The scheme is part of the New South Wales Government’s Priority Sewerage Program (PSP), which identified a need to provide a sewerage treatment scheme for the town of Appin, located south of Campbelltown. This entailed the construction of a new pressure sewerage reticulation and transfer system to service approximately 500 properties

Further to the contract works awarded in 2011, UEA was also asked to undertake an additional 2,006 m of directional drilling due to changes in design requirements, as well as several areas of environmental sensitivity.

To complete the work, UEA Trenchless mobilised a second Vermeer D100 x 120 directional drilling machine and support equipment to help complete the additional works within the desired timeframe and limit any possible delays that may be experienced with connection and commissioning works.

The scope of works under this subcontract included the detailed design, directional boring plans and construction of the transfer mains within a known mine subsidence area, inclusive of:

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  • Pipe welding and pipe stringing
  • Excavation of entry/exit pits
  • Drill and reaming of bore
  • Drill fluid capture and disposal
  • Pressure testing
  • Restoration of affected areas.

A total of nearly 5,200 m of directional drilling was completed by UEA Trenchless on the transfer main between the sewerage pumping station, through shale and rock.

Directional boring was selected, as the areas to be underbored include the sensitive Cumberland Plain Woodland, areas of heritage and Aboriginal significance and areas where grade requirements restrict traditional construction methods.

In 1997, the NSW Government announced the PSP to address the health and environmental problems caused by un-sewered urban areas within the Sydney Water Corporation area of responsibility.

The scheme has been rolled out over several townships with UEA having been previously involved in directional boring works in the Upper Blue Mountains, Freemans Reach, Hawkesbury Heights, Agnes Banks and Londonderry.

A spokesperson from the PSP said the project's anticipated completion will be in June 2012.