Mikany Dam upgrade

Update March 2019

Background

Mikany Dam is located six kilometers south-east of Smithton in the state’s north west. It is referred to by local residents as Lake Mikany.

The dam was originally built in 1972 and has two main embankments, as well as a smaller embankment which provides access to an island in the centre of the lake. The dam is gravity-fed from the Deep Creek and Muckeye Creek catchment, and is the primary source of potable water for Smithton, Stanley and Irishtown. Water is supplied to these towns via Deep Creek to an offtake downstream, where it is pumped to a treatment plant at Smithton prior to distribution. The reservoir is also used for boating and is a popular fishing spot and picnic area. The community places a high value on the dam in addition to its function of water storage.

Project description

During 2014 TasWater undertook a safety review for Mikany dam, which showed that the dam design is not compliant with modern design standards with respect to piping (internal erosion), embankment stability and flood capacity. The dam therefore requires upgrade, given it currently does not comply with the Water Management Act and associated Australian National Committee on Large Dams (ANCOLD) guidelines. The dam exceeds the ANCOLD-defined limit of tolerability for societal risk, given the probability of failure and the likelihood of fatality should this occur. As a result, a substantial investment of around 7.3 million dollars is required to reduce the risk the dam poses, while also providing a sustainable water supply for customers.

The major features of this upgrade include:

  • Increasing the strength of both embankments by constructing filter and rock-fill berms
  • Improving the spillway in order to bring the dam into compliance with Australian National Committee on Large Dams (ANCOLD) safety standards
  • A small increase in the height of the dam wall to provide protection in the event of a significant flood

The result of the upgrade will be a dam which meets modern standards, is safe, improves water security, and can provide flood protection for much larger floods.

Timelines for the project

Our intention is to begin the upgrade in April 2019, with the project to be completed by April 2020.

Community impact of works

While there will be disruptions to community access during construction, we will endeavour to keep as much of the dam open to the public as possible during the construction phase. We ask for people's patience during this period.

There will also be a large number of truck movements in and out of the site (along the Bass Highway between Smithton and Stanley, and Reservoir Road), in order to move materials needed for construction. There will also be some noise at the site during construction.

For more information

If you have any questions or would like to know more about this project, please contact TasWater's Community Engagement Officer, Ivan Zwart, on 136992 or email enquiries@taswater.com.au

Update March 2019

Background

Mikany Dam is located six kilometers south-east of Smithton in the state’s north west. It is referred to by local residents as Lake Mikany.

The dam was originally built in 1972 and has two main embankments, as well as a smaller embankment which provides access to an island in the centre of the lake. The dam is gravity-fed from the Deep Creek and Muckeye Creek catchment, and is the primary source of potable water for Smithton, Stanley and Irishtown. Water is supplied to these towns via Deep Creek to an offtake downstream, where it is pumped to a treatment plant at Smithton prior to distribution. The reservoir is also used for boating and is a popular fishing spot and picnic area. The community places a high value on the dam in addition to its function of water storage.

Project description

During 2014 TasWater undertook a safety review for Mikany dam, which showed that the dam design is not compliant with modern design standards with respect to piping (internal erosion), embankment stability and flood capacity. The dam therefore requires upgrade, given it currently does not comply with the Water Management Act and associated Australian National Committee on Large Dams (ANCOLD) guidelines. The dam exceeds the ANCOLD-defined limit of tolerability for societal risk, given the probability of failure and the likelihood of fatality should this occur. As a result, a substantial investment of around 7.3 million dollars is required to reduce the risk the dam poses, while also providing a sustainable water supply for customers.

The major features of this upgrade include:

  • Increasing the strength of both embankments by constructing filter and rock-fill berms
  • Improving the spillway in order to bring the dam into compliance with Australian National Committee on Large Dams (ANCOLD) safety standards
  • A small increase in the height of the dam wall to provide protection in the event of a significant flood

The result of the upgrade will be a dam which meets modern standards, is safe, improves water security, and can provide flood protection for much larger floods.

Timelines for the project

Our intention is to begin the upgrade in April 2019, with the project to be completed by April 2020.

Community impact of works

While there will be disruptions to community access during construction, we will endeavour to keep as much of the dam open to the public as possible during the construction phase. We ask for people's patience during this period.

There will also be a large number of truck movements in and out of the site (along the Bass Highway between Smithton and Stanley, and Reservoir Road), in order to move materials needed for construction. There will also be some noise at the site during construction.

For more information

If you have any questions or would like to know more about this project, please contact TasWater's Community Engagement Officer, Ivan Zwart, on 136992 or email enquiries@taswater.com.au