Penrith Lakes – Tailings Dredging

Principal: Penrith Lakes Development Corporation

Location: Penrith, New South Wales

Contract Value: $7,850,000

Completion Date: August 2008

The Penrith Lakes Scheme covers an area of just under 2,000 hectares, located in the Penrith Valley bounded by the Nepean River and the foothills of the Blue Mountains.

The project involved dredging of approximately 1,300,000m3 of sand, silts and clays from a central tailings storage facility to a land reclamation site 4.4 km away.  The materials are being placed in a manner which enabled the coarser fractions of the tailings to be separated from the silts and clays.  This methodology allowed the coarser material to remain in the reclamation area where it was placed as a level one fill. The fine material was picked up with the tailwater from the reclamation site and pumped to a purpose built tailings facility adjacent to the reclamation.

A key objective of the project was the creation of enough volume in the central tailings storage facility to enable continued operation of the quarry processing plants. Also, the material dredged was used to increase the amount of land available at the Penrith Lakes site for future urban development as an end use for the site after completion of the quarry activities.

Scope of Work

  • Establishing a pipeline from the central tailings storage facility to Farleys Bay, a distance of 4,400 metres
  • Set up and maintenance of a Tailwater system to pump the fine material from the reclamation site
  • Establishment of a 1500 metre return water system to maintain adequate water levels for the dredge working in the central tailings facility
  • Dredge 1,300,000m3 of sand, silts and clays
  • Separation of tailings into two divided areas of Farleys Bay.  The eastern storage area for the coarser materials and the western storage area for silts and clays
  • Compacting of coarser tailings for future urban development

Challenges

  • Ensuring that the project was carried out with minimal disruption to the effectiveness of existing earthworks being carried out at the site
  • Ensuring that the project was carried out with minimal disruption to the effectiveness of existing earthworks being carried out at the site
  • Controlling the separation process of coarse and fine materials
  • Ensuring all work activities were undertaken in accordance with the mine sites OHS&E requirements