Potential environmental health impacts in Alaska Kendra Zamzow - - PowerPoint PPT Presentation

• Potential environmental health impacts in Alaska

Kendra Zamzow Alaska Collaborative on Health and the Environment April 30, 2014

• ARD

Y ellowboy

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ARD in underground tunnel at Kensington D Chambers

East Fork Carson river, CA, 1969. Lahontan Regional Water Quality Board www.swrcb.ca.gov/rwqcb6

• pH, redox (reduction-oxidation)
• Rock types: sulfides, oxides, silicates, carbonates
• PAG, NAG, Acid drainage, metal leaching
• Element symbols:

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Aluminum Al Manganese Mn Copper Cu Cadmium Cd Zinc Zn Mercury Hg Arsenic As Selenium Se Antimony Sb Sulfate SO4

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Iron Fe Forms of iron: Fe 2 +, Fe 3 + dissolved iron Fe(OH)3 yellowboy (solid) Fe 20 3 rust (solid) FeS iron sulfide (solid)

ARD in underground tunnel at Kensington D Chambers

We Wetlands Acid r rock k drai ainage ge Neutral Drai ainage age

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Mill

pit/ tunnels

waste rock

Uneconomic economic

tailings

(finely ground ore, process chemicals)

Market

A mine: two waste streams

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• “Rock” is a mixture of many materials. For the purposes of

mine waste treatment, rock is categorized as potentially acid generating rock (PAG), non-acid generating rock (NAG)

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PAG Sulfides NAG Carbonates Oxides, silicates, iron carbonate

Iron, Aluminum,

Manganese

Copper, zinc, cadmium Lead, Mercury

Contaminant release is not dependent on the ore being mined -- it’s dependent on what is in the rock matrix

PAG: Acid dissolves

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• Oxygen and water act on pyrite

Iron sulfide + O2 + H2O = Fe2+ + sulfate + 2 H+

• Bacteria convert iron ions

Fe2+ Fe3+

• Iron and water acting on pyrite

produces a great deal of acid

Iron sulfide + Fe3+ + H2O Fe2+ + sulfate + 16 H+

Perry Canyon, NV 2007

the only chemistry equations in this slideshow

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Selenium Arsenic Antimony Molybdenum

Some elements in the rock matrix dissolve better under higher pH and oxidizing conditions

NAG: Metal “leaching”

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Iron Aluminum

Fe, A

PAG

Acid metals

(Copper, Zinc, Mercury, Iron, Aluminum)

Iron Armor

metals precipitate based on pH and concentration

Aluminum flocs

Impacts along stream length

pH

East Fork Carson river, CA, 1969. Lahontan Regional Water Quality Board www.swrcb.ca.gov/rwqcb6

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Fe, A Impacts along stream length

pH Alkaline metals

(Selenium, Arsenic, Antimony)

NAG

metal cycling

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• Copper zinc mine. 1910-1937 and

1989-1993. Then bankrupt.

• Contaminated 18 miles of coho

salmon and steelhead habitat.

• 1994 remedial actions made

some areas worse. Became a Superfund site in 2007. Still working on a final cleanup plan.

• Releases 4-13 million gallons of

acid drainage every year.

Acid drainage: Formosa Mine, Oregon

U.S. EPA, Fact Sheet: Formosa Mine, Douglas County Oregon, March 2007, http://www.epa.gov/region10/pdf/sites/formosamine/Formosa_Mine_FS_2_12.pdf. Several documents available at ttp://yosemite.epa.gov/r10/cleanup.nsf/5c8919bc41f032578825685f006fd670/2e0107830190476a882571f0006623b0!OpenDocume nt

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• Operated from 1989-1998. Went bankrupt.
• Not predicted to harm water.
• Selenium in the waste rock seeps into groundwater. Selenium in trout

is high enough to cause reproductive failure and birth defects.

Metal leaching: Selenium, Beal Mt Mine, Montana

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• Mt. Nansen, Y

ukon, Canada. Gold mine. 1997-19 9 9.

• Oxide and sulfide tailings deposited together. Operator went

bankrupt.

• Cu, As, Cd, Zn
• Government installed water treatment plant that cost $500,000 per
• year. Company bond: $4 45,000.
• T

ails need to be kept saturated to prevent oxidation of arsenopyrite leading to acid drainage – but water needs to be drained to prevent dam failure.

• T
• tal closure and treatment estimated to cost $23 million

Personal review of documents for the Little Salmon/Carmacks First Nation. Many documents available at http://www.emr.gov.yk.ca/aam/mount_nansen.html

Mixed drainage: Mt. Nansen, Yukon

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• Underground mercury mine operated

1930s to 1971

• As, Sb, Hg
• Sulfides and carbonate present.
• Groundwater at 20-30’ deep is neutral pH

and oxidized. Shannon and Wilson, 2007. Me mo to BLM, 56 pg.

• Recent sampling of surface stream found

low pH, yellow-orange water.

• Cleanup plans ongoing

Mixed drainage: Red Devil?

Ann-Marie Palmieri, DEC

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• Iron
• Aluminum
• Copper
• Selenium
• Antimony
• Arsenic
• Mercury
• Habitat
• Suffocation
• “Drunk”
• Deformities
• None
• Growth
• Nerves,

reproduction

Fish are affected by different elements or at different concentrations Fish People

• none
• none
• None
• Hair, nails
• Heart, GI
• Heart,

Cancer

• Nerves

1,000

87 3 5

• 150

0.8

ug/ L

• 50

6 10 2

ug/ L

Wate r quality standards for drinking wate r or fre shwate r aquatic life . From ADEC, 2008, Alaska wate r quality crite ria manual for toxic and othe r de le te rious organic and inorganic substance s. De ce mbe r.

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Mill

pit

Uneconomic economic

Market

Donlin’s mine

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Arsenic Antimony Selenium Sulfate Arsenic, Antimony Manganese Mercury, Cyanide, Sulfate NAG + PAG

http://www.donlingolde is.com/BackgroundDocume nts.aspx

Pit lake

Donlin’s end of life

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Arsenic Antimony Selenium Sulfate Arsenic, Antimony Manganese Mercury, Moly Cyanide, Sulfate

T reatment In pe rpe tuity

control Acid Drainage and Metal Leaching

• PAG rock
• chemically neutralized (usually with lime)
• prevent oxygen from reaching it (place it underwater, place

geotextile covers and/ or soil for vegetation over it)

• NAG rock
• may need to be covered to decrease leaching

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Control systems

• Cover waste rock.

Red Dog, Alaska (1989- current). Lead-zinc mine. Sulfate (total dissolved solids)

• issues. Covering waste rock to

reduce water infiltration.

• Co-mix PAG and NAG + Chemical treatment

Donlin -- more PAG than NAG – mix waste rock together to neutralize. Chemical water treatment of waste rock runoff for As, Sb, Mn, Hg. Good method for Se removal not yet identified.

• Chemical water

treatment

Red Dog. ARD. PAG rock will require chemical water treatment, probably liming.

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Perpetual treatment costs

• Equity Silver, BC (1980-1994) –

Silver mine. ARD. Government holds a $50 million bond for perpetual treatment of Cu, Cd, Zn from waste rock.

• Red Dog, Alaska (1989-current).

Currently bonded for $305 million (up from $21 million in 2005), expecting $10 million per year for perpetual water treatment.

• Silverton, CO – ARD. Needs a $ 1 2 -$ 17 million water treatment plant. $ 1 million per year to operate. Former
• perator has offered $ 6 .5 -$ 10 million.
• Leviathan mine, CA – ARD. About $ 2 0 million spent setting up treatment systems. $ 1 -$ 2 million per year to
• perate.

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• The rock matrix, not the metal being mined, influences

whether the material is acid generating or not

• Metals can be released under acid and neutral-alkaline

conditions

• Legacy mines may cost a lot of money to treat
• Modern mines plan for treatment, but perpetual treatment

requires large bonds.

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It may be many decades before we know if predictions were accurate and if mitigating control systems work as planned.

Kendra Zamzow

CENTER FOR SCIENCE IN PUBLIC PARTICIPATION (CSP2)

kzamzow@ csp2.org 907-746-80 6 5

CS P 2

2 3

7 02 + 28 Fe2+ + 28 H+ --> 28 Fe3+ + 14 H2O

4SO4 2- + 30 Fe2+ + 32 H+ <-- 28 Fe3+ + 16 H2O + 2 FeS2

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Iron oxidizing bacteria Pyrite oxidation

(1) FeS2(s) + 7/2 O2 + H2O = Fe2+ + 2SO42- + 2 H+ (2) 4Fe2+ + O2 + 4H+ = 4Fe3+ + 2H2O (3) Fe3+ + 3H2O = Fe(OH)3 + 3H+ (4) FeS2(s) + 14 Fe3+ + 8 H2O = 15 Fe2+ + 2SO42- + 16 H+

(1) Weathering (pyrite oxidation w/ O2) (2) Bacterial cycling of Fe2+ and Fe3+ Red iron reactions (3) Gunky rusty precipitate (4) Pyrite oxidization (Fe3+)

acid mine drainage cycle

acid drainage from waste rock, Leviathan mine. K. Zamzow

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