Pipe Bursting For Replacement Of Sanitary Sewer Laterals

7th In A Series From The IPBA
By Matt Timberlake, President, Ted Berry, Trenchless Technologies Team LLC, International Pipe Bursting Association Marketing Committee | November 2011, Vol. 66 No. 11

As pipes fail from root growth, joints become offset due to ground movement, corrosion and failure. The need for replacement or rehabilitation is the only option to remove the possibility of backup into private residences or disruption of service for commercial properties. On top of the impact failing sewer lines have on the users, the infiltration of groundwater into the sewer system contributes to overloaded public wastewater treatment facilities adding cost and the potential for overflows into community waterways. Sewer exfiltration will cause sewerage to leave the sanitary sewer line through breaks and failed joints resulting in a potential for contaminating the ground water under private property.

Two primary methods
The two primary methods of addressing private laterals with trenchless methods are CIPP and pipe bursting. These two options both have very distinct advantages and should be considered prior to traditional open-cut construction as the methods can provide long-term service life and meet national and local standards. CIPP is a method of rehabilitation which relines an existing pipe and can often be installed with no digging, whereas pipe bursting is a method of replacement which installs a new pipe with the same or larger inner diameter without the need to open-cut the entire section. However, some excavation will be required.

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A pipe that is structurally deficient, partially collapsed, has heavy root growth or severe offsets can be replaced by pipe bursting with little effort needed to prepare or clean the pipe unlike with CIPP lining. A pit or series of pits will need to be excavated to allow access for the newly installed pipe (typically HDPE or PVC) and the pipe bursting machine pit. These pits are strategically placed to limit disruption to the existing property including landscape, hardscape and city easements. The existing pipe is strung with a chain, cable or rod depending on the make and model of pipe bursting machine. It is attached to a pipe bursting head which is approximately 20 percent larger than the outside diameter of the new pipe to be installed and pulled through the existing pipe bursting it while simultaneously pulling in the new pipe. Almost all lateral pipe bursting is done through small tonnage static pipe bursting. However, small diameter pneumatic pipe bursting is possible.