Whangārei Wastewater Discharge Consent Renewal

Submissions closing on 05 May 2021, 05:00 PM

Wastewater Treatment Plant community survey

The Whangārei Wastewater Treatment Plant (WWTP) discharge consent is expiring in 2022 and we need to apply to the Northland Regional Council to renew it.


Community Survey

Fill out this customer survey to tell us what issues are most important for you.

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Location

Kioreroa Road, Whangārei 0110  View Map

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We want to talk to you, consider the issues you feel are important, and explore possible solutions.

Our goal is to provide this necessary waste treatment service to the community with the least impact on the surrounding environment. We want to hear your concerns and expectations. Your input will help us as we develop our consent application over the next year.

We will also be involving local hapū and other groups such as Department of Conservation, Forest and Bird, Fish and Game and the Whangārei Harbour Advisory Catchment Group.

If you would like to find out more, or be informed of upcoming public meetings about the consent process please contact Infrastructure Planning Team Leader Sarah Irwin:

Email us: Attn Sarah Irwin

Broadly speaking, the answer is yes - but with more of a focus on the environment. Our goal is to ensure that wastewater entering our environment is improved over the term of the consent.

The maximum amount of wastewater we discharge is expected to stay the same, at 140,000 cubic metres a day. At the moment, we process around 21,000 cubic metres on a normal day but this increases during heavy rainfall.

Part of this consent process is a best options analysis, to make sure we're meeting our obligations under the Regional Plan as well as the National Policy Statement - Fresh Water Guidance. We will also work out any changes needed for improving Whangārei’s wastewater system, such as odour control upgrades.

We are applying for a 35-year consent duration.

The Wastewater Treatment Plant needs to renew its existing consent so that it can legally operate and dispose of effluent into the adjacent air, land and water in a regulated and responsible manner.

Council will also be seeking consent for the wastewater network and pump stations under a separate consent process.

No, untreated water does not go into the harbour from the wastewater treatment plant.

When it rains, extra water enters the wastewater system and the plant struggles to cope with the higher flow. On a normal day, discharged water goes through the full treatment process but during storms this process is shortened. During storms, wastewater (as a minimum) undergoes screening, settlement, disinfection by ultraviolet light and wetland treatment.

Over the past ten years Council has spent $60 million improving water quality in the harbour through a number of successful projects.

In the past, heavy rainfall would trigger sewerage spills into the harbour due to stormwater and groundwater entering and overflowing the wastewater system.

The multi-million dollar projects completed to date include:

  • New storage and treatment facilities at Whareora Rd and Tarewa Park which contain and treat extra water that enters the system during storms
  • Major upgrades to the Wastewater Treatment Plant which means all wastewater receives ultraviolet light and other treatments before being discharged into the wetlands
  • Upgrades to the Okara Park pump station and pipeline
  • Wastewater pipe renewals across the network

These improvements have dramatically reduced the number of sewerage spills into the harbour.

Council has also increased spending on stormwater as part of the 2018-2028 Long term Plan to further improve harbour water quality.

The Wastewater Treatment Plant on Kioreroa Road is largest wastewater processor for Whangārei. It processes an average of 21,000 cubic metres per day of wastewater from homes and businesses and has a replacement value of $65 million.

It  treats wastewater for Whangārei’s main urban area, from Kamo in the north, Maunu in the west, Raumanga in the south to Onerahi and Whangārei Heads in the east.

Cleaning up the city’s wastewater takes a lot of steps – it is strained, mixed, filtered, feasted on by live bacteria, dried and disinfected. The resulting solid waste is taken to landfill and the treated water is discharged into the Limeburners Creek Wetlands.

  • Step 1 – Screening

Wastewater is screened to remove paper and other debris.

  • Step 2 – Separating solids from liquids

Large settling tanks separate the wastewater – the solids (sludge) sink to the bottom and the fats and oils float to the top. The sludge, fats and oils are pumped to sludge digestors while the liquid flows to the basalt rock filters.

  • Stage 3 – Magical microbes

In our basalt rock trickling filters live millions of microbes that eat and digest the organic compounds in the wastewater. This is a 100% natural way to treat wastewater and these bugs are our heroes, doing all the hard work for us without the need for nasty chemicals. These bugs are very susceptible to chemicals which is why it is important not to flush things like paint down our drains.

  • Stage 4 – Superbug soup

The aerators are like two giant eggbeaters – adding oxygen into the wastewater to create a nutrient-rich soup for superbugs that consume microscopic particles in the water. This is the part of the process that causes the smells the plant sometimes produces.

  • Stage 5 – UV treatment

Before being discharged to the wetlands, the effluent is disinfected by ultraviolet (UV) tubes that kill any remaining bugs.

  • Stage 6 - A final filter

The treated water receives a final filter through thousands of native plants in the Limeburner Creek Wetlands. In 2014, the wetlands had a major makeover and instead of the plants being planted in the ground they are now planted on floating mats, their roots extending down into the water. You can explore the wetlands, which provide a great habitat for birds, via a timber boardwalk.

  • The sludge digestors

Solid waste collected during the process is heated and dried in two large digestors which heat it and dry it out. The water that is removed is returned to the waste process and the sludge is taken away to landfill. Two biogas generators harness the poo power created by methane gas during the sludge treatment process and turn it into electricity.

No, this project is already budgeted for as part of the Council’s Long Term Plan 2018-2028.