Regular project updates
Council will be publishing a monthly update In the Pipeline to keep the community informed about the Lake Dunstan Water Supply and Clyde Wastewater pipelines construction project. Those interested in the project's progress can sign up to In the Pipeline below.
In the Pipeline will also be available in print at key locations in Alexandra and Clyde.
Contracts Awarded for Lake Dunstan water supply & Clyde wastewater pipelines
Media Release: 16 May 2019
Two significant infrastructure projects that will bring long-term benefits to Clyde and Alexandra are set to start in the next few weeks.
The contracts to construct two major pipelines – one that will deliver a new water supply from Lake Dunstan to Clyde and Alexandra — and another that will transport Clyde's wastewater to the Alexandra Wastewater Treatment Plant — have been awarded this week by the Central Otago District Council.
"The construction of these pipelines represents the start of two massive 'generational' projects for Central Otago that will bring long-term environmental and well-being benefits for Clyde and Alexandra communities," said Central Otago District Council Three Waters Infrastructure Committee chair Malcolm Topliss.
"The Lake Dunstan Water Supply project and the Clyde Wastewater project represent much-needed and significant investment to meet environmental expectations to improve the quality of Clyde's urban water discharges, and for drinking water in Clyde and Alexandra to comply with New Zealand Drinking Water Standards," he said.
Fulton Hogan has been awarded the contracts to construct the two pipelines as approved by Central Otago District councillors at their meeting yesterday (15 May 2019).
"Getting on with these projects means Central Otago will maintain its reputation for clean lakes and rivers. This supports community health and wellbeing, and recreational opportunities," said Mr Topliss.
"In consultation on the 10-Year Plan 2018-2028, the community expressed its support for these major projects and recognised the importance of 'doing them once and doing them right'," Mr Topliss said.
Cost and disruption to the community is reduced by constructing both the wastewater and water supply pipelines at the same time. A huge amount of planning and assessment have gone into getting the projects to the construction start line.
Construction of the underground pipelines is expected to start this month and be completed around the middle of next year. The pipelines will predominantly run along the Otago Central Rail Trail corridor and for short lengths along the edge of State Highway 8.
The estimated cost of Stage 1 of the Clyde Wastewater Project is $13.6 million, $1.9 million more than that presented in the 2018-2028 10-Year Plan. This is due to re-evaluated costs for the rising main and pump station, and reticulation. The overspend will not impact on rates as councillors approved the additional monies coming from the existing Wastewater cost centre.
Tenders for the design of the wastewater reticulation system in Clyde will be called for in the next few months. Construction work on the reticulation phase is anticipated to start in autumn 2020.
The cost of the pipeline and bore work component of the Lake Dunstan Water Supply project is $9 million. More work is needed to determine the final filtration system for treatment so overall project costs are not yet known.
Council has been investigating water supply upgrade options for Alexandra to address customer dissatisfaction with the taste, odour, and hardness of the current supply for a number of years. After investigating a range of possible options, Council determined that Lake Dunstan would provide the best water source.
All residential and commercial properties in Clyde are currently on privately-owned septic tanks and disposal fields. While these are permitted now, commercial septic tank systems may require a resource consent in the future.
People interested in the projects can keep in touch with progress by visiting the Council website, where they will soon be able to subscribe to an e-update. Information will also be available in print.
The Council will be providing information to Clyde residents and businesses before the Stage 1 reticulation phase gets underway around autumn 2020.
Alexandra water pipeline expected to go ahead despite algae discovery
Media Release: 9 May 2019
A Central Otago District Council report released today is recommending that Council proceed with the planned pipeline from Clyde to Alexandra, but has red flagged a delay in the construction of the project's filtration system.
The review on the current state of the Lake Dunstan Water Supply Project was called for after the recent discovery of Lindavia algae, in Lake Dunstan, the species responsible for making lake snow.
The report will be considered by the Three Waters Infrastructure Committee at its meeting next Wednesday 15 May.
Central Otago District Council Executive Manager - Infrastructure Services Julie Muir says: "Our initial filter trials have certainly proved their worth. Finding out about the potential for lake snow now has given us the opportunity to alter our design brief for this project before significant investment takes place."
The new pipeline is due to be completed by mid-2020. An interim chlorination and UV process will be developed to treat water for potential bacterial and viral contamination, and will be ready for use before the completion of the pipeline.
Council will ensure the revised treatment design will not delay the delivery of a new water supply from Lake Dunstan to Alexandra.
Planning for the second stage (a filtration system to meet New Zealand Drinking Water Standards) has been delayed for at least 12 months until all filter trials are complete.
Council's initial trials using simple cartridges have unfortunately indicated disappointing results. The trial cartridge blocked within hours instead of the expected weeks or months. Upon microscopic examination the presence of Lindavia was confirmed.
The discovery of the Lindavia algae this early in the project will ensure that the final filtration system implemented will be able to treat water containing the algae. The findings from current filter trials will also be used to assist with project planning for the Cromwell Water Upgrade (scheduled for 2021).
Lindavia algae is the species responsible for making lake snow, a glue-like slime that blocks water inlets and water filters. This is the first time the algae has been found in Lake Dunstan. It has been causing issues for some time by blocking domestic filters in Wanaka and has also been found in Lakes Wakatipu and Coleridge as well as several North Island locations.
It is non-toxic and poses no known human health risk.
Central Otago District Council is not yet able to confirm the cost of implementing a new filter system and how this will impact overall project costs until a solution is finalised.
The Central Otago District Council is liaising with Queenstown Lakes District Council to share the costs and trials to identify a solution to the Lindavia challenge, which will impact many water sources across both districts.