Melbourne Water has awarded to John Holland, a member of the Leighton Holdings Group, a 6-year contract to assist in the delivery of a number of major sewer tunnelling projects. The projects involved are potentially worth AUD160 million. John Holland will provide pre-construction and construction services. Visit www.jhg.com.au and www.melbournewater.com 23/04.John Holland, a 99% owned subsidiary of Leighton Holdings, who is itself 54% owned by Germany's Hochtief, has won a AUD301 million contract to build Melbourne Water's first stage of the northern sewerage project, which includes eight kilometres of sewerage tunnels in the northern suburbs of Melbourne to meet growing commercial and residential capacity demands. The sewers will range in size from 1.6 to 2.5 metres in diameter. Additionally, five major access shafts of up to 65 metres in depth and 13 metres in diameter will also be constructed, enabling two specially designed TBMs to be utilised. Project managers Connell Wagner and design joint venture SKM-Jacobs will be working alongside John Holland to deliver this project. Construction work is expected to commence shortly and this first stage of the two-stage project is due for completion by 2012. Visit www.nsp.net.au, www.leighton.com.au, www.johnholland.com.au, www.hochtief.com, www.conwag.com, www.skmconsulting.com and www.jacobs.com 33/07.Lovat signed a contract to supply a new RME115SE earth pressure balance TBM to John Holland for the construction of the Melbourne main sewer replacement. The 4-spoke chromium carbide plated mixed ground cutting head is equipped with back loading rippers (interchangeable with 394 mm disc cutters). The cutting head is powered by a 450 kW hydraulic drive system. Speeds range between 0-8.2 rpm with maximum torque of 1,040 kN. Located in the stationary shell is a two stage, two chamber integral airlock which is outfitted with an oxygen breathing system, pressure regulation system for maintaining a fixed set point of pressure to a maximum operating pressure of 4 bar. The 2.92 m-diameter mixed face TBM will bore a total of 2,088 metres with a maximum slope of 0.12%. The entire tunnel alignment is below the groundwater level where heights above the invert vary from 9 m to 11 m. Geology along the tunnel alignment consists of formations of Quaternary age collectively known as the Yarra delta group underlain by sequence of Tertiary formations. The basement geology of the site comprises folded Silurian sedimentary rock. These rocks generally occur well below the proposed tunnel alignment depth. The depth of cover above the tunnel crown level varies from 8 m to 12 m. The TBM is scheduled for delivery during the first part of 2009. Visit www.lovat.com and www.johnholland.com.au 28/08.