Land Treatment of Mine Water Presented by: Andre Sobolewski, Microbial Technologies

Proposed Treatment Metals are predicted to be at very low concentrations, so focus is on ammonia Land treatment is proposed Propose to spray mine water onto land (spray irrigation), where plants and soil microbes utilize ammonia –This will effectively fertilize the land

Spray Irrigation – What is it? Spray guns are spaced apart to apply water evenly across treatment area (can be moved around) Water is pumped from PKCA through network of ‘spray guns’ Treatment occurs as water travels through soil Both ammonia and metals will be removed

Spray Irrigation

Spray Irrigation - Characteristics Advantages : –Simple (few parts needed, easy to assemble and easy to get parts) –Flexible (easy to start and can be moved around) –Used worldwide (extensive experience under many conditions) –Inexpensive Disadvantages : –Not yet applied in Arctic

Spray Irrigation Area Proposed spray site located between PKCA and Lake C3 Area is large enough –Calculations show that 5 hectares would be required, there are over 15 hectares available Gently sloping (1-3% slope) High proportion (>70%) of continuous vegetative cover, not boulder fields Organic-rich soil Field trials conducted in 2001 show that the land is suitable for spray irrigation

Potential Impacts - Chloride Concern was expressed about effects of salts - specifically chloride - on plant health Tests were conducted during study on site –Chloride shown to be toxic at 1,000 mg/L –Chloride in PKCA water is expected to be present at a lower concentration –Chloride will not accumulate in soil No environmental impact is expected

Evaluation of potential impacts Chloride – not present at toxic levels Ammonia – Stimulates plant growth Metals in soil – will be monitored Salts in soil – salt concentrations will decrease during the project Permafrost – will be monitored

Monitoring program Monitoring program will be developed to ensure that good quality water is discharged into Lake C3 Metals will be monitored in soil Active layer will be monitored Treatment area will be moved or expanded if: Ammonia concentrations are too high Metals start to accumulate excessively in soils Permafrost begins to deteriorate

Summary Water treatment may be required if ammonia and metals levels are elevated PKCA discharge will be monitored Spray irrigation will be used to remove ammonia and metals from discharge, if necessary A monitoring program is proposed to mitigate potential risks