Let’s talk about the Winton wastewater treatment plant

Option 1 – Discharge to water optimisation

Treatment performance of existing wastewater treatment plant (WWTP) is enhanced through additional aeration, desludging regime, addition of chemicals or baffle curtain to oxidation pond, retain existing stream disposal.

 

Option 2 - Discharge to water add-on treatment

Additional treatment processes for ammonia and DRP removal (activated sludge treatment, extended aerations), retain existing stream disposal.

 

Option 3 – Discharge to water tertiary treatment

Additional disinfection process after wetland (UV, membrane filtration), retain existing stream disposal

 

Option 4 – Discharge to water – new WWTP current location

Winton pond is replaced with a new treatment plant, likely a high rate process.

 

Option 5 – Discharge to land 90% - existing WWTP

Minimal change to treatment process at Winton WWTP, liquid effluent from wetland pumped to irrigation system

 

Option 5a – Discharge to land 100% existing WWTP

As for option 5 but with 100% land disposal

 

Option 6 – Discharge to land 90% - add on treatment

Additional treatment process for AmmN, DRP removal and UV, then to irrigation system

 

Option 6a – Discharge to land 100% - add on treatment

Existing wastewater treatment plant enhanced. New pump station. Treated wastewater pumped to and discharged to land (either via surface or sub-surface irrigation). Note: Image is guide only. Land location undetermined at this stage.

 

Option 7 – Plant relocation and discharge to land

Winton WWTP is decommissioned and relocated to area in close proximity to suitable land disposal fields

 

It is important to factor various constraints impacting the project into consideration, including the following:

• 10 options have been identified for viable cost effective solutions for Winton wastewater
• 5 options of 100% disposal to water have been discontinued due to stakeholder consultation
• 4 options of a combination of land and water disposal have been discontinued due to their dependency on water disposal
• One option has been shortlisted:
  • 100% land disposal and new treatment facility at the existing Winton ponds site
• Te Ao Marama have endorsed the option of 100% disposal to land as the primary option
• The current Winton waste water discharge consent expires December 2023
• The Winton waste water discharge consent application will need to be amended or re-applied for
• Two land packages within the Winton area have been identified that following preliminary investigation, would be deemed suitable for 100% land disposal
• The budget within the Long Term Plan is set at $29.2 million
• The cost estimate is between $27 million and $66 million
• The preferred option is for the land disposal and new treatment facility at the existing Winton ponds site