What’s Council doing to ensure a resilient drinking water solution?

Published on December 02, 2022

Our community has been asking us what we’re doing to ensure a resilient drinking water solution is in place for Levin and Ōhau. While Council has put significant effort into investigating the options available and has set aside budget within the Long Term Plan (LTP) for the work, we still have a long road ahead before concept moves to construction. 

We want to do what's best for the river and our community and we want you to understand the context and challenges to help us find a solution. 

Background

The Levin and Ōhau drinking water supply is currently sourced directly from the Ōhau River at an intake site near the existing Water Treatment Plant (WTP) on Gladstone Road, Levin.

Post-treatment storage of approximately 12,000m³ is provided at the WTP site. This equates to less than 24 hours of supply (less than one day of current peak demand). The post-treatment storage does not provide sufficient storage to meet extended periods of drought or high turbidity (muddiness) in the river. 

Options to increase this are being considered in the short term and will be considered as part of the LTP Amendment.

So what is Council proposing? 

The Water Supply Reservoir project seeks to construct a large scale off-river raw water reservoir to improve the resilience (during heavy rain events and dry weather periods) and reliability of the Levin and Ōhau drinking water supply scheme and to provide sufficient water to meet the projected growth demands for Levin and Ōhau.

Following concept design and a multi-criteria analysis, a single reservoir was selected as the preferred option primarily due to cost considerations and the fact that the embankment required to separate the site into two reservoirs results in a significant loss of stored volume. The storage volume of a single reservoir is in the order of 700,000m³.

What’s been investigated so far?  

• Council has completed a feasibility assessment, which confirmed the feasibility of constructing the reservoir site on Poads Road, Levin. 
• Council also completed an options assessment, reviewing the available water supply and storage options to ensure the chosen option is the right one. This assessment has been independently peer reviewed.
• Iwi engagement has commenced and will continue through the project delivery, should the project and investment be adopted as part of the LTP Amendment.
• A hydrology assessment is in progress and will continue with technical assessments to support the consenting and design processes. Work to date has confirmed availability of sufficient water in the supplementary allocation framework to support the projected community demand.
• A feasibility assessment saw three intake options assessed. This work identified the preferred intake as a subsurface infiltration gallery in the Ōhau river adjacent to the reservoir site.
• An ecological assessment has been completed of the reservoir site. This confirmed there were no wetland habitats, sensitive environments or threatened or endangered species within the reservoir site.
• An archaeological assessment is in progress.
• Preliminary design is in progress with the design being developed to sufficient detail to support consenting and costings.
• Consents scoping is in progress, but given the scale and complexity of the project, we’re working through the options available.