UHP Waterjetting Removes Sewer Pipe Concrete
A recent project conducted by Lanes Group in the United Kingdom has reportedly saved three houses from demolition by using waterjetting to remove concrete from a sewer pipe.
A team from the drainage and wastewater specialists utilized ultra-high pressure (UHP) waterjetting, deploying the technique after the foundation concrete in the pipe proved too tough for conventional robotic cutting, Envirotec reports.
“This was one of the toughest concrete removal projects we’ve ever tackled, and involved contamination of a 150mm-diameter sewer,” said Lanes Operations Manager Calvin May.
“We believe the concrete may have been linked to a nearby building project. Foundation concrete is particularly hard and, in this case, had time to set solid, completely filling the pipe for 11 meters.”
According to the team, the only other alternative would have been to excavate and replace the pipes that were buried 3 meters under a row of homes north of London. However, that would mean that extensions from three of the homes would be demolished and occupants would be placed in temporary accommodations.
“We didn’t make very fast headway with a robotic cutter, which works by grinding down the concrete, so we needed a different approach. UHP jetting turned out to be a gamechanger,” said May.
“It was over 20 times as fast as using robotic cutting and prevented the need for an alternative solution that would’ve been much more costly and disruptive.”
The concrete was removed in 15 shifts, which is equivalent to three weeks of work. For the project, Lanes selected a Falch UHP pump combined with an IMS Robotics jetting system, which delivers a waterjet at 2,500 bar (over 36,000 pounds per square inch).
Six Lanes wastewater operatives then reportedly underwent Water Jetting Association hydrodemolition training and equipment supplier instruction to operate the system. In particular, this model has a jetting nozzle on the end of a hose encased in a flexible steel coil sheath.
Once guided into the pipe, a packer was inflated with compressed air to hold the nozzle firmly in place inside the pipe. A mini camera and LED lights allowed the operator to view the waterjetting, while controlling the nozzle with a joystick to direct it at the concrete.
The concrete was removed in one-meter sections, according to the report, with the exposed pipe strengthened by installing a cured-in-place pipe (CIPP) point liner made from fiberglass matting, impregnated with resin.
Once the resin had cured, the liner created a durable new concrete-free pipe within the pipe, with a design life of reportedly at least 50 years.
Lanes adds that it carried out the UHP jetting project on behalf of Thames Water and has now used the technique to complete other challenging concrete removal projects for the water company.