Sewage plant 'really bad', but fix still 10 years off

The plant in Legana - Northern Tasmania's fastest-growing suburb - has been increasingly operating above its licenced inflow capacity since about 2005.

Recent data shows the plant is now receiving about 190 per cent of its capacity, meaning effluent cannot be properly treated before it is discharged into the Tamar River and a reuse dam on nearby farmland.

West Tamar residents Jamie Walker and Peter Kearney, an engineer of 40 years and a former West Tamar councillor respectively, say the issue has reached a critical stage.

"The concern is that no-one wants to talk about this," Mr Kearney said.

"The problem is - and it comes out of TasWater's own documents - that in round terms it's two times over its capacity," Mr Kearney said.

"It means that what goes into the river or onto the pasture is stuff that is, in effect, half-treated.

"How much degraded effluent is going to be sprayed on Lovely Banks within 400 metres of the new primary school?"

TasWater's 2022-23 report on the Legana plant noted it was "heavily overloaded due to significant growth in the catchment".

However, Mr Walker is concerned that reality is not being reflected in the organisation's priorities.

While Legana is ranked 38 of 79 on TasWater's priority list, several other plants that are operating between 80 per cent and 100 per cent capacity have been deemed more urgent.

This includes four plants in the Lower Huon that are considered top-20 priorities.

TasWater did not respond to questions about the relative urgency of Legana, however, general manager of project delivery Tony Willmott said the plant had some upgrades on the horizon.

"In the 2022-23 financial year, 65 per cent of Legana discharge was beneficially reused and later this year we are installing additional aeration to improve treatment performance," he said.

TasWater plans to begin work to transfer Legana's flows to the Ti Tree Bend treatment plant in 2030.

Mr Walker said it was crucial the project begins much sooner given the environmental approvals needed to run pipeline through Tamar Wetlands.

He estimated the building process would take four years from start to finish.

"This has to be the highest priority right now, to fix that problem, because it's really bad," Mr Walker said.

Mr Kearney said the fix was particularly urgent given Legana's booming population and infrastructure growth.

The town has consistently grown by about 120 people every year, and is set to welcome several major development projects in coming years, including the new primary school.

"This is what gets in my craw - [people think] 'it's Legana, we don't have to worry about it and if nobody kicks up about it we'll be able to go on ignoring it'," Mr Kearney said.

"There's only one problem with that - we'll get to a point where somebody will step in, even the [Environment Protection Authority].

"They might actually show some leadership and say 'you're not going to tip any more sewage into your pipelines, so those houses cannot be approved'.

"But as long as the EPA says 'we don't care' ... they'll just go on building more houses and putting it into their pipelines."

The EPA confirmed it planned to complete an audit at the Legana plant next month.

"Assessing compliance with effluent quality limits will form part of this audit process," an EPA spokesperson said.