Edgar Dam Strengthening Project

Project Update – February 2024

The project referral (2023/09714) is now open for public comment. For more information, visit Edgar Dam Strengthening Project. Comments close 13 March.

Project Update – November 2023

EPBC referral submitted

The project was referred to the Department of Climate Change, Energy, Environment and Water (DCCEWW) for assessment under the Environment Protection and Biodiversity Conservation Act 1999 on 21 November 2023.

We will update this page as the project moves through the assessment process, including when it opens for public comment. You can also track this via the EPBC Act Public Portal.

For more information about the assessment process, including key steps and indicative timings, please take a look here.

New Quarry selected

The newly licenced Sunshine Quarry (west of Maydena) contains plentiful durable rockfill, so we recently made the decision to go ahead with this quarry for the project. This is a great outcome as it will reduce truck traffic through Maydena and emissions.

Worker accommodation

We continue to work with PWS to explore the feasibility of refurbishing the PWS canteen. If a joint decision is made to progress with these works, a separate approval will be sought. If this idea is not progressed, workers will be based at Edgar Campground as initially scoped.

Project Update – July 2023

Dam Works Permit

Under the Water Management Act 1999, this project requires a dam works permit. Following assessment by NRE Tasmania’s Water Management and Assessment Branch, a permit was granted on 29 May 2023. A request to review this decision has been lodged. More information about the Dam Works Assessment Decision Framework can be found here. An update on the status of this review is expected in August.

Project Schedule and timings

Dam works will not start until all relevant approvals are in place. The original project timeline (as outlined on this site) is no longer achievable given the dam works permit review. At this stage, we anticipate preparatory works on the washdown facility, staff quarters and road improvements will start late this year but works on site are unlikely. This means Edgar Dam campground is likely to remain open through this upcoming summer period. We will confirm this as soon as possible.

Project Update – May 2023

Edgar preparations continue and we’ve got a couple of interesting updates to share.

Quarry Choice

We recently confirmed that the bulk of hard dolerite materials needed to build the new rock buttresses can be sourced from Halls Quarry, just outside of Maydena. Selecting this nearby quarry is a great outcome as it significantly reduces truck traffic through community centres and reduces the project’s overall carbon footprint. We’ll need to continue to bring a smaller amount of specialised materials from Boral Quarry in Bridgewater.

In finalising our quarry choice, potential environmental impacts were a key consideration and our decision was informed by desktop, field and LIDAR surveys.

Washdown Facility

Robust environmental controls are an important feature in all our projects and were a particular focus in this case, given Edgar Dam’s location within Tasmanian Wilderness World Heritage Area.

To stop the spread of weeds and Phytophthora, we will install (subject to final approvals and consent) a permanent biosecurity washdown station at the junction of Scotts Peak Road. The preliminary design for this facility has been finalised and will be included in the upcoming submission for assessment under the Environment Protection and Biodiversity Act 1999. This facility will be made available to other organisations working in the TWWHA, including Parks and Wildlife Service (PWS) and Tasmanian Fire Service, providing an ongoing, positive impact on management of this unique area.

Upgrading critical infrastructure

In consultation with PWS, we plan to upgrade (subject to final approvals and consent) the original Hydro-Electric Corporation canteen and mess-hall which was built in the 1960s and now sits within the PWS operations base on Scotts Peak Road. It will be great to see a piece of Tasmania’s history restored and project staff will be glad to have kitchen facilities and sheltered lounge areas to enjoy during works. In the longer-term, it will provide a hub for workers accessing the south-west region, including track builders, maintenance crews and emergency services.


Project Background

Edgar Dam is one of three dams edging Lake Pedder. Built in 1972, it is part of the mighty Gordon-Pedder scheme, capturing 40% of the water that supplies Tasmania's largest hydro-power station, Gordon Power Station. This station can generate up to 432 MW of electricity or approximately 13 percent of Tasmania's annual energy needs.



Edgar Dam lies next to Lake Edgar fault (see map below from McCue et al., 2003), a crack in the earth's crust that was formed about 540 million years ago. When the dam was built, engineers knew about the fault but in the Australian context, earthquakes were poorly understood and the fault was deemed inactive. Several high-profile earthquakes, including the devastating 1989 event in Newcastle, changed perceptions around the risk of earthquakes and prompted new research at fault sites across Australia, allowing scientists to develop a much more detailed understanding of past and possible future behaviour.



From this new research, Lake Edgar fault was deemed active, although the chance of movement is extremely low. Scientists now believe the fault has had three significant movements in the past 48–61,000 years, triggered by earthquakes of a magnitude 6 and above. The last significant movement was thought to be 18,000 years ago (Swindon et al., 2007; Clark et al., 2011).

Many dams are built and perform safely in active earthquake areas. The key is to appropriately manage seismic risk. What the research highlighted was a new risk that needed additional management - until now, we've managed this risk using post-event controls (safety planning, in-situ monitoring) and this work will permanently improve the dam's seismic resistance. Learn more about managing dam risks in this section.


Project overview

The concrete face on the existing dam wall will be removed (in stages) and gravel filters and supporting rock added to strengthen the internal structure. Before construction, the toe pond (at the base of the dam wall) will be excavated down to the rock to ensure the new structures are built on a solid foundation which will improve stability and drainage. These features will improve the dam wall's capacity to withstand an earthquake. A wave barrier will be added along the top of the dam wall to deflect seiche waves which can form after an earthquake.

This simple, low-impact engineering solution will deliver immediate safety benefits for the community and environment and ensure we are meeting our responsibilities as owners and managers of this asset.

We're currently in the planning phase - learn more about project design, how we've managing impacts, and our forward timeline by clicking the image below


As we progress through to the approvals and construction phases, we'll publish regular updates on this page. Subscribe to get these straight to your inbox!


Questions?

We recognise that Lake Pedder holds significance for many Tasmanians. This project is about delivering immediate safety benefits and will not impact decisions about the future of Lake Pedder. For more information, please take a look here.

Check out the project FAQs or post a question below.

Project Update – February 2024

The project referral (2023/09714) is now open for public comment. For more information, visit Edgar Dam Strengthening Project. Comments close 13 March.

Project Update – November 2023

EPBC referral submitted

The project was referred to the Department of Climate Change, Energy, Environment and Water (DCCEWW) for assessment under the Environment Protection and Biodiversity Conservation Act 1999 on 21 November 2023.

We will update this page as the project moves through the assessment process, including when it opens for public comment. You can also track this via the EPBC Act Public Portal.

For more information about the assessment process, including key steps and indicative timings, please take a look here.

New Quarry selected

The newly licenced Sunshine Quarry (west of Maydena) contains plentiful durable rockfill, so we recently made the decision to go ahead with this quarry for the project. This is a great outcome as it will reduce truck traffic through Maydena and emissions.

Worker accommodation

We continue to work with PWS to explore the feasibility of refurbishing the PWS canteen. If a joint decision is made to progress with these works, a separate approval will be sought. If this idea is not progressed, workers will be based at Edgar Campground as initially scoped.

Project Update – July 2023

Dam Works Permit

Under the Water Management Act 1999, this project requires a dam works permit. Following assessment by NRE Tasmania’s Water Management and Assessment Branch, a permit was granted on 29 May 2023. A request to review this decision has been lodged. More information about the Dam Works Assessment Decision Framework can be found here. An update on the status of this review is expected in August.

Project Schedule and timings

Dam works will not start until all relevant approvals are in place. The original project timeline (as outlined on this site) is no longer achievable given the dam works permit review. At this stage, we anticipate preparatory works on the washdown facility, staff quarters and road improvements will start late this year but works on site are unlikely. This means Edgar Dam campground is likely to remain open through this upcoming summer period. We will confirm this as soon as possible.

Project Update – May 2023

Edgar preparations continue and we’ve got a couple of interesting updates to share.

Quarry Choice

We recently confirmed that the bulk of hard dolerite materials needed to build the new rock buttresses can be sourced from Halls Quarry, just outside of Maydena. Selecting this nearby quarry is a great outcome as it significantly reduces truck traffic through community centres and reduces the project’s overall carbon footprint. We’ll need to continue to bring a smaller amount of specialised materials from Boral Quarry in Bridgewater.

In finalising our quarry choice, potential environmental impacts were a key consideration and our decision was informed by desktop, field and LIDAR surveys.

Washdown Facility

Robust environmental controls are an important feature in all our projects and were a particular focus in this case, given Edgar Dam’s location within Tasmanian Wilderness World Heritage Area.

To stop the spread of weeds and Phytophthora, we will install (subject to final approvals and consent) a permanent biosecurity washdown station at the junction of Scotts Peak Road. The preliminary design for this facility has been finalised and will be included in the upcoming submission for assessment under the Environment Protection and Biodiversity Act 1999. This facility will be made available to other organisations working in the TWWHA, including Parks and Wildlife Service (PWS) and Tasmanian Fire Service, providing an ongoing, positive impact on management of this unique area.

Upgrading critical infrastructure

In consultation with PWS, we plan to upgrade (subject to final approvals and consent) the original Hydro-Electric Corporation canteen and mess-hall which was built in the 1960s and now sits within the PWS operations base on Scotts Peak Road. It will be great to see a piece of Tasmania’s history restored and project staff will be glad to have kitchen facilities and sheltered lounge areas to enjoy during works. In the longer-term, it will provide a hub for workers accessing the south-west region, including track builders, maintenance crews and emergency services.


Project Background

Edgar Dam is one of three dams edging Lake Pedder. Built in 1972, it is part of the mighty Gordon-Pedder scheme, capturing 40% of the water that supplies Tasmania's largest hydro-power station, Gordon Power Station. This station can generate up to 432 MW of electricity or approximately 13 percent of Tasmania's annual energy needs.



Edgar Dam lies next to Lake Edgar fault (see map below from McCue et al., 2003), a crack in the earth's crust that was formed about 540 million years ago. When the dam was built, engineers knew about the fault but in the Australian context, earthquakes were poorly understood and the fault was deemed inactive. Several high-profile earthquakes, including the devastating 1989 event in Newcastle, changed perceptions around the risk of earthquakes and prompted new research at fault sites across Australia, allowing scientists to develop a much more detailed understanding of past and possible future behaviour.



From this new research, Lake Edgar fault was deemed active, although the chance of movement is extremely low. Scientists now believe the fault has had three significant movements in the past 48–61,000 years, triggered by earthquakes of a magnitude 6 and above. The last significant movement was thought to be 18,000 years ago (Swindon et al., 2007; Clark et al., 2011).

Many dams are built and perform safely in active earthquake areas. The key is to appropriately manage seismic risk. What the research highlighted was a new risk that needed additional management - until now, we've managed this risk using post-event controls (safety planning, in-situ monitoring) and this work will permanently improve the dam's seismic resistance. Learn more about managing dam risks in this section.


Project overview

The concrete face on the existing dam wall will be removed (in stages) and gravel filters and supporting rock added to strengthen the internal structure. Before construction, the toe pond (at the base of the dam wall) will be excavated down to the rock to ensure the new structures are built on a solid foundation which will improve stability and drainage. These features will improve the dam wall's capacity to withstand an earthquake. A wave barrier will be added along the top of the dam wall to deflect seiche waves which can form after an earthquake.

This simple, low-impact engineering solution will deliver immediate safety benefits for the community and environment and ensure we are meeting our responsibilities as owners and managers of this asset.

We're currently in the planning phase - learn more about project design, how we've managing impacts, and our forward timeline by clicking the image below


As we progress through to the approvals and construction phases, we'll publish regular updates on this page. Subscribe to get these straight to your inbox!


Questions?

We recognise that Lake Pedder holds significance for many Tasmanians. This project is about delivering immediate safety benefits and will not impact decisions about the future of Lake Pedder. For more information, please take a look here.

Check out the project FAQs or post a question below.

What's on your mind πŸ—£

loader image
Didn't receive confirmation?
Seems like you are already registered, please provide the password. Forgot your password? Create a new one now.
  • Is there an Evacuation Plan in place for the Huon Valley in case of dam failure, and some details would be appreciated.

    Andrew Burgess asked 3 months ago

    Hi Andrew,

    Thank you for visiting the project page and posting a question.

    First and foremost, I would like to reassure you that the risk of Edgar Dam failing is assessed as being extremely low. Nonetheless, in our role as dam managers, we complete extensive risk assessments and manage all identified risks accordingly. In this case, that includes a Dam Safety Emergency Plan and comprehensive monitoring system.

    The monitoring system is similar to those installed at our other dams and ensures Hydro Tasmania is notified as soon as any potential issues arise. For Huon Valley residents, this early-warning system would trigger an immediate notification of any seismic movement, providing a maximum response time for emergency personnel.    

    The Dam Safety Emergency Plan sets out how we would respond if something unusual was detected via our early warning system. This plan is managed in accordance with the requirements of the Emergency Management Act 2006 and State Special Emergency Management Plan (Dam Safety Emergencies) June 2022. Both the Act and State plan emphasise the hierarchy of incident management – and our role is to ensure appropriate state and regional organisations at every management level are fully briefed, so they may in turn plan most effectively for such unlikely events.

    For the Huon Valley, the Huon Valley Emergency Management Committee plays this role, and includes representation from the Tasmanian Fire Service, Tasmania Police, Tasmanian State Emergency Service and Council. We undertake emergency preparedness scenario planning with members of this committee. In addition, all incident management documentation, including flood inundation maps, are provided to the State Control Centre and held securely on the Tasmanian Government’s Common Operating Platform which is accessible to all emergency services personnel.

    Cheers

    Jane

  • During the remedial works will I still have access to either of the camp grounds and be able to use my boat to fish?

    doris.ian asked 11 months ago

    Thanks for getting in touch!

    Edgar campground will be closed during works but nearby Huon and Teds Beach campgrounds (owned and managed by Tasmanian Parks and Wildlife) will be open. All 5 boat ramps at Lake Pedder, including the ramp at Edgar, will remain open.

    Cheers

    Jane

  • I have an idea! Don't strengthen Edgar Dam. Throwing away $21m to fix a dam on a fault line? Really? How many more times will you need to throw away millions of dollars to strengthen it? We should be closely examining the restoration of Lake Pedder, which greatly underpins the values of the Tasmanian Wilderness World Heritage Area.

    Katie asked about 1 year ago

    Hi Katie,

    Thanks for visiting the project site and sharing your views with us.

    Present-day Lake Pedder plays an important role in Tasmania’s energy security and the future of our nation’s transition to a renewable energy future. Lake Pedder is important because its catchment provides a significant 40 per cent of the water that flows through the Gordon Power Station which can generate up to 432 MW of electricity or approximately 13 per cent of Tasmania's annual energy needs. It is Tasmania’s largest power station in terms of both what it can power at any time, in any weather conditions and the total energy it provides in a typical year. More importantly, however, the Gordon-Pedder scheme is one of only two capable of operating during extended periods of dry and still weather, meaning that it is integral for energy security when other storages are low and wind farms cannot operate. This is particularly the case as we face a changing climate because this energy can be accessed quickly to provide critical firming (reliability) to an increasingly variable energy market. 

    Our responsibility at Hydro Tasmania is primarily to generate electricity and ensure our assets operate safely and efficiently. The upcoming work at Edgar Dam is about meeting those responsibilities and completing this project will not influence any government decision about Lake Pedder's future. 

    I hope this provides some context as to why we are undertaking this work. 

    Cheers

    Jane

  • Thanks for the opportunity to comment. Fifty years ago the HEC was advised of community concerns over the construction of an impoundment on top of a known tectonic fault. This project now admits that that risk was real and that substandard dams were built, at least one of which now requires a major reconstruction. The project, as presented, does not mention the other two dams, yet they are hydraulically connected to Edgar Dam, and any seismic shock will be transferred quickly and with little attenuation to both Scotts Peak and Serpentine Dams. HT must have modelled this, so where is the information? Neither does the project address which aspects of seismic perturbation the revised design ams to overcome. Is it the risk of structural damage from earthquake, or from the hydraulic shock, perhaps both? More information is needed. The project does not address the consequences of subverting the original design of the dam: a two-faced design because the dam impounds two water bodies. The fate of Edgar Pond is not mentioned. Will it be drained? or will the extant road bed be used as a coffer dam to contain it? Either of these outcomes will require approval. While the project is stated to be necessary for dam safety reasons, there is no mention of the other dam safety issues that are currently evident. The principal one is that none of the dams has a spillway, or any means of dealing with uncontrolled overfilling that may result from predicted effects of climate change. A secondary dam safety issue is the evident deformation of the Scotts Peak Dam wall and the upwelling that caused it. How will this respond to any seismic shock? In your response to Georgia, you characterise the impoundment as being 'integral for energy security during prolonged drought'. This was demonstrably not the case during the 2015-6 energy crisis. Even though nearly full, the impoundment could not supply water to the Gordon power station because only the top ~10% is physically able to be transferred. The drought-ending rainfall event of February 2016 also highlighted the inability of the transfer infrastructure to move the volume of incoming water to the Gordon impoundment, forcing the emergency opening of the release valve at Serpentine Dam. The value of the Huon-Serpentine impoundment's contribution to Tasmania's renewable energy generation capability is diffused by its cost. The impoundment consumes 240 square kilometres of high-value world heritage land to produce that potential. On the mainland, at Darlington Point NSW, one solar farm and its associated battery produces more power, reliably stored, and grid-formed on about 8 square kilometres of non-world heritage land. Need I use the phrase 'stranded asset'? The best way to mitigate the risk posed by potential seismic activity is to de-water and rehabilitate the impoundment, while taking advantage of the opportunities for modern renewable infrastructure within the Gordon impoundment (which is not part of the TWWHA).

    David Bluhdorn asked over 1 year ago

    Dear David,

    Thanks for sharing your perspective and posing some interesting questions. There was community concern at the time of the initial impoundment, and we recognise the importance of this event in Tasmania’s history. While we can and do reflect on how to do things differently in the future, we can’t change the past. 

    Safety is our number one priority and it is incorrect to claim our dams are substandard – we operate a rolling program of safety review and risk reduction that ensures all our assets meet evolving and increasingly more demanding safety standards. Scotts Peak Dam encountered some cracking, leakage, and settlement at first fill: this was resolved soon after. The other two dams that impound present-day Lake Pedder are in as-built condition and like all our assets, they are subject to safety and risk review, drawing on a range of information, site data and expert advice, including future climate modelling. Edgar Dam is considered our highest risk asset and addressing this safety issue is the driver for this project.

    As you correctly point out, the fault was known at the time of construction – what has changed are evolving safety standards and our understanding of seismicity in Tasmania, the likelihood of fault movement and the potential implications for Edgar Dam. Drawing on this information, we now understand that with a simple, low-impact engineering modification, we can almost entirely remove the seismic risk. 

    You ask about the fate of Edgar Pond – while we will drain, excavate, then refill the small toe pond to complete this work, Edgar Pond will not be drained or otherwise impacted. Like all other aspects of this project, any potential for impacts to Edgar Pond will be reviewed under Federal environmental legislation. 

    Tasmania has a bright renewable energy future that depends on our existing hydropower assets to provide critical firming load, plus increasing wind and solar and exciting emerging technologies. The Gordon-Pedder scheme will play an intrinsic role in this future and this project will ensure we can continue to operate safely.

    Thank you again for sharing your views and we look forward to your ongoing engagement in this project.

    Jane

  • (Oops, I got a bit carried away and forgot to ask the question. See my question at the bottom.) I appreciate the opportunity to comment and the fact you have published some of the questions here for all to see. I contend your point that this work is not a politically influencing factor in the future of Lake Pedder. If we spend millions of dollars of public funds on strengthening the dams now, this is going to make it much more difficult to convince the public to restore Lake Pedder down the track. It is interesting that it is now, when the Restore Pedder movement is gaining momentum, and in fact only shortly after the federal state of the environment report has highlighted Lake Pedder as a potential restoration project that Hydro decides to undertake these works. I understand that Lake Pedder is an important renewable energy asset to Hydro, and therefore to Tasmanians. My understanding is that it provides roughly 4% of the state's power needs. But it’s worth noting that Hydro can only use the top one metre of Lake Pedder's waters for power generation, because of limitations set by UNESCO. After all, the current impoundment is within an internationally recognised world heritage area! I acknowledge that Hydro's responsibility is in providing renewable power. While I agree with this premise, I do ask that Hydro extend their horizon and acknowledge that the flooding of Lake Pedder fifty years ago was a terrible mistake. And now, when there is an opportunity to correct that mistake, Hydro wishes to maintain the status quo and reinforce the dam at a politically crucial moment, in order to defeat the Restore Pedder movement before it's had a chance to really take hold of the world's imagination. I would like to see Hydro Tasmania negotiate with state and federal government on the possibility of restoring Lake Pedder. While the loss of the renewable power from the draining of the lake would be an impact on our power needs, the benefits of restarting the beating heart of the South-West by restoring Lake Pedder would establish Hydro Tas as a world leader in environmental custodianship. It would also awaken hope in the collective subconscious, and demonstrate that it is possible to heal previously degraded natural areas and turn them from economical 'assets' to fully functioning eco-systems once more. What will it take for Hydro to take responsibility for a mistake of the past and to restore what was previously lost?

    Andy Szollosi asked over 1 year ago

    Hi Andy,

    Thanks for getting in touch and sharing your views. 

    We recognise that Lake Pedder holds significance for many Tasmanians and, if presented with the same set of facts in today’s world, the outcome might have been a different one. While we can’t change the past, we are committed to learning and growing as we help forge a new renewable energy future for Tasmania.

    Looking after a large asset portfolio such as Hydro Tasmania’s calls for considerable forward planning – even a small maintenance job can require several years to design, source materials and arrange an appropriately skilled workforce. On top of managing these project logistics, we must also consider the outcomes of our rolling dam safety review program and commitment to continually reduce risk across our business. Given these complexities, we take a 10-year forward plan to scheduling projects, and review and adjust that schedule annually to ensure we’re always addressing the highest priority issues. The Edgar Dam Strengthening Project has been in design and preparation for more than 3 years and now we’re ready to get on and deliver this critical safety improvement. As I’ve highlighted to others on this page, this will not influence future decisions about Lake Pedder. 

    With regards your comments about the management of Lake Pedder, and in particular the water level. Lake Pedder cannot be viewed in isolation from Lake Gordon – together, the two storages play a critical role in our energy market. Lake Pedder is a significant catchment and the 1.5 metres that we use represents an enormous volume of water. The operating rules for Lake Pedder that outline our minimum operating level are self-imposed by Hydro Tasmania, not UNESCO, for operational, environmental and aesthetic reasons. These rules are set out in the Electricity Supply Industry Restructuring (Savings and Transitional Provisions) Act 1995. We could opt to go below this lower level if required – but the benefit of doing so must be considered amongst a range of other factors. In the case of the 2016 energy crisis, it was considered but for various reasons, deemed not to be the best course of action.  

    Thank you again for your feedback – we look forward to your ongoing engagement in this project.

    Cheers

    Jane

  • Could you please publish the cost-benefit analysis? Have you included in your cost estimate all the road repairs and upgrades that will be required for this amount of heavy loads to travel to the site. The damage done by trucks to roads is proportional to the weight of the truck X 2 to the power of 8. Are your estimates based on predicted fuel prices between now and 2025? What will be the greenhouse gas emissions from quarrying, transporting and placing this amount of rock and the manufacture, transport and pouring of new concrete for these works? It may be way more cost effective to drain the impoundment and remove the risk.

    Peter B asked over 1 year ago

    Hi Peter, 

    Thanks for getting in touch. Completing this project will achieve important benefits – for more information, please refer to our new FAQ

    You ask some important questions about the sustainability of the project. Across all our operations, our aim is to minimise our impacts and where possible, repurpose or reuse materials. 

    As I explained in my response to Lindsay (on this page), the materials needed in this project must meet very technical specifications which influence quarry selection. In addition, we excluded quarries that may potentially increase project impacts, for example, sites within the TWWHA or those with biosecurity concerns. While these decisions may increase overall transport costs, they also ensure we avoid impacts which is a priority consideration.   

    Across the project more broadly, we’re exploring a range of opportunities to make the works more sustainable, from recycling the concrete we remove from the dam and using pond sediments to help rehabilitate local areas, to investing in infrastructure that can be repurposed for visitor facilities once the work is done.

    Thanks again for sharing your views. We look forward to your ongoing engagement in the project.

    Jane

  • Why are you destroying bushland and millions of trees when with the climate crisis we need all the trees we can get. Instead of decimating the bush, focus on renewable energy like solar and wind - do not dam rivers/lakes

    123 asked almost 2 years ago

    Thank you for your comment. 

    Please be assured we're not creating new dams or lakes through this work, nor will it result in the destruction of millions of trees. 

    This project focuses on an existing dam that already contributes renewable energy to our system. The works will be largely completed within a footprint of already-disturbed land and we will only clear minimal areas of regrowth vegetation that was recently surveyed to confirm the absence of threatened species. Any vegetation that is removed will be replanted (unless it creates a safety hazard) and in addition, we will look for opportunities to use the sediment removed from the toe pond to rehabilitate damaged areas that still remain from the original construction of Scotts Peak dam. 

    We’ve taken a precautionary approach to managing potential project impacts through careful design and a commitment to sustainability – you can read more about these considerations here https://connect.hydro.com.au/planning-phase

    Cheers

    Jane

  • Thank your for your well presented Project Proposal and the opportunity to ask questions and to comment. I am a Tasmanian ratepayer stakeholder who resides in Queensland and Tasmania, a Land Surveyor originally Registered and Licensed in Tasmania, and an old bushwalker who has climbed many of Tasmania's mountains, including in the South West Wilderness. My submission relates to your Leaving Things Better Program, where firstly I have a few Construction questions. Can you please clarify for me how do gravel filters and supporting rock better manage the new risk? Is the existing broad base of the dam wall (shown in the cross section) not secured on bedrock? If so, how is just the new gravel filter and supporting rock face down to bedrock going to be sufficient to support, during a large earthquake , the remainder of the dam that does not extend to bedrock? I have absorbed all the appreciated information and data you have supplied. If the Edgar and Scotts Peak dams were designed and constructed when the Edgar fault was thought to be inactive, and if because it is now active, the stability of the dams will always be uncertain, even after maintenance, I am thinking IS IT TIME to stop the predicted extensive expense and time on these projects if there can be no guarantee of long term stability and safety of structures because of the over-riding unpredictable geological environment? You state that protecting the environment and managing environmental risks are front and centre, and that every opportunity will be taken to remove or reduce environmental impacts of this project in the TWWHA. However, the flooding of the original Lake Pedder and and the Serpentine River valley had the greatest negative influence on the south west Tasmanian wilderness values. I think the best way to 'Leave Things Better' in the TWWHA will be to Restore Lake Pedder and the Serpentine River Valley biodiversity. Whether or not the Edgar and Scotts Peak dams are ever upgraded, or whether or not Lake Pedder is ever restored, as a bushwalker and someone who has camped at the Huon Campground, I believe that what is very much needed to leave one thing better is to drastically upgrade the toilet(s) and washing facilities there. I will communicate with more detail on Lake Pedder by emailing Engagement Officers Jane and Anneke and the CEO Ian Brooksbank. Again, thank you for the opportunity to respond. Yours sincerely, Lindsay

    Mr Lindsay Hope asked almost 2 years ago

    Hi Lindsay, 

    Thank you for your questions above and your letter which we will respond to separately. 

    Firstly, to your construction questions. The strengthening works will see a permeable filter of sand to fine aggregate placed against the internal material beneath the dam’s concrete face. A coarse filter of larger particles would be supported by a large, heavy cross-section of rockfill, bearing directly on bedrock. If movement occurred, the size, shape and other characteristics of the filter materials would allow them to rapidly move, allowing a crack to “heal”, rather than bridge and remain open. Being supported by the rockfill, the filters would retain the dam’s existing earth fill and, in the extremely unlikely event of an earthquake, allow any leakage to safely flow and provide extended time to address any damage to the dam’s upstream face. Completing the strengthening work will see Edgar Dam’s level of risk reduced to significantly below the level required for a new Australian dam.

    Regarding your suggestion that we should focus our efforts on restoration, please take a look at our new FAQ.

    Finally, with regards to opportunities to leave lasting benefits for visitors, that is something we’re actively discussing with Parks and Wildlife and hope that through this engagement, we’ll gather ideas from visitors like yourself. We will take note of your suggestion to improve facilities at Huon campground and at a later date, we'll share what suggestions we receive and what ideas have been taken on board. 

    Thanks again for sharing your views and we look forward to your ongoing engagement in this project.

    Cheers

    Jane

  • I believe the $21m allocated to this works would be much better spent on the restoration of Lake Pedder. Both the Edgar and Scotts Peak dams are built adjacent to the Edgar fault line. Modern technology and other Earth quakes around Australia have provided concerning evidence that the Edgar Fault is more active than previously estimated, increasing the risk of dam failure and devastating downstream consequences. While dams can be upgraded, the fault line remains in perpetuity. The disturbance the works will create in the TWWHA will affect 2+ summer seasons. It is also simply a waste of money to continue to maintain these dams when they contribute so little to Tasmania's energy and are easily replaceable with other renewable energy projects.

    Katie asked almost 2 years ago

    Hi Katie,

    Thank you for sharing your views on the project. 

    You’re correct that our understanding of Lake Edgar fault has changed over the years since the dam was constructed and as a result, influenced the risk rating of the current Edgar Dam. Scotts Peak Dam is three kilometres west of the fault and not influenced to the same extent. Fortunately, we can adapt Edgar Dam with a simple, low-impact engineering solution that addresses the increased risk posed by the fault and allows us to continue using present-day Lake Pedder to generate renewable energy. For more information, please refer to our new FAQ.

    The project has been carefully designed to minimise impacts, particularly on the unique values of the surrounding TWWHA. While Edgar Dam campground will be temporarily closed while works are underway, visitors will be able to continue accessing all other facilities in the region, including Huon campground and the Edgar boat ramp. A critical consideration in our preparations for this work is ensuring that we can leave lasting benefits, including potentially upgrading visitor facilities or installing new visitor interpretation. If you have any suggestions on how we might leave a lasting benefit, we welcome your input. 

    Cheers

    Jane

  • Dear Manager, I noticed that construction work is starting in a few months on this project, and having just becoming aware of the project, I was wondering when the project was loaded on-line for public input? Maybe I missed something. I'm interested to know if the invitation for input was at an early stage such as during the concept phase or not to facilitate genuine input or it was actually only just loaded to provide information? Regards, Ed Kleywegt (retired civil engineer)

    Ed Kleywegt asked almost 2 years ago

    Hi Ed,

    Thanks for your questions. At this stage, we’re anticipating starting work in late 2023, following consultation with stakeholders and the completion of necessary approvals. As you’d understand, our work to date has been highly technical, with little scope for external input, being focused on ensuring the strengthening will provide the required risk mitigation. We’ve delivered similar works at other sites so we understand the potential impacts which will be avoided by completing the works in a sensitive and appropriate manner.

     Now that we have a near-final design, we’ve recently embarked on engagement for a couple of key reasons:

    1. to raise awareness of the project;
    2. to understand any potential impacts we’ve missed; and
    3. to identify opportunities to shape our approach so that the project delivers long-term benefits.


    For example, we’ll establish a permanent wash-down and disinfection facility to assist government agencies manage biosecurity risks within the Tasmanian Wilderness World Heritage Area. Similarly, we’ll be talking to visitors to the region to understand what campground improvements may be welcomed.

    We welcome your interest in the project and look forward to your continued involvement.

    Cheers

    Jane