ABOUT TAILINGS STORAGE
Tailings is the finely ground rock 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 stored in tailings impoundments. Waihi’s tailings impoundments are carefully
engineered rock structures that are designed to withstand significant seismic and weather events. They are made up
of several separate layers and are designed to the same specifications as a water-retaining structure.
The tailings from the Waihi mines are stored in tailings impoundments. Waihi’s tailings impoundments are carefully
engineered rock structures that are designed to withstand significant seismic and weather events. They are made up
of several separate layers and are designed to the same specifications as a water-retaining structure.
TSF 3 CREST RAISE
The current TSF1A and TSF2, and the proposed TSF3, have insufficient capacity for the tailings volume from processing ore from the Martha Pit.
To accommodate the additional required tailings capacity, OceanaGold Waihi is proposing to raise the crest of the proposed TSF3. A lift can be achieved by steepening the slopes at the crest and reducing the TSF dam crest width. The fill
material required for the lift would be obtained from the Martha Pit.
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. 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 Waikato Regional Council after each review.
To accommodate the additional required tailings capacity, OceanaGold Waihi is proposing to raise the crest of the proposed TSF3. A lift can be achieved by steepening the slopes at the crest and reducing the TSF dam crest width. The fill
material required for the lift would be obtained from the Martha Pit.
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. 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 Waikato Regional Council after each review.
TSF REHABILITATION
The outer walls of the embankment will be progressively rehabilitated to pasture. 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 deposit of tailings ceases, it will continue to consolidate, and after a relatively short period of time, water quality in the tailings storage pond will reach a level suitable for direct discharge to the Ohinemuri River.
When the tailings impoundments are finally 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 help maintain water quality.
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 deposit of tailings ceases, it will continue to consolidate, and after a relatively short period of time, water quality in the tailings storage pond will reach a level suitable for direct discharge to the Ohinemuri River.
When the tailings impoundments are finally 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 help maintain water quality.
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