Pioneer Dam decommissioning

Client: Tasmania Parks and Wildlife Service
Location: Pioneer, north-east Tasmania, Australia
Dates: May to July 2026

Combining dam safety engineering, environmental oversight and responsive construction supervision to reduce a dam safety risk and restore a natural waterway for a historical mining dam

Services

• Dam safety engineering
• Construction inspections and technical advice
• Environmental surveys and monitoring
• Heritage assessment

Background

Pioneer Dam was a 9 m-high embankment dam on Bradshaws Creek near Pioneer in north-east Tasmania. Constructed approximately a century ago, it impounded a reservoir of around 1,200 ML to supply water to the local tin mining industry. The dam was used predominantly  until the mid-1940s, with intermittent mining continuing until 1979, after which it no longer served a mining or water-supply purpose.

Over time, the condition of the dam deteriorated significantly. Engineering and environmental assessments identified safety risks associated with the ageing structure, which was classified as a ‘Significant’ consequence category dam under Australian National Committee on Large Dams (ANCOLD) guidelines. Tasmania Parks and Wildlife Service decided to decommission the dam to remove the water storage and associated safety risk, restore the natural flow of Bradshaws Creek and support the area’s continued recreational and environmental use.

Entura was appointed Project Superintendent and provided the Class 1 engineering supervision required under Tasmania’s dam safety regulations. Shaw Contracting was engaged to undertake the physical construction works.

Solution

Entura brought together dam engineering, construction supervision, environmental management and heritage expertise to support the safe and compliant delivery of the project.

An Aboriginal heritage and historical heritage assessment of the dam site and a flora and fauna study identified no notable heritage and environmental issues associated with the dam decommissioning.

Our team prepared a decommissioning plan, an erosion and sediment control plan, rehabilitation plan and dam safety emergency plan. These supported a carefully staged approach involving controlled reservoir dewatering, selective vegetation clearing, partial excavation of the embankment, management of excavated material and construction of an erosion-protected channel through the former dam wall.

Entura’s engineers and environmental specialists inspected key stages of the works, including site establishment and dewatering, outlet pipe removal, dam stripping, stockpile preparation, embankment excavation, water quality management and practical completion. These inspections verified that the work aligned with the design intent, approved plans and regulatory Direction Notice.

The team also responded to construction conditions revealed during dewatering and embankment excavation. The excavation design was adjusted to avoid unnecessary excavation while still creating a stable channel that would prevent future impoundment. Rockfill over geotextile protected the new channel batters, with large rock installed through the channel and stilling basin to dissipate energy and reduce erosion.

Environmental monitoring continued throughout dewatering, construction and post-construction. Although some localised turbidity occurred, monitoring found that suspended sediment settled rapidly upon reaching Pioneer Lake. Disturbed areas were rehabilitated using topsoil and vegetation slash generated during the works.

Outcome

The decommissioning works were completed in June 2026. Partial removal of the embankment permanently removed the dam’s capacity to store water and restored natural flow through Bradshaws Creek. Entura’s final inspections confirmed that the works had been completed satisfactorily from dam safety and technical perspectives and in accordance with the Direction Notice.

Through integrated engineering, environmental and construction phase services, Entura has helped transform a deteriorating and redundant dam into a safer, more sustainable site, restoring the waterway while supporting the community’s continued enjoyment of Pioneer Lake.

Pioneer Lake reopened to the public on 31 July 2026, ahead of schedule. With 550 rainbow trout stocked in preparation for the reopening, the lake is once again supporting recreational fishing, while PWS and Entura continue monitoring the site’s rehabilitation and revegetation.