Categories
Mining facts

Mining’s Future in a Green Economy

Michael Goehring, CEO, Mining Association of BC discusses mining’s important role in the green economy.

credit: Mining Association of British Columbia

“BC is a hotbed of innovation, so our industry is working closely with BC’ tech sector so we can conserve more, waste less, and reduce our environmental footprint.”

“The minerals and metals that BC produces – copper, silver, gold, steel-making coal, aluminum, molybdenum – they are all essential to a low-carbon future. An electric vehicle takes four times as much copper as a traditional internal combustion vehicle. You can’t make solar panels without silver. And you can’t transmit power from solar panels without copper. Our mineral sand metals are essential to a low carbon future.”

“We now know, in BC, our steel-making coal – which is critical to renewable energy infrastructure – wind mills, for example, has half the GHG emissions intensity as our competitors in Australia. BC’s Copper has about 40-50% less GHG emissions than copper from Chile. Our industry has been reducing its GHGs for several decades. The real driver is our clean energy, driven out of our hydroelectric assets.”

Categories
Exploration

Exploration at Mount Polley

An exploration area at the Mount Polley site called the Frypan/Morehead, located west and north of the mine, covering approximately 3 x 3 kilometres, has recently been the focus of exploration. This area is a largely till covered magnetic high with a similar magnetic response to that obtained over the Mount Polley mine host rock of monzonite and hydrothermally altered monzonite breccia pipes.

A total of 948 soil samples were collected and analyzed using the Mobile Metal Ion technique. SJ Geophysics completed an 80.7 line kilometre Volterra-3D Induced Polarization (IP) survey covering the same grid area. Numerous, high priority targets were outlined.

Another Volterra-3D Induced Polarization (IP) survey was conducted over the Mount Polley mine site to identify the geophysical response of the known mineralization to aid in prioritizing targets on the Frypan/Morehead area. The survey consisted of 81.5 line kilometres and was successful in delineating the known mineralization, as well as outlining several new un-tested areas in the vicinity of the mine.

A drill program is planned to test the geophysical anomalies.

Categories
Monitoring

Mount Polley Environmental Monitoring

Environmental monitoring programs and closure research projects at Mount Polley mine site continue as planned. Remediation construction at the lower Hazeltine Creek and Edney Creek began this summer. Mount Polley staff, with assistance from Golder Associates Ltd., have begun development of the 2022 Water Management Plan.

Monitoring activities include regular water quality and toxicity sampling at:

  • water treatment plant (WTP) 
  • surface waters of Polley Lake, Bootjack Lake, Hazeltine Creek, Edney Creek & Quesnel Lake
  • mine contact waters including groundwater & mine seepage with flow rates

Regular inspections of all critical ditches, sumps, ponds, pumping systems and pipelines.

Ongoing surveys and studies include:

  • spawning activity in Hazeltine & Edney Creeks
  • remediated terrestrial habitats; vegetation growth, nesting sites and wildlife usage
  • aquatic habitats; fish population & tissue, zooplankton, phytoplankton, benthic invertebrates and sediments in Bootjack, Polley & Quesnel Lakes
  • dilution modelling of the Quesnel Lake discharge
  • semi-passive and passive water treatment options for closure which include a constructed wetland treatment system pilot study and a saturated rock fill bench scale test
Tour of aquatic habitat construction in lower Hazeltine Creek
Tour of aquatic habitat construction in lower Hazeltine Creek
Hazeltine Creek Reach One revegetated riparian area
Categories
Remediation

September site tour with the Habitat Remediation Working Group

The remediation of Hazeltine Creek has been planned and advanced through the direct collaboration of Mount Polley mine employees, government agencies, First Nations and their technical advisors. This collective is called the Habitat Remediation Working Group (HRWG).

Recently, members of Mount Polley mine, Golder Associates Ltd, FLNRO (Ministry of Forests, Lands, Natural Resource Operations and Rural Development) and the Xatśūll First Nation attended a September 2020 HRWG tour.

On the tour the HRWG inspected the construction of habitat features in Lower Hazeltine Creek. The group also inspected the weir and fish ladder at Polley Lake, the functioning spawning habitat in Upper Hazeltine Creek and the terrestrial plant growth in Polley Flats.

The group viewed all stages of remediation, from installation of habitat features to a remediated ecosystem in Upper Hazeltine Creek that is maturing into a self-sustaining landscape used by all manners of life forms.

Discussions on the tour included:
• Local nursery plant sources;
• Local contractors support in the remediation efforts;
• Reflections on how far the remediation has advanced;
• Reopening plans for the mine;
• Plans for the continued use of the weir on Polley Lake for flood control and fish rearing in Hazeltine Creek until the plants in the terrestrial flood plain mature; and
• In stream habitat features installed are potentially superior to those that existed pre-2014.

Below are some photos from the tour (September 2020).

Hazeltine Creek Reach One and revegetated riparian areas looking upstream toward Polley Lake.
Hazeltine Creek Reach One and revegetated riparian areas looking upstream toward Polley Lake.
James Ogilvie, Senior Water Resources Engineer at Golder Associates, describes functionality of reconstructed portions of Hazeltine Creek Reach One
Golder Associates Water Resources Engineer explains functionality of reconstructed portions of Hazeltine Creek Reach One
Hazeltine Creek Reach One and revegetated riparian areas looking downstream
Hazeltine Creek Reach One and revegetated riparian areas looking downstream
Categories
Remediation

Remediation continues at Mount Polley Mine site

Please check out this write-up by the Soda Creek First Nations on the remediation work being done at Mount Polley and the tour completed by South Creek Indian Band (SCIB).

Remediation continues at Mt Polley Mine site (PDF)

Categories
Remediation

Experts recommend leaving tailings in Quesnel Lake

Lately we have received questions about the water quality at Quesnel Lake, so here are a few Q&A’s which address this subject.

First, what it means to conduct remediation?

According to the BC Environmental Management Act, “remediation” means action to eliminate, limit, correct, counteract, mitigate or remove any contaminant or the adverse effects on the environment or human health of any contaminant.

At Mount Polley, using the results of the detailed site investigations, and the human health and ecological risk assessments, the goal of the mine’s environmental remediation work is to repair and rehabilitate the areas impacted by the tailings spill such that they are on a path to self-sustaining ecological processes that result in productive and connected habitats for aquatic and terrestrial species.

As the impacts of the spill were determined to be primarily physical and not chemical, this has meant that the focus of the work has been on repairing and rebuilding habitats. 

Where can I find data about the water quality in Quesnel Lake?

The BC government website hosts an interactive map of surface water monitoring sites in the Province which gives access to results of water sampling and analyses, including Quesnel Lake and other surface water sites around the area of the mine. 

Why was the decision made to leave the tailings at the bottom of Quesnel Lake?

Research and monitoring of the physical and chemical stability of the tailings on the bottom of Quesnel Lake indicate that they are not causing pollution and studies of the bottom-dwelling (benthic) organisms have shown that they are slowly recolonizing the lake bottom as native sediment slowly deposits on top of the organic-poor tailings, bringing organic matter to the lake floor. 

After completing a Net Environmental Benefit (NEB) assessment, experts recommended that the best approach for remediation of the tailings in Quesnel Lake was to leave them alone and cause no further disturbance.

The experts determined that any attempt to remove the tailings could significantly disrupt the present ecosystem and set back the progress that had already occurred.

Remediation at Mount Polley is all about creating the conditions for successful natural recovery, and not doing more damage.

Categories
Remediation

Briefing Note on Hamilton et al 2020 paper

The following provides some comments from Mount Polley Mining Corporation (MPMC) on the Hamilton paper (Hamilton, et al. 2020)[1] regarding Quesnel Lake in relation to the TSF Breach at Mount Polley. The note is divided into general comments, specific comments, and then provides an update on Quesnel Lake water quality, and some key observations from recent sediment and aquatic life monitoring, which support the MPMC comments on the paper. This is not a comprehensive review of the paper.

General

The Hamilton paper provides a summary of a considerable amount of monitoring data collected in Quesnel Lake, including  from automated moorings. (Note: MPMC contributed to this research through the purchase of a number of new instruments for the moorings in the fall of 2014.)

The paper focusses on seasonal observations of a slight increase in turbidity deep in the West Basin, and on physical lake dynamics. It also introduces some hypotheses regarding new mechanisms of lake water movement. MPMC is pleased to have contributed to this enhanced understanding of water movements in large lakes.

However, we are concerned that important monitoring data, available on our web site or directly from MPMC or our consultants, was not referred to or incorporated into interpretations made in the Hamilton paper. The use of information that is readily available from MPMC’s web site or directly from MPMC or its consultants would have helped address some of the authors’ concerns, particularly about future impacts to aquatic life and contamination.

Unfortunately, the paper does not include data from the mine’s monitoring nor any other data on these topics. The paper contains a number of interesting scientific observations, but these do not necessarily indicate an environmentally consequential measurement.  

Specific Comments on the Hamilton et al (2020) paper:

  1. Mount Polley’s monitoring data indicates that contaminant levels in Quesnel Lake are not elevated. The paper identifies a small turbidity signal at depth, but turbidity does not necessarily indicate contamination.  (See below for a description of “what is turbidity”.)
  2. Hamilton et al’s data from 2015 to 2017 indicate a significant decline in the seasonal turbidity signal they measured since the spill in 2014. This observation agrees with MPMC’s monitoring data.
  3. The turbidity values measured by both MPMC and Hamilton et al are below BC water quality guidelines, which are based on a 30-day average. (The BC Guidelines allow for increases to 10 NTU for short durations.)
  4. There are no data presented in the paper from 2018, 2019 or 2020. This is a significant shortcoming of the paper being able to speak to the current situation, or to future impacts. MPMC has monitoring data for 2018 to 2020 for a number of sites in the lake that the researchers could have used to assess trends after 2017 for both water quality and aquatic ecosystem health.
  5. The levels of turbidity measured by Hamilton et al deep in the West Basin are quite low. (Between winter 2015 and winter 2017 they range from highs of approximately 2.3 FTU, to less than 0.5 FTU.)  Turbidity is a measure of “cloudiness” due to particulates in water, however, the levels of turbidity being measured in this paper are not easily seen with the naked eye (in other words, instruments are required to measure these levels).
  6. The paper provides background (pre-spill) data that indicate that the turbidity signal they observed at depth is at or below the level of natural turbidity events in the West Basin in the past (for example, a plume from the Horsefly River in May 2008 increased the turbidity in surface water of the West Basin to greater than 2.0 FTU as seen in Figure 3 in the paper). Natural turbidity events, such as are associated with heavy rains, spring freshet (snowmelt) or high-water floods, can generate similar or higher levels of turbidity. This summer, high creek and river levels generated muddy, debris-laden, flows into Quesnel Lake. 
  7. The paper postulates suspension of material from an unconsolidated layer of particulates at or near the bottom of the lake. While the unconsolidated layer identified in core samples is interesting, there is no data in the paper on what the particulates are that make up this layer. MPMC has reached out to the authors with an offer to either do this work on their samples or contribute funding to fill this information gap.  Note that the paper does not say that tailings are resuspending off the bottom of the lake. Note also that MPMC sediment monitoring has observed natural material, with organic carbon, settling into sediment traps placed on the bottom of Quesnel Lake and presumably covering tailings.
  8. There is no data in the paper that indicates that the particulates associated with their turbidity signal are contaminated with any metals or chemicals of concern. MPMC’s monitoring shows that water quality in Quesnel Lake is below the BC Water Quality Guidelines, except during spring freshet when area creeks naturally discharge elevated turbidity and copper.
  9. MPMC supports the Hamilton et al observation of no visible colour change in the lake since 2014. This confirms MPMC’s observations.  
  10. Mount Polley’s water discharge is permitted by the BC Government and is within strict permit guidelines that are protective of sensitive aquatic life. The paper noted a small increase in specific conductance associated with the MPMC treated water discharge in 2016, but also noted that there was no turbidity signal associated with this discharge. These data agree with Mount Polley’s monitoring data. MPMC’s monitoring continues to show that water quality in Quesnel Lake is below the BC Water Quality Guidelines except during spring freshet when area creeks naturally discharge elevated turbidity and copper and when MPMC are typically not discharging because of restrictive permit requirements.
  11. The paper expresses concern about the potential resuspension of spill material from Quesnel Lake and its impacts on juvenile sockeye salmon, while not including data DFO collected on juvenile salmon in the West Basin in 2014, the year of the spill, nor acknowledging that the 2014 juveniles were the cohort that “returned in droves” to the Quesnel Lake watershed in 2018. This juvenile salmon cohort would presumably have been the most impacted as they were feeding in Quesnel Lake the year of the spill, yet there has been no indication that the tailings spill had a deleterious effect on their feeding or their returns four years later.
  12. Mount Polley is very pleased to see that the paper noted that the MPMC remediation of Hazeltine Creek reduced sediment loads as no turbidity signal >0.2 FTU above background was detected near its mouth from 2015 through 2017”.

Quesnel Lake Water Quality

  • There is no evidence of pollution being caused in Quesnel Lake related to the Mount Polley spill. This is affirmed by MPMC monitoring and by BC ENV comments to the MPMC’s Public Liaison Committee.
  • Results of the Comprehensive Environmental Monitoring Program (CEMP) – Sediment and Aquatic Life (Minnow, March 2020) monitoring using DGT instruments in Quesnel Lake indicate:
    • copper concentrations in 2019 “were well below [freshwater aquatic life] effects thresholds”
    • there is “strong evidence of … post-depositional stability of the sediments impacted by the breach”, i.e. there is no indication that metals are leaching out of tailings into the water in Quesnel Lake, and
    • “… analytes in 2019 were all below BCWQG’s”, i.e. all metals analyzed using the DGT’s were below the BC Water Quality Guideline thresholds for protection of freshwater aquatic life.

Discussion of Turbidity from https://lamotte.com/technical-tips/post/turbidity

(website accessed 2020-09-01)

The definition of Turbidity is the cloudiness or haziness of a fluid caused by suspended solids that are usually invisible to the naked eye. The measurement of Turbidity is an important test when trying to determine the quality of water. It is an aggregate optical property of the water and does not identify individual substances; it just says something is there. Water almost always contains suspended solids that consist of many different particles of varying sizes. Some of the particles are large enough and heavy enough to eventually settle to the bottom of a container if a sample is left standing (these are the settleable solids). The smaller particles will only settle slowly, if at all (these are the colloidal solids). It’s these particles that cause the water to look turbid.


[1] Hamilton, A. K., B. E. Laval, E. L. Petticrew, S. J. Albers, M. Allchin, S. A. Baldwin, E. C. Carmack, et al. 2020. “Seasonal Turbidity Linked to Physical Dynamics in a Deep Lake Following the Catastrophic 2014 Mount Polley Mine Tailings Spill.” Water Resources Research 56. doi:https://doi.org/ 10.1029/2019WR025790.

Categories
Community Remediation

Mount Polley built and managed an on-site fish hatchery in 2018

After the spill, a population monitoring program on Polley Lake indicated there had probably been a reduction in the age class of the population of Rainbow Trout (as upper Hazeltine Creek was the main spawning area for these trout). There was spawning observed in Frypan Creek at the north end of Polley Lake, however it was noted to be a much smaller habitat. The Mount Polley Environmental Team (MPET) recognized it was important to allow the fish to spawn in Hazeltine Creek, but the Habitat Remediation Working Group (HRWG) had concerns whether the spawn in the reconstructed Hazeltine Creek would be successful.

The MPET developed a backup plan. With guidance provided by Minnow Environmental and David Petkovich (Aqua-culturist), over 11,000 Rainbow Trout fry were raised in an on-site fish hatchery in spring 2018. Eggs were harvested and fertilized from some of the local Rainbow Trout that had returned to upper Hazeltine Creek to spawn.

The fertilized eggs were incubated in trays so temperature, flow and dissolved oxygen levels could be regularly monitored. Water intake was sourced from below the thermocline in Polley Lake in order to maintain cooler water temperatures.

Egg trays in Mount Polley on-site Rainbow Trout hatchery [2018]
Egg trays in Mount Polley on-site Rainbow Trout hatchery [2018]

Within two months, the eggs hatched into alevins (yolk-sac fry) and within another two weeks the yolk sacs were completely absorbed.  Throughout the incubation stage the eggs were counted, and unfertilized eggs removed.

Fish tray showing Rainbow Trout eggs hatching [June 2018]
Fish tray showing Rainbow Trout eggs hatching [June 2018]
Rainbow Trout fry in shallow ponding tanks [early July 2018]
Rainbow Trout fry in shallow ponding tanks [early July 2018]

The fry were then transferred from the incubation trays to shallow rearing tanks. When the fish reached their target biomass, they were transferred into deeper rearing tanks, and from there released into the Polley Lake watershed.

Mount Polley hatchery rearing tanks. [summer 2018]
Mount Polley hatchery rearing tanks. [summer 2018]

The MPET and Minnow Environmental released over 11,100 Rainbow trout fry from the hatchery into Polley Lake on September 25 and 26, 2018. The adipose fins from each fry were clipped as a means of tagging (identification). On the second day, students, parents and a teacher from Columneetza Middle School’s Greenologists / Enviro Club based in Williams Lake assisted with the Rainbow Trout fry release

Mount Polley strongly encourages Polley Lake fishers to report if they catch fish with a clipped adipose fin to gabe.holmes@mountpolley.com. This will help the MPET determine how successfully the hatchery trout are surviving. Thank you!

Categories
Remediation

Rainbow trout return to Hazeltine Creek

In 2018 a milestone was celebrated by the Mount Polley Environmental Team (MPET) when the efforts of the remediation work rebuilding Hazeltine Creek witnessed the return of Rainbow Trout, Redside Shiners and Long Nose Suckers to the rebuilt part of the creek.

After the August 2014 tailings spill, fish from Polley Lake were prevented from entering Hazeltine Creek by fish fences above the Polley Lake Weir, while the habitat underwent reconstruction. During the winter of 2014-2015, the creek channel was cleaned up, tailings and debris removed, and a new Hazeltine Creek channel was built and rocked-in.

Fish fences blocking passage from Polley Lake (top left) into upper Hazeltine Creek [2015]
Fish fences blocking passage from Polley Lake (top left) into upper Hazeltine Creek [2015]

In April 2015, the Habitat Remediation Working Group (HRWG*), including the T’exelc First Nation (Williams Lake First Nation) and Xatśūll First Nation (Soda Creek Indian Band) and their consultants, and Mount Polley Mining Corporation (MPMC) representatives and their consultants (Envirowest and Golder), began discussing options for constructing new fish habitat in upper Hazeltine Creek, and requirements MPMC would need to meet in order for fish to be allowed to return to the creek.

*HRWG also includes representatives of the federal Department of Fisheries and Oceans, the provincial Ministry of Environment, and the provincial Ministry of Forest Lands and Natural Resource Operations, both water stewardship and fisheries sections.

Mount Polley employees, consultants, contractors, First Nations and community partners began ecological remediation work on Hazeltine Creek in 2015. By May 2015 the water in Hazeltine was running clear, and the bugs (invertebrates that provide food for fish) were starting to grow in the creek, so it was decided that the installation of new fish habitat could begin and this work started in 2016.

HRWG members looked at historical records to determine what the local conditions were before the spill, and remediation planning was based on that information. The planning was also constrained by the configuration of the constructed rocked-in channel. The group agreed to a field fit approach for the remediation. Conceptual designs were developed by Mount Polley and their consultants, and the plans were reviewed by the HRWG.  

The design approach was to naturalize the rocked-in channel by adding sinuosity (curves and bends), building a sequence of pools, riffles and weirs, and installing boulders, large woody debris and gravel at the bottom of the creek, to provide appropriate spawning and rearing habitat for the fish known to have used upper Hazeltine Creek before the spill, particularly Rainbow Trout, an important species in Polley Lake.

Abundant Rainbow Trout observed upstream of fish fences, looking to transit into Hazeltine Creek from Polley Lake to spawn. [May 2017]
Abundant Rainbow Trout observed upstream of fish fences, looking to transit into Hazeltine Creek from Polley Lake to spawn. [May 2017]

After two years of habitat construction (2016-2017) approximately 2.5 km of spawning and rearing habitat was completed in the upper part of Hazeltine creek from the outlet of Polley Lake to the Gavin Lake Road Bridge. In late 2017, the MPET believed conditions were right to let the fish back into the creek. There was habitat, flowing water, and food, and the water quality met aquatic guidelines.

In December 2017, the HRWG began detailed discussions on the approach to allowing the Rainbow Trout back into Hazeltine Creek. Discussion included requirements for fish monitoring, water quality, sediment quality, habitat quality and quantity, Polley Lake access and egress etc, and the permits and licenses that Mount Polley would have to apply for and comply with from the Ministry of Forests, Lands, Natural Resource Operations and Rural Development Water Stewardship Group.

In March 2018, new fish fences were installed in Hazeltine Creek approximately 2.6 km from the outlet of Polley Lake to prevent fish from going further downstream than the area where habitat reconstruction have been completed. On April 26, 2018, the fish fences at the outlet of Polley Lake to Hazeltine Creek were removed and the Rainbow Trout once again had access to the first 2.6 km of upper Hazeltine Creek.

Note:  the lower part of Hazeltine Creek includes a steep rock canyon that is a natural barrier preventing Quesnel Lake fish from entering middle and upper Hazeltine Creek and Polley Lake. However, in the natural creek system, fish from Polley Lake can be swept down the creek into Quesnel Lake once all the fish habitat reconstruction is completed and fish fences are removed.

In addition to ingress into Hazeltine Creek, the fish also needed to be able to return to Polley Lake. This required that a fishway (ladder) be built for the fish to bypass the Polley Lake Weir water control structure. An engineered fishway was installed by Mount Polley maintenance staff at the Polley Lake weir and the flows are monitored to properly maintain water levels for fish passage.  The fishway was designed so the flow can be adapted to seasonal changes.

Mount Polley fishway ladder
Mount Polley fishway ladder

Fish monitoring was intense in 2018.  MPET worked with Minnow Environmental conducting weekly surveys of the fish populations to track the 2018 spawn and fish activity. The surveys included counting fish at established monitoring stations and pools, and observing how the fish used the creek (i.e. seeking shelter under woody debris or behind boulders). Temperature data and dissolved oxygen levels were also monitored in Hazeltine Creek.

Results of the 2018 Hazeltine Creek fish re-introduction were very impressive. Fish monitors estimated almost 5,000 Rainbow Trout accessed the creek to spawn in spring 2018.  The spawn was successful. A spawning survey in July 2018 observed over 18,600 Rainbow Trout in upper Hazeltine Creek, the majority being from the 2018 spawn.

Spawning rainbow trout in Hazeltine Creek. [late May 2018]
Spawning rainbow trout in Hazeltine Creek. [late May 2018]
Categories
Mining facts

Mining and Mineral Processing at the Mount Polley mine

In the Mount Polley Mine, run-of-mine ore from the open pits and underground is hauled to the crusher.  The crusher has three stages of crushing involving five crushers, twenty conveyors and four sets of screens.  Ore is dumped by the surface mining fleet into the feed pocket of the primary gyratory crusher, and is then crushed in three stages to produce a product at finer than 16 mm for the grinding circuit. Periodically, the crusher also used for the production of aggregates used in tailings construction and other tasks.

The grinding circuit consists of two parallel rod mill/ball mill circuits and a pebble mill circuit. Crusher product is first split between two rod mills where water is added to form slurries.  The rod mill discharge is pumped to the primary hydrocyclones that classify the particles by size.  The larger particles flow to feed the ball mills while the fine particles report to two flash flotation cells. The ball mills are in “closed circuit”, meaning that the discharge is pumped to the classifying units (primary hydrocyclones) and the particles will not pass to the next grinding stage until they are fine enough to feed through the flash flotation cells.  The underflow from the flash flotation cells is pumped to the secondary hydrocyclones, the flash flotation product can report directly to the concentrate circuit or to regrind for further upgrading.

The coarse particles classified by the secondary hydrocyclones reports to three pebble mills for further size reduction. The pebble mills are in “closed circuit” with the secondary hydrocyclones and product that is sized at 65% finer than 200-mesh is fed to the flotation circuit. Pebbles obtained from the triple deck screen in the crusher are used as grinding media in the pebble mills.

The flotation circuit separates the valuable minerals from the rest of the crushed rocks. With the addition of reagents, the valuable minerals, mostly in the form of sulphide minerals chalcopyrite and bornite, are separated by flotation and are collected and upgraded to produce a concentrate. Initial separation is completed in a rougher/scavenger circuit, where the remaining minerals are discarded as tailings (which flow by gravity to the Tailings Storage Facility).  Rougher concentrate is reground in a regrind mill and further upgraded in a cleaner circuit to produce the final concentrate product. Cleaner tailings are recycled to the scavenger circuit.

The concentrate from the flotation circuit is dewatered in two stages: the thickener settles particles and decants water so that the settled particles form a sludge by sedimentation and have a reduced water content of roughly 25%-30%; pressure filtration further reduces water content to approximately 8%. The water removed is utilized as process water. The filtered concentrate is stored in the load-out building and loaded onto 40-tonne trucks for shipping. Tailings materials generated by mill operations are piped via gravity to the TSF.