Melton RWP Primary Sedimentation Tank 3 Design and Construction

The intention of this project is to deliver a new PST for the plant to cater for growth in flows and loads in the Melton RWP catchment. PST3 shall contain a half bridge scraper arm with a peripheral drive, spiral rake blade sludge collection mechanism, energy dissipating inlet.

(stilling well), scum skimming weir, and scum beach. PST3 shall include new primary sludge.

(PS) pumps and primary scum pumps.

Great Western Water
Project Completion
August 2020 - April 2022

This project comprised of the design, supply, construction, testing, commissioning performance testing and of a new Primary Sedimentation Tank. Specific work packages included the following:

  • Bulk earthworks for and concrete construction of a 23m diameter sloped bottom tank;
  • Installation of a mechanical scraper mechanism with scum removal system;
  • Installation of sludge and scum pump stations;
  • Installation of inlet and outlet pipework in sizes ranging from 300mm to 700mm in DICL and MSCL; and
  • Installation of valve chambers and 600mm modulating valves including all tie ins and isolations.

To this project Waternish were able to bring innovations and value additions including:

  • Deviating from the tender design to propose a solution that eliminated the need for the sludge trailer to be reversed;
  • Provision of a lower maintenance cost PST solution that has a longer design life than the nominated solution. This also allowed for a reduction in the sludge ring depth, reducing the amount of rock excavation required; and
  • Installation of additional 600mm valves to increase the positive isolations available in the process to facilitate downstream maintenance.

The projects had challenges, the most significant being construction shutdowns and site capacity limitations implemented by the Victorian Government in response to COVID 19.

On each occasion we worked collaboratively with the GWW project manager to minimise both the program and the cost impact.