Christchurch City Council needs to upgrade Akaroa’s wastewater system. The upgrade reflects our commitment to ensure the Akaroa community is provided with a high quality wastewater system.
A new site has been chosen for technical and operational reasons, and recognises the historical importance of the Takapūneke Historic Reserve, where the current plant is located.
The new plant will be a compact modern facility, making use of recent improvements in wastewater treatment and attractively landscaped to limit visual impact. It will be quiet and will not cause odour. This will minimise the new plant’s impact on the environment and the community.
Benefits of the Akaroa wastewater scheme
- Recognition of the historic and cultural importance of Takapūneke Historic Reserve to all New Zealanders and particularly to Ngāi Tahu.
- The modern plant will produce extremely clean treated wastewater which could eventually be used as a non-potable water supply (e.g. for watering public parks and flushing toilets).
- The plant contributes to higher water quality that supports water sports, recreation, tourism and aquaculture in the region.
- The new site is closer to more potentially suitable land for irrigation.
Please email the project team if you have any questions or would like to sign up for our project e-newsletter.
The Council has obtained resource consents for building and operating the new Akaroa Wastewater Treatment Plant on Old Coach Road and a new pump station in the boat park at Childrens Bay, and for upgrading wastewater mains and the three existing pump stations. However, the Council's applications for consents to construct a new pipe outfall to Akaroa Harbour, and discharge treated wastewater via that pipe outfall, were declined, on the grounds that the discharge was offensive to Ngāi Tahu and because the Hearing Commissioners considered that alternatives to the discharge to the harbour had not been adequately investigated. For more information, view the Decision of the Hearings Commissioners(external link).
The Council has lodged an appeal against the decline of those consents but will not be making a decision on pursuing that appeal until it has reassessed alternatives for the discharge.
Lincoln University Trials
Lincoln University has conducted a lysimeter trial where treated wastewater from the Duvauchelle wastewater treatment plant was irrigated onto soil cores taken from the golf course at Duvauchelle and the Takamatua Peninsula.
Lincoln University is also conducting a trial where various native plant species are irrigated using treated wastewater from the Duvauchelle wastewater treatment plant.
The key findings were that wastewater irrigation enhanced pasture growth and tree growth, that treated wastewater could be applied at a rate of 500 - 800 mm per year and that nitrogen leaching was negligible compared to that from grazed pasture.
The final report [PDF, 2.6 MB] is now available.
Consultation on reuse, treatment and disposal options 3 April - 8 May 2017
Consultation has now closed on the options for the beneficial reuse, treatment and disposal of treated wastewater from Akaroa. Dates for the hearings panel will hear those submitters that wish to be heard are yet to be set. The consultation booklet [PDF, 15 MB] summarises the options being considered:
- Irrigation of trees or pasture in Robinsons Bay.
- Irrigation of trees or pasture at Pompeys Pillar.
- Irrigation of trees or pasture in Takamātua Valley, in combination with another area.
- Non-potable re-use in Akaroa, in combination with another option.
- Disposal via a new outfall pipeline to the mid-harbour (the original proposal for which consent was sought).
For the detailed information about the options being consulted on, please refer to the report Akaroa Wastewater Investigation of Alternative Sites for Land Irrigation (CH2M Beca, March 2017) [PDF, 4.2 MB] and its appendices:
- Appendix A - Infiltration Testing Results for Akaroa Wastewater Disposal via Irrigation (PDP, June 2016) [PDF, 4.2 MB]
- appendix B - Preliminary Geotechnical Assessment (CH2M Beca, June 2016) [PDF, 4.1 MB]
- Appendix C - Tonkin and Taylor Slope Hazard Maps [PDF, 10 MB]
- Appendix D - Maps of Potentially Suitable Irrigation Areas from Concept Report (CH2M Beca, May 2016) [PDF, 9.7 MB]
- Appendix E - David Painter Review of Preliminary Land Investigation Report and Response to Review (July 2016) [PDF, 694 KB]
- Appendix F - High Level Land Screening Map [PDF, 2.7 MB]
- Appendix G - Maps of Potentially Suitable Irrigable Area for Alternative Sites (October 2016 criteria) [PDF, 15 MB]
- Appendix H - Outline Scheme Designs [PDF, 12 MB]
- Appendix I - GIS Screening of Pond Storage Locations [PDF, 17 MB]
- Appendix J - Akaroa Wastewater Project - High Level Landscape and Visual Review (Align, March 2017) [PDF, 17 MB]
- Appendix K - Report on Thacker Property Inspection (CH2M Beca, February 2017) [PDF, 3.8 MB]
- Appendix L - Infiltration Testing Results - Robinsons Bay and Pompeys Pillar (PDP, November 2016) [PDF, 10 MB]
- Appendix M - Land Testing of Alternative Sites for Disposal of Treated Wastewater from Akaroa [PDF, 4.9 MB](CH2M Beca, November 2016)
- Appendix N - Infiltration Testing Results for Thacker Land (PDP, February 2017) [PDF, 7.1 MB]
- Appendix O - Thacker Site Robinsons Bay - Geotechnical Report (CH2M Beca, February 2017) [PDF, 5 MB]
- Appendix P - Planning Overlay Maps [PDF, 4.9 MB]
- Appendix Q - Cost Estimates [PDF, 790 KB].
Akaroa Treated Wastewater Reuse Options Working Party
At the meeting on Monday 30 January, the Banks Peninsula Community Board received a Community Strategy Toward an Acceptable Solution to the Disposal of Akaroa Wastewater, prepared and adopted by the community of Robinsons Bay and adopted by Friends of Banks Peninsula. This included a request that Council takes a collaborative approach with the community on this project and that public consultation is delayed until April to allow this to occur.
In response to this, the Board resolved to establish a Working Party to collaborate with the community and engage on community concerns about the Akaroa Treated Wastewater Disposal Project, and to delay any further consultation on the project until April 2017.
The Community Board prepared terms of reference for the working party [PDF, 32 KB]. The notes from each of the working party's meetings are as follows:
The working party prepared a joint statement [PDF, 2.9 MB] and which summarises the matters which the working party members agreed and disagreed on.
Akaroa Wastewater Technical Experts Group
The Akaroa Wastewater Technical Experts Group consists of experts working for the Council, the Friends of Banks Peninsula and Ngāi Tahu.
The terms of reference for the Akaroa Wastewater Technical Experts Group [PDF, 27 KB], their first joint statement [PDF, 88 KB], second joint statement [PDF, 197 KB] and third joint statement [PDF, 1.1 MB] are available.
Previous investigations and consultation
The Council has been working with Ōnuku Rūnanga, Wairewa Rūnanga, the Akaroa Taiāpure Management Committee and Te Runanga o Ngāi Tahu (the Ngāi Tahu parties) and the community to explore land-based alternatives to the harbour outfall.
In 2016 the Council considered six options for disposal of treated wastewater:
- Year-round irrigation to trees.
- Year-round irrigation to pasture.
- Summer-only irrigation, with a wetland or infiltration basin and discharge via a coastal infiltration gallery at other times.
- Subsurface flow wetland and discharge via a coastal infiltration gallery.
- Infiltration basin and discharge via a coastal infiltration gallery.
- Outfall pipeline to the mid-harbour (being the one applied for).
A desktop study was undertaken in May 2016 to identify possible areas for land treatment options. The following criteria were used:
- not too far from the new wastewater treatment plant on Old Coach Road (a two kilometre radius was used), relatively flat (less than 15 degree slope)
- at least 25 metres from a residential area or waterway
- property size of at least 1 hectare
- not known to have land stability issues.
All of the areas identified as possibly suitable for irrigation were on Takamātua Peninsula or in the Takamātua Valley and are in private ownership. Options for access to the needed land are purchase, lease or license. Several of the options required discharge of remaining wastewater in a diffuse way on the coastline, most likely via a coastal infiltration gallery at the end of the Takamātua Peninsula.
Ngāi Tahu strongly supports the options of year-round irrigation to trees and pasture, as they are consistent with their cultural values. The options involving a diffuse coastal discharge were not supported by Ngāi Tahu, as they do not use natural processes to restore the mauri of the wastewater, and continues discharge of it into the harbour. View the Akaroa Treated Wastewater Disposal Options Consultation Booklet [PDF, 1.2 MB] for a description of each of the options that were considered in 2016, and their advantages and disadvantages.
For more detailed information on each of the options considered in 2016, please see the Akaroa Wastewater Concept Design Report for Alternatives to Harbour Outfall (CH2M Beca, May 2016 [PDF, 3.8 MB]) and the appendices to the report:
- Appendix A - Overview of Scheme in Consent Application [PDF, 203 KB]
- Appendix B - Peer Review and Response to Peer Review [PDF, 1.1 MB]
- Appendix C - Hydrogeological Report [PDF, 3.4 MB]
- Appendix D - Area Overview Drawing [PDF, 1.1 MB]
- Appendix E - Location Maps [PDF, 9.7 MB]
- Appendix F - Geotechnical Figures [PDF, 460 KB]
- Appendix G - Planning Maps [PDF, 9.4 MB]
- Appendix H - Resource Consents Required [PDF, 38 KB]
- Appendix I - Disinfection Through Wetlands [PDF, 86 KB]
- Appendix J - Wainui Wastewater Scheme Monitoring Reports [PDF, 925 KB]
- Appendix K - Environment Canterbury Review [PDF, 165 KB].
The Council sought public feedback on these options between 26 April and 12 June 2016. View the questions and answers from the consultation meetings, and the submissions and project team responses:
Following the public consultation, the Council commissioned preliminary geotechnical investigations, including test pits and infiltration testing on some of the possible irrigation sites at the end of May 2016, and a cover letter [PDF, 1.7 MB] and two reports were received (see appendices A and B of the CH2M Beca report below for the reports). The cover letter highlighted the risk of exacerbating instability where the slopes downhill of the irrigation area are steeper than 15 degrees, and their recommendation was that we avoid irrigating those areas.
These land investigations found that Takamatua Peninsula and Blocks F and H are not suitable for irrigation of treated wastewater and so the Council is no longer considering these locations. This meant that there was a risk that insufficient land would be available for irrigation and so the Council decided to consider land that may be suitable for irrigation further afield. The areas that met the revised criteria in the wider area were Takamatua Valley, Robinsons Bay and Pompeys Pillar.
Options 3 to 5, which included a wetland or infiltration basins and a coastal infiltration gallery on the headland of Takamātua Peninsula, were not supported by the community or the Ngāi Tahu parties, so the Council is not considering these options further until land based options have been more fully investigated.
Consultation Meetings November - December 2016
A public meeting was held at the Gaiety Hall on Wednesday 9 November and a presentation [PDF, 4.9 MB] was given to explain why the Council is exploring alternatives to a harbour outfall for treated wastewater disposal, how these three areas were selected, and to provide the results of land investigations for areas that may be suitable for irrigation of treated wastewater. View the questions raised at the meeting and the answers from the project team [PDF, 95 KB] [PDF 96KB] and responses to questions tabled at the meeting by the Robinsons Bay community [PDF, 174 KB].
A community consultation workshop was held at the Gaiety Hall on Saturday 3 December. The community provided responses to four questions; see below for photos of these responses:
Further background information
For further background information, there are also three historical reports that explored wastewater options for Akaroa:
The proposed Akaroa wastewater scheme in the consent application included
- Replacing the existing trunk pipelines, upgrading the existing pump stations, and constructing a new terminal pump station to pump flows to the new treatment plant.
- A terminal pump station to be located in the Akaroa boat/trailer park, which will incorporate fine screens and grit removal, to protect the progressive cavity pumps and to provide primary treatment.
- A new biological nitrogen removal (BNR) membrane wastewater treatment plant located at the site on Old Coach Road, providing a higher quality treated wastewater. The treatment process will likely be the Modified Ludsak-Ettinger (MLE) process, although other alternatives proposed by tenderers will be considered. Solids separation and disinfection will be provided by membrane filtration. High flows will bypass the main treatment process, and will receive ultraviolet (UV) disinfection before being discharged into the outfall pipe. The design of the treatment plant has taken into account the seasonal population by including two parallel treatment trains so that capacity can be increased as needed during peak summer flows, and has been designed to provide full treatment for the peak summer population in 2041. Note that bypass treatment is no longer proposed and that all wastewater will receive full treatment.
- A new polyethylene discharge pipeline along Old Coach Road Treated to the start of a new harbour outfall at Childrens Bay, so that treated wastewater can flow by gravity from the new treatment plant to the outfall.
- A new 2.5 km long polyethylene (PE) harbour outfall pipe will extend from Childrens Bay, with a diffuser located at 9.5 m depth.
- Decommissioning the existing wastewater treatment plant on the Takapūneke Historic Reserve.
The whole project is estimated to cost about $30 million, including the new treatment plant, new harbour outfall, new terminal pump station and upgrades to the existing pump stations and pipeline that runs through Akaroa.
Akaroa Wastewater Scheme Map