Brucejack Project Feasibility Study

BGC completed underground rock mechanics assessments to support the Preliminary Economic Assessment (PEA), Feasibility Study (FS), and Permitting for Pretium Resources Inc. Brucejack Project near Stewart, B.C.

Geotechnical assessments completed to support the underground mine design included:

• Supported and unsupported stope hydraulic radii
• Rib, sill, and crown pillars
• Ground support
• Portal stability
• Ramp stability
• Underground crusher chamber stability
• Recommendations for mining through the Brucejack fault zone

Designs were based on site investigations from 2010 through 2012, exploration data, lab testing, and a compilation of work from external consultants. Analytical, empirical and numerical modelling methods were used to estimate achievable spans and support requirements for the proposed mine openings. Challenges included interpreting the thickness, orientation, and rock mass characteristics of the Brucejack fault zone to design stopes and developments in fault disturbed rock.

The mine was successfully permitted and commenced production in 2017. Between 2017 and 2020, BGC completed annual geotechnical site visits, reviewed and updated the site’s Ground Control Management Plan, and provided as-needed geotechnical support to the mine’s operations team.