Watershed Management

Protecting downstream water quality is a priority for Pretivm, and is a key interest for our Indigenous partners and other stakeholders. As a result, water management and stewardship is essential in the planning and execution of all our activities at the Brucejack Mine, so that we can preserve natural water quality and flow volumes in the surrounding environment. As described in Effluent & Waste Management, we utilize the natural landscape in our mine design to eliminate the need for a man-made tailings impoundment and dam, and we capture, treat, and test site contact water before discharging it to the downstream environment. Unlike many gold mines, we do not use cyanide in the gold extraction process, so we avoid the hazards associated with cyanide management.  

Water is a shared resource, and we engage with authorities in BC, Alaska, and Indigenous governments on topics related to water management, permits, and potential downstream water impacts. We also report to Indigenous groups about on our compliance with effluent discharge permits. 

Integrated Water Management

Pretivm uses an integrated approach to watershed management, in both the design and operation of the Brucejack Mine. Our high-elevation mine site receives a high volume of rain and snow throughout the year, with an average snow depth of nearly four metres in the winter. All water that comes into contact with excavated bedrock material must be contained and treated, so we have created channels around the site to divert meltwater and surface runoff away from the mine site, reducing the volume of contact water. We collect and contain the runoff water that does contact excavated bedrock, and treat it before discharging to the Waste Rock and Tailings Storage Facility with eventual outflow back to the receiving environment.

As part of our environmental management system, the Water Management Plan for the Brucejack Mine is supported by six additional EMPs1  related to different aspects of water management and various departments within our operation are involved in the management. The VP, Environment and Regulatory Affairs oversees the environmental team responsible for maintaining and monitoring water quality at the Mine, in collaboration with the Mine General Manager.

1EMPs supporting water management include the Aquatic Effects Monitoring Plan, Metal Leaching and Acid Rock Drainage Management Plan, Spill Response Plan, Tailings and Subaqueous Waste Rock Deposition Management Plan, Nitrogen Management Plan, Chromium Management Plan, and the overall Water Management Plan.

Data Highlights


17
surface water monitoring stations
2
snow monitoring stations

36
groundwater monitoring wells
3
weather monitoring stations

Water Use and Discharge

Water Withdrawal & Re-Use

The Brucejack Mine is located in a region of high precipitation and little development, and the downstream receiving environment is not considered to be water stressed.2 Nonetheless, Pretivm has designed the Brucejack Mine to limit the use of freshwater and minimize effects on surrounding water bodies. The lifecycle of water at the Brucejack Mine includes water collection and withdrawal, re-use/recycling, treatment, and discharge. Water that comes into contact with our site is collected and recycled or re-used where possible, and excess water that is not reused is treated before discharge to the Waste Rock and Tailings Storage Facility, before ultimately returning to the natural environment. 

Groundwater wells supply our camps with potable water. To provide water for the mill and underground mine processes, we capture groundwater seeping into the underground mine, collect surface runoff from rainfall and snowmelt that has contacted the mine site surface, and recycle process water within the mill. Consistent with prior years, we recirculated two-thirds of all water used in the mill and mining process in 2020. If additional process water is required, we withdraw supplemental water from the Waste Rock and Tailings Storage Facility.

2As defined by the World Resources Institute, water stress is represented by the ratio of total water withdrawals to total renewable supply in a given area.

Water Treatment & Discharge

Water from the contact water collection system, mill and the underground mine is treated at our on-site industrial water treatment plant which removes metals and impurities. Treated water is recirculated in the mill or discharged to the Waste Rock and Tailings Storage Facility. Our on-site sewage treatment plant treats wastewater from the camp, and the potable water treatment facility treats water in preparation for human consumption.

We ultimately discharge treated water to the Waste Rock and Tailings Storage Facility. The outflow from the Waste Rock and Tailings Storage Facility is the single point of effluent discharge to the downstream receiving environment. Federal and provincial legislation regulates effluent discharge at the Mine, stipulating requirements for several water quality parameters including turbidity and dissolved metals. We monitor effluent and compare this to applicable water quality standards and permitted discharge criteria and report this information to provincial and federal regulators.

The water quality of the Waste Rock and Tailings Storage Facility is the key indicator for success of Pretivm’s watershed management approach. Outflow from the Waste Rock and Tailings Storage Facility forms the majority of flow in Brucejack Creek. Brucejack Creek is not fish bearing due to a natural fish barrier 20 kilometres downstream of the mine site, which prevents fish from traveling further upstream.

In addition to the treated wastewater from the mine site, the Waste Rock and Tailings Storage Facility also receives deposits of tailings and waste rock, as explained in Effluent & Waste Management. We are committed to managing the water quality of outflow from the Waste Rock and Tailings Storage Facility to avoid negative impacts on water quality further downstream and our approach has proven a success.

Our overall water consumption at the Brucejack Mine amounted to 14,346 cubic metres in 2020, compared to 108,929 cubic metres in 2019, and 129,288 cubic metres in 2018.

Data Highlights

1,075,586 m3
of water recirculated in the mill and mining process
66%
of water is recirculated in the mill and mining process
Water Withdrawal by Source (Cubic Metres)
Target
1,500,000

1,250,000

1,000,000

750,000

500,000

250,000

0

1,015,667

528,511

461,461

25,695

 

1,191,582

651,305

511,746

28,531

 

1,363,940

757,272

574,348

32,320

 
201820192020
Groundwater (potable water from well)
Groundwater (captured from underground mine)
Surface water
Water Discharged (Cubic Metres)
Target
1,500,000
1,250,000
1,000,000
750,000
500,000
250,000
0

781,294

280,125

501,169

 

971,775

211,516

760,259

 

1,138,484

443,205

695,279

 
201820192020
Volume discharged with tailings
Treated volume discharged

Monitoring Water Quality

As outlined in our approach to Environmental Management, Pretivm’s commitment to water management is achieved through a robust program of inspections, audits, environmental monitoring, and continual improvement. Weekly monitoring of water quality at the Waste Rock and Tailings Storage Facility outflow verifies whether our management measures are effective. We compare the monitoring results to predictions made by water quality models, and input the results back into the model to refine future predictions. In 2020, we updated and recalibrated our water quality models based on actual data gathered over the last few years, to further improve their accuracy. Additionally, we commissioned a third-party review of our management practices related to the Waste Rock and Tailings Storage Facility with resulting recommendations being implemented in 2021.

At the Brucejack Mine, our water quality monitoring program encompasses facilities and natural water bodies in and around the mine site. At the site, we monitor the quality of mill process water as well as effluent from the on-site sewage treatment plant and industrial water treatment plant. Water quality of the outflow from the Waste Rock and Tailings Storage Facility is a key indicator, and we monitor water quality within the facility itself, at the outlet to Brucejack Creek, and in the downstream receiving environment. We monitor a comprehensive suite of water quality parameters including general water chemistry and metal concentrations. Some of the key parameters we track are total suspended solids, pH, conductivity, temperature, and metals such as chromium, copper, silver, and iron. Average levels of these parameters have consistently been well below permitted discharge criteria.

Our goal is to meet or exceed regulatory requirements for environmental performance. This is evident throughout our operation and is particularly relevant in our efforts to protect water. We are proud to report no water quality incidents of non-compliance in 2020. In addition to regulatory compliance, we have established internal triggers for water quality that prompt management action. These internal triggers are lower than the regulatory limits and support our role as a responsible environmental steward.

Annual Averages at Waste Rock & Tailings Storage Facility Outflow3

Parameter 2018 2019 2020 Permitted Discharge Criteria4
pH 7.87 7.90 7.86 6.5–8.5
TSS (Total Suspended Solids) 2.53 4.61 4.38

15 mg/L (monthly average)

30 mg/L (maximum)

N-NH3 (Ammonia) 0.05386 0.0351 0.0707 4.0 mg/L as N
N-NO3 (Nitrate) 4.62 6.58 7.47 11.5 mg/L as N
N-NO2 (Nitrite) 0.0132 0.0151 0.0121 0.240 mg/L as N
T-Sb (Antimony) 0.00571 0.00780 0.00890 0.028 mg/L
T-As (Arsenic) 0.00496 0.00674 0.00695 0.01 mg/L
T-Fe (Iron) 0.0305 0.0349 0.0496 1.7 mg/L
T-Ag (Silver) 0.0000173 0.0000103 0.0000117 0.00046 mg/L
 Note: Any values below detection were measured as the detection limit.
3Water quality measured at discharge compliance point BJ 3.10.
4As of December 31, 2020.

Highlight Story

Claiming Her Place in the Mining Industry

Growing up just outside of Jasper National Park, our Director of Environmental and Regulatory Affairs Sylvia Van Zalingen has always had an affinity for the environment and being outdoors. While studying Wildlife Biology, she was introduced to mine reclamation and decided to pursue a master’s degree in Land Reclamation at Montana State University. 

Sylvia has experience working in the mining industry at operating mines as a consultant, and as a Mines Inspector. “In my early work years, even as a Mines Inspector, there were a lot of sexist remarks and obvious assumptions by some that I couldn’t possibly know much of anything about mining,” she says, “but I never let it slow me down. The industry has made huge strides to encourage female participation during my 30 plus year career and I look forward to continued improvements.”

She ended up moving to Smithers after hiking in the mountains in the area and falling in love with northern BC. Due to her work as a mines inspector, she had the opportunity to experience many remote exploration and mining sites including Brucejack in the 90s. “Brucejack has been my most in depth path of being involved from planning through to operations,” she says. “I enjoy the exceptional people on our team. So many super capable and great human beings.” She wants to encourage everyone that has an interest in mining and the environmental field: “Do what interests you and makes you proud of your work and contributions. There are so many more opportunities for young people in mining and environmental sciences compared to when I started working.” 

 
Our Values

RESPECTCAREINTEGRITY