Project Completion Date

July 2019



Comdain's Role

Principal Contractor

Value Range Category

$10m - $50m


New South Wales


Distribution Infrastructure

The Upper Canal is part of Sydney’s Upper Nepean Transfer Scheme constructed between 1880 and 1888 to supply the majority of Sydney’s raw water until the construction of Warragamba Dam in the 1960’s. It has remained in operation since originally constructed and still supplies up to 40% of Sydney’s raw drinking water to Prospect Reservoir. The Upper Canal has significant heritage value, it is listed on the NSW State Heritage register and within Local Environment Plans.

The structure of the Upper Canal is reaching the end of its engineering life. It is susceptible to stormwater and shallow groundwater contamination from intensive agricultural activities, unsewered residential dwellings and changes to the surrounding lands use. It has been taken out of service on several occasions for unplanned maintenance due to failures in the wall construction and leaks.

The Upper Canal was originally designed to convey up to 680ML/d. However, through natural deterioration of the Upper Canal’s structure and the need to perform extensive repairs in some areas, the current capacity is reduced to approximately 500ML/d.

This rehabilitation program is aimed to return the Upper Canal to its original capacity of transferring up to 680ML/day for up to 6 months at a time.

Work Undertaken

  • Relining 9km of the Upper Canal walls
  • Rebuilding 150 metres of the Upper Canal walls
  • Repairing 1500 metres of cracks on the Upper Canal walls
  • Drainage improvements by repairing or replacing 30 existing cross drainage flumes

Highlights and Innovations

  • Innovations used to improve the installation process and increase the production of the preparation and installation of the relined canal walls
  • A robust and effective design developed to ensure the project deliverables are achieved