Pipe Eludes Corrosion Issues
As long as there is clay and concrete pipe in the ground, it’s going to have to be replaced.
According to Ron Pool, superintendent of Jordan Contractors, he is replacing 9,000 ft of a clay sewer line in Norman, Okla. as part of the fourth phase of the city’s efforts to rehabilitate the failing infrastructure.
Sand has infiltrated a line located in a housing edition that is only about 17 years old. The rubber gaskets at the joints have deteriorated, allowing sand to fill the clay pipe restricting flow.
“By going in with polyethylene that is joint-free, we should never have a problem with sand entering the system again,” Pool said.
A polyethylene (PE) pipeline is impermeable as a result of being joined together with heat fusion and then allowed to cool. The resulting joint is as strong as the pipe itself.
PE and other methods
PE was first used in the gas distribution industry and is becoming more prevalent in the water and sewer industries.
Jordan Contractors has been using pipe bursting methods to rehabilitate failing sewer lines for the last three and a half years, and has been the low bidder on the last three jobs in Norman.
“Pipe bursting is a wide-open field,” said Jimmy Jordan, president of Jordan Contractors. “The business has been very active nationwide and in the last three years has been growing strongly in Oklahoma. The future looks to be even better.”
Pipe bursting was developed in Europe to replace deteriorating gas lines. In the U.S. it has become a preferred trenchless method of replacing sewer lines and is gaining popularity in the water market.
Other forms of trenchless replacement include pipe splitting, sliplining and in-reaming. Pipe splitting is performed generally in the same way as pipe bursting, except a metal cutting wheel is used to slice open the host pipe instead of bursting the existing pipe.
In-reaming uses a head that crushes up the host pipe and implements a vacuum to suck out the crushed material. Sliplining is used when the replacement pipe is smaller than the host pipe and there is no need to enlarge the host pipe.
No matter which method is used, PE is the ideal material for installation with trenchless technologies because it is flexible and tough enough to withstand the force placed on it during the pullback. In some cases, sliplining is implemented because even though the replacement pipe is smaller, it is made of PE, which has no buildup from corrosion, and the flow is as high as other pipes with larger diameters that have corroded over time, restricting flow.
The pipe bursting process entails digging an access at each end of a failed line and running a steel stem through the host pipe and hooking it to a bursting tool. The replacement PE pipe is connected to the back of the bursting tool. A horizontal hydraulic rig is used to pull the bursting tool back through the host pipe, breaking and expanding the existing pipe into the surrounding soil while simultaneously replacing the line with the new pipe.
Jordan Contractors has been overwhelmed with work and has three opportunities for pipe replacement jobs on hold while work is being completed on separate projects.
One reason for Jordan’s demand is the attention the company gives to the property owners. The company’s top priority is making sure it has little effect on the homeowner’s property.
For service hookups to the houses, Jordan uses small track excavators and enters and exits the property on a plywood path to prevent damage to the lawn.
A 3- x 6-ft hole is all that is needed to reach the main. They pile the excavated dirt on plywood and, after the connection is made, refill the hole and re-sod the area that has been disturbed.
“If this was an open trench operation there would be a lot of damage to people’s backyards—not to mention all of the extra work involved in taking down fences and moving storage sheds,” Pool said.