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Wastewater Projects

Image for the Wastewater Projects page.
 
This page contains information about projects and work we are undertaking to improve the sewerage system in the district.
Updated: 4/09/2020 3:55 p.m.

Our current programme of work includes:

  • upgrading the wastewater treatment plant and wetlands,
  • treating spills at major sites
  • replacing and repairing components of the sewer network to reduce spills.
  • Renewing the Whangarei Wastewater Discharge Consent

We are also working with the Northland Regional Council and others to address wider harbour pollution issues.

Whangarei Wastewater Discharge Consent Renewal

Whangarei’s Wastewater Treatment Plant (WWTP) discharge consent is expiring in 2022 and we need to apply to the Northland Regional Council to renew it. That might seem like a long way in the future but we’re taking the time to do this right, as we know how important this is to the Whangarei community.

Get involved and share your views

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 hapu and other groups such as Department of Conservation, Forest and Bird, Fish and Game and the Whangarei 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:

Our timeline for community engagement

  1. LEARN and ENGAGE via meetings, neighbourhood flyer drops and newspaper articles to gather community feedback on the waste treatment options being proposed.
  2. REVIEW our options based on community feedback
  3. COMMUNICATE the proposed consent application with the public
  4. APPLY for consent to Northland Regional Council by 30 October 2021

Whangarei’s largest wastewater treatment plant

Whenever you flush your toilet, empty your kitchen sink, or do a load of washing – the resulting wastewater needs to be treated and cleaned.

The WWTP on Kioreroa Road is Whangarei’s largest wastewater processor. 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 Whangarei’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.

How does the Wastewater Treatment Plant work?

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

Rotating filters remove any remaining fine particles from the water before it 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.

Why does the WWTP require a resource consent to operate?

The WWTP needs to renew its existing consent so that it can legally operate and dispose of treated effluent into the adjacent air, land and water. Council will also be seeking consent for the wastewater network and pump stations under a separate consent process.

Will the new consent conditions be the same as the current consent conditions?

Our goal is to ensure the current discharge into the environment stays the same or if possible is improved over the term of the consent.

We are not proposing to increase discharges or to change the discharge locations in Limeburners Creek. The maximum permitted discharge volume is expected to stay the same as it is under the current consent at 140,000 cubic metres a day (on a normal day we process around 21,000 cubic metres a day but this increases during heavy rainfall).

As part of this consent process we are carrying out a best practicable options analysis to work out the best way to treat Whangarei’s wastewater, this includes ensuring we meet the requirements of the Regional Plan as well as the National Policy Statement – Fresh Water Guidance.

We are seeking a 35-year consent duration to provide investment certainty for the District’s ratepayers. 

What is Council doing to improve water quality in the harbour?

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

In the past sewer spills into the harbour occurred during heavy rain 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 WWTP which means all wastewater receives UV 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 sewer spills into the harbour and improved harbour water quality.

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

Does untreated water still go into the harbour during storms?

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 extra 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, UV and wetland treatment.

The plant does have a manual bypass that would allow untreated water to go into the harbour during an emergency but this has never had to be used.

Will my rates increase because of this project?

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

 


 

Completed projects

Work has been completed on a number of projects:

  • Hikurangi Sewerage Network Upgrade 2018-2020
  • Morningside flood relief drain
  • Kamo Road sewer upgrade
  • Kensington Avenue/SH1 sewer modifications
  • Lupton Avenue sewer upgrade
  • Waro rising main and pump station upgrade
  • Relining of sewer network in Denby Crescent
  • Five new public toilets constructed
  • Upgrade of internal roads and administration building in the Whangarei WWTP
  • Sewer extension on SH14 to service Maunu Road school
  • Upgrade of telemetry systems so our pump station performance can be monitored eficiently and effectively 24/7
  • Upgrades of ageing equipment at Whangarei WWTP
  • Pump upgrades at some of our critical pumping stations
  • Replacement of the Waverley Street rising main in Onerahi
  • Digester upgrades at Kioreroa Road WWTP
  • Wastewater overflow mitigation

If you would like further information about these projects, please contact us.

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