​Work to bypass around Phoenix Dam successful

The work to bypass around the Phoenix Dam has been completed and is ensuring the supply of water will continue for Lawrence.

Clutha District Council (CDC) Deputy CE Jules Witt says “It is reassuring to have the bypass operational and working effectively. The work was successfully completed in early May with the bypass commissioned on 6 May. Aside from a minor washout following some rain in the first week, it had been providing the township with clear water and estimates are that it is running at the spillway at around 9 litres/second.”

Mr Witt said the bypass work had been a top priority for Council following the dam owner Port Blakely’s intention and subsequent formal notification to decommission its dam due to ongoing safety concerns related to the age of the dam.

While there is a boil water notice in place for the Lawrence township this relates to a separate issue due to problems with water treatment at the plant regarding chlorine levels.

Resource consent has been sought to undertake the bypass work and Port Blakely Limited had given consent to do this work on their land.

Mr Witt said Council was acutely aware that it’s water source at Blue Jacket Creek (the Phoenix catchment) would be insufficient to ensure continued supply to Lawrence and alongside the bypass work, further work was being done be able to pipe water from another source at Bungtown Creek.

“Observant locals may have noticed a helicopter at work in the area to lower around 200kg of pipework into the forest owned by Rayonier Matariki Forests.”

This work has been split into two sections, with two contractors responsible for different components of the work. Isaac Construction are working on the section from “the tunnel” (an archaeological feature within the race) and local contractor Bill Fitzgerald will be moving to work on the upper section of the race now that he has completed works on the bypass.

The Bungtown race and siphon were constructed prior to 1900 and Council has sought approval from Heritage NZ before undertaking any improvement works.

“We hope to have the Bungtown Race operational, likely by mid-June weather conditions permitting,” Mr Witt said.

Flood protection work to lower the level of the Phoenix Dam involved a controlled dewatering operation which began in November 2023, a joint operation involving the dam’s landowner Port Blakely Limited, CDC, Otago RC and Emergency Management Otago.

The risk reduction work involved lowering the level of the dam by 3 metres by way of a siphon system and was achieved at the end of January.

The bypass is a temporary solution until the new Greenfield Bore (with water supplied from near the Clutha River) is operational, which will supply the Lawrence township in the future.

This is under construction and involves a new water treatment plant and the amalgamation of pipe networks with four pumping stations and a network of 48.5km of pipework.

Council has lifted the Stage 3 Water restrictions for Lawrence as we are now approaching winter. However, Council asks residents to continue to mindful of their water use and report any leaks.

Phoenix Dam is a historic water supply dam located 3km north-east of and above Lawrence, Otago. The dam was originally constructed in c.1863 for goldmine sluicing.