Giant Mine Interim Underground Stabilization Plan 2013 Mitigation - - PowerPoint PPT Presentation

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Giant Mine Interim Underground Stabilization Plan 2013 Mitigation - - PowerPoint PPT Presentation

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MV2007L8-0031 Work Plan Review Aug 23, 2013 Giant Mine Interim Underground Stabilization Plan 2013 Mitigation Sequence Strategy A phased mitigation sequence that addresses previously identified geotechnical hazard priority but also

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Giant Mine Interim Underground Stabilization Plan– 2013

Work Plan Review – Aug 23, 2013

MV2007L8-0031

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Mitigation Sequence Strategy

 A phased mitigation sequence that addresses previously identified

geotechnical hazard priority but also recognizes that in some areas we need to understand the situation better before we can develop a detailed plan.

1.

Mitigate high risk non-arsenic stopes with good knowledge base and ease of underground access: 1-18.

2.

Develop a parallel / contingency plan to partly mitigate moderate risk non-arsenic stopes with good knowledge base and ease of access: C3- 12/C5-09.

 This area provides a good area for commissioning of paste

equipment with few environmental challenges and an alternate fill placement area when needed.

3.

Optimize approach and prepare to mitigate high risk non-arsenic stopes with some data gaps and some underground access challenges: B3- 06.

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High Priority Areas With Reasonable Knowledge

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1) 1-18 Non-Arsenic Stope Under Baker Creek 3) B3-06 Non-Arsenic Stope Under Arsenic Stope B2-08 2) C3-12/5-09 Non- Arsenic Stope Under Arsenic Stope C2-12 and Arsenic Chamber 9

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Main Elements of Mitigation Plan

1.

Excavate tailings and stockpile near B1 pit

2.

Drill surface backfill, paste delivery, monitoring, breather boreholes

3.

Rehabilitate underground ground control system as needed

4.

Drill underground backfill, inspection, monitoring, breather boreholes

5.

Install underground paste delivery piping system

6.

Construct underground fill barricades

7.

Produce paste and pump underground to backfill voids

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  • 1. Tailings excavation and stockpiling

Excavate from South Tailings pond by pulling top few m’s which are anticipated to be lower moisture content and trafficable with heavy equipment.

Create mini-stockpiles near B1 pit working area for use during paste production.

Replenish mini-stockpile by direct digging from South Tailings pond as needed.

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Mini Stockpiles Truck Wash

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  • 2. Surface Drilling

 Surface boreholes required for:

Direct placement of backfill into stope voids.

Remote placement of fill barricade (where required)

Delivery of paste to underground boreholes (via. pipe)

Inspection and monitoring (borehole cameras)

Breather holes

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  • 3. Underground support rehabilitation

 C&M contractor currently only maintains minimal underground

development openings according to the NWT Mine Health and Safety Act and Regulations.

 A process to assess hazards for re-entry into old mining areas,

documentation of that process, and maps describing where staff and mining equipment can / can’t go is required prior to development of detailed plans for backfilling of each stope.

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  • 4. Underground drilling

 Underground drilling into voids that cannot be intersected reasonably

from surface required for:

Direct placement of backfill.

Remote placement of fill barricade (where required)

Delivery of paste to underground boreholes (via. pipe)

Inspection and monitoring (borehole cameras)

Breather holes

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  • 5. Underground paste delivery piping system

 In some cases drilling boreholes from surface directly into the targeted

void to be backfilled may not be possible, safe, or environmentally sound.

 Voids under arsenic stopes.  Voids under Baker Creek (e.g. 1-18 stope Upper)  Etc.  Vertical boreholes will be drilled to safely accessible underground

  • penings, piped underground, and pumped into voids through

underground drillholes.

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  • 6. Underground fill barricade construction

 Once ground support is up-to-date, fill fences can be installed.  Barricades do not need to be completely tight to the back and ~ 90-95%

closure of the cross-sectional area of the openings is likely sufficient.

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Existing rockfill Rockfill barricades placed directly where machine accessible, and low slump barricades delivered via. borehole where safe access not available or practical. Void to be backfilled Placed lightly cemented tailings paste backfill Paste backfill delivery hole

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  • 6. Underground fill barricade construction

 Borehole emplaced barricades do not need to be completely tight to the

back and ~ 90-95% closure of the cross-sectional area of the openings is likely sufficient.

 Low slump paste

 Similar to those attempted for FOS with concrete, but using cemented

paste.

 Expanding foam barricades.

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  • 7. Produce paste tailings and pump

underground

 Produce Paste and Place It Underground  Monitor Filling Success Using Camera’s and Cavity Surveys in

Boreholes and Placed Underground

 Show Video

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Field Fill Barricade and Paste Test

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Main Giant Mine Infrastructure Complex Proposed Field Test Area, South Tailings Pond

 We need to test

some elements of the mitigation plan to allow for final engineering and implementation.

 Paste Mixes  Drift Barricades

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Mitigation Plan for 1-18 Stope

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