Western Sydney Recycled Water Main Project

Project Overview

The Replacement Flows Project is part of the Western Sydney Recycled Water Initiative – a joint venture between McConnell Dowell, United Group Infrastructure and General Electric (Deerubbin Water Futures) with Sydney Water as the principal client. The completed project took tertiary treated effluent from the existing sewage treatment plants at Quakers Hill, St Marys and Penrith and treats it further in an Advanced Water Treatment Plant; the plant produces highly treated recycled water, discharged to the Hawkesbury-Nepean River to replace flows of drinking water from Warragamba Dam. The St Marys plant produces up to 18 billion litres of recycled water a year. To complete the infrastructure upgrade, a total of 55 kilometres of pipeline was installed and divided into five different operating lines.


Various Locations in Western Sydney NSW


OTR, shale and rock


McConnell Dowell


Various lengths up to 380m


355 and 560mm SDR 11 polyethylene




UEA was responsible for generating suitable bore designs, not only to successfully complete each crossing, but also to maintain required grades, alignments, tolerances and depth of cover. The design and construct aspect of the project enabled UEA to provide solutions that reduced restoration, minimised impact to sensitive Cumberland Plain Woodland and avoided trenching through areas of indigenous cultural significance.


Working closely with McConnell Dowell and Sydney Water, UEA successfully constructed the majority of trenchless crossings on the Replacement Flows Project using HDD. There were a number of bores on the project, with the most significant being:

  1. Old Windsor Road, Seven Hills – 144m of 355mm
  2. M7 Motorway crossing, Dean Park – 345m of parallel 355mm and 560mm
  3. Prospect Highway, Seven Hills – 384m of 355mm
  4. James Ruse Drive, North Parramatta – 133m of 355mm
  5. Bells Creek/Richmond Road crossing, Dean Park – 300m of parallel 355mm and 560mm
  6. Sunnyholt Road, Blacktown – 110m of 355mm

Due to exacting grades, difficult access, busy arterial roads and requirements of pinpoint accuracy, the use of Paratrak HDD guidance technology was required on four crossings. These locations were underneath the newly constructed M7 motorway, the busy intersection of Old Windsor Road and Powers Road, Prospect Highway from Seven Hills train station to Powers Road and a crossing of James Ruse Drive exiting parallel to the Caltex multi products pipeline.

For more information about this project or UEA Trenchless, please send enquiries to Steven Hopkins.

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