Haughton Pipeline Duplication Project
Using their extensive knowledge and experience in tunnelling and pipe installation, D.J. Mac Cormick Contractors successfully completed works for an integral water pipeline in north Queensland.
The Haughton Pipeline Duplication Project (HPDP) involved the duplication of a 36.5 km pipeline from the Haughton Pump Station to the Ross River Dam in order to provide a bulk raw water supply the area.
The alignment of the DN 1800 GRP pipeline included crossing beneath state-controlled Flinders Highway and a Queensland Rail (QR) rail corridor, which required D.J. Mac Cormick Contractors to install a 120 m long 2.5 m outside diameter enveloper pipe using the trenchless pipejacking method.
Before works began, several authority approvals and permits were acquired, including a QR Wayleave, compliance the QR’s civil engineering requirements and Department of Transport and Main Roads permits.
Detailed temporary design was undertaken for launch shaft shoring, thrust block, the concrete pad and entrance wall, as well as the receival shaft design for microtunnel boring machine removal, while the jacking system employed was capable of up to a 850 t safe jacking load.
A Herrenknecht tunnelling system was selected to undertake the project with a mixed cutting wheel chosen based on the expected ground conditions that ranged from stiff sand and clay to granodiorite rock.
The subsequent 120 m drive length was completed in 11 days at a depth of a maximum 2.5–3 below surface to top of pipe, followed by the grouting of annulus outside of the pipe.
Additionally, pre, during and post surface settlement monitoring was undertaken with maximum of 2 mm desettlement under the highway and railway. Spoil removal monitoring works were also undertaken on each pipe as the construction advanced to ensure no excessive excavation occurred and the 2.1m internal diameter concrete jacking pipes were supplied by Humes.
An air pressure test was conducted at the conclusion of the installation to certify the line to proper sewer standards and a detailed survey of the pipe post-construction found no defects.