Trenchless technology from Mainmark rehabilitates leaking water main in just two days
Source: Mainmark - www.mainmark.com
Cross section of 460m of Primus Line installation in the water main.
30 September 2016
Ground engineering specialist Mainmark has successfully repaired a leaking water main in Lismore, New South Wales, completing the project in just two days with minimal disruption to nearby residents or power supply lines.
Using its trenchless pipe rehabilitation technology called Primus Line, Mainmark repaired the leaking pipe and increased its pressure rating to the required 16 bar, with no compromise to hydraulic pressure. It extended the service life of the main by at least 50 years.
Primus Line is a proven trenchless system for repairing long lengths of pressure pipes using a pipe lining inserted using the annular method. Installation is quick, enabling short rehabilitation times and delivering fast recommissioning of the affected pipe.
The large 225mmØ uPVC Class 9 water pipe travels up to 3.8 metres. The first section of the pipe runs downhill into a gully, with a length of 170m and a height difference of approximately 35m, where a scour valve is located. The second section which runs from the scour valve uphill, has a total length of 290m and a height difference of almost 50m.
Primus Line was installed in two sections. First, the water pipe was disconnected from the network and three excavation pits were erected. The scour valve was also removed.
Then, a pipe cut-out of 2m was created for access to the host pipe. This allowed a CCTV camera to be fed into the host pipe to inspect its condition, and facilitated a rope connection between the start pits and destination pit.
The CCTV inspection revealed two damaged sections of the uPVC host pipe, which were subsequently repaired with patch liners. It also uncovered multiple 15° bends in the route of the pipeline that were unaccounted for in the as-built drawings.
Despite this, the flexibility of Primus Line® allowed installation to continue as planned. The liner, which is manufactured in Germany and coiled pre-folded onto two timber transport reels, was inserted at approximately 4m per minute. Once it was tension free, compressed oil-free air of 0.5bar was pumped into the liner, expanding it to a round shape.
Four end fittings were then installed and mounted to a flange coupling adaptor at the uPVC host pipe. The final step involved disinfecting, pressure testing and reintegrating the pipe back into the water network.
Primus Line® features a three-layer composite liner made up of a polyethylene (PE) inner coating, a Kevlar® core to accommodate the operating pressure, and an abrasion resistant PE outer layer to protect the core during installation.
This semi-structural solution is not bonded to the host pipe and can traverse bends of up 45°. It can be inserted in lengths of 1,000m or more in one single pull. Primus Line® has a low wall thickness of only 6mm, which means the hydraulic capacity of the original pipe is almost maintained. The alternative relining solution is made of HDPE and would have reduced the pipe’s diameter to 147.2mm, compared to the 191mm achieved by Primus Line®.
“Primus Line® offers significant advantages over other relining products on the market: increased hydraulic pressure, rapid recommissioning and extreme flexibility to negotiate around bends,” said Russell Groth, Mainmark Business Development Manager.
For more information, visit www.mainmark.com (external link).
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