Frequently asked questions

The proposed realignment of the road will increase the distance travelled by road users by approximately 3.7km (two minutes at the current speed limit). The construction of the new sections of Panuara Road will be undertaken while maintaining use of the existing road. There will be times when traffic control will be in place when the new sections of road are joined to the old sections.

The map below shows early suggested options (1a and 1b), and, following community feedback, the current plan (1c) for the proposed realignment of Panuara Road.

The proposed realignment for Panuara Road has been changed several times based on community feedback. Three options were presented at the announcement of CCOP with majority feedback at the time indicating Option 1 was preferred. Further refinements to the proposed realignment continued, with Option 1A presented to the community in May 2023 and Option 1B presented to the CCOP residents workshop in March 2024. Further refinements have since been undertaken to:

• Firmly situate the road to the west of the ridgeline to separate the proposed road from Errowanbang;
• More closely align the road with the existing Meribah Rd in the east; and
• Minimise impact to sensitive vegetation and cultural areas.

Further detailed design will be undertaken to optimise the intersection of Panuara Rd with Cadia Rd.

Feedback gained from community members at community meetings, workshops and face-to-face conversations have influenced the proposed design. Understandably, requests have been made to align the design as close to the Cadia mine site as possible. It has taken time to seek feedback on proposed options as well as aligning the proposals with the Australian Standards for roads. The result is a realignment design that reduces visual and noise impacts for nearby residents, minimises vegetation removal and avoids impacts on culturally significant objects, such as scar trees.

The Panuara Road realignment continues to be revised following the recent workshop and feedback on the alignment. Further detailed design will be required to ensure the road (including the intersection design with Cadia Rd) meets the required Austroad design guidelines.

The design and planning of the road construction will ensure access will be available at all times for Emergency Response traffic.

No, Flyers Creek will not be impacted by the Panuara Road realignment.

The construction work will be carried out during the day with minor impact on local residents, as you would expect for any construction works on any project. The changes, including how it will operate once it’s in place, have been factored into the inputs for the EIS assessments, and will form part of the impact assessment outcomes which will be shared with community prior to EIS submission.

A Visual Impact Assessment will be carried out for the project, including for the Panuara Road realignment. A number of visual montages have been prepared for locations around the mine showing the visual impact of the proposed Southern Tailings Storage Facility (STSFX). Although these do not include the road, there will be an assessment made in relation to the visual impacts of the road.

The proposed Panuara Road realignment has undergone refinement. Once a few small details are sorted out pegs will be installed for viewing. Local residents will then be informed and invited to view and discuss the alignment on site.

Yes, it will be on the western side of the ridgeline separating the road from the Errowanbang valley.

In order to meet a higher safety standard for tailings facilities, Cadia is changing from an upstream lift method to a centreline lift. The final embankment design for the existing Southern Tailings Storage Facility (STSF) is larger than anticipated to meet these higher standards, so a small section of Panuara Rd is required to be moved. This change is proposed as part of Modification 15.

As part of the CCOP, Newmont is seeking a separate, more significant change to the alignment of Panuara Road to accommodate the proposed STSFX. This significant realignment of Panuara Rd is part of the planning and approval process for the CCOP and will not commence until approval of the Project is granted by the NSW Government.

Both options are approximately the same distance. They both add approximately 3.7km additional length compared to current Panuara Rd. This could mean an additional 2-3 minutes of travel dependent on vehicle speeds.

A water balance for a mine site is a comprehensive assessment that accounts for all water inputs, outputs, and storages within the mining operation. It involves quantifying water sources, such as licensed extraction from rivers and dams, rainfall, surface water inflows, and groundwater inflows, as well as water uses and losses, including water used for processing, evaporation, seepage and dust suppression.

The purpose of conducting a water balance for a mine site is to ensure sustainable water management practices. It helps Cadia to understand the mine’s water usage patterns, identify opportunities for water conservation and efficiency improvements and comply with regulatory requirements regarding water use and discharge. Additionally, a water balance is crucial for predicting future water needs and ensuring the long-term viability of the mining operation through wetter and drier periods.

Water from the storages onsite is proposed to be used for irrigation. These storages include Upper Rodds Creek Dam (URCD) and the Pit Tailings Storage Facility (PTSF).

The primary control for maintaining a wet surface of tailings which can minimise dust generation is sequenced deposition of tailings. This approach involves strategically layering or sequencing the deposition of tailings around the perimeter of the facility to maintain a wet surface.

By optimizing the deposition sequence, Cadia can reduce the amount of water needed for dust suppression and moisture management. Layers with higher moisture retention properties can help minimize the need for constant water application.

Cadia will be preparing a water balance for the CCOP which will determine the requirements for water across the site and the proposals for future operations under CCOP. This work is still being undertaken and the outcomes will be presented in future workshops and fact sheets.

It is unlikely that Cadia will be seeking additional water licences from river catchments above what is already in place for the operation. Cadia will be preparing a water balance for the CCOP which will outline the current water licences held by Cadia and the proposals for future operations under CCOP. This work is still being undertaken and the outcomes will be presented in future workshops and fact sheets.

The perimeter drain is lined with riprap (rock armour) for erosion protection. Along steep cuts and batters of the drain a non-woven geotextile will be placed beneath the riprap for added protection.

The function of the perimeter drain is to convey construction water, surface water runoff and emergent seepage from the downstream embankment face towards the reclaim ponds.

Cadia routinely monitors and forecasts water efficiency, water supply security and reliability as part of its normal operations. Prolonged drought periods have changed Cadia’s operational practices.

The site water balance reviews enable Cadia to prioritise water re-use over freshwater extraction and to improve water use efficiencies in accordance with the conditions of our approval and our Water Management Plan.

Cadia recognises water as a shared resource. Site water supply is managed with the aim of reducing the demand on high value water sources including the Belubula River. Water supply from external sources is prioritised as follows, subject to available water allocation and on-site storage capacity:

• Priority 1 – treated town effluent from Orange
• Priority 2 – unregulated river and regulated river supplementary and uncontrolled flow events when announced by WaterNSW
• Priority 3 – regulated river general security water from natural tributary flows rather than releases from Carcoar Dam
• Priority 4 – regulated river water from Carcoar Dam releases. Where possible, this extraction is coordinated with WaterNSW to reduce catchment scale transmission losses by combining water orders with downstream water orders.

Cadia maintains a detailed record of site water data which includes:

• Water demand for processing, underground mine operations and other ancillary purposes;
• Water level and stored water volume of water management storages;
• Tailings level of the PTSF, NTSF and STSF (when operational);
• Water transfers to and from water management storages;
• Water transfer to and from underground mine operations;
• Water supply from internal and external sources;
• Environmental flow release from Cadiangullong Dam and Flyers Creek Weir; and
• Total site water storage volume.

The site water records are used to inform:

• Water management decisions made by the Cadia Water Committee;
• Calibration, using models to recreate past conditions and forecasting via the probabilistic site water balance model;
• Calibration and forecasting via the numerical groundwater flow model; and
• Verification of the groundwater inflow predictions.

The site water records are continuously maintained, reviewed and updated to reflect near real-time site conditions.

Information on the results from various monitoring sites is available in Section 3 of this document 12618414-REP-0_Cadia_2022-2023_Surface Water Assessment.docx (caapp.com.au). Monthly samples are taken of water within the PTSF and Upper Rodds Creek Dam (URCD). This data is then independently analysed and forms part of our Annual Review.

The planned capacity for the proposed South Water Storage is 15GL. Studies are ongoing to optimise the design capacity and will be informed by the outcomes of the CCOP water balance.

Cadia will be preparing a water balance for the CCOP which will outline the current water licences held by Cadia and the proposals for future operations under CCOP. This work is still being undertaken and the outcomes will be presented in future workshops and fact sheets.

Cadia will be preparing a water balance for the CCOP which will outline the current water licences held by Cadia and the proposals for future operations under CCOP. This work is still being undertaken and the outcomes will be presented in future community workshops and fact sheets.

The embankment walls and the drains are designed to be highly permeable. The finger drains and collector drains beneath the proposed hydrocyclone sand dam walls are designed to catch and channel all rainfall and water that permeates the sand dam wall out to the external perimeter drains and then flow to the reclaim ponds where the water is pumped back to the process plant for reuse. This is a key aspect of the dam design as it increases the inherent stability of the facility.

The drains beneath the wall are constructed with a gradated crushed rock fill and sized to convey the operational required flow rates both during construction of the sand dam as well as throughout closure. The drains have been designed to have capacity to convey normal operational seepage as well as construction water realised during hydraulic sand placement.

Migration of hydrocycloned sand overlying the drains is controlled by gradational filters and/or geotextiles. The drain rock material has been specified to be sufficiently durable to continue providing drainage of the STSFX through the post-closure asset life. A safety factor is applied to estimated design flows in calculating required capacity of the gravel drains. See typical collector drain and finger drain illustrations below.

The proposed reclaim ponds have been designed in accordance with ANCOLD Guidelines and more importantly have been designed to ensure that Cadia does not release surface runoff water offsite.

Reclaim ponds are fully lined and sized for a flood storage to suit a 1 in 100-year Annual Exceedance Probability (AEP) 72 hr rainfall event. The emergency spillway has been designed for a 1 in 1000 AEP flood and all water storages are actively managed to mitigate the potential for water release outside the site boundaries.

There are five reclaim ponds located around the perimeter of STSFX. The function of the reclaim ponds is to:

• Collect surface water runoff, construction water and flow from the underdrainage system and emergent seepage for transfer back into the site wide water system;
• to manage the risk of the release of water from the Cadia site to the environment.

The reclaim ponds operate collectively to manage the require volumes of water with a total storage volume of approximately 3,450 ML. A recent design change has been proposed which will remove the Reclaim Ponds 1 & 2 and diverts the water previously designed to be captured by these ponds to a larger Reclaim Pond 3. The overall volumes are expected to be similar, however design for this is still in progress and the individual sizing of each pond will be subject to minor changes.

Numerous studies are being undertaken to inform the final design for water storage and usage. Further detailed design is also being undertaken to optimise the reclaim pond and return water pond designs. In addition, Cadia will be preparing a water balance for the CCOP which will outline the current water licences held by Cadia and the proposals for future operations under CCOP including the STSFX and its associated reclaim and return water ponds, the proposed Southern Water Storage dam and all other water infrastructure existing and proposed for CCOP. This work is still being undertaken and the outcomes will be presented in future workshops and EIS Technical Q&A Forums.

Any seepage water from the tailings or the sand wall is collected in drains constructed below the sand wall and directed towards the perimeter drains around the facility and then to reclaim ponds where the water is pumped back to the process plant for reuse.

Cadia mine is designed and managed not to affect groundwater in the region.

Cadia monitors groundwater through an extensive network featuring more than 100 monitoring bores, both on site and across the Cadia district. This network was installed to detect any changes to groundwater levels or quality, with a focus on shallow groundwater interactions with local water resources. All data from this monitoring is shared with the local community and relevant government agencies via the Newmont Cadia website to ensure accountability and transparency. Cadia manages and monitors groundwater in conjunction with independent specialists.

Under our Project Approval and Environment Protection Licence (EPL) there are strict compliance requirements for routine sampling and analysis for water chemistry, which is then reviewed by an independent expert. Findings are shared with regulators including the Department of Planning, the Environment Protection Authority (EPA) and Water NSW and also published on the Newmont Cadia website in our Annual Environmental Review.

In the most recent Annual Review the independent expert concluded that any seepage from the TSF is contained to the immediate TSF area, in compliance with the project approval, and does not have an impact on downstream groundwater water receptors.

CCOP has added to this network of monitoring bores to provide data to support the impact assessments and once approved some of these bores will become a part of the monitoring network.

A groundwater and surface water impact assessment are being undertaken and results will be shared with the community prior to submission of the EIS. CCOP has installed a significant number of new bores in recent years years to provide data to support the impact assessments. We would welcome feedback on any requirement for additional bores.

Yes. Cadia’s Annual Review provides details on water monitoring locations and an addendum to the Annual Review – providing a report on two additional monitoring locations (referred to as BRPS & CAWS71) – was uploaded to the Cadia website 3 June 2024 and can be found at 12640002-REP_Cadia Belubula River surface water assessment.docx (caapp.com.au).

These additional monitoring points have been incorporated into the draft Cadia Water Management Plan currently with the department for approval.

As part of the CCOP EIS process, additional monitoring points have been established:

• CAWS70 – will be added to the draft Water Management Plan to represent the most downstream point on Cadiangullong Creek prior to the junction with the Belubula River.
• CAWS81 – CCOP surface water monitoring point upstream from the Belubula River Pumping station monitoring point.

The data from these CCOP monitoring sites is being used to support the surface water and groundwater impact assessments for CCOP. The results will be shared with community as part of future EIS Technical Q&A Forums and are likely to be incorporated into the Water Management Plan if CCOP is approved.

At this stage the designs for the South Water Storage are less advanced than other areas. The CCOP EIS will assess water requirements for the site and once this assessment is complete the size of the facility will be shared with the community. At this stage we have proposed a facility with a capacity at the upper end of likely requirements to ensure a full assessment of impacts is undertaken.

As part of the Site and Technology Selection process undertaken, Cadia identified a number of sites that were smaller than the capacity required to cater for the proposed life of CCOP. Whilst a combination of these facilities could potentially meet the required capacity, they would create significantly greater impacts on water catchments, biodiversity, agricultural land and community.

Further details can be found in the Southern Tailings Storage Facility Site and Technology Selection Process report on the CCOP website.

The site and technology selection considered the impacts of each site and technology on surface and groundwater systems. A detailed surface and groundwater impact assessment is being undertaken for the proposed Southern Tailings Storage Facility Extension (STSFX) as part of the preparation of the EIS and, when complete, will be shared with the community for feedback.

Newmont has undertaken a detailed assessment of all site and technology options including the Northern option. The assessments were undertaken against criteria including: the impacts on biodiversity, noise and dust impacts, potential impacts on the quality and quantity of impacted water catchments, changes to visual amenity and technical risks.

Based on these assessments and an assessment of technical risk the southern site has been determined to best meet the community's needs.

The community requested that the Department of Planning, Housing and Infrastructure (DPHI) conduct an independent expert review of this selection. The assessment of the experts was that the selection of the southern site was appropriate. The site and technology selection report and the independent experts report are available on the CCOP website.

The assessment of the northern option highlighted two key technical risks:

• The foundations of the facility wall are required to be built on loosely backfilled material. This creates significant difficulty in constructing the wall with the required stability levels to last in the long term.
• The northern site is exposed to significantly larger catchment and larger water flow in Cadiangullong Creek. This creates significant difficulty in ensuring the facility design is not eroded, remains stable, and that the required water quality leaving the facility can be achieved.

The proposed Southern Tailings Storage Facility Extension (STSFX) is the nominated site based on Newmont’s site selection report and review by independent expert reviewers. Newmont has been transparent and will continue to engage with the community in relation to the site selection process and the factors that were considered in the site selection process.

Willow Park was acquired by Newmont following its public listing and auction. This property will be managed in accordance with the Cadia Farm Strategy.

Hydrocyclone sand dams are used extensively throughout North and South America and are often used in areas that have very high levels of seismicity and that are located on or near fault lines. The design work conducted to date on the proposed STSFX has fully considered the underlying geology of the site including relevant seismic criteria.

The STSFX has also been designed in accordance with Australian National Committee on Large Dams (ANCOLD) Guidelines. Specific design criteria have been adopted in relation to seismicity. From a seismic perspective, a Cadia Mine Seismic Hazard Assessment and Time History Analysis study was undertaken by the Seismology Research Centre for the Cadia site in November 2019. The data from this analysis has been used to inform the design of the STSFX facility under normal operating conditions and post-seismic loading conditions.

There have been several geological studies across the Cadia site including the tailings storage facilities. Geotechnical drilling campaigns conducted over the ground nominated as the footprint for the STSFX to understand the geotechnical conditions have informed the designs to date. Further geotechnical drilling is planned.

The Southern Tailings Storage Facility Extension (STSFX) is planned to manage approximately 650 million tonnes (Mt) of tailings over its life. This includes an area to store excess sand which may ultimately contain 90Mt of excess sand. Cadia is continuing to look at further refinement options in order to reduce this volume of excess sand stored and how it plays a role in early rehabilitation where feasible.

Work is continuing on the refinements to the design of the STSFX and how it integrates with the existing NTSF and STSF. We will share these with the community in future CCOP Forums.

As a key part of the site selection process, a range of potential tailings deposition technologies were investigated across six potential shortlisted TSF sites.

The technologies considered over the multiple studies included:

• Conventional (thickened) slurry – as currently used at Cadia across all current TSFs
• Central thickened discharge;
• Paste;
• Dry stack (filtered tailings);
• Co-disposal of coarse mine waste (cobbles and boulders) with slurry;
• Co-mingling (tailings and coarse waste rock are mixed together within a storage facility or as a single discharge stream);
• Hydrocycloned sand wall embankment.

Hydrocycloning of the tailings waste separates the coarser tailings fraction, hydrocycloned sandfrom the finer tailings, providing a coarse sand material for construction of the new Tailings Storage Facility embankments.

Once separated, the coarse sand (hydrocyclone underflow) is delivered to and hydraulically deposited into cells on the embankment for compaction. The finer fraction is discharged into the facility behind the progressively raised embankment. Water is collected and returned to the process for reuse.

Hydrocycloning of tailings was developed in the 1960s and continues to be used globally as a safe and reliable method of embankment construction.

Hydrocylone sand dams have only recently been explored as an option in Australia. Previously considered construction methods such as upstream lifts are no longer considered acceptable. Cadia’s own experience has highlighted that it is no longer an acceptable design practice. Hydrocylone dams are considered leading practice around the world as an inherently better design, however they are new to Australia and change can take time. Cadia will lead Australia to a better benchmark.

Hydrocyclone sand dams are used extensively throughout North and South America and are often used in areas that have very high levels of seismicity.

The current existing STSF area (including embankment walls) is approximately 500 hectares. The additional surface area of the STSFX at the end of its life (2048-2050) is approximately 650 hectares. The wall height when it reaches its final height will be the same as the current NTSF and at the end of its life will vary around the perimeter from around 30m on the eastern side of the facility to between 60 and 80m on the western side of the facility. Similar to the STSF at the highest point in the southwest in the area of Rodds Creek the wall height from natural ground level is approximately 150m.

Due to the nature of its construction the STSFX is expected to generate less noise and light emissions than existing construction techniques for the tailings facilities at Cadia. Sand will be pumped to the dam wall where it is constructed using either cell construction or downslope construction.

Sand material and the fine tailings will be pumped from the process plant to the STSFX.  The sand is deposited as a slurry within constructed cells or directly downslope of the crest. From there dozers are used to push the sand around and compact the surface. This is a considerably smaller fleet than the traditional carting and dumping of rock being used on the existing facilities. For the early construction of the starter embankment which is constructed with rock materials the fleet is expected to be similar to the existing construction techniques.

The hydrocyclones that separate the tailings into coarse sand for construction of the sand embankment wall and the fine tailings will operating 24 hours a day. The sand is deposited as a slurry within constructed cells or directly downslope of the crest is in line with the operation and pumping of tailings to the NTSF and STSF. Dozers and other heavy mining equipment are used to manage the facility and compact the surface. This heavy mining equipment will operate during the day only, as is currently the case for the NTSF and STSF.

In May 2023 we showed the community pictures of the most common practice of cyclones on the wall of the dam. We received clear feedback that this was not acceptable to the community. In response, we first considered relocating the cyclones and pumps to an enclosed facility adjacent to Cadia Rd. Whilst this was an improvement, we have explored alternatives and will now be moving to a facility adjacent to the Cadia Concentrators to minimise the sources of noise and light from the areas around the STSFX.

A detailed geochemical assessment is being undertaken for the both the proposed coarse tailings and fine tailings streams that are produced for the cyclone sands dam. The preliminary results of the assessment indicate that the tailings and sand is non-acid forming (NAF). Further updates will be available once this work is complete.

Groundwater and surface water impact assessments are being undertaken and results will be shared with the community prior to submission of the EIS at a future EIS Technical Q&A Forum. This groundwater impact assessment will consider seepage from the TSF and also transport of dissolved matter through the tailings.

Dust management for the proposed hydrocyclone sand dam includes:

• For the tailings area the primary method for controlling the surface moisture content is the sequenced deposition of tailings. This approach involves strategically layering or sequencing the deposition of tailings around the perimeter of the facility to dampen and maintain a moist surface;
• For the STSFX it is also proposed to include a sprinkler system on the crest of the dam covering portions of the tailings beach from the dam wall for contingency irrigation and difficult atmospheric conditions (hot, dry or windy weather);
• For the sand wall it is proposed to install wind breaks with progressive rehabilitation where advancing the downstream slope of the wall slope has progressed. We are currently investigating using a downslope up approach to enable progressive rehabilitation on the eastern wall of the TSF;
• Consideration will also be given to temporary erosion protection measures for inactive areas during construction/operation including: (seed + mulch + fertilizer + dye, currently in use on STSF), mechanical planter (seeding), synthetic protective solid covers (e.g. geotextile), synthetic protective covers (polymers/sprays).

Cadia is also undertaking additional testing to identify optimal environmental conditions, moisture content and wind conditions that minimises dust lift of tailings and sand. This will enable the operation to proactively respond to the conditions to ensure adjustments to the operations can be made to reduce impacts, such as turning on irrigation sprinklers ahead of a hot dry spell.

As part of the ongoing study into hydrocyclone sands, a pilot plant for cyclone sands has been established to test the process of creating the sand of the correct specifications required for the construction of the cyclone sand wall. The test results show that the correct sand specification for sand dams can be delivered for the proposed STSFX.

The outcomes of the trials are critical to the design development of sand dams and have informed the specific technical details for the wall and tailings impoundment concept design for the STSFX. A consolidated report of the trials was provided to DPHI for their review and has been uploaded to the CCOP website. The Tailings Pilot Plant Phase 2 Trials Consolidated Report can be found on the CCOP website.

A further larger scale trial has been proposed to be carried as part of the Modification15 submission to provide further data to support the engineering design of the facility. Community members will be invited to attend whilst this facility is in operation.

While detailed comparisons of rock quantities between the hydrocyclone sand dam and dry stack technologies have not been made, it is expected that volumes of rock required would be comparable. Both options require rock in the initial construction of starter embankments, and for construction of filter drains and other associated infrastructure.

There are many sand dams in operation around the globe including at various copper/gold mines in both North and South America. Newmont's Peñasquito Polymetallic Mine has a sand dam and produces gold, silver, zinc and lead. Newmont also operates the Red Chris copper-gold mine which also has a sand dam.

A detailed geochemical assessment is being undertaken for both the proposed coarse tailings and fine tailings streams that are produced for the cyclone sands dam. The preliminary results of the assessment indicate that the tailings and sand are non-acid forming (NAF).

The proposed design includes many features to address seepage from the facility. The role of the seepage control system is to minimise losses of construction water, process affected and final tailings pore water into the foundation (and therefore, regional groundwater).

For the STSFX this will be achieved using a system comprised of several seepage mitigation design (SMD) elements.

The SMD components included in the seepage control system are:

• Hydrocycloning of the whole tailings to remove the sand fraction (resulting in lower permeability for the STSFX final tailings compared to those stored within the existing TSFs);
• An underdrainage system beneath the hydrocycloned sand embankment to collect construction water from the hydraulically placed sand and emergent foundation seepage upstream of the embankment toe;
• A perimeter diversion drain beyond the downstream toe that will collect shallow foundation seepage;
• Reclaim ponds (plus the Return Water Pond) downstream of the STSFX embankment that will capture runoff and emergent seepage;
• Clay and geomembrane lining where appropriate;
• A positive foundation cut-off trench through residual soil and extremely weathered rock beneath the upstream toe of the starter embankment;
• Provision for foundation/fault grouting if relatively permeable zones are identified during the proposed Phase 3 site investigation.

Newmont acknowledges the catastrophic impacts of both Mount Polley and Brumadinho tailings dam failures. However, it is important to note that neither dam was a hydrocyclone sand dam. Brumadinho was also an upstream raise construction method that is no longer used in new dam constructions. Mount Polley was a conventional rockfill/earthfill dam, and the failure was attributed to a weak foundation failure.

The proposed STSFX is a centreline/downstream raise construction methodology. The STSFX has been designed in accordance with Australian National Committee on Large Dams (ANCOLD) Guidelines. Specific design criteria have been adopted in relation to wet weather events and seismicity.

For wet weather events Flood Storage Compartments within STSFX are shown in the figure below.

The design criteria for each storage compartment are shown in the table below.

There are cumulative storm water storage allowances provided for in the design. There is excess water storage within the STSFX during all stages of development, indicating that the flood storage requirements are able to be met. The maximum operating level is the decant pond level at which deposition is required to cease.

From a seismic perspective, a Cadia Mine Seismic Hazard Assessment and Time History Analysis study was undertaken by the Seismology Research Centre for the Cadia site in November 2019 (Seismology Research Centre 2019). The data from this analysis has been used to inform the design of the STSFX facility under normal operating conditions and post-seismic loading conditions.

The slope of the embankment wall is 3.5:1. This means for every 1 metre increase in height, the horizontal length would go out to 3.5m This has been benchmarked against hydrocyclone dams across the world.

The design of the sand dam wall is permeable to allow the free draining of water from the walls to be collected in drains constructed under the wall. The drains channel the water to a perimeter drain which is collected in reclaim ponds. The water is then pumped back to the process plant for reuse.

A detailed geochemical assessment is being undertaken for the both the proposed coarse tailings and fine tailings streams that are produced for the cyclone sands dam.

The results of this work will be presented in future forums.

The STSFX has been designed in accordance with ANCOLD Guidelines. Designing tailings dams to last in perpetuity post-mining involves considering a wide range of factors to ensure their long-term stability, environmental safety, and minimising maintenance. Some of the key factors considered in the design of STSFX include:

• Geotechnical and Structural Stability:
  • Detailed geotechnical investigations have been undertaken to assess foundation conditions. Geotechnical work will continue to be done as detail design progresses to ensure the geotechnical properties of the foundation soil and rock are well understood.
  • The Seismic Stability: a Cadia Mine Seismic Hazard Assessment and Time History Analysis study was undertaken by the Seismology Research Centre for the Cadia site in November 2019 (Seismology Research Centre 2019). The data from this analysis has been used to inform the design of the STSFX facility under normal operating conditions and post-seismic loading conditions.
  • Slope Stability: Ensuring stable slopes for both the dam and the surrounding terrain, using appropriate angles and reinforcement where necessary.
• Water Management Considerations:
  • The STSFX has been designed with a key focus on water management and management of seepage mitigation.
  • The water management systems include:
    • Hydrocycloning of the whole tailings to remove the sand fraction (resulting in lower permeability for the STSFX final tailings compared to those stored within the existing TSFs);
    • An underdrainage system beneath the hydrocycloned sand embankment to collect construction water from the hydraulically placed sand and emergent foundation seepage upstream of the embankment toe;
    • A continuous 1 to 10 m deep perimeter diversion drain beyond the downstream toe that will collect shallow foundation seepage;
    • Reclaim ponds (plus the Return Water Pond) downstream of the STSFX embankment that will capture runoff and emergent seepage.
    • Maintaining a central decant pond within the STSFX (reduces gradients near the embankment crest).
  • Rehabilitation and closure design forms a key part of creating a safe and sustainable landform post-mining. A detailed rehabilitation strategy will be developed for the CCOP.
  • Long-term monitoring and maintenance:
    • Instrumentation: installing monitoring equipment to track the dam’s performance over time, including measuring stress, strain, seepage, and other critical parameters.
    • Regular inspections: conducting periodic inspections to identify and address any issues early.
    • Adaptive management: adjusting management practices based on monitoring data and new insights.
  • Case studies and historical data
    • The STSFX design has taken into account the latest research and technological advances into the hydrocyclone dam designs and has been benchmarked against several cyclone sand dams around the globe including those at current Newmont operations.

The design of the sand dam intentionally allows air and water to infiltrate the wall. The wall is permeable to allow the free draining of water from the walls to be collected in drains constructed under the wall. The drains channel the water to a perimeter drain which is collected in a reclaim pond. The water is then pumped back to the process plant for reuse.

The sand dam wall is a free draining wall. It is not a concrete consistency.

As part of the Site and Technology Selection process Cadia considered the use of the voids created by the subsidence zones over both Ridgeway and Cadia East underground mines. While underground mining is still in progress, the safety issues associated with depositing tailings, whether thickened or unthickened over working areas of the mine is unacceptable to Newmont.

The sand is pumped to embankment wall as a slurry. As the sand settles and is compacted in the wall, the water freely drains out of the embankment wall and is captured by the underdrainage system beneath the wall. The drains capture the water and direct this to a perimeter drainage channel which takes the water to the reclaim ponds from where it is pumped back to the process plant for reuse.

Newmont will prioritise the control of dust. Meeting the obligations laid out in CCOP is vital to us as a business and vital to the community. Reducing production would form part of a range of responses to meet that commitment and will occur if required.

Cadia tests water to assess for environmental contaminants that could be of concern above certain site-specific guideline values such as pH, electrical conductivity (i.e. salinity) and also for heavy metals.

There have been some studies undertaken into alternate uses for tailings including a University of Queensland study that did some early investigation into the use of tailings in the manufacture of bricks. Cadia will continue to investigate further developments on alternate uses for tailings in the future.

We understand that this is an important topic for the community and nearby landholders. The risk assessment requires a number of other studies to be completed. We will provide an update on this risk assessment later in 2024.

Newmont is a signatory to the GISTM and is committed to its implementation. Newmont communicates progress towards this standard annually in August. The STSFX is being designed to meet GISTM standards.

The Newmont tailings management website provides background information on GISTM and Newmont’s approach to safe tailings governance. (Newmont Tailings Governance) GISTM requires meaningful engagement on tailings management which, for new/expanding facilities, includes discussing design options and incorporating/considering feedback and concerns into the decision-making process.

The Newmont tailings management website includes details on Newmont’s tailings governance systems and processes. This can be found here.  The Accountable Executive in Newmont is the Chief Technology Officer.

Cadia uses appropriate experts for its facility designs. These designers have the appropriate qualifications and experience to lead the design of the facilities. Newmont also utilises an independent tailings review board composed of subject matter experts to assist in providing appropriate technical governance as part of the wider governance processes for tailings facilities. The Engineer of Record will prepare and approve the final design prior to construction commencing.

Newmont has a site-specific responsible tailings facility person on each site, supported by enterprise level subject matter experts, operational teams and an independent technical review board.

A detailed geochemical assessment is being undertaken for the both the proposed coarse tailings and fine tailings streams that are produced for the cyclone sands dam. The preliminary results of the assessment indicate that the tailings and sand is non-acid forming (NAF) and is currently being independently reviewed. The results of this work will be presented in future EIS Technical Q&A forums.

We understand the request, it’s been six years since the slump, getting it right is taking more time than we had anticipated. The design of the repair needs careful and diligent work as well as independent oversight from experts. The designs for the NTSF Western and Eastern walls have been completed and these areas have also had their embankment buttressing work completed. An update on the remainder of the NTSF wall repair will be provided to community as soon as it is complete.

The CCOP EIS will provide an updated assessment of the impacts associated with the proposed extension of life of the operation and of the associated infrastructure such as the extension to the Southern Tailings Storage Facility Extension (STSFX), Southern Water Storage Dam, realignment of local roads and increased mining activity in Ridgeway Mine and Cadia East.

The update assessments will include:

• CCOP EIS | Air Quality Impact Assessment
• Assessment of Commonwealth Matters Report
• Cadia LOMT | EIS | Wind Tunnel Analysis
• CCOP EIS | Peer Review of Hydrogeological Conceptual Model Review and Update’
• CCOP EIS | Aboriginal Cultural Heritage Assessment
• Aboriginal Cultural Heritage Assessment
• Air Quality Impact Assessment
• Aquatic Ecology Assessment Report
• Biodiversity Assessment Report
• Bushfire Assessment
• Economic Impact Assessment
• Flood Study and Risk Assessment
• Greenhouse Gas Assessment
• Groundwater Impact Assessment
• Hazard Assessment
• Human Health Risk Assessment
• Land and Agriculture Impact Assessment
• Landscape and Visual Impact Assessment
• Noise and Vibration Impact Assessment
• Rehabilitation Strategy
• Social Impact Assessment
• Surface Water Impact Assessment
• Tailings Geochemistry Assessment
• Traffic and Transport Impact Assessment

Cadia is investigating options for permanent noise monitoring locations and have signalled Newmont’s intention to adopt noise monitoring in Cadia’s submission into the EPA’s Environment Protection Licence review. Currently long-term noise monitoring is being undertaken at locations close to the TSF in relation to the TSF construction works to the east and west of the operation.

A full noise impact assessment will be conducted as part of the EIS. A number of changes have already been made to the project following feedback from community. The hydrocyclones that separate the tailings into coarse sand for construction of the sand embankment wall and the fine tailings that is stored are now proposed to be located at the main process plant following community feedback and assessment by the engineering team. This reduces the noise impacts to the community.

CCOP continues to work on the project details to minimise impacts on biodiversity and agricultural land where possible. Detailed land and biodiversity impacts will be included in the impact assessments for the EIS and the outcomes of these assessments will be shared in future Technical Q&A Forums.

As part of the EIS an Aquatic Ecology Assessment will be undertaken which includes taken a number of samples from the bores on site. This assessment is still in progress and the findings will be shared with community at a future Technical Q&A Forum prior to submission of the EIS.

A detailed Noise Impact Assessment will undertaken for CCOP and a mitigation plandeveloped. Cadia is not seeking any increase in noise limits above our current approvals. The outcomes of the impact assessments will be shared with the community before the EIS is submitted.

Cadia will be preparing a Noise Impact Assessment as part of the preparation of the EIS for the project. This assessment is still in progress and the outcomes of the assessment will include recommendations for mitigation and management measures for affected properties. Once the results of the assessments are known Cadia will engage with potentially affected properties to explore measures to mitigate any impacts.

Cadia is committed to maintaining air quality within the required limits of 50 micrograms per cubic meter of Particulate Matter (PM) 10 and 25 micrograms per cubic meter of PM2.5 for any 24-hour period to assist in minimising the impact that our activities could have on the local community and the environment.

To maintain openness and transparency, we have launched a dedicated real-time monitoring page to display air quality levels around the clock at four strategic locations on and around our site. To view real-time data displayed from Cadia’s monitors, click here  Live air quality monitoring.

The NSW Government also reports air quality data from various monitoring stations across the state, including monitors located at Errowanbang, Forest Reefs and Millthorpe. To view real-time data displayed from NSW EPA monitors, click here Air Quality NSW

The Air Quality Impact assessment being conducted considers all available baseline data across the project area and data available from Cadia monitoring sites as well as EPA monitoring sites.

The assessment will also include the improvements made by Cadia over the last 12 months including:

• Installation of a $14 million centre pivot irrigation system on the Northern Tailings Storage Facility;
• Installation of additional dust extraction units;
• Additional monitoring of vent rise emissions;
• Installation of additional dust sampling instrumentation in the underground mine.

Cadia is committed to maintaining air quality within the required limits of 50 micrograms per cubic meter of Particulate Matter (PM) 10 and 25 micrograms per cubic meter of PM2.5 for any 24-hour period to assist in minimising the impact that our activities could have on the local community and the environment.

To maintain openness and transparency, we have launched a dedicated real-time monitoring page to display air quality levels around the clock at four strategic locations on and around our site. To view real-time data displayed from Cadia’s monitors, click here  Live air quality monitoring.

The NSW Government also reports air quality data from various monitoring stations across the state, including monitors located at Errowanbang, Forest Reefs and Millthorpe.

A noise and vibration impact assessment will be conducted as part of the preparation of the EIS. Cadia is not seeking any increase in vibration limits above our current approvals. Once the outcomes of this assessment are complete the findings will be shared with the community at a future EIS Technical Q&A Forum.

A detailed Historic Heritage assessment is being conducted as part of the Environmental Impact Statement (EIS) preparation and will include how the project proposes to mitigate impact to identified heritage sites. When this is available we would welcome comments on how it could be improved based on local heritage knowledge.

CCOP will prepare the Historical Heritage Assessment report to identify important sites including structures. A Noise and Vibration Assessment will also review potential impacts to surrounding properties and structures.

The preliminary findings from the Historical Heritage studies and the Noise and Vibration Assessment will be shared with the community at an EIS Technical Q&A Forum. The final investigations from these studies will be shared with the community as part of the preparation of the EIS phase of the Project.

The Historical Heritage Assessment will seek to identify potential impacts. If required Cadia will strengthen or otherwise modify existing structures at its expense to withstand any adverse impacts from vibration caused by Cadia.

The CCOP team has undertaken two rounds of field investigations with Registered Aboriginal Parties (RAPs) and has prepared a draft of the Aboriginal Cultural Heritage Assessment Report (ACHAR), which has been shared with the RAPs.

A culturally sensitive summary outlining the study methodology, approach and preliminary findings of the investigations will be shared with the community at the EIS Technical Q&A Forum. Newmont will also conduct a Cultural Values Assessment in the coming months and will finalise the ACHAR once all feedback has been received from the RAPs.

The Human Health Risk Assessment (HHRA) is one of the final assessments that will be completed as part of the EIS. This is because the HHRA requires outputs from a number of different studies including noise, air quality, surface water and ground water, aquatic ecology and geochemical assessments.

As these studies are still in progress the HHRA will be undertaken once the outputs from these assessments have been completed. We anticipate the HHRA will be finalised in October 2024.

A visual impact assessment is a requirement of the EIS submission and CCOP is currently undertaking a Visual Impact Assessment for the project. In addition to this we have shared with nearby neighbours montages of the project from individual private properties and will continue to work with neighbours to address the visual aspects of the project.

As part of the preparation of the EIS, Cadia is required to undertake a Visual Impact Assessment (VIA). The outcomes of the VIA will be shared with the community ahead of the exhibition of the EIS. Preliminary observations indicate minimal additional impacts from night-time lights from the operation over and above those being currently experienced.