THE KAWENATA PROPOSAL ABOUT DISCHARGING TREATED WASTEWATER
Reynold Macpherson and Lachlan McKenzie
Rotorua District Residents and Ratepayers
5 February 2021
Executive Summary
Rotorua Lakes Council (RLC) has proposed that, as part of the upgrading of Rotorua’s Wastewater Treatment Plant (WWTP), that the system be extended so that all wastewater is fully treated and safe before it is returned to the environment.
The RLC’s recommended system, known as Kawenata, is to include
- Increasing the capacity and provision for stormwater flow storage
- Removing additional phosphorus (P)
- Ultra-filtration using Membrane BioReactor (MBR) technology to remove Nitrogen (N) and Phosphorous (P)
- The sludge going to Kawerau for composting
- Ultraviolet disinfection technology to neutralize pathogens, and
- Discharging the treated wastewater to the environment over a land contact bed.
RDRR’s members, associates and friends remain strongly of the view that
- the planned upgrades to the WWTP, especially the installation of ultraviolet technology, are critical to restoring the wellbeing of the water, prior to switching over to the relocated land contact bed
- the rigorous measurement of N, P and E-coli at WWTP discharge and stream entry points remain crucial to the achievement of water wellbeing targets – to ensure that Lake Rotorua is swimmable and clear in the future, has a low bacterial content, and is both odour free and life-bearing
- the excessive amount of stormwater entering the wastewater system through aged pipes and misconnections is a major challenge that needs to be addressed with urgency, and
- additional biological methods of further reducing N and P in discharged treated wastewater should be explored urgently to provide commercial opportunities and to sustain preferred wellbeing outcomes.
Background
The Rotorua District Residents and Ratepayers (RDRR), along with most other submitters, unsuccessfully opposed the RLC’s outsourcing of the management of the wastewater system, preferring the retention of profits in the local economy during the Covid Depression, internal capacity building, minimising risk to ratepayers of budget blowouts and avoiding an association (through the ownership of Trility) with a regime that has a repugnant human rights record.
RDRR has supported all parts of the recommended wastewater treatment system above since 2013 except the direct discharge of treated wastewater into Lake Rotorua. Along with over 60 other community organisations, RDRR gained s274 status in the Environment Court to contest the direct discharge of treated wastewater into the Lake on cultural, commercial, and scientific grounds.
It therefore provisionally supports the RLC’s decision to withdraw its application to the Environment Court and its proposal to relocate the land contact bed up into the Whakarewarewa Forest by the water storage ponds (the Kawenata proposal).
RDRR Policy Review
The RLC’s decisions, to withdraw from the Environment Court and to propose moving the land contact bed into the Whakarewarewa Forest, caused the RDRR to conduct a policy review.
It invited the RLC’s General Manager Infrastructure Stavros Michael, accompanied by Gina Rangi, Group Manager Maori, and Reagan Frazer, Deputy General Manager Infrastructure, to brief RDRR members, associates, and friends, on 5 November.
This policy paper was then drafted by Reynold Macpherson and Lachlan McKenzie and shared with all RDRR members with an invitation to suggest improvements. A revised draft was presented to the RDRR’s AGM on Thursday 19 November and endorsed. This fifth and final version therefore stands as RDRR’s policy position.
Cultural Respect and Inclusive Partnerships
Both Māori and non-Māori RDRR members continue to regard any direct discharge of treated wastewater into the Lake as culturally offensive given their shared and deep commitment to environmental values.
They also continue to accept that the proposed land contact bed may simultaneously satisfy mātāpono Māori (Māori values), intercultural environmental values and scientific values. Following the planned installation of MBR and ultraviolet technologies, the land contact bed will help re-oxygenate the water, although RDRR does urge Council to
- boost its capacity to provide for approximately 120,000 people at today’s loading rates for the next 50 years, and
- explore other biological methods of further reducing N and P in treated wastewater before it reaches the streams running into Lake Rotorua.
RDRR members therefore look forward to the RLC
- equally respecting the shared environmental values of all cultures
- bridging ideological and political divisions between legitimate stakeholders on the issue of treating wastewater, and
- returning to rational and consensual policymaking in the public interest which avoids litigation, respects ratepayers as partners, copes with a growing population and achieves rising standards.
Contributions and Commercial Opportunities
RDRR members were disappointed when the RLC announced a premature agreement with Central North Island (CNI) iwi not to continue to use the 400 Ha in the Whakarewarewa Forest for the spray irrigation of treated wastewater. The 400 Ha had an encumbrance on it when CNI bought the land with settlement money.
The RLC has a resource consent in perpetuity to use the land as a wastewater disposal site but had to apply for a new resource consent with Bay of Plenty Regional Council (BOPRC). In effect, the premature agreement allowed CNI to abrogate their legal obligation to allow spray irrigation on the 400 Ha prior to a new system being agreed. It is shown below that spray irrigation has proved broadly successful and must be maintained to sustain the four wellbeings of our community until the changes recommended are implemented.
RDRR members are nevertheless thankful that CNI have agreed to allow the use of 40 Ha of land near the storage ponds for land disposal of wastewater until a new solution is developed. They note, however, that 40 Ha is probably an insufficient area for land treatment of the volume of treated wastewater that the city will generate, even if most stormwater is diverted from the wastewater system.
Ratepayers will have to pay to pump the wastewater the five kilometres from the WWTP to the storage ponds and the proposed land contact bed site. On the other hand, RDRR members see it as a reasonable contribution to help safeguard the quality of Lake Rotorua for cultural, recreational, and commercial purposes by adding the necessary infrastructure.
In scientific terms, land contact beds do not significantly improve the quality of the treated wastewater, other than add a little to the level of oxygenation. Moving the contact bed further away from the lake may help resolve Māori cultural objections and help rectify unfortunate optics in a tourist city. However, RDRR would urge Council to consider additional biological methods of further and measurably reducing remnants of N and P in the discharged treated wastewater prior to it entering streams.
Additional commercial opportunities using biological methods, such as algae farming, water cress and market gardening, and hemp cropping, that will help extract remnants of N and P from treated wastewater, have not apparently been explored. Recycling options also need serious investigation to reduce treatment volumes.
Treated wastewater (that will remain at less than drinking standard) could also be used in commercial activities, such as industrial cleaning (e.g. forestry truck washdowns) and irrigation (e.g.s sports fields, market gardens), and thereby save fresh water for domestic use and reduce the volume of wastewater to be treated and discharged.
The Convergence of Cultural and Scientific Imperatives as Environmental Values
RDRR members are comfortable with the cultural diversity of our community and therefore the different ways in which people can legitimately refer to the health of water. They endorse the RLC’s objective of treating wastewater “to a standard which is life sustaining and restores the mauri (wellbeing) of the water, protects public health and the environment, meets national requirements and satisfies regulatory requirements.”
RDRR members also accept that Rotorua’s legacy of pollution is inconsistent with the wellbeing interests of our community. They support in principle even greater public investment and more effective treatment practices that will sustain the quality of wastewater outcomes for a district population that is projected to grow to about 120,000 over the next 50 years.
More broadly, they acknowledge the long-term initiative taken by central government to explore supra-regional entities to significantly upgrade three waters’ infrastructure across New Zealand. The proposed upgrade of Rotorua’s WWTP will only last about 50 years. They therefore endorse central strategic planning reaching out 50-100 years, the encouragement of innovation, especially in biological methods, and the use of geo-thermal energy.
The BOPRC has spent over 15 years developing nutrient load and pathogen limits for Lake Rotorua. The annual load limits for N and P from Rotorua’s wastewater to the lake are set at 30 and 3 tonnes, respectively. The pathogen limits are set at less than 10 E-coli per 100 millilitres of water.
Treated wastewater currently leaving Rotorua’s WWTP for spray irrigation contains about 60 tonne of N pa and about 20 tonnes of P pa. The WWTP currently does not have any ultraviolet disinfection capacity.
This means that the spray irrigation system currently in use in the Whakarewarewa Forest reduces the N and P loads in the wastewater entering Lake Rotorua to about the limits prescribed by the BOPRC.
However, although exposure to natural light initially reduced the pathogen levels to about the set limits, the trees in the forest have grown and the E-coli levels have risen above prescribed bathing standards.
Conclusions
RDRR’s members, associates and friends remain strongly of the view that
- the planned upgrades to the WWTP, especially the installation of ultraviolet technology, are critical to restoring the wellbeing of the water, prior to switching over to the relocated land contact bed
- the rigorous measurement of N, P and E-coli at WWTP discharge and stream entry points remain crucial to the achievement of water wellbeing targets – to ensure that Lake Rotorua is swimmable and clear in the future, has a low bacterial content, and is both odour free and life-bearing
- the excessive amount of stormwater entering the wastewater system through aged pipes and misconnections is a major challenge that needs to be addressed with urgency, and
- additional biological methods of further reducing N and P in discharged treated wastewater should be explored urgently to provide commercial opportunities and to sustain preferred wellbeing outcomes.
Preliminary Conclusion
RDRR members are strongly of the view that
- the planned upgrades to the WWTP, especially the installation of ultraviolet technology, are critical to restoring the wellbeing of the water, prior to switching over to the relocated land contact bed
- the rigorous measurement of N, P and E-coli at discharge and stream entry remain crucial to the achievement of water wellbeing targets – to ensure that Lake Rotorua is swimmable and clear in the future, has a low bacterial content, and is both odour free and life bearing
- the excessive amount of stormwater entering the wastewater system through aged pipes and misconnections is a major challenge that needs to be addressed with urgency, and
- additional biological methods of further reducing N and P in discharged treated wastewater should be explored urgently to provide commercial opportunities and to sustain preferred wellbeing outcomes.
Contacts:
Reynold Macpherson, 484 Pukehangi Road, 07 346 8553, 021 725 708, reynold@reynoldmacpherson.ac.nz
Lachlan McKenzie, 289 Kapukapu Road, 021 382 442, lachlanm289@gmail.com