Renewal of Secondary Sedimentation Tank 17 & 18 - Aqua Metro Pty Ltd
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Renewal of Secondary Sedimentation Tank 17 & 18

Renewal of Secondary Sedimentation Tank 17 & 18

Small Scale Capital Program


Melbourne Water


Eastern Treatment Plant

Key Sector

Water and Sewer

Contract Type



15 Months
July 2018 to October 2019

Key Facts

  • There are 26 Secondary Sedimentation Tanks (SST) at the Eastern Treatment Plant (ETP) have been in continuous operation since commissioning in 1975.
  • Secondary Sedimentation tanks are used in the secondary treatment stages of sewerage treatment process.


  • A condition assessment was carried out by Melbourne Water in which degradation of concrete, sealants, and steel coating was identified.
  • Rehabilitation of the tanks needed to take place in a safe manner with limited disruption to the operations and adjoining facilities. Purpose of the Rehabilitation work was to enhance the asset life.

Scope of Service

The scope of work comprised of the following:

  • Emptying and cleaning of SST17 and 18
  • Undertake appropriate scanning to identify any hidden services
  • Condition assessment (visual) of existing concrete and steel structures to verify extent of works to be performed
  • Design and fabricate any temporary structures/platforms required for works
  • Renewal of existing floor and wall sealing.
  • Coating of internal walls of SST with epoxy coating
  • Rehabilitation of coating on reinforcement steel
  • Rehabilitation of coating on structural steel.
  • Provide reports on the remediation works


  • Asbestos were identified in the existing sealant material which were removed fully supervised and monitored by a qualified hygienist.


  • Works were carried out with controls in place to ensure no hazardous liquid could enter stormwater system on site.

Stakeholder Engagement

  • All works were carried out in coordination with Operations team at Eastern Treatment Plant and Major Capital Delivery team.