Cromwell
The Cromwell treatment plant supplies water to Bannockburn, Cromwell, Lowburn, Ripponvale and the southern part of Pisa Moorings (shaded green on the map attached). The treatment consists of chlorination. This provides treatment for bacteria, but not protozoa.
The source water for Cromwell is drawn through bores from the Cromwell Terrace Aquifer. The bores are on the Clutha Mata-au arm of the lake, upstream of the Kawarau River confluence. As the bores are less than 30m deep they are not given secure aquifer status and require treatment for protozoa. The aquifer water has more consistent quality than a surface water source.
Investigation has been underway for a new water treatment plant for Cromwell for the past three years. This has included 24 tests for protozoa over a 15-month period which showed no positives for protozoa.
Further investigation work is being undertaken because additional bores are required to meet the high growth needs for Cromwell. This work will be completed in November and will provide sufficient information to enable the borefield and treatment design to be finalised. The borefield and treatment plant upgrades are expected to be tendered in April 2024, with the construction contract commencing in July.
The new pipeline between the borefield and the reservoir is currently being tendered and will be awarded in October. This will take 10 months to construct, with construction due to be complete in August.