Sewer pipes are subject to harsh pressures underground. While routine maintenance can help prolong lifespan, many pipes eventually begin to deteriorate and require more thorough rehabilitation.
Historically, sewer pipes that were cracked, leaking or deteriorating were completely dug up and replaced.
This required excavating along the entire length of the pipe to remove it, which often damaged or destroyed property in the surrounding area. It could also be dangerous, expensive and disruptive to the environment.
Trenchless sewer repair was developed as a less intrusive method of repairing damaged underground infrastructure. Instead of dig-and-replace, trenchless sewer rehab methods use the defective pipe as a host for a new pipe or liner. Rather than removing the damaged pipe, one of a number of methods is used to restore the existing pipe. These solutions have proven to be more efficient, cost-effective and environmentally-friendly, as well as safer and less disruptive to communities.
There are several common trenchless sewer repair methods.
First introduced in 1971, Cured-in-place-pipe (CIPP) is the most widely-used rehabilitation method today for sewer and storm lines. CIPP repairs the damaged pipe by inserting a flexible felt or fiberglass liner inside and inflating the liner to form a pipe within a pipe. The liner may be exposed to heat, ambient curable resin or ultraviolet light (UV) to cure and harden.
One of the earliest methods of trenchless rehab, sliplining has been used since the 1940’s and is performed by inserting a smaller pipe into the damaged pipe, grouting the space between the two and sealing the ends. Sliplining may use one of a few different materials, including high-density polyethylene (HDPE), fiberglass-reinforced pipe (FRP) or PVC.
Pipe bursting uses a bursting tool to crack the inside of the degraded pipe, and fragments of the old pipe are forced out into the surrounding soil while a new pipe is drawn in to replace it. There are two techniques used: pneumatic or static pipe bursting, the use of which varies depending on factors like pipe material and soil conditions.
Rather than rehabilitating the entire pipe, mechanical spot repair is used to restore specific points of the pipe, such as cracks, fractures, breaks, collapsed sections, points of infiltration, and offset joints. Technology like Quick-Lock point repair sleeves from PRT can be used to rehabilitate the damaged portion of the pipe and restore its structural integrity at a lower cost than most other methods.
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