Akaroa Water Strategy
The future for drinking water and wastewater around the Akaroa harbour basin.
Akaroa Harbour
Background
The Akaroa Harbour basin is unique in New Zealand in that it suffers from water shortages in some settlements around the harbour during summer and some settlements discharge their treated wastewater into the sensitive and enclosed harbour waters.
The Council and the community have an opportunity now to consider all the water issues around Akaroa in a coordinated manner. To achieve this, the Council is developing a water strategy focusing on Akaroa and the Takamatua area.
What happens now
With the exception of Wainui, all the harbour settlements’ water supplies are taken from streams that flow into the harbour. These water supplies are all treated. Low flows in these streams in summer mean that, in Akaroa township for example, water restrictions have to be imposed. While Akaroa also has a very small well supply, most of its water comes from the three streams that flow through the township and into the harbour.
The treated sewage (wastewater) from Akaroa, Duvauchelle and Wainui is discharged into the harbour through outfall pipes. The treated wastewater from Tikao Bay is irrigated onto a small forest block (called a land disposal system). A new treatment plant and land disposal system is also planned for Wainui, and this treated wastewater will also be irrigated on to a forest block. The new Wainui system will be completed by 2010. Other harbour basin settlements and houses have individual septic tanks on each property. The discharge from these septic tanks finds its way into streams and into the harbour.
Akaroa trickling filter
Wider water strategy
Development of this strategy has started. The Council’s consultants, MWH Ltd, have prepared, or are preparing, reports on Akaroa township that address issues and provide information on and options for the following areas:
- Water resources availability
- Water demands
- Water efficiency measures
- Water supply and treatment options
- Reticulation options (including a system model)
- Wastewater treatment and disposal options
Further work is required in each of these areas, however, these reports provide a sound base of information on which future options can be evaluated and decisions made. A brief summary of these reports follows:
Water resources availability
This report identifies the range of existing and potential water sources in Akaroa, Takamatua and further afield, that could contribute toward an integrated water management strategy. The sources identified are additional surface water, storage options, desalination, and wastewater reclamation and reuse.
Water demands
This report establishes a baseline for the present and future requirements of the Akaroa and Takamatua water supply by identifying existing demands, and population growth demands.
Water efficiency measures
This report identifies a range of existing and potential ways to reduce water demand, that could become part of the integrated water management strategy. Reducing demand enhances reliability of the existing water supply. It could also mean a reduction in the amount of money that may need to be spent in future on increasing capacity of the water supply. Therefore, management of demands is closely linked to future water supply requirements.
Water supply and treatment options
This report considers various options for securing a sufficient amount of water to meet the long term demands of Akaroa, makes recommendations, and also suggests short and medium term measures to help achieve the long term strategy.
The report presents practical options for water supply and treatment, for consultation with stakeholders, based on findings from an initial desktop study. After consultation, detailed investigation of the preferred options will commence.
The existing treatment plant is old and in need of a significant upgrade to ensure water reliably meets the New Zealand drinking Water Standards. The report notes that any work to alleviate the Akaroa water supply issues should include the plant upgrade.
One of the key recommendations in the report is that the Council implement a water supply strategy in Akaroa and Takamatua that has a three fold approach, in that it firstly protects the existing run-of-the river stream sources, secondly realises the potential for a new source i.e. the Takamatua north stream, and thirdly considers using reclaimed wastewater for non-potable (non-drinking) uses.
Reticulation options (including system model)
A model of the existing reticulation system has been completed While the existing system is unlikely to significantly influence the development of water management scenarios, the model will be used to identify the most cost effective way of improving pressure and flow in areas that have a substandard level of service.
Wastewater treatment and disposal options
This report identifies future demand for wastewater treatment and options for disposal of treated wastewater, along with the treatment plant upgrades required for those disposal routes. Two primary options have been identified. These are treating wastewater to a higher standard and continuing to discharge it to the harbour, or discharging treated wastewater onto land. Combining these options is also possible in which, for example, treated flows could be applied to land during dry weather, and treated flows only discharged to the harbour during wet weather. Another option that has not yet been given significant attention is the possibility of discharging treated wastewater out to sea, through a long ocean outfall to a point outside the harbour heads.
Immediate wastewater issues
Short-term wastewater consent application
The discharge consent permitting the discharge of treated wastewater from Akaroa township into the harbour expired in June 2007. The Council has recently been granted a short term consent to continue to discharge treated wastewater into Red House Bay at Takapuneke near Green Point. This short term consent (five years) has been sought to allow the Council time to develop an integrated water strategy, based on the best options for providing water supply and wastewater services in a holistic, sustainable and affordable manner that has community support.
A condition of this new short term consent stipulates that the Council meets a series of milestones or target dates to ensure clear progress is being made toward a long term solution for the discharge of wastewater. To achieve this progress the Council plans to establish a working party of representatives from the Akaroa and Takamatua communities to consider and recommend more detailed investigations into the long term options.
The agreed timeline proposes the working party recommend a shortlist of long term options for in-depth analysis in June 2008, with this analysis to be completed by February 2009. Detailed design of the preferred option is to be completed by August 2010 and a new consent application lodged by March 2011. It is proposed tenders be let within nine months of the new consent being granted.
Longer-term wastewater options
The feasible longer term options include discharge of an improved standard of wastewater to the harbour; land application by irrigating to a closed area such as a forestry block or a private property; or reuse by the community for non-potable purposes such as toilet flushing. Combinations of some of these options are also feasible. A long outfall under the harbour to past the heads may also be technically feasible, although the costs have not yet been investigated.
What happens next
The Council proposes to hold two “open day / drop-in sessions”. These information sharing sessions will be held on Thursday June 26 from 4.00 pm to 7.00 pm at the Akaroa Sports Complex in Akaroa, and on Monday June 30 from 4.00 pm to 7.00pm at the Our City Library Room (corner Worcester and Oxford ) in Christchurch. Council staff will provide residents and interested parties with more details on the background work undertaken to date and further information on possible options for wastewater disposal, in particular, and water supply.
Working party
The Council would like to establish a working party of approximately 10 people, including representatives of relevant stakeholder groups. Nominations for this working party can be made to Simon Collin on 941 8380, or at the drop-in sessions. This working party will provide community perspectives to help guide development of the whole water strategy, with initial emphasis on the long term wastewater options. The first task will be to define a minimum of two Akaroa wastewater options for further detailed analysis and costing.
Stakeholder groups the Council would like to see represented on the working party include the Akaroa Harbour Issues Working Party, Akaroa Harbour business interests, Friends of Banks Peninsula, Akaroa Wairewa Community Board and residents groups.
Questions and answers
Q: What is wastewater?
A: Wastewater (sewage) is all the water that goes down the drains, toilets, sinks, plugholes, showers and baths inside your house and into the sewerage system. Pipes and pumps take this wastewater to a treatment plant.
Q: What is potable water?
A: Potable water (drinking water) is all the treated water supplied to each tap on your property.
Q: What is stormwater?
A: Stormwater is all the rainwater that falls on your property and onto your roof. This stormwater can soak into the ground, flow over the ground, or flow into pipes that take it to streams or into the harbour.
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