Participate Palmy

How did we get here?

The 2020 feedback and what we’ve done since.

In June-July 2020 we asked for feedback about six potential discharging environments.

More than 1,100 people had their say on the options and environments, with both a full river and full land discharge being the joint most popular choice.

When considering people’s top two choices they also preferred a combination or hybrid of river and land discharges.

During that feedback period, the information provided was still at an early conceptual stage.

Subsequently we ruled out discharging to groundwater as an option, as it wasn’t well liked by our community – both the land areas and the treatment levels required were significant.

We’ve done a lot since then

The information that informed the 2020 feedback period came from our work up to the end of 2019, so we could get your feedback in March. That feedback period was delayed to June-July due to the nationwide Covid-19 lockdown.

Council’s experts have now moved from a conceptual level to a more detailed understanding of each option. This work included investigations to explore proposed treatment levels and applying these to each of the options to determine preliminary effects of any discharge on water quality and land-use, at desktop level.

The nature of the wetland and/or land passage components has been developed, as well as a desktop analysis of the coastal environment and where best an ocean outfall pipe could be located. Land application elements were explored at desktop level to determine how we could meet One Plan targets for nitrogen application and leaching rates, leading to a refinement of the total land areas required. We have also been testing wastewater arriving at and leaving the current plant to understand specific contaminants (such as emerging organic contaminants) and how effectively they are removed.

To understand how we might meet future requirements, we have used advanced modelling tools to determine the potential effects of treatment levels and volumes of wastewater on periphyton (plant) growth in the river. The outcomes of the modelling confirm there are limited options we can consider that will meet these targets.

This new information means we’ve been able to come back to you with a reduced shortlist of three discharge options.

We’ve stepped up our iwi engagement

During the initial stages of this project when we were still considering all potential options for treating and discharging wastewater, our city mana whenua Rangitāne were involved. While we had some initial conversations with neighbouring iwi, following confirmation of a shortlist of options, and a better understanding of the receiving environments, we are now actively engaging with iwi with interests in the potentially affected receiving environments.

We’ve worked with stakeholders to get the reduced shortlist

As part of the option selection process, we have completed a Multi-Criteria Analysis (MCA). The MCA decision tool process is often used in large-scale and complex infrastructure projects in New Zealand to assess options from a range of criteria, and has been tested in the Environment Court. This process provides a systematic way of comparing options using a range of qualitative and quantitative measures. It enables key partners and stakeholders, who are provided with a range of assessments considering technical, social, cultural and affordability issues for each of the options.

The group were able to rank options across a wide range of criteria – and that’s how we’ve ended up with the shortlist that we’re consulting on.

These are the values we considered

We’ll be asking you to rank these values on the feedback form.

Public health

Degree of public exposure to health risks in treated wastewater (including through land application or re-use options.


Degree to which the option is resilient to natural hazards and climate change and offers operational resilience.

Māori cultural values

Potential adverse effects on the mauri of natural resources, on kai moana, and on the relationship of Māori, their cultures and traditions, with ancestral lands, water, sites, waahi tapu and other taonga.

Growth and economic development

Will the option support the population and economic growth the Council forecasts for Palmerston North?

Financial implications

Comparative capital, operational, whole of life costs of the option, assessment of this criterion includes consideration of land acquisition costs, capital gains and product net revenue.

Social and community considerations

Significance of potential social effects based on the gravity, distributive equity, the need for land acquisition and degree of permanence of land use change, and public support for the option.

Natural environment

Potential adverse environmental effects on the receiving environment (including Manawatū River), particularly in relation to water quality (including the matters listed in s107 (1)(c) to (g)), soils, aquatic ecology and terrestrial ecology.

Technology and infrastructure

Degree to which the option:

  • uses reliable and proven technology
  • can be staged
  • is able to be constructed
  • can be constructed within the appropriate timeframe
  • allows resource recovery/ beneficial re-use.