North Pine Water Treatment Plant

Zinfra was contracted by Seqwater to provide the detailed design, construction, commissioning and training related to the solids handling improvements at the North Pine Water Treatment Plant (WTP).

As part of the tender submission, several alternative solutions were offered and taken up which ultimately reduced costs for Seqwater, these included:

  • Change from a split level building with significantly long conveyors (25m+) to a two storey building. This reduced overall construction footprint, amount of access roads and new fencing requirements, and provided the ability to utilise common equipment including the gantry crane for unloading of polymer bulk bags.

  • Split delivery approach into two separable portions to allow separable portion one, being the new dewatering building to be delivered, commissioned and handed over to the client. In doing so, Seqwater can effectively dewater the lagoons using the Protheroe Road system and new dewatering equipment. This removed a significant contractor cost to Seqwater, with no requirement to remove the lagoon sludge to allow access for lagoon modification works completed as part of separable portion two.

The scope of works on this project included:
  • Backwash balance tank refurbishment and modifications to increase its feedforward flow to clarifiers with the inclusion of a TSS meter to monitor % SS concentration and provide polymer dosing control.

  • Refurbishment of existing clarifier concrete structures and upgrading from tube settler to lamella clarifiers, increasing their flow limitations and settling rate performance.

  • New centrifuge feed tank and pump station with an operating volume 230m3 to store 1% – 4% SS solution. Feeding forward with duty/standby pump station to the dewatering centrifuges at a maximum rate of 30m3/hr at 1.2% SS concentration.

  • New two–storey dewatering building to house the duty/standby centrifuges along with peripheral systems including, polymer batch and dosing equipment for both clarifier and centrifuge dosing, service water booster and air compressor systems to meet the demands of the new upgrade inclusive of a gantry crane to service the centrifuges and perform the polymer unloading process.

  • Modifications to the existing sludge lagoons including relocation and replacement of the existing Flygt transfer pump, new sludge lagoon transfer pump capable of transferring lagoon sludge to either the Centrifuge Feed Tank or the Backwash Balance Tank via use of manual valves, fixed pipework within lagoon 1B for use of temporary Sykes pump, and connection of the Centrifuge Feed Tank into the existing Protheroe Road pipeline, utilising the existing Flygt pump, to transfer sludge to the SDA drying beds.