Darfield and Kirwee Wastewater Pipeline Project
Darfield and Kirwee are two of the largest communities in New Zealand without a reticulated wastewater (sewerage) system. Currently, residents and businesses in Darfield and Kirwee manage their own wastewater, relying on septic tanks and on-site treatment plants.
The existing approach to wastewater discharges (on-site and to ground) has been identified as a potential risk to public health in the long-term and a limitation to growth of these communities.
To reduce any potential risk to human health or the environment, and to better provide for the ongoing population growth that both Darfield and Kirwee are experiencing, the Council is constructing a new wastewater system to service these townships.
This wastewater system will collect the sewerage from both Darfield and Kirwee townships, and pipe it to the existing Pines Wastewater Treatment Plant (WWTP) in Rolleston for treatment.
The project is part of the Council’s Long-Term Plan 2021-2031 and the Council successfully applied for $10.66 million of government funding for this project as part of the post COVID-19 Water Stimulus Package.
Where is the pipeline going to be built?
The pipeline is 26.5km long and begins south of Darfield and ends at the Pines Wastewater Treatment Plant (WWTP) on Burnham School Road, Rolleston. A pipeline from Kirwee will also be constructed, connecting to the main trunk at the junction of Courtenay Road/Miles Road. The pipeline will be located within the road reserve (between the road and private property boundaries). The route is shown on the online project map below which shows the progress made.
Latest road works summary
Current works (note that all completion dates are approximate depending on weather):
- Now pipelaying is complete crews will be working on the final tidy up of work areas. With warmer temperatures our contractors will be completing final reinstatement of the berms and roads which will require temporary traffic management with stop go’s or traffic lights in those locations. All of these are expected to be short term.
Project progress snapshot
Project update - 8 November 2022
All the pipeline for the scheme has been completed with final reinstatement reaching completion across the project. This includes seeding, rolling and mowing berms, texturizing roads, and general tidy up. All these works will be managed using temporary traffic management where required and we appreciate you following the signs to ensure safety of yourselves and our site staff.
Remaining work on the scheme relates to completion of the Darfield and Kirwee Pumpstations which both have the supplies required to be completed.
- The Darfield Pump station is on track to be operational in early December with works underway including final fit outs and preliminary testing.
- The Kirwee Pump station is on track to be operational prior to Christmas break and the current works include building back up the land from the large excavation for wet wells. Following this the above ground fit out will be underway.
Key facts and figures
- 34L/s of flow with the current population of 4,373 people
- >120L/s of flow is expected in the future when population is projected to exceed 13,000 people
- 27.3km of pipeline laid
- 54 manholes installed
- 1000KPa of pressure that the pipeline is designed for
- 2 pumpstations to be built
- 8m the depth of the deepest excavation for the Darfield pumpstation
- 6 of the 7 pipeline sleeves installed below the state highways and rail lines using pipe ramming. The last is for a future water pipe at SH1 pending ground investigation.
- 51 full time equivalent jobs directly involved in the project
- Approximately 20,000 m3 of material was screened onsite and reused rather than imported from quarries
- Up to 7 work fronts are currently working across the project to install the pipeline
- 114m the highest length of pipeline installed in a single day
- 72,862 site hours completed
- 27,300m of pipeline supplied
Frequently asked questions
How long will construction take?
The construction of the main pipeline to the Pines wastewater treatment plant is planned to begin in August 2021 and be completed by July 2022 for Darfield and August 2022 for Kirwee. To see the latest progress on the construction of the pipeline, check the map above.
Will my property be affected by the construction?
The Council and its contractors will maintain access to your property throughout these works but please contact us if you have any specific concerns.
There will be no disruption to your mail delivery or existing services, such as water, wastewater and storm water during the construction of the pipeline.
If your property is directly affected by works you can expect to receive a works notice from SDC’s contractor prior to starting.
Information on the latest road works for the project can be found below.
I have requirements for my home or business that I would like to know if they can be addressed
We are aware some of these roads are utilised for specific needs, such as moving stock or business access, and in most instances we expect to be able to accommodate specific needs.
Please contact us if you have any specific needs and wish to enquire how these will be addressed.
What’s the plan for properties connecting to the new pipeline?
The new pipeline will service both Darfield and Kirwee townships. Properties will connect to the pipeline in the following stages:
Stage 1 (starting August 2021): Complete the pipeline to the Pines wastewater treatment plant and require all new developments in Darfield and Kirwee to connect. Construct the sewer pipeline along the main street in Darfield in 2022/23, with businesses connecting from 2023/24.
Stage 2 (2021–2023): Together with Environment Canterbury, gather information on the current status of consented septic tanks. This will help inform the timing of the connection rollout. The Council will also review how the scheme should be funded.
Stage 3 (2025–2030): Construction of the local pipework to allow connections in higher risk areas of Darfield and Kirwee townships, such as areas with unconsented septic tanks.
Stage 4 (2031–2035): Construction of the local pipework to allow connections in lower risk areas of Darfield and Kirwee townships, such as areas with more recent consents for septic tanks.
When the project finishes work on my road how will it look?
SDC intends to reinstate areas that have been worked on to how they were before. For example, in areas where grass berms were trenched the contractors will shape the berm to return a similar profile, then remove large stones and wood that may be present, before seeding the berm. SDC’s contractors will also be using water carts to help the grass to strike quickly over the summer months.
If you have any concerns related to the reinstatement please get in contact with us.
Why have you closed Courtenay Road in Kirwee?
Courtenay Road, south from Kirwee, is now closed to allow installation of the Darfield to Kirwee wastewater pipeline under the rail line and it will stay closed for about 6 weeks, ie until early September. The closure affects the part of Courtenay Road between the highway and just south of the railway line and means drivers living to the south need to detour via Bealey Road. The pathway is accessible for use by cycles and pedestrians. Measures are also in place to provide access for emergency vehicles.
Council apologises for the considerable inconvenience, but the closure is unavoidable. It is needed because running pipe under the railway line can't be done by digging a trench. It requires a trenchless method, and running the pipe through a steel sleeve, this allows the rail to remain operable throughout. Two pits have to be excavated one on each side and an hydraulic rammer will then be used to push the sleeve through, with pipe dragged through after that. In all, three sleeves need to be installed within the road, one a water supply line and two wastewater pipes, and this takes up a lot of space.
Our contractors explored alternatives to full closure, including whether a lane could be kept open. But this has not been possible because of the large excavations required, the need to maintain space between the services, and the need to keep workers and the public safe. Fully closing the road also means the work can be done faster.
History of the project
History and past reports
In the 2017/18 Annual Plan the Council signalled that a joint working party involving representatives from the Council, the Malvern Community Board, the Darfield and Kirwee Township Committees, Canterbury District Health Board and Environment Canterbury would further consider options for the possible establishment of a wastewater scheme for Darfield and Kirwee, which do not currently have a reticulated wastewater system.
The Council undertook a business case for the scheme, including consultation with Darfield and Kirwee residents in 2019.
Following this, the Council voted in February 2020 to progress work on a wastewater scheme for Darfield and Kirwee.
The Council agreed that there was sufficient evidence to support planning for a wastewater scheme in central Darfield. Further consultation on a possible system for central Darfield and developments in the township was part of the consultation for the 2020/21 Annual Plan. The Council confirmed it would continue to seek cost-effective and environmentally sound solutions for both the Darfield and Kirwee communities.
In December 2020 the Council was granted $10.66 million of funding from the Department of Internal Affairs for the project as part of the three waters infrastructure stimulus funding post-COVID-19.
In the Long-Term Plan 2021-2031 the Council included further consultation on the proposal for the wastewater scheme. In response to feedback from the public it agreed to continue with the proposal, constructing the scheme for all new developments and for the central business area in Darfield, and to review the costs and timeline for existing homes to connect to the to the scheme.
The following documents have been previously commissioned and are available for download.
- Preliminary Report on the Issues and Options for Land Treatment and Disposal of Sewage from Darfield 1996
- Modelling impact of Darfield and Kirwee Wastewater Discharges on Groundwater Quality 2011
- Existing onsite wastewater treatment systems assessment in Darfield 2014
- The Potential Hazard On-Site wastewater Treatment Systems in Darfield and Kirwee 2014 (and Appendices)
- Public health risk assessment of sewage disposal by onsite wastewater treatment and disposal systems in the Darfield and Kirwee Communities 2014
- Darfield Wastewater Strategy 2016
- Darfield and Kirwee Wastewater Strategy 2017
- Darfield Public Meeting Presentation 2019
- Darfield Wastewater Case for Change
- 2021 Groundwater Monitoring