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Lake Waipu Improvement and Rātana Pā Wastewater Treatment Project

Treated wastewater from Rātana Pā is currently being discharged from the treatment plant into an unnamed waterway that leads to Lake Waipu​. Lake Waipu has very high trophic levels, which shows that the lake and its fish and plants are in poor condition.

To improve the health and quality of Lake Waipu, Rangitīkei District Council is working with Horizons Regional Council and the Ministry for the Environment to construct a new pipeline that will remove treated wastewater from Lake Waipu and discharge it to a piece of land near Whangaehu beach area. Once the treated wastewater is removed, Horizons Regional Council is looking into a restoration plan for Lake Waipu, including tree planting and ongoing quality monitoring.

Part of the project is also to look into minor upgrades to the current wastewater treatment plant in Rātana Pā. RDC is working with specialists to design the irrigation system for the land. There is value within treated wastewater which can be used to provide important nutrients to plants even during the dryer times of the year.

This project is being funded by Rangitīkei District Council with some external funding from the Ministry for the Environment.

Rātana Pā Wastewater Project Update

December 2023

Together with our consultants, we are continuing to finalise the response to Horizons’ Section 92 letter which is expected to be returned to Horizons Regional Council by the end of 2023. Delays were encountered by unexpected challenges during the pond sizing and finding the most suitable location.

The discussions with affected landowners around the ideal pathway for the pipeline to the irrigation site is also ongoing. Details around the pump station, pond, pipeline and irrigation design are yet to be finalised. Once the resource consent has been approved and all conditions are known, we will start the procurement of the various components of the civil construction. Where possible we may purchase some products to secure best pricing.

The original cost estimate and LTP budget was $2,425,000 which included the funding through Ministry for the Environment.

Throughout the planning/design phase we have flagged in our updates during the Council meetings that this budget will not be sufficient for the requirements of this project. This budget was set in 2019 and may have been more accurate at the time. However, since COVID-19, cost for construction have increased significantly as well as land value. Requirements for resource consent for land irrigation have become even more complex due to regulation changes and a very wet year of monitoring water tables. Further the length of the pipeline is significantly longer than hoped for, which also is adding to the cost.

The estimates of a standard procurement process for the work were estimated to be around $11 million

The Project Management Office has been looking into options to reduce costs as much as possible, these include:

  • Direct purchasing and storing bulk materials such as pipes, pumps, and storage dam liner to avoid contractors cost margins,
  • Direct procurement of experts, enabling contractors to co-design specific elements to reduce risk transfer from designer to contractor that results in higher unit rate prices,
  • reducing delays between tendering and construction where the holding costs for plant and resources are recovered by the contractor in their unit rates.

In the September 2023 Council meeting the budget for this project has been increased to a total project budget of $6,358,184

21 February 2023

A Resource Consent application was lodged with Horizons Regional Council at the beginning of December 2022. Following this, we received a S92 letter from Horizons Regional Council requesting further technical analysis of the proposal including soil sampling and analysis. The resource consent application has now been lodged with the Rangitīkei District Council.

    30 November 2022

    The subdivision for the purchased land has been finalised in November 2022 and the resource consent application will be lodged with Horizons Regional Council in the first week of December. Once the consent has been approved and consent conditions are known we will be able to finalise the irrigation design and begin the construction phase of the project.