Trenchless trends in Northern Ireland

Sales of Hammerhead systems demonstrate a rise in pipe-bursting technology in Northern Ireland. Here we look at two recent cases

UMole, the mainland UK dealer for Earth Tool Corporation Hammerhead equipment, has announced two recent sales into Northern Ireland. Two Hammerhead Hydroburst HB5058 pipe-bursting systems have been sold to two separate pipeline contractors. This gives a clear indication of the growing call for pipe-bursting technology in the Northern Ireland market place. The first Hammerhead HB5058 was sold to Strabane-based contractor JJ McCrossan & Son, with the second being purchased by contractor Wilson Civil of Lisburn.
The Hammerhead HB5058 is static rod-based pipe-bursting system that utilises an optional 15.1kW Kubota-driven power pack to provide the hydraulic power for the pipe burster. The HB5058 unit itself is a 1,650mm long by 600mm wide by 341mm deep frame housing the hydraulically driven rod puller. Designed for the replacement of both water and gas mains made of friable materials, the rod puller generates up to 50 tonnes of pulling force, through an easy-clean jaw arrangement, using 50mm diameter, 1m long pulling rods. The HB5058 can burst pipes of between 76mm 255mm diameter over up to 100m lengths, which means that from a central bursting pit up to 200m of replacement pipe can be installed from a single set up.
The Hydroburst HB5058 has pin-joint tooling for quick and easy connection as well as robust construction on a unit that is easy to operate. As well as bursting more friable pipe materials such as cast iron, clay and concrete, when used in conjunction with specially designed splitter heads, the system can also be used for the replacement of existing ductile, steel and plastic pipes. The system is also compatible with Earth Tool Corporations' Air Impactor unit, which can assist pipe replacement works in the most difficult bursting situations.
JJ McCrossan was established 30 years ago by John McCrossan, with most of its work coming from open-cut water mains and sewer installations for the DRD Water Service in Northern Ireland. Brendan McCrossan, son of the owner, joined the company four years ago with visions of expanding and diversifying into trenchless technologies to capitalise on the growing popularity of the technique.
The new pipe-bursting rig has already seen action on its first job. The work, acting as a sub contractor, in a contract for Water Service, was located in Castlederg, County Tyrone, and involved the replacement of some 300m of 90mm diameter PVC pipe with 125mm diameter HDPE pipe.
According to McCrossan: "On day one, a pull of 100m was carried out using a ductile splitter bursting head in place of a conventional blade to help break the PVC and burst any repair clamps. In this 100m the head encountered 14 repair couplers which were pulled into the exit pit without any difficulty. On day two a burst of 200m was carried out without incident."
The increased production on the second day was possible because the contractor utilised the bursting rod back feed technique, available on the Hammerhead HB5058, which installs the bursting rods directly into the next section of pipe to be replaced while pulling the bursting head and new pipe through on the first section of pipe, removing the need to unscrew and re-screw the rods during the operation. This enabled the 200m of pipe to be replaced in just four hours of operation.
In mid-March 2006, the company started a contract for Charles Brand - Holleran JV as part of a water-main rehabilitation programme in the Ballymena area. This contract consists of the replacement of some 2,000m of 100mm diameter spun-iron pipe with 125mm diameter HPPE pipe. There will be1,400m of pipe bursting.
Wilson Civil purchased both a Hammerhead HB5058 Complete System, and an HB5058 Lower unit to update an existing rig. Wilson currently works with Farrans as a sub contractor on works which form part of Water Service's mains rehabilitation programme. One of the company's most recent projects was as sub contractor for pipe bursting work within a contract being undertaken by McNicholas Construction on another part of the mains rehabilitation programme.
The North Ards Rehabilitation project required the replacement of some 2,500m of 150mm diameter PVC pipe with 280mm diameter PE pipe. The work was to take place in the Black Abbey Road area.
Wilson decided to undertake this work with the Hammerhead HB5058 pipe bursting rig. While the manufacturer does not normally recommend this degree of upsize when using the Hammerhead HB5058, Wilson thought the machine would be able to handle the project sufficiently well. The local ground conditions varied somewhat across the operational site and at times included adverse rocky conditions.
Generally working on individual bursting runs of up to 100m, using ductile splitter bursting heads, Wilson was able to break out the existing 150mm diameter pipe and pull in the new 280mm diameter pipe without too much difficulty. Where conditions allowed and site circumstances were favourable, up to 200m of pipe bursting was able to be completed in one working day. This was made possible by the ability of the Hammerhead HB5058, while in the one launch pit, to feed its bursting rods directly through the body of the machine into a new length of pipe to be replaced while operating a bursting run on the adjacent pipe section as described above. This proved to be a major time-saving feature.
The use of a ductile splitter was found to be most effective on the existing PVC as it helped to prevent bunching of the PVC shards ahead of the bursting head, a phenomenon which has been known to occur when using standard bursting heads when replacing PVC.
Few problems occurred during the course of the bursting work, although on some specific bursting runs ground conditions did lead to some surface heave as the new pipe was pulled into place, although this was minimised.
Commenting on the project Stuart Robinson, project manager for Wilson Civil said: "Despite early concerns by the manufacturer that the upsize was going to push the HB5058 to its limits we felt confident that the work was achievable with this unit. As it turned out the work went very smoothly and the bursting rig performed very well. It showed it metal and proved to be quite powerful enough to handle the task asked of it and we operated well within the tonnage/pulling force limits available to us."

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