A new underwater pipeline is set to transport recycled water across Hobart’s Derwent River for agricultural irrigation, firefighting and other community use.
Finishing touches are this week being put on the new $1.1 million seven-kilometre water pipeline, which will pump Class A recycled water from Blackman’s Bay to South Arm.
It is part of the larger $18 million South Arm Irrigation Scheme and will provide treated water to end users on the peninsula, including farmers and the Arm End Golf Course.
South Arm Irrigation Scheme CEO Mary Massina said the installation of the pipeline is a “historic occasion” for the community.
“South Arm is one of the driest areas in Tasmania with limited agricultural capacity, as it is in a rain shadow from kunanyi/Mount Wellington and without access to natural fresh-water sources,” Massina told Pulse.
The pipeline will take one-third of the wastewater from TasWater’s Blackmans Bay facility and, instead of discharging it into the river, will further treat and deliver up to 900 megalitres of water annually.
According to the scheme’s COO Michael Kerschbaum, a 2021 review found that the project has the potential to increase the South Arm area’s agricultural capacity by nine times, from around 40 hectares to 350 hectares.
“Based on the climate and soils, the most suitable options for new irrigated agricultural crops include high value crops such as cherries, viticulture and olives,” Kerschbaum said.
The pipeline is being built using high density polyethylene (HPDE) at a diameter of 250mm, layed at a maximum depth of 26 metres.
It is being installed using a “float and sink” method, with 500-metre segments floated into position from the Margate Marina, bolted together and sunk over a three-week period.
Water is expected to start flowing through the pipeline in the first half of 2025.
