Poatina Buffer Dam

Location	Poatina, Tasmania
Client	Tasmanian Irrigation
Head Contractor	Hazell Bros Group
Type of work	Bulk earthworks, concrete structures, electrical and roading
Overall Project Value	$22 million
Status	Completed October 2025

Hazell Bros was awarded the contract to construct the Poatina Buffer Dam, a key component of the Northern Midlands Irrigation Scheme, which, when completed will provide water surety to farmers across the Northern Midlands area.

The 660ML clay lined turkey nest style embankment dam takes irrigation water from the Poatina Power Station tailrace channel through a newly installed inlet structure and channel for storage prior to distribution to the irrigation scheme through the Poatina Pump Station.

Scope of works included:

Site clearing and topsoil stripping (~17Ha)
Bulk earthworks including embankment construction and clay liner from site won material (~300,000m3)
Upstream rock armour/filter (~85,000T)
Perimeter interception drainage trench (DN315) and associated pits and dewatering pumps
Insitu concrete outlet pit and pipes (5 x DN630 HDPE, concrete encased)
Inlet structure (precast/insitu) including Rubicon flume gates
Demolition and replacement of drop structure (precast/insitu) in existing tailrace during a planned power station outage
Access roads and landscaping
Instrumentation & telemetry

Bulk earthworks were undertaken using a combination of 627 scrapers, articulated dump trucks, dozers and excavators selectively mining material from the onsite borrow in the dam footprint and moving to the corresponding location in the dam embankment or dam floor. Moisture was controlled with water carts in the borrow and compaction completed using an 815 compactor and pad foot rollers.

Rock armour and filters were sourced from Hazell Bros Long Hill and Raeburn quarries with Hazell Bros Transport playing a major role in getting large quantities of materials to site in a safe and timely manner.

Concrete structures were optimized for efficiency, safety and constructability with precast elements used where possible. These elements were supplied from Hazell Bros Precast yard in Ulverstone.

The project was completed in 11 months, allowing sufficient time to commission and test the dam in advance of water being supplied to irrigators in October 2026.

This project is another example of Hazell Bros’ vertically integrated business model, showcasing the seamless collaboration between our Quarry, Plant Hire, Concrete, Precast and Transport divisions, as well as our testing laboratory, QualTech TAS to deliver another major project on time and to the client’s specifications.