Dam Design and Construction

Hydro Tasmania cleared to begin upgrades at Edgar Dam

Hydro Tasmania cleared to begin upgrades at Edgar Dam
(photo courtesy Hydro Tasmania)

The Federal Government has given the green light for Hydro Tasmania to start upgrades at Edgar Dam, in southwestern Tasmania.

The office of Environment Minister Tanya Plibersek confirmed the works will not have significant impact on the Tasmanian Wilderness World Heritage Area (TWWHA) or other matters of national environmental significance provided that the action is undertaken in the particular manner set out in the decision.

The decision follows consideration of the works under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.

The federal Department of Climate Change, the Environment, Energy and Water (DCCEEW) determined the works “not a controlled action – particular manner,” accepting Hydro Tasmania’s specific environmental controls and deeming no further assessment or conditions are necessary.

Edgar Dam is one of three dams edging Lake Pedder. Built in 1972, it is part of the Gordon-Pedder scheme, capturing 40% of the water that supplies Tasmania’s largest hydropower station, 432 MW Gordon Power Station. This station can generate up about 13% of Tasmania’s annual energy needs.

Hydro Tasmania Assets and Infrastructure Executive General Manager Jesse Clark said the decision paves the way for works to commence later this year. “It’s great to get to this point after several years of design, planning, approvals and community consultation,” he said. “We’ll now conduct a tender process for specialist construction services to deliver the works over two summers.”

Environmental controls put forward by Hydro Tasmania include:

  • Restricting truck movements within the TWWHA to daylight hours to minimize impacts to wildlife
  • Washing vehicles thoroughly before entering and exiting the site
  • Importing materials from a commercially accredited quarry
  • Keeping the site footprint and vegetation clearing to a minimum
  • Edgar Dam is adjacent to the Lake Edgar Fault Line, which was thought to be inactive at the time of construction. After extensive investigation, experts determined the fault could not be considered inactive. Upgrade works will include new downstream gravel filters and rock fill to support the existing dam. This will improve seismic resistance of the dam, in the extremely unlikely event of a major earthquake, in line with national guidelines.