Cannon Mine Tailings Impoundment Wenatchee, WA

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Cannon Mine Tailings Impoundment Wenatchee, WA

• Jack A. Caldwell Robertson GeoConsultants
• Ian Hutchison Strategic Engineering Science
• Rick Frechette Knight Piesold
• We were all with SRK for this project

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Teton Dam Failure

• On the Teton River, Southeast Idaho

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More Teton

• Failed 1976
• Killed 11
• Height 305 ft
• Length 3,100 ft
• Cost 48 million
• Design Earth Dam

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Causes of Failure

• Foundation Seepage
• Cracked Core
• Internal Erosion
• Piping

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Looking Down to Wenatchee
Same Foundations Above the Town A Silica Quarry
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JOINT VENTURE Asamera Minerals Breakwater
Resources
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Cross Section
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Surrounding Site Conditions
Basalt for Shell Loess for Core Quarry of Filters
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Downstream Face of Embankment
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The Grout Curtain
Cost 1 million Depth gt 200 ft Three Lines of
Grouting
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What Was Actually There
Deep, Undetected Gully 16 million to clean and
clear
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The Mill Site
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Some Mine Stats

• Produced
• 1.25 million oz Gold
• 2 million oz Silver
• Employed 185
• Underground Mine
• Died During Mining 2

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Tailings Deposition 1985 to 1994
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Geotextile as Base for Cover
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Cover Soil over Geotextile
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Aerial View of the Impoundment
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Site Revegetation in Progress
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Revegetated Top Cover
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At ClosureA Riding Stable Dry Gulch Preserve
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