Central Otago District Council reviewed a business case on 31 May 2017 for the Lake Dunstan Water Supply Project and agreed on preferred construction and treatment options and the pipeline route.
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. The Lake Dunstan Water Supply project will also ensure the water scheme meets the New Zealand Drinking Water Standards.
In December 2013 Council received a report, which identified a preferred option of:
- extending the bore field at the Clyde water supply source,
- building a single treatment facility at Clyde to service both the Clyde and Alexandra water supplies, and,
- constructing a pipeline between the Clyde treatment site and the Alexandra Northern Reservoir.
In considering the latest (31 May) report Council gave approval to proceed with tendering of a contract for detailed design based on the following parameters:
- A single 450mm diameter trunk main to be constructed between Clyde and the Alexandra Northern Reservoir via State Highway 8 and the rail trail corridor.
- Inclusion of all treatment stages required to meet the New Zealand Drinking Water Standards at the same time as design and construction of the pipeline and bore head works – which could include cartridge filter, ultraviolet and chlorine treatment if water testing identifies the need.
- Additional capacity at the Alexandra Northern Reservoir to be provided for in 2024, and a booster pump in the pipeline in 2040.
Construction of the treatment works will not commence until after the 2018 Long Term Plan is adopted. This will provide the opportunity to revisit the priority and timing of all significant infrastructure projects and enable public consultation on options.
Mayor Tim Cadogan said the decisions were important as the project represented "a big investment in our community and a big investment in the future of the community".
"The message from our community in prior consultations on the upgrade have been 'to do it once and do it right', and in light of recent events in Havelock North we can't muck around when it comes to public water supply management."