Greytown Drinking Water Services Consultation
South Wairarapa District Council (SWDC) is seeking to progress with an upgrade or replacement of the water treatment facilities in Greytown to increase the resilience of the Greytown drinking water supply.
The existing bore and water treatment facilities at Soldiers Memorial Park is the primary supply for Greytown. These assets are in very poor condition and need upgrading or replacement to ensure an ongoing reliable supply of safe and healthy drinking water, and to provide enough water for firefighting.
Currently it is not possible to undertake maintenance of the existing pump or bore without disrupting water supply to Greytown. Without regular maintenance the bore is at an increased risk of failure.
Therefore, Wellington Water have recommended to upgrade or replace the water treatment plant to ensure Greytown continues to receive a reliable supply of safe and healthy drinking water.
The South Wairarapa District Council, in partnership with Wellington Water, is seeking your feedback on the options.
The Proposal
Council is proposing to construct the new bore and water treatment facility in Greytown, either by:
- Installing a new bore somewhere in Soldiers Memorial Park (but outside the existing site of the swimming pool) to provide a backup to the existing bore and a new treatment plant. This proposal would remove the temporary container for the existing plant from the main carpark and replace it with a new containerised plant located away from the parking area returning the carpark to the community.
OR
- Selecting a new site on which to construct two new supply bores (a primary bore and a backup bore to provide duty/standby operation) and a new treatment plant to replace what is currently installed at Soldiers Memorial Park. The two options for the new sites are the Old Borough Council yard on West Street, or to purchase land in the Kuratawhiti Street area.
Council is also proposing to fund the water treatment facilities in Greytown, either by:
- Funding the options through the District Targeted Water Supply Rate. The ongoing cost would be shared by everyone in the district who is connected to (or can be connected to) district water supply.
OR
- Funding the options through the District Targeted Rate PLUS an additional Local Targeted Rate to be paid only by ratepayers connected to (or able to be connected to) the Greytown water supply network. The ongoing cost would be split into two;
– a base amount would be shared by everyone in the district who is connected to (or can be connected to) district water supply.
– an additional amount would be paid by everyone connected to (or can be connected to) the Greytown water supply network specifically.
Timeline
Activity | Date |
Consultation opens | 9 September |
Drop in event at Soldiers Memorial Park | 28 September, 10am – 12pm |
Consultation closes | 9 October |
Hearings | TBC |
Deliberations | TBC |
Tell what you think before 9 October 2024 by:
- Filling out the online feedback form
- Email your feedback to submissions@swdc.govt.nz
- Paper copy – print off this form and;
– Email it to us at submissions@swdc.govt.nz or
– Post to PO Box 6, Martinborough 5741 or
– Drop it in to the Council office or any of the South Wairarapa libraries.
This consultation is a Special Consultative Process (SCP) and will require hearings or deliberations to take place. The feedback given will be provided to the Council as background information to aid decision making in relation to the decision.
Meet with us
If you are a group that would find it beneficial to meet with Council and Wellington Water about this consultation, please contact us via haveyoursay@swdc.govt.nz
Soldiers Memorial Park drop in session: Saturday 28 September, 10am – 12pm at the Playground.
FAQs
How did you identify the two alternative sites for the Greytown treatment plant?
This involved three screening stages. At each stage a possible site had to meet a set of requirements to move to the next stage. We also had information from different sources at each stage, including discussions with knowledgeable locals.
It was a detailed process, but here’s a simple summary:
- Initial long list – we identified a long list of 11 possible options. To make this list the site must have access to the aquifer. We also had input from geographic maps, SWDC information and local knowledge.
- Long listed sites – We long listed 10 sites. To make this list, the must haves include reasonable access to utilities, vehicle (chemical truck deliveries) accessible. We had input from water treatment and civil engineering technical specialists and Wellington Water.
- Two sites short listed – To make this list, the site must have connection to 11kV electrical network, be truck accessible and be near to water and wastewater infrastructure. The site must also have capacity to accommodate key factors like community health and safety risk, flooding and contamination risk and be near critical services. Our input sources included stakeholders and technical engineers.
Having met all requirements for an alternative site, the two shortlisted sites were assessed using a Multi Criteria Analysis (MCA) process. This involved scoring each site against critical criteria (such as consentability, social and cultural impacts, flood risk, soil contamination risk). Through this process cost factors and ranges were also estimated.
Why haven’t other alternatives been explored, such as water supply sources investigated in the past?
Greytown has sourced its drinking water from the Waiohine river since the 1940’s, with a weir being constructed at Bassets Creek. A storage pond allowed water from the river to be treated with chlorine. The Waiohine water treatment plant was constructed in 1999 allowing treated drinking water to be supplied to both Featherston and Greytown.
The increasing demand for drinking water and need to supply sufficient water for firefighting from Greytown’s growing community resulted in an additional bore being drilled at Memorial Park to supplement supply from the Waiohine treatment plant in 2005.
Alternative sources of water for Greytown are very limited. Finding a reliable alternative source not already in use would require exploratory drilling with no guarantee of locating an improved quality or suitable quantity of water to meet Greytown’s needs and will require significant investment and time to implement.
How does the Memorial Park water treatment plant upgrade fit into the wider supply strategy for South Wairarapa?
You can view an interactive StoryMap on the history of the development of South Wairarapa’s water supply and the background behind the existing Memorial Park treatment plant here
Supply of safe and healthy drinking water to the public on behalf of the South Wairarapa District Council (SWDC), and all our client councils, is Wellington Water’s number one service goal.
Upgrade or replacement of the Memorial Park treatment plant to provide a multi-barrier approach and a reliable supply of safe and healthy drinking water for the community is therefore currently Wellington Water’s highest priority project for SWDC.
If the Memorial Park water treatment plant is supplying water that is deemed safe and compliant, what else needs to be done?
The water treatment plant, with a temporary containerised Ultra Violet (UV) system in place, is supplying safe and compliant water.
However, we need to maintain ‘multiple barriers against contamination’. This is one of the six principles of safe drinking water, stated in the Report of the Havelock North Drinking Water Inquiry: Stage 2: ‘Principle 3: Maintain multiple barriers against contamination: Any drinking water system must have, and continuously maintain, robust multiple barriers against contamination appropriate to the level of potential contamination. This is because no single barrier is effective against all sources of contamination and any barrier can fail at any time. Barriers with appropriate capabilities are needed at each of the following levels: source protection; effective treatment; secure distribution; effective monitoring; and effective responses to adverse signals. A “source to tap” approach is required.’
While the UV system in place at the Memorial Park provides a barrier and the treatment plant is monitored closely, there remains a risk that the single barrier against protozoa such as Giardia and Cryptosporidium that is in place might fail.
Why do we need another bore when there’s one there that works already?
The current bore still meets demand but there is no backup and this creates supply risks. The pump and treatment facilities are very old and need replacing. The older they get, the more risk there is of failure. Without backup, we cannot switch off the pump and treatment facilities to allow for repairs, maintenance, or replacement without compromising supply pressure and fire flow availability to areas of Greytown for extended periods -particularly at times of high demand.
It also means we don’t have the ability to commission the planned new treatment facilities ‘offline’, without causing an extended outage to complete the project, with similar impacts to those noted above for a very long period of time.
The proposed new bore will provide much-needed backup or ‘redundancy’ in the network, and combined with the new plant and treatment facilities, ensure a resilient and reliable supply of safe and healthy drinking water to the Greytown community.
An additional benefit is that the proposed work would remove the existing unsightly temporary container for the plant and treatment facilities and replace it with another that is discretely located away from the main car parking area.
Is there a risk that a new bore could damage an existing structure like the swimming pool or a nearby building during construction or when in operation?
Any new water supply bores will be designed near the water treatment plant taking into account the relevant constraints of the site. The new bore location will consider factors such as impacts during construction of the bore (which can include vibration or ground settlement) as well as operational impacts in addition to the bore yield.
These factors will be checked by completing ground investigations. If the site constraints lead to a bore being placed close to an existing structure then additional assessments will be completed to inform the design, and the construction methodology developed to mitigate these impacts and avoid adverse effects. However, in the first instance the designers are trying to avoid such risks by placing the bore in a location relatively away from existing structures.
What would happen to the existing facilities at Memorial Park as part of the proposed upgrades?
The proposed work would remove the existing temporary container in the main carparking area and replace it with a new containerised water treatment plant, discretely located away from main parking area to the right side of the pool complex.
Once the treatment plant was up and running the proposal would be to remove the existing containerised treatment systems enabling the car parking to be returned to the community.
Why don’t we shut down the Memorial Park water treatment plant and focus all investment into the Waiohine water treatment plant?
The Waiohine plant alone is not currently capable of supplying both Featherston and Greytown during high demand periods due to the constraints and hydraulic limitations with the existing supply network.
In more detail, let’s examine how the supply network currently works. Two treatment plants serve Greytown: the Waiohine plant, which also supplies Featherston, and the Memorial Park plant that supplies Greytown only.
During high demand periods, Greytown relies on the Memorial Park plant operating to provide sufficient water supply pressure. When demand drops below a certain level, such as at night, the Memorial Park plant cannot operate due to its minimum flowrate constraints and it shuts down. This in turn causes the network pressure in Greytown to drop below the set point of a control valve in Humphries St and it opens to supply Greytown from the Waiohine treatment plant.
When demand for water increases again, such as in the morning, the valve closes and the Memorial Park bore restarts to meet the higher demand in Greytown. Ultimately, without Memorial Park operating during the day, network pressures would drop below that required for firefighting and supply of safe drinking water to areas on the edge of Greytown’s water supply network.
Hydraulic modelling shows that around 8km of watermains would need to be replaced with a high-level cost estimate of the order of $18million to resolve these issues, together with further work to improve the hydraulic connectivity between the Waiohine water treatment plant and the Greytown reservoir that is located close to the treatment plant.
Even after completing all this work, operational resilience would be reduced as there would be no alternative supply to Greytown in the event of disruption of the supply from the Waiohine water treatment plant. The Memorial Park bore and treatment plant, or alternatively a new bore supply and treatment plant elsewhere in Greytown will provide the necessary hydraulic pressure to resolve these issues, and provide increased operational resilience compared to supply from the Waiohine water treatment plant only.
Is the Waiohine water treatment plant operating at full efficiency? That is, are the bores producing as much water as possible?
Yes. A fourth bore was installed at the Waiohine plant, and an 8 million litre treated water storage reservoir (bladder) has recently been commissioned that both allow the treatment plant to operate as efficiently as possible.
Why not make the Waiohine treatment plant the primary supply for Greytown, and install the containerised plant in Featherston to supply Featherston residents? This would remove the need for the Tauwharenikau pipeline.
As noted in the earlier question, the Waiohine treatment plant operating alone is not sufficient to supply Greytown during high demand periods due to network hydraulic constraints. It is also important to build and maintain network operational resilience by having multiple sources of drinking water available when required due to any unforeseen circumstances that could occur at either treatment plant or with the supply pipelines between the treatment plants and Greytown.
In 2012 Groundwater Investigations adjacent on the Featherston side of the Tauherenikau River were completed and concluded that ‘the groundwater potential in this area is poor’. In addition to this, the Abbots Creek, Boar Bush and Taits Creek surface water supplies are no longer suitable for Featherston’s needs. To see more details view our South Wairarapa District Council water supply story map here.