In September last year, Council chose to have the highest treatment currently available in New Zealand and made a commitment to continue to reduce wastewater in the city, and to consider it as a resource. The treated wastewater would be discharged the Manawatū River 75% of the time and irrigated on land when the river is at below median levels.
We’ve indicated we will be lodging our consent application with the regulator, Horizons Regional Council on 31 December 2022.
From then, the regional council considers and may choose to notify the consent application as part of its process. Council will continue to do significant work during this process.
River discharge location close to being confirmed
Over the past few months, we’ve been doing further modelling on the river and have identified a potential location for where the highly treated wastewater could be discharged from. Currently we’re modelling what that environmental impact would be, and then we will be able to confirm it. We’re continuing to work closely with iwi on this work.
Land work is progressing
The land component of our consent application is our most challenging element to complete in time for our consent to be accepted. A lot of work is planned for the next three months.
In our last update we said we’d identified a large area west of the city, close to our treatment plant, which potentially had the right soil types for absorbing treated wastewater [see map below]. We contacted landowners within this area in about soil testing in May and have now been able to test three properties. Those tests confirmed that the area had the soil types previously identified in our desk top assessment.
We stated at the time and will reiterate that where we tested does not mean we want to use those properties for the irrigation. People who own property in the area identified in the map will also be receiving this update.
A summary of the soil testing written in August is now also available. The 3 types of soil that were tested for are known as Gley, Recent/Raw, and Pallic.
The report states that the best soils for drainage are those that are recent/raw, and that if that soil type is used, we’d need around 600 to 710ha of land, and 75,000m3 for storage. This is less land than we indicated in September 2021.
Gley soils were the next most effective for drainage, but only 38% as effective as the recent/raw type, meaning they’d require more land.
Pallic soils were deemed to be extremely restrictive and could pose a high risk of significant cost escalation.
The report only details testing on 2 of the properties, as the third property was for sale and the testing was done as part of due diligence. The testing showed that property was not suitable for wastewater discharge.
Please note, Figure 3 has been removed from the report as it identifies individual testing locations on private land. As these were given on a voluntary basis by landowners, we want to protect the locations and their individual test results.
Soils Interpretive Report
We’re looking at applying for a global consent, where we’d get consent for the discharge for a general area, only needing to identify 1 or 2 properties to use as the example for the consent.
This approach would mean we wouldn’t need to procure all 760 hectares needed during the 30+ year consent, in advance of that land being needed. This limits disruption to the farming community. It also means that any potential new Three Waters Agency would be able to determine the best locations based on its needs.
We are in the final stages of confirming some pilot properties, based on size and soil types, and will be contacting those landowners directly before mid-October.
We’ll be asking them what their long-term plans are for their properties and if they have any interest in selling or leasing land to us from 2028, when we will need it.
First look at upgraded treatment plant now available
Council is committed to having the best treated wastewater in New Zealand, and our proposed methods will have our treatment amongst the world’s best, and just one step away from drinking water.
There are 2 significant new steps. The first is introducing the removal of nitrogen, which can at high levels affect plant and freshwater life in our awa (river.) The second is microfiltration, which will enable us to remove particles as small as 0.04 microns, which is smaller than the human eye can see and includes things like bacteria and viruses.
A new video released today shows what our existing treatment plant will look like with these new steps included. Watch it to compare our current processes to our new process.
This concept video only shows our current proposal, but we’ve also committed to improving the plant or processes if technological advances could further improve the quality of our treated wastewater.
As part of our consent application, we’re also looking at adaptive management. This includes:
Establishing a framework for managing any environmental risk and uncertainty.
Having a framework for reducing the amount of wastewater generated by the city.
A plan for reducing the volume of treated wastewater discharged to the river over the life of the consent .
A strategy to establish investigations and actions for the Council to implement over the consent period.
Our project reference group, made up of several stakeholders, technical and iwi representatives is working through this.
We’ve only got a few more steps before lodging our consent
With the clock ticking, the next step for our Nature Calls project is to prepare the consent application, pulling together the five years' worth of technical work and assessments. Our reference group will continue to meet and work on the adaptive management strategy.
Due to the impact of Covid-19 on our timeframes, and needing more time for lodging our consent, this week Council brought forward already budgeted money from next year’s Nature Calls budget into this year’s budget. As it was already budgeted money, this has no additional impact on ratepayers.
While the government is working on the Three Waters Reform, we are legally required to continue with this project as it is a requirement of our consent.
We will provide another update when we lodge our consent. Once it has been accepted by Horizons Regional Council, we will make it publicly available on our website.