Water Balance and Water Quality Predictions for the Cariboo Gold Project Filtered Tailings Facility

December 16, 2024

Klohn Crippen Berger Ltd. (KCB) developed an integrated water balance and water quality model (“the model”) in GoldSimfor the provincial Environmental Assessment of the proposed Cariboo Gold Project (“the Project”) at the Quesnel River (QR) Mill site near Quesnel, British Columbia, Canada.

Previous operations at the QR Mill site from 1994 to 2022 processed and stored conventional tailings under a water cover designed for geochemical control in the Tailings Storage Facility (TSF) and Main Zone Pit. For the proposed Project, the existing TSF pond water will be drained down, treated, and discharged. New tailings generated from the Project will be filtered and placed in lifts over the existing TSF tailings. However, the Project’s filtered tailings will be highly sulfidic and potentially acid generating. As a result, proactive water management is required during the Project to achieve environmental discharge criteria.

KCB used the model to assess required water management and treatment, control measures, and facility design for each project phase, including closure. Discharge flow and water quality predictions for the Project footprint and receiving environment were used to support the Project effects assessments for the Environmental Assessment. This process evaluates how the proposed strategies will meet regulatory criteria and provincial guidelines. The Project Environmental Assessment started shortly after the 2018 revision to the British Columbia Environmental Assessment Act. The timing of the assessment provided unique challenges for the owner, regulatory agencies, stakeholders, and consultants navigating the updated Act.

To assess a range of potential conditions, KCB conducted sensitivity scenarios on the control measures, climate conditions, and geochemical conditions. Water treatment, geomembrane covers, and seepage interception were identified as important control measures to meet water quality requirements.

Key takeaways from the application of the model for the Project include the importance of proactive risk management, early consideration of best available technologies, communicating with regulators and other consultants, and planning for closure in a changing climate.

Thuysbaert, J., J. Piccolo-Lawrance , J. Quinn and R. Girard. 2024. “Improving Tailings Deposition: A Drone and Satellite Survey Validation Framework for Enhanced Facility Management,” in Proceedings of the Tailings and Mine Waste Conference, 10-13 November 2024. Colorado, USA.