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Environment
AGL Energy Limited 90
Managed water
In addition to the consumption of water resources, AGL
also makes important non-consumptive use of water,
including water drawn from the Port Adelaide River to
cool the Torrens Island Power Station, and the water that
is passed through hydro power stations. AGL takes its
responsibilities as short-term steward of water resources
seriously and manages this carefully.
Approach
AGL’s use of water for cooling purposes at Torrens Island Power
Station is regulated by its Environment Protection Authority licence.
The average temperature increase from the cooling water inlet to
the cooling water outlet is required to be less than 10°C. An external
consultant audits and validates compliance with this requirement
on a two-yearly basis. The last audit report was issued in December
2010, and found AGL to be compliant with requirements, and the
next verification audit will be completed in December 2012.
AGL’s hydro power generation assets are located across Victoria
and New South Wales. The different assets/schemes operate under
different water release arrangements as described below:
>>
Mountain Streams Scheme (Royston, Rubicon, Lower
Rubicon and Rubicon Falls power stations) and the Kiewa
Scheme (Bogong, McKay Creek, Clover and West Kiewa
power stations), Victoria
– AGL holds non-consumptive
bulk water entitlements with the Victorian Department of
Sustainability and Environment (DSE) to use all inflows to the
catchment for power generation at its power station assets.
The entitlement sets minimum and maximum water flows and
rates of change of releases, although AGL has discretion within
these boundaries as to how and when water is released within
the catchments.
>>
Dartmouth and Eildon, Victoria
– AGL holds water agreements
with Goulburn Murray Water (GMW) to generate electricity
from all irrigation releases from these storage dams which are
operated by GMW. AGL owns regulating pondage downstream
of these power stations. Under the water agreements, GMW
specifies what flows it wants in the river system downstream of
AGL’s pondage and so using its pondages, AGL has some flexibility
in how this is achieved. GMW must be notified of any water that
AGL releases so they can allocate the water appropriately to
users downstream.
>>
Cairn Curran and Yarrawonga, Victoria
– AGL holds
water agreements with GMW to generate electricity from all
irrigation releases from these storage dams, which are operated
by GMW. The release of water is dictated by the needs of
irrigators, although AGL has the right to produce power from
any irrigation releases.
>>
Pindari, Copeton, Burrendong and Glenbawn power
stations, New South Wales
– AGL operates these power
stations under a water agreement with New South Wales State
Water that entitles AGL to generate electricity from all irrigation
releases of water from the storages. The release of water is
dictated by the needs of irrigators, although AGL has the right
to produce power from any irrigation releases.
Where AGL has discretion for releases of water (i.e. where water
release is not dictated by irrigation needs), potential environmental
impacts are managed by controlling river discharges to within the
agreed rates of rise and fall and minimum and maximum flow rates
as specified by the relevant authority or agency.
An important annual activity undertaken in the Mountain Streams
and Kiewa schemes is desilting of some of the storages and dams
to maintain capacity and, in turn, the operating flexibility within
the schemes. An environmental working group, (comprising
AGL, the Environment Protection Authority Victoria, Victorian
Department of Sustainability and Environment (DSE), Parks Victoria,
Victorian Department of Primary Industries, local catchment
authorities and the Freshwater Ecology section of the Arthur Rylah
Institute for Environmental Research), meets annually to review
processes, monitoring data and the annual works program.
To minimise the environmental impact of the desilting operations,
the activity is conducted during higher flow winter months. Silt
is removed by direct flushing into the river system, and also by
excavation if required. Environmental parameters agreed by the
desilting working group are monitored at a variety of downstream
locations at a frequency of 15 minutes to one hour depending on
location. This process has been undertaken for more than 10 years
and annual studies indicate that there have been no detectable
impacts on the ecology of the river system, as indicated by long-
term monitoring of macro-invertebrates and blackfish undertaken
by the Freshwater Ecology section of the Arthur Rylah Institute for
Environmental Research at DSE for AGL.
Performance
During FY2012, AGL made non-consumptive use of approximately
584 GL of water drawn from the Port Adelaide River to cool the
Torrens Island Power Station, a 12% decrease compared to FY2011.
Over the same period, the sent out generation from the Torrens
Island Power Station increased by 3%.
More than 5300 GL of water passed through hydro power stations
during FY2012, compared to 4000 GL in FY2011. Following a
prolonged period of low inflows and storage volumes, drought-
breaking rainfall in 2011 increased inflows to the catchments where
our hydro assets are located. In FY2012, many of the regulated dams
at AGL’s hydro power stations were filled to capacity, and inflows
into the Kiewa and Rubicon hydro schemes were around long-term
average inflow levels.
Desilting operations occurred as planned for the Kiewa and
Rubicon hydro schemes for FY2012. AGL is intending to install
automatic monitoring systems at selected locations on both the
Kiewa and Rubicon Rivers to monitor the impacts of desilting by
recording parameters including turbidity, pH and temperature
at 15 minute intervals. A trial system has been installed on the
Kiewa River at Tawonga Bridge to measure impacts of the 2012
Kiewa desilting activities. This monitoring will also provide valuable
information on the natural annual range of the variability of the
measured parameters.
Watermanagement