Sullivan Mine: Water Collection Closure Plan Vs. 10 Yrs Post-Closure Experience Authors: Michelle Unger, Bsc
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Sullivan Mine: Water Collection Closure Plan vs. 10 yrs Post-Closure experience Authors: Michelle Unger, BSc. & Dave van Dieren, P.Eng Introduction Description of Site Reclamation and Seepage Collection Systems Post Closure Projections and Current Experience: - Underground Mine filling, dewatering flows, water quality and metal loading - Mine Area Seepage flows, water quality and metal loading - Tailings Area Seepage flows, water quality and metal loading Summary of Results Sullivan Mine Location Sullivan Mine History and Layout Mine and Mill areas Subsidence Area Mine Site and Lead, Zinc and Silver Waste Dumps Operated 1909 –2001 City of Primarily underground, some open pit Kimberley 150 million tonnes ore Mill Site and Production (tonnes): Tailings Concentrate: 25.8 million Waste rock: 9.8 million Mark Creek Tailings: 122 million Total area of disturbance: 1100 ha Environmental Concerns: Acid Rock Drainage (ARD) Sulphide oxidation: Historic Photo of Pyrrhotite and pyrite No. 1 Shaft Waste Dump Principal Ore: • Galena and sphalerite ARD impacts to surface water and groundwater : • mine workings; • waste dumps; Historic Photo of North and South Waste Dumps adjacent to Mark Creek Environmental Concerns: Acid Rock Drainage (ARD) Sulphide oxidation: Pyrrhotite and pyrite Principal Ore: • Galena and sphalerite ARD impacts to surface water and groundwater: • mine workings; • waste dumps; and • tailings impoundments Historic Photo of Tailings produced by Concentrator Review Reclamation Plan Revised Decommissioning and Closure Plan 2000 Main Objectives: Wildlife habitat ARD collection and treatment for perpetuity Reclamation progressive from 1990 to 2010 Review Reclamation Plan: Mine Site . Source Control: . Rock from the Open Pit Waste Dump was placed in the Open Pit. Waste dumps were capped with till and re-vegetated with grasses and legumes. Seepage collection: . Underground Mine reservoir . No.1 Shaft Waste Dump groundwater collection . Sullivan Creek surface and groundwater collection . Lower Mine Yard groundwater interception wells Mark Creek: Before and After North and South Waste dumps adjacent to Mark Creek Valley Reclaimed Mark Creek Valley Review Reclamation Plan: Mill Site . Source Control – Mill Area . Engineered cover systems placed on waste impoundments . Re-vegetated with grasses and legumes. Seepage Collection . Groundwater interception ditches keyed into bedrock/till surface . Shallow seeps and runoff collected in ditches . Water collected from all collection systems is stored in the ARD Pond, and treated in Teck’s Drainage Water Treatment Plant (DWTP) Tailings Reclamation – Before and After Water Treatment Post Closure DWTP built in 1979 • high density sludge process • operates in the spring (~ 12 weeks) and fall (2 ½ weeks) • Dewater the u/g mine reservoir and ARD Pond in the spring • Completely empty the ARD Pond in the fall Post Closure Projections U/G Mine filling projections • Estimated void space between mine elevations from bottom of mine 2450 ft and max. operating elevation 3650 ft (initial filling) • Operating range of reservoir is from 3550 ft and 3650 ft with a capacity of 625,000 m3 • Allowance of a 50 ft contingency freeboard Post Closure Projections U/G Mine filling projections Water introduced into the mine 2 ways: 1. Surface infiltration from subsidence area 2. Groundwater inflow Infiltration rate 1.4M m3/yr assuming average precipitation Subsidence area Mine FillingGraph Elevation (feet) 2,400 2,500 2,600 2,700 2,800 2,900 3,000 3,100 3,200 3,300 3,400 3,500 3,600 3,700 Jun-02 Sep-02 Dec-02 Mar-03 Jun-03 Sep-03 Sullivan Mine Water Level Sullivan MineWater Dec-03 Mar-04 Jun-04 Sep-04 Dec-04 Mar-05 Jun-05 Sep-05 Dec-05 Mar-06 Jun-06 Sep-06 Dec-06 Mar-07 Predicated Jun-07 Sep-07 Dec-07 Actual Mar-08 Jun-08 Sep-08 Dec-08 Underground Mine Dewatering U/G Mine Dewatering in subsequent years Year Volume m3/yr 2011 667,377 2010 382,312 2009 588,713 2008 627,926 Projected 1,400,000 Original prediction – dewater spring and fall Actual volume – dewater spring only Underground Mine Water Quality Compound Predicted Initial 2011 end Zn mg/l 130 138 24 Fe mg/l 629 1,150 366 SO4 mg/l 11,115 9,030 5,730 Initial water worse than predicted except for SO4 With pumping water quality is better than predicted Underground Mine Water Quality Mine Water Pumped from U/G 3500 Fe 3000 Zn S 2500 2000 1500 Dissolved Metals mg/l 1000 500 0 Mine Area Seepage Collection Mine Area seepage collection – - No. 1 Shaft waste dump - Sullivan Creek - Aquifer pumps in Lower Mine Yard Predicted volume 940,000 m3/yr Mine Area Seepage Collection Mine Area seepage collection – Seepage Volume vs Time - No. 1 Waste Dump 1.40 - Sullivan Creek Mine Seepage 1.20 - Aquifer pumps in LMY Placement of till cover on No. 1 Waste Dump 1.00 Predicted volume 940,000 m3/yr /yr 3 0.80 Actual volume currently 0.60 ~600,000 m3/yr Volume Mm 0.40 Volume: down immediately upon 0.20 closure and decreased as reclamation progressed 0.00 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 No. 1 Shaft Waste Dump No. 1ShaftWaste Mine Area Seepage Collection • Metal Loading: • Metalconcentrations: flushing event except when thereisa generally decreasing volume Zn withdecreasing increasing especially Dissolved metals (mg/L) 1000 2000 3000 4000 5000 6000 7000 8000 0 Sample Date 3/27/1996 6/9/1997 5/20/1999 4/7/2001 Zn-D Fe-D 5/2/2002 Dump Waste No. 1Shaft 8/1/2002 12/2/2002 4/2/2003 7/30/2003 12/1/2003 4/29/2004 9/30/2004 6/29/2005 10/3/2006 2/1/2007 3/30/2007 4/24/2007 5/22/2007 6/19/2007 8/30/2007 1/2/2008 5/2/2008 9/2/2008 1/7/2009 5/1/2009 3/31/2010 5/3/2011 Lower Mine Yard Lower Mine Mine Area Seepage Collection • Groundwater metal • increased Volume South Dump from decreasing Zn and increasing Fe concentrations: times since 1992 by100 on MarkCr. has reduced impacts aquifer pumpswhich with additional 0.01 Concentration mg/L 0.1 10 Note log scale 1 Apr-92 Apr-93 Apr-94 Apr-95 Apr-96 Zinc Concentration in Mark Creek in Mark Zinc Concentration Apr-97 Apr-98 Apr-99 Apr-00 Apr-01 Apr-02 Apr-03 Apr-04 Apr-05 Apr-06 Apr-07 Apr-08 Apr-09 Apr-10 Tailings Area Seepage Collection Predicted volume 340,000 m3/yr avg. precipitation Actual volume average 500,000 m3/yr last 4 years Tailings Area Water Quality Tailings Seepage Water 1800 Fe Zn 1600 S 1400 1200 1000 800 Dissolved Metals mg/l 600 400 200 0 31/12/2001 31/12/2002 31/12/2003 31/12/2004 31/12/2005 31/12/2006 31/12/2007 31/12/2008 31/12/2009 31/12/2010 Summary Predictions and Actuals Actual Projected Flow (m3/yr) (m3/yr) • Closure 2001 U/G 1,400,000 600,000 • Post reclamation conditions since Mine 940,000 600,000 2007 (3 years of vegetation growth) Tailings 360,000 500,000 • Volumes are approx. 60% less Total 2,700,000 1,700,000 than predicted (primarily u/g) • Water quality better than predicted, the lime consumption Lime consumption is much lower than predicted Projected 6,025 t/yr Average 2,157 t/yr (2008 – 2011) Summary Volume trends Seepage Volume vs Time 2.5 • Mine area seepage Mine Dewatering decrease since Mine Area Seepage reclamation of No. 1 Waste 2 Tailings Seepage Dump Total 1.5 • Tailings area seepage 1 slightly lower than pre Volume Mm3/yr reclamation, too early to 0.5 see a significant difference 0 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 • Total seepage volume no significant trend Summary Metal loading Metal Loading vs Time 1200 • U/G - Significant decreasing Mine Dewatering 1000 trend, expect to level off Mine Area Seepage Tailing Seepage 800 • Mine area seepage – Total decreasing trend primarily due 600 to reclamation of No. 1 Waste Dump t/yr Metal Loading 400 • Tailings area seepage – no 200 significant trend 0 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 • Total loading – no trend at this point Questions?? Elk on Reclaimed Pond •28.