Water reservoir proposed
The Horowhenua District Council’s water storage capability for Levin is set to increase greatly with a proposal to build a huge new water supply reservoir.
The council has proposed to build a new reservoir on Poads Rd, which is off Gladstone Rd southeast of Levin.
The Levin and Ō hau drinking water supply is sourced from the Ō hau River at an intake site near the existing water treatment plant on Gladstone Rd.
The water treatment plant has posttreatment storage of about 12,000 square metres, which equates to less than 24 hours of supply or less than one day of 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 Long Term Plan amendment.
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 Ō hau drinking water supply scheme and to provide sufficient water to meet the projected growth
Following concept ¯design and a demands for Levin and Ohau. multi-criteria analysis, a single reservoir was selected as the preferred option primarily due to cost considerations and because 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 about 700,0003.
A council statement said it had put significant effort into investigating the options available and set aside budget in the Long Term Plan for the work, but it still has a long road ahead before concept moves to construction.
Council chief executive Monique
Davidson said the council was hopeful and had done a lot of groundwork to ensure they have considered what’s best for the river and the community.
‘‘There are some key milestones yet to be achieved, which means we can’t get ahead of ourselves. The consenting process is complex and could take several years, given the scale of the work proposed.’’
She said their iwi partners and other groups involved needed to be confident the proposed solution was the right one.
The council needed to give the community the right information and listen to their views before a solution went before elected members ‘‘for adoption and the green light to invest a significant amount of money’’.
‘‘It’s important that our community understands that the challenge we face is not just constrained to water supply or storage.
‘‘There is a shared responsibility to use water sustainably for both council and the infrastructure we maintain and for everyone in our community.’’
The council has completed a feasibility assessment, which confirmed the feasibility of the reservoir site on Poads Rd, Levin, for construction, and an options assessment, reviewing the water supply and storage options.
A hydrology assessment is in progress. Work has confirmed there is sufficient water to support the projected community demand.
A feasibility assessment found the preferred intake as āsubsurface infiltration gallery in the Ohau River adjacent to the reservoir site.
An ecological assessment confirmed there were no wetland habitats, sensitive environments or threatened or endangered species within the reservoir site.
An archaeological assessment and preliminary design is in progress.
Consents scoping is in progress, but given the scale and complexity of the project, the council is working through the options available.