The company utilised their Herrenknecht AVN 1200 & AVN 1800 tunnelling machines & systems on the project.
Three 1,800 mm tunnels were required under major railways, roads and Western Power infrastructure. The last crossing passed under the Kwinana Freeway and totalled 110 metres at 2150 mm diameter, which involved crossing under the existing south and north lanes and works underway for the South Metro rail extension.
The last of the crossings involved tunnelling Humes reinforced concrete jacking pipe 110 metres in one drive from a thrust shaft and retrieving a tunnelling machine at the receival shaft at the other side of freeway outside the freeway reserve.
Following completion of the drive grouting, the encasement pipe was undertaken through the ports and the annulus between the 1400 MSCL water carrier pipe and the 1800 mm internal diameter jacking pipe was grouted. The carrier pipe was installed in 12 metre lengths with a specially designed roller system and spacers to ensure no damage to the Sintakote pipe. Joints were welded as installed.
Article continues below…This is the latest in a number of high profile, high risk projects successfully completed to date by the company. Others include 1.3 km of tunnel under Perth International airport runways and taxiways; the Hunter River Crossing; several crossings under Mitchell Freeway, and Tonkin and Leach Highways; the Otway Gas Project microtunnelling retraction system (which was the Victorian Case Earth Award category 2 winner 2005), several crossings of the Gold Coast Pacific Motorway, and Hoxton Park Railway crossings in Liverpool, Sydney, to name a few.
In response to growing environmental concerns, including acid sulphate soils, contaminated ground and ground water and treatment (including disposal), lowering ground water table, and risks associated with works in unstable ground, the company has developed Vertical Cassion Shaft Sinking technology to overcome these. The methodology reduces the shaft footprint/excavation and ensures minimal dewatering is required. This in turn is economically cost effective and environmentally friendly.
Internationally the company has been working in the Middle East for several years on sewer pipeline construction projects.
