MERCURY ON THE KUSKOKWIM OLD AND NEW. Kendra Zamzow, Ph.D. CSP2

Transcription

1 MERCURY ON THE KUSKOKWIM OLD AND NEW Kendra Zamzow, Ph.D. CSP2 Nevada City, CA May 3, 2012

2 Outline 2 Kuskokwim Region Red Devil historic mercury mine Donlin proposed gold mine

3 Kuskokwim region Donlin Red Devil

4 Kuskokwim mineral belt Red Devil and Donlin are on the Kuskokwim River in the Mineral Belt Both are located between two major faults. Map: Miller 2008

5 Deposits of the central Kuskokwim Mineral Belt Epizonal Hg-Sb and Au Precious metalbearing intrusion related Map: Miller 2008

6 Epizonal Hg-Sb deposits Red Devil Cinnabar (HgS) Stibnite (Sb 2 S 3 ) Realgar (As 4 S 4 ) Orpiment (As 2 Se) Pyrite (FeS 2 ) Map: Miller 2008; Photos: McCrum 2011

7 Epizonal Au-bearing deposits - Donlin Map and photos: Miller 2008 Donlin

8 Red Devil site history Underground and surface mining Cinnabar processed in retorts, million pounds of mercury Retort water, chemicals and tailings flowed into Kuskokwim 1000 Photos: McCrum 2011

9 Red Devil remediation Remediation has occurred sporadically for 25 years, costing $10 million to date 1987 ID Demolition fuels 2010 Fish tissue Begin RI/FS 2012 draft RI Spread 50,000 yd3 of contaminated soil monofill on top of retort and free phase Hg DEC and EPA want NPL listing

10 Red Devil remediation Remediation has occurred sporadically for 25 years, costing $10 million to date 1987 ID Demolition fuels 2010 Fish tissue Begin RI/FS 2012 draft RI Spread 50,000 yd3 of contaminated soil monofill on top of retort and free phase Hg DEC and EPA want NPL listing

11 Red Devil remediation Remediation has occurred sporadically for 25 years, costing $10 million to date 1987 ID Demolition fuels 2010 Fish tissue Begin RI/FS 2012 draft RI Spread 50,000 yd3 of contaminated soil monofill on top of retort and free phase Hg DEC and EPA want NPL listing

12 Remedial Investigation sediment sediment McCrum 2011

13 Remedial Investigation sediment sediment McCrum 2011 Arsenic (mg/kg) Mercury (mg/kg)

14 Remedial Investigation Surface water DEC standard is 50-2,000 ng/l McCrum 2011

15 Red Devil future Two Alaska Native corporations own the land around the old mine site and want to develop it BLM won t transfer the 10 acres of the mine site until remediation is complete, but cleanup has been slowed by disputes with EPA The BLM and EPA agree that the Site poses serious threats - including to Alaska Native communities BLM does not want EPA to have final authority on the cleanup.

16 Donlin Gold, LLC Red Devil 1000

17 Processing Gold Rock with gold, sulfide, carbonate, and trace metals 17 Create high surface area neutralize Get rid of sulfides, dissolve carbonates sulfide concentrate Dissolve gold Recover gold $

18 Filter?? Processing Waste 18 Arsenic Manganese Mercury Capture A mine is a waste treatment facility with a little bit of gold at the end HazMat Waste Arsenic Mercury Manganese Tailings Storage Mercury Mercury Mercury Arsenic 2012 Feasibility Study Section 1.18, 13.1

19 Operating a mine Pit Hg Mill ore processing 19 tailings (finely ground ore, process chemicals) Arsenic, Antimony, Selenium, Moly, Manganese, Mercury Cyanide, Sulfate Tailings Storage waste rock Arsenic Antimony Selenium Sulfate Waste Rock

20 Operation: Tailings storage facility Processing plant waste slurry goes to the TSF Tailings water will contain elevated levels.. of As, Hg, Mn, Mo, Se, and Sb and could be elevated in sulfate >10g/L ; The capacity of the (carbon in leach) circuit to completely adsorb the mercury is limited and soluble mercury remains in the tails solution FS Section 1.14; Section Waste Rock leachate also goes to TSF Arsenic, antimony, selenium, sulfate

21 Closure: Pit Lake repository Tailings Pond will be drained into Pit Lake Tailings water will drain to pit lake over 52+ years Reclaim and contour, leaving a small lake with vegetation around it. Cover will take 5 years. Runoff water quality is to meet WQS within 5 years. Waste Rock leachate will drain into Pit Lake Cover and route runoff to Pit Lake

22 End of a mine Treatment In perpetuity Pit lake tailings (finely ground ore, process chemicals) Arsenic, Antimony Manganese Mercury, Moly Cyanide, Sulfate +? Arsenic Antimony Selenium Sulfate Advances in treatment technologies for dealing with post-closure water discharge should continue to be monitored, specifically with regard to selenium, arsenic, sulphate, and emerging passive treatment technologies FS Section 26.9 waste rock 22

23 Is mercury an issue? The ore at Donlin has 1-3 mg/kg mercury Pathway: fugitive emissions from waste rock and tailings The mercury vaporizes during processing Pathway: worker risk, fugitive emissions Barrick is the world leader in capturing mercury from gold processing; storage as liquid Hg and calomel Pathway: storage and transport accidents Mercury will be in tailings, kept mobile by cyanide Leaks in tailings, groundwater pathways from pit lake

24 How much mercury? Captured: In an in-region meeting on March 12, 2009, Donlin said they expect to capture kg of mercury per day in their processing plant treatment system. ~12-20 tons per year It s not clear how much of that would report to tailings and how much would be captured in liquid form for transport off-site

25 Mercury storage and transport DOE issued interim guidance on Packaging, Transportation, Receipt, Management, and Long-Term Storage of Elemental Mercury in November 2009 HWAD Mercury Consolidation Project, Joint Munitions Command, July 2010

26 Chemical impacts on fish Mercury Reduced reproduction, neurological effects in fish Risk to pregnant women eating fish Selenium Physical deformities, reduced survival, death in fish and waterfowl. Reproductive failure & population collapse. Bioaccumulates & biomagnifies in aquatic food chains Controversy over selenium thresholds; imperfectly understood, interacts w/ Hg Arsenic Sublethal -- Reduced growth/hatch, avoidance Acute suffocation (increased mucus production) Crump and Trudeau Mercury Induced Reproductive Impairment in Fish. Env. Tox. & Chem. 28 (5): ; USFWS Technical review: Smoky Canyon mine site specific selenium criterion report; Lemly, D Pathology of selenium poisoning in fish in Environmental chemistry of selenium ed by WT. Frankenberger Jr. Eisler 2000, Hamilton & Palace 2001, Muscatello et al. 2008, Phibbs et al. 2011; Bhattacharya, S, A Bhattacharya and S Roy Arsenic induced responses in freshwater teleosts. Fish Physiol Biochem 33:

27 Frohbieter 2009

28 Frohbieter 2009

29 Frohbieter 2009

30 Can Red Devil studies provide us with risk info for Donlin? Fish sampling locations in relation to Red Devil and Donlin McCrum 2011

31 Primary reference material Red Devil Geology: Miller, M Late Cretaceous Tectonic Evolution and Metallogeny of Southwestern Alaska. Presentation at Western Alaska Interdisciplinary Science Conference, Dillingham. USGS. Red Devil Remediation: McCrum, M Presentation at Northern Latitudes Mining Reclamation Workshop, Fairbanks. BLM. Donlin: AMEC NovaGold Resources, Inc. Donlin Creek Gold Project. NI Technical report on second updated feasibility study. Pike: Frohbieter, D Mercury in northern pike: changes due to climate, and health impacts on Native Alaskans. USGS. General mine information: GroundTruthTrekking

32 Tsin aen QUESTIONS?