nm3clol-public/Amys_Drop_Box/Coal Waste Study/README.md

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title: Coal Waste Study
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  - Amys_Drop_Box
docDate: 2012-04
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xstrata

coal

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Stantec

Concept Study on Coal
Waste Disposal Options -
Donkin Mine

Concept Study on Coal Waste
Disposal Options from
Proposed Mining Activities at
Donkin Mine - Donkin, Nova
Scotia

Report prepared for:
Xstrata Coal Donkin
Management Limited

Prepared by:

Stantec Consulting Ltd.
845 Prospect Street
Fredericton, NB, E3B 2T7

April 2012
File 121510478.231




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ENVIRONMENTAL IMPACT STATEMENT FOR THE DONKIN EXPORT COKING COAL PROJECT

APPENDIX E
Coal Waste Study




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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE

Table of Contents

1.0 INTRODUCTION .
1.1. MINING DESCRIPTION...
1.2 PROJECT COMPONENTS...

2.0 WASTE DESCRIPTION.
2.1 INTRODUCTION ..
2.2 COAL HANDLING PROCESS PLANT (CHPP)
2.2.1 Desliming and Coarse Coal Circuit.
2.2.2 Mid-Size Circuit.......
2.2.3 Flotation
2.2.4 Waste Handling
2.3 DISTRIBUTION OF MATERIAL SIZES IN PRODUCT STREAM VERSUS WASTE
STREAM
2.4 FEASIBILITY OF COMBINED WASTE STREAM.
2.5 WASTE STORAGE PILE GEOMETRY.
2.6 WASTE STORAGE PILE VOLUMES.
2.7 OTHER POTENTIAL WASTE STREAMS .
2.7.1 Development Waste......
27.2 Dredge Spoils from Marine Works
2.7.3 Acid Rock Drainage Potential...

3,0 POTENTIAL OPTIONS REVIEWED.

3.1 SURFACE STORAGE — DONKIN SI
3.1.1 Waste Storage Options

3.1.1.1 Disposal Option 1....

3.1.1.2 Disposal Option 2

3.1.1.3 Disposal Option 3.

3.1.1.4 Disposal Option 4.

3.1.2 Borrow Site...

3.13 Grubbing Materials Stockpile...
3.1.4 Concept Design Section

3.1.5 Slopes and Stability.

3.1.6 Spontaneous Combustion
3.1.7 Progressive Reclamation and Final Capping.
3.1.8 Haul Truck Movement

3.1.9 Phase Construction
3.2 SURFACE STORAGE - LOCAL REGION
3.3 UNDERGROUND DISPOSAL - ON SITE -
3.4 UNDERGROUND DISPOSAL - LOCAL REGION
3.4.1. Brief Overview of Mine Waste Disposal in Abandoned Underground Workings 3.13
3.4.2 Brief History of Coal Mining for the Sydney Coalfield... seo AS
3.4.3. Summary of Coal Mine Productions for Sydney Coalfield 13.15
3.4.4 Option Evaluation Framework 16
3.4.5 Discussion of Findings...... 3.20

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
‘TABLE OF CONTENTS

3.4.6 Potential Storage Capacity ..
3.4.7 Transportation of Mine Wastes.
3.4.8 Expected Condition of Mine Workings
3.4.9 Potential Constraints Related to Existing Land Development/Usage and/or

Sensitivities .
3.4.10 Summary of Findings and Conclusions
3.5 OCEAN DISPOSAL

4.0 CONCLUSIONS ...

5.0 REFERENCES

List of Figures

Figure 1.1 Location of site
Figure 2.1. A Schematic Block Flow Diagram of the CHPP
Figure 2.2 Grain Size Distribution of WasteStreams...
Figure 2.3 Grain Size Distribution of Product Streams.
Figure 2.4 Grain Size Distribution of Waste Streams..
Figure 3.1. Capping Detail.
Figure 3.2 Stage Storage Curves - Volume vs. Time.
Figure 3.3 General Location of Abandoned Mine Sites Relative to Donkin Mine (Sour.
Google Maps)..

Figure 3.4 General Areas of Historic Mine Workings (Source: NSDNR GIS)
Figure 3.5 Group 1 Historical Coal Mine Sites. a

Figure 3.6 Group 2 Historical Coal Mine Sites.
Figure 3.7 Group 3 Historical Coal Mine Sites

List of Drawings

Drawing 3.1. Disposal Option 1...
Drawing 3.2 Disposal Option 2
Drawing 3.3 Disposal Option 3.
Drawing 3.4. Disposal Option 4

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
‘TABLE OF CONTENTS

List of Tables
Table 2.1 Predicted Waste Quantities
Table 2.2 Plant Feed Material Entering CHPP

Table 2.3. CHPP Product Yield Efficiency...

Table 2.4 Product and Waste Distribution of 1 tonne of Feed Material
Table 2.5 Material Distribution of Product Stream and Waste Stream
Table 2.6 Summary of Grain Size Distribution for Combined Waste Stream
Table 2.7 Summary of Grain Size Distribution for each Waste Stream.

Table 3.2 Sydney Coalfield Coal Production Volumes (1863-1976) ..
Table 3.3 Summary of Mine Sites Considered ...

Table 3.4 General Characterization Summary of Abandoned Mine Sites
Table 3.5 Evaluation of Mine Site Characteristics Against Primary Considerations for

Redevelopment...

List of Appendices

Appendix | - Donkin Site Drawings
4. Option 1
2. Option 2
3. Option 3
4, Option 4 (Preferred)
5. Preliminary construction details

Appendix Il - Cut Sheet data for regional sites

121510478.231 i

April 2012




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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS ~ DONKIN MINE

1.0 Introduction

Xstrata Coal Donkin Management Limited (XCDM) proposes to build upon the existing
Donkin Mine infrastructure to construct and operate an underground coal mine facility capable
of producing coal suitable for the export coal market. It is located on the Donkin Peninsula,
within the Cape Breton Regional Municipality (CBRM), Nova Scotia (Figure 1.1).

Figure 1.1 Location of site

Associated with the mining of the coal resource and the production of the product for export, is
the residual waste stream(s) of rejects from the coal processing streams on site. The potential
manner and location for storage of this waste stream and other site waste components is the
subject of this report.

14 MINING DESCRIPTION

The proposed Export Coking Coal Project is to be located at the existing Donkin Mine site on
the Donkin Peninsula, Cape Breton, Nova Scotia. XCDM proposes a multi-continuous miner
underground operation producing approximately 3.6 million tonnes per annum (Mtpa) of ROM
(run of mine) coal that is subsequently washed to provide 2.75 Mtpa of product coal that is
suitable for the international export coking coal markets. A material handling and processing

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
INTRODUCTION

plant system capable of processing 3.6 Mtpa of raw coal from the Donkin Mine will be
constructed to produce a coking coal ready for presentation to a barge loading facility and
marine transportation operation.

The life of the mine is proposed to be at least 30 years.

4.2 PROJECT COMPONENTS

‘The proposed Project is a potential 3.6 Mtpa ROM underground mining operation. Use of four
continuous miners is currently planned with the ROM coal produced being beneficiated (i
processed) onsite to produce an estimated 2.75 Mtpa of marketable product coal. This leaves
approximately 0.85 million tonnes per annum as reject materials or waste that must be disposed
of as part of the process.

A raw coal stockpile, reciaim, and sizing system will be constructed to prepare a minus 50 mm
raw coal feed to the Coal Handling Preparation Plant (CHPP). The 650 tonnes/hour (vh)
processing plant features a single stage large diameter dense medium cyclone to process coal,
spirals to process the mid-size material, and flotation to process the fine coal. A product
sampling and reclaim system will prepare product coal ready for loading onto a barge or truck
load-out facility.

Product coal is reclaimed to an overland conveyor that feeds directly to a barge loading facility
proximal to the Donkin headland in Morien Bay. Coastal barges of 4,000 tonne capacity are
loaded and then towed by tug to a transshipping location within Mira Bay where the coal is
transshipped to bulk vessels.

The reject CHPP materials are similarly prepared for dry disposal and are loaded out by
conveyor to a site stockpile from where they are available for relocation to permanent storage.

‘The Project includes the following fundamental components:

an underground coal mine;

a coal handling preparation plant (CHPP) with a product sampling and reclaim system to
prepare product coal and a dry disposal reject handling system;

+ ancillary services to support the underground mine and CHPP (administration building,
workshop, coal weighing and sampling facilities, dust suppression systems, conveyors,
stackers, reclaim units and stockpiles, water infrastructure, mobile equipment efc., a new
138 kV power line from Victoria Junction to the Project site); and

* a barge load-out facility proximal to the Donkin headland and barges to transport product
coal to a transshipping location within Mira Bay.

+ Ancillary services to support the barge load-out facility (material handling outhaul conveyor,
radial, luffing telescopic stacker; fuel lines and valving for fueling of vessels; light and power
and potable water supply).

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
INTRODUCTION

‘The location and inter relationship of the various site components are established by others and
for this review of waste disposal options, all infrastructure locations have been considered fixed

(CBCL 2012).

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS ~ DONKIN MINE

2.0 Waste Description

24 INTRODUCTION

In order to facilitate the design of the various storage options under consideration for the waste
coal rock generated from the coal production process, a breakdown of each phase of the coal
handling process; from the raw coal retrieved in the mine to the completion of the handling
process was developed, Two materials types are generated during this process; the product
(yield) to be marketed and the waste (rejects) which are to be handled in a waste storage
capacity. Two additional waste streams must be considered for disposal as well; one for waste
rock generated by mine development for the third tunnel (Tunnel No. 1) in year 4, and dredging
spoils from the development of the barge load-out facility.

The annual and total mine life tonnages and quantities that need to be addressed for the Donkin
project are presented in Table 2.1, and are based on a 30 year mine life.

Table 2.1. Predicted Waste Quantities

Day. th 20
Daily, mh oS — if —

Annual tonnage, t 850,000 200,000 -

‘Annual volume, m? 654,000 ~ 180,000 c

Life of ine 255 rilon 200,000

Ute of mine. 72.6 milion | 70,000 i280

Mining operations will occur below the ocean floor at rock depths of greater than 200 m below
sea level, where existing access has already been established to the mining face. The mine
design and mining operation is based on the use of standard continuous miner (CM) sections.
A section consists of one CM, one roof bolter, and three shuttle cars. Depending on the roof
conditions, the CM advances the entry or crosscut face on average 6 m and then moves to the
next place to be cut. If the roof conditions allow, extended cuts up to 12 m could be taken. The
roof bolter then moves into the recently mined place and installs the roof bolts and other
secondary supports that make up the immediate roof support.

Given the depth of the reserves at Donkin, large pillars will be left during advance under the

deeper cover of a significant portion of the reserve. Retreat mining and partial extraction of the
pillars will be utilized later in the mining sequence,

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
WASTE DESCRIPTION,

The raw coal handling system will receive coal directly from underground, then stockpile on
surface and then convey and size to minus 50 mm and convey the sized materials to the CHPP
at 650 t/h. Raw coal emerging from the underground tunnel via the drift conveyor will be
deposited onto a stockpile. The “as mined” coal was assumed to have a top size of 250 mm.
The stockpile is necessary to disconnect the mine operations cycle from the plant operations
cycle to allow for the higher mining rate and fluctuations in underground production.

2.2 COAL HANDLING PROCESS PLANT (CHPP)

Discharge from the reclaim conveyor will be directed to a two stage crushing system comprising
a sizing station to produce a minus 50 mm plant feed material. The crushed raw coal will
discharge onto the plant feed conveyor which in turn will discharge directly into the desliming
screen feed box on the top of the CHPP building.

The coal handling process can be generalized as follows:

1. Raw coal is extracted from the mine at a maximum aggregate diameter of 250 mm and
stockpiled at surface.

2. The raw coal is taken from the stockpile and fed into a 2 stage crusher to produce a 50 mm
minus material.

3. The 50 mm minus material is fed into the CHPP, consisting of a three stage process.

4. Each of the processes handles a specific material size and generates a product stream and
a waste stream, each with a unique and varying product yield and recovery efficiency.

5. The Dense Medium Cyclone handles material sizes between 50 mm and 1.4 mm in
diameter (large size). Spirals will handle 1.4 mm to 0.25 mm (mid-size) and Flotation is
proposed for the 0.25 mm and below materials (fine size). Since each process has a range
of efficiency (yield), the percentage of material sizes entering the CHPP will not necessarily
‘equal the percentage of material sizes being generated in the product and waste streams.

6. Reject materials from each process will be dried and combined before being transported to
the waste stockpile.

A simplified process diagram is presented in Figure 2.1, with further description of the general
process presented in the following text.

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
WASTE DESCRIPTION

Figure 2.1. A Schematic Block Flow Diagram of the CHPP

= DONKIN CHPP
secouire J SIMPLIFIED BLOCK DIAGRAM

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2.2.1 Desliming and Coarse Coal Circuit

Plant feed coal will be slurried in the desliming screen feed box and fed onto a multislope
desliming screen. The -1.4 mm wet weight (ww) material and water will be collected in an
underpan and piped to a desliming cyclone feed sump. The -50 to +1.4 mm (ww) material will
discharge from the desliming screen and be flushed into a dense medium cyclone (DMC) feed
sump.

Product coal will be directed to coarse coal centrifuges for dewatering prior to being discharged
onto a product conveyor.

Reject coal will underflow from the dense medium cyclone into a tile lined screen feed box
which will direct the reject material onto a reject conveyor.

2.2.2 Mid-Size Circuit
The desliming screen undersize (1.4 mm (ww) material will be pumped to a cluster of destiming
cyclones. The cyclones will classify the feed at approximately 0.250 mm, with the underflow

(+0.250 mm) gravitating to spirals and overflow (-0.250 mm) reporting to the flotation feed
sump.

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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
the product conveyor.

Spiral rejects will gravitate to a high frequency dewatering screen. Dewatered rejects will
discharge onto the reject conveyor, and screen underflow will report to the thickener.

2.2.3 Flotation

Desliming cyclone overflow and spiral product thickening cyclone overflow will be combined in
the flotation feed sump and pumped to a single Jameson Cell

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
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.

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




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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

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~ 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




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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.

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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




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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
WASTE DESCRIPTION

Figure 2.3 Grain Size Distribution of Product Streams

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‘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




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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE

WASTE DESCRIPTION,

Figure 2.4 Grain Size Distribution of Waste Streams

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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





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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.

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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).

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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.

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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

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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

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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.

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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

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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

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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.

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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.

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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

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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.

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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.

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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

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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

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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

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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.

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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.

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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

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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

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Figure 3.3 General Location of Abandoned Mine Sites Relative to Donkin

ine (Source: Google Maps)

DONKIN
MINE

Broughton/4 Star

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Figure 3.4 General Areas of Historic Mine Workings (Source: NSDNR GIS)

LEGEND
coal Workings

&

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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.

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Table 2.3 General Characterization Summary of Abandoned Mine Sites

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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.

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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

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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

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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.

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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.

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* 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).

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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 :





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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

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\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

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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.

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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

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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

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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.

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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

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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.
Retrieved December 2011, from ArcIMS Viewer:
fitp://gis4.natr. gov.ns.ca/website/nsgeomap/viewer.htm

Nova Scotia Environment. (2009). Guide for Surface Coal Mine Reclamation Plans.

‘Sedgman (May 2010). Donkin Project, CHPP Pre-Feasibility Study Report.

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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE
REFERENCES

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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CONCEPT STUDY ON COAL WASTE DISPOSAL OPTIONS - DONKIN MINE

APPENDIX |

Donkin Peninsula Surface Deposition Options








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