Stage 5 of the overall upgrade of the Coombabah and Elanora wastewater treatment plants was aimed at increasing treatment capacity and to provide anaerobic sludge stabilisation. Allconnex Water engaged Abergeldie to design, supply, install and commission process equipment to replace two existing gravity drainage decks at Coombabah with three new ones, and to demolish and replace one existing gravity drainage deck at Elanora. New polymer storage, batching, dosing and static mixers were also required at Coombabah.
The two plants are approximately half an hour away from each other, allowing the works to be managed under a single contract and project management plan.
Strict performance standards were specified, both for individual equipment elements and for the overall process outcome. For example, the sludge thickeners were required to produce a thickened sludge with a consistent dry solids content of 5 per cent. The polymer usage rate was also specified, based on a defined kg/tonne of dry solids.
As the project progressed, it became evident that upgrades were also needed to several other existing process elements related to the new systems, and that some redesign would be required to manage interfaces. Close liaison with the head contractor, other sub-contractors and the plant management personnel is necessary to coordinate interrelated works.Design, Supply three BFP, Polymer system, Civil and Electrical works at Coombabah & Elanora WWTP.