Maiden HDD complete for Unitywater's sewerage main upgrade
Completed pipeline installation, entry side at the Kawana Sewage Treatment Plant.
April 3, 2017
The Wyuna Canal section of Unitywater's Mountain Creek to Kawana Sewerage Pipeline Project is complete, with Pipeline Drillers successfully drilling 908 metres to install a new 900 millimetre HDPE sewerage pipeline from the Kawana Sewage Treatment Plant to the western side of Kawana Way, north of the Parrearra Channel bridge.
This is the first of three horizontal directional drills incorporated in the project design, with drill rig heavyweights, Herrenknecht 250t and Gallagher HDD660 assigned to ream the borehole to a final diameter of 1200 millimetres.
The Gallagher commenced the pilot hole on February 22, entering at the treatment plant and drilling with precision to surface one week later within 500 millimetres of the exit peg. An excellent result as this section involved the challenge of crossing underneath the Wyuna Canal, which runs parallel to the Mooloolah River and adjoins the stunning Mooloolah River National Park.
Following this initial milestone, the Herrenknecht 250t drill rig setup exit side to assist in completing three reaming passes using a set of combination reamers (barrel and fly cutter), 26, 36, and 52 inch, before conditioning the hole with a 48 inch cleaning barrel.
During this time, the stringing and welding together of 12 metre lengths of 900-millimetre high-density polyethylene pipe weighing 2.5 to 3 tonnes took place at the northern end of Kawana Way, opposite Island Point Villas. Once completed to the final length of 920 metres (allowing for the connections on either end), this large diameter black and cream striped pipeline extended nearly a kilometre alongside Kawana Way, becoming an unmissable sight for Kawana Island locals.
With the pipeline and borehole ready and waiting in the wings, the Unitywater, Bamser and Pipeline Drillers project team and crew prepared for the main event of pipe pull-back (installation) just over four weeks after drilling commenced.
Within approximately eight hours, the Gallagher, pulling from 30 up to 220 tonnes of its 330 tonne capacity and with the assistance of three 80 tonne excavators to hoist and guide the pipe along with a dozen crew members, took the honour of successfully installing the new pipeline (pictured above).
Before commencing works, Unitywater and Pipeline Drillers reviewed the initial design of the Mountain Creek to Kawana sewerage pipeline and increased the trenchless methods utilised to a total of 70 percent. Thus significantly reducing the amount of vegetation cleared, ensuring the natural ecosystem of the Mooloolah River, one of the coast's most significant protected lowland habitats, is preserved.
Overall, stakeholder sentiment towards this essential upgrade project which will benefit residents and business owners from South Buderim to Mountain Creek has been extremely positive, with nearby residents, community and environmental groups engaged with throughout each stage of construction.
The next section of this Unitywater project involves crossing Kawana Way from west to east by microtunnelling, and is expected to be completed shortly after Easter. Local residents, business owners and community groups nearest works will be contacted closer to commencement. For all the latest project information, visit the project page here.