2712 lines
99 KiB
Markdown
2712 lines
99 KiB
Markdown
---
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type: document
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title: Coal Waste Study
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file: ../Coal Waste Study.pdf
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tags:
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- Amys_Drop_Box
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docDate: 2012-04
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contentType: application/pdf
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contentLength: 12205596
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sha256sum: 56aed8bb277e6dc76d1da14c4114f082ed7fc9892f814aa41d2731b19c42a6d9
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sha1sum: cb845d530e82175ca71a9a80d77ccaf1d491c76e
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---
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xstrata
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coal
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Ss
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Stantec
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Concept Study on Coal
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Waste Disposal Options -
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Donkin Mine
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Concept Study on Coal Waste
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Disposal Options from
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Proposed Mining Activities at
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Donkin Mine - Donkin, Nova
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Scotia
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Report prepared for:
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Xstrata Coal Donkin
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Management Limited
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Prepared by:
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Stantec Consulting Ltd.
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845 Prospect Street
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Fredericton, NB, E3B 2T7
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April 2012
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File 121510478.231
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D<
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xstrata
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coal Stantec
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ENVIRONMENTAL IMPACT STATEMENT FOR THE DONKIN EXPORT COKING COAL PROJECT
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APPENDIX E
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Coal Waste Study
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xstrata
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coal Stantec
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
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Table of Contents
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1.0 INTRODUCTION .
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1.1. MINING DESCRIPTION...
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1.2 PROJECT COMPONENTS...
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2.0 WASTE DESCRIPTION.
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2.1 INTRODUCTION ..
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2.2 COAL HANDLING PROCESS PLANT (CHPP)
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2.2.1 Desliming and Coarse Coal Circuit.
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2.2.2 Mid-Size Circuit.......
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2.2.3 Flotation
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2.2.4 Waste Handling
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2.3 DISTRIBUTION OF MATERIAL SIZES IN PRODUCT STREAM VERSUS WASTE
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STREAM
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2.4 FEASIBILITY OF COMBINED WASTE STREAM.
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2.5 WASTE STORAGE PILE GEOMETRY.
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2.6 WASTE STORAGE PILE VOLUMES.
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2.7 OTHER POTENTIAL WASTE STREAMS .
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2.7.1 Development Waste......
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27.2 Dredge Spoils from Marine Works
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2.7.3 Acid Rock Drainage Potential...
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3,0 POTENTIAL OPTIONS REVIEWED.
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3.1 SURFACE STORAGE — DONKIN SI
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3.1.1 Waste Storage Options
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3.1.1.1 Disposal Option 1....
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3.1.1.2 Disposal Option 2
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3.1.1.3 Disposal Option 3.
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3.1.1.4 Disposal Option 4.
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3.1.2 Borrow Site...
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3.13 Grubbing Materials Stockpile...
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3.1.4 Concept Design Section
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3.1.5 Slopes and Stability.
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3.1.6 Spontaneous Combustion
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3.1.7 Progressive Reclamation and Final Capping.
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3.1.8 Haul Truck Movement
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3.1.9 Phase Construction
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3.2 SURFACE STORAGE - LOCAL REGION
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3.3 UNDERGROUND DISPOSAL - ON SITE -
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3.4 UNDERGROUND DISPOSAL - LOCAL REGION
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3.4.1. Brief Overview of Mine Waste Disposal in Abandoned Underground Workings 3.13
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3.4.2 Brief History of Coal Mining for the Sydney Coalfield... seo AS
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3.4.3. Summary of Coal Mine Productions for Sydney Coalfield 13.15
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3.4.4 Option Evaluation Framework 16
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3.4.5 Discussion of Findings...... 3.20
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121510478.231 i April 2012
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
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‘TABLE OF CONTENTS
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3.4.6 Potential Storage Capacity ..
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3.4.7 Transportation of Mine Wastes.
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3.4.8 Expected Condition of Mine Workings
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3.4.9 Potential Constraints Related to Existing Land Development/Usage and/or
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Sensitivities .
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3.4.10 Summary of Findings and Conclusions
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3.5 OCEAN DISPOSAL
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4.0 CONCLUSIONS ...
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5.0 REFERENCES
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List of Figures
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Figure 1.1 Location of site
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Figure 2.1. A Schematic Block Flow Diagram of the CHPP
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Figure 2.2 Grain Size Distribution of WasteStreams...
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Figure 2.3 Grain Size Distribution of Product Streams.
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Figure 2.4 Grain Size Distribution of Waste Streams..
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Figure 3.1. Capping Detail.
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Figure 3.2 Stage Storage Curves - Volume vs. Time.
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Figure 3.3 General Location of Abandoned Mine Sites Relative to Donkin Mine (Sour.
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Google Maps)..
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Figure 3.4 General Areas of Historic Mine Workings (Source: NSDNR GIS)
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Figure 3.5 Group 1 Historical Coal Mine Sites. a
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Figure 3.6 Group 2 Historical Coal Mine Sites.
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Figure 3.7 Group 3 Historical Coal Mine Sites
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List of Drawings
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Drawing 3.1. Disposal Option 1...
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Drawing 3.2 Disposal Option 2
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Drawing 3.3 Disposal Option 3.
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Drawing 3.4. Disposal Option 4
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121510478.231 ii April 2012
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xX
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xstrata
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coal
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
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‘TABLE OF CONTENTS
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List of Tables
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Table 2.1 Predicted Waste Quantities
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Table 2.2 Plant Feed Material Entering CHPP
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Table 2.3. CHPP Product Yield Efficiency...
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Table 2.4 Product and Waste Distribution of 1 tonne of Feed Material
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Table 2.5 Material Distribution of Product Stream and Waste Stream
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Table 2.6 Summary of Grain Size Distribution for Combined Waste Stream
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Table 2.7 Summary of Grain Size Distribution for each Waste Stream.
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Table 3.2 Sydney Coalfield Coal Production Volumes (1863-1976) ..
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Table 3.3 Summary of Mine Sites Considered ...
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Table 3.4 General Characterization Summary of Abandoned Mine Sites
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Table 3.5 Evaluation of Mine Site Characteristics Against Primary Considerations for
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Redevelopment...
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List of Appendices
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Appendix | - Donkin Site Drawings
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4. Option 1
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2. Option 2
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3. Option 3
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4, Option 4 (Preferred)
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5. Preliminary construction details
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Appendix Il - Cut Sheet data for regional sites
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121510478.231 i
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April 2012
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p<
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xstrata
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS ~ DONKIN MINE
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1.0 Introduction
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Xstrata Coal Donkin Management Limited (XCDM) proposes to build upon the existing
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Donkin Mine infrastructure to construct and operate an underground coal mine facility capable
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of producing coal suitable for the export coal market. It is located on the Donkin Peninsula,
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within the Cape Breton Regional Municipality (CBRM), Nova Scotia (Figure 1.1).
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Figure 1.1 Location of site
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Associated with the mining of the coal resource and the production of the product for export, is
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the residual waste stream(s) of rejects from the coal processing streams on site. The potential
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manner and location for storage of this waste stream and other site waste components is the
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subject of this report.
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14 MINING DESCRIPTION
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The proposed Export Coking Coal Project is to be located at the existing Donkin Mine site on
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the Donkin Peninsula, Cape Breton, Nova Scotia. XCDM proposes a multi-continuous miner
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underground operation producing approximately 3.6 million tonnes per annum (Mtpa) of ROM
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(run of mine) coal that is subsequently washed to provide 2.75 Mtpa of product coal that is
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suitable for the international export coking coal markets. A material handling and processing
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121510478.231 14 April 2012
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if.
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xeiga Stantec
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
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INTRODUCTION
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plant system capable of processing 3.6 Mtpa of raw coal from the Donkin Mine will be
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constructed to produce a coking coal ready for presentation to a barge loading facility and
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marine transportation operation.
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The life of the mine is proposed to be at least 30 years.
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4.2 PROJECT COMPONENTS
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‘The proposed Project is a potential 3.6 Mtpa ROM underground mining operation. Use of four
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continuous miners is currently planned with the ROM coal produced being beneficiated (i
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processed) onsite to produce an estimated 2.75 Mtpa of marketable product coal. This leaves
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approximately 0.85 million tonnes per annum as reject materials or waste that must be disposed
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of as part of the process.
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A raw coal stockpile, reciaim, and sizing system will be constructed to prepare a minus 50 mm
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raw coal feed to the Coal Handling Preparation Plant (CHPP). The 650 tonnes/hour (vh)
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processing plant features a single stage large diameter dense medium cyclone to process coal,
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spirals to process the mid-size material, and flotation to process the fine coal. A product
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sampling and reclaim system will prepare product coal ready for loading onto a barge or truck
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load-out facility.
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Product coal is reclaimed to an overland conveyor that feeds directly to a barge loading facility
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proximal to the Donkin headland in Morien Bay. Coastal barges of 4,000 tonne capacity are
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loaded and then towed by tug to a transshipping location within Mira Bay where the coal is
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transshipped to bulk vessels.
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The reject CHPP materials are similarly prepared for dry disposal and are loaded out by
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conveyor to a site stockpile from where they are available for relocation to permanent storage.
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‘The Project includes the following fundamental components:
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an underground coal mine;
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a coal handling preparation plant (CHPP) with a product sampling and reclaim system to
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prepare product coal and a dry disposal reject handling system;
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+ ancillary services to support the underground mine and CHPP (administration building,
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workshop, coal weighing and sampling facilities, dust suppression systems, conveyors,
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stackers, reclaim units and stockpiles, water infrastructure, mobile equipment efc., a new
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138 kV power line from Victoria Junction to the Project site); and
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* a barge load-out facility proximal to the Donkin headland and barges to transport product
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coal to a transshipping location within Mira Bay.
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+ Ancillary services to support the barge load-out facility (material handling outhaul conveyor,
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radial, luffing telescopic stacker; fuel lines and valving for fueling of vessels; light and power
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and potable water supply).
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121510478.231 12 April 2012
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DB
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xstrata
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coal Stantec
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
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INTRODUCTION
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‘The location and inter relationship of the various site components are established by others and
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for this review of waste disposal options, all infrastructure locations have been considered fixed
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(CBCL 2012).
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121510478.231 13 April 2012
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CT
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xstrata
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coal Stantec
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS ~ DONKIN MINE
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2.0 Waste Description
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24 INTRODUCTION
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In order to facilitate the design of the various storage options under consideration for the waste
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coal rock generated from the coal production process, a breakdown of each phase of the coal
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handling process; from the raw coal retrieved in the mine to the completion of the handling
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process was developed, Two materials types are generated during this process; the product
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(yield) to be marketed and the waste (rejects) which are to be handled in a waste storage
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capacity. Two additional waste streams must be considered for disposal as well; one for waste
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rock generated by mine development for the third tunnel (Tunnel No. 1) in year 4, and dredging
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spoils from the development of the barge load-out facility.
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The annual and total mine life tonnages and quantities that need to be addressed for the Donkin
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project are presented in Table 2.1, and are based on a 30 year mine life.
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Table 2.1. Predicted Waste Quantities
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Day. th 20
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Daily, mh oS — if —
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Annual tonnage, t 850,000 200,000 -
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‘Annual volume, m? 654,000 ~ 180,000 c
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Life of ine 255 rilon 200,000
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Ute of mine. 72.6 milion | 70,000 i280
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Mining operations will occur below the ocean floor at rock depths of greater than 200 m below
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sea level, where existing access has already been established to the mining face. The mine
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design and mining operation is based on the use of standard continuous miner (CM) sections.
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A section consists of one CM, one roof bolter, and three shuttle cars. Depending on the roof
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conditions, the CM advances the entry or crosscut face on average 6 m and then moves to the
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next place to be cut. If the roof conditions allow, extended cuts up to 12 m could be taken. The
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roof bolter then moves into the recently mined place and installs the roof bolts and other
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secondary supports that make up the immediate roof support.
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Given the depth of the reserves at Donkin, large pillars will be left during advance under the
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deeper cover of a significant portion of the reserve. Retreat mining and partial extraction of the
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pillars will be utilized later in the mining sequence,
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121510478.231 24 April 2012
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OC
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xstrata s
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
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WASTE DESCRIPTION,
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The raw coal handling system will receive coal directly from underground, then stockpile on
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surface and then convey and size to minus 50 mm and convey the sized materials to the CHPP
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at 650 t/h. Raw coal emerging from the underground tunnel via the drift conveyor will be
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deposited onto a stockpile. The “as mined” coal was assumed to have a top size of 250 mm.
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The stockpile is necessary to disconnect the mine operations cycle from the plant operations
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cycle to allow for the higher mining rate and fluctuations in underground production.
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2.2 COAL HANDLING PROCESS PLANT (CHPP)
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Discharge from the reclaim conveyor will be directed to a two stage crushing system comprising
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a sizing station to produce a minus 50 mm plant feed material. The crushed raw coal will
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discharge onto the plant feed conveyor which in turn will discharge directly into the desliming
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screen feed box on the top of the CHPP building.
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The coal handling process can be generalized as follows:
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1. Raw coal is extracted from the mine at a maximum aggregate diameter of 250 mm and
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stockpiled at surface.
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2. The raw coal is taken from the stockpile and fed into a 2 stage crusher to produce a 50 mm
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minus material.
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3. The 50 mm minus material is fed into the CHPP, consisting of a three stage process.
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4. Each of the processes handles a specific material size and generates a product stream and
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a waste stream, each with a unique and varying product yield and recovery efficiency.
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5. The Dense Medium Cyclone handles material sizes between 50 mm and 1.4 mm in
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diameter (large size). Spirals will handle 1.4 mm to 0.25 mm (mid-size) and Flotation is
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proposed for the 0.25 mm and below materials (fine size). Since each process has a range
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of efficiency (yield), the percentage of material sizes entering the CHPP will not necessarily
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‘equal the percentage of material sizes being generated in the product and waste streams.
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6. Reject materials from each process will be dried and combined before being transported to
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the waste stockpile.
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A simplified process diagram is presented in Figure 2.1, with further description of the general
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process presented in the following text.
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121510478.231 22 April 2012
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>.<
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xstte
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|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION
|
||
|
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Figure 2.1. A Schematic Block Flow Diagram of the CHPP
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= DONKIN CHPP
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secouire J SIMPLIFIED BLOCK DIAGRAM
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—— i
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=
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|
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sof oeearcane
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2.2.1 Desliming and Coarse Coal Circuit
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Plant feed coal will be slurried in the desliming screen feed box and fed onto a multislope
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desliming screen. The -1.4 mm wet weight (ww) material and water will be collected in an
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underpan and piped to a desliming cyclone feed sump. The -50 to +1.4 mm (ww) material will
|
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discharge from the desliming screen and be flushed into a dense medium cyclone (DMC) feed
|
||
sump.
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Product coal will be directed to coarse coal centrifuges for dewatering prior to being discharged
|
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onto a product conveyor.
|
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Reject coal will underflow from the dense medium cyclone into a tile lined screen feed box
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which will direct the reject material onto a reject conveyor.
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||
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2.2.2 Mid-Size Circuit
|
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The desliming screen undersize (1.4 mm (ww) material will be pumped to a cluster of destiming
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cyclones. The cyclones will classify the feed at approximately 0.250 mm, with the underflow
|
||
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(+0.250 mm) gravitating to spirals and overflow (-0.250 mm) reporting to the flotation feed
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sump.
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||
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||
121510478.231 23 April 2012
|
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24
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||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION,
|
||
|
||
The thickened underflow will be dewatered by two fine coal centrifuges before discharging onto
|
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the product conveyor.
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Spiral rejects will gravitate to a high frequency dewatering screen. Dewatered rejects will
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discharge onto the reject conveyor, and screen underflow will report to the thickener.
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2.2.3 Flotation
|
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Desliming cyclone overflow and spiral product thickening cyclone overflow will be combined in
|
||
the flotation feed sump and pumped to a single Jameson Cell
|
||
|
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The concentrate from this cell will gravitate to a screen bowl centrifuge to dewater the flotation
|
||
concentrate, The tailings from the flotation cells will report to the de-aeration tank where a
|
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portion of the flotation tailings will be recycled as sump level control and as a scavenging
|
||
process. The remainder of the tailings will gravitate from the de-aeration tank to the tailings
|
||
thickener.
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||
2.2.4 Waste Handling
|
||
|
||
Due to the proximity of the proposed site to neighbouring townships, as well as concerns with
|
||
the potential impacts of tailings (waste rejects) on groundwater from a conventional tailings
|
||
dam, a full dry disposal system for the CHPP reject has been proposed as part of the CHPP. A
|
||
dry disposal system in this sense is understood to mean disposing of the combined streams of
|
||
dewatered tailings and coarse reject. In the dry disposal reject handling at this stage of project
|
||
development, it has been assumed that belt press filters will be used. Coarse and mid-size
|
||
reject will discharge from their respective screens onto the main reject conveyor.
|
||
|
||
Thickener underflow will be pumped to the filter feed sump and flocculated prior to being fed to
|
||
belt press filters. Dewatered tailings cake from the belt press filters will discharge via chutes
|
||
‘onto the main reject conveyor. This conveyor will convey all reject to the waste stockpile. A
|
||
weigh scale will record the instantaneous tonnage of total reject and tailings material generated
|
||
by the plant. In addition, a reject sampling system will be included for sampling waste prior to
|
||
stockpiling
|
||
|
||
2.3. DISTRIBUTION OF MATERIAL SIZES IN PRODUCT STREAM VERSUS
|
||
WASTE STREAM
|
||
|
||
In order to effectively manage the waste generated from the CHPP, it is necessary to determine
|
||
parameters such as the total waste volume and the physical characteristics of the waste(s). An
|
||
accurate grain size distribution of the combined waste stream coming from the CHPP is
|
||
necessary in order to determine design parameters for the waste rock material, i.e., angle of
|
||
repose, compaction requirements, combined bulk density, etc.
|
||
|
||
421510478.231 24 April 2012
|
||
|
||
|
||
|
||
|
||
oxi
|
||
|
||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION
|
||
|
||
From Fig 2.1, it is shown that each process within the CHPP has a product stream and a waste
|
||
stream. Each process recovers product coal at varying efficiencies, therefore the relative waste
|
||
volume from each process also varies. This variation in process efficiency will produce a waste
|
||
stream with a grain size distribution that differs from that of the plant feed material. The grain
|
||
size distribution of each waste stream from the CHPP is presented graphicallly in Figure 2.2.
|
||
|
||
Figure 2.2 Grain Size Distribution of WasteStreams
|
||
|
||
ape ‘tend Gay
|
||
~ ot | on aiden
|
||
|
||
It is therefore necessary to define the volume of feed material entering into each of the CHPP
|
||
processes in order to determine the waste stream volume generated from each process.
|
||
|
||
Harbour seam samples were obtained in August 2006, and underwent intensive pre-treatment
|
||
making them suitable for CPP design purposes. The grain size distribution, adjusted for 50 mm
|
||
topsize, are reported in Sedgman (2010).
|
||
|
||
In order to define the waste streams from the CHPP, the plant feed material was selected for
|
||
analysis, as this more closely resembles the material that will be entering the CHPP. The
|
||
|
||
121510478.231 25 April 2012
|
||
|
||
|
||
|
||
|
||
xstrata
|
||
|
||
coal Stantec
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION
|
||
|
||
nominal grain size distribution curve was selected for the purposes of determining waste
|
||
characteristics, as it is an average of the six (6) samples obtained.
|
||
|
||
Each stage of the CHPP receives the feed material based on grain size, and based on the
|
||
provided grain size distributions, the percentage of plant feed material entering the CHPP has
|
||
been calculated and is summarized in Table 2.2.
|
||
|
||
Table 2.2 Plant Feed Material Entering CHPP
|
||
|
||
Percentage of Raw
|
||
|
||
Particle Size
|
||
|
||
Material Captured
|
||
|
||
Dense Medium Cyclone | Large Size Soong 4a oo
|
||
Spirals Mid-Size 14 mm 6 +0250 mm o%
|
||
[ rotation [Fines “0.250 mm 3
|
||
|
||
The majority of the plant feed material (92%) is sized between a particle diameter of -50 mm to
|
||
+1.4 mm and will be processed in the coarse coal circuit in the dense medium cyclone. The
|
||
remaining feed material (8%) will be handled in the spirals and flotation processes.
|
||
|
||
In order to determine the grain size distribution of the waste from the three processes
|
||
(combined waste stream), the overall grain size distribution of the feed material as well as the
|
||
product yields of each process are considered. These values were prepared by Sedgman
|
||
(2010) and are reproduced herein in Tables 2.3 for convenience.
|
||
|
||
Table 2.3. CHPP Product Yield Efficiency
|
||
|
||
Minimum Nominal Maximum
|
||
|
||
Dense Medium Cyelone 20% 35%
|
||
Spirals 80% | 20% 90%
|
||
Flotation 40% I 58% 20% |
|
||
|
||
In order to determine grain size distribution of the waste stream, it is necessary to compare the
|
||
percentage of feed material that is handled by each CHPP process with its corresponding
|
||
product yield efficiency to determine the volume rate of each process.
|
||
|
||
‘As an example to determine the waste stream from the DMC, 92 percent of the feed material
|
||
entering the CHPP is handled by the DMC (Table 2.2), which operates at a nominal product
|
||
yield of 89 percent (Table 2.3). In a numerical example, one tonne (1000 kg) of ROM feed
|
||
material into the CHPP, 920 kg would be expected to pass through the DMC. Since 89 percent
|
||
(nominal) of this material will be recovered for product, a yield of 819 kg of product (81.9%), and
|
||
401 kg of reject (10.1%). The same calculation could be carried out for the other processes.
|
||
Table 2.4 indicates the product and waste for the example 1 tonne (1000 kg) of material passing
|
||
through the CHPP, with nominal yield as per Table 24.
|
||
|
||
121510478.231 26 April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xstre
|
||
rate Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION,
|
||
|
||
Table 2.4 Product and Waste Distribution of 1 tonne of Feed Mate!
|
||
|
||
Product,
|
||
|
||
Spi
|
||
Flotation
|
||
|
||
The product recovered from the CHPP is 876.4 kg, about 87.6 percent of the total material
|
||
entering the CHPP, while the waste stream generated from a 1000 kg of feed material is 123.6
|
||
kg, about 12.4 percent of the total entering the CHPP. The more efficient a process, the less
|
||
waste generated, thus the grain size distribution of a combined (processes with varying
|
||
efficiencies) product stream and combined waste streams will differ slightly from one another.
|
||
Table 2.5 shows the variance in material distribution of the product stream and of the waste
|
||
stream from each process.
|
||
|
||
Table 2.5 Material Distribution of Product Stream and Waste Stream
|
||
% of Product
|
||
|
||
fof Waste
|
||
|
||
Unit Product, kg Waste, kg
|
||
DMC. 819 1
|
||
Spirals 40
|
||
|
||
Flotation 174 26
|
||
Total “876.4 123.6
|
||
|
||
In a comparison of the two combined streams, the product stream received a greater
|
||
percentage of material from the DMC than the waste stream, and less from the spirals and
|
||
flotations, resulting in a material with a higher percentage of gravel and sand. This is presented
|
||
graphically in Figure 2.3.
|
||
|
||
121510478.231 27 April 2012
|
||
|
||
|
||
|
||
|
||
»<
|
||
|
||
x
|
||
strata ss
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION
|
||
|
||
Figure 2.3 Grain Size Distribution of Product Streams
|
||
|
||
|
|
||
| Mf
|
||
og dct |
|
||
|
||
‘Sp Sant ‘Sitand Clay
|
||
|
||
In a similar manner, grain size distributions were determined for the combined waste stream,
|
||
using the maximum, nominal, and minimum waste yield from Table 2.5. A summary of the grain
|
||
size distribution for the combined waste stream is shown in Table 2.6.
|
||
|
||
Table 2.6
|
||
Description
|
||
|
||
Summary of Grain Size Distribution for Combined Waste Stream
|
||
Soil Fractions.
|
||
Gravel Sand SiltiClay
|
||
|
||
Maximum Waste Yield 66%. 32%
|
||
Nominal Waste Yield. 61% 37%.
|
||
Minimum Waste Yield | _____60%. 38%.
|
||
|
||
The waste stream grain size distribution is presented graphically in Figure 2.4.
|
||
|
||
121510478.231 28 April 2012
|
||
|
||
|
||
|
||
|
||
De
|
||
|
||
xstrata
|
||
coal
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
WASTE DESCRIPTION,
|
||
|
||
Figure 2.4 Grain Size Distribution of Waste Streams
|
||
|
||
=| \ |
|
||
|
||
cf Ne
|
||
|
||
T
|
||
|
|
||
|
||
ws ft
|
||
Sear ent ‘Sitend Cay
|
||
a a od
|
||
eine fewaansre] mine | erm Pa eR ‘omarion
|
||
Wess res [einen | —Rapss [soe [a “Gre Ws Shyer aa
|
||
|
||
The combined waste stream showed a range of gravel sizes from 60 to 66 percent with an
|
||
average of 62 percent, a range of sand sizes from 32 to 38 percent (average 36 percent) and a
|
||
|
||
siltclay sizes of 2 percent.
|
||
|
||
Grain size distributions were also determined for each waste stream and are shown in Table
|
||
|
||
27.
|
||
|
||
Table 2. Summary of Grain Size Distribution for each Waste Stream
|
||
Waste Stream DMC 87% 13%
|
||
|
||
Waste Stream Spirals
|
||
|
||
Waste Stream Flotation
|
||
|
||
17%.
|
||
|
||
121510478.231 29
|
||
|
||
April 2012
|
||
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xsl
|
||
ar Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION
|
||
|
||
As shown in Table 2.7, the waste streams from the DMC and Spirals fall within the gravel and
|
||
sand soil fractions, while the majority of the waste from the flotation are sand fractions, albeit
|
||
fine sand. Given that flotation make up 10 percent of the total combined waste stream and the
|
||
fraction of silt and clay from the flotation waste stream is 17 percent, the silt/clay sizes comprise
|
||
only 1.7 percent of the total weight of the combined waste stream, and is interpreted as not
|
||
being significant in defining the material general physical properties and behavior with respect to
|
||
the design of waste pile geometry.
|
||
|
||
2.4 FEASIBILITY OF COMBINED WASTE STREAM
|
||
|
||
The feasibility of combining the waste streams, to be stored simultaneously in compacted lifts in
|
||
a designated waste storage area is enhanced by the low percentage of silt/clay sizes in the total
|
||
waste stream.
|
||
|
||
The void ratio of the DMC material was determined to be approximately 0.3 based on reported
|
||
literature values for similar materials (Hunt 1986). With this void ratio, a calculated volume of
|
||
0.3 m* of void space for every 1000 kg of this material is determined. This is a sufficient volume
|
||
to include the small percentage of sands and fines in a combined waste stream while not
|
||
altering the overall volume or soil properties of the mass.
|
||
|
||
2.5 WASTE STORAGE PILE GEOMETRY
|
||
|
||
‘Sedgman (2010) in the CHPP design report presents the following soil parameters for the run of
|
||
mine and reject materials:
|
||
|
||
* Bulk Density design values (Volume Calculations) ~> y=1,100 kg/m?
|
||
+ Angle of Repose — 0=37°
|
||
«Surcharge angle -> B=20°
|
||
|
||
In the absence of additional testing, for continuity the values provided in the CHPP design are
|
||
retained and carried through this report.
|
||
|
||
In accordance with Nova Scotia provincial guidelines for surface coal mine reclamation plans,
|
||
the land form must be stable and hydrologically compatible with the surrounding area. The
|
||
objective for land forming to provide stability through reduced slope angles is preferred and
|
||
slopes greater than 3 horizontal to 1 vertical (18 degrees) must be flattened by step berming to
|
||
reduce the overall slope to less than 18 degrees. For the conceptual design stage, a factor of
|
||
safety (FS) of 2.0 was chosen for the waste pile slope construction, which corresponds to a
|
||
slope angle of 20 degrees which by coincidence is the same as the surcharge angle of 20°
|
||
provided by Sedgman (2010). The corresponding minimum side slopes to be used in the
|
||
design of the proposed waste storage piles would therefore be 2.75 horizontal: 1 vertical.
|
||
|
||
121510478.231 2.10 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION,
|
||
|
||
2.6 WASTE STORAGE PILE VOLUMES
|
||
|
||
The coal waste pile volumes generated are estimated based on the reported proposed waste
|
||
stream of 0.85 Mt per year, with a field bulk density of 1.1 t/m®. As noted in Section 2.4 with a
|
||
combined waste stream material, the fines can be disposed of in the combined waste stream,
|
||
increasing the bulk density but without affecting the overall volume of the DMC and spirals
|
||
waste. The field bulk density would be increased with the inclusion of the finer materials within
|
||
the existing void spaces, with a further increase realized by means of compaction during the
|
||
placement of waste materials. Utilizing this method, the resulting in-place field bulk density
|
||
could be increased to 1.3 tim’, (at field moisture content), which converts to a decrease in the
|
||
total volume required for storage by approximately 18 percent
|
||
|
||
Waste material placed in this manner would result in a proposed waste stream estimated at a
|
||
volume rate of 654,000 m’/yr.
|
||
|
||
2.7. OTHER POTENTIAL WASTE STREAMS
|
||
|
||
The most significant waste stream requiring storage or disposal is the reject coal waste from the
|
||
CHPP process. However two other potential small sources of similar waste will likely be
|
||
generated during the project life.
|
||
|
||
4. Development rock for Tunnel #1 construction.
|
||
2. Dredge spoils from marine works associated with barge load-out facility
|
||
2.7.1 Development Waste
|
||
|
||
The development of a third access tunnel to the coal face is planned for year 4 of the project
|
||
development and would be approximately 200,000 tonnes of waste likely composed principally
|
||
of mudstone and sandstone. It is likely that construction would be carried out using a tunnel
|
||
boring technique and so the waste would likely be similar to a uniformly graded minus 75 mm
|
||
minus crushed rock.
|
||
|
||
At present 450,000 tonnes of development waste from the past construction of tunnels 2 and 3
|
||
exists on the surface at the site. This material was the subject of an acid characterization
|
||
review in 2010 (Stantec, 2010) and was found to be non-acid generating and a non-sulphate
|
||
bearing material and is therefore of limited environmental concern for disposal.
|
||
|
||
For the development of the concept plan for reject coal disposal this 200,000 tonnes of material
|
||
was incorporated into the waste stream from the CHPP and co-deposited with the reject coal
|
||
(approximately 0.8% of the total waste volume).
|
||
|
||
121510478.231 24 April 2012
|
||
|
||
|
||
|
||
|
||
D<
|
||
|
||
xstrata Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
WASTE DESCRIPTION
|
||
|
||
2.7.2 Dredge Spoils from Marine Works
|
||
|
||
It has been predicted that up to approximately 11250 m® of organic silt dredge spoil could be
|
||
generated during the barge load-out facility construction (CBCL, 2012). At present this material
|
||
is proposed to be stored along the outhaul conveyor route in a 75 m x 75m containment area.
|
||
|
||
It is also noted in the CBCL report that this waste could be co-deposited in the CHPP reject
|
||
waste storage area and this would be acceptable to the concept presented herein, dependent
|
||
on the construction timing and stage of development. The placement of this benign silt waste in
|
||
the rejects pile would have little to no impact on potential storage volume (0.26% of Phase 1).
|
||
|
||
2.7.3 Acid Rock Drainage Potential
|
||
|
||
Characterization of the waste rock for acid generation potential was reviewed by Stantec
|
||
(December, 2011) and it was concluded that the CHPP waste will have a strong potential to
|
||
generate acid rock drainage (ARD), if stored on the surface exposed to the atmosphere and
|
||
precipitation. The acid runoff would need to be contained and collected and treated from any
|
||
surface storage facility,
|
||
|
||
Mitigation of acid drainage effects can be reduced and possibly minimized by progressive
|
||
reclamation and a focused deposition management plan.
|
||
|
||
Storage by either sub aqueous methods or capping without exposure to direct precipitation
|
||
would also limit to eliminate ARD risks and should be considered as a benefit for conceptual
|
||
design.
|
||
|
||
121510478.231 212 April 2012
|
||
|
||
|
||
|
||
|
||
»<
|
||
|
||
xstrata
|
||
sag ‘Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS ~ DONKIN MINE
|
||
|
||
3.0 Potential Options Reviewed
|
||
|
||
During the thirty year operation of the mine, there will be approximately 20 million cubic metres
|
||
of waste generated that will require storage. Due to the proposed large volumes, several
|
||
disposal options were reviewed, and are discussed in the following sections.
|
||
|
||
Surface storage on Donkin Mine site;
|
||
Surface storage in the local region;
|
||
Underground storage on Donkin Mine site;
|
||
Underground storage in the local region; and
|
||
Ocean disposal
|
||
|
||
34 ‘SURFACE STORAGE - DONKIN SITE
|
||
|
||
The Donkin Peninsula consists of a relatively small land mass with variable topography and
|
||
identified wetland areas located throughout. As noted, it is necessary to design sufficient
|
||
storage for 20 million cubic metres of waste and available space for surface storage is limited.
|
||
A review of the available area proved sufficient storage capacity at one location was impractical,
|
||
therefore designing waste piles in separate locations was necessary.
|
||
|
||
The construction of large piles of waste coal that extend above the surrounding topography
|
||
would not be aesthetically pleasing and would potentially adversely affect the air quality due the
|
||
dust generated from the exposed piles.
|
||
|
||
Run-off water resulting from precipitation on the waste piles and presenting as surface runoff, or
|
||
having percolated through the waste piles will be required to be collected and treated during the
|
||
LOM; with a permanent treatment system in place should the waste piles remain exposed into
|
||
reclamation. The waste water would be piped, pumped and/or ditched to holding ponds and a
|
||
treatment plant. Treated water would pass through the existing serpentine ponds and be
|
||
released to the environment. Sludge generated during the water treatment would be disposed
|
||
of within the working waste piles. An innovative method for suppressing ARD is an emerging
|
||
technology that uses an engineered, flow-able or pumpable foam (pHoam"™) that is introduced
|
||
by means of injection through boreholes. The concept basis is to treat large volumes of mine
|
||
waste using low volumes of water. Although stil in a development stage and additional study is
|
||
required, the concept does indicate promise particularly for a progressive reclamation
|
||
application where ARD could be delayed through pHoam™ application until the operations cell
|
||
could be capped and reclaimed. As the project advances it would merit consideration of this
|
||
method. A cost deferral or offset with water treatment costs could be realized in the long term
|
||
with ARD abatement by progressive reclamation.
|
||
|
||
Spontaneous combustion (sponcom), a process whereby certain materials can ignite through
|
||
internal reactions, is also an observed phenomenon in exposed coal stockpiles. Although
|
||
studied for over 200 years, the exact cause is not well understood. There are several indicators
|
||
|
||
121510478,231 34 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
xstrata
|
||
Coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
such as heat, smell, sweating, haze, smoke and unusual coloring that are used to detect
|
||
sponcom. Affected areas are dealt with as early as possible and it would be required to be
|
||
controlled through a spontaneous combustion management system.
|
||
|
||
Limitation and ultimately the elimination of these issues could be possible through progressive
|
||
reclamation and final capping of the waste piles with an impermeable layer, with the intent of
|
||
limiting the exposed surface area of waste coal as much as possible during construction.
|
||
Progressive reclamation would consist of capping completed portions of the waste pile.
|
||
Capping in this case could consist of placing a double non-woven geosynthetic clay liner (GCL)
|
||
over a graded and compacted coal waste surface, with reclaimed grubbings then placed over
|
||
the GCL. Hydroseeding or other means of introducing grasses could be employed to create a
|
||
rootmat to limit erosion of the topsoil layer.
|
||
|
||
Impact on the existing wetland areas of the Donkin Peninsula is unavoidable with surface
|
||
storage on site. Limited available surface area may dictate there is not sufficient area available
|
||
for the creation of new wetland areas or avoidance of existing wetland areas. Wetland
|
||
compensation to ensure a no-net-loss of wetland function (as required by provincial and federal
|
||
policy) will be extensive over the life of the mine and on site compensation opportunities are
|
||
limited
|
||
|
||
The following sections address various waste storage options that attempt to mitigate these
|
||
issues, and the design and construction of the proposed waste pile cells.
|
||
|
||
No further development of an estimate of wetland impact has been carried forward in this waste
|
||
option concept. The issue of land use and wetlands is the subject of work by others and this
|
||
report provides the expected (anticipated) land area use for waste storage as an input
|
||
parameter to this work.
|
||
|
||
3.1.1 Waste Storage Options
|
||
Four disposal options have been reviewed as viable site storage options and are as follows:
|
||
|
||
1. Minimize Height Exposure;
|
||
2. Optimize Height and Spatial Exposure;
|
||
|
||
3. Minimize Spatial Exposure; and
|
||
|
||
4. Minimize Spatial Exposure, with Stage Storage Construction.
|
||
|
||
The fourth option (Option 4) was developed to the concept level with regards to constructability
|
||
and ancillary waste piles as it is the preferred combination of storage and phase construction.
|
||
|
||
3.4.4.1
|
||
|
||
posal Option 1
|
||
|
||
In consideration of the visual aspect of waste storage, i.e., minimizing the height exposure of the
|
||
waste piles, site topography and features were reviewed with the intent of infiling lower areas
|
||
|
||
121510478.231 32 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
and designing the top elevation of the piles so as to blend in with the existing topography as
|
||
much as possible. Limiting the top elevation of the waste piles meant more surface area was
|
||
required, Three areas were selected for waste disposal, as shown on Drawing 3.1 below (also
|
||
included in larger format in Appendix 1), and it was determined that a total land mass of
|
||
approximately 125 ha would be occupied by the waste coal, over the proposed 30 year mine
|
||
life. The top of pile elevations included the proposed east waste pile at 40 m, the west waste
|
||
pile at 26.5 m and the north pile at 30 m, which was in the order of 25 m above existing
|
||
topography but not exceeding the high point of land on the peninsula.
|
||
|
||
Drawing 3.1 Disposal Option 1
|
||
|
||
In conclusion, there would not be sufficient land mass available on the peninsula to store the
|
||
waste rock in a manner that would not be generally conspicuous from the surrounding area.
|
||
The piles would be prominent and not aesthetically pleasing even at minimum design
|
||
elevations. Utilizing the maximum surface area available would entail the elimination of
|
||
significant wetland area, thereby increasing the costs associated with wetland compensation.
|
||
Construction costs related to site preparation of the containment cells would likely be the worst
|
||
|
||
case scenario.
|
||
|
||
121510478.231 33 April 2012
|
||
|
||
|
||
|
||
|
||
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|
||
|
||
xstrate
|
||
om Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
3.1.1.2 Disposal Option 2
|
||
|
||
Next, consideration was given to optimizing the height and spatial exposure of the waste piles.
|
||
The north waste pile was not considered for waste storage. The footprint of the proposed east
|
||
waste pile would remain unchanged, with a top elevation of 42 m (5% increase from Option 1),
|
||
The footprint of the proposed west waste pile also would remain unchanged, with a top
|
||
elevation of 39 m (almost 50% increase from Option 1). The total land mass area would be
|
||
reduced to approximately 100 ha (decreased by 25% from Option 1), and is shown on Drawing
|
||
3.2 below (also included in large format in Appendix |).
|
||
|
||
Drawing 3.2 Disposal Option 2
|
||
|
||
[x
|
||
|
||
In conclusion, the piles would be constructed at increased design elevations, therefore will be a
|
||
more prominent landscape feature. A decrease in surface area required would subsequently
|
||
decrease the costs associated with wetland compensation and site preparation.
|
||
|
||
3.1.1.3, Disposal Option 3
|
||
In consideration of causing minimal impact on existing site conditions, i.¢., minimizing the spatial
|
||
|
||
exposure; site topography, and features were reviewed with the intent of storing waste in such a
|
||
way that would seek to minimize the costs associated with wetland compensation and site
|
||
|
||
121510478.231 34 April 2012
|
||
|
||
|
||
|
||
|
||
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|
||
|
||
xstr
|
||
age Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
preparation. The footprint of the east waste pile would remain unchanged, with a top of pile
|
||
elevation of 45 m (an increase of 12% from option 1). The footprint of the west waste pile would
|
||
be decreased to 42.6 ha (a decrease of 25% from Option 1), with a top of pile elevation of 49 m
|
||
(an increase of 85% from Option 1).
|
||
|
||
This option would create piles that would be in some cases almost 40 m above existing grade,
|
||
making them more susceptible to wind erosion, thereby being the least attractive option for air
|
||
quality management. The total land mass area required for this option would be approximately
|
||
88 ha (a decrease of 30% from Option 1). The configuration of the waste storage piles is shown
|
||
on Drawing 3.3 below (also included in larger format in Appendix |).
|
||
|
||
Drawing 3.3 _ Disposal Option 3
|
||
|
||
rermeeagrenmenine Va X
|
||
|
||
3.1.1.4 Disposal Option 4
|
||
|
||
The area of the proposed east waste pile consists of existing topography that ranges from a
|
||
forested hillside in the southwest portion of the area to a lightly treed wetland area in the
|
||
northeast. Subsurface conditions are likely to vary significantly between these two areas. It is
|
||
anticipated the subsurface conditions within the forested area to the southwest would generally
|
||
consist of a thin rootmat and topsoil layer over glacial till. Conversely, it is anticipated the
|
||
|
||
121510478.231 35 April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xstrata Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
subsurface conditions in the wetland area will consist of soft sit and clay materials and peat at a
|
||
thickness of up to 1.0 m.
|
||
|
||
Consequently, the area of the east waste pile was reviewed with consideration for developing
|
||
the area in two stages or phases, as shown on Drawing 3.4 below (also included in larger
|
||
format in Appendix |). The first phase would develop the forested hillside area and infill and
|
||
‘compact the coal waste up to a top of pile elevation of 45 m. At the completion of Phase |, at
|
||
approximately 6.5 years, the wetland area would then be developed for storage. The estimated
|
||
storage capacity of Phase Il would be approximately 7 years.
|
||
|
||
Drawing 3.4 Disposal Option 4
|
||
|
||
en atom, 4
|
||
|
||
Given the variability anticipated for foundation conditions of the waste pile areas a concept level
|
||
site construction drawing was developed to assist in defining the extent of these foundation
|
||
conditions. This concept construction information is presented in Drawing 5 located in large
|
||
|
||
format in Appendix |.
|
||
|
||
In conclusion, this option is identical to Option 3, in regards to the geometry of the waste piles.
|
||
The use of stage construction could provide some advantages financially and with
|
||
constructability of the waste cells. Stage construction is discussed in more detail in Section
|
||
3.47.
|
||
|
||
121510478.231 36 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
ata Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
The Option 4 is the preferred Donkin surface storage option with the use of staged construction.
|
||
The following sections regarding the various components necessary to construct the surface
|
||
storage facilities are tied to Option 4 but are also applicable with the other three options (1 to 3),
|
||
however the sequencing and detail would vary. Only Option 4 sequences are detailed further in
|
||
the following sections.
|
||
|
||
The waste pile has been located based on best land use at the time of writing in December
|
||
2011. Subsequent to this geometry others have placed site infrastructure that may be in conflict
|
||
with the pile geometry as shown at the concept level. At present (March 2012), the location of
|
||
the CHPP structures conflict with the western edge of the waste piles and a section of the waste
|
||
may need to be reallocated to accommodate this site development. Similarly the location of
|
||
potential water collection ponds to contain waste pile runoff may also affect the final shape of
|
||
the proposed waste pile in the north easter limit.
|
||
|
||
As the waste pile geometry is conceptual only at this stage, no attempts to modify the shape to
|
||
accommodate these conflicts have been considered for presentation. If material is moved to
|
||
accommodate the CHPP plant location approximately 1.1 million m? of material would require
|
||
relocation and this could be placed in the existing (modified) footprint by raising grades by
|
||
approximately 3 metres on both the East and West Disposal Piles. It is estimated that the
|
||
location of the potential runoff collection ponds will not have a significant effect on footprint or
|
||
shape of the piles.
|
||
|
||
3.1.2 Borrow Site
|
||
|
||
Site preparation for the liner installation would require tree cutting, grubbing of stumps and
|
||
topsoil, and the shaping and grading of glacial till subgrade. In many cases, shaping and
|
||
grading of the glacial till subgrade would be feasible utilizing the existing soil available. In
|
||
wetland areas such as Phase II, additional fill would be required to bring the prepared subgrade
|
||
elevation above the existing water table elevation. For conceptual design purposes, a fill
|
||
thickness in the order of 1000 mm is assumed, although a geotechnical investigation would be
|
||
necessary to confirm the thickness of fill required. Consequently, a borrow area would be
|
||
required for any significant quantities of additional fill. It is assumed that the insitu glacial til
|
||
would be suitable for use as an infill material, ie., material is near optimum moisture content
|
||
and is able to be placed and compacted in lifts (reference Drawing 5, Appendix I)
|
||
|
||
The area of Phase | may be considered as a potential borrow source, depending on the amount
|
||
and quality of glacial tll that is available within the area. Itis conceivable that glacial till material
|
||
could be removed from within the proposed waste cell area and stockpiled nearby until Phase I!
|
||
is ready to be constructed. Removing material from within the footprint of Phase | would
|
||
increase its volume capacity, while simultaneously decreasing the cost associated with infilling
|
||
the wetland areas of Phase Il, as this would cut the truck haul distances significantly.
|
||
|
||
121510478.231 a7 April 2012
|
||
|
||
|
||
|
||
|
||
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|
||
|
||
xstrata
|
||
7c Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Site preparation of Phase III would also require fill material to infill some wet, low-lying areas.
|
||
Similar to the cut and fill method proposed for Phase | and Il, and contingent on the amount and
|
||
quality of the glacial till, insitu material from the hillside area may be removed and used to infill
|
||
the lower areas.
|
||
|
||
Phase Ill could be prepared similarly to the East Pile. Consideration could be given to dividing
|
||
the proposed storage area into smaller, manageable sections to be prepared ahead of the
|
||
constructed waste pile.
|
||
|
||
3.1.3 Grubbing Materials Stockpile
|
||
|
||
A sufficient area will be required for the storage of grubbing materials removed from within the
|
||
proposed waste pile areas. The grubbing materials would consist of stumps and rootmat
|
||
material. Based on an assumed grubbing materials thickness of approximately 300 mm in the
|
||
area of Phase |, about 74,250 m* will be generated. The grubbings may be stockpiled along the
|
||
perimeter of the proposed waste pile. As Phase | is being infilled with coal waste, progressive
|
||
reclamation would include the grubbing materials being removed and placed on completed
|
||
areas of the waste pile, i.e., side slopes. Considering site preparation would commence on
|
||
Phase II prior to completion of Phase |, an additional 175,000 m° of grubbing materials would
|
||
also be generated and stored along the perimeter of the Phase Il area. Similarly, the grubbing
|
||
materials would be removed from the storage area and placed over completed areas of the coal
|
||
waste pile during progressive reclamation. Phase Ill covers an area of approximately 43 ha.
|
||
‘Assuming an average grubbing materials thickness of 500 mm, 220,000 m° of grubbing
|
||
materials would be generated and require storage. For conceptual design, an increase of 30
|
||
percent would result in a proposed volume of grubbing materials of approximately 260,000 m°.
|
||
|
||
It is not expected that grubbing materials would be placed in lifts and compacted but would be
|
||
dumped by off-road haul truck and pushed by a dozer. Due to the organic matter and higher
|
||
moisture content of the grubbing materials, soft soil conditions, rutting and likely unstable side
|
||
slopes could be expected. Therefore, a maximum height of about 6 m would be proposed for
|
||
the grubbing materials.
|
||
|
||
It should be noted that after sitting and drying for a period of time, the stumps could be
|
||
removed, chipped and blended back in with the pile. This method would decrease the bulk of
|
||
the pile and aid in the decomposition of organic matter. This material would be available for
|
||
reclamation purposes in the future.
|
||
|
||
3.1.4 Concept Design Section
|
||
|
||
Site preparation would consist of the shaping and grading of existing glacial till and/or borrow
|
||
material to prepare a competent subgrade for liner installation. At the perimeter of the waste
|
||
piles, a berm would be constructed as per detail 2, Typical Waste Coal Containment Berm
|
||
Detail on Dwg. No. 5 (Appendix I). It would be necessary to construct the perimeter berm so as
|
||
to facilitate the installation and anchorage of the HDPE liner and cushion sand. Upon
|
||
|
||
121510478.231 38 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
x
|
||
- ste
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
completion of the liner and sand cushion anchorage, the remainder of the perimeter berm could
|
||
be constructed.
|
||
|
||
Typically, the liner would consist of a 60 mil HDPE with a sand cushion and a running course to
|
||
Prevent point loads from individual rocks and truck movement that could puncture the liner. A
|
||
sand cushion layer, 300mm thick, would be placed over the subgrade area and lightly
|
||
consolidated. The HDPE liner would be placed over the sand cushion, and fused together over
|
||
the area being prepared. An additional sand cushion layer, 300 mm thick, would be placed over
|
||
the HDPE liner and lightly consolidated. A running course, consisting of a well-graded gravel
|
||
with maximum size of 25 mm, would be placed and compacted in three equal lifts. The running
|
||
course would blend into the perimeter berms. Upon completion of the liner and running course,
|
||
the area would be prepared sufficiently to manage the waste coal. A minimum distance of
|
||
2000 mm should be left between the toe of the inside of the perimeter berm and the toe of the
|
||
coal waste slope for runoff collection and drainage.
|
||
|
||
Design of the waste cell subgrade would be such as to direct any rainfall runoff to a holding
|
||
Pond. Run-off water coming from contact with the waste piles will be required to be collected
|
||
and treated during the construction; with a permanent treatment system in place during
|
||
operations should the waste piles remain exposed, The waste water would be collected by toe
|
||
ditches and then pumped and/or gravity feed to holding ponds and a treatment plant. The
|
||
resulting treated water would pass through the existing serpentine ponds and be released to the
|
||
environment. Sludge generated as part of the water treatment process would be disposed of
|
||
within the working waste piles.
|
||
|
||
The conceptual design of a runoff control and ARD treatment system is being carried out under
|
||
a separate cover.
|
||
|
||
‘An innovative method for suppressing ARD is an emerging technology that uses an engineered,
|
||
flow-able or pumpable foam (pHoam™) that is introduced by means of injection through
|
||
boreholes in the stockpile. The intent is to treat large volumes of mine waste using low volumes
|
||
of water. The active ingredients of pHoam™ work is to suppress the ARD reactions in the pile
|
||
and thus mitigate the production of acidic water. Although much study remains to advance this
|
||
emerging technology, with the developers currently seeking demonstration sites to develop the
|
||
product, the potential of this technology could be beneficial in a mine waste application such as
|
||
the waste piles (Gusek, James, Masloff, Brian and Fodor, John, (2012).
|
||
|
||
3.1.5 Slopes and Stability
|
||
|
||
Section 2.5 describes the rationale of the design side slope selection for conceptual design.
|
||
Past experience at similar sites in Industrial Cape Breton have shown that the waste coal may
|
||
have a greater amount of fines than what has been shown in the grain size curves given. This
|
||
could be due to the coal breaking down with handling, j.e., dumping, spreading, and
|
||
compaction. Freeze and thaw cycles may also contribute to the breakdown of the coal.
|
||
|
||
121510478.231 3.9 April 2012
|
||
|
||
|
||
|
||
|
||
><
|
||
|
||
xstrala Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Consideration could be given to lowering the side slopes to that previously considered for other
|
||
local reclaimed waste piles, which are in the order of 5H: 1V. Lowering the side slopes will
|
||
decrease the holding capacity of the waste piles and would necessitate increasing the height of
|
||
the piles and/or increasing the footprint of the piles.
|
||
|
||
3.1.6 Spontaneous Combustion
|
||
|
||
Spontaneous combustion (sponcom), a process whereby certain materials can ignite through
|
||
internal reactions, is also an observed phenomenon in exposed coal stockpiles. Although
|
||
studied for over 200 years, the exact cause is not well understood. There are several indicators
|
||
such as heat, smell, sweating, haze, smoke and unusual coloring that are used to detect
|
||
sponcom, and affected areas are dealt with as early as possible. It would be required to be
|
||
controlled through a spontaneous combustion management system.
|
||
|
||
3.1.7 Progressive Reclamation and Final Capping
|
||
|
||
As side slopes are completed, progressive reclamation with the development of an impermeable
|
||
cap to limit oxygen and precipitation infiltration would thereby limit erosion of the side slopes, aid
|
||
air quality by limiting the exposure of coal waste to wind action, reduce the potential for
|
||
sponcom, and reduce the volume of run-off water generated through the waste pile. Therefore
|
||
reclamation planning should be integral to the waste development plan in final design.
|
||
|
||
Limitation of potential site ARD issues could be possible through progressive reclamation and
|
||
final capping of the waste piles with an impermeable layer, with the intent of limiting the exposed
|
||
surface area of waste coal as much as possible during construction. Progressive reclamation
|
||
would consist of capping portions of the waste pile once they are completed.
|
||
|
||
The application of pHoam technology could also be considered as a progressive mitigation step
|
||
during operations to limit the amount of ARD requiring treatment. If the generation of ARD can
|
||
be limited within the stored waste then the cost of operating the water treatment plant could be
|
||
offset by the cost of the progressive reclamation method selected.
|
||
|
||
Final capping for surface storage waste piles, could consist of placing a double non-woven
|
||
geosynthetic clay liner (GCL) over a graded and compacted coal waste surface, with vegetated
|
||
reclaimed grubbings acting as the stabilizing cover placed over the GCL. Hydroseeding or
|
||
other means of introducing grasses could be employed to create a rootmat to limit erosion of the
|
||
topsoil layer. Figure 3.1 indicates the conceptual capping detail of a completed pile.
|
||
|
||
121510478.231 3.10 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
aga _
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Figure 3.1 Capping Detail
|
||
|
||
RAINFALL
|
||
VEGETATION LAYER RUN-OFF
|
||
|
||
RECLAIMED GRUBBINGS/TOPSOIL
|
||
|
||
CCTEINTHETG GAY DER ASS 5)
|
||
|
||
2% SLOPE MINIMUM Ss
|
||
|
||
300 To
|
||
1500 mm
|
||
|
||
COAL WASTE wes
|
||
|
||
(PREPARED SUBGRADE,
|
||
FINE GRADED AND COMPACTED)
|
||
|
||
3.1.8 Haul Truck Movement
|
||
|
||
During initial operations, the waste coal generated will be taken from the CHPP by conveyor to.
|
||
the waste rock stockpile. Conceptual plans have the location of the waste stockpile along the
|
||
perimeter of the proposed location of the east waste pile. It is conceivable that the waste rock
|
||
could be carried by conveyor to the east waste cell, where it would then be spread and placed in
|
||
lifts with a bulldozer. After a period of time, it may become feasible to utilize off-road trucks to
|
||
haul the waste rock to all points within the east waste pile. Haul truck movement would be
|
||
limited to the area of the east waste pile.
|
||
|
||
At the completion of the east waste pile at year 13.3, waste rock would be hauled to the west
|
||
waste pile. This would necessitate a change in the haul truck route as the waste rock will be
|
||
required to move from the east side of the site to the west side. A potential change in CHPP
|
||
waste conveyance could also be considered to the west pile (Phase Ill) so that a similar
|
||
sequence of load and haul could be employed.
|
||
|
||
3.1.9 Phase Construction
|
||
|
||
Phase construction could be carried out for the cell construction and could be beneficial for the
|
||
following reasons:
|
||
|
||
1. Distribute cash flow requirements for the construction of waste facilities over a longer period
|
||
of the project life.
|
||
|
||
2. Site exposure as needed (limit exploitation of land until required)
|
||
|
||
3. Reserve construction in consideration of future potential addit
|
||
|
||
121510478.231 31 April 2012
|
||
|
||
|
||
|
||
|
||
><
|
||
|
||
xstrata Stant
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Phase construction could be beneficial financially to the project as construction would be carried
|
||
out on an as-needed basis, thereby minimizing cash flow to when it is required, Capital that
|
||
would normally be spent in the first year of operation to prepare a large waste storage area
|
||
instead could be spent over a span of several years, and within a more manageable budget.
|
||
|
||
At the commencement of the project, Phase | could be prepared with a storage capacity of
|
||
about 6.5 years. Prior to Phase | storage area reaching capacity, an additional contract could
|
||
be carried out to prepare Phase II for storage capacity for another 6.8 years. The stage storage
|
||
curves for Phase |, Il and II are shown graphically on Figure 3.1
|
||
|
||
Phase construction would only expose a portion of the site necessary for a couple of years of
|
||
storage. The limited area exposed would lessen the effects on air quality as opposed to a large
|
||
open area. The water collection system would only require handling the runoff from a limited
|
||
area, as opposed to a large catchment area. Reclaimed grubbing materials could be placed on
|
||
portions of the waste pile that have been shaped to design grade. As the site is exposed,
|
||
completed portions of the waste pile could be capped and seeded so as to limit the runoff that
|
||
has to be collected and treated.
|
||
|
||
During the operational life of the mine, there may be scenarios which arise that could provide for
|
||
commercial use of the waste coal, thereby negating the requirement for the large land areas
|
||
which are currently required. One such scenario is the potential for technology to develop and
|
||
‘emerge that will utilize the coal waste and render it marketable. Another is that mining
|
||
operations may develop in such a way that underground storage becomes feasible, or a market
|
||
may develop for the waste coal and an outside party may purchase the waste coal.
|
||
|
||
Figure 3.2 _ Stage Storage Curves - Volume vs. Time
|
||
het og oe Gres
|
||
|
||
121510478.231 3.12 April 2012
|
||
|
||
|
||
|
||
|
||
»<
|
||
|
||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
In the event that such a scenario may arise, it would be prudent to be constructing the waste
|
||
piles and exposing the site in such a way that it requires minimal cost and effort to complete the
|
||
reclamation of the waste pile area.
|
||
|
||
3.2 SURFACE STORAGE - LOCAL REGION
|
||
|
||
As part of the potential identification of potential sites for the surface storage of waste the local
|
||
region was reviewed for abandoned surface open pits, large valley structures that could be
|
||
converted into a waste facility with limited construction for basin closure, or other large tracts of
|
||
land which would have less potential long term environmental impact than the Donkin Peninsula
|
||
area. The search was limited to within 75 to 100 km distance from the site for transportation
|
||
cost consideration. The search was also limited to existing transportation routes. There have
|
||
been no areas identified that are sufficient to handle the proposed volume of waste that will be
|
||
generated.
|
||
|
||
3.3. UNDERGROUND DISPOSAL - ON SITE
|
||
|
||
It is reasonable to consider the use of the mine workings to dispose of the waste stream from
|
||
the mining operation in so much as the waste stream is only approximately 12 percent of the
|
||
total volume mined. Even with very conservative bulking factors, the volume of the mined cavity
|
||
should always be much greater than the volume required for waste disposal,
|
||
|
||
In the case of the Donkin Mine, this potential method of waste disposal was discussed in the
|
||
preliminary assessment of options with Xstrata staff and it was determined that exploitation of
|
||
the underground areas for waste disposal is not compatible with the potential long term
|
||
exploitation of additional coal resources found at depth below the level presently planned for
|
||
production.
|
||
|
||
Based on this limitation, this option was not investigated further but should remain as a potential
|
||
waste disposal site should the mine and resource development plans change in the future. This
|
||
method (site) for waste disposal could be combined with the onsite surface disposal options in
|
||
later years and thus limit the amount of waste stored on surface as defined in this report.
|
||
|
||
3.4 UNDERGROUND DISPOSAL - LOCAL REGION
|
||
|
||
Due to the large volume of coal mined in the region during the last century, consideration has
|
||
been given to disposing of the coal waste back into these numerous abandoned underground
|
||
workings. The following sections address the practice of disposal in abandoned underground
|
||
workings throughout the world and the feasibility of this method for this particular project.
|
||
|
||
3.4.1 Brief Overview of Mine Waste Disposal in Abandoned Underground Workings
|
||
|
||
Alternatives to the surface disposal or sub-aqueous disposal of mine wastes have been
|
||
evaluated at mining operations worldwide. The practice of returning some or all of the waste
|
||
|
||
121510478.231 3.13 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
xstrata ‘Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
produced into worked-out underground voids, which is generally referred to as “backfilling” has
|
||
been adopted at many mine sites. Generally, the two primary advantages to this practice
|
||
compared to other more conventional surface based disposal options and sub-aqueous disposal
|
||
are that potential for subsidence of historic mine workings can be reduced and this option is
|
||
generally considered to cause less of an environmental impact compared to more conventional
|
||
practices.
|
||
|
||
While backfilling of abandoned mine workings might seem to be an obvious solution to mine
|
||
waste management, it is a relatively complex endeavor and operations require detailed
|
||
multidiscipline engineering to develop site specific processes and methods, compared to more
|
||
common practices of disposal of mine wastes into exhausted open pits, which is comparatively
|
||
a more straightforward backfilling operation.
|
||
|
||
‘The economic and practical feasibility of the use of backfilling techniques for underground mine
|
||
workings is largely site specific. Most commonly the process of backfilling for mine waste
|
||
management has been employed at metalifferous mines, with more limited application in coal
|
||
mines. More frequently, backfilling techniques are employed at the same mine site from where
|
||
the mine wastes originated, and little information is available on relocation of mine wastes to off-
|
||
site historic abandoned mine workings.
|
||
|
||
In effect, implementing a backfiling operation for disposal of mine wastes at an abandoned
|
||
underground mine site would require “re-opening” the mine for the purpose of backfilling rather
|
||
than extraction of ore. The associated infrastructure and methods of backfilling operations for
|
||
abandoned mines can be expected to vary, largely dependent on the physical/chemical make
|
||
up of the waste material and the condition of the receiving mine (e.g. storage capacity available,
|
||
mining methods used, condition of workings and supports, and many other factors). In general
|
||
terms, a conceptual operational system for disposal of mine wastes by backfilling of abandoned
|
||
historic mine workings would include the following main elements:
|
||
|
||
+ Mine Waste Transport System: A system for transporting the mine wastes from the source
|
||
mine to the proposed underground abandoned mine. This could entail utilizing existing
|
||
transportation infrastructure, but depending on physiographical and socio-economic factors,
|
||
could require development of new transportation infrastructure. Detailed assessment and
|
||
engineering and regulatory approvals may be required to assess the most feasible
|
||
transportation options.
|
||
|
||
Process Plant (e.g. Paste plant): Intended to process and provide additives to the mine
|
||
waste to achieve the desired physical properties for backfilling. The nature and complexity
|
||
of a paste plant would be highly influenced by the design intent(s) for backfilling (e.g.
|
||
Subsidence control, environmental control, etc.) and the physical characteristics of the mine
|
||
waste material
|
||
|
||
'* Conveyance System (e.g. Conveyor belt, pipeline): The system implemented to transport
|
||
the modified wastes to the underground workings for permanent storage.
|
||
|
||
121510478.231 344 April 2012
|
||
|
||
|
||
|
||
|
||
><
|
||
|
||
xstrata
|
||
coal ‘Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
The feasibility of backfiling of abandoned underground mines would also be highly influenced
|
||
by physiographical and socio-economic factors associated with the proposed receiving mine
|
||
site. For example, areas at and adjacent to historic mine sites may have become developed, or
|
||
current environmental regulations may identify features at historic mine sites that would
|
||
complicate permitting and approval processes associated with re-opening a mine to undertake a
|
||
backfilling operation,
|
||
|
||
3.4.2 Brief History of Coal Mining for the Sydney Coalfield
|
||
|
||
The Sydney Coalfield contains the largest coal reserves in eastern Canada, and extends
|
||
Northwesterly from Cape Morien to Cape Dauphin, over a distance of about 36 miles. There
|
||
are twelve (12) major seams in the Sydney Coalfield, varying in thickness from three (3) to
|
||
seven (7) feet (with localized areas of around 10 ft), The legacy of coal mining in the Cape
|
||
Breton Regional municipality is considerable, and has been concentrated primarily in areas of
|
||
Glace Bay, Morien, New Waterford, and Sydney Mines
|
||
|
||
The Sydney Coalfield lies close to the Atlantic Ocean coastline and a large percentage of the
|
||
fields extend under the ocean. As a result, a considerable portion of the historic underground
|
||
mining was sub-marine. Generally speaking, there have been two main methods of extracting
|
||
coal employed in historic mining operations. The first, and most generally used in the earlier
|
||
years of coal mining, was the "toom/bord and pillar” method. The second primary method of
|
||
extraction was the "long wall" method, which was used in the more recent mining endeavors in
|
||
the Sydney Coalfield.
|
||
|
||
3.4.3 Summary of Coal Mine Productions for Sydney Coalfield
|
||
|
||
For the period between 1863 to 1976, Nova Scotia Department of Natural Resources (formerly
|
||
Nova Scotia Department of Mines) reported coal production totals for the Sydney Coalfield as
|
||
being 258,506,325 tons, which included nearly 100 individual coal mines throughout five (5)
|
||
main districts. These districts and associated reported coal production totals between this
|
||
period are summarized in Table 3.1, below.
|
||
|
||
Table 3.1__ Sydney Coalfield Coal Production Volumes (1863-1976)
|
||
|
||
Production Range of | Coal Production
|
||
|
||
Individual Mines In| Total for District
|
||
District (tons) (tons)
|
||
|
||
Port Morien District 555 t0 2,341,056
|
||
|
||
| Number Reported
|
||
Organized Mines"
|
||
|
||
Coal Mining District
|
||
|
||
Glace Bay District 2,380 to 86,364,095 133,564
|
||
‘Sydney Mines District 293 to 42,868,466 ‘44,994,987
|
||
‘New Waterford District 137 to 30,951,424 168,165,317
|
||
‘New Campbellton District ‘51 to 174,426 174,977
|
||
|
||
Total Reported Production Tons (1863-1976) 258,506,325
|
||
|
||
Noles
|
||
(1) The number of reported mine sites does not include lic “bootleg” mines, which was @ common occurence in the Sydney
|
||
Cozlfeld, and reportedly Included substantial addtional coal producton over that noted above.
|
||
|
||
121510478,231 3.15 April 2012
|
||
|
||
|
||
|
||
|
||
»<
|
||
|
||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
3.4.4 Option Evaluation Framework
|
||
|
||
For the purpose of this assignment, a high level evaluation has been undertaken to assess a
|
||
disposal option of backfiling of abandoned mine workings in the Sydney Coalfield for the
|
||
management of coal wastes generated from the future Donkin Mine. A comprehensive
|
||
assessment of specific receiving abandoned mines for feasibility of underground disposal is
|
||
beyond the scope of this assignment, and the intent is to identify the general viability of this
|
||
mine waste management practice for management of the generally 23 million tonnes of coal
|
||
waste estimated to be generated over the forecasted operating period for the Donkin Mine.
|
||
|
||
In this context, only a small number of abandoned mine sites have been considered as part of
|
||
this option evaluation. Further, mine sites considered have been limited to known abandoned
|
||
mine sites that are closest geographical relation to Donkin Mine site and with reported largest
|
||
coal production tonnages, as these two characteristics are considered to be two of the primary
|
||
features of a potential receiving mine site so as to be considered feasible and economical for a
|
||
backfilling option. Mine sites considered for this evaluation are summarized in Table 3.3, and
|
||
have been grouped into three main categories based on geographical location of the former
|
||
mine in relation to Donkin. General locations of these Groupings and associated abandoned
|
||
mine sites are depicted on Figure 3.2. Figure 3.3 provides a depiction of the same general
|
||
study area, but identifies general areas and extents where historic underground mine workings
|
||
are known to be present. It should be noted that for Groups 1 and 3, there has been
|
||
considerable sub-marine coal mining activity, and the extent of workings shown in Figure 3.3
|
||
extends a considerable distance northward below the Atlantic Ocean.
|
||
|
||
It should be noted that there are several other abandoned mines in the same general area of
|
||
those identified herein, however as previously stated, this evaluation has been limited to historic
|
||
mine sites noted as having larger and significant historic productions.
|
||
|
||
Table 3.2___ Summary of Mine Sites Considered
|
||
|
||
NSDNR Reported
|
||
|
||
Grouping | Mine ee ‘Abandoned Mine Sites Beene
|
||
ne city Volume (tons)
|
||
Donkin Dominion 6 Coliery 3.162876 |
|
||
1 Glace Bay Donkin ‘Schooner Pond/Acadia Mine 16,541
|
||
Port Caledonia Clyde Mine 238,310
|
||
Combined Production for Group 1=| 3,419,727
|
||
Port Morien Blockhouse Mine 1,168,986
|
||
|__Pont More eM
|
||
[orien Gowrie Mine 1,930,837
|
||
2 Morien ae
|
||
[Birch Grove Dominion 21/22 Colliers 3,626,056
|
||
Broughton 4 Star / Broughton Mine 1,599,990
|
||
Combined Production for Group2=| 8,326,769
|
||
|
||
121510478.231 3.16 April 2012
|
||
|
||
|
||
|
||
|
||
»<
|
||
|
||
fata
|
||
nd Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Table 3.2___ Summary of Mine Sites Con:
|
||
|
||
NSDNR Reported.
|
||
|
||
Grouping | Mine | Township naa Si Production
|
||
i i Volume (tons)
|
||
|
||
Caledonia Dominion 24 Caliery 780,01
|
||
|
||
Steeles Hi Dominion 11 Caley 7241887
|
||
|
||
Caledonia Dominion 4 Coley 991081
|
||
|
||
Glace Bay | — —-
|
||
Steing Dominion 2 and 20 Colleres 3779882
|
||
New Aberdeen | Dominion 18 and 26 Colles
|
||
Reserve Mines | Dominion 5 and 10 Collies 306,940
|
||
Combined Production for Groupa=| 115,994,842
|
||
|
||
121510478.231 347 April 2012
|
||
|
||
|
||
|
||
|
||
oC
|
||
|
||
xstfata Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE.
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Figure 3.3 General Location of Abandoned Mine Sites Relative to Donkin
|
||
|
||
ine (Source: Google Maps)
|
||
|
||
DONKIN
|
||
MINE
|
||
|
||
Broughton/4 Star
|
||
|
||
121510478.231 3.18 2012
|
||
|
||
|
||
|
||
|
||
|
||
a
|
||
|
||
xstrata
|
||
|
||
coal
|
||
|
||
Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Figure 3.4 General Areas of Historic Mine Workings (Source: NSDNR GIS)
|
||
|
||
LEGEND
|
||
coal Workings
|
||
|
||
&
|
||
|
||
121810478,231 3.19
|
||
|
||
April 2012
|
||
|
||
\GROUP 1
|
||
|
||
|
||
|
||
|
||
|
||
D<
|
||
|
||
rata
|
||
cs ‘Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED.
|
||
|
||
3.4.5 Discussion of Findings
|
||
|
||
For assessing the suitability and feasibility of backfilling abandoned mine sites as a mine waste
|
||
management option, there are numerous physical, physiographical, social, environmental,
|
||
economic, and other considerations that would have to be evaluated. Considering the purpose
|
||
and scope of this evaluation, the option evaluation will be limited to what are considered to be
|
||
Primary Site Considerations, as listed below:
|
||
|
||
* Potential storage capacity of the receiving mine;
|
||
* Transportation of mine waste from Donkin to receiving mine;
|
||
* Condition of receiving mine workings; and
|
||
|
||
* Potential constraints/sensitivities related to physiographic and/or existing land
|
||
development/usage at receiving mine.
|
||
|
||
While economic considerations are fundamentally important to the evaluation of any option, they
|
||
have not been specifically included as a Primary Considerations at this level of evaluation. The
|
||
Primary Considerations identified above may exclude the feasibility of developing a site for
|
||
backfiling, regardless of the associated costs. Further, from an order of magnitude costing
|
||
level, the infrastructure and development at any site would generally be expected to include the
|
||
same types of infrastructure and methods, with similar cost implications per site. The most
|
||
significant factors expected to influence variations in site specific costs between abandoned
|
||
mine sites are associated with the transporting the reject material from the Donkin site to the
|
||
receiving site and the existing conditions of the mine workings at the receiving site, which are
|
||
included in the Primary Considerations identified above.
|
||
|
||
Using readily available public reference sources, cut-sheets have been developed for the mine
|
||
sites considered as part of this evaluation. Cut-sheets are included in Appendix I, along with
|
||
Figures depicting the general locations of sites within each grouping.
|
||
|
||
Table 3.4 provides a brief summary of mine features/characteristics identified for the historic
|
||
mine sites considered, as it pertains to the primary considerations identified above. It should be
|
||
noted that these characteristics have been evaluated on a high level and based on limited site
|
||
specific information that was attainable from readily available public sources. More detailed
|
||
assessments on a site specific basis would be required to properly identify existing conditions
|
||
and to thoroughly characterize feasibility of a specific mine site for backfilling with mine wastes.
|
||
|
||
Considering the findings for each of the abandoned mine sites, the following sections discuss
|
||
the potential receiving sites as evaluated against the Primary Considerations identified above.
|
||
Table 3.5 provides a comparison of identified significant pros/cons and strengths/limitations
|
||
identified from this evaluation of Primary Considerations.
|
||
|
||
121510478.231 3.20 April 2012
|
||
|
||
|
||
|
||
|
||
xatrata st
|
||
{ONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS -DONMN MINE
|
||
|
||
Table 2.3 General Characterization Summary of Abandoned Mine Sites
|
||
|
||
‘Cae
|
||
|
||
sarstosraaat sz ‘2012
|
||
|
||
|
||
|
||
|
||
xstrata
|
||
|
||
coal Stantec
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Table 3.4 __ Evaluation of Mine Site Characteristics Against Primary Considerations for Redevelopment
|
||
|
||
Primary
|
||
Consideration
|
||
|
||
Primary ProsiStrengths
|
||
|
||
‘© The Dominion 6 mine is the only site within this
|
||
‘group expected to have any significant storage
|
||
Capacity to accept coal mine wastes. Its
|
||
possible that the Dominion 6 Mine may be
|
||
‘connected underground to the Group 3 mines
|
||
|
||
not provide the requirad storage
|
||
it tobe considered bacling as
|
||
a primary option for managemer
|
||
coal wastes from the Donkin Mine
|
||
+ The mine sites in this group are not
|
||
1 likely connected underground based on
|
||
production volumes and coal seams
|
||
mined,
|
||
The actual capacity of any mine is
|
||
|
||
Dominion 6 Mine |
|
||
|
||
are
|
||
1e required storage capacity
|
||
‘may be attained with re-opening a single mine
|
||
at Dominion 6.
|
||
|
||
Potential Storage
|
||
Capacity =
|
||
|
||
vide sufficient capacity for backfilling
|
||
‘make this group an option to
|
||
consider backflling as a primary waste
|
||
‘management option for Donkin, and |
|
||
2 would require development of mine | * None Identified. None Identified
|
||
sites in other areasicistricts,
|
||
‘©The actual capacity of any mine
|
||
largely uncertain, as
|
||
dependent on the exi
|
||
the underground workings.
|
||
|
||
121510478.231 3.22 April 2012
|
||
|
||
|
||
|
||
|
||
B<
|
||
|
||
xstre
|
||
saa sone
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Table 3.4
|
||
|
||
Primary Mine
|
||
Consideration | Grou
|
||
|
||
This Group offers the greates
|
||
capacity.
|
||
‘On an individual mine basis,
|
||
|
||
forecast
|
||
However, considering that mines in this group
|
||
|
||
| s reve erocerg marines n 8G? | 4 sas conser
|
||
|
|
||
|
||
this Group
|
||
claro werkiene ‘group would provide the greatest potential for
|
||
|
||
available capacity
|
||
|
||
= _ Existing transportation rout
|
||
‘developed parts of Donkin
|
||
1 | Damage/deterioration to e»
|
||
roadways and associated .
|
||
| maintenance/repair costs.
|
||
‘Transportation costs expected tobe | less developed,
|
||
Transportation of Mine | much higher in comparison to Group 1 and comparatively expected to generate the
|
||
Wastes | sites, given increased distance from the | _least public adversity
|
||
| Donkin Site.
|
||
| 2 | Some residential developments along
|
||
|
||
All Sites Considered in
|
||
this Group
|
||
|
||
+ Would seem to have least constraints for option
|
||
|
||
|” of developing new transportation infrastructure,
|
||
|
||
existing rout
|
||
+ Damageldeterioration to existing
|
||
|
||
inimize transportation impacts along public
|
||
roadways.
|
||
|
||
i maintenance/repair costs
|
||
|
||
121510478.231 3.23 April 2012
|
||
|
||
|
||
|
||
|
||
><
|
||
|
||
xstrata
|
||
‘coal
|
||
|
||
Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Table 3.4
|
||
|
||
Primary Mine
|
||
|
||
Consideration | Group
|
||
|
||
"Transportation costs expected to be
|
||
‘much higher in comparison to Group 1
|
||
and Group 3 sites, given increased
|
||
distance from the Donkin Site.
|
||
Significant commercial anc
|
||
‘development along existing
|
||
transportation infrastructure.
|
||
Existing developments expected to
|
||
‘provide constraints to considering
|
||
‘options for development of new
|
||
transportation infrastructure.
|
||
|
||
None identified. None Identified
|
||
|
||
Condition of Mine | 1,2,
|
||
Workings and 3
|
||
|
||
Existing condition of workings unknown.
|
||
Based on age of mines, potential
|
||
significant constraints with condition of
|
||
mine supports and possible cave-ins
|
||
|
||
Considering the mining methods employed,
|
||
|
||
None Identi
|
||
|
||
management option. However, consideration |
|
||
of this as a strength is superseded by the
|
||
|
||
uncertainty of the actual conditions of mine
|
||
workings.
|
||
|
||
Existing Land
|
||
Development/Usage
|
||
Constraints
|
||
|
||
Considerable residential development
|
||
at and around areas of former mine
|
||
|
||
For the Schooner Pond/Acadia mine, areas are
|
||
largely undeveloped with some minor
|
||
residential development in adjacent areas,
|
||
|
||
‘Schooner PondiAcadia
|
||
Mine
|
||
|
||
‘Dominion 21/22 Colliers situated
|
||
|
||
‘adjacent to the south of the community
|
||
‘ch Grove and considerable
|
||
|
||
ntial development in this area.
|
||
|
||
Blockhouse, Gowrie and Broughton/4 Star
|
||
‘mines are in largely undeveloped areas, with
|
||
relatively minor residential development in
|
||
surrounding areas.
|
||
|
||
Blockhouse Mine
|
||
Gowrie Mine
|
||
Broughton 4/Star Mines
|
||
|
||
121510478,231
|
||
|
||
3.24
|
||
|
||
April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xstrata
|
||
coal
|
||
|
||
Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Table 3.4
|
||
|
||
Evaluation of Mine Site Characteristics Against Primary Considerations for Redevelopment
|
||
|
||
Dominion 18/26
|
||
Dominion 4
|
||
|
||
Detailed assessment would be required
|
||
to evaluate and identify potential
|
||
environmental receptors.
|
||
|
||
Mine water dewatering expected to be
|
||
associated
|
||
|
||
Further Assessment
|
||
Would be Required to
|
||
| Identify Sites,
|
||
|
||
environmental impact than more conventional
|
||
surface management options.
|
||
|
||
121510478.231
|
||
|
||
3.25 April 2012
|
||
|
||
|
||
|
||
|
||
xstrata
|
||
|
||
coal Stantec
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
3.4.6 Potential Storage Capacity
|
||
|
||
Based solely on reported coal production volumes, collective reported production volumes for
|
||
historic mine sites would certainly suggest that sufficient capacity is available within the mined
|
||
areas of the Sydney Coalfield to accommodate the forecasted volumes of coal waste expected
|
||
to be generated over the operating life of the Donkin Mine. However, on an individual mine site
|
||
basis, there are no individual mines sites within the groups considered that would be expected
|
||
to solely accommodate the expected volume of mine waste. There is potential that some of the
|
||
mine sites are connected, and it may be possible to utilize underground connections to access
|
||
multiple mine sites, with a single historic mine site developed with mine waste processing and
|
||
conveyance systems. However, considering the uncertainty of conditions of workings for
|
||
historic mines, it is considered most likely that multiple former mine sites would have to be
|
||
utilized to make a backfilling option feasible.
|
||
|
||
1 Wastes
|
||
|
||
3.4.7 Transportation of Mil
|
||
|
||
The only existing transportation infrastructure identified that could be utilized for transport of
|
||
mine wastes from the Donkin Site to the potential receiving abandoned mine sites is via public
|
||
roadways, which are under provincial and municipal jurisdictions. While existing transportation
|
||
infrastructure is in place for a road based transportation option, there are considerable potential
|
||
limitations with respect to community impacts (public concerns of noise and increased traffic,
|
||
safety risks of increased haulage traffic, deterioration of primary roadways, efc.) and
|
||
environmental impacts. Group 3 sites are expected to have the most limitations given the
|
||
considerable land development around the mine sites. Construction of new and less disruptive
|
||
transportation infrastructure may have to be considered, which may be physically or cost
|
||
Prohibitive depending on the distance from the Donkin Site, physiographical constrains, and/or
|
||
existing developments along available routes.
|
||
|
||
3.4.8 Expected Condition of Mine Workings
|
||
|
||
For all the abandoned mine sites considered, information is not available to characterize the
|
||
existing condition of the mine workings. However, some general statements regarding potential
|
||
conditions of historic mine workings based largely on the age of the mines and mining methods
|
||
identified are provided below:
|
||
|
||
+ Based on the age of the mines, itis likely that all sites are currently flooded to equilibrium, or
|
||
approaching equilibrium. It is considered likely that redevelopment of any abandoned mine
|
||
site will require substantial dewatering efforts, posing potential constraints associated with
|
||
regulatory approvals and environmental controls.
|
||
|
||
‘* As previously mentioned, itis likely that multiple mine sites may be connected underground.
|
||
This is especially true of the Group 3 mine sites.
|
||
|
||
‘* Considering the age of the mines, the condition of the mine supports are expected to be
|
||
deteriorated and considerable sections of caved workings may have occurred.
|
||
|
||
121510478.231 3.26 April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xstr
|
||
gia Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
* Considering the mining methods employed, considerable volumes of coal seams left in-situ
|
||
would remain. This may offer a positive consideration for backfilling, as conceivably it may
|
||
be possible to recover coal as part of backfilling operations.
|
||
|
||
3.4.9 Potential Constraints Related to Existing Land Development/Usage and/or
|
||
Sensitivities
|
||
|
||
To undertake a backfiling option for management of mine wastes, effectively this would entail
|
||
re-opening former mines. Since cessation of the historic mining operations, in some cases
|
||
considerable development has occurred at and adjacent to the former mine sites. Associated
|
||
current land usage could provide significant constraints with respect to considerations of re-
|
||
opening a mine for the purpose of backfiling. Such re-development constraints are considered
|
||
most prominent for Group 3, and to a lesser extent for Group 1. The Group 2 mines sites are
|
||
situated in areas of least development and expected to have least constraints associated with
|
||
current land development.
|
||
|
||
The sites by the defined grouping are illustrated in Figures 3.4, 3.5, and 3.6.
|
||
|
||
Potential environmental or regulatory constraints are difficult to define at this level of
|
||
assessment, and would require more detailed investigation and assessment. However, some
|
||
general comments are provided below with respect to environmental approvals and
|
||
considerations:
|
||
|
||
‘+ Backfling of mine wastes underground is generally considered of lower risk than more
|
||
conventional surface management options
|
||
|
||
* Itis expected that multiple abandoned mine sites would have to be considered for backfilling
|
||
to be feasible, it is expected that unique environmental assessments and approvals would
|
||
be required for each abandoned mine site.
|
||
|
||
* As previously discussed, re-opening abandoned mine sites for backfilling would be expected
|
||
to require dewatering of mine workings. Mine water management, control, and possibly
|
||
treatment would have to be considered which would be expected to have significant cost
|
||
and environmental regulatory implications. Further, if multiple sites are required to be
|
||
developed for backfiling, dewatering may have to be employed at multiple sites (excepting
|
||
possible interconnected mines, which potentially may be dewatered from a single location).
|
||
|
||
121510478.231 3.27 April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xstrata
|
||
|
||
coal
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Stantec
|
||
|
||
Figure 3.5 Group 1 Historical Coal Mine Sites
|
||
|
||
Clyde Mine
|
||
Cut Sheet 3
|
||
|
||
°
|
||
°
|
||
|
||
121610478.231 3.28
|
||
|
||
Dominion 6 Mine
|
||
|
||
Cut Sheet 2
|
||
|
||
Schooner Pond/Acadia Mines
|
||
|
||
°
|
||
|
||
April 2012
|
||
|
||
Cut Sheet 1
|
||
|
||
DONKIN.,
|
||
|
||
AMINE :
|
||
|
||
|
||
|
||
|
||
|
||
oC
|
||
|
||
xstrata
|
||
coal Stantec
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
Figure 3.6 Group 2 Historical Coal Mine Sites
|
||
|
||
DONKIN
|
||
MINE
|
||
|
||
9 *Blockhouse Mine
|
||
|
||
Dominion 21/22 Mihes @ Cut Sheet 4
|
||
Cut Sheet 6» A
|
||
|
||
Gowrie Mine
|
||
Cut Sheet 5
|
||
|
||
- Broughton/4 Star Mines
|
||
|
||
4121510478.231 3.29 April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
sg ste
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS REVIEWED
|
||
|
||
\ure 3.7 Group 3 Historical Coal Mine Sites
|
||
|
||
& » .Dominion 1B/26 Mines
|
||
Cut Sheet 12
|
||
|
||
-Dominion 2/20 Mines
|
||
Cut Sheet 11
|
||
|
||
* gDominion 4 Mine
|
||
°” Cut Sheet 10
|
||
|
||
Boning 15/10 * os
|
||
|
||
Dominion 24 Mine
|
||
|
||
Deniion 11 Mine
|
||
Cut Sheet’ 8” Cut Sheet 9
|
||
|
||
121510478.231 3.30 April 2012
|
||
|
||
|
||
|
||
|
||
xstrata
|
||
|
||
Coal ‘Stantec
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS,
|
||
|
||
3.4.10 Summary of Findings and Conclu:
|
||
|
||
Considering the comparison of historic mine sites considered as part of this option evaluation to
|
||
the Primary Considerations discussed above, the following general conclusions are provided:
|
||
|
||
+ The available information would indicate that abandoned mine sites in the Sydney Coalfield
|
||
could accommodate the expected volumes of mine wastes expected to be generated from
|
||
the Donkin Mine. However, itis realistically expected that multiple sites would have to be re-
|
||
developed to support a backfiling option.
|
||
|
||
+ In consideration of all the primary considerations for re-opening, there is no individual Group
|
||
‘or mine site that would not be expected to provide significant constraint(s) with respect to re-
|
||
development for the purpose of backfilling. For example, if considering all the primary
|
||
considerations evaluated, former mine sites in Group 2 and the Schooner Pond/Acadia Mine
|
||
in Group 1 would appear to be best suited to minimize public concerns and associated
|
||
regulatory approvals, however, these sites have the least available capacity for storage and
|
||
would require more sites to be considered,
|
||
|
||
‘+ The uncertainty of the condition of existing mine workings is a paramount consideration, as
|
||
it could negate all the potential positive attributes of a particular mine site as far as feasibility
|
||
for re-development. Considerable assessment and investigation in this capacity alone is
|
||
expected to be complex and likely cost prohibitive.
|
||
|
||
In conclusion, consideration of backfiling of abandoned mine workings as a management
|
||
practice for mine wastes generated from the Donkin site is considered theoretically possible, but
|
||
highly impractical and improbable considering known constraints, uncertainties regarding the
|
||
condition of historic mine workings, and the level of effort required to evaluate for further
|
||
consideration.
|
||
|
||
3.5 OCEAN DISPOSAL
|
||
|
||
Ocean disposal of coal waste would require specific engineering considerations and would
|
||
increase the regulatory burden for the Project and uncertainty of approval. Adverse ecological
|
||
and socio-economic effects would require special consideration and would require specific
|
||
consultation efforts and likely result in additional compensation requirements. This review of
|
||
ocean disposal of the defined CHPP waste stream(s) relies on the previous work compiled by
|
||
XCDM and presented in their February 2011 report - Coal Waste Ocean Disposal Investigation
|
||
(A Concept Study).
|
||
|
||
As indicated on page 65 of the Concept Study, under the heading Deep Sea Tailings Placement
|
||
.., the coal waste material will likely need to be altered for transport and deposition and
|
||
therefore would be best characterized as a slurry.
|
||
|
||
421510478.231 3.31 April 2012
|
||
|
||
|
||
|
||
|
||
De
|
||
|
||
sue ta st
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS,
|
||
|
||
Engineering considerations to be factored into Project design, should ocean disposal of this
|
||
waste be selected as a preferred alternative, include:
|
||
|
||
* Removal of air bubbles from the slurry to prevent formation of a surface plume: This
|
||
may require de-aeration and/or thickening of tailings.
|
||
|
||
* Mixing of tailings with seawater: Seawater can be used to coagulate the slurry and
|
||
provide a dilution factor prior to marine discharge.
|
||
|
||
+ Discharge pipe engineering: Special consideration must be taken to select an appropriate
|
||
pipe entry point for discharge (¢.g., shoreline/shallow water, deep sea tailings disposal).
|
||
The pipe must also be designed using adequate material to withstand waves and currents
|
||
and avoid pipe blockage or breakage. Slope of the pipe and rate of discharge can affect
|
||
blockage.
|
||
|
||
‘© Receiving environment: The receiving marine environment will affect the flow and
|
||
dispersion of the slurry. Water currents and sediment grain size will influence the deposition
|
||
and migration of the slurry. Modeling would be required to predict the extent of slurry
|
||
deposition. This information would be required to predict ecological and socio-economic
|
||
effects for permitting, consultation, and compensation.
|
||
|
||
Designation of an appropriate disposal site would be required in consultation with Environment
|
||
Canada, Fisheries and Oceans Canada (DFO) as well as fishers and representatives of the
|
||
kmaq Community. Depending on the distance to an acceptable candidate site, this may
|
||
have engineering, logistical, and financial implications for the Project, particularly ifthe site is far
|
||
removed from the Project and would require barging of waste material
|
||
|
||
Marine disposal of coal tailings would be considered “disposal at sea and would require
|
||
authorization under Section 127 of the Canadian Environmental Protection Act (CEPA). Under
|
||
this authorization process, only certain materials are eligible for authorized disposal, including:
|
||
dredged waste; fish waste; uncontaminated organic matter of natural origin; inert, inorganic
|
||
geological matter; bulky substances; and vessels. In this case, the pipeline tailings would need
|
||
to be demonstrated to be inert geological matter.
|
||
|
||
As part of the permitting process, the Proponent would be required to demonstrate there is no
|
||
Viable alternative to the ocean disposal of waste and that the material will not pose a risk to the
|
||
marine environment. This requirement would prove difficult as a feasible alternative (i.e., land
|
||
disposal) exists as demonstrated elsewhere in this report.
|
||
|
||
Testing and characterization of the material to be disposed at sea, as well as characterization of
|
||
the proposed disposal site would be required. Guidance can be obtained from Environment
|
||
|
||
121510478.231 3.32 April 2012
|
||
|
||
|
||
|
||
|
||
xstrata
|
||
|
||
coal Stantec
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS
|
||
|
||
Canada on requirements for selection and characterization of a disposal site, but generally this
|
||
includes, at a minimum, a description of bathymetry, currents, water depth, and benthic habitat
|
||
at the proposed site. This information is gathered through a dedicated marine survey. The
|
||
permit process requires public notification and consultation with users/managers of marine
|
||
resource area. The length of time to obtain this permit would likely be in the range of two to four
|
||
months.
|
||
|
||
There is also a fee associated with the permit which, based on the estimated quantity of coal
|
||
waste for disposal, could be approximately $10.9 million for the LOM based on 23,200,000 m?
|
||
for disposal (based on values from ACDM, 2011). This does not include any operational costs
|
||
that may be associated with installing a discharge system and/or hauling waste by barge to the
|
||
disposal site, nor does it include compensation or monitoring costs.
|
||
|
||
Disposal at sea would also require an authorization for fish habitat alteration, disruption, and
|
||
destruction (HADD) under the Fisheries Act. This authorization requires quantification of the
|
||
extent of habitat effects and habitat compensation to ensure no net loss of fish habitat. Ocean
|
||
disposal of coal waste (particularly given the low specific gravity of the material) would inundate
|
||
the seafloor near the discharge point resulting in localized mortality of marine benthic species
|
||
and substantially affecting the productivity of the benthic environment in the area of deposition.
|
||
|
||
Other effects would include turbidity and sedimentation as well as changes to substrate type
|
||
and chemistry. Mitigation of these effects will require extensive habitat compensation programs
|
||
to ensure no net loss of the productive capacity of fish habitat as required by DFO Policy. Other
|
||
adverse environmental and operational effects could also be expected from the barging of coal
|
||
waste such as increased air emissions from marine transportation as well as down time
|
||
associated with inclement weather.
|
||
|
||
There is also a possibility that authorization may be required under the Navigable Waters
|
||
Protection Act (NWPA), depending on the discharge location and infrastructure that may be
|
||
required (e.g., discharge pipe).
|
||
|
||
Disposal at Sea, HADD, and NWPA authorizations would trigger environmental assessment
|
||
under the Canadian Environmental Assessment Act (CEAA). The Donkin Mine Coking Coal
|
||
Export Project is currently under a CEAA process, although disposal at sea would increase the
|
||
permitting burden.
|
||
|
||
The marine environment around the peninsula has been characterized as productive lobster
|
||
habitat and active fishing grounds for commercial and Mikmaq fisheries. Effects on fish habitat
|
||
could result in reduced resource availability (e.g. fish mortality and/or dispersion of stocks),
|
||
decreased access to fishing area, and interference with fishing gear and/or navigation,
|
||
depending on the location of the disposal site. These effects could result in reduced net income
|
||
for commercial fishermen and affect Mi'kmag fisheries. These effects would add to the other
|
||
|
||
121510478.231 3.33, April 2012
|
||
|
||
|
||
|
||
|
||
p<
|
||
|
||
xstrata Stantec
|
||
|
||
coal
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
POTENTIAL OPTIONS,
|
||
|
||
predicted effects on marine habitats and the fishery associated with the construction of a marine
|
||
load-out facility, and transshipment mooring. Disposal at sea will raise serious concerns among
|
||
fishers in the Project/disposal area and could require financial compensation to address these
|
||
effects.
|
||
|
||
In summary, disposal at sea will require considerable planning and consultation and, in order to
|
||
get regulatory approval, the application would require demonstration that no other viable
|
||
alternative exists for disposal. Given there is a technically and economically feasible alternative
|
||
to ocean disposal where environmental effects can be managed (i.e., land disposal) there is a
|
||
substantial risk that large scale ocean disposal of Donkin coal waste would not be approved.
|
||
|
||
121510478.231 3.34 April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
xstrata
|
||
coal
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
4.0 Conclusions
|
||
|
||
Several options were reviewed for the disposal of the potential 20 million cubic metres of coal
|
||
process rejects involved with the Donkin Project. This large volume of rejects, and the site
|
||
location, requires the use of multiple sites when considering conventional methods, which
|
||
unavoidably adds complications, cost, and additional land use. It follows that the direct
|
||
comparison to other case histories must be carefully reviewed to ensure that local limitations are
|
||
properly considered.
|
||
|
||
In the case of ocean dumping, the total volume and the nature of the rejects make it highly
|
||
unlikely that a successful application and dump site could be obtained.
|
||
|
||
Underground disposal on site is limited by current XCDM mining and long term development
|
||
plans, but remains an available option if such plans for development change in the future,
|
||
|
||
Regional underground storage in abandoned workings required development of several sites
|
||
and was found to be technically possible but not practical.
|
||
|
||
Surface storage on the XCDM property on the Donkin Peninsula is a viable option for surface
|
||
storage of production waste (CHPP) materials.
|
||
|
||
Four options for surface storage were reviewed and the preferred option (# 4) involved the stage
|
||
construction of the storage facilities on site. This process of stage (or phased) construction has
|
||
several advantages that are outlined in the document.
|
||
|
||
Peter E. Pheeney, M.Sc.E., P.Eng. Mark MacDonald, P.Eng.
|
||
|
||
Senior Geotechnical Engineer, Project Manager Associate, Geotechnical Engineer
|
||
Tel: (506) 457-3241 Phone: (902) 566-2866
|
||
|
||
Fax: (506) 452-0112 Fax: (902) 566-2004
|
||
peter.pheeney@stantec.com Mark.MacDonald@stantec.com
|
||
|
||
121510478.231 44 April 2012
|
||
|
||
|
||
|
||
|
||
OC
|
||
|
||
x
|
||
sia ta st
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
5.0 References
|
||
|
||
Cape Breton Miners Museum Website: http://www.minersmuseum.com/
|
||
|
||
CBCL Limited. (October 2008). Donkin Underground Exploration Project, Environmental
|
||
Assessment.
|
||
|
||
CBCL Limited. (January 2012). Marine Transport Option. Additional Engineering Requirements
|
||
for Input to Environmental Impact Study.
|
||
|
||
Colaizzi, Gary J. et al. (1981): United States Department of Interior Beareau of Mines,
|
||
Information circular 8846: Pumped-Slurry Backfilng of Abandoned Coal Mine Workings
|
||
for Subsidence Control at Rock Springs, Wyo.: US Government Printing Office,
|
||
Washington DC
|
||
|
||
Ellerbok, G. W. (2000, May 28). The Louis Frost Notes 1685-1962. Retrieved December 2011,
|
||
from Mining History Nova Scotia: http://www. mininghistory.ns.caltfrost/lfintro.htm
|
||
|
||
Geological Survey of Canada. (1873). Report of Progress for 1872-73. Montreal: Dawson
|
||
Brothers.
|
||
|
||
Grice, Tony. (1998), Underground Mining with Backfill. Paper Presented at The 2nd Annual
|
||
‘Summit - Mine Tailings Disposal Systems, Brisbane, 24-25 November 1998.
|
||
|
||
Gusek, James, Masloff, Brian and Fodor, John, (2012). Engineered Pumpable pHoam"™ : A
|
||
new innovative Method for Mitigating ARD, SME, Seattle Washington.
|
||
|
||
Hunt, Roy E. (1986). Geotechnical Engineering Techniques and Practices. McGraw-Hill Book
|
||
Company.
|
||
|
||
ITRC (Interstate Technology & Regulatory Council). 2010. Backfilling and Subaqueous
|
||
Disposal. Washington, D.C.: Interstate Technology & Regulatory Council, Mining Waste
|
||
Team. www.itreweb.org,
|
||
|
||
Nova Scotia Department of Mines. (1978). A History of Coal in Nova Scotia - Information Series
|
||
No. 2.
|
||
|
||
Nova Scotia Department of Natural Resources. (2011). Geology Maps and Databases.
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Retrieved December 2011, from ArcIMS Viewer:
|
||
fitp://gis4.natr. gov.ns.ca/website/nsgeomap/viewer.htm
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Nova Scotia Environment. (2009). Guide for Surface Coal Mine Reclamation Plans.
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‘Sedgman (May 2010). Donkin Project, CHPP Pre-Feasibility Study Report.
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121510478.231 54 April 2012
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OC
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xstrata Stantec
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coal
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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
REFERENCES
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||
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||
Shea, J. (2008, April 22). Innovative Mine Water Management Techniques for Submarine Coal
|
||
Mines of the Sydney Coalfield, Nova Scotia. Morgantown, West Virginia.
|
||
|
||
Stantec. (July 2011). Project Description: Environmental Assessment for Donkin Export Coking
|
||
Coal Project.
|
||
|
||
Stantec. (March 2012). Project Description: Draft Environmental Impact Statement for the
|
||
Donkin Export Coking Coal Project.
|
||
|
||
Ward, Colin R. et al. (August 2006): Cooperative Research Centre for Coal in Sustainable
|
||
Development, Use of Coal Ash in Mine Backfill and Related Applications: Research
|
||
Report 62: QCAT Technology Transfer Centre
|
||
|
||
Xstrata. (June 2006). CRM Surface Spontaneous Combustion Management Plan 2006.
|
||
|
||
Xstrata Coal Donkin Management (XCDM). (February 2011). Coal Waste Ocean Disposal
|
||
Investigation (A Concept Study),
|
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121510478.231 52 April 2012
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p<
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xstrata
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||
coal
|
||
|
||
CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
|
||
|
||
APPENDIX |
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|
||
Donkin Peninsula Surface Deposition Options
|
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|
||
TST SHES RONG HOS VINEE =a]
|
||
|
||
ps ‘eon no aaee anavanowod sovans onus
|
||
|
||
(ZNoUdO) SFTId TWSOdSIO 31S¥M Saar RTET ETT
|
||
|
||
|
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|
||
|
||
|
||
WASTE DISPOSAL PILES (OPTION 3)
|
||
|
||
|
||
|
||
|
||
|
||
‘SEENOTE 14 NOTE:
|
||
|
||
Paceoseo Ror.
|
||
WOLONG POND LOCATION
|
||
|
||
xX
|
||
|
||
xstrata
|
||
|
||
= WASTE DISPOSAL PILES (OPTION 4) a eo
|
||
oe on ps Le
|
||
int STRATA COAL DONRIN MONAGEMENT LIMITED. Cx ‘Stantec |
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