Sulfide mining in Upper Great Lakes

May 4, 2018 | Author: Anonymous | Category: Technology
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1. A New Environmental Threat in theUpper Great Lakes Region:Sulfide MiningPrepared for: National Wildlife FederationPrepared by:Ann Maest, PhDRichard StreeterStratus ConsultingBoulder, COandBob Prucha, PhD, PEIntegrated Hydro SystemsBoulder, COSTRATUS CONSULTING 19 March 2011 2. Geographic Extent of ProposedMining Copper and other base metal deposits are wide-spread in the upper Great Lakes region –associated with midcontinental rift Deposits are concentrated in Upper Peninsula ofMichigan and Minnesota near Duluth (copper,nickel, platinum group metals, gold, uranium) Prospects are located on and near National Forestand tribal lands Some deposits and proposed processing plants arewithin a few kilometers of Lake Superior or LakeMichigan Increase in exploration associated with increasedworldwide demand (led by China and India) andincreasing metal pricesSTRATUS CONSULTING 3. Midcontinent Rift Rocks in the midcontinent rift are an importantsource of copper and silver.Source:STRATUS CONSULTING http://www.geo.lsa.umich.edu/teaching/Bedrock%20v6.pdf 4. Overview of Potential Mines andAssociated FacilitiesSTRATUS CONSULTINGSee references for project locations and commodities. 5. Potential Environmental Impacts Mine development will impact wetlands, surfacewater, groundwater, landscapes, aquatic andterrestrial biota, and human health Potential effects include – Destruction of wetlands and terrestrial habitatfrom mine facilities – Draining of wetlands and lowering ofgroundwater levels from dewatering – Metal and acid contamination of streams,wetlands, stream sediment, aquaticinvertebrates, fish, groundwater, drinking waterwells, and surface runoff – Mine subsidence (collapse affects land surface,waterways) Regulatory agencies not adequately staffed toreview proposals or manage new miningSTRATUS CONSULTING 6. Screening methods used to identifypotential environmental impacts from theproposed mines and projects Used largely industry sources for location of mineprojects; assigned confidence levels for locations Estimated amount of groundwater, wetlands, streams,and disturbed areas potentially affected by proposedprojects – see reference section for details Measured amount of historically disturbed area at theEagle and Northmet sites Calculated amounts of potentially disturbed watersand lands are likely underestimates of actual mine-related disturbance and effects (e.g., does not includegroundwater)STRATUS CONSULTING 7. Minnesota Projects: PotentiallyAffected Surface Water ResourcesSTRATUS CONSULTING 8. Eagle and Eagle East Projects: PotentiallyAffected Surface Water ResourcesSTRATUS CONSULTING 9. Humboldt Mill: Historic Tailings Areasand Potentially Affected WaterwaysPotentialNote: Former pit will be filled withtailings and impact streams to northSTRATUS CONSULTING 10. Extent of Potential Wetland and Stream Impacts Extent of potentially impacted wetlandsat least 7,320 acres – Includes wetlands within ¼ mile of Eagle Haul Road and areas within 1-mile radius of project area (predicted size of cone of depression for Eagle Project) Extent of potentially impacted streamsat least 441 miles – From project areas downstream to dam or large lake Likely underestimates impactsSTRATUS CONSULTING 11. Potential Groundwater Impacts Many communities rely on groundwater for drinkingwater Mine dewatering operations could decreaseavailability of groundwater for many uses – Eagle will pump 113 million gallons/yr – NorthMet will pump up to 599 million gallons/yr Development of mines could contaminategroundwater during and after mining and adverselyaffect human health Following slides show alluvial aquifers (bedrockaquifers are also at risk of contamination) andknown well locationsSTRATUS CONSULTING 12. Known Wells and Alluvial Aquifers in UpperPeninsula of MI and Northeastern Wisconsin See references for sources of aquifer and well locations. USGS atlas doesSTRATUS CONSULTING not include smaller continuous aquifer systems. 13. Known Wells and Alluvial Aquifers inNorthern MinnesotaSTRATUS CONSULTINGSee slide 4 (overview map) for regional location. 14. Potentially Impacted Wells and Groundwater Pumping  Wells in vicinity of projects in Michigan and Minnesota on previous maps: 429 to 652 wells– Lower number is for wells within 1-mile radius, higherfor 2-mile radius– Only includes existing domestic wells in vicinity ofprojects with high confidence of location• For example, there are 29 domestic wells betweenNorthMet site and Embarrass River to the north– Does not include wells in Wisconsin – no statedatabaseSTRATUS CONSULTING 15. Loss of Groundwater Use from Dewatering Operations  Groundwater pumping– Eagle Project estimates: • Estimated pumping ranges from 75 to 215 gallons/minute over nine years of operation– NorthMet Project estimates: • Dewatering will lower flows in Partridge River, drawdown levels in Whitewater Reservoir, and lower groundwater levels • Estimated pumping ranges from 200 to 1,150 gallons/minute over 20 years of operation Sources: Foth & Van Dyke and Associates.STRATUS CONSULTING 2006a; NorthMet DEIS, 2009. 16. Loss of Groundwater Use from Dewatering Operations (cont.)– Water pumped at a subset of the projects in thisstudy would supply between 76,000 to 407,000people per year with domestic water• See methods file – used mine-estimateddewatering rates for Eagle and Northmet– Using 2009 census estimates, the projects woulduse more water annually than Kalamazoo,Michigan (73,000 people) on the low end andMinneapolis (385,000 people) on the high end– Estimates of water use are probably low becausethey do not include likely expansion of operationsor inaccuracies on the upper bound of water useSTRATUS CONSULTING 17. Contaminants of Concern Most base metal sulfide mines have similar contaminants ofconcern – Metals: arsenic, cadmium, copper, lead, nickel, zinc – Non-metals: sulfate (from acid drainage), nitrate andammonia (from blasting agents used to excavate mine),cyanide (from flotation operations) – Acid: acid drainage (from mined materials), low pH Metals do not degrade to less toxic compounds and aretoxic to aquatic life at low concentrations Mineral deposits and surrounding rock in Upper Great Lakesarea are predicted to create acid drainage and leach highconcentrations of nickel and copper (see following slides forEagle Project, MI)STRATUS CONSULTING 18. Health Impacts from Mine-relatedContaminants Liver or kidney damage: copper, cadmium, lead Learning impairment in children: lead Blue baby syndrome: nitrate Known or suspected carcinogen: arsenic Nerve damage/thyroid problems: cyanide Toxic to fish and aquatic biota at low concentrations:cadmium, copper, lead, zinc, ammonia Impacts wild rice: sulfate Sources:US EPA, 2011.STRATUS CONSULTING 19. Eagle Project, MI: Sulfate, pH, and nickelvalues in leachate from semi-massive ore unit60010.00500 SO4 8.00pH400SO 4 (mg/l)6.00pH300acidic4.002002.001000 0.00010 2030 4050 6070 0 10 2030 4050 60 70 Weeks Weeks120More acidic (lower pH) than acceptable range100Ni (6.5-8.5) for USUp to almost 2.5 80 drinking waterNi (mg/l)times higher than60MI water quality 40 Up to 1,200 timesstandard (250 mg/l) 20higher than MI waterquality standard0(0.1 mg/l)0102030 40 5060 70WeeksSTRATUS CONSULTINGData source: Geochimica, 2004, Phase I column 4 (12.85%S) . 20. Eagle Project, MI: Sulfate, pH, and copper values in leachate from surrounding rock 500 10.00 SO4 pH 4008.00SO4 (mg/l) 3006.00pH acidic 2004.00 1002.00 00.00 0 10 20 3040 50 0 10 203040 50 Weeks Weeks14.012.0Cu10.0Cu (mg/l) 8.0 6.0 4.0Up to over nine 2.0times higher than 0.0MI water quality 0 1020 304050standard (1.4 mg/l) Weeks STRATUS CONSULTINGData Source: Geochimica, 2004, Siltstone, Phase II column 4 (1.39%S). 21. Movement of Contaminants Contaminants move away from mine togroundwater and surface water Groundwater feeds wetlands and streams –decreasing groundwater levels and qualitycan dry up surface waters Metals remain in environment for millennia Metals move from water to sediment toaquatic bugs to fish to piscivorousmammals and birdsSTRATUS CONSULTING 22. Contaminants in the Environment Contaminants movedownstream with thewater and sediment,exposing aquatic biota979 Contaminants can betransferred back andforth between shallowgroundwater and streamsSTRATUS CONSULTING969 23. Impacts from Similar Mines  Mines with high potential to generate acid and leach contaminants – and in close proximity to water resources – have the most adverse environmental effects of all hardrock mines (Kuipers and Maest, 2006)– 85% of these mines exceeded surface water quality standards due to mining releases  Proposed mines in the upper Great Lakes have these same inherent characteristics that lead to contamination regardless of commodity and mining method  Water quality standards are exceeded even though permit limits are in place and permit applications stated standards would not be exceededSTRATUS CONSULTING 24. Impacts from Similar Mines (cont.) Known water quality effects from modernsulfide mines near water resources areshown in the following table Other effects include fish kills andreproductive and behavioral effects,draining and destruction of wetlands,lowering of shallow groundwater levels,depletion of stream and spring flowsSTRATUS CONSULTING 25. Impacts from Modern Sulfide Mines inWet Climates Mine Name,OwnershipCommodityOperation TypeWater Quality ImpactsState Groundwater exceedences of manganese, pH,Flambeau sulfate, dissolved solids from pit backfill; (Ladysmith), WIKennecottCopper, gold, silver Open pit, flotationexceedences of copper in stream on site. Hecla Mining Silver, lead, zinc,Surface water contaminated with acidity, sulfate,Greens Creek, AKCompanygold Underground, flotation zinc from tailings/waste rock Springs contaminated with sulfate, copper, zinc, Black Pine, MTASARCOCopper, gold, silver Underground, flotation cadmium, acid drainage from waste rock dump. Placer Dome, Inc.Groundwater contaminated with cyanide andGolden Sunlight, (now Barrick Underground and opencopper from tailings; acid drainage in waste rockMT Gold) Gold pit, vat leachand open pit.Groundwater contaminated with nitrate, Stillwater Mining Platinum group chromium, sulfate, cadmium, zinc from adit Stillwater, MT Company metals Underground, flotation drainage; increased nitrate in surface water.Groundwater/surface water Beal Mountain, increases/exceedences of nitrate, cyanide, sulfate MTPegasus Gold Co.Gold, silver Open pit, heap leach from heap leach and waste rock Open pit, heap and vat Groundwater and surface water contaminated withGrouse Creek, ID Hecla Mining CompanyGold, silverleachcyanide from tailings leakage Surface water contaminated with cadmium,Thompson Creek, Cyprus/Thompsoncopper, lead, sulfate, zinc from tailings and waste ID Creek Mining Co.Molybdenum Open pit, flotation rock seepage; acid drainage in wastes and pitZortman andGroundwater and surface water contaminated with Landusky, MT Pegasus Gold Co. Gold, silver Open pit, heap leach metals, acidity, nitrate, and cyanide 26. Similar Mining Districts Sudbury, Ontario, Canada– Rich copper, nickel, platinum group metal (PGM) sulfidedeposits: 8th richest mining district in world– Formed by meteor impact, but also has massive sulfidedeposits like the Eagle Project in Michigan (acid generators)– Extensive and severe soil and vegetation contaminationfrom smelting; groundwater contamination from acid-generating mine wastes Duluth, Minnesota, USA– Duluth deposit has produced low-pH drainage (as low as4.5 to 6.4) and high metal concentrations (e.g., up to 22mg/L copper Following slides show many mines and prospects inSudbury – there are similar geology, size, andcommodities in Baraga and could be similar impacts See attachment: Comparison to other base metalultramafic depositsSTRATUS CONSULTING 27. Sudbury District, Canada: >200Nickel-Copper-PGE DepositsSTRATUS CONSULTINGSource: Ames and Farrow, 2007 28. Baraga Basin Geology – SimilarStructure and Commodities to Sudbury Source: Prime Meridian Resources.STRATUS CONSULTING http://www.primemeridianres.com/i/maps/baraga/baraga-01.jpg 29. Historical Mining Impacts in theUpper Great Lakes Have Not BeenCleaned Up Historic iron mining destroyed landscapes –less impact to water quality because mineswere generally not acid producers Impacts to land have not been remediated New mining will destroy landscapes andadversely affect groundwater and surfacewater quality and quantity Need to clean up old contamination beforenew mining beginsSTRATUS CONSULTING 30. Ongoing Mining Impacts: nearPalmer, Upper Peninsula, MichiganSTRATUS CONSULTING 31. Historic Mining Impacts:Duluth ComplexSTRATUS CONSULTING 32. Historic Copper and Iron Mining DistrictsSources: mining areas = http://www.mg.mtu.edu/shaft0.htm.STRATUS CONSULTING Surficial geology = USGS  http://tin.er.usgs.gov/geology/state/state.php?state=MI 33. Specific Projects Eagle Project in Michigan and NorthMet inMinnesota are in permitting stage or havealready been permitted – Expected land disturbance = 144 acres at Eagle Project and 6,430 acres at NorthMet Others range from initial to full-scale exploration Specific information on mine plans and potentialimpacts for the Eagle Project and NorthMetProject are included in the following slidesSTRATUS CONSULTING 34. Eagle Project, Michigan Project has been approved by State of Michigan – Project is in native ceded territory – Main river (Salmon Trout) flows into Lake Superior Copper, nickel in massive sulfide deposit with highacid drainage and contaminant leaching potential Potential for contamination of groundwater andsurface water, loss of water from wetlands, loss ofwater from Salmon Trout RiverSTRATUS CONSULTING 35. Eagle Project, Michigan (cont.) Underground mine; transport along haul roadfor flotation processing; discharge of treatedwater at ground surface – Existing water and soil contamination atHumboldt Mill site (tailings area) has notbeen addressed – Close to residential well, and groundwater iscontaminated with arsenic, manganese,vanadium Water and contaminant flow during and aftermining are shown in the following slidesSTRATUS CONSULTING 36. Eagle Project: Flows during Mining Mine immediately beneath Salmon Trout River; flow inriver could decrease from mine dewatering operations Discharge from Treated Water Infiltration System(TWIS) will not meet surface water standards Extensive groundwater impacts – contaminants willlikely travel along extensive permeable faultsSTRATUS CONSULTING 37. Eagle Project: Flows after Mining Contaminated water from mine could flow todowngradient groundwater, Salmon Trout River,and Lake Superior Contaminants would include metals and acid frommining and brine from deep groundwaterencountered during miningSTRATUS CONSULTING 38. NorthMet Project, Minnesota First non-ferrous (sulfide) mine in MesabiRange: Copper, nickel, platinum groupmetals Three open pits, large disturbed area(>6,000 acres) Located within Superior National Forest,land ceded by Indian tribes where theyexercise their treaty rightsSTRATUS CONSULTING 39. NorthMet Project, Minnesota: Impacts Predicted in EIS All waste rock is acid generating Water quality exceedences in Partridge River, EmbarrassRiver, Colby Lake, St. Louis River Tailings basin will leak contaminants to groundwater Increased mercury loadings from waste rock to LakeSuperior watershed Direct impacts to > 1,000 acres of wetlands; inadequatemitigation plan Assumes maintenance-free closure; no financialassurance information EPA rated EIS an EU3 (environmentally unacceptable)STRATUS CONSULTING 40. NorthMet ProjectSTRATUS CONSULTING Source: NorthMet DEIS, 2009. 41. NorthMet Project: Impacted WetlandsSTRATUS CONSULTING Source: NorthMet DEIS, 2009. 42. Summary Upper Great Lakes region is at risk, with widelydistributed base metal, precious metal, and uraniumdeposits Deposits are sulfide-rich, and mining them can bemore environmentally harmful than historic ironmining, especially to water quality Estimates of potential adverse effects in this studyare likely lower than actual effects Mining of similar deposits has consistently causedwater quality problems Regulatory agencies are not adequately staffed toreview proposals or manage new miningSTRATUS CONSULTING 43. References See files for report, data, and websitereferences.STRATUS CONSULTING


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