Pioneer Dam wall “critically compromised”
A graphic showing potential dam breach extents, from the Tasmanian Parks and Wildlife Service Pioneer Dam Dam Consequence Category Assessment.
May 14, 2025
Pioneer Dam wall “critically compromised”
By Rachel Williams
Water levels at Pioneer Dam will soon be lowered in a bid to prevent the dam wall breaking and causing major flooding, but an ongoing solution to the issue is still to be decided.
Local residents are worried about the immediate risks and what will be done to warn residents and travellers in the area if an emergency was to occur before works are undertaken.
A geotechnical investigation prepared by Geo-Environmental Solutions, at the request of Tasmania Parks and Wildlife Service, outlines “critical deficiencies” affecting the structural integrity, foundation conditions, and long-term safety of Pioneer Dam.
The dam wall and access to the adjacent Pioneer Lake was shut off by PWS in late December following initial concerns about the integrity of the dam wall, including safety of vehicular access across the top of the wall.
It will remain closed indefinitely.
An assessment report by Max Moller, a Civil Hydraulic Engineer with Flussig, said that in his opinion as a specialist in dam safety, flood risk, and hydraulic infrastructure, “the structural condition of Pioneer Dam is deemed to be critically compromised”.
“The combination of low stability factors, poor embankment material quality, and observed signs of internal failure presents a high likelihood of uncontrolled failure if the dam remains in its current state,” Mr Moller said.
“The most risk averse and responsible course of action is to implement an immediate reservoir drawdown, followed by a staged decommissioning plan, unless a clear operational need justifies comprehensive rehabilitation works.”
A PWS spokesperson said it contracted Flussig Engineers to provide advice on how this work should be undertaken, under qualified engineering supervision.
“It is anticipated the next stage of planning and advice will be completed by early July with works to follow,” the spokesperson said.
“A final decision on the long-term management of Pioneer Dam will be made following the next stage of planning, advice and completion of works to lower the dam level.”
There are limited records on the construction of the dam, which is believed to have been built over Bradshaw’s Creek by the Endurance Tin Mining Company nearly a century ago.
If Parks and Wildlife Services deem its retention is essential, Mr Moller has recommended a comprehensive remediation program be developed and implemented.
“This should include a structural stabilisation via engineered buttressing and embankment reconstruction using suitable fill and compaction standards with the installation of subsurface drainage systems to safely manage seepage and reduce internal hydraulic loading,” he said.
But if it’s deemed redundant, Mr Moller suggests systematic removal of the embankment to eliminate downstream flood risk and reduce long-term liability.
Residents in Pioneer should be regularly updated on the progress, potential risks, and emergency procedures to enhance awareness and preparedness should a breach occur, he said.
Parks and Wildlife is yet to outline a plan for that.
Pioneer Progress Association President Alana Keygan said flood modelling showed that a failure could inundate Racecourse Road and Gladstone Road with floodwaters reaching depths of 2.3–3 metres within 45–60 minutes.
“While no homes or businesses are directly impacted, these roadways are key local thoroughfares and could be cut off, affecting emergency access and isolating communities,” she said.
“One of the biggest concerns is the safety risk if the kids are in the river swimming and the dam wall goes, it will hit fast. There is a real need for risk and flood signage to put up around the place because it is serious.
“What are the emergency plans for the town before something is actually done to reduce the water level?”
Ms Keygan said the findings also had serious implications for the proposed Pioneer Sand Quarry, which is still going through an Environment Protection Authority assessment.
Sanbar’s Nick Palmer said they would examine the report.
“We will continue to work with NRE and Parks and Wildlife as we progress our development application,” Mr Palmer said.
Council General Manager John Marik said senior Tasmanian Parks & Wildlife members and Council Officers had recently discussed convening the Pioneer Lake Advocacy Group “as soon as possible to go through report so that key stakeholders understand the contents and implications of the report”.