Articles & Case Studies

Fitting a round peg into a square hole

Posted: Monday 6th February 2017

Connecting a round pipe to a square box culvert in Whitehaven recently posed a challenge for contractors MetroRod Cumbria, as traditional methods couldn't be used. Instead, flexible Pipe Doctor no-dig patch repair and Sealguard II grout products, both supplied by Source One Environmental (S1E), were used to create a reliable joint.

"The run-off from this particular location was to a sensitive water course, so our repair had to be environmentally-friendly, causing no contamination, and therefore we couldn't simply concrete the pipe in" stated Steve Oakes, Metrorod Cumbria owner and MD.

Tony Hickman, Technical Sales Manager of S1E, volunteered to attend site with the Metrorod team to develop a solution together. "When we arrived, we found groundwater flooding from the culvert over the garden of a brand-new property on a development site," commented Tony. "The Metrorod team discovered various issues to be resolved, but found that the leakage was because the original pipe was not properly connected in to the culvert."

The culvert was a 400mm wide x 500mm high oblong shape. The original pipe was of vitrified clay but the upper section was to be replaced with 300mm diameter twin wall, which would need connecting directly to the culvert. A Pipe Doctor patch was wrapped around a 300-400mm packer and inserted into the pipe and the pipe was then placed in position. The packer was then pushed further through the pipe into the culvert and then inflated, while timber was used to pack the culvert into a 400mm square.

"The packer will inflate to 300mm to push the patch against the inside of the 300mm pipe. Where it leaves the pipe, and has more space, it will continue to inflate to 400mm to bond against each side of the now-square culvert," explained Tony.

"It is not uncommon for Pipe Doctor patches to be used as an adaptor between two different sized pipes or other conduits. This method leaves a smooth internal bore within the pipe, with a gentle taper between one size and the other. In this case, I drilled holes into the pipe so that the patch created a mechanical lock with the pipe in addition to its chemical bond to the internal surface," he continued.

Once the patch had cured, the packer was deflated and removed, leaving the pipe bonded into position. Some water was still leaking from the corners of the square culvert around the circular pipe and the SealGuard II product was used here to seal up these voids.

SealGuard II is a high-performance hydrophobic polyurethane grout, designed to swiftly stop high flow water ingress. It can be injected into flowing water of up to 3 litres per second and reacts in under 3 seconds.

"Despite there still being a fairly high level of water, we stopped the flow within seconds and repaired all leaks within a minute," said Tony.

Metrorod attended site the following day to complete the works. The adjoining downstream pipe was installed, using a patch to connect it to the pipe fitted the previous day. A hole was drilled within this pipe for easy insertion and removal of the packer and an inspection chamber added to this hole once the patching connection was complete.

"The repair we created has channelled the water flow properly, with no chance of any leaks. The products we used are durable so we know we won't need to make any further repairs any time soon. Tony's knowledge on-site was a great help to finding a solution that worked," commented Steve.

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July 2021

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