The first question asked when upsizing shallow water mains is usually “What about the ground heave?” This has been proven to be of no concern when the suitable machine and accessories are chosen.
The project at Pentecost Avenue, St Ives, was to burst 160 metres of existing 375 mm cement-lined cast iron water mains and all attachments and repairs, and install a new 400 mm Polyethylene (PE) water main.
There were many restrictions onsite to contend with, ranging from the start and finish times which were permitted between 9 am and 3 pm to suit local traffic conditions, to the fact that the 400 mm PE pipe had to be welded together a long distance away and brought to site when ready to install. Also, machinery had to be very careful around the trees along the route to avoid any damage above and below ground. The crew had this all worked out from their years of experience working with the other three smaller Grundoburst machines that they already own.
Depth of the main ranged from 0.6 metre cover to 1.5 metre cover over a total length of 160 metres. The Grundoburst 1250 G with ‘Quick Lock’ rods was chosen to ensure that there was plenty of reserve power and using the correct accessories ensured that there were no problems with this installation. Ground heave was one of the other major concerns expressed by the senior people from Veolia Water Network Services, particularly in the shallower sections and with the main positioned under the concrete kerb. During the course of the burst, some sections of ductile repairs were encountered with the blades breaking through two out of three sections. On the third repair section the upstream pipe collapsed allowing the repair fittings to move. Once past this, the burst was completed.
The burst was split into two 80 metre runs with one completed on each of two consecutive days. On both days, the Quicklock burst rods were installed in 45 minutes and the PE pipe and accessories were quickly connected onto the burst rods. The pipe installed on the first day only required about 50 tonnes bursting power – no repairs were encountered on this first run. This was also the shallow section with the greatest concern about ground heave. After the expander head had come through, the ground had moved slightly on the grassed footpath behind the concrete kerb but it settled back down in the following hour or two, to everybody’s expectation and satisfaction.
On the second day, the time to pull in the PE pipe was longer due to the ductile iron joining fittings moving along with the collapsing pipe, but once past these sections bursting proceeded without stopping and within the time constraints. At two stages of this burst the machine was pushed to 110 tonnes, which was a good test of the machine and the machine pit preparation. It was comforting for everyone to know that this reserve power was there when required. The other concern about surface movement was a non-event in this slightly deeper section.
With this new machine now operational, Veolia Water Network Services has the largest range as well as the largest working Static or Hydraulic Pipe Bursting machine here in Australia and during the next two months will be installing about 3,000 metres of 450 mm PE Trunk mains with the 1250G.
The Grundoburst 1250G with the unique and patented ‘Quick Lock’ rods is capable of installing pipe up to 630 mm in size, bursting through all pipe materials including cast iron, ductile iron, steel, VC, AC, concrete and steel reinforced concrete pipes as well as PE, PVC and even old lined-pipe systems. These machines are not limited to water main replacement only as they are regularly used for sewer, stormwater and other industrial product line replacement as well as swagelining and slip-lining.
The other machines in the unique Tracto-Technik Grundoburst system range from 20 tonne to 250 tonne pulling force, all with the ‘Quick Lock’ rods for simple assembly and disassembly of the burst rod string with all machines working at 100 metres per hour or faster. Further information on the projects or machines can be obtained by contacting TT Asia Pacific on (07) 3420 5455.
