Potassium Effluent Quality Criteria Water Licence Amendment Application Public Hearing, February 8, 2018 Dominion Diamond Ekati ULC
SECTION TITLE Presentation Overview • Water Licence Amendment Request • Environmental Protection at the Ekati Diamond mine • Intervention Recommendations and Responses • Summary 1
SECTION TITLE Water Licence Amendment Application • Dominion is requesting that potassium EQC at the Ekati Diamond Mine be aligned with the approved Site Specific Water Quality Objectives (SSWQO) • Maximum Average EQC = 64 mg/L • Maximum Grab EQC = 103 mg/L • SSWQO represents our best understanding of environmental risk associated with potassium toxicity • Reflects current state of science including recently published and site-specific data • Consistent with the WLWB’s Water and Effluent Quality Management Policy • Direct link between receiving environment guidelines/objectives and EQC • Facilitates clear and consistent interpretation and application of Licence requirements • Consistent with process for establishing EQC at the Ekati Diamond Mine • Provides consistency between Water Licence and the Potassium Response Plan • Current EQC is not reasonably achievable 2
SECTION TITLE Environmental Protection at the Ekati Diamond Mine • Dominion has rapidly identified and responded to concerns over potassium at the Ekati Diamond Mine and is committed to ongoing adaptive management • Adaptive management of environmental change at the Ekati Diamond Mine is governed by many layers of environmental protection aimed at ensuring Significance Thresholds are not reached • A level of environmental change in any monitored variable which, if reached, would result in a significant adverse effect Effluent Quality Criteria AEMP Benchmark Minewater Receiving Environment Management Facilities (e.g., Leslie Lake) (e.g., LLCF) Site-specific Water Quality Objective (SSWQO) 3
SECTION TITLE Environmental Protection at the Ekati Diamond Mine Aquatic Effects Monitoring Program Wildlife and Humans • A comprehensive, early-warning monitoring program designed to detect change in aquatic ecosystems Fish Aquatic Response Framework • An early-warning system with defined action levels that are initiated within Zooplankton Benthos an adequate timeframe to prevent the occurrence of significant adverse environmental impacts Phytoplankton Sediment Quality Water Quality TITLE 4
SECTION TITLE Environmental Protection at the Ekati Diamond Mine Significance Thresholds Levels of environmental change which, if reached, would results in significant adverse effects Potassium Concentration AEMP Benchmark = SSWQO = 64 mg/L High If exceeded could result in localized sublethal effects Medium Action Levels Low Mine Operations 5
SECTION TITLE Recommendations and Responses • ECCC Recommendation 1,2 and IEMA Recommendation 1 • Rationale on how exceedance of the SSWQO in the aquatic receiving environment are protective of the aquatic environment should be provided. • If higher concentrations in the receiving environment are demonstrated to be protective, an updated potassium SSWQO should be provided. 6
SECTION TITLE Recommendations and Responses • Dominion Response • EQC established using ‘Use - Protection Approach’ consistent with WLWB Water and Effluent Management Policy • Best protection of the receiving environment is through the integration of several site-specific protection measures • EQC, AEMP, ARF • Action levels defined in the ARF allow management actions to be initiated within an adequate timeframe to prevent reaching a significance threshold 7
SECTION TITLE Recommendations and Responses • Dominion Response • Exceedance of SSWQO does not necessarily imply that aquatic biota will be adversely affected • SSWQO is conservative, and scientifically defensible (developed with the most recent best available data using CCME guidance) • A potassium concentration at which a sublethal effect would be expected to the most sensitive species would exceed 100 mg/L • Modelling results indicate potential minor short-duration, under-ice exceedances in Leslie and Moose Lakes — small natural catchment area • No update to the SSWQO is required at this time • The aquatic receiving environment has been shown to be resilient to changes in water quality • e.g., Aquatic Effect Synthesis results 8
SECTION TITLE Recommendations and Responses • GNWT Recommendation 1,2,3 • The GNWT recommends that a 42 ‐ day toxicity test be undertaken using Hyalella azteca to evaluate survival, growth, and reproductive endpoints using site water spiked with potassium concentrations at minimum 64 mg/L, 80 mg/L and 100 mg/L to evaluate the response of this sensitive species. • The GNWT recommends that a 30 ‐ day early life stage test be conducted on fathead minnows using site water spiked with potassium concentrations at minimum 64 mg/L, 80 mg/L and 100 mg/L to evaluate hatching success, survival, growth, biomass, and gross morphological alterations. • The GNWT recommends that toxicity testing be conducted on a freshwater bivalve using site water spiked with potassium concentrations at minimum 64 mg/L, 80 mg/L and 100 mg/L. 9
SECTION TITLE Recommendations and Responses • Dominion Response • The toxicity tests completed for the development of the long- term SSWQO are considered long-term duration tests (CCME 2007) • The additional toxicological tests proposed by GNWT-ENR present technical and administrative challenges • Additional reproductive end-point not warranted • Fingernail clams are not commonly used species in laboratory test — no standardized test methods • Minimum of six months to complete additional testing • Additional toxicity tests would cause unnecessary delay 10
SECTION TITLE Recommendations and Responses • GNWT Recommendation 4 • Given that potassium concentrations are not trending towards the higher EQC at the KPSF and Desperation Pond and there are uncertainties associated with the application of the Koala watershed SSQWO for potassium in these areas, GNWT recommends that the potassium EQC of 64 mg/L not be applied for these areas. Should there be an apparent operational need in the future, and technical uncertainties be resolved, the GNWT would support this matter being reconsidered by the Board. 11
SECTION TITLE Recommendations and Responses • Dominion Response • Site-wide recommendation for the EQC consistent with WLWB decision on the revision of the SSWQO to 64 mg/L • Reflects the current state of science for potassium toxicity • The SSWQO was derived solely on potassium toxicity data following CCME methods • No exposure and toxicity modifying factors have been definitively defined for potassium 12
SECTION TITLE Recommendations and Responses • IEMA Recommendation 2 • Dominion Diamond should clarify whether water treatment is a feasible alternative to reduce potassium concentrations in water discharged at SNP stations 1616-30, 1616-43 and 1616-47 13
SECTION TITLE Recommendations and Responses • Dominion Response • Water treatment options (reverse-osmosis and ion exchange) have high costs and their own environmental concerns • Problematic by-product (brine) management • High fuel consumption and associated greenhouse gas emissions • Significant additional capital and operating costs • Discharge that is environmentally protective can occur without treatment • Amending the EQC to 64 mg/L would provide greater operational flexibility to manage water, while the AEMP and ARF will ensure actions continue to be taken to maintain environmental protection 14
SECTION TITLE Summary • Short- and long-term SSWQO are protective of the receiving environment at the Ekati Diamond Mine • Updated and revised SSWQO have been extensively reviewed • Long-term SSWQO is already in use at the Ekati Diamond Mine • Current potassium EQC of 41 mg/L is not reasonably achievable • Alignment between EQC and SSWQO of 64 mg/L is: • appropriate and protective of the receiving environment; and • consistent with WLWB policy and with the established process of setting EQC at the Ekati Diamond Mine 15
SECTION TITLE Thank You Dominion Diamond Ekati ULC
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