Approximately 58ha would need to be cleared to form the upper reservoir and surrounding infrastructure. 

The footprint of the upper reservoir and surrounding infrastructure would be approximately 58ha. The surface area of the dam itself would be approximately 20ha. This is subject to detailed design. 

No. The project does not have compulsory acquisition powers. The project has been in discussions and negotiations with landowners within the project footprint for several years. Some of the land has already been purchased and options to purchase or options for easement have been signed for most of the project footprint. The project footprint has been revised several times to accommodate involved landowners.

Yes, MPH are aware that the project area may contain threatened flora species including Diuris tricolor (Pine Donkey Orchid). This species would be considered in the Biodiversity Development Assessment Report (BDAR), that would be available online for public review once the project EIS is lodged later this year.

Yes. The environmental consulting firm engaged to complete the EIS has BAM-accredited assessors who are completing a detailed assessment of biodiversity values and impacts in accordance with the NSW Biodiversity Conservation Act 2016 (BC Act) and the Biodiversity Assessment Method (BAM). This would be documented in a Biodiversity Development Assessment Report (BDAR) that would be available online for public review once the project EIS is lodged later this year.

The project is investigating biodiversity stewardship sites adjacent to the project to cover part of the biodiversity offset requirements of the project.

The lower reservoir first fill is proposed to be pumped from the Hunter River, under licence.

Reservoir top ups would be required from time to time depending on seasonal evaporation and rainfall conditions.

The lower reservoir would hold approximately 3.2GL and the upper reservoir would hold approximately 3.3 GL at full supply level.

A pump station is proposed to receive and manage the water from the Hunter River before it is transferred to the project. This is primarily to intercept debris that may be floating in the water. It is not expected that the Hunter River water would require chemical treatment due to the existing water quality being suitable for the pumped hydro system. 

The system is proposed to be in constant operation ie water would be circulating between the reservoirs regularly (with the potential for daily cycling), mitigating the potential for the water to become stagnant. The operational regime of the project is subject to detailed design and market conditions. 

The project is expected to take around 4 to 5 years to construct and commission.

The project is aiming for a cut/fill balance, which means all the material excavated as part of the project would be optimised in the construction of the project, including the upper reservoir embankments, rock fill under both reservoirs, and the access road. An on-site spoil emplacement area has been considered in the project footprint to enable any surplus material to be captured locally in an existing mine void, to save trucking spoil off-site and reduce construction traffic associated with the project.

The upper reservoir would be considered a declared dam under the Dams Safety Act 2015. MPHES would consult with Dam Safety NSW to ensure both the upper and lower reservoirs are designed in accordance with relevant guidelines and legislation and include critical safety mitigation measures to ensure public safety. 

During feasibility studies for the project, detailed options assessments of multiple upper reservoir designs were completed (considering volume, layout, location). The design was refined to reduce potential impacts on the downstream community in the remote event of any dam breach.

The preferred option was selected as it optimised potential power output, maximised reuse of spoil in the formation of the reservoir, and had the least impact on the community in the event of any dam breach.

While the studies from the dam safety experts tell us that the probability of a breach is remote, we take this risk very seriously and the dam would be designed to meet strict engineering requirements and to ensure the risk is as low as reasonably practical. We are also required to comply with State Government regulations through Dam Safety NSW.

As the project is in concept phase, a formal dam break consequence category assessment in accordance with the Dam Safety Regulation 2019 would be completed when the project is in detailed design. Preliminary flood modelling is underway and would be part of the considerations in the Environmental Impact Statement (EIS).  This study would be available to the community and there would be further consultation to help the community understand this information and for us to respond to any issues that are raised.

A recent geotechnical drilling program was completed at the proposed pumped hydro site, designed to target a number of geotechnical faults in the project area, including the Hunter Mooki Thrust Fault and the Aberdeen Thrust Fault. The geotechnical information provides a better understanding of the depth and location of the faults, and the conditions of the rock and material underground. Detailed design of the project would consider these faults and the materials encountered in the drilling program.

The project design, in particular the dam design, contemplates earthquakes and would be built to withstand earthquakes. Stability assessments and settlement assessments have been undertaken, and the design has been adjusted to improve safety in accordance with the Dam Safety Committee NSW DSC3C, Acceptable Earthquake Capacity for Dams. Structural analysis of elements of the dam (including concrete inlet/outlet structures) has been undertaken to ensure the structure performance is safe under earthquake loads throughout the design life of the project.  

The reservoir sites would be fully fenced with a standard safety perimeter fence, with gated security control access point/s. As the water pipelines connecting the upper and lower reservoir and the pump station are underground, they do not require fencing. The substation and the Hunter River Pump Station would have their own compounds with high security fencing.

CCTV surveillance and an intruder alarm system would be utilised as part of the site security system.

The reservoir sites would be fully fenced with a standard safety perimeter fence, with gated security control access point/s. As the water pipelines connecting the upper and lower reservoir and the pump station are underground, they do not require fencing. The substation and the Hunter River Pump Station would have their own compounds with high security fencing.

CCTV surveillance and an intruder alarm system would be utilised as part of the site security system.

Yes. Australia has three existing pumped hydro projects:

• Tumut 3
• Shoalhaven
• Wivenhoe Dam

There are also two pumped hydro projects under construction:

• Kidston
• Snowy 2.0

It is proposed the project would operate, as required to meet the electricity supply demand. 

The project is part of NSW’s renewable energy solution. The project would provide firming power to the grid, providing grid stability when energy demand is high. Firming projects like MPHES have the capacity to deliver electricity to the market when demand is high and/or when renewable energy is not meeting demand.

The power would be sourced from the grid, at times when there is a surplus of renewable energy (ie solar power during the day).

The flow of water downhill through turbines is the process that generates electricity. The water needs to be pumped uphill to create potential energy and then released from the upper reservoir to generate electricity, as it flows back down to the lower reservoir (What is pumped hydro). Water would be pumped back up to the upper reservoir during times when electricity supply is in surplus. This would typically be in the middle of the day due to the increase in solar generation or late night when there is less demand for power.  

The exact amount of electricity required is subject to pump turbine selection and detailed design. As the project is a renewable energy project, it is proposed that surplus renewable energy would be drawn from the grid to pump the water uphill, which would help with stabilising the grid when there is excess supply from rooftop and grid-scale solar during the day. 

Based on our current level of design, we estimate it would take approximately 9.25 hours to refill the top reservoir. This is the time required for the reverse turbines to pump the complete 3.2GL of water required to be pumped from the lower reservoir to the upper reservoir.

This estimate would be refined once the turbine-pump is selected.

Based on the current level of design, the water would travel at around 115 m3/s in generation mode, and around 100 m3/s in pump mode.

The turbines would be reversible pump turbines (which can act as a pump or a turbine).

The water pipeline from the Hunter River would be made from high density polyethylene.  While the underground water tunnels would be constructed of steel and concrete. 

Salt levels are not expected to require any managing.

The lower reservoir would be filled with water from the Hunter River. The Hunter River is a freshwater source that has a salinity trading scheme to manage salinity downstream of Glenbawn dam.

The lower reservoir would be lined with an impermeable liner to maintain the water quality in the reservoir.

It is proposed that the MPHES operation would be a closed-loop system which means the project would be hydraulically isolated from its surroundings, with the water cycled between the upper and lower reservoir and not interacting with any groundwater sources.

There would be a range of direct and indirect employment opportunities during construction and operation of the project.

• Some of the types of direct roles include:
• Project managers
• Construction managers
• Engineers
• Foremen
• Health, safety, environment and quality staff
• Contract managers
• Quantity surveyors
• Administration assistants
• Nurses
• Cleaning staff
• Cooks and canteen staff
• Stores manager and personnel
• Road maintenance crew
• Equipment maintenance crew
• Concrete batching crew
• Gate operators
• Security
• Coach/bus drivers
• Labour
• Trades: Electrical, Mechanical, Technical.
• Scaffolding
• Welders
• General hand
• Maintenance

Some of the indirect employment associated with the project includes:

• Accommodation providers
• Food and beverage outlets
• Recreation and entertainment venues
• Personal care (barbers)
• Plant Hire
• Road Control
• Security
• Consumables

The lower reservoir would have a membrane liner and the upper reservoir would have an integrated lining approach consisting of several lining methods.

The design details would be finalised as part of the ongoing engineering assessments.

The upper reservoir would include a layered lining system of synthetic and natural materials lined with geomembrane.

The lower reservoir would be lined with an impermeable liner to maintain the water quality in the reservoir.

Approximately 440m between the upper and lower reservoirs.

The underground water tunnel system between the upper and lower reservoir is expected to be approximately 2km – 2.5km long.

Traditional Custodians have been engaged during the project development process to inform the Cultural Heritage assessment fieldwork and reports for the EIS. A specific cultural values mapping exercise has also been completed to inform the Aboriginal Cultural Heritage Assessment as part of the EIS. This study involved interviews with Traditional Custodians, during which suggestions were made of how Traditional Custodians could be involved in the Project during construction and operations. This included an interest to be trained in and to work on ecological projects, which could include field assessment, rehabilitation works following construction of the project, and management of the stewardship sites which may be established to offset clearing impacts. Aboriginal Focus Groups held during the EIS preparation phase also suggested skills development and training opportunities to enable local Aboriginal people to become employment ready for the project. These training and education opportunities would be considered as part of a wider Indigenous Participation and Procurement Plan to maximise participation of Traditional Custodians in the project.