Greenstone Gold Mines GP Inc. - Environmental Compliance Approval (sewage)

Greenstone Gold Mine (GGM) is proposing to amend the Environmental Compliance Approval (ECA) No. 0735-C9PMD6 to facilitate the operations phase of a new open pit gold mine located in northwestern Ontario, approximately 275 kilometres northeast of Thunder Bay, in the Municipality of Greenstone, Ward of Geraldton.

GGM is proposing to amend the ECA to include the following in the approval for mine operations:

• Inclusion in the ECA description of works the on-land portion of the effluent pipeline.
• Construction and operation of emergency pond and ditch associated with the reclaim lines and tailings, discharge line, and addition of emergency pond and ditch in the description of the ECA works.
• Construction and operation of a tailings reclaim line extending from the Tailings Management Facility (TMF) to the processing plant, and addition of a tailings reclaim line in the description of the ECA works.
• Construction and operation of a tailings discharge line extending form the processing plant to the TMF, and the addition of a tailings discharge line in the description of the ECA works.
• Construction and operation of TMF seepage collection pond T2, with recirculation of seepage to the TMF, and addition of the description of the proposed works to the ECA.
• Historical tailings water management during relocation of historical tailings, which required direction of water via gravity drainage and pumping to the open pit, and the to the full-scale Effluent Treatment Plant (ETP).
• A proposed oil water separator and water treatment system associated with the truck wash bay that will clean and recirculate water for the same use.
• Consolidation of the sewage works approved under ECA No. 7554-D4EPL5.
• Modify the Works Description to reflect the full height of the TMF dams.
• Modify the Works Description to reflect the planned mill throughput of 10,900,000 tonnes per year.

Phosphorus has been historically elevated in Kenogamisis Lake and above the Provincial Water Quality Objectives for the protection of aquatic life in certain locations in the lake. GGM has implemented the best available phosphorus treatment technology, but the proposal will increase the load of phosphorus to Kenogamisis Lake as a result of the project discharges. To address concerns with this proposal, GGM will implement an enhanced monitoring program to evaluate the risk of their discharges and to assess potential changes to phosphorus concentrations in Kenogamisis Lake.

GGM will report to the Ministry of the Environment, Conservation and Parks and sample any cyanobacteria (blue-green algae) blooms observed during routine sampling events throughout Kenogamisis Lake to ensure risks due to these events are communicated to users within the broader watershed.