Management Measures Chapter 9 | Biological Impacts and

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Chapter 9 | Biological Impacts and Management Measures

Chapter 9 | Physical Impacts and Management Measures

Mako Gold Project

Environmental and Social Impact Assessment

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Chapter 9 | Physical Impact Assessment

9 PHYSICAL IMPACT ASSESSMENT ............................................................................. 9-1

9.1 Project Footprint ...................................................................................................................................................... 9-3

9.1.1 Issues and Findings ................................................................................................................................... 9-3

9.1.2 Avoidance, Mitigation and Management Measures ...................................................................... 9-5

9.1.3 Residual Impact Assessment ................................................................................................................. 9-7

9.2 Mine Pit and Waste Rock Disposal...................................................................................................................... 9-9

9.2.1 Issues and Findings ................................................................................................................................... 9-9

9.2.2 Avoidance, Mitigation and Management Measures .................................................................... 9-11

9.2.3 Residual Impact Assessment ............................................................................................................... 9-14

9.3 Tailings Disposal ..................................................................................................................................................... 9-15

9.3.1 Issues and Findings ................................................................................................................................. 9-15



9.4 Hydrology ................................................................................................................................................................. 9-19




9.5 Hydrogeology ......................................................................................................................................................... 9-30




9.6 Surface and Ground Water Quality .................................................................................................................. 9-33




9.7 Soils ........................................................................................................................................................................ 9-46




9.8 Air Quality ................................................................................................................................................................. 9-51

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9.9 Noise ........................................................................................................................................................................ 9-62




9.10 Vibration and Airblast ........................................................................................................................................... 9-71




9.11 Flyrock ........................................................................................................................................................................ 9-76




9.12 General Waste and Hazardous Materials ....................................................................................................... 9-78




9.13 Accidental Events and Natural Hazards ......................................................................................................... 9-86




9.14 Climate and Greenhouse Gases ........................................................................................................................ 9-93




9.15 Visual Amenity ..................................................................................................................................................... 9-101

9.15.1 Issues and Findings .............................................................................................................................. 9-101

9.15.2 Avoidance, Mitigation and Management Measures ................................................................. 9-109

9.15.3 Residual Impact Assessment ............................................................................................................ 9-110

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9 PHYSICAL IMPACTS AND MANAGEMENT MEASURES

The development of the Mako Gold Project will lead to physical environmental impacts during construction,

operation and Project decommissioning, with some residual physical impacts continuing post-closure.

Management, mitigation and monitoring measures will be implemented to avoid, minimise or mitigate

impacts to the extent practicable. Diligent application of best practices for managing potential impacts is

expected to significantly decrease the potential for residual impacts. Detailed management plans for

potential impacts are provided in:

Technical appendices to this ESIA (Volume A);

Management plans including the Environmental and Social Management and Monitoring Plan

(Volume C) and the Rehabilitation and Conceptual Mine Closure Plan (Volume E); and

Select chapters of the ESIA.

The following chapter summarises potential physical impacts from Project pre-construction / construction,

operation and decommissioning / closure and summarises management measures that are intended to

minimise residual impacts. Where significant differences in the potential impacts are expected to occur

between the various Project phases, these have been highlighted. Associated potential impacts to

environmental and social receptors are provided in Chapters 10 and 11, respectively.

Where feasible, the Project has been designed to reduce physical environmental impacts and their associated

biological and social impacts. The primary components of the Project that have the greatest potential to

physically impact the environment include the Petowal Mine Pit, Waste Rock Dump (WRD), Tailings

Management Facility (TMF), Process Plant and ROM Pad, Power Station and the Mine Services Area (refer to

Chapter 4). These facilities are located and designed to minimise environmental and social risk while

providing for an economically viable mining operation. Lesser physical impacts may be associated with the

Water Storage Dam (WSD), accommodation camps, quarries and access roads. Handover of some facilities

(pending the results of stakeholder consultation) to government or communities may derive beneficial

outcomes from physically impacted areas (e.g. road infrastructure and accommodation camps).

The following sections highlight potential physical impacts during construction, operation and post-closure

and provide management strategies established to avoid, minimise or mitigate potential impacts.

Impacts Categories

Project associated impacts are herein defined according to the following categories (refer to Figure 9-1):

Permanent impact: Project development permanently alters the physical landscape / feature to the

extent that it cannot be rehabilitated to provide self-sustaining native habitat;

Permanent impact – asset transfer: Project development permanently alters the physical landscape /

feature but the Project component will provide lasting benefit to the government or local communities

via asset transfer;

Temporary impact – rehabilitated to a natural ecosystem: Project development alters the physical

landscape / feature, however the impacted area will be rehabilitated and revegetated to provide self-

sustaining natural habitat; and

Temporary impact – access restriction: Project development does not physically impact the

landscape / feature, however community access to the area will be restricted or prohibited during

Project construction, operation and decommissioning (social impact) for safety considerations.

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Figure 9-1 Project Footprint and impact category

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9.1 Project Footprint

9.1.1 Issues and Findings

This section considers potential impacts (and management / mitigation) to the physical landscape associated

with Project development. Associated impacts (e.g. to hydrology, water quality, and air quality etc. for each

Project component) are discussed in Sections 9.2 to 9.15.

The Project Footprint will comprise approximately 248.3 ha of land surface that will be subjected to

permanent or temporary physical impacts (refer to Figure 9-1). Approximately 74.3 ha will be permanently

impacted via development of the Project Footprint. Ownership of the facilities constructed on approximately

38.9 ha of this area will be transferred to government or local communities, providing a long-term benefit.

Approximately 174.0 ha of surface area will be temporarily impacted but will be rehabilitated and

revegetated to provide sustainable native ecosystems (refer to the Rehabilitation and Conceptual Mine Closure Plan, Volume E).

The PDA will be prescribed to prohibit or restrict access to buffer areas around Project facilities (refer to Figure

9-2) during the life of the mine to minimise potential health and safety risks. Enforcement of the PDAs will

increase the area of temporary impact via access restriction for residents of the region that currently utilise

this land. Temporary access restriction will not enhance the area of physical impacts, but may increase the

area of temporary socio-economic impacts and are therefore not evaluated in this chapter.

Development of the Project will impact 247.1 ha (surface area) of landform morphology and soil / subsoil

during construction and operation. Details for each Project facility are provided in the following section.

The Project has been designed to minimise the physical impacts to the natural landscape by minimising the

Project Footprint to the extent practicable. The WRD, TMF, Petowal Pit, Mine Services Area, ROM Pad and

Process Plant, and a significant portion of the road infrastructure will be almost exclusively located within one

relatively small catchment (Badalla Valley).

Pre-Construction / Construction

Site Preparation - The majority of physical impacts to landforms in the PDA will occur during Project

construction. The first phase of facilities’ construction will include vegetation clearing and grubbing;

preparatory earthworks; and topsoil removal (for specific facilities). Table 9-1 summarises the general impacts

of site preparation, which are discussed in detail in applicable Sections of this chapter.

Table 9-1 Summary of potential physical impacts related to site preparation during Construction

Impacts Assessment Reference Section

Erosion and

Sedimentation

Clearing and grubbing of vegetation, major earthworks, soil stockpiling, soil

compaction will increase the likelihood of soil erosion from water and wind with

subsequent sediment transport

Section 9.6

Section 9.8

Soil Compaction Heavy earthmoving equipment and pad / road preparation will compact surface

or subsoils (pending topsoil removal)

Section 9.7

Water Quality Diesel powered vehicles / equipment provide potential sources of

hydrocarbons to surface and groundwater and accommodation camps a

potential source of nutrients and pathogens

Section 9.6

Hydrology Surface water from seasonal drainages will be diverted around disturbance

areas, in some cases to sumps and / or permanent drainage channels

Section 9.5

Air Quality Particulate matter (dust) will be generated from clearing and grubbing, topsoil

stripping and stockpiling, vehicle transit on unsealed road networks, etc.

Exhaust emissions (e.g. CO, NOx, SO2, VOCs) will be generated from diesel

powered vehicles / equipment and Power Station

Section 9.8

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Impacts Assessment Reference Section

Noise Vehicles / equipment will be a source of noise emissions during site

preparation. Blasting at quarries / road construction areas will be a short term

source of high intensity noise

Section 9.9

Vibration Blasting at the pit / quarries / road construction areas will provide airblast and

ground vibration and vehicle / equipment utilisation a source of vibration during

site preparation.

Section 9.10

Primary physical impacts to the Project Footprint during construction comprise the permanent or temporary

conversion of landforms from natural landscapes to Project components. Direct impacts, per Project

component include:

Petowal Mine Pit: the majority of pit development will occur during operation. However, site

preparation activities initiated early in the Construction Phase will include topsoil stripping and

transport to topsoil stockpiles (for subsequent revegetation efforts) and subsoil stripping (if of

adequate engineering grade) to provide material for various Project components (e.g. TMF and WSD

embankment material, road fill, etc.). The 35.4 ha Mine Pit surface will be stripped of topsoil to a depth

of approximately 0.5m (180,200 m3 topsoil). It is anticipated that subsoil will also be excavated and

transported for construction fill.

Waste Rock Dump: The majority of WRD development will occur during operation. However, site

preparation activities and topsoil reclamation will occur during construction. Following vegetation

clearing and grubbing, topsoil will be stripped from the 77.3 ha WRD footprint to a depth of 0.5m

(404,600 m3 topsoil), permanently impacting the landform and temporarily impacting the site’s ability

to support native vegetation.

Tailings Management Facility: The TMF dam wall will be constructed to height of 15 m during the

Construction Phase and will be incrementally increased to height of 26 m during mine operation.

Construction of the dam will impact 2.45 ha for the final TMF embankment and will require a

significant volume of suitable engineering material (clay rich material).

This material may be sourced from the Mine Pit overburden or WRD footprint, however it may require

excavation from local borrow areas which may expand the area of physical impact for TMF and WSD

construction (refer to below).

ROM Pad, Process Plant, and Power Station: Construction of these facilities will require clearing and

grubbing; stripping of topsoil for post-closure rehabilitation (if applicable); and import of foundation

material (e.g. sand and gravel), temporarily converting 15.9 ha (9.3 for the Process Plant and Power

Station and 6.6 ha for the ROM Pad) of vegetated area to a built environment.

Water Storage Dam (WSD): Construction of the WSD will permanently impact 14.9 ha of vegetated

area in the Wayako catchment, via construction of the dam, the permanent water holding facility, the

pump station adjacent to the Gambia River, and pipelines between the facilities.

WSD dam construction will require import of suitable engineering material (clay rich material, sand,

gravel and rip-rap) that will be sourced from local borrows (refer to below).

Main Access Road: The main access road will be constructed from highway RN7 to the Mine Services

Area in Badalla Valley. Secondary roads will be constructed that branch from this road to access the

WSD from the north, the Mine Pit, the WRD, and the TMF. Construction of this main access road

network will require clearing and grubbing, import of sub-base and base material and compaction of

the topsoil. Approximately 30.9 ha of vegetated area will be permanently converted to the road

facility.

Additional Construction Phase Road Infrastructure: The existing road running parallel to the

Gambia River between Mako and Linguekoto will be upgraded to support vehicle transport from

workforce accommodation in Mako and the Exploration camp and construction sites during early

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Construction Phase works (prior to completion of the Main Access Road). Approximately 5.7 km of

existing road will be upgraded and widened. The area of impact to native vegetation depends on the

extent of proposed road-widening for the road facilities.

Mine Services and ancillary facilities: Construction of the Mine Services Area, Explosives Magazine,

and vehicle laydown facilities will temporary convert surface land to Project facilities. Construction

activities, including clearing and grubbing, levelling, compaction of surface soils, development of

drainage, etc. will temporarily impact approximately 2.5 ha of vegetated area, predominantly in the

Badalla catchment.

Workforce accommodation: Construction of the primary workforce accommodation areas will require

conversion of approximately 3.6 ha of vegetated area to a permanent facility.

Quarries: Earth-fill borrow material will be required for concrete batching (for facilities construction),

WSD embankment, TMF embankment, and road construction / upgrade activities. Much of the sand is

expected to be hauled to site from a quarry toward Dakar. Additional borrowing activities will likely

occur on-site, potentially impacting some land at quarry sites for material that cannot be sourced from

the Mine Pit overburden. However, existing quarries (refer to Figure 4-1) within the Project Concession

Area have been previously disturbed (and not rehabilitated), and are expected to be utilised for Project

borrow requirements, minimising the potential for any additional significant impacts. Impact area

determination for additional quarry areas requires further investigation.

Operation

Potential direct impacts include:

Petowal Mine Pit: Development of the Mine Pit will permanently impact 35.0 ha of surface land. A

portion of the ridge encompassing the boundary of the Badalla and Kelendourou catchments will

progressively be converted to a pit throughout operation. Approximately 73.6 Mt of material will be

excavated and transported to the ROM Pad / Process Plant, ore stockpile, or WRD during development

of the pit. The Petowal Mine Pit will be excavated to a final depth of approximately 100 metres above

sea level (masl), with the pit rim varying between approximately 260 - 355 masl.

Waste Rock Dump: Approximately 62.4 Mt of waste material will be moved from the Mine Pit to the

WRD, permanently altering the landform (77.3 ha footprint). The morphology of a significant portion of

the Badalla Valley will progressively be transformed to a higher elevation landform throughout Project

operation.

Ore stockpile: Excavated ore in excess of that which can be immediately processed will be stored at

the ROM Pad stockpile or Ore Stockpile (6.3 ha) during operation. Construction of the stockpiling areas

will require clearing and grubbing, stripping of topsoil, and construction of cut-off drains, temporarily

altering the landform.

Tailings Management Facility: Approximately 54.9 ha in the lower reach of the Badalla Creek Valley

will be temporarily impacted, with conversion of the vegetated area to a subaerial tailings holding

facility during operation.

Decommissioning / Closure

The area of physical impact will be reduced during decommissioning via rehabilitation of temporarily

impacted land surfaces to meet closure criteria (refer to below). No additional physical impacts to the Project

Footprint are anticipated during this phase of the Project.

9.1.2 Avoidance, Mitigation and Management Measures

Avoidance

The Project has been designed to avoid the physical impacts to the natural landscape by reducing the Project

Footprint to the extent practicable. Most notably, the WRD, TMF, Petowal Pit, Mine Services Area, ROM Pad and

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Process Plant and a significant portion of the road infrastructure will be almost exclusively located within one

relatively small catchment (Badalla Valley).

Minimisation

Project facilities have been designed for geotechnical stability, with size and substrate considerations

including probable peak storm events and potential natural disasters, minimising the potential area affected

by and consequences of significant landslips or dam failure (refer to Section 9.11) and associated impacts to

water quality (refer to Section 9.6).

During construction, the majority of direct impacts will be associated with land clearing / topsoil removal

activities and conversion of native landforms to Project components.

Management and mitigation measures to minimise potential direct impacts to land areas during construction

include:

Minimising the size of the Project Footprint, where feasible; and

Surveying, delineating and demarcating the maximum extent (area) of earthworks for each Project

component and enforcing prohibition of vehicular / equipment access outside of the designated

Project Footprint.

Long-term physical impacts will be minimised through activities outlined in the Rehabilitation and Conceptual Mine Closure Plan (Volume E) that will progressively reduce the size of the Project footprint via

specific rehabilitation and revegetation activities (Refer to the section below).

Rehabilitation / Decommissioning / Closure

Landforms will be progressively rehabilitated throughout construction or immediately following

construction. This will apply to areas that are not required during operation, including buffer areas required

for construction equipment (e.g. road embankments, access for construction equipment for facilities

including the Mine Services Area, workforce accommodation areas, Process Plant and ROM Pad, etc.).

During Project the Operation Phase, the Mine Pit, WRD, and TMF will be progressively expanded, with

development converting additional area of natural landform to Project facilities throughout the life of the

mine. Some features of these components can be progressively rehabilitated and revegetated throughout

operation (refer to the Rehabilitation and Conceptual Mine Closure Plan, Volume E).

Progressive rehabilitation activities are expected to include:

The WRD, constructed in lifts from the bottom up, may be progressively rehabilitated (graded to

contour, geotextile and topsoil applied, and revegetated) following completion of each lift; and

Buffer areas adjacent Project components that were required for equipment access during

construction may be progressively rehabilitated throughout operation to reduce the size of the Project

Footprint.

Development of Project components during construction and operation will disturb landforms according to

impact definitions provided above (Permanent, Permanent – Asset Transfer, Temporary – Rehabilitated to a

Natural Ecosystem and Temporary – Access Restricted) (refer to Figure 9-1). Project decommissioning /

closure activities will progressively reduce the size of the Project Footprint for temporarily disturbed areas,

minimising long-term physical impacts via specific rehabilitation and revegetation activities. Detailed

strategies are provided in Volume E, Rehabilitation and Conceptual Mine Closure Plan. Table 9-2

summarises the anticipated actions that will be undertaken during decommissioning and closure to reduce

the post-closure Project Footprint. Additional measures to manage and mitigate for additional physical

impacts (e.g. air quality, water quality, noise, vibration) are detailed in subsequent sections.

Table 9-2 Summary of Decommissioning activities per Project component

Project

Component

Impact Category Decommissioning / Closure Strategies

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Project

Component

Impact Category Decommissioning / Closure Strategies

Mine Pit Permanent Rehabilitation and revegetation of Pit margins and temporary equipment

access roads.

WRD Temporary –

Rehabilitated to

Natural Ecosystem

The WRD will be graded to contours that align with adjacent topography.

Erosion matting / geotextile and topsoil will be applied and the WRD surface

revegetated with native species of local provenance to create a Tree

savannah or Shrub savannah and grassland vegetative community.

Ore Stockpile Temporary –

Rehabilitated to

Natural Ecosystem

The footprint of the Ore Stockpile will be rehabilitated and revegetated with

native species of local provenance to create Tree savannah or Shrub

savannah and grassland vegetative community.

TMF Temporary –

Rehabilitated to

Natural Ecosystem

The majority of the TMF (other than rock-lined drainage channels) will be

rehabilitated and revegetated to create a Shrub savannah vegetative

community.

A base-layer (subsoil) will be placed on top of tailings and topsoil (to 150mm

depth) applied above the base-layer.

Rock-lined drainage channels will remain in place, with grasses /

herbaceous plant species expected to eventually establish some of the

channel area. Native trees will be planted along drainage channels /

Badalla Creek.

Process Plant

and ROM Pad Temporary –

Rehabilitated to

Natural Ecosystem

The Process Plant and ROM Pad will be dismantled. The surface soil will

be ripped to approximately 1 m and the area revegetated to re-create the

grassland vegetative community.

Power Station Temporary –

Rehabilitated to

Natural Ecosystem

The Power Station will be dismantled. The surface soil will be ripped to

approximately 1 m and the area revegetated to re-create the Tree savannah

or grassland vegetative community.

WSD Temporary –

Rehabilitated to

Natural Ecosystem

The embankment will be breached and removed, the morphology of the

ephemeral stream rehabilitated, and the area revegetated to re-create a

Tree savannah or Wooded savannah vegetative community.

Main Access

Road Permanent – Asset

Transfer It is anticipated that the Main Access Road, remaining Road Infrastructure,

and workforce accommodation facilities will be transferred to the local

government or communities (pending stakeholder consultation). Road

infrastructure in the PDA will be rehabilitated

Road

Infrastructure Permanent – Asset

Transfer

Workforce

Accommodation Permanent – Asset

Transfer

PDA (no

physical

impacts)

Temporary – Access

Restricted

The PDA will not be enforced following Project closure. Former agricultural

areas, livestock grazing areas, artisanal mining areas, etc. will be returned

to previous landholders / land users without Project restriction.

9.1.3 Residual Impact Assessment

The majority of the impacts associated with the disturbance of the Project Footprint, will occur during the

Pre-Construction / Construction Phase. In total, development of the Project will impact 248.3 ha (surface area)

of landform morphology and soil / subsoil during construction and operation.

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No additional land disturbance is expected outside the Project Footprint area during the Operation Phase.

Progressive rehabilitation and revegetation will restore some temporarily disturbed areas back to a natural

ecosystem during this phase.

While the majority of the Project Footprint will be rehabilitated and revegetated at closure, portions of the

Project Footprint will not be converted back to a natural ecosystem, including facilities / assets that will be

formally transferred to government or community ownership. Table 9-3 identifies the area of permanent

(residual) impact.

Table 9-3 Residual physical impact areas Post-Closure

Project Component Residual Physical Impact Area Post-Closure

Mine Pit The 35.40 ha (surface area) Mine Pit void will be a permanent feature in the landscape

Main Access Road The 25.6 ha Main Access Road will be transferred to government ownership, providing lasting

benefit to the region

Road Infrastructure The majority of road infrastructure, including existing roads that were widened during

construction and those constructed for Project operation, will remain following Project closure,

providing lasting benefit to the region, albeit permanent physical impact. It is anticipated that

6.5 ha of the 32.04 ha road infrastructure network will be rehabilitated to provide a natural

ecosystem.

Workforce

Accommodation It is anticipated that the ownership of the 3.58 ha workforce accommodation camp and

3.24 ha exploration camp will transferred to government or local villages

The key expected residual impacts related to the Project Footprint under normal operating conditions, and

their overall significance for each Project phase, are summarised in Table 9-4. Monitoring will be required over

the mine life to confirm the residual impact predictions, and allow management measures to be adapted

accordingly.

Table 9-4 Summary of key expected pre-mitigation impacts, mitigation measures and residual impacts for the

Project Footprint for each Project phase

Receptor / Value

Expected Pre-Mitigation Impact

Significance

Key Management & Mitigation Measures

Key Expected Residual Impacts and Overall Impact Significance


Project Footprint

MODERATE

Minimising the size of the Project Footprint, where feasible

Surveying, delineating and demarcating the maximum extent (area) of earthworks for each Project component

Other management and monitoring measures for water quality, hydrology, dust, noise etc.

MODERATE

Land clearance, topsoil removal and earthworks within Project Footprint.

Total area of Project Footprint is 248.3 ha (surface area)

Operation

Project Footprint

MODERATE

As per Pre-Construction / Construction Phase

Restoration activities conducted in accordance with Rehabilitation and Conceptual Mine Closure Plan

Routine checks for compliance

MINOR

Some areas will continue to be cleared during operation within the PDA (e.g. within the WRD area)

Progressive rehabilitation and revegetation will restore some temporarily disturbed areas


Project MODERATE Restoration activities conducted in MINOR

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Receptor / Value


Significance




Footprint accordance with Rehabilitation and Conceptual Mine Closure Plan


Portions of the Project Footprint will not be converted back to a natural ecosystem (e.g. pit)

9.2 Mine Pit and Waste Rock Disposal



The development of the Mine Pit and WRD will occur during the Operation Phase, therefore the majority of

potential impacts are associated with operation and decommissioning / post-closure. However, overburden

from the pit may be used for TMF and WSD embankment construction, if the material is found to have

suitable engineering quality. The pit and WRD will also be stripped of topsoil during construction to provide

material for Project rehabilitation during Project decommissioning (and progressively throughout operation).

Potential impacts from land clearing activities and topsoil stripping / transport to stockpiles may include:

Erosion and sedimentation (refer to Section 9.6);

Hydrocarbon spillage (refer to Section 9.6);

Soil compaction (refer to Section 9.7);

Particulate matter (dust) and exhaust emissions (refer to Section 9.8);

Noise (refer to Section 9.9);

Vibration (refer to Section 9.10); and

Hydrology (refer to Section 9.4): Surface water from seasonal streams will be diverted around the Mine

Pit and WRD footprints during site preparations. Impacts are not expected to be significant as surface

water will remain within the Badalla catchment, discharging to Badalla Creek (during construction)

prior to its confluence with the Gambia River.

Operation / Post-Closure

Development of the Mine Pit and WRD may lead to geotechnical and / or geochemical instability, potentially

affecting the landforms and receiving waters.

Geochemistry

Exposure of sulfidic materials to atmospheric oxygen can result in the generation and release of salinity,

dissolved metals and/or acid. Understanding the nature and distribution of reactive minerals within mine

materials is important for identifying potential water quality issues during operation and post closure.

Assessment and classification of mine materials on the basis of geochemical stability allows specific

management strategies to be developed for materials with different geochemical profiles in order to ensure

safe handling and storage in the long term.

MEC engaged Earth Systems and SRK to conduct a geochemical assessment of geological materials from the

Mako Gold Project. Geochemical classification was performed for samples collected from all geological

materials to be handled or disturbed by the mining operation (e.g. Mine Pit wallrock material, Waste Rock

Material, and Ore / Tailings material). Comprehensive results of the geochemical assessment undertaken and

the derivation of the geochemical classification scheme are provided in the Geochemical Assessment and

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Management Strategies for the Mako Project, Senegal (Earth Systems, 2015). In summary, the geochemical risk

associated with waste rock, ore and pit wallrock was found to be low to very low (refer below).

Additional potential impacts to surface or groundwater quality associated with Mine Pit and WRD

development are discussed in Section 9.6 (Surface and Groundwater Quality).

WRD

Progressive disposal of waste rock on the WRD throughout operation will provide a source of material that

may be susceptible to geotechnical and / or geochemical instability. The potential issues include:

Erosion and sediment transport during high intensity rain events (refer to Section 9.6);

Landslips, providing a potential source of sediments to receiving waters (refer to Section 9.13); and

Saline and / or Metalliferous drainage in surface water runoff or seepage to groundwater.

Geochemical testwork of the waste rock samples determined that waste rock leachate pH is expected to be

near-neutral to slightly alkaline, with low levels of sulfate salinity and very low dissolved metal concentrations.

Other potential water quality issues associated with the waste rock material (e.g. nutrients) are discussed in

Section 9.6.

The siting of the WRD within the Badalla Valley, upstream of the TMF, will allow for the capture and retention

of leachate and sediments from the WRD during operation, with the water to be recycled on-site through the

Process Plant.

The stability of the proposed WRD has been assessed under static and seismic loading conditions using limit

equilibrium methods. ‘SLOPE/W’ has been used for the analysis using the Morgenstern-Price method of limit

equilibrium method of analysis by Knight Piesold (Knight Piesold, 2015g). The modelling results indicate that

the WRD will possess adequate stability for the modelled scenarios and conditions. However, the results

identify that WRD stability is sensitive to the level of the phreatic surface. Mitigation measures are therefore

required, as described in Section 9.2.2.

Mine Pit Wallrock

Geochemistry of the Mine Pit wallrock is expected to be similar to that of the waste rock, with a small

proportion of the Pit wallrock expected to be similar to the ore samples. Leachate from the Mine Pit wallrock

is expected to be near-neutral to slightly alkaline, with low levels of sulfate salinity and very low dissolved

metal concentrations. Other potential water quality issues associated with the Pit wallrock material (e.g.

nutrients) are discussed in Section 9.6.

Water from dewatering from the Mine Pit during operation will be pumped to the Process Plant to

supplement water Project water supply.

Ore Stockpile

As for the WRD, progressive stockpiling of ore throughout operation will provide a source of material that

may be susceptible to geotechnical and / or geochemical instability. The potential impacts include:

Erosion and sediment transport during high intensity rain events (refer to Section 9.6);

Landslips, providing a potential source of contaminants to receiving waters (refer to Section 9.13); and

Saline and / or Metalliferous drainage in surface water runoff or seepage to groundwater.

Testwork indicates that the AMD risk associated with the ore material is generally low. Approximately 87% of

the ore / tailings samples analysed were classified as non-acid forming (NAF).

All of the basalt lithology unit ore / tailings samples were classified as NAF; and

Two out of 16 samples were classified as potentially acid forming (PAF).

The PAF sample from the felsic lithology unit was classified as having a moderate-high potential for acid

generation and represents approximately 13% of the Felsic ore / tailings samples analysed. The other sample

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was a composite sample of weathered ore material and was classified as having a low potential for acid

generation. The sulfide oxidation rate for the stockpiled ore material is expected to be similar to the waste

rock material, given the expected similar particle size distribution of the materials in the WRD and ore

stockpile. This sulfide oxidation rate is expected to translate to very low sulfate salinity generation rates. Ore

stockpile leachate pH is expected to be near-neutral to slightly alkaline, with low levels of sulfate salinity and

very low dissolved metal concentrations.

The siting of the ore stockpile within the Badalla Valley, upstream of the TMF, will allow for the capture and

retention of leachate and sediments from the ore stockpile during operation, with the water to be recycled

on-site through the Process Plant.


Avoidance

MEC will implement specific measures to reduce potential impacts associated with land clearance / site

preparation and topsoil removal activities (e.g. erosion and sedimentation, hydrocarbons spillage, soil

compaction, air quality impacts and altered hydrology) during construction.

Management and mitigation measures to avoid potential impacts are provided in Section 9.4 (Hydrology),

Section 9.6 (Surface and Groundwater Quality), Section 9.7 (Soils) and Section 9.8 (Air Quality).

Geochemistry

On-going monitoring of waste rock and ore geochemistry will allow for placement of identified reactive

materials within sufficient neutralising or containment materials to avoid development of AMD/NMD issues.

Water Quality

Strategic water quality management issues generated by the ore stockpile and WRD will be avoided by the

‘zero operational discharge’ mine design. The Mine Pit dewatering stream will also be diverted for use as

mine process water. Some minor volumes of mine water may not be collected as seepage from the TMF, this

will be monitored and avoided or minimised through treatment if required.

Ore Stockpile

All ore from the Ore Stockpile (and ROM ore stockpile) will be processed prior to Project decommissioning.

Minimisation

Geotechnical stability of Mine Pit

The engineered pit design incorporates design elements to minimise the risk of block, wedge or planar

sliding within the Mine Pit. Geotechnical analyses by Cube (2014) and SRK (2014c), including: assessment of

geotechnical characteristics of the Petowal deposit (rock mass, structures, and hydrogeology); and stability

assessment (limit equilibrium analysis and kinematic analysis) were used to generate slope design

recommendations.

Inter-ramp angles in fresh rock units will be 56º (20 m bench height, 8 m berm width, 75º bench face

angle);

Overall slope angles will vary between 53º and 55º on the hanging wall depending on the number and

width of ramp off-sets on each slope;

Overall slope angles will vary between 44º and 48º on the footwall slopes depending on the number

and width of ramp off-sets on each slope; and

Overall slope angles include flatter oxide zone slopes for weathered material (~10 m bench height, 10

m berm width, 75º bench face angle).

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FINAL 9-12

Water Quality in Mine Pit

Rainwater and groundwater will be diverted to a pit sump. Pit sump water will be regularly monitored for

water quality.

Mine Pit sump water will be pumped to the Process Plant to supplement process water requirements. Pit

water will not be discharged to the environment during operation.

Waste Rock Disposal

The geochemical risk associate with the waste rock material is very low. The primary mitigation strategy for

potential impacts from the WRD is locating it in the Badalla Valley, upstream of the TMF. The TMF will be

utilised during operation as a sediment retention dam to capture drainage from the WRD and allow for the

retention and re-use of this water on-site during operation. Surface water will not be discharged to receiving

waters during operation.

Additional WRD design and / or management strategies that are likely to be effective in further reducing the

potential low level water quality impacts related to the geotechnical / geochemical stability of the waste rock

include:

Routine monitoring of surface water and groundwater quality downstream of the WRD during the

Operation Phase to identify any potential water quality impacts associated with the WRD; and

If the geochemical risk of the waste rock material is found to increase during operation, a Geochemistry

Management Plan should be developed for the WRD.

Surface water drainage from the Badalla catchment will be diverted around the WRD to minimise erosion of

the facility, where possible.

To reduce WRD instability risks, drainage measures will be provided to direct surface water away from the

WRD, to reduce water infiltration and to reduce the level of the phreatic surface that develops. The WRD be

constructed from the bottom up so that the toe support is provided to the sections of WRD located on

steeper and higher ground. An additional recommendation is that, during the initial mining phase a further

stability and deformation investigation analysis is undertaken to refine the WRD stability analysis (Knight

Piesold, 2015j).

Ore Stockpile

During operation, excavated ore in excess of that which will be processed in the short-term will be

temporarily stockpiled (refer to Figure 9-1).

The ore stockpile will be located adjacent the WRD, within the Badalla Valley. As per the WRD, surface

water draining the Badalla catchment will be diverted around the stockpile, where possible. Drainage

from the ore stockpile will report to the TMF for re-use of this water on-site during operation. Surface

water will not be discharged to receiving waters during operation; and

Erosion and sediment control facilities will be constructed to minimise losses of stockpiled ore and

potential transport to receiving waters. Surface water will be diverted to the TMF for storage, with a

portion of the water pumped to the Process Plant for use as process water.

The geochemistry of the ore and the chemistry of drainage from the stockpile will be monitored throughout

operation to confirm whether the potential risk associated with the material remains low.

Mine Pit

The closure water balance for the pit indicates the formation of a pit lake that overflows seasonally for two

months approximately 20 years after cessation of dewatering in 2045. In the first year the pit lake will be

elevated in some water quality parameters, but this will quickly be diluted with additional rainfall and

groundwater inflow. By the point of discharge occurring pH is predicted to be neutral, salinity (TDS) will likely

be approaching 500 mg/L, most metals (including Cu, Zn, Mn Sb) will be under ambient guideline levels, while

As and Pb may be slightly elevated. Management and monitoring measures to include:

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FINAL 9-13

If required, establish a passive anaerobic wetland system to lower sulfate salinity and dissolved metal

concentrations in the pit lake via sulfate reducing bacteria.

Design the pit lake to include management strategies that will minimise hydrogen sulfide (H2S) gas

formation.

Routine monitoring of:

» Static geochemistry of pit wallrock samples from active mining benches during operation to

confirm that the potential geochemical risk associated with the pit wallrock material remains low. If

a change in the geochemical risk classification of the wallrock is observed, a geochemistry

management plan should be prepared; and

» Water quality in the Mine Pit sumps. Monitoring of water quality during operation will inform the

potential requirement and method for water treatment, if required.

Monitoring of pit inflow water quality during operation will inform whether water treatment will be

required post-closure.


Mine Pit –Pit Lake Development

When mining is complete, Mine Pit dewatering will be ceased and pit inflow will contribute to the formation

of a Mine Pit lake, which may overflow within 20 years of the end of mining. Modelling shows the potential

for slightly elevated salinity which will be treated with TMF seepage if required, and if pit lake overflow occurs.

Waste Rock Disposal

To further reduce the potential low level water quality impacts related to the geotechnical / geochemical

stability, progressive rehabilitation and revegetation of the WRD batters during operation to assist with the

stabilisation of the WRD surface sediments.

Waste Rock Dump

The WRD will be a stable long term structure that will be progressively rehabilitated throughout operation

and finally rehabilitated to a self-sustaining natural ecosystem at the conclusion of mining (whilst processing

continues). The detailed rehabilitation objectives and rehabilitation plan is provided in the Rehabilitation and Conceptual Mine Closure Plan (Volume E). WRD design and construction will allow the outer batter

face to be rehabilitated during its construction. Upon decommissioning, the batters and top surface of the

WRD will be graded to provide a uniform slope, with contours diverting water to controlled drainage

structures and ultimately Badalla Creek. Geotextile / erosion control blankets (e.g. jute netting) and topsoil

will be applied and the WRD planted with native vegetation to minimise erosion.

The geochemical risk associated with the waste rock material is very low. Drainage from the WRD will report

to the TMF prior to discharge from site. The management of the water quality draining the WRD post-closure

will include, depending on the solute loads generated, an engineered passive anaerobic wetland system

which may be effective in lowering sulfate salinity and metal concentrations in the WRD leachate post-

closure, if required.

Ore Stockpile

To minimise potential for erosion and sedimentation during decommissioning and closure, the topsoil will be

ripped to a depth of approximately 1 m, graded to match the contours and drainage pattern of adjacent

topography, and planted with native vegetation.

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FINAL 9-14


The Mine Pit will be a permanent feature in the landscape. The Company has committed to monitor the

water quality in the Mine Pit, Badalla Creek and the Gambia River to ensure that potential discharge from the

pit lake, post-closure, meets Project discharge requirements and ambient water quality requirements.

Implementation of the prescribed management and mitigation measures for the WRD will effectively avoid

potential water quality impacts during operation (i.e. sediment transport beyond the Project PDA, AMD, NMD,

etc.). Rehabilitation of the WRD at decommissioning and processing all ore from stockpiles (and

rehabilitating / revegetating stockpile areas) is expected to minimise the potential for residual impacts.

Monitoring of surface and groundwater post-closure will be implemented to determine whether additional

measures are required to avoid post-closure impacts to water quality.

To avoid potential safety risks at the Mine Pit, an earthen bund will be constructed around the perimeter,

access blocked, and warning signage erected at key access points to warn people of the potential safety risk

of entering the facility.

The key expected residual impacts related to Mine Pit and waste rock disposal under normal operating

conditions, and their overall significance for each Project phase, are summarised in Table 9-5. Monitoring will

be required over the mine life to confirm the residual impact predictions, and allow management measures

to be adapted accordingly.

Table 9-5 Summary of expected Mine Pit and waste rock disposal pre-mitigation and residual impacts

Receptor / Value Expected Pre-Mitigation Impact

Significance


Key Expected Residual Impacts and Overall Impact

Significance


Waste Rock Geochemistry

MINOR

WRD in controlled catchment

Stormwater and sediment treatment

Monitoring

NEGLIGIBLE

Salinity generation from WRD

Mine Pit water quality MODERATE

Dewatering and runoff water collected in sediment basin to settle solids

Dewatering sent to process water and TMF

NEGLIGIBLE

Elevated solids and salinity

Operation


MINOR



Runoff and seepage collected in TMF

Monitoring

NEGLIGIBLE

Salinity generation from WRD


Dewatering and runoff water collected in sediment basin to settle solids

Dewatering sent to process water and TMF

NEGLIGIBLE

Elevated solids and salinity

Ore Stockpile erosion and water quality

MINOR

Sediment control structures

Runoff contained in TMF catchment

NEGLIGIBLE

Salinity generation from Ore



MINOR



Seepage treatment below TMF if

NEGLIGIBLE

Potential salinity generation from WRD

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FINAL 9-15


Significance



Significance

required

Monitoring

Revegetation of WRD


Operation of pit lake

Bunding to prevent access

Pit lake may develop overflow

Monitoring/modelling of inflow quantity/quality

Possible wetland treatment of overflow

Management to minimise H2S

Monitoring

MINOR

Potential elevated salinity

Ore Stockpile erosion and water quality

MINOR

Site rehabilitation and revegetation

Sediment control structures

Drainage lines re-established and revegetated

NEGLIGIBLE

Suspended sediment generation until grass revegetation closes

9.3 Tailings Disposal



Tailings disposal / impacts will not occur during Project construction.

Operation

Approximately 225 tonnes per hour of solids process tailings and 225 tonnes per hour of process water will

be generated from the Process Plant. Tailings will be disposed of in the TMF. Approximately 50% of the

process water will be entrained in saturated tailings in the TMF, while the remaining will be recovered and

returned to the Process Plant for re-use.

TMF surface water may have elevated concentrations of cyanide from ore processing, elevated salinity,

dissolved metals, and elevated nutrients (breakdown products of cyanide). Further, the tailings are a potential

(though unlikely) source of Acid and Metalliferous Drainage (AMD) or Neutral Metalliferous Drainage (NMD),

as the geochemical risk associated with the tailings material is low. Cyanide destruction, via the INCO (SO2 +

air) process, will be implemented to ensure weak acid dissociable (WAD) cyanide concentrations are below 50

mg/L in the TMF. Tailings piped to the TMF may have elevated concentrations of cyanide, elevated salinity,

heavy metals, and nutrients that are an additional potential source for surface or groundwater contamination

if the piping network is ruptured.

The potential AMD risk associated with the tailings material is low. Approximately 87% of the tailings samples

analysed were non-acid forming and all of the basalt tailings samples analysed were non-acid forming. As a

result of the geochemical / sulfide oxidation processes (i.e. not accounting for process water chemistry),

tailings pore water / supernatant and seepage is expected to be near neutral to slightly alkaline, with low

levels of sulfate salinity and very low dissolved metal (e.g. arsenic, chromium ± manganese, as a result of the

dissolution of carbonate minerals) concentrations.

A small proportion of the ore / tailings samples (~13%) were classified as potentially acid forming (PAF).

However, it is likely that the ore / tailings material is mostly NAF. Routine monitoring and analysis of tailings

Mako Gold Project


FINAL 9-16

static geochemistry on samples collected from the tailings thickener underflow during operation will be

conducted to confirm that the geochemical risk associated with the tailings material remains low.

The TMF has been designed with a composite basin liner system, with an engineered soil liner over the entire

basin, constructed primarily with re-worked in-situ material. A HDPE geomembrane liner will be installed over

the southern TMF area to cover the extent of the average TMF supernatant pond to limit seepage and

percolation from the TMF.

All drainage pipes will be directed to an HDPE lined seepage collection pond located downstream of the TMF

embankment. At the inlet to the pond, the flow from the drainage pipes will go over a v-notch weir or similar

to enable measurement of individual flows and samples to be taken. The seepage collection pond will be

provided with a pump and pipeline to allow water to be pumped back into the TMF.

The TMF facility has been designed to avoid discharge to receiving waters during Project operation.

The TMF is designed to contain a 1 in 100 year 72 hour storm event and a 1 in 100 year 12 month wet rainfall

sequence (Knight Piesold, 2015d). Stormwater diversion channels will divert water from the catchment

around the facility to limit TMF input to that from processing and direct precipitation.


Upon Project decommissioning / closure, the TMF will be rehabilitated and surface water from the facility (as

well as inputs from the WRD and Mine Pit overflow (if applicable) will discharge from a constructed TMF

spillway into Badalla Creek downstream of the facility, a small tributary of the Gambia River. Seepage

monitoring during operation will be used to determine if TMF seepage post closure will require treatment.


Avoidance

The TMF facility has been designed to avoid discharge to receiving waters during Project operation.

The TMF is designed to contain a 1 in 100 year 72 hour storm event and a 1 in 100 year 12 month wet rainfall

sequence, with an additional 1 m contingency freeboard (Knight Piesold, 2015d). Shallow and deep

groundwater monitoring bores will be installed downgradient of the TMF to detect seepage water quality

and quantity.

Geochemistry / water quality

The TMF has been designed with a composite basin liner system, with an engineered soil liner over the entire

basin, constructed primarily from re-worked in-situ material. A HDPE geomembrane liner will be installed

over the southern TMF area to cover the extent of the average TMF supernatant pond and limit seepage of

water from the TMF. The TMF facility has been designed to avoid discharge to receiving waters during Project

operation.

During operation, monitoring and analysis of tailings static geochemistry on samples collected from the

tailings thickener underflow will be conducted to confirm that the geochemical risk associated with the

tailings material remains low. TMF liquor and supernatant pond quality and groundwater quality in

monitoring piezometers downstream of the TMF will also be monitored routinely during operation.

Salinity and metals

Supernatant water will be contained within the TMF (or the seepage collection pond) for recycling as Process

water. TMF water will not discharge to the receiving environment under normal operating conditions.

Based on the Knight Piesold (2015) water balance model, arsenic levels in the TMF supernatant pond are likely

to be above the IFC Effluent discharge standard of 0.1 mg/l at all times and above 1 mg/l at the end of the dry

season (25~73% of the time) due to evaporative concentration when supernatant pond levels are at their

lowest.

Mako Gold Project


FINAL 9-17

Water quality in the supernatant pond will be of better quality during the wet season. At the end of the dry

season, water quality within the TMF will be poor with high salinity and high arsenic and copper levels, lead

and zinc levels.

Access to the TMF facility will be restricted by the use of fencing, to prevent poor quality TMF supernatant

water from being consumed by local wildlife during the operation of the TMF (see Figure 9-1). In any case,

elevated salinity levels are expected to make the supernatant water unpalatable for local species.

Minimisation

Cyanide

Weak acid dissociable (WAD) cyanide concentrations in the TMF will be below 50 ppm to comply with the

International Cyanide Management Code (ICMC) Guidelines. Destruction of residual cyanide from the CIL

circuit in the Process Plant down to < 50ppm will occur via air / SO2 process utilising reagents (sodium

metabisulfite, sodium hydroxide and copper sulphate). Recycling of process water from the TMF will recover a

portion of the residual cyanide from spent leach, reducing cyanide input.


The TMF surface will be rehabilitated via placement of 300 mm thick sub-base material and 150 mm thick

topsoil on all but the rock-line drainage channels (approximately 25% of the TMF surface area). The TMF will

be revegetated with native species (Shrub savannah vegetative community). The riparian corridor of Badalla

Creek / TMF discharge channel will be planted with native shrub and tree species to stabilise the landform.

Upon Project closure, runoff from the surrounding catchment and rehabilitated WRD surface, and pit overflow

will be directed through rock-line channels to the rehabilitated TMF. The TMF spillway constructed across the

low ridge on the west abutment of the TMF embankment (refer to Project Description, Chapter 4) will

discharge surface water from the WRD, TMF, and Pit Lake (when applicable). TMF supernatant water (and WRD

/ Pit wallrock geochemistry) will be monitored throughout operation, immediately prior to Project

decommissioning, and post-closure. Surface water / TMF supernatant water will be treated (as required) to

ensure compliance with discharge guidelines (GRS, 2002; IFC, 2007) and ambient water quality guidelines

(USEPA, 2009 and EU, 2006), prior to commencement of discharge to the spillway.

Initial modelling of TMF seepage during closure predicts that seepage will most likely be variable depending

on the season and will be low in volume relative to surface water flows in the Badalla Creek. Surface water

quality modelling indicates that seepage water of poor quality may influence the water quality in Badalla

Creek during low flow periods, and when the creek ceases to flow and creek pools are concentrating during

the dry season. Treatment of TMF seepage water, if required, could include measures such as:

Metal removal with the addition of an iron based compound to allow metal adsorption;

Wetland treatment of metalliferous seepage;

Shallow groundwater interception of groundwater prior to entering Badalla Creek and return for

treatment; and

Capture in designed storage pond or subsurface drain (e.g. drainage cells) to meet dilution

requirements with no discharge until sufficient flow develops in the Badalla Creek.

Ongoing post-closure water quality monitoring will be conducted at the Badalla Creek and Gambia River

compliance sites, to ensure water flowing from the rehabilitated TMF (and WRD) and any treatment system if

required, is compliant with applicable guidelines. Shallow and deep groundwater monitoring bores will be

installed below the TMF embankment and downstream of the TMF to monitor groundwater quality during

TMF operation. Analysis and modelling of surface water quality can then be used to determine if the seepage

requires additional treatment, based on the findings of the operational surface and groundwater monitoring

programs.

Mako Gold Project


FINAL 9-18


Implementation of the prescribed management and mitigation measures for the TMF will effectively avoid

potential water quality impacts during operation (i.e. sediment transport beyond the Project PDA, AMD, NMD,

etc.) via avoidance of discharge from the PDA.

Rehabilitation of the TMF at decommissioning, including treatment of the TMF supernatant pond at

decommissioning, is expected to minimise the potential for residual impacts. Monitoring of surface and

groundwater during operation and post-closure will be implemented to determine whether additional

measures are required to avoid post-closure impacts to water quality.

Treatment of TMF seepage, if required, will enable the Badalla Creek to meet ambient water quality standards

(USEPA, 2009 and EU, 2006) during the post closure period.

The key expected residual impacts related to tailings disposal under normal operating conditions, and their

overall significance for each Project phase, are summarised in Table 9-6. Monitoring will be required over the

mine life to confirm the residual impact predictions, and allow management measures to be adapted

accordingly.

Table 9-6 Summary of expected tailings disposal pre-mitigation and residual Impacts


Significance




TMF water quality MINOR

TMF in controlled catchment


Monitoring

NEGLIGIBLE

Suspended solids from construction disturbance

Operation

TMF geochemistry and water quality

MODERATE

TMF liner and seepage collection

Monitoring of tails static geochemistry

Treatment for CN, possibly As reduction

Exclusion zone and site fencing to prevent access

MINOR

Infrequent bird life contact with poor

quality water

TMF seepage -groundwater quality

MODERATE

TMF liner and seepage collection system

Down gradient groundwater monitoring bores

Treatment

NEGLIGIBLE

Salinity generation from seepage

TMF emergency discharge/Overflow

MAJOR

Freeboard design of TMF to incorporate 1:100 ARI events through the life of the mine

Overflow channel designed for peak flow during 1:100 ARI event

MINOR

Overflow unlikely during mine operation

Dilution of overflow expected in surrounding storm/flood waters


TMF geochemistry and water quality

MODERATE

Treatment of final TMF supernatant

Rehabilitation and revegetation of TMF

Seepage rate limited by catch and release cover

MINOR

Treatment may be required if salinity and metals elevated during low flow/cease to flow events in Badalla Creek

Mako Gold Project


FINAL 9-19


Significance



TMF seepage -groundwater quality

MODERATE

Down gradient groundwater monitoring bore

Seepage collection and treatment (if required)

Possible dilution with pit lake overflow water

MINOR

Treatment may be required if salinity and metals elevated during low flow/cease to flow events in Badalla Creek

9.4 Hydrology


The PDA and Access Corridor are located in the upper Badalla Valley and western Wayako Valley catchments.

All of the sub-catchments form small tributaries to the Gambia River which is approximately 5 km to the

south of the proposed Mine Pit. The Petowal ridgeline is 400 m in elevation and forms the western most

catchment boundary for Badalla Valley, and the northwest catchment boundary for Wayako Valley. To the

west of the ridgeline, three small unnamed streams that are tributaries of the Kelendourou Creek, flow into

the PNNK which is approximately 1-2 km to the west of the PDA. These tributaries have very small areas of

catchment in the PDA, all of which is confined to the proposed Mine Pit.

The primary Project affected watercourses requiring assessment include (Figure 9-2):

Badalla Creek, an ephemeral first order tributary of the Gambia River, where the majority of the

proposed Project infrastructure would be constructed (in its catchment);

Kobokou Creek, an ephemeral first order tributary of the Gambia River, the upper catchment of which

will be impounded by the WSD;

Kelendourou Creek, a second order tributary of the Gambia River which captures water from

ephemeral tributaries with small catchments in the PDA (flows to the PNNK); and

Gambia River (the major watercourse in the region, also flowing through the PNNK).

Mako Gold Project


FINAL 9-20

Figure 9-2 Mako Gold Project Development Area Hydrology

Mako Gold Project


FINAL 9-21

The PDA is primarily located in the upper Badalla Valley, with minor overlap into the western Wayako Valley

and Kelendourou catchments. Catchment slopes in the PDA vary from steep (10 to 20%) at ridgelines, 3-5% in

the mid catchment areas and flattening to less than 3% towards lower catchment areas as streams discharge

to the Gambia River or Kelendourou Creek. The stream slope of the Gambia River itself is slight at

approximately 0.1% within the reaches in the vicinity of the PDA.

Stream gauging stations (refer to Figure 9-3) were installed on Badalla Creek draining the Petowal deposit

(SW3); Bowoyoto Creek (SW2), which drains the Wayako valley; and the Kobokou Creek (WSD1) draining the

proposed WSD, to monitor flow in these ephemeral creeks during the wet season of 2014. Gambia River stage

height has been measured twice daily by the Direction des Parcs Nationaux at the Gambia River Mako Station

(SW8) to determine the flow (m3/s) of the Gambia River. A height - discharge rating curve for the Gambia

River at Mako has been established using data collected between 1976 and 1987 by Institut Français de

Recherche Scientifique pour le Developpement en Cooperation (ORSTOM) and Organisation pour la Mise en

Valeur du Fleuve Gambie (OMVG) (Lamagat et al., 1990). Recent data were added to the rating curve between

1998 and 2000 by the Water Brigade of Tambacounda to validate the original stage - discharge rating curve.

The current rating curve is gauged to maximum flow of approximately 700 m3/s.

Operation

The assessment of potential impacts on the hydrology of local streams was undertaken using modelling to

support the limited stream flow data available for the Project area. Hydrologic modelling was undertaken

using the US EPA SWMM modelling system (USEPA 2008), using an initial and continuing loss model, based on

observations of the flow records collected in the area, and local climate patterns. The predicted surface water

hydrological impacts in the Operation Phase are shown in Figure 9-4.

Badalla Creek

Pre-mining peak flow for Badalla Creek (median year) is estimated (modelled) to be approximately 5.2 m3/s.

As discharge from Project facilities into Badalla Creek will be prohibited during operation (to avoid potential

water quality impacts), Badalla Creek peak flow for the Project operational phase will decrease (predicted to

be approximately 2.9 m3/s). The change in annual flow in the Badalla Creek catchment from pre-mining to

the operational phase is a reduction in flow of approximately 48%, while peak flows are similarly reduced by

approximately 45% (refer to Table 9-7).

The modelling point (refer to Figure 9-3) for this assessment is located 600 m to the north of the confluence

of the Badalla Creek and Gambia River.

Table 9-7 Hydrograph analysis for Badalla Creek, Pre-mining and Operation Phase

Hydrograph Analysis Pre-Mining Operation Change (%)

Annual flow (ML) 1564 809 -48

Peak Flow (m3/s) 5.2 2.9 -45

95% flow (m3/s) 0.6 0.3 -48

Kobokou Creek

The WSD embankment will impound the upper reach of Kobokou Creek, though a horizontal blanket drain in

the spine of the valley will maintain drained conditions downstream of the WSD embankment area during

operation and water from the catchment downstream of the WSD will continue to flow to the natural

channel.

The WSD is predicted to capture approximately 92 ML of Kobokou Creek streamflow per annum. The

predicted peak flow velocity in Kobokou Creek is approximately 1.2 m3/s pre-mining and 0.75 m3/s after the

WSD is constructed, a decrease of 66% and 64% annual and peak flow, respectively. Model outputs are based

on a point approximately 300 m to the north of the Gambia / Kobokou confluence. Surface flow will be

significantly decreased during the rainy season (south of the WSD) during mine operation. Table 9-8 shows

the hydrograph analysis for Kobokou Creek.

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FINAL 9-22

Table 9-8 Hydrograph analysis for Kobokou Creek, Pre-mining and Operation Phase


Annual flow (ML) 140 48 -66

Peak Flow (m3/s) 0.7 0.3 -64

95% flow (m3/s) 0.0 0.0 0

Kelendourou Creek

Three small Kelendourou Creek tributaries will be affected by small catchment area losses to the Mine Pit

during operation (and post-closure). Modelling of hydrological impacts on these tributaries is presented to

assess potential changes to hydrological regimes entering the Niokolo-Koba National Park. The small

difference in flow is observable only at the tip of the flow hydrograph peak flows (~1.7%), due to the relatively

small catchment areas being diverted to the Mine Pit.

Statistical analysis of the Kelendourou tributaries hydrographs before mining and in the operational phase is

provided in Table 9-9. The results predict that catchment flow reduction in the Kelendourou tributaries is very

low, at approximately 1.7% of annual flow volumes and with no measurable reductions in peak flow or flow

duration. There is negligible change in the natural flow hydrograph predicted due to Mine operation.

Table 9-9 Hydrograph analysis for Kelendourou Creek, Pre-mining and Operation Phase


Annual flow (ML) 3862 3797 -1.7

Peak Flow (m3/s) 3.5 3.5 0.0

95% flow (m3/s) 1.6 1.6 0.0

Figure 9-3 Predicted Pre-mining and Operation / Post Closure flow in Kelendourou Tributaries

The flows of the three Kelendourou Creek tributaries whose catchments are slightly intercepted by the Mako

Gold Project represent a very small proportion of flow entering the Kelendourou system. As a result,

graphical analysis of change in Kelendourou Creek flow for pre-mining to operational phases is not

detectable on a visual hydrograph.

0

0.5

1

1.5

2

2.5

3

3.5

4

21

-Ap

r-0

1

28

-Ap

r-0

1

05

-May

-01

12

-May

-01

19

-May

-01

26

-May

-01

02

-Ju

n-0

1

09

-Ju

n-0

1

16

-Ju

n-0

1

23

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n-0

1

30

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l-0

1

14

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28

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g-0

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18

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g-0

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25

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-Se

p-0

1

08

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p-0

1

15

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p-0

1

22

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p-0

1

29

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13

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20

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27

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03

-No

v-0

1

Flo

w (

m3

/s)

Premining Operations

Mako Gold Project


FINAL 9-23

Gambia River

The Mako Gold Project will abstract approximately 770 ML of water per year from the Gambia River during

the rainy season months for storage in the Water Supply Dam (and utilisation as Process water, dust

suppression, and camp supply) (Toro Gold, 2015c).

During a relatively dry year, total flow in the Gambia is approximately 1,760,000 ML and approximately

2,888,000 ML during the median year. The total annual supply of mine water proposed during a dry year

represents 0.04% of the Gambia River annual flow and 0.03% of the annual Gambia River flow during the

median year.

Analysis of the impact of water supply pumping on the Gambia River daily hydrograph during dry years show

that during peak flows the rate of abstraction is approximately 0.015% of instantaneous river flow. This is

unlikely to cause any impacts to the aquatic ecosystem or downstream users, but as each dry season may

display different characteristics, it is recommended that daily pumping data be compared with daily flow in

the Gambia River to prevent over-abstraction in the early dry season flow. Project water abstraction will

represent a higher percentage of the instantaneous river flow at the beginning and the end of the wet

season, when river discharge is low.

Peak flow from Kelendourou Creek, Badalla Creek and Kobokou Creek represent a very small fraction of

Gambia River flow (i.e. Kelendourou Creek contributes approximately 1.5% to the Gambia in the median year).

The very small reduction in flow from prohibiting discharge from much of the Badalla and Kobokou

catchments and a negligible flow reduction in Kelendourou Creek was not detectable during the conduct of

surface water modelling for this Project. The flow reduction statistics from water supply pumping and mine

operation is shown in Table 9-10.

Table 9-10 Hydrograph analysis for the Gambia River, Pre-mining and Operation Phase


Annual flow (ML) 2,888,234 2,886,602 -0.06

Peak Flow (m3/s) 728.81 728.76 -0.01

95% flow (m3/s) 445.63 445.54 -0.02

80% flow (m3/s) 153.08 153.03 -0.03

Median flow (m3/s) 15.20 15.15 -0.33

25% flow (m3/s) 1.70 1.70 0.00

Minimum flow (m3/s) 0.00 0.00 0.00

Most change in flow conditions from pre-mining to operation is in the range of less than 0.1% of total flow in

the Gambia River. The only percentile not meeting this level of impact was the median flow, which showed a

slightly higher 0.33% flow reduction. This is considered to be a very Minor to Negligible reduction in overall

flow in the Gambia River and the impact to downstream users and aquatic ecosystems is also considered to

be Negligible.


The hydrology for the Project affected streams will gradually return to baseline status, including flow volume,

post-closure. Discharge for Badalla Creek and Kobokou Creek will resume near natural character. The

catchments for Badalla Creek and Kelendourou Creeks (to a lesser extent) will be slightly reduced, given the

Mine Pit void will remain following closure. This potential water loss may be offset by the development of the

mining pit lake which is predicted to deliver additional flow to Badalla Creek post closure (after 2046) for

three months with a peak flow of approximately 0.04 m3/s. Peak flow in the Badalla Creek is predicted to be

1.2 m3/s, during this period so pit lake overflow, if occurring will be a small component, approximately 3%, of

total flow. While this is a negligible peak flow increase, and represents very low risk to the ecosystem or local

Mako Gold Project


FINAL 9-24

communities, it is likely that the creek may flow continuously during this period rather than ceasing to flow

between rainfall events.

The resulting impacts to surface water hydrology may include:

Approximately 1.7% less flow in the three Project affected Kelendourou tributaries during peak flow;

and

Potentially slower flow due to ponding of Badalla Creek on the flat TMF surface.

A post-closure water balance will be required in order to quantify potential hydrology impacts post-closure.

Stream flow gauging stations developed during the project can be used to measure actual flow regime

change post closure to determine if any further corrective action is required.

Predicted post-closure impact levels on surface water hydrology are shown in Figure 9-5.

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Figure 9-4 Operation Phase surface water hydrology impacts

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Figure 9-5 Post-Closure surface water hydrology impacts

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FINAL 9-27


Avoidance

Protection of Project receiving waters, which ultimately flow to the Niokolo-Koba National Park has been

considered a very important objective throughout Mako Gold Project design, with several major design

changes resulting to avoid potential environmental impacts from the Project. These are described in Chapter

5.

The principal management measure for avoiding impacts to hydrology is the siting of the majority of Project

infrastructure in Badalla Valley (one small catchment), to limit the extent of potentially significant impacts to

one ephemeral stream. Additional avoidance techniques include:

Minimised catchment footprint for Mine Pit and operation; and

Diversion of clean stormwater around mine structures to the natural catchment.

Minimisation

Badalla Creek

Surface water flowing from upstream of Project facilities will be diverted around the Project Footprint for

discharge into the TMF. The small drainage area around the Mine Pit will be allowed to drain in a controlled

manner into the pit, with no engineered surface water channels required around the pit itself due to the

topographical layout. Peripheral surface water drainage channels will be constructed at the perimeter of the

WRD, with open channels designed to collect surface water runoff originating from the waste rock material.

These channels will redirect the intercepted water into the TMF. Surface water hydrology for Badalla Creek will

be significantly reduced during operation due to the Project’s ‘zero discharge’ design for this catchment (to

protect water quality), which will alter stream flow during the rainy season for this ephemeral stream. The

zero discharge measure prevents impacts to water quality but also limits additional management measures

to offset flow reduction for this stream; the PDA water balance indicates the Project is in deficit, which means

no additional water sources are available to supplement environmental flows. Badalla Creek does not contain

any identified sensitive aquatic ecosystem components such as springs or groundwater dependent

ecosystems, and so therefore reduced streamflow is acceptable during the period of mining.

Badalla Creek flow will resume to a near natural response post-closure as the TMF spillway will be configured

to convey surface water from the Project Footprint back to the natural channel.

Kobokou Creek

A horizontal blanket drain in the spine of the valley will maintain drained conditions downstream of the WSD

embankment area during operation. Water from the catchment downstream of the WSD will continue to flow

to the natural channel. Kobokou Creek does not contain any identified sensitive aquatic ecosystem

components such as springs or groundwater dependent ecosystems, and so therefore reduced streamflow is

acceptable during the period of mining.

Kelendourou Creek

Three small Kelendourou Creek tributaries will be affected by small catchment area losses to the Mine Pit

during the operational mining phase. The orientation of the Mine Pit has been designed to minimise impacts

to stream hydrology for the Kelendourou Creek and the Niokolo-Koba National Park.

As hydrologic impacts to this stream are Negligible, management measures are implemented to protect its

water quality only (i.e. surface water from the disturbed portion of the Kelendourou catchment will be

diverted to the Badalla Creek catchment to prevent sediment input to Kelendourou Creek).

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FINAL 9-28

Gambia River

Abstraction from the Gambia will occur during high flow months from July – December, pending the onset of

rains. Abstraction will not commence until the Gambia River flows reach adequate volume to minimise

impacts to the river and the associated aquatic habitat.

It is proposed to establish a minimum environmental flow requirement of 5 m3/s in the Gambia River before

abstraction can commence. In addition to the minimum environmental flow requirement, a maximum take of

3% of instantaneous Gambia River flow is proposed, to further reduce any potential impacts on downstream

users or the aquatic ecosystem to as low as reasonably practical.

Most years the Gambia River ceases flow in the dry season for several months. Flow commences in the small

tributaries (such as Badalla Creek) of the Gambia River prior to wet season flow developing, in the Gambia

River. Surface water quality modelling indicated that management of stormwater water quality during these

first flush periods is therefore of importance as there will be little or no potential for dilution in the Gambia

River, even though the Badalla Creek may be at nearly peak flow during rainfall periods.


Badalla Creek

Badalla Creek flow will resume to a near natural response post-closure as the TMF spillway will be configured

to convey surface water from the Project Footprint back to the natural channel.

Kobokou Creek

Post-closure, the WSD embankment will be removed and the channel morphology rehabilitated to allow the

pre-project flow regime to continue.

Kelendourou Creek

As hydrologic impacts to this stream are Negligible, no rehabilitation measures are required.

Gambia River

Water will not be abstracted from the Gambia River following Project decommissioning. No rehabilitation

measures are required.

Enhancement

If Mine Pit lake overflows do occur post closure (~August 2045), there is the possibility to provide some

additional water to maintain dilution and suitable water quality in Badalla Creek during the post closure

period if required. This could be particularly useful during low flows or at the beginning or end of the dry

season.


Impacts to surface water hydrology during pre-construction / construction and operation will be Negligible

to Moderate, depending on the watercourse.

The hydrology of Badalla and Kobokou Creek will be significantly impacted during the rainy season, with flow

restricted to that stemming from the catchments downslope of the Project Footprint. Impacts will be

restricted to the lower reaches of Badalla and Kobokou Creeks. The morphology of the Badalla Creek will be

altered and all water flow from the upper reaches of the creek will be impounded in the TMF, while The flow

of Kobokou Creek will be impounded in the WSD when the dam embankment .

Impacts to regional hydrology (e.g. the Gambia River) will be Negligible. Water will be abstracted from the

Gambia River during the wet season and stored in the WSD as make-up water for operation of the Process

Plant. Water abstraction from the Gambia River during the rainy season will not impact the river. The total

volume of water abstracted for the Project is less than 0.04% of the total Gambia River flow during a dry year

Mako Gold Project


FINAL 9-29

and less than 0.03% during the median flow year. Impacts to the hydrology of Kelendourou Creek will be

Negligible during operations.

Post-closure impacts to surface water in the Project Area are expected to be Negligible.

The key expected residual impacts on hydrology under normal operating conditions, and their overall

significance for each Project phase, are summarised in Table 9-11.

Monitoring will be required over the mine life to confirm the predictions, and allow management measures to

be adapted accordingly. The Company has established a number of hydrology monitoring stations around

the Mako Project area which are monitored on an ongoing basis. Stream gauges will be used to measure

surface flow and stream height. Data will be collected routinely (e.g. daily or monthly) depending on the

location. Implementation and management will be the responsibility of the Company’s Environment

Department. Further details regarding hydrology monitoring are provided in the ESMMP (refer to Volume C).

Table 9-11 Summary of key expected pre-mitigation impacts, mitigation measures and residual impacts on

hydrology for each Project phase


Significance

Key Management & Mitigation Measures Key Expected Residual Impacts and Overall Impact Significance


Impact to hydrology of Badalla Creek

MODERATE

Surface water flowing from upstream of

Project facilities will be discharged into the

TMF.

MODERATE

Stream flow will be reduced.

Impact to hydrology of Kobokou Creek

MODERATE

A horizontal blanket drain in the spine of the

valley will maintain drained conditions

downstream of the WSD embankment area.

MODERATE


Impact to hydrology of Kelendourou

NEGLIGIBLE

None required NEGLIGIBLE

No detectable impact to flow

Impact to hydrology of Gambia River

NEGLIGIBLE



Operation


MODERATE

Surface water flowing from upstream of

Project facilities will be discharged into the

TMF

MODERATE



MODERATE

A horizontal blanket drain in the spine of the

valley will maintain drained conditions

downstream of the WSD embankment area

during operation.

MODERATE



NEGLIGIBLE




NEGLIGIBLE

Minimum environmental flow requirement of

5 m3/s in the Gambia River before abstraction

can commence.

Maximum take of 3% of Gambia River flow

NEGLIGIBLE


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FINAL 9-30


Significance




MODERATE

Configure TMF spillway to convey surface

water from the Project Footprint back to the

natural channel at closure.

MINOR

Badalla Creek may flow continuously if the pit lake overflow develops


MODERATE

Remove WSD embankment and rehabilitate the channel morphology post-closure

MINOR

Stream discharge may reduce due to vegetation regrowth


NEGLIGIBLE




NEGLIGIBLE



9.5 Hydrogeology


Groundwater flow in the Project region appears to be through fractured zones in low permeability bedrock.

Groundwater in the overlying weathered zone and bedrock is likely a single aquifer, with groundwater

flowing towards topographic depressions and mirroring topography. Locally, the geology of the deposit

broadly consists of a felsic volcanic unit that is bounded by basaltic volcanics. The felsic unit is discontinuous,

decreasing in thickness and eventually disappearing to the northeast. The weathering profile generally

comprises laterite / saprolites and saprock (transitional) materials from host rock (SRK, 2015). The weathering

profile at the Petowal deposit is expected to be largely unsaturated during the wet and dry seasons. The fresh

basement represents the only substantially saturated aquifer unit and is only permeable where fractured. The

groundwater elevations and flow directions provide evidence for a groundwater system that drains either

into local tributaries of the Gambia River or directly to the river itself. Groundwater transport in the fresh

basement is primarily dipping to the northwest to southwest via fractures. Inflow zones (to the pit) may be

present across the entire depth of mining either by single, discrete fractures or by fracture zones. The bulk

hydraulic conductivity of the rock mass ranges between 7.62 E-2 and 7.40 E-5 m/d, with a geometric mean of

1.66 E-3 m/d. The estimated recharge (between 30 to 126 mm/yr based on two analysis methods provides an

estimated recharge equivalent to approximately 3 – 10% of total annual rainfall (SRK, 2015).

Based upon hydrogeological modelling conducted for the Project (SRK, 2015), groundwater inflow into the

Mine Pit is effectively zero for the first eight months of mining until the Pit reaches the water table. Inflows

rise to a maximum of 259 m3/d (3L/s) by the end of mining.

Structural modelling (SRK, 2015) indicates the predominance of small-scale discontinuous faults in the Mine

Pit area which are typically characterised by limited storage of groundwater and are therefore not likely to be

significant in terms of long-term (base-case) groundwater inflows. However, short-term inflows associated

with such structures may occur where a fault of significant fracture is intersected following blasting.

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FINAL 9-31

Figure 9-6 Base-case and Maximum Short-term Groundwater Inflow to the Mine Pit from Numerical Modelling

(Source: SRK, 2015)

Surface water inflow as a result of direct rainfall within the Mine Pit footprint / small catchment ranges from

0.02 km2 (year 1) to 0.27 km2 (year 9) (SRK, 2015). It is estimated that approximately 30% of the direct rainfall

will be lost due to a combination of evaporation and storage. Figure 9-7 estimates the total inflow of water

(groundwater + surface water) that will be abstracted from the Mine Pit during operation.

Figure 9-7 Total (groundwater and direct precipitation) Minimum and Maximum inflows for the Life of Mine

(Source: SRK 2015).

Mine Pit

Development of the Mine Pit will generate a cone of depression whereby some of the southeast moving

groundwater that recharges the aquifer at lower elevations (e.g. Badalla Creek and Gambia River Valleys) will

move into the pit void, where it will be pumped to the Process Plant or WSD. The cone of depression has been

Mako Gold Project


FINAL 9-32

estimated to extend to a maximum of 900 m from the pit edge, which would not impact known water supply

boreholes used by local communities (SRK, 2015).

Initial modelling of the development of the mining pit lake predicts the delivery of additional flow to Badalla

Creek post closure (after 2046) for three months each wet season with a peak flow of approximately 0.04 m3/s,

while peak flow in the Badalla Creek is predicted to be 1.2 m3/s, approximately 3% of total flow. While this is a

negligible peak flow increase, and represents very low risk to the ecosystem or local communities, it is likely

that the creek may flow continuously during this period rather than ceasing to flow between rainfall events.

Salinity contained in local groundwater is predicted to concentrate slowly in the pit lake until the estimated

lake overflow 20 years after the cessation of pit dewatering. Pit lake overflows may require treatment during

the post closure period.

Initial modelling of the Mine Pit lake allows for the estimation of groundwater loss. Pit lake losses of the post

mining pit lake (when full) are estimated to be in the order of 270,000 m3/year due to evaporation and

250,000 m3/year due to the pit lake overflow. Annual recharge of the groundwater upgradient of the Mine Pit

(~65 ha) is estimated to be in the order of 90,000 to 200,000 m3/year. Annual rainfall into the pit lake is in the

order of 450,000m3. Annual losses of groundwater in the Badalla Creek aquifers due to the pit lake are

extremely low, estimated to in the order of 20,000 m3/year or approximately 1 x 10-5 %.

Modelling of pit lake development upon cessation of dewatering will be required using the regional

groundwater model in order to determine the potential for discharge of water from the Mine Pit post-closure.

This modelling will be undertaken during the Operation Phase using the groundwater inflow and quality data

from the pit dewatering systems.


Minimisation

The cone of depression cannot be mitigated during operation. Water from the dewatering of the Mine Pit

during operation will be maintained on-site for re-use in the Process Plant, with any excess water to be

pumped to the WSD. Post-closure, surface water in excess of the Mine Pit lake storage capacity will be

directed via rock-line channel to Badalla Creek, a first order tributary of the Gambia River.

Enhancement

The following actions are recommended to enhance understanding of hydrogeology in the Mine Pit area

during operation:

Expand the Petowal groundwater monitoring network by converting core holes into sealed monitoring

piezometers. Core-holes that reside outside of the planned pit perimeter should be selected. These

piezometers would be used for water quality monitoring in addition to hydrogeology monitoring;

Continue groundwater level monitoring on a monthly basis and consider increasing the frequency

during the wet-season; and

Use the Mine Pit water balance and dewatering pumping records to determine the total groundwater

inflow over time.


Impacts to regional hydrogeology are expected to be Negligible. The cone of depression will not impact local

groundwater abstraction during operation. The cone of depression will decrease incrementally post-closure,

as the Mine Pit void fills with groundwater / surface water.

The development of the pit lake is not expected to substantially alter the hydrogeology of the aquifers of the

surrounding area.

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FINAL 9-33

The key expected residual impacts on hydrogeology under normal operating conditions, and their overall

significance for each Project phase, are summarised in Table 9-12. Monitoring will be required over the mine

life to confirm the predictions, and allow management measures to be adapted accordingly.


hydrogeology for each Project phase


Significance



Significance


Construction water use

MINOR

Transfer to site water supply. NEGLIGIBLE

Minor use of groundwater during construction

Operation

Impact to hydrogeology of pit dewatering

NEGLIGIBLE

Expand the Petowal groundwater

monitoring network by converting core

holes into sealed monitoring

piezometers.

Continue groundwater level monitoring

on a monthly basis and consider

increasing the frequency during the wet

season.

NEGLIGIBLE

Pit dewatering drawdown impact area could cause tree mortality in deeper drawdown zones

TMF - Poor groundwater quality

MODERATE

Seepage recovery and recirculation in

TMF

NEGLIGIBLE

Small amount of seepage not recovered from TMF escapes to groundwater


TMF - Poor groundwater quality

MODERATE

Monitoring of seepage groundwater

Seepage treatment if required

NEGLIGIBLE

Seepage may influence low flow

water quality in Badalla Creek

9.6 Surface and Ground Water Quality


Surface water quantity and quality modelling with SWMM (USEPA 2008) has confirmed that creeks and rivers

in the PDA are ephemeral and are therefore susceptible to evaporative concentration effects during cease to

flow events and in the early dry season as pools evaporate. Additionally in the early wet season, the Badalla

Creek is likely to flow into the Gambia River for several weeks before wet season flow is established in the

Gambia River. Predicted surface water quality impacts are shown in Figures 9-8 to 9-10.


Suspended sediment: The primary impact to surface water quality during construction will likely be

suspended sediments generated from land clearing / earthworks, sand / gravel extraction from quarries /

borrow areas, and road construction / unsealed road surfaces. The majority of input will result from water

erosion of disturbed areas during the wet season, while wind erosion will provide some additional input

during drier months, particularly given the Harmattan winds associated with the region (refer to Section 9.13).

The design and construction of access road / road infrastructure will be particularly important in controlling

sediment-laden runoff from the Project site. Roads intercept, concentrate and direct water from potentially

large catchments on compacted surfaces to receiving waters.

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FINAL 9-34

Land clearance and/or topsoil removal associated with site preparation will provide significant areas of

disturbance that will be susceptible to erosion, specifically:

Mine Pit: 36.04 ha;

Access road / road infrastructure: 15.0 ha;

Waste Rock Dump: 80.9 ha;

Tailings Management Facility: 25.5 ha;

Process Plant and ROM Pad: 13.4 ha;

Mine Services Area: 2.7 ha;

Accommodation camps: 8.8 ha; and

Power Station Facility: 8.0 ha.

Hydrocarbons: Diesel fuel for vehicles and equipment will be transported and stored / handled on-site

providing potential for spillage and subsequent impacts to surface and groundwater.

A truck wash will generate <50 m3/day of potentially hydrocarbon contaminated wash water and

<10 m3/week of potentially contaminated sludge in the truck wash sump (refer to Section 9.12).

Non-hazardous waste: Non-hazardous waste will be generated during construction of major Project

facilities (e.g. alkalinity from concrete batching); calcium carbonate, activated carbon, and flocculent will be

stored at the Process Plant, and general refuse generated in workforce accommodation areas, the Mine

Services Area, etc. If improperly stored, non-hazardous waste may pollute surface water during storm events

(refer to Section 9.12).

Nutrients and Pathogens: The workforce required to construct the Project is expected to peak at 886

employees, 396 of which will be accommodated within the Project Footprint. Waste water from the

accommodation / construction facilities will comprise a potential source of nutrients and pathogens that may

be released into receiving waters via grey-water or septic systems. Solid waste landfills may provide an

additional source of pathogens to surface or groundwater if they are not effectively isolated (refer to Section

9.12).

Operation

TMF Supernatant water: Potential pathways of solute discharge related to acidity and/or alkalinity, from the

TMF during operation may include:

Uncontrolled discharge of TMF supernatant water;

Discharge of tailings slurry or return water to the downstream environment from tailings or return

water pipeline failure;

Seepage of tailings pore water through the TMF embankment;

Percolation of tailings pore water through the foundations of the TMF to the down hydraulic gradient

groundwater; and

Failure of the TMF embankment, resulting in a release of tailings and supernatant pond water to the

downstream environment.

Cyanide and reagents: An assessment of potential impacts of tailings disposal in the TMF and potential

impacts to surface and groundwater quality is provided in Section 9.3. In summary, the tailings liquor is

expected to contain elevated concentrations of process reagents (sodium metabisulfite, sodium hydroxide

and copper sulfate), alkalinity, salinity (elevated Na, Ca, Mg, and SO4), nutrients, and dissolved metals. Cyanide

destruction, via the INCO process, will be implemented to maintain WAD cyanide concentrations in the TMF

supernatant pond below 50 mg/L at all times.

As the Project has been designed to eliminate discharge from the TMF during operation, the primary impact

will be to the TMF reservoir surface water. However, percolation of water from the TMF may impact down-

Mako Gold Project


FINAL 9-35

gradient groundwater and downstream surface water from the TMF. Surface water impacts from seepage

may be direct (via seepage directly through the dam wall to the downhill soil surface) or through down

gradient emergence of impacted groundwater.

Uncontrolled or controlled discharge of surface water from the TMF during an extreme storm event, failure of

the TMF dam wall, or surface water overtopping the TMF dam wall would significantly impact receiving

waters pending the concentration of cyanide and nutrients, salinity of the water, and dissolved metals.

Hazardous waste: The following potentially hazardous reagents will be stored at the Process Plant and / or

the Mine Services Area: cyanide, sodium hydroxide, hydrochloric acid, copper sulphate, sodium

metabisulphite, and leach aid (refer to Section 9.12). If discharged beyond containment, each of these

materials pose a potential threat to downstream or down-gradient surface or groundwater, respectively.

Hydrocarbons: Diesel fuel for vehicles and equipment and for the Power Station will be transported to site;

stored at the Mine Services Area and Power Station, respectively; and handled during operation providing

potential for spillage and subsequent impacts to surface and groundwater.

The truck wash at the Mine Services Area will generated truck wash water (<50 m3/week) that may be

contaminated with hydrocarbons.

Nutrients and Pathogens: The workforce accommodation facility will accommodate approximately 130

people during Project operation. As per the Construction Phase, waste water from the accommodation and

administration facilities will comprise a potential source of nutrients and pathogens that may be released into

receiving waters via grey-water or septic systems discharge. Solid waste landfills may provide an additional

source of pathogens to surface or groundwater if they are not effectively isolated. Elevated nitrate

concentrations may be present in the leachate from the waste rock and Mine Pit wallrock, associated with

ammonium nitrate fuel oil (ANFO) blast residues.

Suspended sediment: The PDA is moderately steep and is comprised of soils prone to erosion. During

operation it is expected that erosion and sediment transport will be less extensive then during construction.

However, the unsealed road network, progressive dumping of waste rock and low grade ore, progressive TMF

embankment construction, and soil stockpiles will provide substrate for erosion and potential transport to

receiving waters.


A spillway will be constructed from the TMF during Project decommissioning (refer to Section 9.3) and

discharge of Badalla catchment surface water into Badalla Creek (and subsequently the Gambia River) will

resume. If improperly managed, TMF supernatant water and runoff from the WRD and Mine Pit may pose a

significant potential threat to downstream surface water quality.

Monitoring data from the operation phase in the pit lake, TMF and WRD seepage, and groundwater

monitoring bores, will be analysed to determine any potential water treatment requirements.

As above, deconstruction / decommissioning activities will require vehicle / equipment operation and

workforce accommodation, with associated potential impacts from hydrocarbon spillage and nutrients /

pathogens, respectively.

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FINAL 9-36

Figure 9-8 Surface water quality, potential impacted streams during Construction

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FINAL 9-37

Figure 9-9 Surface water quality, potential impacted streams during Operation

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Figure 9-10 Surface water quality, potential impacted streams Post Closure

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FINAL 9-39


Avoidance

The Project design will reduce potential impacts to surface and groundwater during the Construction Phase

via placement of the majority of the footprint (i.e. Mine Pit, WRD, TMF, Process Plant and ROM Pad, Mine

Services Area) in the Badalla catchment (and diverting surface water to the Badalla catchment for those

facilities that straddle the Badalla and neighbouring catchments). Sediment laden water, hydrocarbons and

other potential contaminants will be managed and mitigated by avoiding significant inputs of potential

pollutants to Badalla Creek and additional tributaries of the Gambia River (refer to below).

Erosion and suspended sediment:

Interception channels will be positioned to capture ‘clean’ runoff and divert it around disturbed areas. Runoff

from the disturbed areas will be routed to sedimentation ponds or the TMF, pending location. Sediment

ponds, ‘clean’ water diversion channels, and contact channels (diversion from Project construction areas) are

designed to capture and accommodate peak flows (100 year 24 hr average rainfall events) modelled for their

respective catchments.

As the timing for earthworks will likely extend into the wet season, sediment control dams, drainage

structures, and additional sediment control facilities will be completed prior to the onset of the 2016 wet

season. An event pond will be constructed below the Process Plant and ROM Pad footprints and a sediment

control pond will be constructed downstream from the TMF.

Each water diversion channel has been designed for continuous flow (i.e. aligned to initiate at a high point

and finish at a low point), terminating at settlement ponds to allow for the settling of entrained sediments

prior to discharge to the environment.

Channels will be designed as follows:

Cut slopes at channel sides at 3H:1V;

Channel depths varying depending on the elevation of the invert;

A 3 m wide access surface will be provided using suitable material to allow maintenance; and

Bed stabilisation and energy dissipation structures will be implemented where channels discharge into

sedimentation ponds / TMF or where channels are steep.

Channels have been designed for the final life of mine footprints and will require maintenance activities to

minimise build-up of material and replacement of bed scour protection.

In addition, the following erosion control and sediment management measures will be implemented during

the Construction Phase to mitigate potential impacts associated with site preparation:

Vegetation clearing will be restricted to the minimum area possible and vegetation will be preserved in

areas where construction will occur and a later date. Areas scheduled for vegetation clearance will be

clearly demarcated and personnel will be informed of the maximum extent of clearance and the

requirement to prohibit heavy equipment from straying beyond demarcated zones;

Where feasible, major earthworks and grading operation will be scheduled for early in the dry season;

Surface water management infrastructure (e.g. cut-off / diversion drains, velocity dissipation devices,

culverts) will be installed in appropriate locations to minimise and control surface water flow over

disturbed areas;

Vegetation on steep slopes and riparian corridors will be preserved where possible; and

Disturbed land areas will be progressively rehabilitated when feasible, with priority rehabilitation and

revegetation undertaken in high risk areas such as steep slopes and sites close to rivers and creeks.

Mako Gold Project


FINAL 9-40

Minimisation

Erosion and suspended sediment:

The following management and mitigation measures (adapted from the Minesite Water Management

Handbook (MCA, 1997) should be implemented to minimise erosion and suspended sediment input to

receiving waters from Access road and road infrastructure facilities:

Roads will be constructed during the dry season to the extent possible. Erosion and sediment control

facilities for unsealed roads will be completed before the onset of the wet season;

The road design will include a drainage system to channel water from the road surfaces to outlets with

erosion and sediment control facilities, including rip-rap at inlets and outlets of culverts and channels

and sediment control basins constructed for larger catchment areas;

Roads will be constructed with cross-fall slopes of (maximum 3%) to promote rapid drainage from

unsealed road surfaces to avoid scouring. Where cross-fall is insufficient, waterbars will be constructed

to direct water to road discharge channels that will be outfitted with velocity dissipaters and sediment

control (e.g. rip-rap, sumps and/or silt fencing);

Drainage from upslope of road surfaces will be diverted via roadside drainage channels to culverts

with velocity dissipaters and sediment control at outlets;

Culverts will be installed at drainage crossings, perpendicular to the road alignment and implemented

with appropriate slopes to facilitate water and sediment movement with deposition and consequent

culvert blockages;

Permanent structures should be designed using an average peak storm recurrence interval of 50 years,

and temporary structures should be designed using an average recurrence interval of two years (24

hour storm events);

Batter slope angles will be minimised to the extent feasible;

Soil will not be side-cast (pushed) over the crest of the low side of the road. Excess soil will be

transported to the topsoil stockpile or temporary stockpiles, with stockpile locations identified prior to

the onset of construction; and

Where feasible, vegetation will be left intact on road verges and roadside batters to reduce surface flow

velocity and erosive potential.

Hydrocarbons

The following management and mitigation measures will be implemented to minimise impacts from

accidental spills associated with transport of hydrocarbons, use of heavy machinery during site preparation,

and storage and handling of hydrocarbons to avoid or minimise potential impacts to surface or groundwater:

All hydrocarbons (e.g. fuels and lubricants) will be stored in fully bunded areas in the Mine Services

Area and / or applicable vehicle laydown / maintenance areas. Bunded areas will be covered to

prohibit rain infiltration. Bunds will have sufficient capacity to contain at least 110% of the tanks’

maximum capacity;

Vehicle maintenance bays, equipment laydown areas, and re-fuelling stations will have perimeter

bunding and interception drains to contain oily runoff. Potentially contaminated surface will be

diverted to the TMF and recovered for use as process water; and

Surface water management features such as diversion bunds, oil/water separators, and interception

drains will be checked on a regular basis to ensure their effectiveness.

The management of the refuelling and maintenance of heavy machinery will include:

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FINAL 9-41

Regular maintenance of vehicles and equipment to prevent hydrocarbon leaks in designated areas

where contaminated runoff can be contained (e.g. Mine Services Area); and

Vehicles and equipment and equipment laydown areas will be sealed for overnight / non-operation

parking.

Management measures associated with potential spills or leaks of liquid hazardous materials will include:

Adequate volume of hydrocarbons spill kits (e.g. Sorbex) will be stored in readily accessible locations

where hydrocarbons are stored or handled;

Personnel will be trained in the emergency preparedness and response protocols (refer to ESMMP).

Emergency Preparedness and Response Plans will be prepared for the Project which will detail training

requirements, storage and handling procedures, clean-up material requirements, etc.

Potential input from the truck wash will be managed accordingly:

The truck wash area will be paved, with surface water directed to a collection sump. Hydrocarbon

contaminated sludge from the sump (<10 m3/week) will be volatilised and then buried in a lined

landfill. Treated wastewater (e.g. from oil / water separator at the sump) will be used for dust

suppression on haul roads.

Nutrients and Pathogens

Temporary Construction Phase workforce accommodation and administrative facilities will be designed to

store and / or treat the volume of wastewater generated from kitchen, bathrooms, toilets, etc. A sewage

treatment plant (STP) will treat water from the workforce accommodation camp, Process Plant, and Mine

Services Area. The method of disposal for treated sludge and / or treated water will be managed accordingly:

STP sludge: surplus activated sludge from all sewage treatment plants (calculated as <50 kg/day) will

be solar dried in a lined pond, and then buried in a lined landfill or co-disposed with plant tailings;

STP treated water from accommodation camps (expected to be 50 – 100 m3/day) will be disposed of

via leach drains; and

STP treated water from the Plant Site and Mine Services Area (expected to be 50 – 100 m3/day) will be

disposed of in the TMF and recovered for use as process water.

The CEMP will provide detailed specifications for greywater treatment and sewage containment, treatment

and disposal that ensure effluent meets discharge guidelines and receiving waters meet ambient water

quality guidelines for nutrients and pathogens.

Mine Pit sump water and TMF seepage water will be monitored for nutrient concentrations during operation

to determine if treatment is required prior to the rehabilitation and resumption of discharge from these

facilities. Water will be treated, if required, prior to its release to receiving waters.

Accommodation and additional facilities that may generate nutrients and pathogens (e.g. toilets, kitchens,

etc.) have been designed to ensure containment of potentially contaminated water.

During operation, the measures listed above for Construction Phase erosion and sediment control;

hydrocarbon management and handling measures; and nutrient / pathogens will be implemented with

additional measure incorporated (refer to below) to accommodate specific Project components. Further

detail is provided in Section 9.11, General Waste and Hazardous Materials.

Cyanide and Process Plant Reagents

The Project will adhere to ICMI Cyanide Management Code (Cyanide Code) Principles and Standards of

Practice for Cyanide Transportation, including independent auditing of procedures and Transportation

Verification Protocols; and Cyanide Code Standards of Practice for handling and storage (refer to Section 9.11).

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FINAL 9-42

The Process Plant will incorporate a cyanide destruction circuit to treat slurry from the CIL circuit using the air

/ SO2 process. Cyanide destruction circuit tailings will be pumped to the TMF at a concentration of less than

50 ppm WAD cyanide (as per the ICMI guideline). Supernatant water will be recovered from the TMF and

returned as process water decant to the Plant for storage in the process water tank and reuse. The TMF is

designed, and will be managed, so that it will not discharge to receiving waters during operation.

The Process Plant design incorporates the following measures to account for potential contaminant

discharge of processing reagents:

Materials handling, containment and bunding in all Plant areas will meet the requirements of the

International Cyanide Management Code as well as legislative requirements;

Plant areas subject to potential contamination from chemical or slurry spills will have concrete slabs

and bund. Bunded areas will be equipped with sumps to recover spilled material and rain from slabs;

and

Spillage exceeding the capacity of bunds will report to and HDPE lined event pond, where it will be

pumped back to the Process Plant for reuse or treatment.

As per Section 9.3, the TMF embankment and the southern portion of the TMF will be constructed with an

HDPE liner to minimise the potential for groundwater seepage. A leakage collection system has been

designed to capture TMF seepage for collection in a lined recovery pond. This water will be pumped back to

the TMF and then the Process Plant for reuse as process water.

All process water that may contain cyanide or process reagents (e.g. copper sulphate) will be monitored

throughout operation and prior to Project decommissioning to ensure that surface water discharge will meet

applicable discharge (GRS, 2002; IFC, 2007) and ambient (USEPA, 2009; EU, 2006) water quality guidelines prior

to the resumption of discharge from the Badalla Valley. Water will be treated, if required, prior to its release to

receiving waters.

Piezometers will be installed down-hydraulic gradient from the TMF to monitor groundwater at the following

locations to determine whether remedial works are required:

Approximately 50 metres downstream of the seepage collection sump; and

Approximately 500 metres downstream of the TMF embankment near the Mine Permit boundary.

Badalla Creek will also be monitored to ensure appropriate management of seepage.

Metals and Salinity

Surface water from the WRD and Mine Pit will be captured in the TMF, with TMF water pumped to the Process

Plant for utilisation as process water. Surface water will not be discharged from the TMF to receiving waters

during operation. Seepage from the TMF and / or TMF pipeline will be captured through a leakage recovery

system, contained in a recovery pond, and pumped back to the TMF.

As per Section 9.2 and 9.3, geochemical analyses of waste rock, tailings / ore, and Mine Pit wallrock found each

have a low potential to generate AMD, NMD or sulfate salinity. Surface water will not be discharged from the

Project Footprint during operation. Regular monitoring of water quality and geochemistry (waste rock,

wallrock, and tailings) will be conducted to confirm the risk remains low and to prepare for post-closure

resumption of discharge from the Project Footprint.

Monitoring of TMF seepage quality and quantity during operation will provide data with respect to the likely

behaviour and characteristics of the seepage expected to be generated by the TMF and WRD during

operation and closure. Natural attenuation processes such as microbial uptake and reactive surface adhesion

will be able to be determined by comparing groundwater quality in monitoring bores downstream of the

facility.

All drainage from the WRD, TMF and Mine Pit will be monitored throughout operation and prior to Project

decommissioning to ensure that surface water discharge will meet applicable discharge (GRS, 2002; IFC, 2007)

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FINAL 9-43

and ambient water quality guidelines (USEPA, 2009; EU, 2006) prior to resumption of discharge to Badalla

Valley. Detailed management strategies relevant to mine material geochemistry are discussed in further

detail in Section 9.3.2. Routine water quality monitoring will also be conducted. If the risk is found to increase

during operation, a geochemistry management plan will be developed to ensure that potential impacts

associated with mine material geochemistry post-closure are minimised.

Hydrocarbons

The Process Plant, Mine Services Area, Power Station and WSD pumping facility are designed to minimise the

potential for hydrocarbon discharge to receiving waters. Facilities’ design incorporates primary and

secondary containment for storage and handling areas.

As per the Construction Phase, Emergency Preparedness and Response Plans will be developed that specify

transport, storage, and handling mechanisms; spill prevention and reaction training; and spill clean-up

material requirements (refer to ESMMP, Volume C).


Salinity and Metals

If discharge occurs from the post mining Mine Pit lake, it may be slightly elevated in salinity and require

treatment such as a designed dilution discharge system or wetland.

There may be an area of groundwater directly under the TMF which will be elevated in some metals and

salinity during the operation and post closure period. During operation this will be managed through

seepage return and groundwater monitoring. The TMF seepage is expected to be relatively low in volume

post closure. The Mine Pit lake and TMF seepage systems will be treated, if required, post closure, to ensure

appropriate ambient water quality is maintained in Badalla Creek.

Erosion and Sediment Transport

As per the Rehabilitation and Conceptual Mine Closure Plan (Volume E), all temporarily disturbed areas will be

rehabilitated and revegetated to create self-sustaining natural ecosystems. Upon successful plant

establishment (i.e. achievement of completion criteria), areas prone to erosion will be minimised. Erosion of

the unsealed road network will provide for an ongoing source of sediment. Roads and associated erosion and

sediment control facilities have been designed to reduce sediment transport to receiving waters.


With monitoring and treatment of surface and groundwater in the PDA, the potential for residual impacts for

the majority of potential contaminants is considered low.

The unsealed road network will provide an ongoing source of suspended sediment from erosion during the

rainy season. The responsibility for post-closure maintenance of these roads will be determined during

stakeholder consultation, should the ownership of these assets be transferred to government of local

communities.

The key expected residual impacts related to surface and groundwater quality under normal operating





surface and groundwater quality for each Project phase

Receptor / Value

Expected Pre-Mitigation

Impact Significance

Key Management & Mitigation Measures Key Expected Residual Impacts and

Overall Impact Significance

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FINAL 9-44

Receptor / Value


Impact Significance




Erosion and Suspended Sediment

MODERATE

Construct site stormwater and sedimentation basin

structures based of hydrological stream order moving

up stream

Develop soil removal mosaic patterns to reduce the

overall area of exposed soil

Use silt fencing and bunding to retain stockpiled soils

MINOR

Some elevation of suspended solids


MODERATE

Vegetation clearing restricted to minimum area possible

and vegetation will be preserved in areas where

construction will occur and a later date.

Where feasible, major earthworks and grading

operations will be scheduled for early in the dry season.

Surface water management infrastructure (e.g. cut-off /

diversion drains, velocity dissipation devices, culverts)

will be installed in appropriate locations to minimise and

control surface water flow over disturbed areas.

Vegetation on steep slopes and riparian corridors will be

preserved where possible.

Disturbed land areas progressively rehabilitated when

feasible, with priority rehabilitation and revegetation

undertaken in high risk areas such as steep slopes and

sites close to rivers and creeks.

Roads constructed during the dry season to the extent

possible. Erosion and sediment control facilities for

unsealed roads completed before the onset of the wet

season.

Road design will include a drainage system to channel

water from the road surfaces to outlets with erosion and

sediment control facilities.

Roads constructed with cross-fall slopes of (maximum

3%) to promote rapid drainage from unsealed road

surfaces to avoid scouring.

Drainage from upslope of road surfaces diverted via

roadside drainage channels to culverts with velocity

dissipaters and sediment control at outlets.

Culverts installed at drainage crossings, perpendicular

to the road alignment and implemented with appropriate

slopes to facilitate water and sediment movement with

deposition and consequent culvert blockages.

Permanent structures designed using an average peak

storm recurrence interval of 50 years, and temporary

structures should be designed using an average

MINOR

Some elevated suspended solids expected during large storm events

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FINAL 9-45

Receptor / Value


Impact Significance



recurrence interval of two years (24 hour storm events).

Batter slope angles minimised to the extent feasible.

Soil will not be side-cast (pushed) over the crest of the

low side of the road. Excess soil transported to the

topsoil stockpile or temporary stockpiles, with stockpile

locations identified prior to the onset of construction.

Where feasible, vegetation left intact on road verges

and roadside batters to reduce surface flow velocity and

erosive potential.

Operation

Hydrocarbons LOW

All hydrocarbons (e.g. fuels and lubricants) will be

stored in fully bunded areas in the Mine Services Area

and / or applicable vehicle laydown / maintenance

areas;

Vehicle maintenance bays, equipment laydown areas,

and re-fuelling stations will have perimeter bunding and

interception drains to contain oily runoff. Potentially

contaminated surface water in the Badalla catchment

diverted to the TMF and recovered for use as process

water; and

Surface water management features such as diversion

bunds, oil/water separators, and interception drains

checked on a regular basis.

Regular maintenance of vehicles and equipment to

prevent hydrocarbon leaks in designated areas where

contaminated runoff can be contained (e.g. Mine

Services Area); and

Vehicles and equipment and equipment laydown areas

sealed for overnight / non-operation parking.

Adequate volume of hydrocarbons spill kits (e.g.

Sorbex) stored in readily accessible locations where

hydrocarbons are stored or handled;

Construction personnel trained in the emergency

preparedness and response protocols (refer to

ESMMP).

The truck wash area paved, with surface water directed

to a collection sump. Hydrocarbon contaminated sludge

from the sump (<10 m3/week) volatilised and then

buried in a lined landfill. Treated wastewater (e.g. from

oil / water separator at the sump) used for dust

suppression on haul roads.

NEGLIGIBLE

Hydrocarbon contaminated soil from spills will need disposal

Nutrients and Pathogens

MODERATE STP sludge: surplus activated sludge from all sewage

treatment plants (calculated as <50 kg/day) solar dried

NEGLIGIBLE

Low level

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FINAL 9-46

Receptor / Value


Impact Significance



in a lined pond, and then buried in a lined landfill or co-

disposed with plant tailings;

STP treated water from accommodation camps

(expected to be 50 – 100 m3/day) disposed of via leach

drains; and

STP treated water from the Plant Site and Mine

Services Area (expected to be 50 – 100 m3/day) will be

disposed of in the TMF and recovered for use as

process water.

groundwater recharge with nutrients

Cyanide and Process Plant Reagents

MODERATE

Materials handling, containment and bunding in all Plant

areas meet the requirements of the International

Cyanide Management Code as well as legislative

requirements;

Plant areas subject to potential contamination from

chemical or slurry spills will have concrete slabs and

bund. Bunded areas equipped with sumps to recover

spilled material and rain from slabs; and

Spillage exceeding the capacity of bunds will report to

and HDPE lined event pond, where it will be pumped

back to the Process Plant for reuse or treatment.

NEGLIGIBLE

Possible transport of CN into TMF seepage requiring treatment



MODERATE

Restoration of landforms and streamlines undertaken

with revegetation and appropriate sediment and erosion

design prior to flow re-establishment.

MINOR


Salinity and metals

MODERATE

Operation Phase monitoring of TMF seepage and pit

dewatering and pit lake water analysed with surface

water quality modelling to determine if further treatment

is required and if so treatment design parameters for

closure treatment system.

MINOR

Possible low flow elevations of water quality in Badalla Creek

9.7 Soils


Site preparation activities (e.g. clearing and grubbing, grading, etc.) and construction of Project components

has the potential to impact soil character (e.g. aeration and moisture holding capacity), topsoil volumes (e.g.

via erosion and sedimentation), and capacity of the landform to promote sustainable plant growth upon

rehabilitation and revegetation during Project decommissioning.

MEC site clearance planning includes excavation, transport, and stockpiling of topsoil and subsoil from

various Project components for utilisation during progressive rehabilitation and for rehabilitation and

revegetation of temporarily disturbed areas during decommissioning and closure (likely the Mine Pit, Process

Plant, WRD, TMF, and WSD).

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FINAL 9-47

In addition, substrate of varying texture (pending Project component) will be required for road construction,

dam construction, TMF liner construction, etc. (e.g. sand, gravel, clay rich substrate). Borrowing for this

material will be conducted within the Project Footprint to the extent possible, but will likely further impact

soil character in the Study Area (within approximately 5km from the PDA) via excavation of current and

additional borrow areas.

The Project Footprint (vegetation clearance area) has been minimised to the extent practicable during Project

design, with the majority of Project components within one small stream catchment (Badalla Valley), limiting

the area of impact. The Project design includes primary and secondary containment areas (concrete bunding,

etc.) in hazardous storage waste storage and handling facilities to protect soil quality in these areas. The

Project will utilise pre-existing (and currently disturbed) quarries to the extent practicable to minimise

potential impacts from borrow activities.

Some potential impacts will have to be managed and mitigated to avoid or minimise impacts during pre-

construction, operation, and decommissioning (refer to below).


Construction activities may impact soils in the PDA in the following respects:

Contaminants: Accidental spillage / leakage of hydrocarbons from vehicles or storage / handling areas

would affect soil and / or water quality. Potential for hazardous materials impacts from the Mine

Services Area, truck wash, etc. are discussed further in Section 9.6 (Surface and Groundwater Quality)

and Section 9.12 (General Waste and Hazardous Materials).

Compaction: The requirement for heavy vehicles / land clearing equipment will compact soil surfaces

during site preparation. For some of the components (e.g. road network, Process Plant and ROM Pad,

Mine Services Area, accommodation camps) the component footprint will require compaction to

support the infrastructure. If unmitigated, compacted soils will inhibit water infiltration, aeration and

the potential for plant establishment following Project closure.

Erosion: Clearing and grubbing vegetation, earthmoving activity, topsoil/subsoil transport, and

topsoil/subsoil stockpiling will promote erosion of soils with wind and water (refer to Section 9.6).

Seed Bank: Excavation and long-term stockpiling of topsoil will likely eliminate the viability of the

seed currently contained therein (pending the respective duration of seed viability for applicable plant

species). The seed bank is however expected to minimise erosion and sediment transport from soil

stockpiles via promotion of plant establishment on long-term stockpiles.

Quarries: Earth-fill borrow material will be required for concrete batching (for facilities construction),

WSD embankment / dam, TMF starter wall construction, and road construction / upgrade activities.

Sand is expected to be hauled to site from a source outside the PDA. Additional borrowing activities

will likely occur on-site, potentially impacting some land at quarry sites for material that cannot be

sourced from the Mine Pit overburden. However, three existing quarries (refer to Figure 9-2) within the

Project Concession Area have been previously disturbed (and not rehabilitated), and are expected to

be utilised for Project borrow requirements, minimising the potential for any additional significant

impacts (refer to below).

General borrow requirements include:

» Sand: It is estimated that approximately 6000 m3 of concrete will be required to construct the

Process Plant, Mine Services Area, Accommodation camp, and various minor facilities. Sand

requirements for concrete are estimated to be 4,950 tonnes. A preliminary review for local sand

availability indicated small quantities of high silt material can be found nearby but are unlikely to

provide the quantities or sand quality needed. As such sand will be sourced from suppliers outside

the PDA.

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FINAL 9-48

» Aggregate and rip-rap: there are a number of basalt outcrops in the PDA that may be suitable for

rock extraction and processing. There are three pre-existing quarry sites within the mining lease.

One in particular has been used recently for the recent N7 highway upgrade. This quarry is ready

for immediate use with a loading ramp and laydown area for stockpiling crushed aggregate already

available.

It is envisaged that a contractor with a portable crushing plant will be employed to produce the

required aggregate (6,500 tonnes). Aggregate will be stockpiled at the quarry site and

progressively transferred to the work site over the following seven months.

» Clay-rich material: Engineering grade material will be required for WSD and TMF embankment /

dam construction and for the TMF HDPE liner. It is anticipated that this material will be sourced

from local borrow areas within 2 km of construction activity.

Operation

As per Section 9.6, soil will be susceptible to erosion and sediment transport during operation, but to a lesser

extent than during construction.

During operation, soil will be susceptible to contamination from potential spills of hydrocarbons or other

hazardous materials which would compromise the soil quality and potentially groundwater / aquifers. The

number of facilities potentially susceptible to inadvertent discharge will increase during operation, including

the Process Plant / ROM pad, WRD, Mine Services Area, vehicle laydown areas, Power Station, etc. However,

less construction activity will minimise potential inputs from vehicle leakage and washing.

Closure / Decommissioning

Rehabilitation and closure activities for those facilities identified as ‘Temporary Impact – Rehabilitated to

Natural Ecosystem’ areas will comprise ripping of soil surfaces to remediate compaction, transport of a

suitable volume of subsoil and topsoil, and placement of subsoil / topsoil on components requiring

revegetation.

Minor wind erosion may occur during soil transport. Significant water erosion and sediment transport may

occur during the first few years following planting / seeding of rehabilitated areas. Subsequent losses of

subsoil are expected to abate following successful establishment of vegetation on exposed surfaces.


Avoidance

The Project has been designed to avoid the physical impacts to the natural landscape by reducing the Project

Footprint to the extent practicable.

Minimisation

Pollutant Contamination

The Project requirements for general waste and hazardous materials that may compromise the integrity of

soils in the PDA if improperly managed are detailed in Section 9.12 (General Waste and Hazardous Materials).

In summary, facilities where wastes will be generated, stored, and handled will have primary and secondary

containment (e.g. bunds and sumps for treatment), hazardous and non-hazardous waste have specific

storage, handling and disposal designations, and vehicles will have hydrocarbon spill kits readily available.

Training for spill prevention and clean-up will be specified in the Emergency and Preparedness Response Plans

(refer to ESMMP, Volume C), which will be developed by contractors / the Company prior to the onset of

construction activities.

Where contaminated soils are detected, the soils will be excavated and contaminates volatilised. Residual

material will be buried in a lined landfill.

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FINAL 9-49

Minimising Area of Disturbance

Vegetation clearing area (Project Footprint) will be minimised to the extent practicable. Areas identified for

vegetation clearing and earthworks will be clearly demarcated prior to activities, and personnel informed of

the limits of clearing. All clearing and vegetation grubbing shall be conducted during the dry season and

erosion / sediment control facilities implemented prior to the onset of the rainy season.

Stockpile Erosion Control Measures

The following measures are recommended to reduce soil loss for topsoil and subsoil stockpiles:

Site stockpiles in suitable locations, including avoidance of natural drainages and steep slopes;

Divert upstream surface water drainage from stockpiles;

Avoid constructing steep stockpile batters;

Seed long-term stockpiles with native grasses to minimise losses from wind and water erosion; and

Implement silt fences or similar sediment control facilities on downhill side of stockpile areas.

Quarries

Suitable engineering earthworks material for WSD and TMF embankment construction from the Mine Pit

overburden or access road / Process Plant footprints will be utilised to the extent practicable. If these

potential sources cannot supply the required volume, or the material is not of suitable texture, borrow area(s)

and import of sand from outside the Project Footprint will be required.

The Project will utilise previously established borrow pits / quarries to the extent feasible to minimise impacts.

There are three pre-existing quarry sites within the mining lease. One has been used recently for the N7

highway upgrade. This quarry is ready for immediate use with a loading ramp and laydown area for

stockpiling crushed aggregate already available. Aggregate will be stockpiled at the quarry site and

progressively transferred to the work site over the following seven months, minimising Project impacts by

utilising a previously disturbed area.

Management and mitigation measures to minimise additional impacts (e.g. erosion and sedimentation, air

quality, noise, vibration) are provided in the respective sections of this chapter.


Topsoil and subsoil handling for rehabilitation

Where topographical and soil conditions are appropriate, the top 0.5 metre of topsoil will be stripped from

various facilities’ footprints (e.g. Mine Pit and WRD) following clearing and grubbing of vegetation. Soil will be

excavated and loaded to dump trucks, for transfer to the long-term stockpile locations and subsequent use in

rehabilitation / revegetation activities.

Topsoil and subsoil will be stockpiled separately, with a register of volumes for each to ensure adequate

material is available of Project construction and rehabilitation activities.

Potential short-term stockpile locations should be identified as soon as possible, with some of the following

considerations:

Minimise transport distances;

Utilise planned road network; and

Utilisation of a moderately flat area, with no natural surface water drainages.

A survey for potential topsoil and subsoil stockpile areas is required to ensure capacity is in line with volume

requirements.

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FINAL 9-50

The soil character of temporarily impacted areas will be rehabilitated to provide a medium for successful and

sustainable establishment of native vegetation. Greater detail regarding decommissioning / closure

strategies for temporarily impacted areas are provided in the Rehabilitation and Conceptual Mine Closure Plan (Volume E).

In summary, temporarily impacted areas will be rehabilitated via the following procedure:

Where applicable, the facility will be dismantled (and remediated if contaminated), and materials

transported to designated disposal facilities or provided to local communities / government as

needed;

The landform will be graded to match contours of adjacent landforms (with respect to drainage);

Surface soils will be ripped to approximately 1 metre depth to reduce compaction;

Where topsoil was removed during construction, topsoil will be placed and graded to contour to

approximately 0.3m depth (~1.5m depth for TMF) during the dry season;

Native vegetation of local provenance will be planted / seeded early in the rainy season to promote

stability of the landform (in addition to providing viable habitat); and

Planted / seeded areas will be monitored for relative success of plant establishment. Where plant

establishment does not meet Project Success Criteria (refer to Rehabilitation and Conceptual Mine Closure Plan), re-planting or seeding of areas will be conducted until Success Criteria are achieved.


Site preparation activities (i.e. clearing of vegetation, earthworks, etc.) will provide substrate for erosion and

sedimentation. Management measures provided in Section 9.6 are expected to minimise erosion and

sedimentation, however some residual impacts during construction are anticipated.

The impacts of erosion and sediment transport will be largely mitigated during operation with the utilisation

of the TMF and event ponds / sediment basins to prevent discharge from Badalla Valley. Erosion of the

unsealed road network will be minimised, though not completely avoided, during operation. A low level of

downstream sedimentation / loss of soil from the PDA is anticipated.

The unsealed road network will remain an active source of low-level soil loss (erosion and sedimentation),

post-closure.

Compacted areas are expected to be mitigated upon closure, with Negligible residual impacts.

The key expected residual impacts related to soil management under normal operating conditions, and their



accordingly.

Table 9-14 Summary of key expected pre-mitigation impacts, mitigation measures and residual impacts on soils

for each Project phase

Receptor / Value


Significance



Erosion and loss of soil resource

MODERATE

Construct site stormwater and sedimentation

structures based of hydrological stream order moving

up stream

Develop soil removal mosaic patterns to reduce the

overall area of exposed soil

MINOR


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FINAL 9-51

Receptor / Value


Significance


Use silt fencing and bunding to retain stockpiled soils

Operation


MODERATE

Site stockpiles in suitable locations, including

avoidance of natural drainages and steep slopes

Divert upstream surface water drainage from

stockpiles

Avoid constructing steep stockpile batters

Seed long-term stockpiles with native grasses to

minimise losses from wind and water erosion

Implement silt fences or similar sediment control

facilities on downhill side of stockpile areas

MINOR




MODERATE

Where applicable, the facility will be dismantled (and

remediated if contaminated), and materials

transported to designated disposal facilities or

provided to local communities / government as

needed

The landform graded to match contours of adjacent

landforms (with respect to drainage);

Surface soils ripped to approximately 1 metre depth to

reduce compaction

Where topsoil was removed during construction,

topsoil replaced and graded to contour to

approximately 0.3m depth (~1.5m depth for TMF)

during the dry season

Native vegetation of local provenance planted /

seeded early in the rainy season to promote stability

of the landform

Planted / seeded areas monitored for relative success

of plant establishment

MINOR


9.8 Air Quality


Air dispersion modelling was conducted to evaluate the extent of potential Project emissions from the mine

site. Full details of the modelling conducted are provided in the Air Quality, Noise and Vibration Baseline and Project Modelling report (Volume A, Appendix 4).

Due to the local topography surrounding the Mako Gold Project footprint, the CALPUFF model (Version 7.12)

was employed to simulate dispersion as it incorporates calculations to handle multi-level meteorology and

three-dimensional terrain features, and has been adopted by the U.S. Environmental Protection Agency (US

EPA) in its Guideline on Air Quality Models as the preferred model for assessing long range transport of

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FINAL 9-52

pollutants. NASA Space Shuttle Topography Model (SSTM3) radar data was included in the CALPUFF model

for terrain impacts, incorporating surface meteorology data recorded by MEC from the site meteorological

station, while prognostic 2012 meteorological data for the region was produced using the CSIRO TAPM v3

model (‘The Air Pollution Model’, CSIRO 2005). Key modelling outputs are presented in Figure 9-11.

Air quality simulations were compared against the standards for ambient air quality set out in the IFC/World

Bank Group’s Environmental, Health and Safety Guidelines (2007), which are based on the World Health

Organization (WHO) Air Quality Guidelines (2005). The WHO Guidelines consider the potential health impacts

associated with varying concentrations of airborne pollutants. Senegal has also issued a standard for

emissions to air and air quality Norme Sénégalaise NS 05-062 (“Pollution atmosphérique – Norme de rejets”).

Air pollutants such as fugitive dust emissions, measured as particulate matter of varying particle size (e.g.

PM10 and PM2.5); and emissions including carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen

(NOx), sulfur dioxide (SO2), ozone (O3) and volatile organic compounds (VOCs) will be emitted during the

Construction and / or Operation Phases. A significant portion of the potential air quality impacts are

minimised via Project design. Project design elements for the Process Plant, Power Station, Mine Pit and WRD

(refer to Operation, Section 9.8.2) will reduce impacts to sensitive receptors to less than significant.

The primary potential air quality impacts likely to arise from the Mako Gold Project, if unmitigated, may

include:

Dust emissions from vehicular and equipment transport on unsealed roads and exposed soils,

particularly given the extensive dry season and Harmattan winds;

Exhaust emissions from fuel combustion in heavy vehicles and plant machinery, including the

generation of CO, SO2, NOx, particulate matter (PM10 and PM2.5) and VOCs; and

Combustion emissions from the Power Station for power generation during Project operation. The use

of diesel will produce emissions of CO, SO2, NOx and particulate matter (PM10 and PM2.5).


During the Pre-Construction / Construction Phase, there will be a number of Project-related emission sources

that may impact local air quality as summarised in Table 9-15

Table 9-15 Project-related air emission sources during the Construction Phase

Emissions source / Project activity Type Emissions intensity Duration / frequency

Fugitive dust emissions from road infrastructure associated with

construction vehicle and material movement on unpaved access

and haul roads within the Project Development Area

Fugitive Major Short-term / daily

Fugitive dust emissions from mechanical disturbance of soil

material associated with earthworks, site preparation, and land

clearing by graders and bulldozers

Fugitive Major Short-term / daily

Wind erosion from freshly exposed areas (e.g. unconsolidated

material stockpiles, topsoil removal, etc.) generating fugitive dust

Fugitive Moderate Short-term / daily

Combustion emissions1 from diesel powered vehicles and plant

machinery, including: particulate matter (PM10 and PM2.5), CO,

NOx, SO2, and VOCs

Fugitive Minor Short-term / daily

Smoke emissions from burning Project wastes comprised of

particulate matter (PM10 & PM2.5) and other air pollutants

Fugitive Moderate Short-term / once-off

Particulate emissions from concrete batching Point

source

Minor Short-term / continuous

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1. The rates of vehicle and plant emissions and potential impact to surrounds would depend on the number, type and condition of

combustion engines used, fuel quality, and intensity of use.

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Figure 9-11 Comparison of predicted dispersion of unmitigated PM10 particulate concentrations from all Project

components for construction (top) and operation (bottom). Red contour represents WHO 24-hour criterion (50

micrograms/m3)

Land clearance and earthworks to allow construction of primary Project components will expose moderately

large surface areas to wind erosion / dust generation. Vegetation clearing; topsoil stripping, loading and

transport; earthworks; and topsoil stockpiles will generate dust in the Badalla catchment during the dry

season.

Significant dust emissions during Construction (from the perspective of social receptors) are expected to

result from utilisation of the current road network during the Construction Phase, construction of the Main

Access Road near its intersection with National Route 7, and upgrades to the existing road network.

Unmitigated fugitive dust emission from travel on the unsealed road network and construction / upgrades to

road infrastructure would likely be significant.

The magnitude of air quality impacts for the remainder of parameters listed from combustion of diesel fuel in

vehicles is expected to be relatively low during construction.

Construction Phase impacts to local air quality will be short term, localised and staged over a moderately

short period of time (approximately 20 months). Localised air quality impacts are expected to occur within

approximately 1 km of the construction areas and 200 m of unsealed roads (depending on weather

conditions).

Impacts from Quarry Use

During the Construction Phase, the Project will utilise an existing quarry which is located close to the N7 Road

and the Mine Access Road (the most northern quarry indicated on Figure 4-1). No blasting will be conducted

at the quarry. It is envisaged that a contractor with a portable crushing plant will be employed to produce the

required aggregate (6,500 t) during a day shift only operation over three to six months to produce the

required aggregate. It is expected that the production of aggregate will be a one-off activity which produces

the full Project requirements. Aggregate will be stockpiled at the quarry site and progressively transferred to

the work site.

During active use of this quarry, there is the potential for the extraction of rock and use of the portable

crushing plant to result in dust emissions, though gaseous combustion emissions (SO2, NOx and CO) are

expected to be minimal, associated with generators and vehicle emissions. Potential impacts associated with

dust emissions from quarries will be temporary, and restricted to a three to six month period during the

Construction Phase of the Project. The closest sensitive receptors to the quarry site are:

Road users of the RN7 (closest point of road located 300m from quarry)

Road users of Mine Access Road (closest point of road located 250 from quarry)

Negue Bako and Niemenike are the closest villages to the quarry (closest residences located approximately

2.5 km east of quarry boundary).

Modelling of potential dust emissions from the portable crushing plant used at the quarries was conducted

using the CALPUFF dispersion model to simulate particulates from the quarry. The model predictions

indicated that dust from the quarry will not significantly impact road users on the RN7, Mine Access Road nor

local villages, with predicted maximum concentrations from the single crusher at these receptors being

significantly below national and international particulate criteria. Dust impacts from the quarry are mostly

expected to occur within 200 m of source due to dust fallout, but could extended further in exceptional

conditions such as very high winds, temperature inversions, or very calm conditions where dust build-up can

occur.

Operation

Based on conservative modelling for dust emissions generated by Project activities, international (WHO Air

Quality Guidelines 2005) criteria for air quality may be exceeded in the PDA close to the sources, but are not

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FINAL 9-55

predicted to exceed international criteria at sensitive receptors (Figure 9-11). A more detailed air emissions

inventory is provided the Air Quality, Noise and Vibration Baseline and Project Modelling (Volume A,

Appendix 4).

Mining and processing activities will contribute particulate matter, PM10 and PM2.5 (i.e. the Process Plant,

Petowal Pit, TMF, WRD, ROM Pad stockpiles, and Project Access Roads). In addition, the Power Station will be a

source of stationary combustion emissions during the Operation Phase. Project emission sources are

summarised in Table 9-16 according to emission type, intensity and duration and frequency of emission.

Table 9-16 Project-related air emission sources during Project Operation

Emissions Source / Project Activity Type Emissions

Intensity

Duration /

Frequency

Fugitive dust emission sources from mining and processing activities

including:

Drilling and blasting within the Mine Pit;

Excavating and earthmoving;

Ore processing (crushing and screening), handling (loading,

unloading), conveying, and stockpiling;

Transporting and dumping ore and waste to the processing plant

and WRD on unsealed surfaces; and

Wind erosion from exposed areas (e.g. WRD, soil stockpiles,

ROM stockpiles, and potentially exposed dry tailings in the TMF)

Fugitive Major Ongoing / daily

Stack emissions of CO, SO2, NOx, particulate matter (PM10 and PM2.5) at

the Power Station from diesel combustion.

Point Moderate Continuous

stationary

source

Combustion emissions of CO, SO2, NOx, particulate matter (PM10 and

PM2.5) from mining and processing activities. Such activities include:

Blasting

Drilling with diesel-operated top hammer rigs

Excavating ore by shovels and excavators

Earthmoving ore and wastes using graders and bulldozers

Trucking ore and waste to the processing plant and WRD on

unsealed surfaces

Fugitive Moderate Ongoing / daily

Road fugitive dust emissions from vehicular traffic on unpaved roads,

particularly during dry season.

Fugitive Moderate Ongoing / daily

Combustion emissions of CO, SO2, NOx, particulate matter (PM10 and

PM2.5) from vehicular traffic.

Fugitive Minor Ongoing / daily

Typically, significant impacts would remain close to the ground, particularly in low wind conditions. However,

there will be certain meteorological conditions (i.e. high winds, dry conditions, calm conditions, temperature

inversions) that may lead to dust plumes of particulate matter exceeding applicable WHO and national

standard criteria for PM10 and PM2.5 without proper mitigation. In addition, larger particulates, which do not

pose a health impact, may deposit within a short distance of these sources and may potentially affect

vegetation health.

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FINAL 9-56

Major air emission sources identified for each Project component are further discussed in more detail in the

following sub-sections.

Process Plant and ROM Pad

If unmitigated, significant fugitive dust emissions are anticipated from the following sources:

Ore crushing, screening and conveying (on potentially uncovered conveyors) within the three stage

crushing circuit of the Process Plant;

Loading quick lime into the silo storage facility;

Dumping and handling of ore at the ROM Pad and ROM bin; and

Stockpiling ore at the ROM Pad.

Mine Pit

If unmitigated, major fugitive dust sources from the Mine Pit are expected to include:

Excavators loading mined ore into dump trucks; and

Pit blasting to help remove overburden and access targeted ore.

Dust generated from the mining operation will be low in metals due to the geology of the deposit. Silica and

some fibrous minerals such as actinolite are present within the waste and ore material and may be present in

dust at levels that could potentially affect the health of workers if exposure is high.

Waste Rock Dump and TMF

The unloading of waste rock at the WRD and TMF disposal will provide a source for wind erosion from the

facilities which may result in fugitive dust emissions during dry and windy conditions, if unmitigated.

Diesel Power Station

Power during the Operation Phase will be supplied by a 16.2 MW Power Station, comprising of nine 1.8 MW

diesel generators Combustion emissions from this source will include CO, SO2, nitrogen dioxide (NO2), and

particulates (PM10 and PM2.5).

The use of diesel reduces emissions from the Power Station relative to an heavy fuel oil-powered facility by

approximately 30%, and the CALPUFF dispersion models predict that that positioning of the power station at

Badalla Valley also decreases ground-level concentrations of particulates (note that model is sensitive to

emission parameters). The CALPUFF dispersion models predict that assumed emissions of all target species

will not exceed international (WHO) or Senegalese ambient air criteria. However, short individual stacks,

typical of small generators, may produce enhanced ground-level concentrations of emitted pollutants close

to the sources due to reduced dispersion, ground-turbulence and building-wakes (within 200 m). Particulate

matter PM10 concentrations are predicted to fall sharply with distance (due to particulate drop-out) and

ground-level concentrations at receptor villages are predicted to be below 0.5 micrograms/m3.

High concentrations of baseline PM10 have been recorded in the Petowal region, thus cumulative

concentrations may exceed international particulate guidelines when any additional mine-related, processing

and transportation sources are considered.

Project Access Roads and Haul Roads

During Project operation, the use of unpaved road network for trucking mined ore from the Mine Pit to the

ROM Pad and waste rock from the pit to the WRD will create a fugitive dust source if not appropriately

mitigated.

Localised air quality impacts including an increase in ambient levels of fugitive dust and combustion exhaust

emissions will occur within 200 m of the haul roads.

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Air quality emissions associated with the use of the Main Access Road will include both exhaust

emissions and dust. This dispersal of dust emissions to areas surrounding the roads and their levels at

sensitive receptors will be dependent on factors such as the distance of the receptors from the road,

topography and prevailing wind conditions. Exhaust emissions are not expected to be significant.

Quarries

No air quality impacts from Project quarries are expected to occur in the Operations or Decommissioning /

Closure Phases, as no use of quarries will be required during these phases.


Impacts on air quality during the Decommissioning / Closure phase are expected to be similar to those in the

Construction Phase. Dust and gaseous emissions during decommissioning/closure will primarily be

associated with the removal of site components by trucks, and rehabilitation of site. The ceasing of activities

such as blasting, mining of the pit, processing and Power Station will significantly reduce emissions to air,

relative to operation. Furthermore vegetative cover of open areas is anticipated to be advanced, providing

additional attenuation of fugitive dust to nearby receptors. Some additional temporary dust and vehicle

exhaust emissions associated with truck removal of major plant components and site clearance is anticipated

along the unsealed roads used by the Project.


Avoidance

A significant portion of the potential air quality impacts of the Project have been avoided via the Project

design. As summarised in Table 9-17 a number of specific components of the Project have been designed to

minimise air pollutant emissions.

Table 9-17 Project design measures adopted for managing air quality impacts

Project

Component

Specific Air Quality Abatement Measures Adopted

Power Station Selection of Power Station generators compliant with IFC Ambient Air Guidelines (2007)

Consideration of best industry practice emissions reduction technologies to reduce emissions from diesel

usage, such as:

» Use of low-sulfur/low-emission diesel fuel where available and compatible with generators

» Primary dry methods - low NOx combustion process including: late fuel injection start, high

compression ratio, optimised combustion chamber, optimised fuel injection rate, and suppressed

peak temperatures;

» Secondary methods for flue gas emissions reduction techniques, such as particulate traps, wet or

dry scrubber, electrostatic precipitator (ESP), cyclone or fabric filter (bag house).

» Selective catalytic reduction (SCR) process, which can be added to reduce NOx emissions by 80-

90% using an aqueous reagent of urea or ammonia (catalysts may not be compatible with high-

sulfur-content diesel fuel)

Process Plant

and ROM

Pad

Water sprays, dust collection and wet scrubbing systems to be installed in the crusher, screening circuit

and lime addition to minimise dust emissions from the process plant

Fugitive emissions within the processing area will be contained to the extent practicable by either:

» Enclosing or covering fugitive source emissions such as conveyors, hoppers, bins)

» Increasing and maintaining moisture content in ore-handling areas via water carts to minimise

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Project

Component

Specific Air Quality Abatement Measures Adopted

windblown and traffic generated dust

» Employing air extraction and treatment through a baghouse or cyclone for material handling sources

Project

Access

Roads and

Loading

Areas

Consider sealing the Main Access Road with gravel

Consider using eco suppressants to reduce water use and frequency of application

Mine Pit Apply best practice blasting techniques to minimise dust and gaseous emissions

Waste Rock

Dump Progressively revegetate unused areas of waste rock

Minimisation

The following section outlines the proposed management measures to address air quality and dust impacts

and are generally consistent with those prescribed in the World Bank(WB)/IFC General EHS Guidelines 2007.

The Company will undertake the following management and mitigation measures to minimise potential air

quality impacts associated with earthworks, vehicular movement and exhaust emissions:

Vegetation and topsoil removal will be minimised to the extent practicable for Project construction;

Disturbed areas will be cleared and rehabilitated / revegetated as soon as practicable, thereby limiting

exposure of disturbed surface areas;

Primary dust generating activities will be avoided / mitigated during high winds (e.g. loading, hauling

and dumping of topsoil);

Open burning of waste and vegetation will be restricted or prohibited. It is anticipated that

authorisation will be required prior to burning, if conducted, to limit smoke generation;

Dust containment and suppression controls will be applied where necessary, i.e. during the dry season

and frequency of dust suppression / watering will increase during periods of high risk (e.g. dry and

windy conditions);

Air quality emissions for particulate matter will be monitored at existing dust monitoring stations in

the PDA and near sensitive receptors to evaluate the performance and adequacy of management and

mitigation measures;

Minimising worker exposure to dust through personal protection measures and monitoring the

exposure of workers to dust derived from waste and ore material; and

Village consultations will be undertaken regularly to qualitatively assess the impacts of dust

generation on sensitive receptors. This information will be utilised to improve dust suppression

techniques / frequency.

Additional controls for addressing specific air emission sources are summarised in Table 9-18.

Table 9-18 Air quality mitigation and management controls during Construction

Emissions

Source

Mitigation and Management Controls

Unsealed Mine

Access Road Apply gravel to the Mine Access Road surface if practicable.

Apply water or eco dust suppressants to all unsealed roads and trafficked areas, particularly near

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Emissions

Source


Construction sensitive receptors.

Cover all loose loads on trucks to and from worksites. Securely fix tailgates of road transport trucks

prior to loading and immediately after unloading.

Regularly maintain the Mine Access Road

Implement a speed limit of 50km/hr

Unsealed Project

Access Roads and

Loading Areas

Apply suppressants / water to access roads and loading areas used during the dry season near

sensitive receptors.

Limit driving speed on unsealed access roads, particularly through villages, residences or

environmentally sensitive areas. Enforce a speed limit of 20 km/h through settlement areas.

Seal / apply gravel to all roads where feasible.

Regularly maintain unsealed access roads.

Stockpiles Minimise length of time that topsoil is stockpiled, where practicable.

Plant / revegetate long-term topsoil stockpiles (not used for more than three months).

Rib and roughen smooth surfaces to reduce wind velocity.

Locate stockpiles in areas naturally sheltered from wind, if feasible.

Restrict height of soil stockpiles to the extent practicable (given potential land area restrictions).

Vehicle exhaust

emissions Regularly maintain vehicles.

Prevent overloading of trucks.

Prohibit vehicles from queuing or idling and turn off engines when the vehicle is parked near

sensitive receptors.

Schedule vehicle deliveries to prevent congestion

Use low emission fuels (i.e. containing less than 0.5% sulfur) where available

Consider using low emission diesel engines and/or catalytic convertors for on-site vehicles, trucks,

excavators, etc.

Additional management and mitigation will be required during the Operation Phase to avoid or minimise

adverse impacts to air quality (refer to Table 9-19). Measures listed above for potential impacts during the

Construction Phase will also be employed (where appropriate) during Project operation.

Table 9-19 Additional air quality controls during Project Operation

Emissions

Source


Mining and

processing Disturb only the minimum area necessary for mining.

Locate transfer stations (dumping / loading) in areas sheltered from wind, where possible

Consider water spray systems via computer to site meteorological station, and only activate above

certain temperatures, wind speeds and wind directions to conserve water use, and control dust

suppression.

Drilling and Lower dust aprons during drilling.

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Emissions

Source


blasting

Equip drills with dust extraction cyclones or water injection systems.

Use water injection or dust suppression sprays prior to undertaking drilling or blasting when high

levels of dust are being generated.

Stockpiling Maintain water sprays or eco dust suppressants on stockpiles to reduce the risk of airborne dust.

Locate stockpiles in areas sheltered from wind.

Rib and roughen surfaces to increase surface wind friction

Revegetate or cover any unused or exposed areas with wood chippings or grass matting.

Regular maintenance of vehicles and machinery and use of low sulfur diesel and appropriate technologies

(e.g. low emission engines) and filters will help to reduce NOx and SOx emissions and therefore reduce local

air pollution. Excessively dry and dusty roads will be sprayed with water or, more preferably, eco suppressants

to conserve water use, in order to control airborne dust. Vehicle speeds will also be controlled on all access

roads.

Monitoring

Regular air quality monitoring will continue throughout the Project life to confirm the effectiveness of

mitigation measures. To ensure the level of air quality impact remains within acceptable standard levels, an

air quality monitoring plan should be developed for the Project, including:

Continuous monitoring of ambient air concentrations for PM10 and PM2.5, CO, NO2, NOx, and SO2 at

selected locations near the Petowal Mine Pit and villages;

Periodic (monthly) monitoring of dust deposition rates at selected locations near the Petowal Mine Pit

and villages; and

Meteorological monitoring, including temperature, humidity, rainfall, wind speeds and directions.


Management and mitigation measures to minimise potential impacts during the Construction Phase will be

employed where appropriate during the Decommissioning / Closure phase.

Progressive rehabilitation and revegetation activities will reduce the area of exposed soil with potential to

generate dust emissions over the Project life. Detailed strategies are provided in Volume E, Rehabilitation and Conceptual Mine Closure Plan.


During Construction, Negligible air quality impacts from Project works within the PDA for villages and other

sensitive receptors in the surrounding area are expected.

The use of the current unpaved village road network during the Construction Phase will generate significant

particulates if dust suppressant methods are not adopted during the dry season. Localised air quality impacts

are expected to occur within 200 m of unsealed roads (depending on weather conditions). During the dry

season, the villages of Mako and Linguekoto could experience Minor impacts from dust during the upgrade

of Mako-Tambanoumouya road, as their settlement areas are located directly along this road. These impacts

will be short term, localised and vary over time depending on the Project activities undertaken and the

success of the dust suppression measures employed, and will cease once the Main Access Road is completed.

With diligent application of prescribed management measures, dust impacts for other sensitive receptors in

the vicinity of the Project are expected to remain below relevant criteria during the Construction Phase.

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In the Operation Phase, there is the potential for Minor dust impacts on sensitive receptors to occur within

approximately 5 km of the PDA during the dry season. These impacts will primarily relate to fugitive dust

emissions from drilling and blasting within the Mine Pit, as well as excavating, earthmoving and processing

(crushers) etc. Combustion emissions from diesel vehicle exhausts, machinery and generators as well as the

operation of the Diesel Power Station may also contribute to Minor impacts.

No significant dust impacts on sensitive receptors are expected from the Main Access Road during the

Operation Phase as no such receptors occur within 200 m of the road. However, receptors and the level of

total impacts will depend greatly on wind direction and other weather conditions. The main recorded local

wind directions are from the East (E) during the dry season (Nov - May), which will reduce impacts on sensitive

receptors as the nearest villages are located to the South and South-East of the Project Footprint. However,

valley regions such as the Gambia and Wayako Valley, are also known to be prone to down-slope flow of cool

air, which can form "valley-winds" which may influence the dispersion of Project emissions, particularly at

night-time.

Negligible air quality impacts are expected to occur for sensitive receptors in the Decommissioning / Closure

Phase. If potential impacts are effectively mitigated, Project related emission sources will be minimised.

The results of air quality monitoring and ongoing village consultations should inform the Project of the

efficacy of dust suppression employed over the Project life. Careful consideration of the rate, timing and

frequency of dust suppression near receptors will be essential for avoiding Moderate or Major residual

impacts for local villages.

With diligent application of prescribed management measures, potential air quality impacts from the

remainder of Project-related emission sources are considered Minor and are expected to remain below

relevant criteria, including World Health Organization (WHO) Air Quality Guidelines 2005 and Norme

Sénégalaise NS 05-062, “Pollution atmosphérique – Norme de rejets.

The key expected residual impacts related to air quality under normal operating conditions, and their overall


life to confirm the residual impact predictions, and allow management measures to be adapted accordingly.

Table 9-20 Summary of key expected pre-mitigation impacts, mitigation measures and residual impacts on air

quality for each Project phase


Significance




Air Quality (for Mako and Linguekoto Villages)

MODERATE

The PDA will be enforced, ensuring public access is prohibited

Minimising the size of the Project Footprint

Vegetation and topsoil removal will be minimised to the extent practicable

Disturbed areas will be cleared and rehabilitated / revegetated as soon as practicable

Primary dust generating activities will be avoided/mitigated during high winds

Dust suppression will be used on access roads used during the dry season near sensitive receptors

Enforce a speed limit of 20 km/h

MINOR

Construction and upgrades of the Project Access Roads and utilisation of the current road infrastructure

Fugitive dust emissions from road infrastructure associated with construction vehicle and material movement on unpaved access roads.

Air Quality (for other sensitive receptors in vicinity of Project)

MINOR

NEGLIGIBLE

With diligent application of prescribed management measures, potential air quality impacts are expected to remain below relevant criteria

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Significance




through settlement areas

Air quality monitoring.

Operation

Air Quality (for receptors within 5 km)

MODERATE


MINOR

Fugitive dust emissions from drilling and blasting within the Mine Pit, as well as excavating, earthmoving and processing (crushers) etc.

Dust emissions from vehicular traffic on access roads

Combustion emissions from diesel vehicle exhausts, machinery and generators

Combustion emissions due to the operation of the Diesel Power Station

Volatile emissions from fuel storage

Air Quality (for receptors >5 km)

NEGLIGIBLE

NEGLIGIBLE



Air Quality MINOR




NEGLIGIBLE


9.9 Noise


This section considers the potential noise impacts of the Project on the existing acoustic environment.

Details of proposed mitigation and management measures to minimise noise impacts are provided, with

further detail and monitoring strategies presented in the Air Quality, Noise and Vibration Baseline and Project Modelling report (Volume A, Appendix 4).

As the surrounding environment is largely undeveloped (albeit with surrounding villages and agricultural

activities), background noise levels are relatively low, though night-time ambient noise can be relatively high

due to natural insect and wildlife noise. The development of the Mako Gold Project will introduce new

sources of noise and will elevate noise emissions in the PDA and transport routes during the Construction,

Operation and Decommissioning / Closure Phases.

The primary sources of noise from the Mako Gold Project will include:

Transit of vehicles used for construction, transport and mining activities;

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Construction activities, including pile drivers, excavators, dozers, etc. used for earthworks, levelling and

site preparation;

Blasting in the Mine Pit, quarries, and road construction areas;

Ore crushing and ongoing Process Plant operation; and

Power Station.

The significance of noise impacts to the local acoustic environment will depend on a range of factors

including topography, timing of activities conducted, duration of noise emissions, and weather conditions.

Potential noise impacts that may occur during each phase of the Mako Gold Project are assessed for

construction, operation and decommissioning / closure.

The assessment of noise impacts to the surrounding sensitive region was simulated using the Canadian dB

Foresight screening level model (Version 2.05, 2015). The dB Foresight model complies with the International

Standard ISO 9613-2, and considers the following parameters for the noise prediction analysis:

GPS location of each sound source in latitude and longitude;

Ground type (porous, mixed or hard);

Source elevations, height and directivity;

Source mid-band frequencies in Hz;

Physical size of the sources;

Receptor GPS locations, height and elevation;

Terrain;

Attenuation due to natural and man-made barriers;

Air temperature and relative humidity; and

Atmospheric absorption.

Noise attenuation in air is dependent on noise pitch, with low-frequency noise sources (such as blasting and

crushers), propagating farther. Noise propagation is also dependant on the temperature and humidity of the

air, with high temperatures and humidity allowing farther noise propagation. The atmospheric attenuation of

noise sources in dB/km was calculated in standard frequency bands as per ISO 266.

Maps of pre-mitigation modelled noise levels for the PDA and surrounds are presented in Figure 9-12 to

Figure 9-16.


The predominant noise sources during construction will include vehicles / earthmoving equipment, pile

drivers, tippers and backhoe, concrete trucks, and hydraulic excavators. Such emissions are likely to be

associated with the following construction activities:

Clearing, spoil removal, ground surface levelling and site preparation;

Excavation and earthworks;

Drilling and foundation installation;

Erection and commissioning of plant and infrastructure; and

On-site and off-site construction traffic.

Noise impacts from early site preparation and construction activities can vary widely depending on the type

of equipment used and noise produced while existing topography and vegetation provide natural shielding

that may decrease the noise impact from the Project.

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Construction Phase noise emissions from the PDA will be temporary (approximately 20 months), localised in

nature, and short-term. Based on the predicted noise levels, in the absence of mitigation Minor night-time

noise impacts from construction activities would be expected to occur for sensitive receptors such as villages

within approximately 5 km from the construction areas within the PDA. It should be noted that the ambient

night-time noise levels recorded in baseline noise surveys in the area are already generally close to that of the

conservative IFC night-time noise criterion 45dB(A), though construction noise may differ from the existing

noise regime.

Noise will occur as a result of construction and upgrades of the Project Access Roads and utilisation of the

current road infrastructure in the Project region. Use of the current road between Mako and Linguekoto for

access to the WSD will be short-term, as the majority of Project personnel will be housed within the PDA and

will utilise the Main Access Road upon its completion which does not pass directly through existing village

settlement areas.

Vehicular traffic on the haul route (National Route 7) will be a source of noise emission, but is not expected to

significantly change ambient conditions as background traffic on the RN7 is typically composed of heavy

vehicles (53%).

Operation

The primary noise impacts of the Project are expected to occur during operation, where blasting, mining and

processing activities as well as truck haulage will likely affect the local ambient acoustic environment. Project

activities with the potential to cause these adverse impacts on the acoustic environment during the

Operation Phase are described below.

Mining and Processing Operations

The principal noise sources for the mining, processing and materials handling activities will be from blasting,

drilling, (further discussed below), loading, hauling and crushing using heavy equipment, including

excavators, dozers, conveyors, haul trucks and diesel-operated top hammer rigs for waste and ore.

Noise emissions from the Mine Pit will vary depending on the amount of shielding provided by the pit walls.

Blasting

Blasting for ore extraction is expected to generate the most significant noise impacts that may exceed noise

standard criteria beyond the immediate mining area. The impact of periodic blasting to the surrounding

acoustic environment is expected to be significant but short-term.

As above, noise emissions from the Mine Pit will vary depending on the amount of shielding provided by the

pit walls. The modelling indicated that the blasting noise emissions were significantly lessened for sensitive

receptors when the existence of the pit was included in the models.

Based on the analyses conducted, blasting from the Petowal deposit may be perceptible at the following

sensitive receptors at the start of the Operation Phase (in the absence of noise attenuation from the pit):

Tambanoumouya (3.0 km from the Mine Pit);

Proposed Operation Accommodation Camp (3.0 km from the Mine Pit).

Kerekonko (4.0 km from the Mine Pit);

Chimpanzee Habitat Area (4.3 km from Mine Pit);

Linguekoto (4.5 km from the Mine Pit); and

Dalakoy (4.7 km from the Mine Pit).

Blasting will occur in the daytime, where human activity levels are high. The timing of blasting in the daytime

means that noise levels will not exceed IFC night-time criteria in villages and sensitive receptor areas. The

noise modelling indicated that, in the absence of mitigation, the peak noise levels at Tambanoumouya Village

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FINAL 9-65

will exceed IFC daytime criteria under worst-case atmospheric conditions at the start of the Operation Phase

(in the absence of attenuation from the pit). Daytime noise criteria are not expected to be exceeded at other

villages in the surrounding area pre-mitigation. Following development of the pit, noise levels are not

expected to exceed IFC daytime criteria at any of the sensitive receptors surrounding the PDA. At this stage

of the Project, noise from blasting is expected to only be perceptible for sensitive receptors nearby under

certain atmospheric conditions (inversion, down wind, very high temp/high humidity etc.).

Haul Roads and Mine Access Road

The factors that affect noise emissions from traffic include the volume of traffic, the speed of traffic and the

composition of traffic (number of heavy vehicles versus light vehicles). Generally, heavier traffic volumes,

higher speeds and a larger number of heavy vehicles results in more traffic noise. The dB Foresight screening

model was employed to estimate the traffic-related noise from the Main Access Road. This modelling

indicated that there is the potential for Minor noise impacts on Linguekoto and Tambanoumouya Villages

due to their location less than 1 km from the Main Access Road. Noise impacts from road use during Project

phases will vary depending on the prevailing meteorological conditions and surrounding topography.


During the decommissioning/closure phase, the noise impact to the local acoustic environment is expected

to be similar to that generated during the Construction Phase associated with general construction activities.

The predominant sources are expected to be from noise emitting equipment such as combustion engines of

diesel generators, pumps, trucks, dozers, and hydraulic excavators for clearing the site.

Figure 9-12 Pre-mitigation predicted Construction Phase noise in Project Development Area – not including roads.

The units of contour values are dB(A)

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Figure 9-13 Pre-mitigation predicted Operation Phase noise in Project Development Area (including blasting),

prior to pit development. The units of contour values are dB(A)

Figure 9-14 Pre-mitigation predicted Operation Phase noise in Project Development Area (including blasting),

after pit development. The units of contour values are dB(A)

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Figure 9-15 Pre-mitigation predicted “Typical” Operation noise in Project Development Area (without blasting),

after pit development. The units of contour values are dB(A)

Figure 9-16 Pre-mitigation predicted Closure Phase noise in Project Development Area (after pit development).

The units of contour values are dB(A)

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In accordance with the WB/IFC EHS Guidelines – Noise Management 2007, the following control hierarchy will

be adopted for noise mitigation and management, to the extent practicable:

Elimination of the noise source;

Substitution with quieter equipment/process;

Engineering noise controls at the source;

Treatment of the noise propagation path; and

Installation of noise mitigation controls at the receiver.

Avoidance

The Project has been designed to avoid noise impacts, to the extent practicable. The following design

components will significantly reduce potential impacts for sensitive receptors:

The construction of the Main Access Road to connect the Project to RN7, avoiding primary residential

zones, will minimise the impact of noise emissions associated with road traffic.

An exclusion zone (PDA) will prohibit establishment of new settlements near the Project to limit noise

impacts on residential areas;

High noise emission equipment and infrastructure are located as far as practicable from potential

sensitive receptors;

Appropriate technology, that minimises sound emissions have been selected, wherever possible; and

Additional technologies will be selected (refer to Operation, Section 9.9.2) to further mitigate potential

noise impacts.

Minimisation

The following measures will be adopted to avoid potential of nuisance level noise impact:

Major noise emitting site activities will be restricted to daytime hours when human activity levels are

higher;

Operational blasting is planned to occur at 4 pm, when human activity levels are higher and blasting

noise is expected to be less noticeable above background noise levels;

Heavy machinery / equipment and the vehicle fleet will be maintained regularly to ensure they are in

good working order; and

Hearing protection will be provided to Project personnel working in the vicinity of noisy construction

activities (i.e. those generating noise levels greater than 80 dB(A)).

For Project vehicular traffic, additional management measures will be implemented to minimise potential

noise impacts, including:

Heavy vehicles will be restricted to approved construction haul routes only and to daytime utilisation

(to the extent practicable);

Vehicle speed limits will be enforced through village / settlement and environmentally sensitive areas

along transport routes;

The use of air brakes in village / settlement areas will be prohibited; and

Road surfaces will be regularly maintained to minimise surface unevenness, particularly where they

pass through/near residential areas.

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During Project operation, measures employed during the Construction Phase will be continued where

appropriate. Additional management and mitigation measures to minimise potential nose impacts during

operation include:

Select equipment with lower sound power levels, whenever possible, in the Project design;

Apply noise reduction, sound insulation and absorption for different equipment and operation;

Ensure the impedance mufflers and vibration insulating base are installed on the air compressors,

blowers and induced fans;

Apply sound insulation covers/barriers where appropriate;

Install high noise equipment (such as crusher) in separate sound insulation areas;

Install silencers for fans;

Install suitable mufflers on engine exhausts and compressor components;

Install acoustic enclosures for equipment casing radiating noise;

Improve the acoustic performance of constructed buildings, apply sound insulation;

Limit the hours of operation for specific pieces of equipment or operation, especially mobile sources

operating through community areas;

Avoid blasting during unfavourable atmospheric conditions (e.g. low level inversions), where possible;

and

Reduce Project traffic through community areas wherever possible.

Refer to Section 9.11 for additional management measures to manage noise impacts from blasting practices.


Noise impacts to the surrounding environment during Decommissioning / Closure are expected to be very

similar to the Construction Phase, thus the same proposed mitigation and management measures for

Construction are to be employed, where appropriate.

Progressive rehabilitation and revegetation activities will result in natural noise attenuation for sensitive

receptors over the Project life, and particularly during the Decommissioning / Closure Phase when most

revegetation activities will occur. Detailed strategies are provided in Volume E, Rehabilitation and Conceptual Mine Closure Plan.


The measures integrated into the Project design will avoid and minimise construction and operational noise

impacts, to the extent practicable. The proposed avoidance, mitigation and management measures for the

Project are expected to be effective at reducing the residual noise impacts on the surrounding environment.

During the Construction Phase, Minor temporary noise impacts for some households directly along the road

in Mako and Linguekoto may occur during the upgrade of Mako-Tambanoumouya road. Utilisation of the

current road infrastructure, while the Main Access Road is constructed, could also result in Minor noise

impacts for these households. With diligent application of prescribed management measures, noise impacts

for other sensitive receptors in the vicinity of the Project are expected to remain below relevant criteria.

During the Operation Phase, if management and mitigation measures are effectively implemented there is

expected to be Negligible noise impact on sensitive receptors surrounding the PDA from Mine Pit blasting,

mining and processing activities. Noise from blasting will occur in the afternoon on days when blasting is

conducted. This noise is likely to be perceptible at most sensitive receptors within 5 km, but is not expected to

exceed daytime noise criteria or result in any significant nuisance noise impacts for local villages.

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There is the potential for Minor noise impacts for Linguekoto Village from truck/vehicle use along the Main

Access Road. This village is located approximately 700 m from the closest point of the road. While the Project

traffic volume on the Main Access Road will be greatly reduced in the Decommissioning / Closure Phase,

some Minor impacts from passing vehicles may continue to occur for Linguekoto. Noise impacts during

Project phases at all receptors will vary depending on the prevailing meteorological conditions and

surrounding topography. Four other villages (Tambanoumouya, Wassadou, Dalakoy and Kerekonko) are

located within 1.5 km of the Main Access Road. Monitoring will therefore be required at these villages to

determine if noise impacts occur, and adapt management measures accordingly.

Negligible noise impacts are expected to occur for other sensitive receptors in the broader area surrounding

the Project during the Operation and Decommissioning / Closure Phases.

The key expected residual impacts related to noise under normal operating conditions, and their overall



Table 9-21 Summary of key expected pre-mitigation impacts, mitigation measures and residual impacts related to

noise for each Project phase


Significance




Noise (for Mako and Linguekoto Villages)

MODERATE


Major noise emitting site construction activities will be restricted to daytime hours when human activity levels are higher

Heavy vehicles will be restricted to approved construction haul routes only and to daytime utilisation (to the extent practicable)

Vehicle speed limits will be enforced through village / settlement and environmentally sensitive areas along transport routes

Road surfaces will be regularly maintained

Noise monitoring.

MINOR

Construction and upgrades of the Project Access Roads and utilisation of the current road infrastructure

Construction Phase noise emissions will be temporary (approximately 18 months), localised in nature, and short-term.

Noise (for other sensitive receptors within 5 km)

MINOR

NEGLIGIBLE

With diligent application of prescribed management measures, potential daytime noise impacts are expected to remain below relevant criteria

Operation

Noise (Linguekoto Village)

MODERATE


Noise monitoring

MINOR

Potential for Minor noise impacts from vehicle use on Main Access Road

Noise from blasting is likely to be perceptible, but is not expected to exceed daytime noise criteria or result in any significant nuisance noise impacts

Noise (other sensitive receptors within 5 km)

MINOR

NEGLIGIBLE

With diligent application of prescribed management measures, potential noise impacts are expected to remain below relevant criteria

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Significance




Noise from blasting is likely to be perceptible, but is not expected to result in any significant nuisance noise impacts


Noise (Linguekoto Village)

MODERATE As per Pre-Construction / Construction Phase

Revegetation activities conducted in accordance with Rehabilitation and Conceptual Mine Closure Plan


MINOR

Potential for Minor noise impacts from occasional vehicle use on Main Access Road

Noise (other sensitive receptors)

NEGLIGIBLE

NEGLIGIBLE

With diligent application of prescribed management measures, potential daytime noise impacts are expected to remain below relevant criteria

9.10 Vibration and Airblast


Anticipated vibration levels for airblast and ground vibration from blasting in the Mine Pit were calculated for

the applicable social receptors (local villages and workforce accommodation). Details are provided in the Air Quality, Noise and Vibration Baseline and Project Modelling report (Volume A, Appendix 4).

The impacts from continuous or impulse vibration may be a nuisance for local residents of the region /

additional biological receptors and in extreme cases can compromise the structural integrity of structures.

Both ground-borne and air-borne vibrations will be generated from Project activities during construction,

operation and decommissioning. These will primarily be emitted from:

Heavy vehicle traffic (which varies with speed and surface evenness);

Construction activities (e.g. grading, excavating); and

Blasting in the Mine Pit, quarries, or for road construction.

Vibration impacts to the surrounding physical area are expected to be predominantly short-term and

localised to the construction work areas and the mining and processing area. Potential impacts, if realised, are

expected to be nuisance level for a short duration, associated with blasting activities.

There are no applicable international guidelines or national standards applicable to the Mako Gold Project for

vibration from blasting, nor international guidelines for human comfort level. The Australian Standard

AS2187.2 provides guidelines for blast-induced vibration effects (AS 2187.2 App J, 2006) based on the US

Bureau of Mines USBM RI-8507 and British Standard BS 7385-2 and provides guidelines for assessing airblast

and vibration, including consideration of nuisance level impacts and management. The ESMMP (Volume C)

provides recommendations for Project adoption of appropriate guidelines for vibration.


Mine infrastructure

Ground vibration during construction of mine infrastructure will be localised and the potential impacts are

considered Negligible for the closest receptors. Ground vibration due to pit blasting at Petowal was

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calculated to be imperceptible in the nearest residential areas therefore potential impacts are considered

Negligible.

Transport infrastructure

During road construction and upgrade, nuisance level vibration impacts may occur in areas directly adjacent

the road. A vibratory roller creates typical Peak Particle Velocity (PPV) as follows;

2.4 mm/s at 10 m;

1.2 mm/s at 20 m; and

0.8 mm/s at 30 m from the road.

While this is likely to result in localised vibration impact, this will be temporary and may produce short-term

nuisance level impacts. Vehicle traffic can also result in vibration impacts. The factors that affect vibration

levels from traffic include the composition (heavy vehicle to light vehicle), volume and speed of traffic, road

surface condition and the transmission path (distance, topography between the source and the receiver).

While traffic-related vibration is unlikely to result in structural damage, it may create nuisance impacts.

Vehicle traffic induces vibration in two ways (Hajek et al. 2006):

Ground-borne vibration – caused by the dynamic impact forces of tyres on the pavement or other

surface that can propagate and excite building foundations, resulting in vibrations of building

components; and

Air-borne vibration – caused by low frequency sounds produced by engines and exhaust systems

(primarily associated with large diesel trucks) that can excite building components above ground.

Both types of vibration can be caused by the same vehicle at the same time. The generation of ground-borne

vibration is strongly linked to surface evenness – the more uneven the surface, the greater the ground-

vibration. Heavier vehicles typically produce higher ground-borne and air-borne vibration, and an increase in

the number of heavy vehicles tends to result in more vibration peaks, but not necessarily higher peaks.

Higher speeds increase both ground-borne and air-borne vibrations.

The Peak Particle Velocity or PPV for vehicle traffic can be estimated using a standard curve. For a passing

heavy vehicle (such as those which frequently travel on National Road 7), this curve indicates PPVs of

approximately;

2 mm/s at 5 metres from the road;

1.5 mm/s at 10 metres from the road;

1 mm/s at 15 metres from the road, and

0.2 mm/s at 45 metres from the road

Implementation of management measures for minimising traffic vibration will minimise the overall impact of

vibration from traffic. While uncertainty remains regarding residual vibration impacts from Project vehicles,

the assessment indicates that traffic vibration may be at nuisance levels (using the NSW Vibration Criteria for

residential areas at night) potentially up to 50 m from the Main Access Road and National Route 7.

This is likely an overestimate of expected impacts associated with the Project as this curve is based on

maximum recorded vibrations along a busy highway in the United States. These levels are not considered

sufficient to cause structural damage in the PDA or neighbouring communities.

Operation

During operation, the primary sources of Project related vibration will include:

Blasting in the Mine Pit;

Ore crushing at the ROM Pad; and

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Vehicular traffic.

Blasting during Project operation for ore extraction in the Mine Pit will generate the most vibration impacts,

including airblast and ground vibration. Blasting is an ‘impulsive’ vibration source characterised by a

succession of brief vibration periods that can significantly exceed the background level. The use of explosives

creates airborne pressure fluctuations (airblast) which are audible and can be perceived as ‘noise’ when in the

higher frequency range. At frequencies lower than approximately 20 Hertz, the sound energy is inaudible but

is capable of causing air vibration impacts.

The airblast levels from a blast received at a given location depends on many factors, including:

Charge mass;

Stemming height and type of stemming;

Burden;

Blast hole spacing, blast initiation sequence and timing delay between holes;

Ratio of the blast hole diameter to the burden;

Face height and orientation of face;

Topographic shielding;

Distance from the blast; and

Meteorological conditions.

Airblast vibration impacts were predicted using equations supplied by the US Department of Mines. Given

the distance between Mine Pit, construction area and current residential areas, air vibrations are not likely to

exceed the recommended maximum limit of 120 dB(L) - decibels linear. Airblasts may potentially startle

livestock and wildlife, or rattle windows, and sensitive species may move away from PDA. If managed

appropriately, there are not likely to be any significant impacts from airblast on the residents or structures

within nearby villages.

Ground vibrations as a result of blasting were calculated via an equation provided by the US Dept. of Mines.

According to this equation, ground vibration would be less than 0.1 mm/s beyond 1 km of the Mine Pit. Given

the distance between Mine Pit and current residential areas, ground vibrations as a result of blasting are not

likely to represent any significant impacts to the residents or structures in nearby villages.

Note however that the adopted human comfort level criterion (0.56 mm/s) is estimated to be exceeded

within 500 metres of the blast site, and that the building damage criterion (10 mm/s) is predicted to be

exceeded within approximately 50 metres of the blast site and thus should be considered an exclusion zone

for any site structures. Likewise the 50 metre radius would potentially represent a ground-vibration zone for

unstable rocks and vegetation.

Project related vehicular traffic will continue during operation, but will be confined to the Main Access Road,

WSD Access Road, and auxiliary roads between the Mine Pit, ROM Pad, WSD, Mine Services Area, etc. The

Mako-Tambanoumouya access road parallel to the Gambia (passing through Mako Camp as well as Mako and

Linguekoto Villages) is not expected to be utilised for Project activities during operation. General Project

traffic will not pass close to local villages along the Mako-Tambanoumouya access road, therefore associated

vibration impacts will not occur. Haul trucks may pass individual homes and villages on National Road 7

Traffic vibrations may be an issue up to an maximum distance of 50 m from the road, but would represent

only small percentage of daily vehicular traffic on RN7, and the additional impacts of the Project to existing

vibration levels are likely to be Negligible.


During the Decommissioning / Closure Phase, vibration impacts are expected to be Minor and Negligible

outside the immediate work areas. Vibration emissions during decommissioning/closure will primarily be

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associated with trucks and heavy vehicles used for decommissioning and removal of site components, and

rehabilitation of the site.


Avoidance

Project facilities are located at a sufficient distance from local residential areas to avoid potential vibration

impacts from all but airblast vibration from the Mine Pit. The following design components will significantly

reduce potential impacts for sensitive receptors:

The construction of the Main Access Road to connect the Project to RN7, avoiding primary residential

zones, will minimise the impact of vibration emissions associated with road traffic.

An exclusion zone (PDA) will prohibit establishment of new settlements near the Project to limit

vibration impacts on residential areas;

High vibration emission equipment and infrastructure are located as far as practicable from potential

sensitive receptors; and

Appropriate technology that minimises vibration emissions have been selected, wherever possible.

Minimisation

Potential impacts from construction related vibration will be minimised by:

Enforcing speed limits through residential areas;

Ensuring the road infrastructure surface is regularly maintained (particularly through residential areas);

and

Enforcing blast management measures (provided above for the Operation Phase work).

For blasting, the following measures are proposed for managing ground vibrations and air pressure overblast:

Ensure no explosive charge per blast hole exceeds the estimated maximum charge weight per delay;

Detonate only one charge per delay;

Check that the charge is able to break and displace its burden with reasonable ease;

Verify that burden distances are not too small;

Ensure premature ejection of stemming columns does not occur;

Place inter-row delays long enough to give good progressive relief of burden;

Detonate cord trunklines to fire pre-split blasts and ensure these trunklines have a core load of only 5

g/m ad are covered by at least 250 mm of sand or fine screenings; and

Review any reported structural damage from blasting activities.

The Project will undertake regular village consultations over the mine life. A qualitative assessment of

vibration impacts (nuisance level or structural damage) will be conducted via logging complaints as per the

Project Grievance Procedure (refer to ESMMP, Volume C). Such complaints will be reviewed and additional

management measures adopted, where required.


Management for the anticipated vibration levels generated during decommissioning activities will not

require additional management measures.

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During the Construction Phase, Minor temporary ground vibration impacts for some residences located

directly adjacent to the road in Mako and Linguekoto Villages may occur during the upgrade of Mako-

Tambanoumouya Road. Utilisation of the current road infrastructure while the Main Access Road is

constructed could also result in Minor vibration impacts for these houses.

With appropriate mitigation, there should be only Minor nuisance level impacts associated with airblast from

Mine Pit blasting within approximately 3km, and Negligible impact for receptors beyond this distance. This

impact will progressively decrease as the pit develops, as the pit walls will provide some natural attenuation.

With effective blast management, overall vibration impacts are considered Negligible during Operation.

Negligible vibration impacts are expected to occur for sensitive receptors in the Decommissioning / Closure

Phase, as no blasting will be required and the Mako-Tambanoumouya Road will not be used by Project

vehicles.

The key expected residual impacts related to vibration and airblast under normal operating conditions, and

their overall significance for each Project phase, are summarised in Table 9-22. Monitoring will be required

over the mine life to confirm the residual impact predictions, and allow management measures to be adapted

accordingly.


vibration and airblast for each Project phase

Receptor / Value


Significance




Vibration and Airblast

(Mako and Linguekoto Villages)

MINOR


Enforcing speed limits through residential areas

Ensuring the road infrastructure surface is regularly maintained (particularly through residential areas)

Regular village consultation and implementation of Project Grievance Procedure

MINOR

Vibration impacts mostly restricted to the immediate work areas

Minor temporary ground vibration impacts for some residences directly along the road in Mako and Linguekoto may occur during upgrade of Mako-Tambanoumouya road

Utilisation of the current road infrastructure while the Main Access Road is constructed could result in Minor impacts for villages along the Mako-Tambanoumouya road


(other Project-affected villages)

NEGLIGIBLE

NEGLIGIBLE

Vibration impacts will be Negligible

Negligible impact expected at sensitive receptors

Operation


(at villages within 3 km)

MODERATE As per Pre-Construction / Construction Phase

For blasting, implement measures for managing ground vibrations and air pressure overblast

MINOR

Airblast vibration from Mine Pit / quarrying blasting is expected to result in Minor nuisance impacts for closest villages. This impact will progressively decrease as the pit develops.


(other Project-affected villages)

MINOR NEGLIGIBLE

Vibration impacts will be Negligible


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Receptor / Value


Significance





NEGLIGIBLE As per Pre-Construction /

Construction Phase

NEGLIGIBLE

Vibration impacts restricted to the immediate work areas

Negligible impact expected at sensitive receptors

9.11 Flyrock


Blasting of ore and rock during the mining process can generate flyrock, rock fragments that may be

propelled through the areas surrounding the blast area, comprising a safety hazard people in proximity to

blasting.

The Company will develop a Blast Management Plan prior to construction that further specifies contractor

requirements. Implementation of the PDA and prohibition from entry to the PDA prior to blasting is

expected to reduce the potential safety hazard associated with flyrock to Negligible.


Avoidance

Blasting may be required for the construction of the access roads within the PDA. Blasting will not be

conducted within 500 m of residential areas. A temporary exclusion zone will be enforced surrounding any

site where blasting will occur. As per the Operation Phase blasting (refer to below), a communication protocol

will be established whereby neighbouring villagers will be informed of the timing of upcoming blasting. The

500 m (radius from the blast site) exclusion zone will be surveyed prior to blasting, and access roads blocked.

A sounding horn will be activated prior to the blast at an agreed-upon interval (in consultation with local

communities).

The following will be considered in selecting the blast contractor:

A licensed and competent blast contractor will be selected that has sound reputation and track record

with respect to blast practices;

Proposed blasting practices will be consistent with industry standards; and

Contractor’s staff are trained and competent and all systems and procedures are strictly followed.

Minimisation

The PDA will be enforced, ensuring access is prohibited (to all but applicable Project personnel) from an

exclusion zone of at least 500 m around the pit to protect people and structures from flyrock. Security

personnel will be employed at key Project access points (road infrastructure) to prohibit access via the most

obvious routes.

Additional measures to minimise potential flyrock impacts during Project operation include:

Blasting will occur only during established daytime hours (e.g. between 7 am to 6 pm);

Blasting will be conducted in favourable weather conditions;

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Blast area exclusion zones will be surveyed prior to blasting to ensure unauthorised people are not

within the potential risk area;

A procedure will be developed for informing villagers / Project personnel of the blasting schedule,

including: signage in villages with blasting dates / times or notification of blasting schedule at least 24

hours in advance of activity, and utilisation of a sounding horn that will warn people in the region of an

impending blast (e.g. sounded 15 minutes in advance of blasting and 5 minutes in advance of blasting)

(refer to ESMMP, Volume C);

Blast pattern designs and powder factors will be evaluated to ensure they are sufficient to provide the

required fragmentation while minimising the potential to cause damage to pit walls and infrastructure;

Flyrock will be visually monitored to confirm that the exclusion zone is sufficient to protect sensitive

receptors (biological and social);

Regularly employ blasting experts to provide audits and advice on general and specific blasting issues;

and

Train Project staff on fly rock safety and conduct a public education program regarding community

safety issues associated with blasting.

The above controls should be considered for inclusion in a Blast Management Plan. This Plan would provide

the detailed management and communication procedures to be employed prior to any blasting to avoid

potential flyrock impacts.


No blasting is required during Decommissioning/Closure, therefore management measures are not required

for this phase.


With strict adherence to flyrock management and mitigation measures detailed above, the expected risks will

be minimised to within acceptable limits.

The key expected residual impacts related to flyrock under normal operating conditions, and their overall




flyrock for each Project phase

Receptor / Value


Significance




Flyrock MINOR

Preparation of Blast Management Plan

The PDA will be enforced, ensuring access is prohibited

Blasting will occur only during established daytime hours

Blasting will be conducted in favourable weather conditions

Blast area exclusion zones will be surveyed prior to blasting to ensure unauthorised people are not within the potential risk area

Flyrock monitoring

NEGLIGIBLE

Management and mitigation measures implemented are expected to reduce the potential safety hazard associated with flyrock to Negligible

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Operation

Flyrock MINOR


A procedure will be developed for informing villagers / Project personnel of the blasting schedule

A sounding horn will be activated prior to the blast at an agreed-upon interval (in consultation with local communities)

NEGLIGIBLE

No blasting expected outside of PDA

Prohibition from entry to the PDA prior to blasting is expected to reduce the potential safety hazard associated with flyrock to Negligible


Flyrock NEGLIGIBLE None required NEGLIGIBLE

No blasting expected to be required

9.12 General Waste and Hazardous Materials


Construction, operation and decommissioning / closure of the Project will require or generate hazardous and

non-hazardous materials. The Project has been designed to specifically address potential risks associated

with hazardous / non-hazardous materials during transport, storage, handling and disposal.

Waste

Potentially hazardous materials that will be stored and handled on site include:

Cyanide (1 tonne bulk bags);

Cyanide reagent packaging (wood and plywood bulk-boxes, < 100 kg/week)

Additional Process Plant reagents (refer to below);

Oils, solvents, and other hydrocarbons (diesel);

Truck wash sludge (<10 m3 per week);

Waste oil (approximately 1,000L/week);

Medical waste including sharps, bandages, etc.; and

Sewage and greywater from kitchens and toilets (refer to Section 9.6).

Non-mining (general non-hazardous) waste materials will be generated via Project construction activities,

administration, procurement and general comp maintenance and operation, including:

Non-toxic solid reagent polypropylene or similar packaging (< 100 kg/week) and grinding media

packaging (200 L steel drums, 50 per week);

Construction material excess (various, approximately 10 tonnes per day), scrap timber (< 2m3 per week),

scrap metals (< 2m3 per week);

Domestic waste (e.g. bottles, cans, plastics,< 2m3 per week);

Putrescible waste (e.g. kitchen waste and food scraps, 250 kg per day);

Liquid reagent packaging (200L plastic drums, 20 per week);

Office waste (e.g. paper, etc., 250 kg per day); and

Other domestic waste (< m3 per week).

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Non-hazardous waste will be handled and disposed of accordingly:

Office waste (~250 kg per week of paper, etc.) will be disposed of in the lined landfill;

Other domestic waste (bottles, cans, plastics (<2 m3 per day), scrap timber (<2 m3 per day), and scrap

metals (<2 m3 per day) will be recycled, with the remainder disposed of in the lined landfill;

Non-toxic solid reagent packaging (< 100 kg per week) will be disposed of in the lined landfill;

200 L steel drums from grinding media packaging (50 per week) will be recycled;

200 L plastic drums (20 per week) will be recycled if possible or disposed of in the lined landfill; and

Cyanide reagent packaging (< 1,000 kg per week of wood and plywood bulk-boxes) will be burned,

with disposal of ash transported to the lined landfill.

Table 9-24 provides an overview of the various types of waste expected to be generated through the Project

activities as well as the preferred method of disposal for each waste stream. The Project will not generate any

radioactive waste.

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Table 9-24 Summary of major waste streams

Waste Stream Nature Quantity Method of Disposal in

Order of Preference

LIQUID WASTE

Mine services area

waste water

Truck wash water <50 m3/day Used for dust suppression

on haul roads

Truck wash sludge Hydrocarbon contaminated

sludge from truck wash

sump

<10 m3/week Hydrocarbons to be

returned with recycled oil

products to supplier

Solids disposed of in WRD

or TMF

All water to be directed to

TMF for treatment

Sewage treatment

plant (STP) sludge

Surplus activated sludge

from all sewage treatment

plants

<50 kg/d Direct landfill burial

STP treated water:

accommodation camp

Treated water from camp

sewage treatment plant

50-100 m3/d Leach drains

STP treated water:

plant site and mine

services area

Treated water from plant site

sewage treatment plant

50-100 m3/d Disposal to TMF and

recovered for use as

process water

Waste oil Used lubricating oil etc 1,000 L/week Recycle

SOLID WASTE

Putrescible waste Kitchen waste and food

scraps etc

250 kg/day Landfill

Office waste Paper etc 250 kg/week Landfill

Other domestic waste Bottles, cans, plastics <2 m3/day Recycle

Balance to landfill

Construction waste Various categories 10 t/day Sorted in accordance with

types below and disposed

of in a similar manner

Inert concrete waste Decommissioning of built

infrastructure

6000 m3 Disposal to WRD

Scrap timber Packaging, scrap pallets, off

cuts etc.

<2 m3/week Recycle

Landfill

Scrap metals Scrap equipment and parts,

steel off cuts etc.

<2 m3/week Recycle

Landfill

Non-toxic solid

reagent packaging

Polypropylene or similar

bags

<100 kg/week Landfill

Grinding media

packaging

200L steel drums 50/week Recycle

Liquid reagent

packaging

200L plastic drums 20/week Recycle

Landfill

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Waste Stream Nature Quantity Method of Disposal in

Order of Preference

Cyanide reagent

packaging

Wood and plywood bulk-

boxes

<1,000 kg/week Incineration and dispose of

ashes to landfill

Contaminated soil Contaminated with

chemicals and / or oil spills

<1 m3/week average Disposal to TMF

Volatilise contaminants

then burial in lined landfill

Table 9-25 shows the principal waste disposal routes for different materials.

Table 9-25 Waste disposal routes

Waste classification Example Disposal route

Hazardous - Medical/ biohazard Clinical waste Incineration

Hazardous – high risk Oil filters, waste oily rags Removal of recyclable parts where possible, then incineration. Ash/scrap to lined landfill pit. More detail is provided in the ESMMP

Hazardous – low risk Non-compostable food wastes Lined landfill pit within PDA

Hazardous – low risk Non-recyclable domestic waste and recyclables, including empty bottles, cans, and plastics

Disposed of in off-site landfill pits or recycled wherever possible

Non-hazardous Non-recyclable domestic waste and recyclables, including empty bottles, cans, and plastics

Unlined landfill pit where not recycled or composted

Hazardous Materials and Waste

Sewage Treatment Plant

A Sewage Treatment Plant will be used to treat both waste water and raw sewage from various sources,

including toilets, showers, basins and kitchen facilities.

Both plant and accommodation sites will use a Biological / Aeration based treatment system incorporating

chlorine sterilisation before discharge. Plant water will be disposed of via the tails hopper to the TMF. Camp

water will be disposed of via leach drains. Solids will be disposed of via solar drying and burial in lined landfill,

or sewage truck.

Hazardous Materials

Cyanide

Cyanide may be released to the receiving environment (in gaseous or liquid form) during: transport to the

mine, storage or handling, processing, piping to the TMF, and / or from TMF supernatant water. The potentially

deleterious impacts of cyanide releases (in variable form) are well documented. Potential impacts to aquatic

and terrestrial biology are discussed in the Biological Impacts chapter (Chapter 10) and to human health in

the Social Impacts chapter (Chapter 11).

The toxicity of cyanide depends on the form of cyanide present, ranging from the highly toxic ‘free cyanide’

(CN+HCN) to non-toxic or less-toxic stable strong complexes. The most relevant forms of cyanide with

respect to Project operation may include:

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Hydrogen cyanide (HCN) in gaseous phase, which may result from volatilisation of sodium cyanide at

low pH. HCN is a dangerous gas in a closed system such as the Process Plant. When mixed with water,

sodium cyanide will volatilise at pH < 11;

Free cyanide, potentially derived from dissolution of iron-cyanide complexes that decompose in the

presence of sunlight (releasing free cyanide) in the TMF reservoir;

Weak acid dissociable cyanide (WAD cyanide), ionic complexes of varying stability comprised of

cyanide and one of a number of metals. Various WAD cyanide complexes are relatively unstable (e.g.

copper and zinc) and may release cyanide back to the environment; and

Potential bi-products of cyanide destruction (e.g. Cyanate and Thiocyanate) in the slurry gravitated

from the cyanide destruction circuit (in piping and TMF supernatant water).

Additional sources of potential cyanide release to the environment include: an accidental release during

transport storage and handling; spill or leakage of cyanide solution during preparation and handling; and/or

during piping of slurry to the TMF, posing a threat to water quality and air quality along the transport corridor

and storage complex. Packaging material for NaCn may also be a source.

Reagents

Process Plant reagents (sodium hydroxide, hydrochloric acid, copper sulphate, sodium metabisulphite, leach

aid, calcium carbonate, activated carbon, and flocculent) and their packaging materials are a potential threat

to surface and groundwater quality if released to receiving waters (refer to Section 9.8) and in some cases

may impact air quality if ignited (refer to Section 9.13).

Hydrocarbons

Diesel fuel will be utilised for vehicles / equipment / processing and for the Power Station. Accidental release

of hydrocarbons would potentially impact receiving waters (ground and surface water) and soil substrate.

Hydrocarbons are also a fire hazard (refer to Section 9.13), which threatens Occupational Health and Safety as

well as air quality in general.

Medical Waste

Sharps, bandages, etc. are potential vectors for the spread of disease.

Non-Hazardous Waste

General waste materials generated from mining construction or operation, workforce accommodation camps

and administrative facilities, Process Plant, etc. may physically impact the environment (with potential

biological / social implications), including: contamination of receiving surface and groundwater for

improperly stored or untreated wastes (refer to Section 9.8); increased populations of wildlife due to food

wastes, including rats and other potential vectors for disease; and impaired visual amenity. The non-

hazardous wastes listed in Section 9.12.2 will be generated during Project construction, operation and

closure.


Avoidance and Minimisation

The Process Plant areas and Mine Services Area will be constructed with concrete slabs, primary containment

bunds that can contain at least 110% of the volume of hazardous and non-hazardous materials in the storage

areas, and sump pumps to recover any spilled material.

Spillage in the Process Plant that occurs outside of the Process Plant bunds will report to an event pond

(secondary containment), with water and contaminants reclaimed by a submersible pump.

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The amount of cyanide, additional processing reagents, and diesel stored on site will be minimised via

reconciliation of volume requirements. On an instantaneous basis, reagent usage rates of cyanide, elution

and detoxification reagents and diesel flow rates to unit operation will be measured and delivery receipts and

stock takes accounted to ensure adequate but not excessive hazardous materials storage at the Process Plant,

Mine Services Area, vehicle laydown areas, etc.

Cyanide

The Project is designed to avoid potential cyanide releases via the following design elements and

management measures:

Cyanide transport: The Project will adhere to ICMI Cyanide Management Code (Cyanide Code)

Principles and Standards of Practice for cyanide transportation (refer to below), including independent

auditing of procedures, Transportation Verification Protocols);

Storage and handling: The Project will adhere to Cyanide Code Standards of Practice for handling and

storage.

Cyanide destruction: The Process Plant will incorporate a cyanide destruction circuit to treat slurry

from the CIL circuit, gravitated from the carbon safety screen to the cyanide destruction circuit feed

box. Cyanide destruction will be carried out using the air / SO2 process. The cyanide destruction circuit

will comprise two tanks capable of operating in series or parallel. Slurry pH will be adjusted using

caustic solution metered into the circuit. Copper sulphate and sodium metabisulphite solution will be

added to the circuit using dedicated variable speed dosing pumps. Dedicated low pressure blowers

will supply air to the destruction tanks. Cyanide destruction circuit tailings will be pumped to the TMF.

Supernatant water will be recovered from the TMF and returned as process water decant return to the

Plant for storage in the process water tank and reuse;

Piping to the TMF: CIL tailings will be pumped to the TMF. The tailings line will be contained within a

trench to minimise potential contamination from pipe leakage. The route will have a continuous

downhill slope to the TMF with no ‘dead legs’ in the line requiring drain valves and scour pits.

The Company will adhere to the International Cyanide Management Code (a voluntary initiative), including

the following ICMI Principles (ICMI, 2014):

Production: Encourage responsible cyanide manufacturing by purchasing from manufacturers who

operate in a safe and environmentally protective manner;

Transportation: Protect communities and the environment during cyanide transport;

Handling and Storage: Protect workers and the environment during cyanide handling and storage;

Operation: Manage cyanide process solutions and waste streams to protect health and the

environment;

Decommissioning: Protect communities and the environment from cyanide through development

and implementation of decommissioning plans for cyanide facilities;

Worker Safety: Protect workers’ health and safety from exposure to cyanide;

Emergency Response: Protect communities and the environment through the development of

emergency response strategies and capabilities;

Training: Train workers and emergency response personnel to manage cyanide in a safe and

environmentally protective manner; and

Dialogue: Engage in public consultation and disclosure.

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Hydrocarbons

Diesel fuel, hydraulic fluids and other hydrocarbons required for vehicle / equipment operation will be

transported, stored and handled to minimise the potential for accidental discharge and to avoid potential for

significant physical impacts (refer to Volume C, ESMMP for greater detail). In summary, the following

measures will be employed:

Vehicle maintenance will be conducted on concrete slabs with diversion drains directing surface flow

to oil / water separators prior to discharge to the surrounding environment;

Hydrocarbons will be stored in primary containment bunds that can accommodate at least 110% of

the volume of hydrocarbons stored on-site;

Hydrocarbon storage areas and vehicle maintenance areas will be stocked with spill clean-up materials

(e.g. Sorbex);

Hydrocarbons storage areas and containers will be labelled, including clearly labelled and displayed

Material Safety Data Sheets (MSDS); and

Personnel will be trained in storage, handling, spill prevent, and spill treatment measures and will be

provided with appropriate personal protective equipment (PPE).

Waste oils will be collected at source and transferred into secure, bunded tanks. Waste oils tanks will be

periodically collected by the supplier and returned through their logistics chain for recycling.

Additional Process Plant Reagents

The Process Plant will be designed with the following measures to account for potential contaminant

discharge of processing reagents (refer to Section 9.6 for greater detail regarding surface water quality):

Materials handling, containment and bunding in all Plant areas will meet legislative requirements;

Plant areas subject to potential contamination from chemical or slurry spills will have concrete slabs

and bund. Bunded areas will be equipped with sumps to recover spilled material and rain from slabs;

Spillage exceeding the capacity of bunds will report to the HDPE lined event pond; and

Fire water for the process plant will be drawn from the raw water tank (with a reserve of fire water in

the tank always available); an electric fire water delivery pump and back-up diesel driven fire water

pump to convey water; and hydrants and hose reals throughout the Process Plant (including the fuel

and reagent storage areas) to avoid hazardous material air emissions via burning (refer to Section 9.13).

General Management and Mitigation Measures for all Hazardous Materials

Management and mitigation measures for hazardous materials include:

Maintaining an inventory of hazardous material on site;

Construction of an appropriately designed and clearly marked hazardous storage facility;

Provision of protective equipment (i.e. gloves, plastic coveralls, safety glasses and self-contained

respirators) and clean-up materials (e.g. Sorbex);

Clearly labelled and displayed MSDS for all hazardous materials on site;

Comprehensive training for process operators regarding emergency response and the handling,

storage and use of hazardous materials; and

Development of emergency response procedures and training for all Project personnel.

Further detail regarding the management of waste and hazardous materials is provided in the ESMMP

(Volume C). A framework for emergency response procedures is also provided. The Company will develop

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Emergency Preparedness and Response Plans that will provide site-specific management plans, emergency

response protocols, and training requirements.

General (Non-Hazardous) Waste

Waste management at the Project will require the construction of several facilities (e.g. storage and

separation area for recyclables, residue waste landfill for non-recyclables and non-hazardous materials. Inert

construction waste will be disposed of at the WRD.

In general, the Company will handle waste disposal according to the procedures outlined below.

General Procedures

The waste management procedures for the Project will be based on the following hierarchy (in decreasing

order of preference):

1. Minimise the production of waste;

2. Maximise waste recycling and reuse;

3. Treatment of waste; and

4. Ensure safe waste disposal.

The first priority for the management of non-mining wastes generated by the Project will be to reduce the

volume of waste generated, which will be achieved by:

Procuring supplies that produce less waste by virtue of the way they are produced, packaged or

consumed;

Procuring supplies that have been produced from recycled materials, if possible; and

Maximising the efficiency of all on site production processes.

To maximise recycling and reuse, waste will be segregated into different types at the location where they are

generated. Solid waste will be segregated into three categories as follows:

Biodegradable materials – vegetation and food scraps;

Recyclable materials – processed timber; hard plastic; glass; metal; paper and cardboard; and tyres.

(Waste will be further segregated within this category), depending on the requirements of recycling

contractors; and

Non-hazardous residue waste.

Any non-hazardous residue waste that cannot be reused or recycled will be deposited in clearly marked,

general litter bins located around the Project site. The Company will implement an education campaign for

staff and contractors to minimise the generation of litter associated with Project activities.


With effective implementation of the management and mitigation measures listed above, it is anticipated

that hazardous materials will not impact the surrounding environment under normal operating conditions.

In addition to the management and mitigation measures listed above, non-hazardous materials management

will require oversight from senior management. With proper disposal, monitoring, and continuous

improvement targets (refer to ESMMP), it is anticipated that impacts from non-hazardous materials will be

Negligible.

The key expected residual impacts related to general waste and hazardous materials under normal operating


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be required over the mine life to assess performance, and allow management measures to be adapted

accordingly.


general waste and hazardous materials for each Project phase

Receptor / Value


Impact Significance




General Waste and Hazardous Materials

MINOR

Maintaining an inventory of hazardous material on site

Construction of an appropriately designed and clearly marked hazardous storage facility

Provision of protective equipment and clean-up materials

Clearly labelled and displayed MSDS for all hazardous materials on site

Development of emergency response procedures and training for all Project personnel

Regular monitoring of compliance

NEGLIGIBLE

With effective implementation of the management and mitigation measures listed above, it is anticipated that hazardous materials and other wastes produced will not impact the surrounding environment.

Operation


MODERATE


Adherence to the International Cyanide Management Code principles and standards of practice

Comprehensive training for process operators regarding emergency response and the handling, storage and use of hazardous materials

NEGLIGIBLE




MINOR As per Pre-Construction /

Construction Phase

NEGLIGIBLE


9.13 Accidental Events and Natural Hazards


Accidental and natural events that could lead to hazardous discharges or emissions have been considered

throughout the ESIA. While the probability of these occurrences may be low for the majority or all of the

following potential impacts, Project design; management; monitoring; and emergency preparedness and

response procedures / training are required to minimise attendant risk and ensure appropriate action is taken

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in the event of an accident or natural hazard. Table 9-27 provides a summary of key risks and associated

management measures.

Table 9-27 Key Project risks associated with accidental events and natural hazards

Project Facilities (including Pre-construction)

Key Risks

Mine Pit

Pit edge crumble from structural instability leading top subsidence

Pit wall collapse from structural instability

Flyrock

TMF Contamination of surface and groundwater from excessive seepage

Failure of TMF embankment

Sediment Traps Failure of 1.5m embankment releasing sediment-loaded - possibly during a high rainfall event

Process Plant

Cyanide solution spill caused by human error and inadequate management of process water leading to surface and groundwater contamination

Overspill/level indicator malfunction – surface and groundwater contamination from cyanide spill

Mechanical failure / chronic loss of containment leading to cyanide leak

Ore and Waste Rock Haulage Collision with wildlife

WSD Provision of mosquito breeding area with associated increase in malaria incidence

Hazardous Material Storage / Handling

A spill or accidental release of a hazardous substance

Borrow area / Quarry Flyrock

Transportation Road Traffic Accidents – standard collision type accidents

RTAs - explosion or fire with associated secondary risks

The Risk Assessment (ESIA Volume B) provides further detail on each of these risks.

Accidental events and natural hazards may compromise the integrity of Project facilities, potentially resulting

in unanticipated discharge to receiving waters, pollutant emissions to the local atmosphere, landslips, etc.

Management and training requirements are provided in the Mako Gold Project ESMMP (Volume C). In

addition, MEC will develop site-specific Emergency Preparedness and Response Plans for the Mako Gold Project.

Important elements of the Plan includes undertaking regular risk assessment, ensuring adequate emergency

response measures / materials are in place (e.g. water for fire-fighting, spill adsorbent material, etc.), and

training of Project personnel regarding appropriate response to each potential event.

Emergency response to an environmental incident caused by an accidental event or a natural hazard will be

prioritised according to the following sequence:

1. Protection and rescue of human life;

2. Minimisation of the area impacted by the incident;

3. Protection of the environment, plant and property;

4. Rendering the area safe in which the emergency has occurred;

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5. Restoration of all disrupted services; and

6. Decontamination and rehabilitation of the incident scene and surrounding area.

Depending upon the severity of an environmental incident, emergency response may also involve using the

services of, or notifying, the following groups:

Police;

Site medical practitioners;

District and Regional Government;

Village Chiefs and local community;

Department of Civil Protection;

Fire services;

DEEC;

Department of Mines; and

PNNK Authority.

General safeguards that will be adopted and specified in the Emergency and Preparedness Response Plans

include induction training and periodic refresher training for all employees on all aspects of safety, including

site specific rules and emergency situations.

The following sub-sections provide an assessment of specific events and associated safeguards and control

procedures.

Pre-Construction / Construction and Operation

Fuel and chemical leakage or spill

Fuel and chemical spillage may occur during transport, handling, processing, etc. resulting in the release of a

hazardous substance to soil substrate, downstream / down gradient receiving waters, or the atmosphere.

The potential physical impacts to water quality, air quality, soil, and air quality are considered in Section 9.6

(Surface and Groundwater Quality), Section 9.12 (General Waste and Hazardous Materials), and Section 9.8

(Air Quality).

Flooding

Flooding from extreme storm events has the potential to impact the TMF, WSD, and WRD as each facility

intersects ephemeral drainages. The greatest hazard would occur from the failure or over-topping of WSD or

TMF dam structures (and subsequent failure) resulting in release of water and supernatant water (for the TMF)

to the downstream environment. Such failure poses a significant occupational health and safety risk for

construction / operation personnel, local inhabitants of the region, and aquatic / terrestrial ecology. A Dam

Break Consequence Assessment has been conducted for the Project and is appended to the Risk Assessment

(ESIA Volume B).

The Gambia River basin is subject to periodic flooding during the rainy season (refer to ESIA, Chapter 5). As

the majority of Project facilities will be situated outside of the Gambia River flood zone, impacts from Gambia

River flooding would predominantly be unchanged from pre-Project impacts (e.g. existing biological and

social aspects of the region).

However, components of the pumping station for the WSD and segments of the existing road network that

will be utilised during Project construction are situated within the 1000 year average return interval (ARI)

storm event flood area for the Gambia River and may therefore be compromised during an extreme storm

event (pumping station will be located above the 100 year 24 hour ARI storm event flood area. Associated

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potential impacts include erosion of road surfaces and sediment transport to receiving waters for an extreme

flood event. The pump station will be connected to mains power through the Power Station.

Figure 9-17 Estimated flood backflow conditions in Badalla Creek and the Gambia River near the PDA

Fire and Explosion

Mining and ore processing operation, including the improper storage, handling or transport of flammable

substances, can lead to the generation of potentially explosive and/or flammable gas emissions. Potential

impacts may include breakout of fire into surrounding areas, as well as release of significant quantities of air

pollutants and contaminated runoff from burnt areas.

The improper storage, handling or transport of explosives could result in an accidental explosion, potentially

causing loss of life and property damage.

Seismic Risk

A significant earthquake could lead to failure of TMF or WSD dam structures and release of water or tailings to

the downstream environment as well as landslips in the Mine Pit or constructed embankments. Sub-Saharan

Africa is largely a stable intra-plate region characterised by relatively low levels of seismic activity (refer to

Chapter 5) and the PDA is categorised as having a Very Low seismic hazard rating (PGA, 0 – 0.2 m/s2) (Global

Seismic Hazard Assessment Program, 1999).

Failure of Mine Pit walls

While there are no known large scale structures (faults, thrusts, shear zones) likely to affect the deposit, there

is a risk of pit slope instability due to such structures behind the pit wall. In addition, joint sets may be

missing which could impact the kinematic stability of some of the slope bench faces. Impacts would be

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confined to the Mine Pit area, with the greatest risk the occupational health and safety of Project personnel

working in the Mine Pit.

Waste Rock Dump Failure

The geotechnical stability of the WRD is not considered a critical issue due to the proposed low angle slope

design. The stability of the proposed WRD has been assessed under static and seismic loading conditions

using limit equilibrium methods. ‘SLOPE/W’ has been used for the analysis using the Morgenstern-Price

method of limit equilibrium method of analysis (Knight Piesold, 2015g). The modelling results indicate that

the WRD will possess adequate stability for the modelled scenarios and conditions. However, the results

identify that WRD stability is sensitive to the level of the phreatic surface and that drainage measures should

be provided to direct surface water away from the WRD, to reduce water infiltration and to reduce the level of

the phreatic surface that develops.

Dam Failure

A Dam Break Assessment was prepared for the Mako TMF and this resulted in a Dam Failure Consequence

Category of ‘High C’ as per ANCOLD 2012 guidelines. The Project has therefore adopted design criteria for the

TMF based on its Dam Failure Consequence Category. Stability failure due to a seismic event is not likely to

occur during the operating period and in the few years following decommissioning, a nominal period of 15

years. Thereafter the tailing mass will become less susceptible to failure as it consolidates and drains,

therefore resulting in an overall increase in strength.

Harmattan Winds – Dust storms

The Harmattan is a north-easterly wind that blows from the Sahara Desert into the Gulf of Guinea between

November and March, passing over the Project region. On its passage over the desert, the Harmattan picks-

up fine dust (e.g. < 10 µg) and can result in significant dust storms or sandstorms. During extreme events,

public health may be compromised as suspended particulate matter comprises a number of organic and

inorganic constituents, some of which may cause respiratory diseases as well as other health issues.

Drought

Senegal is frequently subjected to drought conditions. The significance of drought in greater Senegal

includes degradation of vegetation (natural ecosystems and agricultural / livestock grazing land), terrestrial

and aquatic biodiversity, and human resource extraction (e.g. agricultural products, NTFP, and water)

including financial implications and famine (refer to Chapter 5). However, the Kedougou region is the wettest

area in Senegal, with a mean annual rainfall of approximately 1,171 mm recorded between 1982 and 2011 in

Kedougou (SRK, 2013). The Project region is less prone to drought conditions and vegetation / habitat and

agricultural plots less likely to suffer significant set-backs.


Avoidance and Minimisation

Fuel and chemical leakage or spill

Project facilities that require storage and handling of hazardous materials (i.e. Process Plant and Rom Pad,

Mine Services Area, Power Station) have been designed with primary and secondary containment systems.

Processes and requirements for storage, handling, emergency preparedness and response (i.e. prevention,

clean-up, training requirements) as well as controls for transport of hazardous liquid materials is provided in

Section 9.12.

Project compliance requirements are also specified in greater detail in the ESMMP (Volume C). The ESMMP

broadly covers the management of potential liquid contaminants, including diesel, process reagents, waste

water, etc. The ESMMP provides requirements for the following categories:

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Primary containment system (i.e. bunding at storage and handling facilities);

Secondary containment systems (i.e. secondary bunds and drainage control);

Containment within operation area (i.e. for spills that occur away from containment structures such

as bunds but within the operation area (e.g. road infrastructure and Mine Pit);

Off-site spill (e.g. spills that occur during transport); and

Non-compliance discharge (i.e. spills that originate from within the Project Footprint and escape the

PDA to receiving environments).

Spill responses are sub-divided into two response categories:

Simple spills of benign chemicals that can be managed immediately by the person present on site

(these do not constitute an environmental emergency); and

More complex spills that may require additional resources or specialist skills for containment and

rehabilitation.

To respond quickly and appropriately to fuel and chemical leaks and spills, the ESMMP provides the

framework for emergency response and the Emergency Preparedness and Response Plans will outline specific

procedures (containment, provision of spill clean-up materials, staff training, and emergency response

protocol) for commonly used fuels and chemicals.

Flooding

The Project Footprint is situated above the Gambia flood zone for the 1000 year average return interval (ARI)

storm event, with the exception of an existing road that will be used during early stages of construction. The

road will be upgraded during early phases of construction, with improved erosion and sediment control

facilities incorporated. Some damage to the unsealed road (and associated erosion and sedimentation) from

an extreme flood event cannot be avoided. The pump station (designed for the 100 year flood level) will be

the subject of further design changes to confirm the final tower height to ensure it can withstand extreme

flood events.

As per Sections 9.2 - 9.4, the WSD and TMF embankments / dams have been designed to withstand

stormwater generated from 100 year 24 hour ARI storm events plus a contingency freeboard of 1m. The WSD

and TMF embankment slopes have been designed for geotechnical stability at full capacity. Spillways will be

constructed to accommodate stormwaters generated for >100 year 24 hour ARI storm events that will

discharge water into the Badalla Creek (TMF) and Kobokou Creek (WSD), to reduce the risk of overtopping.

Seismic events

The Project is committed to ICOLD guidelines with respect to designing the WSD and TMF dams for

geotechnical stability, which accounts for seismicity. ICOLD seismic design and performance criteria consider

various design seismic design criteria for different structures / elements of a large dam Project. Those

considered most relevant to the Mako facilities include:

The Safety Evaluation Earthquake (SEE), which is the earthquake ground motion a dam must be able to

resist without uncontrolled release of the reservoir. The SEE is the governing earthquake ground

motion of the safety assessment and seismic design of the dam and safety-relevant components,

which must be functioning after the SEE. SEE may be determined by assessing the Maximum Credible

Earthquake (MCE) and/or the Maximum Design Earthquake (MDE). Usually the most unfavourable

ground motion parameters are used (for MCE vs. MDE);

MCE is the event which produces the largest ground motion expected at the dam site on the basis of

seismic history and the seismotectonic conditions of the region. It is estimated based on deterministic

earthquake scenarios;

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MDE ground motion parameters are estimated based on a probabilistic seismic hazard analysis, with

mean values of ground motion parameters taken for 10,000 year events (or lesser for smaller dams);

and

Operating Basis Earthquake (OBE), may be expected to occur during the lifetime of the dam. No

damage or loss of service may occur. It has a probability of occurrence of approximately 50% during

the service life of 100 years. The return period is taken as 145 years (ICOLD, 2010). OBE ground motion

parameters are based on probabilistic seismic hazard analysis, with mean values utilised.

For the MCE analysis, the Project assumed that an event of 5.8 ML magnitude could occur at a distance of

250km from the site, which represents the approximate distance to the nearest cluster of historic events.

The design is for the embankments to be stable under design earthquakes up to a design acceleration of

0.03g during operation. The probability of failure is assessed on the basis of failure being the release of

tailings caused by a low probability seismic event. This is considered equivalent to a return period of 1 in

10,000 years or more (Knight Piesold, 2015k).

Mine Pit wall slopes / bench widths and WRD slope angles have considered seismicity into their respective

design. The peak horizontal rock ground motions are 0.03g and 0.10g for the Operating Basis Earthquake

(OBE) and Safety Evaluation Earthquake (SEE) events respectively. The stability of the proposed WRD has

been assessed under static and seismic loading conditions using limit equilibrium methods. The stability of

the WRD was assessed to confirm the factors of safety against shear failure considering long-term drained

conditions and seismic conditions. The desired minimum factor of safety for seismic activity during operation

(OBE) is 1.2 to 1.3 and for seismic activity post closure (SEE) the factor of safety is 1.1 (Knight Piesold, 2015j).

Fire

Fire suppression water for the Process Plant and Mine Services Area will be drawn from the raw water tank.

Suctions for other water services fed from the raw water tank will be at an elevated level to ensure a fire water

reserve always remains in the raw water tank. The fire water pumping system will contain an electric jockey

pump to maintain pressure, an electric fire water delivery pump to supply fire water at the required pressure

and flowrate and a diesel driven fire water pump will serve as a backup, automatically starting in the event

that the electric pump fails to maintain pressure in the fire water system. Additional measures include:

Fire hydrants and hose reels will be placed throughout the process plant, power station, fuel storage

areas, and plant offices at intervals that ensure complete coverage in areas where flammable materials

are present;

Operation and transport will avoid petrol and LPG where feasible, limiting risk from explosive materials

to blasting material (dynamite), and diesel fuel;

Appropriate Project personnel will be trained to fight fires (refer to Volume C, ESMMP); and

The explosives storage magazine will be located at least 800 m from all infrastructure and in areas

meeting international standards for fire safety (including fitting flame arresting devices).

Tailings Management Facility Dam Failure

In order to reduce flooding, overtopping and erosion, the TMF will have a stormwater interception and

diversion system. The design will include sufficient freeboard at all times to accommodate the probable

maximum precipitation (PMP) event (476 mm in 24 hours). In the unlikely event that rainfall is greater than

the PMP, or operational errors cause water levels to exceed the available (1m) freeboard, an emergency

spillway will be constructed in the eastern abutment of the TMF embankment in order to protect the integrity

of the facility in the event of emergency overflow. A decant pond will be located downstream of the spillway

to collect process water before it is pumped back to the Process Plant. The TMF embankments / dams have

been designed to store all storm events and annual rainfall sequences to a 1 in 100 year average recurrence

interval (Knight Piesold, 2015f ).

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Pit Wall Failure

Static and kinematic geotechnical analyses have been conducted in order to inform pit wall stability.

Kinematic analyses show that the maximum overall slope angle for the fresh and transition zone is

constrained by the bench and berm geometry, which is based on the requirement for these to minimise

kinematic instability and trap potential rock fall (Coffey, 2015).

If pit slumping and slope failure does occur, the environmental consequences will be physically constrained

by the pit walls.

Waste Rock Dump Failure

The WRD will be constructed from the bottom up so that the toe support is provided to the sections of WRD

located on steeper and higher ground.

The WRD will be compacted at the completion of each lift in order to maintain stability. Each of the

completed lifts of the WRD will be progressively rehabilitated with vegetation throughout the Operation

Phase. This will also help to retain stability.

Drought

Water from the Gambia River will only by pumped to the WRD during rainy season months. The pumping

schedule from the Gambia River should be contingent on river level and not solely the timing of the wet

season months. During significant drought conditions, abstraction rates from the Gambia should be reduced

if the downstream environment would be further affected by pumping.

Dust Storms

Minimising the extent of vegetation clearing, erosion control facilities, progressive rehabilitation, and road

watering (detailed in sections above) will minimise the impact from significant dust storms. Beyond this, the

primary management measures would be covered in Occupational Health and Safety Plans (refer to ESMMP)

to minimise impacts to Project personnel.


While the potential for impacts from accidental events and natural hazards cannot be eliminated, the Project

has been designed to avoid or minimise the probability and potentially significant consequences of such an

event. Management and mitigation measures are expected to minimise the associated attendant risks to an

acceptable level.

9.14 Climate and Greenhouse Gases


An understanding of climate change trends can provide guidance on predicting future meteorological

conditions in the Mako Gold Project region. The leading international body for climate change assessments is

the Intergovernmental Panel on Climate Change (IPCC), which was established by the United Nations

Environment Program (UNEP) and World Meteorological Organization (WMO) in 1988, to provide clear

scientific views on the current knowledge of climate change. Senegal has been identified as one of the top

three countries in the Sahel region at risk from the effects of climate change (World Bank, 2009).

The scientific community is of the consensus that climate change is caused by increased concentrations of

greenhouse gases in the atmosphere. The Intergovernmental Panel on Climate Change (IPCC), the United

Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol have been established

to address this issue. Greenhouse gases in this context include carbon dioxide (CO2), methane (CH4), nitrous

oxide (N2O), as well as perfluorocarbons (PFCs) and fluoride gases.

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FINAL 9-94

Climate Change is a global issue. Key considerations for Senegal are temperature and rainfall trends, which

are described below.

Mean annual temperatures in Senegal have increased by 0.9°C since 1975 (UNDP 2010);

The mean annual temperature is projected to increase by 1.1 to 3.1°C by the 2060s from current

temperatures, and 1.7 to 4.9°C by the 2090s based on various emissions scenarios;

The projected rate of warming is faster in the interior of Senegal than in the coastal regions;

Rainfall data from Kedougou show a general decrease of approximately -14% over the last century;

Rains have remained steady in Senegal over the past 20 years, but are 15% below the 1920-1969 mean;

Rainfall projections from different models do not agree on the precipitation changes in the region, but

predict general decreases for the wet season of up to -18% for the 21st century;

Heavy rainfall events during the wet season are predicted to increase despite the overall decrease in

annual precipitation; and

General increases in variability and extremes are predicted across the region.

The Republic of Senegal ratified the United Nations Framework Convention on Climate Change (UNFCCC) on

17th October 1994 and ratified the Kyoto Protocol on 20th July 2001. Obligations that come under the

ratifications include undertaking a source and sink greenhouse gas inventory, identifying greenhouse gas

mitigation options, formulating greenhouse gas mitigation strategies and a national implementation plan

that covers all sectors, including energy, industry and transport. Senegal completed its Initial National

Communication (INC) to the UNFCCC in 1997 and the Second National Communication (SNC) in 2010. As of

2015, the SNC report is the most recently reported data on Senegal’s greenhouse gas emissions inventory and

is based on 2000 levels.

Based on the SNC, total greenhouse gas emissions in Senegal in 2000 were estimated at 16,894 kilotonnes

CO2 equivalent. However, some 10,587 kilotonnes of CO2 equivalent is being sequestrated by the forestry

sector (UNFCCC, 2010). The largest emitting sector in Senegal is the energy sector, contributing to 49% of the

country’s total emissions. This is followed by the agriculture sector at 37%, waste at 12%, and 2% from

industrial processes.

The following greenhouse gas assessment for the Mako Gold Project is an initial assessment of the likely

magnitude of emissions from the Project only. The assessment has been based on the methods outlined in

the Greenhouse Gas Protocol: A Corporate Accounting and Report Standard (World Business Council for

Sustainable Development and World Resources Institute, 2004) and 2006 IPCC Guidelines for National

Greenhouse Gas Inventories.

As detailed data for the calculation of greenhouse gas emissions and energy usage was not available at this

stage of the Project, this is considered preliminary assessment and only the potential emissions during the

Operation Phase have been estimated. For the Construction Phase, only potential emissions related to

vegetation clearance are considered (other emission sources during Construction are not included due to

data limitation).

The Project is expected to produce greenhouse gas emissions from the following main sources.

Scope 1 (direct) emissions from:

» Fuel used for Power Station on-site (diesel Power Station);

» Diesel usage for mining activities;

» Supplies transportation to site; and

» Vegetation clearance.

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There is not expected to be Scope 2 (indirect) emissions from the consumption of electricity from the grid, as

all electricity will be provided from an on-site Power Station.

Scope 3 emissions are indirect GHG emissions which occur as a result of sources not owned or controlled by

MEC in relation to the Project, for example embodied emissions from material use in the Project, emissions

from equipment delivery to site, and travel emissions of employees to site. Scope 3 emissions are excluded in

this assessment due to data limitation.

The main greenhouse gases produced by the Project are likely to include:

Carbon dioxide (CO2);

Methane (CH4);

Nitrous oxide (N2O);

Sulphur hexafluoride (SF6); and

Hydrofluorocarbons (HFCs).

Industry best practice management will be implemented at the Project site to ensure that greenhouse gas

emissions are minimised through measures such as:

Measure overall greenhouse gas reduction progress and report results;

Promote technical innovation and creativity in low greenhouse gas emissions technologies while

enhancing energy and resource efficiency;

Ensure efficient use of renewable and non-renewable natural resources;

Develop appropriate adaptation strategies specific to each operation; and

Contribute to the sustainable development of local communities and societies in adapting to the

impacts of climate change.

All greenhouse gas emissions associated with the Mako Gold Project are expected to occur as a result of

Scope 1 (direct emissions) from the on-site Power Station, fossil fuel usage in mining activities, and supplies

transportation.

Power will be generated on-site by a dedicated diesel-fuelled project Power Station. The Project is expected

to generate 809,000 tCO2e at a minimum over the Project’s operational life of eight years, or approximately

102,000 tCO2e per annum. The overall emissions increase to approximately 831,000 tCO2e when vegetation

clearing is included.

Table 9-28 illustrates the overall minimum emissions of the Project.

Table 9-28 Initial estimate of the Project’s minimum overall emissions Activities Estimated tonnes of

CO2e per annum ^ Estimated tonnes of CO2e over

8-year operational life ^

Project Construction Phase

Vegetation clearing# – Scope 1

2,810 # 22,500 (other activities during construction is not included at this stage)

Project Operation Phase

Diesel Power Station– Scope 1 81,300 650,000

Diesel Usage for Mining Activities – Scope 1 18,600 149,000

Supplies Transportation to Site – Scope 1 1,250 9,990

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Activities Estimated tonnes of CO2e per annum ^

Estimated tonnes of CO2e over 8-year operational life ^

TOTAL Operation Phase Emissions using Diesel Power Station

102,000 809,000

OVERALL TOTAL Construction and Operation using Diesel Power Station (incl. vegetation clearing)

104,000 831,000

^ Numbers are rounded up to three significant figures.

# This represents the average yearly emissions for land clearing. Note that most likely the majority of emissions due to land clearing would occur

during Pre-Construction and Construction period.

** The emissions here do not consider the effect of revegetation and mine rehabilitation.

A breakdown of the estimated emissions from the Project (based on available data only) is provided in the

sections below.


Only emissions from vegetation clearance are considered for the Construction Phase. Other main emission

sources during Construction that could be included once data becomes available include fossil fuel usage for

construction activities, use of explosives, and transportation of materials to the Project site.

It is expected that approximately 240 ha of natural habitat (IFC, 2012) and 4 ha of modified habitat (IFC, 2012)

will be cleared prior to the construction of the main Project components, Main Access Road, haul road and

pipeline.

For the purpose of estimating the emissions due to vegetation clearing, it is assumed that the area to be

cleared is categorised as “Woodland and Scrub” based on the National Carbon Accounting System Technical

Report No. 17. The woodland and scrub category has the lowest biomass density of the three available

biomass categories, with a density of 51 t/ha. This is expected to be an over-estimate of biomass, however it

represents the closest applicable vegetation category for the emissions estimate.

Based on an estimated area of 240 ha, vegetation type of woodland and scrub, approximately 12,300 tonnes

of biomass would be cleared. Assuming 50% carbon content of the biomass, this translates to approximately

6,120 tonnes of total carbon. Thus assuming all the carbon is converted to carbon dioxide through natural

decomposition (or burning), this equates to approximately 22,500 tCO2e of emissions released during the

vegetation clearing phase.

At the end of the mine life, some of the emissions from vegetation clearing would be offset through native

revegetation and mine site rehabilitation (see Rehabilitation and Conceptual Mine Closure Plan – Volume

E). The assessment here considers the emissions without considering the effect of revegetation and mine

rehabilitation.

Operation

Three emission sources are considered for the Operation Phase, including: fuel usage for electricity

generation (diesel power station), fuel usage for mining activities, and transportation of supplies to site.

Power Station

The diesel Power Station has a maximum capacity at 16.5 MW and a typical continuous load at 9.8 MW.

A typical fuel consumption for a diesel generator at 1.8 MW is estimated at 0.33 L/kWh (Cummins 2660DQLB

Emissions Data Sheet, EDS-1009, 2010). Assuming 24 hours and 365 days operation per year and applying

typical diesel’s energy content of 38.6 GJ/kL (AGDE, 2014) and emission factor of 74,289 kgCO2e/TJ for

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stationary energy (IPCC, 2006), the yearly emissions are estimated at 81,300 tCO2e. Overall emissions during

operational life of 8 years are around 650,000 tCO2e.

Mining Activities

Diesel fuel usage data for mining activities from the Company are provided at 6,000 m3/year. It is assumed

that this amount covers all activities occurring at the mine site. Using the same typical diesel energy content

as above and an emission factor of 80,193 kgCO2e/TJ for a mobile emission source (IPCC, 2006), gives a yearly

emissions estimate of 18,600 tCO2e. Over the 11-year operational period, the total emissions become 205,000

tCO2e.

Supplies Transportation

Transportation of supplies to the Project Site from Dakar (650 km distance) are estimated at three trucks per

day. For an operational period of 365 days per year, this gives a total of 1,095 trucks per year (see Table 9-29).

As truck type data was not available at time of writing, for the purpose of conducting initial assessment, truck

type is assumed to be articulated truck carrying 33 tonnes of goods or less. It is also assumed that there

would be 100% load of supplies from Dakar to Mako and 0% load from Mako to Dakar. Note that this is likely

to result in an over-estimate of GHG emissions from supplies transportation. More accurate estimation should

be calculated once detailed supplies transportation data is available.

The initial emissions estimates were calculated using an emission factor for articulated trucks derived from a

report compiled by UK’s Department for Environment, Food, and Rural Affairs (DEFRA, 2011). DEFRA has

reviewed emissions for different modes of freight transport mechanisms, and developed ranges of emissions

for each mode (including different emission factors for trucks at 100% load and 0% load). This method was

applied due to the unavailability of fossil fuel estimates for the Project. Once the fossil fuel usage data for

supplies transportation becomes available, more accurate estimates will be able to be calculated.

Table 9-29 Initial estimation of greenhouse gas emissions for transportation of supplies

Route Distance

(Km)

Assumed

load of

supplies

No. of

trucks per

day

No. of

trucks per

year

Estimated

tonnes of CO2e

per annum ^

Estimated tonnes of

tCO2e per route over 8-

year operational life ^

Dakar to Mako 650 100% load 3 1,095 748 5,990

Mako to Dakar

(return trip) 650 0% load 3 1,095 501 4,010

TOTAL 1,250 9,990

^ Numbers are rounded up to three significant figures.

Other Emission Sources

There are other emission sources during the Operation Phase that are not considered in this assessment due

to data limitation, such as waste disposal, other fuel usage (i.e. remote generators) and wastewater treatment.

These emission sources are likely to be minor in comparison to the operation’s emissions detailed above.


During closure, there will be rehabilitation and revegetation activities as described in Rehabilitation and Conceptual Mine Closure Plan (Volume E). No detailed data on fossil fuel usage during this period is

available at this stage.

The planned revegetation activities indicate that some of the potential emissions due to vegetation clearance

mentioned above would eventually be offset. This should be analysed further once comprehensive data on

planned revegetation activities becomes available.

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Minimisation

Prior to construction, an Environmental and Social Management and Monitoring Plan (ESMMP) will be

completed. This plan will outline the necessary strategies, procedures, and reporting requirements in fulfilling

their statutory requirements and voluntary commitments, including greenhouse gas emissions commitments.

The ESMMP includes the following measures:

Maximise efficiency of energy use (type of fuel, lighting, water etc.)

Minimise land clearance to reduce carbon loss;

Maximise absorption/offset of greenhouse gases through revegetation of land during and after mining

(as per the Rehabilitation and Conceptual Mine Closure Plan, Volume E); and

Use best available technology to minimise greenhouse gas emissions at mine site and processing

facility.

During Construction, the Company should implement the measures outlined in the ESMMP’s Greenhouse

Gas Management Plan developed for the Project. Such measures will include:

Follow international industry practices for minimising Project related greenhouse gas emissions,

particularly for major emission sources (on-site Power Station);

Apply appropriate greenhouse gas management measures to all Project-related transport activities;

Integrate energy efficiency principles in building or facility design;

Ensure contractors comply with relevant energy conservation measures outlined in the ESMMP;

Conduct awareness training on energy conservation and greenhouse gas reduction for Project

employees and workforce; and

Establish energy conservation targets for the Project for measuring improvement in greenhouse

intensity of mining operation in accordance with good international industry practices.

During operation, the control procedures for reducing energy and greenhouse gas emissions shown in Table

9-30 should be implemented.

Table 9-30 Greenhouse gas emissions / energy source and control procedures

Source Control Procedures

Heavy equipment

and vehicles

Improve fuel efficiency of all Project vehicles by recording fuel usage and undertaking regular

maintenance;

Maximise the benefits of gravity in movement of material and minimise the need for uphill

movements;

Minimise multiple handling requirements, through optimisation of ore and waste handling processes;

Minimise idling time and distances travelled in vehicles and movement of equipment through active

scheduling;

Where possible, select most fuel efficient vehicles and equipment viable for use on site;

Eliminate unnecessary use and fuel consumption, through the establishment of a central control

system for equipment dispatch;

Regular maintenance of diesel power units;

Optimise operating efficiency of Power Station; and

Consider a visitor area for drivers, to prevent long-time idling of trucks/vehicles

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Source Control Procedures

Energy Usage Consider the use of solar power and biofuels to substitute or augment fossil fuel usage for electricity

generation;

Use of “high-efficiency” motors in equipment that is continuously operated;

Capacitor bank to improve the power factor;

Optimising dewatering and pumping systems to minimise energy use for water management;

Reducing pumping requirements by situating the main mine header tank uphill;

Design and implementation of dust suppression systems that can be switched off when watering is

not required; and

Use efficient and shielded lighting that requires less energy


During Decommissioning/closure, MEC will continue to implement the measures outlined in the

Rehabilitation and Conceptual Mine Closure Plan (Volume E) (to be developed for the Project). Key

measures to assist in minimising greenhouse gas emissions during rehabilitation and closure activities

include:

Progressively rehabilitating cleared land during operation to ensure that land is revegetated as soon as

possible after mining and waste disposal operation are completed;

Mulch and chip cleared vegetation rather than burn and re-use in rehabilitation;

Consider converting cleared vegetation to biochar and use in rehabilitation; and

Revegetate with native plants such as fast growing bamboo.


It is expected that the residual impact of the Project would be Minor provided that the Project follows the

above avoidance, mitigation, and management measures (including those outlined in the ESMMP) and

Rehabilitation and Conceptual Mine Closure Plan, Volume E). By following the above, monitoring of

greenhouse gas emissions are likely to be regularly performed, emissions reduction targets regularly set, and

reduction measures implemented and continually improved to minimise any residual impact that may arise.

The key expected residual impacts related to climate and greenhouse gases under normal operating





climate and greenhouse gas emissions for each Project phase


Significance



Climate and Greenhouse Gases – fuel and energy use

MODERATE

Maximise efficiency of energy use (type of

fuel, lighting, water etc.)

Follow international industry practices for

minimising Project related greenhouse gas

emissions, particularly for major emission

MINOR

Greenhouse gas emissions will occur due to mining activities

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Significance


sources (on-site Power Station)

Apply appropriate greenhouse gas

management measures to all Project-related

transport activities.

Integrate energy efficiency principles in

building or facility design.

Ensure contractors comply with relevant

measures outlined in the ESMMP to be

prepared for the Mako Project.

Establish energy conservation targets for the

Project for measuring improvement in

greenhouse intensity of mining operation in

accordance with good international industry

practices.

Climate and Greenhouse Gases – Vegetation Clearing

MODERATE

Minimise land clearance to reduce carbon

loss.

Mulch and chip cleared vegetation rather than

burn and re-use in rehabilitation.

Maximise absorption/offset of greenhouse

gases through revegetation of land during and

after mining (as per the Rehabilitation and

Conceptual Mine Closure Plan, Volume E).

MINOR

Reduction in air pollution due to smoke

Additional mulch to ensure revegetation success

Removal of vegetation during mining

Operation

Climate and Greenhouse Gases - Heavy equipment and vehicles

MODERATE

Where possible, select most fuel efficient

vehicles and equipment viable for use on site

Maximise the benefits of gravity in movement

of material and minimise the need for uphill

movements.

Minimise multiple handling requirements,

through optimisation of ore and waste

handling processes.

MINOR

Greenhouse gases will be generated through fuel use

Cost of fuel can be minimised through materials handling efficiency

Climate and Greenhouse Gases - Energy Usage

MODERATE

Use best available technology to minimise

greenhouse gas emissions at mine site and

processing facility.

Consider use of renewable energy such as

wind, solar and biofuels to substitute or

augment fossil fuel usage for electricity

generation.

MINOR

Energy use will contribute to greenhouse gas production


MODERATE

Progressively rehabilitating cleared land

during operation to ensure that land is

revegetated as soon as possible after mining

and waste disposal operations are completed.

MINOR

Native vegetation will be removed to undertake mining

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Significance




MINOR


Revegetate with native plants such as fast

growing bamboo.

NEGLIGIBLE

Fast re-vegetation restores carbon sink and improves water quality outcomes

9.15 Visual Amenity


Assessment of the potential Project related impacts to the baseline visual amenity within and in proximity to

the PDA during construction, operation and decommissioning / closure involved:

Photographic surveys of potential impact sites and sensitive receptors during wet and dry seasons

(2014) to determine line-of-site from Project components; and

Computer simulations of predicted visual impacts of the Project from sensitive receptor locations

(viewshed analysis).

The viewshed analysis was conducted using Geographic Information System (GIS) software. A 3-dimensional

terrain model of the area was produced with the major features of the proposed Project Footprint overlaid on

the surface terrain to predict the approximate visibility of Project components for potential receptor sites (e.g.

local communities and PNNK).

The viewshed analysis considered line-of-site to primary Project components (e.g. Mine Pit; WRD; Process

Plant and ROM Pad; TMF; WSD; Power Station, Main Access Road and night-lighting for components) while the

overall impact assessment considered additional elements, including upgrade of the existing Mako-

Tambanoumouya Road (paralleling the Gambia River), additional vehicles in the Project region, skyglow from

night-works, etc.

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Figure 9-18 3D Terrain model with Project components and potentially sensitive receptors

The primary and ancillary components of the Mako Gold Project are located at a moderate distance from the

nearest potentially sensitive receptors (i.e. villages and PNNK). Many of the components (e.g. the TMF, the

majority of the WRD and Mine Pit) are located within Badalla Valley, where topographic relief will shield the

areas from direct line of site. The impacts to visual amenity are expected to be low for most receptors, though

may be Moderate for villages with direct line of site to the WRD and Process Plant / Power Station.

The viewshed analysis (Figure 9-14), identifies areas that are visible from the location of the proposed Project

component. Some of the components will become progressively less visible throughout operation (i.e. the

Mine Pit), while the remainder will be rehabilitated and revegetated during Project operation (WRD) and

following Project decommissioning (with the exception of the main access road and workforce

accommodation).


Due to the topography of the PDA (i.e. topographic relief and shielding), visual amenity for various receptors

will vary during construction, with potential for direct line-of-site to one or more of the following for the

communities / PNNK receptors identified in Figure 9.13:

Badalla Valley vegetation clearance (e.g. Mine Pit, WRD) and construction (TMF);

Process Plant, ROM Pad, and Power Station vegetation clearance area and facilities’ construction;

WSD embankment and Main Access road construction;

Mako to Tambanoumouya road upgrade (paralleling the Gambia River); and

Increased Project-related traffic, including associated dust emissions during the dry season (particularly

for Access Road upgrade and Main Access Road Construction near National Route 7.

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Visual modification during construction and the potential severity of impacts to visual amenity for local

receptors are provided in Table 9-32. Potential impacts were determined via GIS viewshed analysis developed

from photographs (refer to Figure 9-14) and simulated viewshed analyses (refer to Table 9-32). The potential

impact of visual modification is expected to be less during the wet season due to the increased presence of

vegetation and the screening that it provides.

Table 9-32 Pre-Construction and Construction Phase visual impact assessment

Site Name Construction / Visual Modification Potential Impact

Tambanoumouya WRD and Pit vegetation clearance MODERATE

Kerekonko WRD and Pit vegetation clearance MODERATE

PNNK (eastern limit) WRD and Pit vegetation clearance LOW

Linguekoto Construction Access Road Upgrade, Traffic, Dust LOW

Dalakoy Process Plant, Power Station and WSD Construction (potentially) LOW

Wassadou Process Plant and Power Station Construction LOW

Mako Construction Access Road Upgrade, Traffic and Dust LOW

Niemenike/National Route 7 Main Access Road Construction, Traffic and Dust LOW

Badian (Maragoukoto) Mako Camp NEGLIGIBLE

Sekoto NA NEGLIGIBLE

Tomboronkoto NA NEGLIGIBLE

Operation

Visual amenity during operation will also vary for receptors due to local topographic features and distance

from operation. The context of visual amenity impact will change for respective receptors (compared to

Construction Phase) as night-time operation (and associated lighting) will be introduced, whilst road

construction, vegetative clearance, and use of the Temporary Construction Access Road will cease or be

significantly reduced. The primary potential impacts to visual amenity are provided below, with an

assessment of these impacts for applicable receptors provided in Table 9-33, visual viewshed analysis ( Figure

9-19) and viewshed simulation for the select villages is provided in Table 9-35.

Night-lighting – It is anticipated that the Project will be in operation for 24 hours per day, with the

main components illuminated for safety. The lack of electricity in the area is such that the PDA is

currently isolated from the effects of night lighting. Direct line-of-site to Project associated night-

lighting is likely for residents of Tambanoumouya, Kerekonko, and potentially Dalakoy as well as for

southern portions of the PNNK (e.g. PNNK 1 in Figure 9-18).

Skyglow - Though a lesser impact than direct view of night-lighting, indirect light may be visible for

the majority of villages within proximity of the PDA. Skyglow (a brightening of the night sky above the

Project) varies with changes in humidity, cloud cover, dust concentration and light output.

Badalla Valley Project Components – Though the Mine Pit footprint is located on the crest of the

ridge line and hence is currently visible by a number of the surrounding villages, the majority of the

facility will not be within line-of-site (subsurface). The WRD and TMF will become progressively more

visible throughout operation. The GIS viewshed analyses predict that the most affected sensitive

receptors are likely to be Kerekonko, Tambanoumouya and Dalakoy. These villages are within a few km

of the WRD and have relatively unimpeded views of the Badalla Valley.

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Process Plant, Power Station and ROM Pad – As these facilities straddle the ridgeline of the Badalla

Valley, they will be visible to more receptors than for Badalla Valley Project facilities. Lighting (if

applicable) would provide direct and indirect impacts after nightfall. These facilities will be visible for

Tambanoumouya, Kerekonko, Dalakoy, and Wassadou.

WSD and Main Access Road – The Main Access Road and WSD road, cutting across the foot of the hill

may, will be constructed within a relatively undisturbed setting. These components will be visually

prominent until a moderate level of vegetation cover is established at their margins. Vegetative

screening will incrementally increase as forest tree cover re-establishes on the foot-slopes of the road

cutting. Sections of the Main Access Road will be visible in Linguekoto, Dalakoy and Wassadou. These

components are not expected to impact visual amenity to a great extent.

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Figure 9-19 GIS Viewshed Analysis for Project Components

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Table 9-33 Operation Phase Visual Impact Assessment

Site Name Distance

From Pit

Visual Modification Impact

Assessment

Tambanoumouya 3.0 km WRD, Lighting and Skyglow MODERATE

Kerekonko 4.0 km WRD, Process Plant, Lighting and Skyglow MODERATE

PNNK (southern portion) 4.3 km WRD, Lighting and Skyglow MODERATE

Linguekoto 4.5 km Mako Camp and Skyglow LOW

Dalakoy 4.7 km Process Plant and Skyglow LOW

Wassadou 5.2 km Process Plant and Skyglow LOW

Niemenike/National Route 7 9.0 km Access Road. Traffic LOW

Badian (Maragoukoto) 7.4 km Skyglow NEGLIGIBLE

Mako 8.6 km Skyglow NEGLIGIBLE

Sekoto 14.4 km Skyglow NEGLIGIBLE

Tomboronkoto 17 km Skyglow NEGLIGIBLE

The following simulated views of Project components are displayed from a vantage point of 100 m above

ground level in respective village locations (the images increasingly blur when simulating closer to the

ground). The view of Project facilities presented in these simulations is therefore less impeded by

topographic relief than will be the case from a ground-level perspective. Impacts to visual amenity are

therefore expected to be less than that represented in Table 9-34.

Table 9-34 Simulated Views of Project Components from 100 m Elevation above Receptors

Receptor Simulated View (from 100m above receptor)

Tambanoumouya

(viewing north-

west)

Tambanoumouya

(viewing east)

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Kerekonko

(viewing north)

Dalakoy

(viewing north)

Linguekoto

(viewing north-

west)

Linguekoto

(viewing north-

east)

Wassadou

(viewing north-

east)

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Badian (viewing

west)

Mako (viewing

southwest)


Impacts to visual amenity associated with decommissioning / closure are expected to be limited to dust

generation associated with landform rehabilitation (topsoil application and re-contouring) and equipment

operation necessary for decommissioning of facilities. Facilities to be rehabilitated are > 3 km from the

nearest village, therefore visible impacts are expected to be Minor to Negligible (refer to Table 9-35).

Progressive rehabilitation and revegetation during operation (e.g. WRD) and full-scale rehabilitation and

revegetation of the remainder of the temporarily disturbed areas (refer to Section 9.1) will incrementally

improve the visual amenity of the Project Footprint. The view from the PNNK will gradually improve as the

WRD is rehabilitated and the post-closure impact is expected to be Negligible. Though some landforms will

differ from their pre-Project morphology, provision of natural ecosystems during the five-year closure period

is a primary objective of the Rehabilitation and Conceptual Mine Closure Plan (Volume E).

Table 9-35 Post-Closure Visual Impact Assessment

Site Name Distance

From Pit


Assessment

Tambanoumouya 3.0 km Upper Pit rim LOW

Kerekonko 4.0 km Upper Pit rim LOW

PNNK (southern portion) 4.3 km Rehabilitated WRD NEGLIGIBLE

Linguekoto 4.5 km NA NEGLIGIBLE

Dalakoy 4.7 km NA NEGLIGIBLE

Wassadou 5.2 km NA NEGLIGIBLE

Badian (Maragoukoto) 7.4 km NA NEGLIGIBLE

Mako 8.6 km NA NEGLIGIBLE

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Site Name Distance

From Pit


Assessment

Niemenike/National Route 7 9.0 km Rehabilitated WRD NEGLIGIBLE

Sekoto 14.4 km NA NEGLIGIBLE

Tomboronkoto 17 km NA NEGLIGIBLE


Avoidance

The following will be adopted by the Company to reduce Project related impacts to visual amenity during

operation:

Lighting design will incorporate the minimum wattage required for a safe working environment;

Lights will be pointed downward and toward operational areas, minimising light egress.

Shielded lighting will be utilised to minimise night-time light egress from operational areas and

skyglow.

Low-visibility fencing will be utilised to the extent practicable (such as wire mesh, rather than palisade

or solid fence structures);

Non-reflective surfaces for incorporated into roofing, fencing and building design.

Signage will be restricted to the minimum required with due consideration to safety; and

Visual barriers will be evaluated for implementation, such as tree or bamboo planting (e.g. around Mine

Pit perimeter that does not require access) to reduce potential impacts on visual amenity.

Minimisation

The Company will adopt the following measures to minimise impacts to visual amenity of the PDA (and

surrounds) during construction:

Vegetation clearance will be restricted to the minimum extent practicable for Project construction;

Cleared areas around facilities will be progressively rehabilitated and revegetated to the extent

practicable as soon as respective areas are no longer required for construction / operation;

Dust suppression (water spray) will be actively implemented on the unsealed road network during the

dry season (refer to Section 9.8 and Chapter 11), particularly near sensitive receptors;

Project structures will be painted in muted colours in keeping with the local area and vegetation;

Construction sites will be well maintained and kept tidy;

Physical barriers such as earth/rock banks or vegetation will be considered for concealing Project

components to the extent feasible;

Long-term soil stockpiles will be planted / seeded with grasses or similarly fast growing vegetation;

Where relevant, visual amenity management and mitigation measures will be incorporated into the

Construction and Environmental Management Plan(CEMP); and

A Grievance Mechanism will be established to provide a means for responding to stakeholder

concerns.


As per the Rehabilitation and Conceptual Mine Closure Plan (Volume E), disturbed areas will be

progressively rehabilitated throughout Project operation. For example, the WRD will be revegetated from the

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FINAL 9-110

bottom upward throughout operation and is expected to be revegetated in advance of Project closure (as

waste disposal will cease after the sixth year of operation).

Temporarily disturbed areas (e.g. WRD, TMF, Process Plant and ROM Pad, Power Station, WSD, etc.) will be

rehabilitated and revegetated during Project closure to provide self-sustaining natural ecosystems similar to

the surrounding environment. After decommissioning / contouring landforms; Tree savannah, Wooded

savannah, or Shrub savannah vegetative communities will be established (refer to Rehabilitation and Conceptual Mine Closure Plan, Volume E). Though the shape of some landforms will change (e.g. WRD and

TMF), the habitat quality (and visual amenity) will increasingly improve following Project decommissioning

until these facilities blend with their surroundings. Given the high rainfall and tropical climate of the region,

regeneration of the savannah is expected to be fairly rapid, though tree growth may require some time to

achieve pre-Project character.

The Mine Pit, workforce accommodation facilities and the majority of road infrastructure will remain following

Project closure. As vegetation establishes around remaining facilities, the visual amenity will incrementally

improve.


During construction, there may be moderate impacts on visual amenity for the villages of Tambanoumouya

and Kerekonko and eastern limit of PNNK, with direct line-of-site to some of the Badalla Valley vegetation

clearance and Process Plant construction area. There may also be a moderate impact on the village of

Linguekoto, with exposure to road upgrade work and increased vehicular travel (and dust) associated with

upgrade of the existing Access Road from Mako to Tambanoumoya, paralleling the Gambia River. Given the

distance and topographic shielding for much of the PDA, management measures are expected to reduce

impacts to visual amenity to a Minor or Negligible level of impact for the remainder of the receptors during

construction.

During operation, there may be Moderate impacts on the visual amenity for Tambanoumouya and Kerekonko

as well as the eastern limit of the PNNK. The WRD will become progressively more visible and night-lighting

may be directly visible from the Badalla Valley and the ridgeline separating Badalla / Wayako Valleys. Given

the topographic shielding, distance to the PDA, and management / mitigation measures, Minor to Negligible

level impacts to visual amenity are anticipated for the remainder of receptors in proximity to the PDA (i.e.

within 20 km) during operation, with the primary impact expected to be skyglow. Measures to reduce egress

of light from night-time work areas during operation will significantly reduce this potential impact.

Post-closure, rehabilitation and revegetation activities will progressively return the visual amenity of

temporarily disturbed areas to pre-Project conditions (refer to Figure 9-20). The Mine Pit (a permanently

impacted facility) will likely not be visible for local communities (sub-surface with vegetative buffer for the Pit

rim). Residual impacts to visual amenity will include the existence of the Main Access Road and workforce

accommodation facilities, which are considered low to Negligible impacts.

The key expected residual impacts related to visual amenity under normal operating conditions, and their



accordingly.

Table 9-36 Summary of key expected pre-mitigation impacts, mitigation measures and residual impacts on visual

amenity for each Project phase

Receptor / Value Expected Pre-Mitigation Impact Significance


Key Expected Residual Impacts and



Visual Amenity MODERATE Vegetation clearance

restricted to the minimum extent practicable for Project

MINOR

Visual impacts are Minor in specific view

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construction

Cleared areas around facilities progressively rehabilitated and revegetated to the extent practicable as soon as respective areas are no longer required for construction / operation

Project structures painted in muted colours in keeping with the local area and vegetation

Construction sites well maintained and kept tidy

Physical barriers such as earth/rock banks or vegetation considered for concealing Project components to the extent feasible

Where relevant, visual amenity management and mitigation measures incorporated into the CEMP


fields

Operation

Visual Amenity MODERATE

Lighting design will incorporate the minimum wattage required for a safe working environment

Lights pointed downward and toward operational areas, minimising light egress

Shielded lighting utilised to minimise night-time light egress from operational areas and skyglow

Low-visibility fencing will be utilised to the extent practicable (such as wire mesh, rather than palisade or solid fence structures)

Visual barriers evaluated for implementation, such as tree or bamboo planting (e.g. around Mine Pit perimeter that does not require access) to reduce potential impacts on visual amenity

Routine checks for

MINOR

Progressive habitat restoration will reduce overall impacts in the Operation Phase

Use of screening vegetation to reduce visibility of large mine structures

Large structures will be visible from specific view fields

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compliance


Visual Amenity MODERATE


Use of selected native and endemic vegetation for revegetation of site areas

Use of fast growing vegetation to reduce visual impacts of closure as quickly as possible


MINOR

Habitat restoration will reduce overall visual impacts Post-Closure

Some areas of permanent vegetation loss will remain (e.g. pit and TMF)

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Figure 9-20 Mako Gold Project Post-Closure

Management Measures Chapter 9 | Biological Impacts and

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