The work is for Sydney’s North West Rail Link. New South Wales transport minister Gladys Berejiklian said the start of geotechnical drilling along the 23-kilometre route was a significant milestone. The link will include Australia’s longest rail tunnels, at 15.5km.
“This is an important part of the design work currently under way for the project and will help produce a very detailed picture of what the tunnelling contractors will encounter as they build our nation's longest rail tunnels,” Ms Berejiklian said.
At least 150 boreholes with a diameter of up to 150mm will be drilled at various locations along the proposed alignment between Rouse Hill and Epping. The boreholes will be drilled to depths of up to 75m below ground and will be used to confirm underground geological profiles, rock types and other underground characteristics. This will be important in helping finalise the civil design for the stations including the 15.5km of tunnelling between Epping and Kellyville.
“The geotechnical work will assess all underground conditions to confirm rock and other subsurface conditions deep beneath the region’s streets and its suitability for tunnelling,” she added.
Last month, Coffey Geotechnics was appointed as the geotechnical consultant for the concept design stage of the North West Rail Link by the NSW Government. Coffey Geotechnics, with sub-consultant Aecom, will undertake geotechnical investigations, laboratory testing and analysis, and complete a geotechnical and contamination interpretative report including design advice for the Department of Transport.
“Quality geotechnical work will provide detailed knowledge to the project team about the ground conditions including the composition and location of soils, rock and water,” said Coffey Geotechnics NSW Manager Brett Hawkins. “It will provide more detailed recommendations for design optimisation to minimise risks.”
The geotechnical work for the concept design phase is expected to be completed in early 2012 to enable the tender process to begin for the construction and development phase of the project.