Concord West

Microtunneling over Railway Shutdown

Ausgrid let the head contract to Dunmain. Dunmain are an accredited Level One Service Provider working in the electrical industry.

Dunmain completed the construction of both shafts ready for the establishment of the microtunnelling equipment on site and for the jacking frames to be concreted in by Thursday prior to the weekend.

Due to the close proximity of the rail, only a few metres were drilled prior to the rail shutdown. The remaining works 30m of 700mm and 48m of 900mm pipe jacking were required to be completed during the shutdown which was scheduled to start at midnight Friday night and end midnight Sunday night.

Microtunnelling completion in tight timeframes

Break Through of Ø700mm Microtunnel: The night shift completed 8 pipes by noon on Saturday and the next crew another 4 to breakthrough at 5pm on Saturday afternoon. The head was removed, rods retracted and the annular space grouted between the pipes and the microtunnel on the Sunday shift. The conduits were inserted and then grout encased on the few days following the weekend.

Break Through of Ø900mm Microtunnel: The 20 pipes were jacked in over the weekend with work proceeding again on a 24×7 basis. Breakthrough occurred at 10.30am on the Sunday. The head was removed, rods retracted and the annular space grouted between the pipes and the microtunnel on the Sunday shift during the shutdown as required. The conduits were inserted and then grout encased on the few days following the weekend.