Traditionally, Ipswich Water has used open trench methods for water main construction. However, for this project, the service corridors were already congested and positioning another pipeline on the footpath was not an option. The choices were to reconstruct on the existing alignment or go out on the road pavement. Ipswich Water opted for bursting the old main and installing in situ, a replacement 250 mm PN 16 Polyethylene water main and upgrading the associated water services.
The 160 metres of main, on the footpath of Robertson Road at Raceview, was split into two sections for water bypass control. Once the bypass was in place and connected, the main water valves were shut, with only a small leak on the uphill side, and work commenced. Ipswich Water used their larger Grundoburst 800G supplied two years ago by TT Asia Pacific, expecting this to be a tough job, beyond the scope of the 40 tonne Grundoburst that they also own. As it turned out, by using the right accessories for bursting cement-lined cast iron mains and attachments, the main was burst with only 16 to 20 tonnes of pullback force and the attachments such as Tees and Hydrants only required an extra 10 tonnes of pullback force to burst through these as well. The 225 mm main had only 800 mm to 1,000 mm of cover and there was concern over the potential surface damage to concrete driveways and bitumen side street crossings with the 290 mm expander but no such movement occurred.
The Grundoburst 800G was bursting through this all effortlessly and Terry Yates’ assistant Chris Pawson, asked Peter Decker of TT Asia Pacific about using the machine’s Rabbit mode (a fast mode automatic setting that works the machine at up to 40 tonnes). This mode is usually used for installing the rods prior to bursting and is controlled by the operator with a foot pedal switch which has the machine shuttle backward and forward automatically installing the patented ‘Quick Lock ‘ rods (no screwed joints on these rods to fail) at rates up to 120 metres per hour. In this case it was pulling in the expander and pipe at rates of 100 metres perhour and faster. The 75 metre section was installed in less than 45 minutes, much quicker than the experienced bursting crew and their supervisors were expecting.
Supervisor Terry Yates said “This example of bursting effectiveness has opened up a complete new area of activity for their bursting machines.” This was much to Terry’s amazement as he had expected some problems or dig ups at the very thick Tees and hydrant fittings. Peter Decker of TT Asia Pacific explained that the Grundoburst pipebursting systems from 30 tonne to 250 tonne have the least number of dig-ups on mains and attachments than any other hydraulic pipe bursting system, due to on going accessory and component development to produce the best available hydraulic pipe bursting system on the market for councils and contractors alike.Article continues below…
Pipe, expander and burst head connected onto rods ready to start.