We are pleased to share that an Expert Panel has made a final decision to grant approvals for the Waihi North Project.
This project displays OceanaGold’s ability to continue to support economic growth, create high-paying jobs, generate royalties, support communities, and boost exports at the same time as making a positive contribution to the environment.
OceanaGold will now commence the next phase of the Waihi North Project. Several conditions are attached to the project, most of which align with our current operating practices. Our immediate priority is finalising Management Plans that outline how we will meet these conditions. At the same time, we will continue work on the services trench to allow water to be moved between the Willows Road site and our existing Water Treatment Plant which will be upgraded. Construction will also begin on a surface infrastructure area on the farm on Willows Road to support the future commencement of tunnelling works.
The final decision and related conditions and technical documents can be viewed here: Fast-track
This project displays OceanaGold’s ability to continue to support economic growth, create high-paying jobs, generate royalties, support communities, and boost exports at the same time as making a positive contribution to the environment.
OceanaGold will now commence the next phase of the Waihi North Project. Several conditions are attached to the project, most of which align with our current operating practices. Our immediate priority is finalising Management Plans that outline how we will meet these conditions. At the same time, we will continue work on the services trench to allow water to be moved between the Willows Road site and our existing Water Treatment Plant which will be upgraded. Construction will also begin on a surface infrastructure area on the farm on Willows Road to support the future commencement of tunnelling works.
The final decision and related conditions and technical documents can be viewed here: Fast-track
TAILINGS STORAGE
Tailings are the finely ground rock particles left over after the gold and silver have been extracted. A tailings storage facility (TSF) is a structure built for the purposes of storing these tailings and other by-products from the gold and silver extraction process.
The tailings from the Waihi mines are currently stored in tailings impoundments. Waihi’s tailings impoundments are carefully engineered rock structures that are designed in accordance with national and international standards to safely withstand significant seismic and weather events.
OVERVIEW
The current TSF1A, TSF2, and the proposed Gladstone Open Pit tailings storage have insufficient capacity for the tailings volume from processing ore from the proposed Wharekirauponga Underground Mine and Gladstone Open Pit. As part of the Waihi North Project, OceanaGold Waihi is proposing to construct a new tailings storage facility (TSF3) on Company land immediately east of the current facilities, and adding tailings storage within the Gladstone Open Pit.
The tailings from the Waihi mines are currently stored in tailings impoundments. Waihi’s tailings impoundments are carefully engineered rock structures that are designed in accordance with national and international standards to safely withstand significant seismic and weather events.
OVERVIEW
The current TSF1A, TSF2, and the proposed Gladstone Open Pit tailings storage have insufficient capacity for the tailings volume from processing ore from the proposed Wharekirauponga Underground Mine and Gladstone Open Pit. As part of the Waihi North Project, OceanaGold Waihi is proposing to construct a new tailings storage facility (TSF3) on Company land immediately east of the current facilities, and adding tailings storage within the Gladstone Open Pit.
TAILINGS STORAGE FACILITY 3
TSF3 is proposed to be constructed immediately east of the current facilities.
PREPARATION
Geotechnical investigations have identified that TSF3 construction will firstly require material to be stripped from its footprint. This area is about 60 Ha, and the material will be stockpiled on OceanaGold Waihi land close to Trig Road North. It is likely that this material will be used for future rehabilitation work or for use later in the project.
CONSTRUCTION
Rock from within the NRS and TSF3 footprint areas will initially be used to construct TSF3. Temporary quarrying activities would be used to source this material.
Once a starter embankment is constructed, material from the Gladstone Open Pit, and later the already consented Martha Open Pit north wall layback is anticipated to be used for subsequent crest raises of TSF3.
During the initial foundation works, silt control will be provided to avoid dirty water discharging to waterways.
This water may also be pumped to the existing Water Treatment Plant. At a minimum, erosion and sediment control will follow Waikato Regional Council guidelines.
TSF3 construction will involve building an uphill diversion drain, perimeter drains to capture stormwater runoff, and a perimeter road to provide access for operation and maintenance. For operations, a fully lined silt collection pond will be constructed in the lowest area of the TSF3 site. All runoff collected in the pond will be pumped to the Water Treatment Plant. The new collection pond will also include an overflow spillway to the Ruahorehore Stream.
TSF3 will be lined to reduce the potential for any seepage to enter the groundwater system. At the lower levels, TSF3 will be lined with a 1.5 mm thick liner, while at higher levels, a layer of low-permeability, compacted clay is proposed, as is used in the existing TSFs.
EFFECTS
During the initial construction phase of TSF3, we anticipate temporary amenity effects in the area.
If the Waihi North Project is approved, we will be required to manage our activities at TSF3 so that we comply with strict noise and vibration limits, as well as air quality requirements
set through the regulatory approvals process.
OPERATION
All designs and plans are put through a rigorous review process and will need to adhere to all regulatory requirements. If the required consents are granted, the structure will be extensively monitored throughout and beyond its construction phase, and
all monitoring data will be annually collated and reported on. The data and reports will be independently reviewed to ensure the ongoing structural integrity and safety of the structure. The independent review findings will be reported to the Council after each review.
PREPARATION
Geotechnical investigations have identified that TSF3 construction will firstly require material to be stripped from its footprint. This area is about 60 Ha, and the material will be stockpiled on OceanaGold Waihi land close to Trig Road North. It is likely that this material will be used for future rehabilitation work or for use later in the project.
CONSTRUCTION
Rock from within the NRS and TSF3 footprint areas will initially be used to construct TSF3. Temporary quarrying activities would be used to source this material.
Once a starter embankment is constructed, material from the Gladstone Open Pit, and later the already consented Martha Open Pit north wall layback is anticipated to be used for subsequent crest raises of TSF3.
During the initial foundation works, silt control will be provided to avoid dirty water discharging to waterways.
This water may also be pumped to the existing Water Treatment Plant. At a minimum, erosion and sediment control will follow Waikato Regional Council guidelines.
TSF3 construction will involve building an uphill diversion drain, perimeter drains to capture stormwater runoff, and a perimeter road to provide access for operation and maintenance. For operations, a fully lined silt collection pond will be constructed in the lowest area of the TSF3 site. All runoff collected in the pond will be pumped to the Water Treatment Plant. The new collection pond will also include an overflow spillway to the Ruahorehore Stream.
TSF3 will be lined to reduce the potential for any seepage to enter the groundwater system. At the lower levels, TSF3 will be lined with a 1.5 mm thick liner, while at higher levels, a layer of low-permeability, compacted clay is proposed, as is used in the existing TSFs.
EFFECTS
During the initial construction phase of TSF3, we anticipate temporary amenity effects in the area.
If the Waihi North Project is approved, we will be required to manage our activities at TSF3 so that we comply with strict noise and vibration limits, as well as air quality requirements
set through the regulatory approvals process.
OPERATION
All designs and plans are put through a rigorous review process and will need to adhere to all regulatory requirements. If the required consents are granted, the structure will be extensively monitored throughout and beyond its construction phase, and
all monitoring data will be annually collated and reported on. The data and reports will be independently reviewed to ensure the ongoing structural integrity and safety of the structure. The independent review findings will be reported to the Council after each review.
TSF3 REHABILIATION
The outer walls of the TSF3 embankment will be progressively rehabilitated to pasture during and following construction.
This involves applying a layer of subsoil material, followed by a layer of topsoil and then agricultural seed mix. The land will then be grazed by young dry-cattle.
Native trees and shrubs have been planted on various areas of TSF1A and TSF2. These plantings provide a food source and nesting sites for birds. Similar planting is planned for TSF3. Once the deposition of tailings ceases, they will continue to consolidate, and after a relatively short period of time, water quality in the tailings storage pond is expected to reach a level suitable for direct discharge to the Ohinemuri River, as it already has for TSF2.
When the tailings impoundments are later closed, they will be partially capped, leaving a wetland and small pond on the top. The pond outlet structures will allow fish passage from nearby waterways. The ponds will be able to support the range of aquatic organisms typically found in such pond-like environments and wetlands. The riparian planting adjacent to the pond edge will trap sediment and nutrients in the runoff waters and assist in maintaining water quality.
This involves applying a layer of subsoil material, followed by a layer of topsoil and then agricultural seed mix. The land will then be grazed by young dry-cattle.
Native trees and shrubs have been planted on various areas of TSF1A and TSF2. These plantings provide a food source and nesting sites for birds. Similar planting is planned for TSF3. Once the deposition of tailings ceases, they will continue to consolidate, and after a relatively short period of time, water quality in the tailings storage pond is expected to reach a level suitable for direct discharge to the Ohinemuri River, as it already has for TSF2.
When the tailings impoundments are later closed, they will be partially capped, leaving a wetland and small pond on the top. The pond outlet structures will allow fish passage from nearby waterways. The ponds will be able to support the range of aquatic organisms typically found in such pond-like environments and wetlands. The riparian planting adjacent to the pond edge will trap sediment and nutrients in the runoff waters and assist in maintaining water quality.
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