Using Trenchless Technology to Fix Channeling Pipelines

By Denise Sullivan
Published: April 10, 2018 | Last updated: July 5, 2023
Key Takeaways

Channeling occurs most often in cast iron pipes. It is repairable through trenchless techniques but is frequently mistaken for a line belly.

During the 1970’s construction workers used cast iron plumbing to lay water and sewage lines to residential homes. While these lines are sturdy in construction, they were only designed to last about 25 to 30-years. As they aged, these pipes began to erode, causing unseen issues for homeowners. Now that their lifespans are coming to an end, owners are looking to trenchless technology to help repair the problems.

What Is Channeling

Channeling occurs when the sewer line bottom erodes away. Often, by the time a homeowner begins to experience a problem, the pipe bottom is completely gone. This issue is seen in horizontal lines, most commonly made of cast iron.

Channeling is frequently mistaken for a line belly or just "belly” in the pipe. However, there are subtle differences between the two. A belly in the line forms when the pipe itself begins to deviate from the original line slope. In this case, the line is still completely intact. The only way to correct this problem is the replacement of the entire pipeline section.

Some Problems Caused by Channeling

As channeling is the erosion of the pipe, it is understandable that this issue poses potential hazards for the homeowner. With the loss of the pipeline bottom, exposure to the soil underneath happens. Exposure to the surrounding ground leads to contamination entering the stream, which could be harmful to those who consume the water from the supply. Conversely, if the eroded line is a sewage line, the waste inside could contaminate the soil around it.

Another issue homeowners may see is the infestation of insects from the surrounding soil. While this is less of a problem than potential water contamination, it is still an undesirable effect of exposure. Additionally, the break in the line is a definite access point for tree roots to infiltrate the line causing further damage and blockages.

Along with pipe decay, soil erosion is another problem facing property owners. If the channeled pipe is in disrepair, the soil underneath is washed away. This deterioration could lead to additional structural problems for the line and property built above it.

Trenchless Techniques Used to Fix Channeling

Channeling is repairable using trenchless technology. Trenchless tech saves both time and money and without the hassles of destroying the lawn or home foundation. There are several different methods to repair this problem.


Sliplining is the technique of pulling a smaller line through the preexisting pipe. Workers seal this new line with grout on either end. The seal between the old and new pipeline is a heavy seal and may be difficult to deal with in the event of another line break.

Because this is a hard line, it is only used on straight lines with no bends. Sections of the pipeline with curves must be sliplined with different pieces of pipe and then connected, a process called segmental lining.

Cured in Place Pipe

Cured-in-Place Pipe, or CIPP, is very similar to sliplining. The method uses a pipe within a pipe configuration. However, with CIPP there is no grout needed to fill the gap between the host pipe and the new pipe liner.

CIPP uses a resin-permeated liner as the new pipe. It is soft and flexible during installation. The flexibility allows it to curve around bends and make one solid new line instead of connecting several straight pieces. Once the line is in place, it hardens to form the single pipeline.

With both sliplining and CIPP, the original line acts as a barrier between the new line and the surrounding soil. This wall offers protection from root infiltration and adds support to the new line allowing it to last up to 50-years.

Pipe bursting

There is a third trenchless option some owners may find useful. Pipe bursting allows for entirely new plumbing to run in place of the original. Unlike the other methods, this is not a line within a line.

Pipe bursting is just as it sounds. A bursting head attaches to a tool. When pulled through the line, the head breaks up the old pipe in a process called fragmentation. The new pipeline is connected behind the head and is subsequently drawn into place as the original line breaks. Pieces of the older line are pushed into the surrounding soil.

The method of pipe bursting is not often used to repair channeled pipes as only a small section may need repair. However, if the entire line has suffered from erosion, consider this option. Owners may also choose this method if they want to lay a larger diameter line in place of the existing structure.

Channeling is often misdiagnosed as a line belly as the two are very similar. However, a trained trenchless technician can tell the difference between the issues. Trenchless techniques such as sliplining and CIPP solve the problem within a few days in the case of channeling. However, trenchless repair is not possible for a line belly.

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Written by Denise Sullivan | Technical Writer @ Trenchlesspedia

Denise Sullivan

Denise Sullivan is an accomplished freelance writer from Louisiana, with a Associate's Degree in Journalism from Eastern Oklahoma State College. She also graduated from East Central University with a Bachelor's in Biology. Denise began her writing career writing operations and maintenance manuals and software utility manuals for flight simulators. Since, she has expanded her writing to a broad spectrum of topics.

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