Construction at one of the world’s most complex multi-purpose hydro power schemes began over 60 years ago in October 1949. Twenty-five years later work finished at the 3756MW Snowy Mountains hydro power scheme in Australia’s Southern Alps; with construction being completed on time and within budget.
Earning the accolade from the American Society of Civil Engineers as one of the seven civil engineering wonders of the world, the scheme is an impressive feat of engineering. Operated and maintained by Snowy Hydro Limited in the state of New South Wales, it boasts 16 major dams, seven power stations, a pumped storage station, plus 145km of tunnels. Water for the project is diverted from the Murray, Murrumbidgee, Snowy and Tumut rivers.
The Snowy Mountain scheme produces an average of 4500GWh per year, currently providing about 70% of all renewable energy available to Australia’s eastern mainland grid. It also provides irrigation water for the country’s A$3B (US$2.7B) agricultural industry.
Various milestones were achieved during construction of the Snowy Mountains scheme. For example:
• The Snowy design team was one of the first to develop interacting rockbolting to create a structural arch.
• In 1951 the team installed 330kV transmission lines, 198kV more than those used at the time. Since then the 330kV lines have became standard throughout New South Wales.
• In 1960 the Snowy Mountains Authority made the wearing of seat belts compulsory in all of its vehicles. This was a decade before the rest of Australia and had a positive impact on the safety of workers in the mountainous construction sites.
• Tumut 3 was the first pumped storage station in the country.
• Snowy Mountains Authority was considered to be at the cutting edge of technology through its use of computer-based techniques. This played a key role in the hydro project’s completion within budget and on time. In 1960 Snowcom was designed and built by the University of Sydney for engineering and design calculations used on the project, and is claimed to be one of the first computers in the world.
Terry Charlton, CEO and managing director of Snowy Hydro said that the company acts as a steward for this engineering achievement. And even with all the modern technology available today he is quite sure that construction of the project would not have been done very differently. However he spoke about the company’s current challenge, which is the need to keep the Snowy scheme relevant and its history alive for future generations.
‘We are spending more on maintenance and upgrade of the snowy scheme assets than those before us,’ he said. ‘We are training and developing our people, and our culture, in ways not previously attempted. We are expanding our electricity generation capability and our business reach considerably beyond that which could have been envisaged so many years ago.’
One direction that the Snowy Hydro has taken has been into small hydro. The company has been taking advantage of small hydro opportunities that exist in the current 3756MW scheme. As part of project works undertaken at the Jindabyne dam to allow for increased environmental flows in the Snowy river, a 1.1MW hydro station was constructed. In addition 6x120kW cooling water micro hydro generators have also been installed at Tumut 3.
The most recent development has been the Jounama small hydro project. Scheduled for completion in 2010, the 14MW scheme will be attached to the existing river diversion conduit at Jounama dam, utilising flows released from Blowering reservoir.
Throughout 2009 work progressed on Snowy Hydro’s seven-year A$300M (US$271M) refurbishment project. New control and protection systems and new turbine runners have been installed, while the mechanical and electrical components have been overhauled at Murray 2 power station (unit 14), plus units1-2 at Tumut 3. Work on the fourth unit is currently underway. Replacement of the control and protection system at Blowering power station was also completed.
The scheduled work for 2010 includes:
• Guthega – refurbishment, upgrade and replacement of the control system.
• Jindabyne – replacement of the control and protection system.
• Tumut 1 – replacement of the main transformer and HV cable.
• Tumut 3 (unit 5) – refurbishment.
In helping to fulfil its role as steward of the project, Snowy Hydro has been undertaking research into winter cloud seeding to increase snow precipitation in the Snowy mountains. Since 1962 there has been a decline in snow within the region, in addition to the extended period of drought that the southeastern part of the country has been experiencing. The Snowy precipitation enhancement research project (SPERP) began in 2004 and the government of New South Wales has given the go ahead for it to continue until 2014.
SPERP will enable Snowy hydro to assess the technical, economic and environmental merits of increasing snowfall over 2250km2 of the Snowy Mountains, which covers a major part of the hydro scheme’s catchment areas.
The importance of the above research can be highlighted by recent data that Snowy Hydro has released about average inflows into the scheme. In November 2009 Snowy storage experienced below average inflows. As a result, water storage levels in Lake Jindabyne and Lake Eucumbene stabilised following the spring runoff and average spring inflows. However since May 2009, inflows have been below average. Lake levels are higher than the same period in 2008 but Snowy storages are still at low levels.
With the historical dry season approaching, it is expected that water levels will drop over the summer and into autumn as the normal seasonal cycle of electricity market and water licence commitments increase. In particular, Lake Jindabyne is expected to drop due to possible electricity market and water requirements.
Achieving the balance that the Snowy scheme has traditionally achieved between the sometimes competing water demands for farms, townships, electricity, the environment and recreational users is described as being extremely difficult, particularly under drought conditions.
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