheaper than the trenchless repair product equivalent. But, it is when you dive into the details of everything surrounding each of the installation techniques and methods that you really begin to understand the actual costs.


And one of the major costs is simply how long do you need to block a street off, how long do you rent equipment for, how long do people need to work there, and how many sub-contractors need to be involved? And the longer the pipe section, the greater these numbers grow for the open-cut method. By the very nature of the trenchless method not needing to dig out the whole pipe, these costs don't increase at the same rate they do for the open-cut method.


As we mentioned above, a trenchless job can be done in a week - an open-cut job can be done in a month, depending on the length of the pipe. These costs can add up quickly.


Disruption to social life


While calculating the costs of digging a trench to repair a pipe, most of the time the focus is placed on the actual monetary costs of the project - how much will the city or municipality have to spend to repair the damaged pipe. This makes sense with budgets and timelines to consider.


But, what is often not factored into the costs are the impact and disruption to the local area. How will the construction affect local traffic? Will bus lines or other transportation lines have to either be re-planned or stopped all together? What about the noise for the locals that live closest to the job-site? And how long will everyone have to put up with disruption?


Providing a monetary value to these numbers is difficult, but the cost to social life should not be forgotten when determining the cost of the project.



Flexibility of the chosen solution

In some cases, there may only be one solution that is truly viable for repairing the pipeline. Sometimes the pipeline runs under streets, buildings, parks or nature reserves that simply cannot be dug up. This is when the trenchless method really shows its value.


As an example, Amex Sanivar rehabilitated a pipeline running through the Kirstenbosch National Botanical Garden in Cape Town. Due to the nature of the botanical garden, there was no way that any sort of digging would be permitted. In fact, the reel that the eventual product SaniTube© was delivered on was barely allowed. Thanks to partners Bodotex is South Africa, the liner was able to be installed by hand, demonstrating the flexibility of the solution.



Final Thoughts

Considering how many kilometers of pipeline surround the earth, there are surprisingly few methods for repairing them when they break. These methods can really be broken down into two categories - the open-cut method and the trenchless method.


Both have their advantaged and disadvantages. There are some cases where only the one or the other can be used. But in the majority of cases, there is a choice to be made - which method do you choose?



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