Appendix E Greens Creek Liner Dry Stack Constructiona123.g.akamai.net/7/123/11558/abc123/forestservic.download.akam… · Greens Creek Liner Dry Stack Construction . Appendix C Photographs—

Appendix E

Greens Creek Liner Dry Stack Construction

Appendix C Photographs— Proposed Stage 3 Tailings Expansion

Greens Creek Mine

Admiralty Island, Alaska

E-1

920 Level Existing Mill Facility

Existing dry-stack tailings facility (looking north) Expansion area in foreground

E-2

Looking east-northeast in Hawk Inlet (July 2010) Marine terminal on left; existing tailings facility on right

Hawk Inlet Marine Terminal (areal view looking east)

E-3

Tailings Foundation Preparation

E-4

Vegetation clearing in preparation for expansion of tailings facility

Removal of peat and reclamation materials ahead of foundation preparation for tailings placement

E-5

Foundation preparation (Where necessary—excavating and grading to achieve desired slopes)

Foundation preparation (Where necessary—placement and compac-tion of 6-inch minus rock fill)

E-6

Final foundation for tailings facility (maximum slope 2H:1V; minimum slope 2%)

Installation of sub-drains beneath tailings liner. Purpose of these sub-drains are to reduce groundwater pressure on liner.

E-7

Perforated sub-drain pipe bedded in gravel, wrapped in filter fabric geotextile and covered with the bedding sand layer

Sub-drain pipeline wrapped in filter fabric geotextile

E-8

Bedding and sand layer—placement and grading (1-foot thick layer increased to 2-foot layer on slopes greater than 15%)

Bedding sand layer—grading and compaction

E-9

Placement of 80-mil HDPE liner

E-10

Welding of 80-mil HDPE liner

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Anchor trench for 80-mil HDPE liner (before backfilling of trench)

Anchor trench for 80-mil HDPE liner (compacting trench backfill)

E-12

Installation of geocomposite fabric drain layer over 80-mil HDPE liner

Installation of above-liner Drains (on top of the 80-mil HDPE liner). Purpose of these above-liner drains are to collect and transport any

water seeping through tailings to wet well locations for eventual treatment in water treatment facility.

E-13

Water from sub-drains and above-liner drains routed to “wet wells” installed in the tailings facility. From wet wells, water will be routed to water treatment plant. Ultimately, water is discharged in Hawk

Inlet under NPDES permit standards.

Close-up view of the base of the wet well with connecting drain pipes.

E-14

Placement and compaction of sand service layer (on the top of the geo-composite fabric layer and synthetic liner)

Initial tailings placement on sand service layer

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Instrumentation and monitoring (piezometers, lysimeters, water sample points, etc.)

E-16

Tailings Operation

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Filter presses within mill (“squeeze” water to obtain an approximate 10-12% moisture content)

E-18

Covered tailings storage at mill

Loading tailings into Max Haul truck at mill (Notice the open lid—this closes for transport of tailings to disposal facility)

E-19

Max Haul truck on B road in route to tailings disposal facility

At tailings facility. View of “dirty road” (gray-colored road on left) versus “clean road” (brown-colored road on right)

E-20

Max Haul truck dumping tailings (Notice compacted area in fore-ground)

Spreading of tailings in approximate 1-foot lifts by dozer (Notice compacted tailings in foreground)

E-21

Tailings compaction with vibratory compactor

Truck wheel-wash facility (All vehicles exiting tailings site must pass through this facility).

E-22

Truck wheel-wash facility. Goal is wash truck wheels to prevent tracking of tailings material onto “clean” roads outside the tailings

facility

Interim reclamation on tailings facility (hydro-mulching/hydro-seeding)

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