The coastal town Barwon Heads is well known as the location of the filming of the television series Seachange. The project

The clients for the HDD project are Matt Dean Constructions and Barwon Water.

The project involved the first of two bores being undertaken for a sewer transfer main, which was 185 metres long with a 790 mm PE pipe.

The technology behind the project, developed by AHD Trenchless, is the pitch up front technology and is achieved by drilling on grade to very accurate tolerances in all ground conditions, including rock.

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The ground conditions on this project were predominantly sand, with pockets of limestone. AHD Trenchless utilised a D80x120 Vermeer drill together with their own AHD Trenchless recycler, which has a capacity of 4,000 gallons. The pilot bore was initiated using a 180 mm drill bit and extreme care was taken during this important stage to achieve the 1 in 700 grade. This was a very slow process, taking three days.

The next stage, reamed to 350 mm diameter, went very smoothly. A bold move was then taken and the hole was reamed to 950 mm. The purpose of this was to ensure the reamer did not affect the straightness of the hole.

The final stage was to do a cleaning run, to clean the hole before installing the pipe. This was undertaken three times before the team could be satisfied the hole was clean. A total of 72 cubic metres of material was extracted from the hole and processed through the recycler.

Pulling the pipe in went very smoothly, with pullback pressure reaching 40,000 lbs. Once the pipe was installed the accuracy of the AHD Trenchless system was proven when the 750 mm hole was visible from one end to the other.

AHD Trenchless said “It was like the project had been microtunnelled. The system really works.”