Kellyville Gravity Sewer System

Posted 21 August 2016

UEA Trenchless has been awarded, and has commenced work on, a gravity sewer main installation in Kellyville using horizontal directional drilling (HDD) technologies.

Kellyville is located in the Hills District – 30 kilometres North West of Sydney’s CBD. The region is undergoing a growth period and due to the large number of new developments in the area, additional sewer mains are required to carry effluent away from these new developments.

The contract awarded involves the installation of 851 metres of 280mm PE pipe by HDD and 42 metres of 225mm PVC pipe trenched, both in sandstone. UEA has also been contracted to build seven manholes, including testing of, and connection to, the existing system.

UEA will install 480 metres of the pipe in one bore through solid sandstone using a Vermeer D100 and utilising walk-over tracking system. This bore has a constant horizontal bend and half of the bore is at 1% grade. The difficulty in this method is that the tracking sonde is housed behind the mud motor and therefore it requires experience to achieve this grade. The remaining 360 metres will be bored in three shots using a Ditchwitch AT4020. Two of these bores will be completed at 1% grade, leaving no tolerance for error.

Some difficulties that UEA’s team expects to encounter include tracking the HDD at minimal grade, sandstone ground conditions, ground water and tracking the HDD through bush and undulating service levels.

Once the pipe has been installed, the seven manholes will be constructed and then connected into the existing gravity sewer system.