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'Problem Leak located to within a few millimetres'

Following a call from a UK water company, Ferret Technology agreed to assist with a particularly difficult water leak investigation and visited site on 17th January 2019. The site comprised a small cul-de-sac with four established properties. Property 1 was the focus of this investigation.

BACKGROUND

A ground microphone survey of the site had not produced any points of interest. A decision was then taken to excavate trial holes at the meter box and point of entry to the property. Respectively shown as A and B in the graphic. An attempt was then made to use a tracing rod from both points to determine the route of the leaking pipe but unfortunately obstructions were encountered in the pipe that prevented insertion of the tracer rod from either end. Initially thought to be pipe fittings it turned out that this was in fact due to sharp bends in the pipe line as shown in the graphic. Subsequent to this it was decided to use tracer gas to establish the leak position but this too was unsuccessful.

Discussions with the owner of property 3 revealed that in the past they had a water leak on their supply. Their insurance company undertook a tracer gas survey as part of their trace & access procedure. This too was unsuccessful so a decision was taken to relay the entire water service pipe from water meter to point of entry. Not unreasonably it was decided to excavate a third trial hole, shown as point C, approximately half way along the assumed route of the pipe to determine if the new supply to property 3 had been laid on the line of the existing supply pipes, the excavation proved that they were not.

CHALLENGES AND SOLUTIONS:

The challenges were; how to find the pipe route without further costly excavations, reinstatements and disruptions to property owners; how to find the exact location of the leak with confidence. If the leak couldn't be located the only option would be a full relay at significant cost.

The solution offered by Ferret Technology was to use its latest Ferret Leak Locator with enhanced sonde technology, enabling pin point location of the water leak position, mapping of the line of the plastic pipe and the dig depth required to access and repair the leaking pipe.

In view of the sensitivity of further trial holes on the site it was decided to introduce two additional tool kits developed by Ferret Technology to enable a No-Dig approach to finding the leak.

In consultation and with the agreement of the property owner it was decided to tackle the leak location using our reverse flow method from inside the property. A Size 1 Ferret Head with a rigid external diameter of 9mm was selected for use in the 1/2" black plastic water pipe. The Ferret Head was inserted into the leaking pipe inside the property by removing the Internal Stop Valve, which was located in an internal utility cupboard. Our Reverse Flow Kit was used to bring an overland water supply from our Boundary Box Adapter in the meter box, located approximately 35m away in the pavement, to the Ferret Leak Locator in the utility cupboard.

RESULTS AND OUTCOMES:

The Ferret leak Locator was used to locate the leak approximately 27m along the pipe from the insertion point. The umbilical cord connected to the Ferret Head contains a trace wire that was used in conjunction with a Cable Avoidance Tool (CAT) and Radio Signal Generator (GENNY) to map the route of the plastic water pipe. Following this the built in Sonde was used to pinpoint the exact location of the leak along the line of the pipe. In addition the signal from the sonde was used to calculate the dig depth required to access and repair the leak, in this instance the pipe was buried at a depth 120cm.

Much to the surprise of everyone the leak was on the opposite side of the shared driveway from the assumed route. The leak was under the block paving driveway of property 2. The actual line of the pipe and location of the leak is shown in the graphic

Setting up the Ferret Leak Locator, Boundary Box Adaptor, Reverse Flow Kit and determining the leak location and depth was achieved within an hour of arriving on site.

BENEFITS:

Clearly the water company, their contractor and the property owners were very pleased with the fact that this long running scenario had finally been resolved.

Richard Ingham, Managing Director for Ferret Technology Ltd who attended the site, said “This was the perfect Case Study for our Ferret Leak Locator; a No-Dig pipe entry to locate a leak that wasn't making enough noise for sophisticated sounding equipment to detect. In addition the unknown and deep pipe route under various different surface types meant tracer gas didn't get a result either. We were able to locate the leak and provide the dig depth all to within a few millimetres, demonstrating nicely the benefits our hydraulic leak location technology can deliver.

A useful schematic which covers the use of the No-Dig solutions described above can be viewed here.