Late Reports Agenda of Wastewater Management Review Committee meeting

Wastewater Management Review Committee meeting Agenda

17 March 2026

9 Business

9.1 Wastewater Activity Report

File Number: A19836768

Author: Jim Summers, Environmental Programme Leader

Authoriser: Reneke van Soest, General Manager: Operations & Infrastructure

Purpose of the Report

1. To provide information to the Wastewater Management Review Committee (WWMRC) on the status of the wastewater networks and associated projects.

Recommendations

That the Wastewater Management Review Committee:

(a) Receives the report "Wastewater Activity Report".

discussion

Wastewater Resource Consents

2. Monitoring results for Councils wastewater consents are all within consent requirements. This includes discharges from the outfall at Te Maunga.

3. Following the submission of the Monitoring Upgrade and Technological Review (MUTR) to the Bay of Plenty Regional Council (BoPRC), staff have yet to receive any feedback or comments on the document.

4. Staff are continuing to work with tangata whenua on a draft kaitiaki monitoring plan and proposed baseline monitoring recommendations. Marearea are also working on a report on the effectiveness of the consent conditions in relation to cultural values.

5. These pieces of work will be available for staff to review soon, with a workshop proposed to be held prior to the next committee meeting for a more in-depth discussion on this work and the other recommendations in the MUTR report.

6. Attachment 1 includes a summary of recommendations from the previous and latest MUTR reports.

Wastewater Overflows

7. Since the previous committee meeting there have been 31 blockages that have been notified to council. 27 did not leave the network and were contained to land and 4 potentially made the receiving environment. These were all notified to BoPRC, Toi Te Ora and local hapu/iwi RMA reps. Water quality sampling was undertaken, and warning signage placed in the relevant areas until results indicated no further impacts on water quality.

RC62722 & RC62723 - Te Maunga & Chapel Street Odour

8. No odour complaints received for Chapel Street or Te Maunga Wastewater Treatment Plant (WWTP).

Clarifier 3

9. Physical works and preliminary commissioning completed. The final commissioning will be carried out when Bioreactor 2 is completed.

Bioreactor 2

10. Construction is progressing well with expected completion date towards the end of 2026. The final commissioning will follow construction; this is expected to be in service early 2027.

Bioreactor 1

11. Advance ordering of long lead materials will commence April 2026.

12. Once Bioreactor 2 is in service, Bioreactor 1 will be taken off-line and drained (circa March 2027).

13. This will enable the equipment inside the bioreactor to be replaced. The project is expected to take 3 months.

New Inlet Works (NIW)

14. Preliminary Design has been completed and reviewed. Next design phase is scheduled to commence in April 26.

15. Construction is scheduled for July 2028.

Opal Drive Wastewater Pumpstation

16. Works are progressing well with the new pump station expected to be operational by June 2026. An unexpected intact archaeology find has halted works in a small area of the site while an authority to proceed is sought from Heritage NZ

17. Once the new pump station is fully operational the existing pump station will be demolished, with that part of the site returned to mown grass.

Wairakei Wastewater Pump Station

18. Design is complete and physical works are currently being priced by the contractor

19. The BoPRC resource consent is currently on hold pending further engagement between TCC and Ngā Potiki.

Wastewater Network - Operation

20. Since the last committee meeting, the Wastewater Renewals team has continued to deliver significant wastewater pipe relining works across the city. Relining remains an efficient and cost-effective solution, extending the life of assets while minimising community disruption compared to full replacement.

21. In addition to relining, dig-and-relay works are in progress in Mansels Avenue, and Totara South. Reactive maintenance activities have also been carried out across the wider network to address issues and maintain service continuity.

Environmental Mitigation and Enhancement Fund (EMEF)

22. There have been no changes since the previous committee update. The fund remains at approximately $850,000, and staff are available to support Tangata whenua members when they choose to progress the guideline review.

Wastewater Programme Business Case (PBC)

23. The Wastewater Programme Business Case (PBC) was initiated to define future investment in the marine outfall but was subsequently broadened in scope to consider investment in the treatment plants and wider network. A project team (including Iwi and Hapū representatives) has been established for some time and have been working through the PBC (utilising Treasury’s Better Business Case framework). The PBC process involves defining key matters to be addressed within the wastewater scheme, the development of future investment and proposes possible options or responses which could be implemented to address to these issues.

24. Following WWMRC endorsement of initial-stage outputs in early 2024 (ILM, benefits, investment objectives, key service requirements (KSR’s) and critical success factors (CSF’s)), and long list identification workshops with the Project Team in May and June 2024, technical work to identify those studies required to inform the assessment of a long-list has been completed.

25. The scope and KSRs describe the degree or scale of change required for the programme to be considered successful. The broad scope of the PBC is reflected in a comprehensive set of KSRs, spanning themes of growth and development, tāngata whenua partnership and values, protecting and enhancing the environment, and resilience and adaptability – they are the key requirements for any investment. The long list of options are those responses potentially capable of achieving the KSRs and will be assessed by the Project Team against the CSF’s and investment objectives to achieve a short-list.

26. Key to the technical work recently completed has been understanding in more detail the Growth and Development Servicing KSR (geographic areas/populations) which includes consideration of servicing within the Western Bay of Plenty District where it makes sense to do so.

Growth Servicing Study

27. This work, termed a ‘Growth Servicing Study’, provides further definition to two high-level approaches identified by the Project Team; these approaches being, to either maximise treatment and storage at the Te Maunga WWTP site, or to limit expansion at Te Maunga to a (to be defined) point (the later approach would see some or all new, and potentially existing, development serviced by new WWTPs).

28. The Growth Servicing Study has provided this definition by modelling a range of growth servicing options (Options 1-7A/B + 8 as depicted in the table below) considering population growth to 2100 and utilising the two existing wastewater treatment plants at Chapel Street and Te Maunga, and also the addition of one or more wastewater treatment plants in other fringe areas of the City. These ‘Configuration and Scale’ options consider growth, the location of this growth, network constraints (including timing for when these constraints appear), and outfall system capacity (i.e. availability of ponds for flow balancing and impact on marine outfall sizing).

29. Although meeting key geographical scope and population growth requirements is central to these options, other KSRs directly influence the Configuration and Scale of a future wastewater system. The long-list options therefore directly incorporate relevant aspects of the following KSRs:

● KSR 3: Giving greater effect to Tāngata whenua cultural values - variations of either reduced, or ceased, use of the Te Maunga ponds for flow buffering into all options

● KSR 4: Incorporating Tāngata whenua partner perspectives by exploring options that divert selected existing catchments and/or planned new developments away from existing TCC WWTPs and existing discharge locations

● KSR 19: Resilience to natural hazards, through key asset location options that reduce reliance on sites prone to natural hazards (including climate change effects)

● KSR 20: Operational resilience (with a flexibility lens), through diversification of WWTP locations (and associated receiving environments or reuse applications)

● KSR 21: Key Asset resilience, through replacement of the existing Te Maunga marine ocean outfall with a resilient material

30. Refer below for an example graphic depicting study outputs for Option 1A

31. The Growth Servicing Study is now complete, with its findings included within a completed draft Wastewater Programme Business Case report which includes the full Strategic Case and the Economic Case up to and including identification and compilation of long-list programme options. Staff have recently completed a review of the draft document and intend to provide an update on this and proposed next steps to the new GM Infrastructure and Operations and General Manager: Strategy, Partnerships & Growth to ensure alignment of PBC against current growth planning needs. Following the GM briefing it is anticipated that the PBC project team, including Iwi and Hapū representatives, will reform to first review the draft long-list Configuration and Scale options, and subsequently undertake an assessment of those options to identify a short-list, including the preferred way forward. A costing study of all Configuration and Scale long-list options will also be carried out to define the high-level costs of each to inform their affordability.

Indicative Programme for Next Steps

32. An indicative programme for this next tranche of work, likely to take between 8-12 months, is as follows:

	Project Team	WWMRC
April-May	- Workshop: Reset - Workshop: Long-List Configuration and Scale Options - Issue of Draft (interim) PBC report for information
May-June		- Issue of Draft (interim) PBC report for information (if desired) - Workshop: PBC Introduction - Meeting: Confirm Long-List Configuration and Scale Options
June-August	- 2 x Workshops: Long-List Assessment
August-October	- Workshop: Short-List Configuration and Scale Options
October-November		- Meeting: Short-List Configuration and Scale Option Endorsement
November-December	- Issue of Draft PBC report for feedback	- Issue of Draft PBC report for feedback

33. At the completion of short-listing, the PBC report will be updated and work again placed on hold to enable a new Water Organisation, if this decision is made on 2 April, to consider the PBC and short-list and advise any next steps with respect to the PBC.

Biosolids Alternative Disposal Technical Assessment

34. Tauranga currently sends 100% of biosolids produced from its Chapel and Te Maunga WWTPs to vermicomposting. The only current back-up option available to vermicomposting is sending to landfill out of district costing approximately 50% more per tonne for disposal. The long-term future cost of vermicomposting disposal has some risk as it relies on sufficient supplies of cheap organic media from for example pulp and paper processes and this source is reducing due to recent mill closures. Like other land application processes, changing legislation could also be a risk fo current disposal methods. Landfilling is expensive and has it’s own uncertainty with biosolids in some locations having been rejected or requiring further treatment (and significant capital investment) before acceptance.

35. To address these risks, work is underway on a Biosolids Alternative Disposal Technical Assessment, the objective of which is to determine what near-term next steps should be taken which would enable a range of future disposal options to be considered if vermicomposting becomes no longer available.

36. To meet the requirements for various end use disposal options the quality of biosolids must be compared to the recently released Water Services (Wastewater Environmental Performance Standards) Regulations 2025 which sets out the approach for grading biosolids, how specific grades of biosolids can be safely used, and establishes restrictions for biosolids with a lower grade. Biosolids are given both a stabilisation grade (A or B), and a contaminant grade 1 or 2. Grade A equates to high stabilisation requiring pathogen reduction processes with Grade B low to moderate stabilisation. Contaminant grades reflect contaminant levels with Grade 1 meeting strict thresholds for wider reuse, and Grade 2 requiring specific resource consents.

37. Limited testing completed over 2022-2024 indicates that Chapel Street biosolids may be a B1, and Te Maunga is unclassified (does not meet either A or B grades), contaminant grade 2, however further long-term testing is required to confirm. If confirmed, these classifications would mean that consent must be granted for land application of Chapel Street biosolids (subject to various criteria) but for Te Maunga a stricter consenting pathway exists, meaning that consent may not be granted or if granted, the conditions imposed may be too onerous to meet.

38. Due to the potential differing stabilisation classifications and to enable the full suite of long-term disposal options to be considered, (e.g. land application and thermal treatment options) we are investigating the potential for anaerobic digestion at Te Maunga. The next tranche of work will focus on undertaking a high-level evaluation of costs and benefits, such as the potential to defer other infrastructure and potential for reduced odour, energy and transportation costs. This will involve at the outset further monitoring of biosolids to confirm the classification of biosolids produced by each WWTP.

39. A further update to the WWMRC on this work will be provided at the next WWMRC meeting in June.

Attachments

1. MUTR Discussion Summary - Attachment 1 - A19911148 ⇩


AGENDA Late Reports Wastewater Management Review Committee meeting Tuesday, 17 March 2026

Date:	Tuesday, 17 March 2026
Time:	1:00 pm
Location:	Tauranga City Council Chambers L1, 90 Devonport Road Tauranga
Please note that this meeting will be livestreamed and the recording will be publicly available on Tauranga City Council's website: www.tauranga.govt.nz.
Marty Grenfell Chief Executive