Torch Lake: Enhanced Recovery

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Torch Lake Enhanced Recovery
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• 1868 first stamp mill opened on Torch Lake
• 1/3 of lake filled in with stamp sands
• 1968 last stamp mill on Torch Lake closed
• 1972 27,000 gal of leaching liquor spilled in
  lake
• 1973 fish with tumors found in lake
• 1983 fish advisory posted
• 1983 IJC lists Torch Lake as Area of Concern
• 1986 Torch Lake becomes Superfund site

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• 1992 EPA completes assessment and formulates
  remediation plan
• 1997 remediation performed in watershed (Scales
  Creek)
• 1997 Public Action Committee formed
• 1998 fish spawning reef constructed
• 1999-2003 stamp sands on shore covered with top
  soil
• 2004 remediated shore areas delisted from EPA
  Superfund list

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Dissolved Cu in Torch Lake
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Areal picture of lake with bathymetric
contours overlain
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Post-mining sediments
Mining-period sediments
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X-rays of Torch Lake sediment cores showing
varves (layers) in stamp sands
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Post-mining sediments
Stamp sands
Note the high water content and lack of cohesion
in the Torch Lake sediments.
Torch Lake
Lake Superior
Portage Lake
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Sediment core from Torch Lake with mine residues
overlaying fresh sediments.
Water with suspended clay
Layer of stamp sand on top of recovered sediment
Brown, post-mining sediments
Stamp sands underneath recent sediments
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Canadian Interim Sediment Quality Guideline
Cessation of mining
Stamp sands
Probable effects level
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Current Lake Status

• Sediments are accumulating very slowly (2 mm/yr)
• Copper concentrations remain 2 orders of
  magnitude above recommended concentrations and 1
  order of magnitude above known toxic effects
  level
• Some evidence exists of resuspension and mixing
  of stamp sands into fresh sediments.

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Useful Web Sites
http//www.epa.gov/glnpo/aoc/trchlke.html - EPA's
web page on AOC, Superfund activities http//www.
torchlake.org/index.html - Public Advisory
Counsel (PAC) web page http//www.ijc.org/rel/bo
ards/annex2/tables/torchlak.html - IJC web
information on Torch Lake http//www.epa.gov/glnpo
/sediment/realizing2/RR2report.PDF - an EPA web
page on remediation of sites with contaminated
sediments