Dam Safety
Would you build a pumped hydro power station in a populated valley downstream from a dam which already has safety concerns?
French energy giant EDF plans to build a 300MW large-scale pumped hydro power station at a site 50km east of Tamworth, and just 5km downstream of Dungowan Dam. As part of the Dungowan Pumped Hydro Energy Storage (PHES) project, EDF wants to store more than 3 gigalitres of water in a reservoir in the valley.
Local residents have real and valid concerns that EDF's reservoir will contribute to increased loss of life and property in the event of the catastrophic failure of Dungowan Dam. If the dam wall broke, the resulting inundation would be increased if it picked up an extra 3
gigalitres of water from EDF's reservoir. Pumped hydro in the Dungowan Valley makes our lives less safe and increases the risk to our property. This is one of the main reasons we oppose EDF's project.
The bottom line is that building a pumped hydro power station downstream of an existing dam in a populated valley is just too risky. It's bad for Dungowan Creek and it's bad for the ratepayers of the Tamworth region. EDF couldn't have picked a worse spot for pumped hydro. We say "non merci" to pumped hydro in the Dungowan valley!
Risk management and Dungowan Dam
Dungowan Dam was opened in 1957 and can hold up to 6.3 gigalitres of water. It is owned and operated by Tamworth Regional Council, and is a "declared dam" under the supervision of Dam Safety NSW. Its most recent dam safety report was published in March 2023. The most recent risk assessment report for the dam was published ten years earlier (in 2013), and the next risk assessment is due in 2028. In NSW, there are three main measurements of dam safety: consequence category, societal risk rating and individual risk rating. In 2013, Dungowan Dam scored poorly on all three measurements. You can learn more about those measurements here.
The consequence category measures the consequences of catastrophic failure of a dam on a scale of very low, low, significant, High C, High B, High A, and extreme. A dam's category is based on the "potential loss of life" and severity of damage and loss of property that would result as a consequence of a dam break. In 2013, Dungowan Dam was a High A (between 5 and 50 fatalities and damage between $10m and $100m) consequence category dam. After subsequent work undertaken by council, it is expected that the category would now be High C (less than 5 fatalities). That downgrading of risk will be reversed if pumped hydro is built in our valley. It is possible that Dungowan Dam would skyrocket to Extreme because during construction the workforce is expected to be around 500 people living on site - all at risk of death in a catastrophe, and property loss would increase above $100m if the pumped hydro station itself is damaged.
The societal risk rating is based on the probability of dam failure and the expected number of casualties. In 2013, Dungowan Dam scored poorly with a societal risk rating of 8.0E-5. That's almost eight times higher than the nearby Chaffey Dam, which scored 1.08E-5. Again, Tamworth council has spent millions of dollars to increase the height of the dam, purchase several properties immediately downstream of the dam, and institute a telephone-dialing system to warn residents of dam failure. It is expected that Dungowan Dam's risk rating would have improved as a result of these initiatives, but pumped hydro could wipe out all these expensive gains by placing hundreds of workers' lives at risk.
The individual risk rating is based on the "individual most at risk" in the worst-case scenario of dam failure. In 2013, Dungowan Dam scored an unenviable individual risk rating of 3.4E-5, which is about 430 times higher than Chaffey Dam's rating of 7.91E-8. Again it is expected that Dungowan Dam's individual risk rating today would be much lower after Council's multi-million dollar improvements. If pumped hydro goes ahead in our valley, the "individual most at risk" would probably be one of the 500 construction labourers living and working along Dungowan Creek - and Dungowan Dam's individual risk rating would likely soar again.
No matter how you look at it, EDF's plans for pumped hydro along Dungowan Creek are a negative for locals and for Tamworth. Say no to the Dungowan PHES.