Overburden Stripping and Site Rehabilitation

Overburden Stripping and Site Rehabilitation

Overburden Stripping and Site Rehabilitation

Overburden Stripping and Site Rehabilitation

Location: Holcim Packenham Quarry, VIC
Client: LafargeHolcim
Start: December 2015
End: May 2016
Value: $1m

The Details

This project involved stripping 290,000m3 of overburden material in order to expose the rock shelf ready for quarry extraction. Stripped materials were then placed as a 1V:1.5H fill batter enabling the rehabilitation of a 200m long section, 30m high portion of quarry wall. Surplus excavated material was also used to fill low points in the quarry floor enabling better control of stormwater.

Dandenong Treatment Plant C.A.L.M.

Dandenong Treatment Plant C.A.L.M. (Capped and Lined Mound)

Location: Greens Road, Dandenong, VIC
Client: Melbourne Water
Value: $9.1m

The Details

Following on from Goldsmith’s successful completion of the Dandenong Treatment Plant Remediation project, Goldsmith was engaged by Melbourne Water to undertake the next phase of the project, which included the construction of a Capped and Lined Mound (C.A.L.M.) with the 600,000m3 of contaminated material stockpiled during the remediation project.

The CALM design incorporates a compacted clay and LLDPE Base Liner and a compacted clay and LLDPE membrane for the cap. It consists of 6 Cells, totaling 87,000m2 in area at the base and 89,000m2 of geomembrane in the cap.

Other features of this relatively complex design, include a gas collection system, leachate collection system and surface drainage infrastructure. The material tracking system developed by Goldsmith for the remediation project was further used to track each load of the 600,000m3 of contaminated material into its final position. This system allows waste from any area of the original treatment plant site to be located in its new position.

Goldsmith contributed significantly to the design of the CALM in the following areas:

  • optimising use of available materials in the drainage layer, resulting in cost savings and creation of 9,000m3 of repository air space
  • replacing capping filter sand with a geocomposite drain saving cost
  • eliminating 50% of subsurface pipes
  • saving 26,700m3 of landfill air space
  • consulting closely with client and designers to replace over-specified items for various components and sourcing equivalent lower cost replacement

DTP Site Rehabilitation

DTP Site Rehabilitation

Location: Greens Road, Dandenong, VIC
Client: Melbourne Water
Value: $12m

The Details

Goldsmith delivered this large-scale site rehabilitation project involving demolition of structures, removal of contaminated sludge and water management with Melbourne Water in an open contract relationship environment. The objective was to remediate the existing sewerage treatment plant so that the 190Ha site could be sold and redeveloped by Vic Urban.
The project consisted of Goldsmith undertaking the following activities:

  • development and approval of site environmental management plan
  • excavation and placement of over 600,000 m3 of contaminated sludge’s and waste (including asbestos) to stockpile
  • material tracking the excavated contaminated soils
  • validity testing of remediated areas
  • demolition of concrete and steel structures
  • removal of asbestos
  • design and installation of water management system to control water runoff into and from the site through use of irrigation and pumping systems

The biggest benefit to the client was the net result of all activities undertaken by Goldsmith, which enabled the works to be completed on budget and six months ahead of schedule. These activities included the following:

  • removal of contaminated soils and sludge as one unit material rather than separate items. This saved time and cost and also reduced the amount of testing required.
  • using existing start surface survey rather than resurveying entire 190Ha site providing cost saving
  • eliminating the majority of the dewatering pumps and systems by using water for dust suppression, providing a cost saving
  • purchasing second-hand site buildings rather than hiring, providing a cost saving
  • implementing boom gate and swipe card system providing greater environmental control, site security and payroll information
  • reusing all concrete from demolished structures by crushing and paving haul roads, providing a cost saving
  • prioritising remediation works to bring forward on the program the most important site areas, which provided time savings
  • developing a solution to drying wet sludge by using paddocks as drying areas
  • working with Melbourne Water’s Geotechnical Engineers to design and construct an alternative solution to dewatering the site
  • developing a solution for locating underground pipes when electronic method was considered unsuccessful
  • initiating aeration of odorous soil in existing lagoon floor rather than excavation and removal of material