PIPE BURSTING
GRUNDOBURST plays key role in water services upgrade in Sydney, Australia by Tom Hughes, Managing Director TT Asia Pacific
Australia’s first Grundoburst 800G pipe burster has been an important contributor to the success of a major pipe bursting and replacement project in one of Sydney’s best-known and most built-up suburbs. Pipe bursting specialist Collex NoDig is using the Grundoburst 800G in the replacement of nearly 800 m of old water mains in the Potts Point/Kings Cross region. The original 200 mm diameter cast-iron pipe, dating back to 1897, is being replaced with 225 mm diameter polyethylene pipe. The pipe to be replaced consists of two sections: one 580 m long and the other 190 m long. Challenges facing Collex NoDig in this project include the built up nature of the area, with many existing underground services, high levels of vehicular and pedestrian traffic, and the need to ensure water services are cut off for only a few hours. "In this
area, there are many high-rise apartments, all with automatic fire systems to protect the properties and their occupants,” said Todd Stenning, Collex NoDig’s project manager. "For that reason, it’s critical that we have water services restored each night so that people are not without these fire services.” Using the Grundoburst, Collex NoDig has been bursting 90 m runs, although the Grundoburst is capable of replacing in excess of 200m of pipe per day in favourable conditions, due to the quick relocation abilities of the machine. The Grundoburst 800G bursts the existing pipe; then the polyethylene pipe, welded in sections up to 90 m long, is fed into the burst sections and reconnected. During the course of the project, which started in early July, Collex NoDig is opening a total of nine access points, seven in Victoria Street, and two in Challis Street.
“Pipe bursting remains a key tool in pipeline rehabilitation, as it is the only technology suitable for both pressure and non-pressure rehabilitation, ...” 22
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A job of this length would normally be completed in just a few weeks. However, due to the congested nature of the site, the high level of service connections and cross connections, the project is scheduled for completion in August. "We’ve been very impressed with the Grundoburst,” said Stenning. "It’s a very advanced machine in terms of its technology, and achieving what we want from this job. "It’s also very compact, which is particularly useful in the area we’re working around, what with all the traffic, pedestrians and underground services.Normally, you’d expect a much bigger machine with this amount of power. "Our operators found it very easy to operate. We had about a day’s training from the supplier, TT Asia Pacific - plus we’ve had plenty of experience with pipe-bursting equipment - and that was all we needed,” he said. ‘In addition, forward motion and all hydraulics are electronically controlled, and there’s a digital readout which very clearly shows what’s going on. That’s a key feature.” Stenning said the Grundoburst’s QuickLock rods were a lot quicker and easier to use than conventional screw-type rods, both when inserting the rods into the pipe, and hauling back with the pipe-bursting head and replacement pipe sections. "It’s a very quick action; you just drop them into place, lower them down, push the rod forward and you’re
ready for the next one. Pulling back, the operation is simply reversed. They don’t tend to jam like the screw-type rods can - often we’d need to use a Stillson to tighten or unscrew them - and the maintenance is a lot less,” he said. Collex NoDig (formerly known as No-Dig Pipelaying Pty Ltd) was formed in 1991. The involvement of Collex, a subsidiary of Vivendi, the world’s largest water company, brings significant resources to the organisation. Following this involvement, the business has recently expanded its range of services from being Australia’s leading pipe bursting company to now also providing a range of other rehabilitation services such as insitu lining, robotics, grouting, patch-lining and house service lining. As a result of this, Collex NoDig is now a total service provider in rehabilitation of underground pipes. Pipe bursting remains a key tool in pipeline rehabilitation, as it is the only technology suitable for both pressure and nonpressure rehabilitation, upsizing, and size-for-size replacement without any loss of internal capacity. Key to Collex NoDig’s success has been its relationship with industry-leading suppliers such as the TT Group (represented in Australia by TT Asia Pacific), who continue to supply the equipment to keep Collex NoDig one step ahead of its competitors. TT Group’s Grundoburst range of pipe-bursters includes 400 kN and 800 kN machines. Both comprise a rig with hydraulic cylinders, a hydraulic power pack, patented QuickLock bursting rods with bursting head and various diameter expanders for pulling in the new pipe. The compact nature of these machines means that small pits are required, minimising excavation costs and disturbance of the work area. The Grundoburst 800G can deliver 380 kN of thrust and 770 kN of pullback, and is suitable for pipes from 80 mm to 450 mm nominal diameter. Required pit dimensions are 3400 mm long by 800 mm wide by 250 mm deeper than the pipe being replaced. Bursting speeds (dependent on the pipe material and soil conditions) of 100 m per hour can be achieved. Power for the bursting unit comes from a TT B100 hydraulic drive unit, powered by a 43 kW diesel engine and delivering a maximum pressure of 250 bar.
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