Case study

Anglesea WRP Outfall Replacement

In 2015, Dunstans Construction Group was engaged by Barwon Water to design and construct an ocean outfall to service their Water Reclamation Plant in Anglesea, Victoria.

  • Its original outfall pipe had been crushed by the cliff collapsing due to erosion, creating a very short timeframe to complete the project before the Christmas holidays, when demand on the plant is at its peak.
  • Our state-of-the-art German-built Herrenknecht 250 tonne directional drill, the largest ‘crawler’ rig in Australia, completed the 700m installation of 355mm HDPE pipe. The innovative method of plugging the pilot hole and forward reaming to open up the hole, prevented drill fluid and cuttings escaping into the ocean near to the Point Addis Marine National Park.
  • The 700m pipe string was welded and strung out approximately 5km from the insertion point. On the day of insertion, the Point Roadknight Beach was temporarily closed as the pipe was towed out to sea, attached to the drill string by divers and pulled back
    into the hole.
  • Our team also designed and manufactured the 18m diffuser attached to the seabed at the end of the HDD pipe – allowing
    the maximum dilution rate for the Class 2 recycled water that the plant produces.

Dunstans successfully completed this design and construct project despite a restrictive work area, as well as meeting the strict environmental conditions set out for the project by stakeholders including the Surfcoast Shire, The Environmental Protection Agency, and the Department of Environment, Land, Water and Planning.

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Project quick facts

Client

Barwon Water

Description

Installation of a 355mm HDPE outfall and 18m steel diffuser to replace damaged outfall pipe

Project date

September 2015 – December 2015

Project location

Anglesea, Victoria

Pipe type

355mm SDR 9 HDPE

Crossing length

700m

Project cost

$2.5m

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