Bursting project replaces 100-year-old pipe in Sydney suburb
A team of workers used pipe-bursting to replace 100-year-old cast-iron pipe with new polyethylene pipe for water service in a busy Sydney, Australia, suburb. This case study from the April 2003 issue of Water & Wastewater International describes the project.
By Carola Schmidt
April 28, 2003 -- Australian pipe-bursting specialist Collex NoDig replaced nearly 800 m of old water mains to upgrade water services in Sydney's suburbs of Potts Point and Kings Cross suburbs using the Grundoburst 800G from TT Asia Pacific Pty Ltd, a subsidiary of Tracto-Technik GmbH of Lennestadt, Germany.
The contractor Collex replaced the original 200-mm diameter cast-iron pipe, dating back to 1897, with 225-mm diameter polyethylene pipe. The replaced pipe consisted of two sections of 580-m- and 190-m-lengths.
Project challenges include a highly developed area with many underground services, traffic congestion and the need to ensure water services cease 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, project manager for Collex NoDig, a subsidiary of Vivendi Environment of Paris, France. "For that reason, its critical that water services are restored each night so that people are not left without fire services."
Using the Grundoburst, the contractor burst 90-m runs, although the equipment can replace in excess of 200 m 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 burst sections and reconnected. The contractor opened nine access points, seven in Victoria Street, and two in Challis Street during the course of the project.
"Our operators found the Grundoburst 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. "The equipment is also very compact, which is particularly useful in the area we're working, what with all the traffic, pedestrians and underground services. 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.
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 new pipe. These compact machines require small pits, and minimise excavation costs and disturbance in 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 in diameter. Bursting speeds of 100 m per hour can be achieved, depending on pipe material and soil conditions. Power for the bursting unit comes from a TT B100 hydraulic drive unit, powered by a 43-kW diesel and delivering a maximum pressure of 250 bar.
Carola Schmidt is the marketing director for Tracto-Technik GmbH, based in Lennestadt, Germany.