TT Asia-Pacific cracks pipes in New Zealand
Trenchless contractor G.P. Friel has completed the renewal of a 180 m pipeline using TRACTO-TECHNIK’s GRUNDOCRACK pipe bursting system in Wellington, New Zealand. According to the contractor the project could be the longest pipe cracking renewal ever undertaken in the country.
In Wellington, New Zealand, a section of 155 mm earthenware sewer on one of the city’s major southern arterial roads, Adelaide Road, was found to be in need of renewal. Local contractor G.P. Friel Ltd, who specialises in the application of trenchless techniques, was engaged by the infrastructure owner Wellington Water to complete the challenging task.
Engineering consultancy CH2M Beca had incorporated trenchless pipe cracking into the design of the project, which minimised the hazards associated with open trenching and reduced the amount of traffic disruption. The location of the project, in a built-up residential area, made CH2M Beca’s pipe cracking method the ideal solution to complete project works.
Upon inspection of the site and appraisal of the design, G.P. Friel realised that there was only one intermediate manhole with no significant change in grade and alignment. Therefore, a plan was put in place to break out in the intermediate manhole and pull the new high-density polyethylene pipe (HDPE) pipe, with an outside diameter (OD) of
160 mm, in one continuous length using the pipe cracking method.
The decision further reduced the number of excavations needed and the amount of time that would be required to work in traffic management. It turned the pipe cracking into a massive 180 m long renewal – the longest G.P. Friel had ever attempted with its TRACTO-TECHNIK GRUNDOCRACK PCG 130. According to G.P. Friel, it could also be the longest renewal ever recorded in New Zealand.
The GRUNDOCRACK is an air-driven pipe cracking machine, which works by shattering the old pipe while advancing through the old pipe. It radially displaces the fragments of the old pipe into the surrounding soil as it progresses. The bore hole for the new pipe is extended at the same time, while the pulling force of a winch supports the pipe cracker, guaranteeing safe guidance through the pipe’s route.
Following consultations with TRACTO-TECHNIK Asia Pacific Product Specialist Daniel Toms, G.P. Friel was confident that the GRUNDOCRACK PCG 130 pipe bursting tool and 5 tonne GRUNDOWINCH constant tension winch were more than capable of safely completing a burst of this size. The machines had previously been sourced from TRACTO-TECHNIK Asia Pacific’s base in Brisbane, Queensland and delivered to New Zealand.
In order to pull the 180 m length of HDPE pipe, a location had to be found where it could be welded into one string. G.P. Friel liaised with Wellington City Council Parks & Gardens and secured a section of the nearby McAlister Park for that purpose.
A launch pit was prepared the day before the burst. The pit was fitted with compliant skid resistant plates to protect it overnight. G.P. Friel also ensured that the receiving manhole and intermediate manhole were prepared and for excavation.
The work site needed to be over 360 m long to account for the receiving pit, launch pit and the 180 m of welded pipe all in one line. The long worksite also crossed through a busy intersection at the corner of Adelaide Rd and Luxford St in the suburb of Berhampore. This meant it was imperative that the contractor to liaise with local residents to ensure that one encroached on, or had access to, the worksite during the excavation.
G.P. Friel’s supply chain partner ATMS provided traffic management during the pipe cracking process.
The extensive preparation paid off and the burst was completed in a little under three hours, exactly what was planned by the design and construction team. The pipe was laid without incident with minimal disruption to the local residents.
G.P. Friel completed additional reinstatement on Adelaide Road following the pipe bursting, and a new manhole was constructed to improve access for future maintenance access, which has left the local community with a robust new sewer. The project, which strengthened the relationship between G.P. Friel and Wellington Water, is another example of the performance and reliability of the TRACTO-TECHNIK GRUNDOCRACK for the application of trenchless pipe cracking.
For more information visit the TT ASIA-PACIFIC website.
This article was featured in the March 2017 edition of Trenchless Australasia. To view the magazine on your PC, Mac, tablet, or mobile device, click here.
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