Bringing together water supplies for two communities under one scheme to provide economical potable water treatment

Lake Dunstan Water Supply

When the potable water supply for Alexandra and Clyde was not meeting the requirements for bacteriological disinfection under Drinking Water Standards, we were there to help.

Our team, in collaboration with our client Central Otago District Council, led the design of this project, from the development of pilot trials of the different water treatment plant systems, up to the production of the project's full technical requirements and documentation for contractors to design and construct the scheme.

Setting out to find solutions, we suspected the proposed concept design using cartridge filters wasn't suited to the characteristics of the sediment in the lake water. Fine glacial rock flour and lindavia algae are known issues with cartridge filters. We engaged a broad community, including our local and international experts, to review available technologies and determine treatment technologies worthy of running pilot trials. The cartridge filters trialled showed significant clogging, even with disc filter pre-treatment; however, the membrane filtration technology performed well. The trials confirmed that membrane filtration combined with chlorine disinfection was suitable for the water quality we saw in the lake.

Our team worked in partnership with eight other organisations to bring the design to life. When the scheme is implemented, these two communities will enjoy safe, reliable and compliant drinking water sourced from high-quality lake water.