Green Mining Conference Water Management and the Environment Maria Story, P. Eng. 13 September 2018

Introduction

It became clear to me early in my career: that water quality was COMPLICATED and CONTROVERSIAL but we had to start looking at every project HOLISTICALLY to make the best decisions for the ENVIRONMENT as a WHOLE focussing on one environmental medium could have more negative impacts on other environmental media

Establishing PWQOs & CWQGs PWQO is the concentration of water quality which is protective of all forms of aquatic life and all aspects of the aquatic life cycles during indefinite exposure to the water (MOECC, 1994) CWQGs is a concentration of water to protect all forms of aquatic life and all aspects of the aquatic life cycles, including the most sensitive life stage of the most sensitive species over the long term (CCME,1999)

20 d very severe unfavourable effect 28-d LC50 7-d LOEC 14-d EC20 (growth) 21-d EC16 (reprod) 7-d LC80 14-d EC50 (growth) 20 d very severe unfavourable effect EC50

Case Studies Historic Cobalt/Coleman Mining Camp Unrealistic Effluent Limits Cobalt Constructed Wetland

Historic Cobalt Mining Camp

20 d very severe unfavourable effect 28-d LC50 7-d LOEC 14-d EC20 (growth) 21-d EC16 (reprod) 7-d LC80 14-d EC50 (growth) 20 d very severe unfavourable effect EC50

Unrealistic Effluent Limits

threshold for sub-lethal effects (12 mon) Published Chronic Toxicity Data for Unionized Ammonia Daily Effluent Limit = 0.04 mg/L Monthly Average Effluent Limit = 0.02 mg/L 62-d EC20 LOEC (4 mon) 30-d IC20 survival/growth 7-d IC20 for fry growth threshold for sub-lethal effects (12 mon) gill damage (6 wks) 7-d EC20 reduction develop

Conservatism when Establishing Effluent Limits Lowest Flow in Receiver (7Q20 = 7 d in 7300 d) Maximum Effluent Flows Maximum Effluent Concentrations Low Effluent Limits Over Engineered Resource-Intensive Treatment Systems

Two Tiered Approach Low Effluent Concentration Limits the original 0.02 and 0.04 mg/L protective during low flow conditions no flow monitoring requirements Higher Effluent Concentration Limits higher flow conditions with receiver flow monitoring requirements to ensure a specific mixing ratio and adequate assimilative capacity

Cobalt Constructed Wetland (on Ferland Tailings)

Cobalt Constructed Wetland - Loadings

Cobalt Constructed Wetland - Concentrations

The 7 words to failure are: “We have always Conclusions The 7 words to failure are: “We have always done it this way.” It is time for change.

Acknowledgements Thanks to: Agnico Eagle Mines Limited for sharing data from their surface water sampling program. and The Corporation of the Town of Cobalt for sharing data from their Industrial Sewage Works Constructed Wetland. Maria Story, P.Eng. (SEI President) maria.story@storyenvironmental.com