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Wastewater management options

Council continues to be committed to complete the wastewater treatment plant upgrade to improve water quality in Tūranganui-a-Kiwa / Poverty Bay.

Our wastewater goes to the city's wastewater treatment plant where it's screened. It's then treated through a biological trickling filter breaking down the solids to biomass, such as snails, worms and plant like material, then pumped to the outfall pipe in the bay. The treatment plant can receive and treat up to 33,000m3 of wastewater per day.

Our wastewater treatment plant, constructed in 2010, was the first step in improving the quality of treated wastewater pumped through the outfall pipe into the bay. A condition of our resource consent requires Council to implement further treatment, investigate options for alternative use and disposal of our wastewater, and to make every effort to meet cultural objectives to stop discharging into the bay.

In 2017 our Long Term Plan (LTP) pre-consultation included 5 potential wastewater management options. A preferred option was adopted by Council in the 2018-2028 LTP. This option comprises of clarification (removal of solids) and UV treatment of wastewater, with a wastewater wetland constructed once an affordable, sustainable and viable use for the treated wastewater is identified – this is known as Alternate Use Disposal (AUD).

The quality of the discharge into the bay will be further improved when capital improvements to remove solids (clarification), and the treatment of wastewater with UV disinfection are completed in 2022. Council further decided in November 2020 to buy adjacent land in Banks Street for the wastewater treatment plant extension, from Gisborne Holdings Ltd.

The 2018 LTP option adopted by Council was not compliant with the timeframes in the consent.

Based on recommendations from the Wastewater Management Committee (WMC) and further information from Council staff, Council decided in February 2019 to bring forward the project to reduce this consent compliance risk and meet the community’s expectations.

The plan is to start with construction on the wastewater UV disinfection plant this year to further improve the water quality. While this is excellent news, our long-term goal is to remove all household waste from the bay.

Building a wetland, a land-based disposal of wastewater, is the best way to do this. A wetland is a natural ecosystem that will treat and remove contaminants from the water. In the future it could even be stored and used sustainably for farming and horticulture.

We’re actively exploring these wetlands in partnership with key stakeholders, including work with the iwi representatives from the WMC and KIWA Group to progress the use of treated water.

The removal of mortuary waste from the conventional wastewater stream is seen as essential to eliminating perception and cultural barriers to the future use of the treated wastewater. Staff have started early discussions with key stakeholders. The separation of mortuary wastewater will also include a revised Trade Waste Bylaw.

The construction of a wastewater wetland

The construction of a wastewater wetland will proceed once an affordable, sustainable and viable use for the treated wastewater is identified. During this 2021-2031LTP process we’re consulting with the community on how and when this should.

Council’s preferred option is to start the investigation and the detailed design of the city wastewater wetlands, followed by the purchase of land in 2030, with the building of the wetland commencing in 2032. The wetland would help reduce the effects of climate change and help us to adapt to it. Doing it this way means we don’t have to borrow as much and would only be spending $1.8m within this LTP cycle. It will have a minimal impact on rates (0.1% per year) while staying on target to complete the project in 2035.

The alternative option we’ve put out to the community is to fast-track the construction of the wetlands, and start earlier in 2029. The project would be completed sooner but we would need to increase debt funding to $11.4m and it will mean a greater rates increase (1.5% per year).

How it's paid for

We’ve budgeted $21m in year one of the LTP (2021/22) to complete the upgrade for the Gisborne city’s treatment plant, which will improve water quality by removing solids and providing UV treatment before disposal.

A further $2.6m was budgeted for the city’s wastewater wetland (2029 – 2031 and funded by Council and external grants) and $1m for Te Karaka wastewater pond (funded by Council).

The budget is 100% Council funded. Applications for funding to advance alternative use and disposal (AUD), and wetland construction, had been unsuccessful to date.