APPENDIX G: AIR QUALITY IMPACT ASSESSMENT

Webequie Supply Road Project
Webequie First Nation
August 19, 2024
AtkinsRéalis Ref: 661910

APPENDIX G: AIR QUALITY IMPACT ASSESSMENT

AtkinsRéalis – DRAFT

Notice to Reader
This report has been prepared and the work referred to in this report has been undertaken by AtkinsRéalis Canada Inc., for the exclusive use of Webequie First Nation, who has been party to the development of the scope of work and understands its limitations. The methodology, findings, conclusions and recommendations in this report are based solely upon the scope of work and subject to the time and budgetary considerations described in the proposal and/or contract pursuant to which this report was issued. Any use, reliance on, or decision made by a third party based on this report is the sole responsibility of such third party. AtkinsRéalis accepts no liability or responsibility for any damages that may be suffered or incurred by any third party as a result of the use of, reliance on, or any decision made based on this report.
The findings, conclusions and recommendations in this report (i) have been developed in a manner consistent with the level of skill normally exercised by professionals currently practicing under similar conditions in the area, and (ii) reflect AtkinsRéalis, best judgment based on information available at the time of preparation of this report. No other warranties, either expressed or implied, are made with respect to the professional services provided to Webequie First Nation or the findings, conclusions and recommendations contained in this report. The findings and conclusions contained in this report are valid only as of the date of this report and may be based, in part, upon information provided by others. If any of the information is inaccurate, new information is discovered or project parameters change, modifications to this report may be necessary.
This report must be read as a whole, as sections taken out of context may be misleading. If discrepancies occur between the preliminary (draft) and final version of this report, it is the final version that takes precedence. Nothing in this report is intended to constitute or provide a legal opinion.
The contents of this report are confidential and proprietary. Other than by the Webequie First Nation, copying or distribution of this report or use of or reliance on the information contained herein, in whole or in part, is not permitted without the express written permission of the Webequie First Nation and AtkinsRéalis.

Signature Page

Prepared by:
Simon Piché, Ph.D., P.Eng.
Project Manager, Air Quality and Climate Change
Acoustics, Air and Climate Change
Engineering Services – Canada

Reviewed by: Chris Bestfather, M.A.Sc., P.Eng.
Environmental Engineer
Environment
Engineering Services – Canada
Wanda Batista de Amorim, D.E.S.S., M.Sc.
Team Lead – Air quality
Environment
Engineering Services – Canada

Project Team
AtkinsRéalis Canada Inc.

Simon Piché Title
Chris Bestfather Title
Wanda Batista de Amorim Title

Contents

1. Introduction 9
   1.1 Project Overview 9
   1.2 Valued Component and Indicators 12
   1.3 Spatial and Temporal Boundaries 13
   1.3.1 Spatial Boundaries 13
   1.3.2 Temporary Boundaries 13
   1.4 Identification of Project Interactions with Air Quality 16
   1.5 Scope of the Air Quality Assessment 17
2. Modelling Methodology 19
   2.1 Air Dispersion Model 19
   2.2 Meteorological Dataset 21
   2.3 Modelling Domain 23
   2.4 Relevant Air Quality Criteria and Standards 24
   2.5 Summary of Existing Conditions 26
   2.6 Nitrogen dioxide: NO Conversion into NO2 30
   2.7 Dry Deposition Parameters on Dust Emissions 30
   2.8 Averaging Conversion Factor 30
3. Construction Phase 31
   3.1 Modelled Emission Sources 32
   3.2 Modelling Approach for Assessment 35
   3.3 Emission Rate Calculations 38
   3.3.1 Mobile and Stationary Equipment 38
   3.3.2 Trucking (road engines) 41
   3.3.3 Vehicular Dust Emissions 42
   3.3.4 Aggregate Crushing Plant 43
   3.3.5 Aggregate Loading and Unloading 44
   3.3.6 Operation of Dozers and Graders 45
   3.3.7 Blasting 46
   3.4 Emission Parameters Summary 47
   3.5 Mitigation Measures 48
   3.6 Air Dispersion Modeling Results 49
   3.6.1 Common Air Contaminants 55
   3.6.2 Toxic Contaminants 56
   3.6.3 Dust Deposition 56

3.6.4 Eastern Section of the WSR 56
3.6.5 Ground Level Ozone 57

4. Operation Phase 69
   4.1 Air Dispersion Modelling Approach 70
   4.2 Emission Rate Calculations 70
   4.2.1 Vehicular Traffic (road engines) 70
   4.2.2 Vehicular Traffic Dust Emissions 71
   4.2.3 Grading Dust Emissions 72
   4.3 Emission Parameters Summary 73
   4.4 Mitigation Measures 73
   4.5 Air Dispersion Modeling Results 74
   4.5.1 Common Air Contaminants 77
   4.5.2 Toxic Contaminants 78
   4.5.3 Dust Deposition 78
   4.5.4 Eastern Section of WSR 78
   4.5.5 Ground Level Ozone 79
5. Uncertainty Analysis 85
   5.1 Project Data 85
   5.2 Emissions Estimations 85
   5.3 Emissions Scenarios 86
   5.4 Dispersion Model 86
   5.5 Meteorological Dataset 87
   5.6 Background Concentrations 87
6. Description of Potential Effects and Interactions 88
   6.1 Construction Phase 89
   6.1.1 Potential Impacts on Ambient Air 91
   6.2 Operation Phase 92
   6.2.1 Potential Impacts on Ambient Air 92
7. Mitigations Measures and Net Effects 94
   7.1 Construction Phase 94
   7.2 Operation Phase 97
8. Concluding Remarks 99
9. References 100

Tables
Table 1-1: Air Quality VC – Indicators and Rationale 12
Table 1-2: Project Interactions with Air Quality VC 16
Table 2-1: Options Used in AERMOD 20
Table 2-2: Ambient Air Quality Criteria and Standards for Studied Contaminants 25
Table 2-3: Summary of Background Concentrations for Studied Contaminants 27
Table 3-1: Preliminary WSR Construction Planning 33
Table 3-2: Overview of Emission Sources Considered in the Construction Phase Model 36
Table 3-3: Emission Factors Obtained for CAT 329 Excavator 39
Table 3-4: Emission Rate Derivation Approach for Each Source and Average Period 40
Table 3-5: Trucking Scenario Considered in the Model 41
Table 3-6: Emission Factors for Trucks Exhaust Gases 42
Table 3-7: Applied Road Dust Emissions Control Factor – Construction Phase 43
Table 3-8: Input Data for Dust Emissions from Aggregate Crushing 44
Table 3-9: Input Data for Dust Emissions from Aggregate Loading and Unloading 44
Table 3-10: Emission Rates Weighting per Averaging Period for Dozers and Graders 46
Table 3-11: Input Rates Weighting per Averaging Period for Blasts 46
Table 3-12: Summary of Exhaust Gas Emission Sources for the Construction Phase 47
Table 3-13: Summary of Fugitive Dust Emission Sources for the Construction Phase 48
Table 3-14: Dry Depletion Parameters Applied for Dustfall and TSP Concentration Simulations 48
Table 3-15: Maximum Concentrations for CACs Calculated in Air During the Construction Phase
(without mitigation measures) 50
Table 3-16: Maximum Concentrations for Other Contaminants Calculated in Air During the
Construction Phase (without mitigation measures) 51
Table 3-17: Maximum Concentrations for Other Contaminants Calculated in Air During the
Construction Phase (with mitigation measures in place) 52
Table 3-18: Maximum Concentration for Contaminants Calculated in Air in Areas of Interest During the Construction Phase (with mitigation measures) 53
Table 4-1: Vehicular Traffic Scenario Considered in the Model 70
Table 4-2: Emission Factors for Vehicles Exhaust Gases 71
Table 4-3: Applied Road Dust Emissions Control Factor – Operation Phase 72
Table 4-4: Emission Rates Weighting per Averaging Period for Graders during Operation Phase 72
Table 4-5: Summary of Exhaust Gas Emission Sources for the Operation Phase 73
Table 4-6: Summary of Fugitive Dust Emission Sources for the Operation Phase 73
Table 4-7: Dry Depletion Parameters Applied for Dustfall and TSP Concentration Simulations 73
Table 4-8: Maximum Concentrations for CACs Calculated in Air During the Operation Phase
(without dust control) 74
Table 4-9: Maximum Concentrations for Other Contaminants Calculated in Air During the Operation Phase (without dust control) 75
Table 4-10: Maximum Concentrations of Certain Contaminants Calculated in Air During the Operation Phase (with dust control) 76
Table 4-11: Maximum Concentration for Contaminants Calculated in Air in Areas of Interest During the
Operation Phase (with dust control) 76
Table 6-1: Overview of Activities and Emission Sources during the First Year of Construction 90
Table 7-1: Air Dispersion Modelling Results for the Construction Phase 95

Tables (Cont’d)
Table 7-2: Air Dispersion Modelling Results for the Operation Phase 97
Table 7-3: Potential Particulate Emission Reduction with Asphalt or Chip Seal Pavement 98
Figures
Figure 1.1: Project Location 11
Figure 1.2: Air Dispersion Modelling Domain 14
Figure 1.3: Air Dispersion Modelling Domain (close-up near Webequie) 15
Figure 2.1: Annual Wind Rose 1996-2000 at International Falls Station Used in the Model 21
Figure 2.2: Seasonal Wind Rose 1996-2000 at International Falls Station 22
Figure 2.3: Annual Wind Roses at Meteorological Stations Closer to Site 23
Figure 2.4: Relation between mean TSP concentrations measured in air and mean dust deposition measurements carried out at 12 stations in Quebec City from 1979 to 1982 29
Figure 3.1: Location of Emission Sources for the Construction Phase 37
Figure 3.2: Maximum total daily TSP concentrations (g/m3) calculated in air during the construction phase 58
Figure 3.3: Maximum total daily PM10 concentrations (g/m3) calculated in air during the construction phase 59
Figure 3.4: Total daily PM2.5 concentrations (g/m3) calculated in air during the construction phase for comparison with the AAQC/CAAQS 60
Figure 3.5: Maximum total hourly NO2 concentrations (g/m3) calculated in air during the construction phase 61
Figure 3.6: Total hourly NO2 concentrations (g/m3) calculated in air during the construction phase for comparison with the CAAQS 62
Figure 3.7: Maximum total daily NO2 concentrations (g/m3) calculated in air during the construction phase 63
Figure 3.8: Maximum total hourly acrolein concentrations (g/m3) calculated in air during the
construction phase 64
Figure 3.9: Maximum total daily acrolein concentrations (g/m3) calculated in air during the
construction phase 65
Figure 3.10: Maximum total daily benzene concentrations (g/m3) calculated in air during the
construction phase 66
Figure 3.11: Maximum total propionaldehyde concentrations (g/m3) over 10 minutes calculated in air during
the construction phase 67
Figure 3.12: Maximum total dustfall over 30 days (g/m2/30 days) calculated on ground during the
construction phase 68
Figure 4.1: Maximum total daily TSP concentrations (g/m3) calculated in air associated with traffic and maintenance on the gravel-based road with dust mitigation measures 80
Figure 4.2: Maximum total daily PM10 concentrations (g/m3) calculated in air associated with traffic and
maintenance on the gravel-based road with dust mitigation measures 81
Figure 4.3: Total daily PM2.5 concentrations (g/m3) calculated in air associated with traffic and maintenance
on the gravel-based road with dust mitigation measures for comparison with the AAQC/CAAQS 82
Figure 4.4: Maximum total daily NO2 concentrations (g/m3) calculated in air associated with road traffic 83
Figure 4.5: Maximum total dustfall over 30 days (g/m2/30 days) calculated on ground associated with
traffic and maintenance on the gravel-based road with dust mitigation measures 84
Appendices
A: Calculation Note
B: Modelling Results for Sensitive Receptors

1 Introduction
Webequie First Nation is completing an Environmental Assessment (EA) under Ontario’s Environmental Assessment Act (EAA) and Impact Assessment (IA) under Canada’s Impact Assessment Act (IAA) for the proposed Webequie Supply Road (“the Project”, WSR). The proposed Project is a new all-season road of approximately 107 kilometres (km) in length, connecting Webequie First Nation and its airport to existing mineral exploration activities and proposed future mining development in the McFaulds Lake area. As part of both the provincial and federal assessments, the proponent (Webequie First Nation) must outline and discuss how the Project will impact the atmospheric environment during each phase of the Project. More specifically, this assessment is carried out to comply with the requirements from the Impact Assessment Agency of Canada (IAAC) in the Tailored Impact Statement Guidelines for the WSR (TISG Section 14.1 – Changes to the atmospheric, acoustic, and visual environment).
This report was prepared pursuant to the Climate Change and Air Quality Study Plan prepared by AtkinsRéalis (previously SNC-Lavalin) and submitted to the IAAC and the Ontario Ministry of the Environment, Conservation and Parks (MECP) in June 2020 for review and validation that it meets the federal requirements in the TISG and approved Terms of Reference for the provincial EA. The results of this air quality impact assessment will be documented and summarized in the Environmental Assessment Report/Impact Statement (EAR/IS) for the Project and is intended to meet the requirements of both the federal TISG and the provincially approved Terms of Reference.

1.1 Project Overview
The proposed WSR is a new two-lane all-season road within a cleared right-of-way (ROW) of approximately 35 metres
(m) in width and approximately 107 km in length. The preliminary recommended preferred route for the road consists of a northwest-southeast segment running 51 km from the Webequie First Nation Reserve to a 56 km segment running east-west before terminating near the McFaulds Lake within the mineralized deposit area known as the Ring of Fire. A total of 17 km of the WSR is within the Webequie First Nation Reserve lands, with the remainder of the road located on un-surveyed Ontario Crown lands.
The proposed WSR is located in north-western Ontario on un-surveyed Ontario Crown lands and Webequie First Nation Reserve lands approximately 525 km northeast of the City of Thunder Bay as shown in Figure 1.1. The WSR is intended to facilitate the movement of materials, supplies and people from Webequie to the mineral exploration areas near McFaulds Lake area and to connect the community to the provincial road network to the south when the other two road projects (Northern Road Link – NRL; and Marten Falls Community Access Road – MFCAR) will be completed as well. It is expected to accommodate an annual average daily traffic of less than 500 vehicles consisting of light to medium personal vehicles, commercial vehicles and heavier trucks hauling industrial supplies and equipment.
The northwest-southeast segment of the road (51 km) resting mostly over mineral soil will be cleared of all vegetation across the 35 m ROW to accommodate the two-lane all-season road. Shoulders, ditches, and berms of stripped organic materials on the outside will also be shaped along this segment.
The segment of the WSR running in an east-west direction is located within the Hudson Bay Lowlands Ecozone that includes James Bay ecoregion and is composed mostly of peatland (muskeg) having a depth of 2-4 m of waterlogged organic soil, which represents poor to very poor conditions for building a road. A floating road design is therefore considered by adding an underlying layer of aggregates (along with geotextile fabrics or geogrids) that will compress the peat resulting in settlement and consolidation. A surface layer of crushed stone will be added to complete the road that is expected to lay 1.2 m above the surrounding lowland areas.

For the west half of the WSR in stable soil conditions, the surface layer of the road that represents the driving surface for vehicles will be a chip seal treatment, which is similar to asphalt pavement, and consists of a tar slurry and gravel. For the east half of the road in the peatlands with poor soil conditions, it is proposed the driving surface be initially gravel. During the operation phase, monitoring of the east half of the WSR in the peatlands will be conducted to assess performance/settlement, serviceability, and safety issues/concerns related to dust along the corridor. Depending on the outcome of this monitoring, the gravel driving surface may be replaced in a timeframe of approximately 3 to 5 years with a surface treatment such as chip seal treatment, or asphalt pavement.
Other project components will include bridges and culverts to cross waterbodies, road cross-culverts for local drainage, aggregate pits/quarries, rest and maintenance areas along the WSR, and a permanent Maintenance and Storage Facility (MSF) for operation and maintenance of the WSR once operational.

1.2 Valued Component and Indicators
This report discusses air quality as a valued component (VC) that has been identified in the TISG and by the Project Team and is, in part, based on what Indigenous communities, the public and stakeholders have identified as valuable to them in the EA/IA for the Project. Emissions from the project activities during the construction and operation phases will have an impact on existing air quality conditions especially along the WSR to a spatial extent that will be established and discussed in this report. Indicators are used to assess potential effects to air quality. In general, indicators represent a resource, feature or issue related to a VC that if changed from the existing conditions may demonstrate a positive or negative effect. Compounds emitted during the construction and operation phases of the Project that have limits under Ontario Regulation 419/05 – General Air Quality and the Canadian Air Quality Standards (CAAQS) from the Canadian Council of Ministers of the Environment (CCME) are proposed as indicators of changes to air quality. Table
1-1 presents the air quality valued component and indicators and rationale for their selection.

Table 1-1:      Air Quality VC – Indicators and Rationale

The MECP has issued guidelines related to ambient air concentrations that are summarized in Ontario’s Ambient Air Quality Criteria (MECP, 2020). These guidelines represent indications of good air quality, based on protection against negative effects on health or the environment. The guidelines are not regulatory enforceable limits (MECP, 2020).
There are two sets of federal objectives and standards – the National Ambient Air Quality Objectives (NAAQOs) and the Canadian Ambient Air Quality Standards (CAAQSs) (formerly the National Ambient Air Quality Standards [NAAQS]).
The NAAQOs are benchmarks that can be used to facilitate air quality management on a regional scale and provide goals for outdoor air quality that protect public health, the environment, or aesthetic properties of the environment (Canadian Council of Ministers of the Environment [CCME], 1999). The federal government has established the following levels of NAAQOs (Health Canada, 1994):
 The maximum desirable level defines the long-term goal for air quality and provides a basis for an anti-degradation policy for unpolluted parts of the country and for the continuing development of control technology.
 The maximum acceptable level is intended to provide adequate protection against negative effects on soil, water, vegetation, materials, animals, visibility, personal comfort, and well-being.
 The air quality criteria, objectives, or standards described above do not set regulatory limits. Their purpose is to serve as an indicator of good air quality and as a comparison benchmark for monitoring data. Monitoring data in Canada periodically exceeds these criteria, objectives, and standards at different locations. This does not result in an immediate effect to human health but serves as guidance for identifying areas where air quality could potentially be improved.

A detailed description of the relevant provincial and federal criteria, objectives and standards to the Project is provided in Section 2.4.

1.3 Spatial and Temporal Boundaries
1.3.1 Spatial Boundaries
The spatial boundaries for the purpose of characterizing impacts of the Project on air quality include the following.
Local Study Area (LSA) is the area where largely direct, and indirect effects of the Project are likely to occur.

 The LSA extends 1 km from each side of the centreline of the WSR, and 500 m from temporary and permanent supportive infrastructure (construction camps, aggregate/rock source areas, access roads, MSF). This includes the road ROW or Project Footprint of the supportive infrastructure where the majority of sources that will impact air quality are likely to occur.
Regional Study Area (RSA) is the area where potential, largely indirect and cumulative effects of the Project in the broader, regional context may occur.
 The RSA extends 5 km from boundaries of the LSA.

In selecting the LSA and RSA boundaries, consideration was given to potential effects and effect pathways as a result of the Project. For air quality, the effects of the Project activities are considered to be constrained to the LSA spatial boundaries. Sensitive receptors and future land use were considered in the air quality impact assessment. The modelling approach for the assessment focuses on the western portion of the WSR from the community of Webequie to the point where the road intersects with the proposed permanent access road to the ARA-4 aggregate source area (41.5 km). The approach to focus on the impacts to sensitive receptors located in and near the community of Webequie was adopted because the construction and operation of the road is expected to be similar along the full length (i.e., the impacts assessed for the western part will be of similar nature for the eastern part). It was determined that modelling the full road (>100 km) would be computationally time consuming and not provide different results. The spatial assessment boundaries for the air dispersion modelling for the Project are presented in Figure 1.2 and Figure 1.3.

1.3.2 Temporal Boundaries
Temporal boundaries for the assessment address the potential effects of the Project over relevant timescales. The temporal boundaries for the Project comprise the following two main phases:
 Construction Phase: All activities associated with the initial development and construction of the road and supportive infrastructure from the start of the construction to the start of the operation and maintenance of the Project and is anticipated to be approximately 5 to 6 years in duration.
 Operation Phase: All activities associated with operation and maintenance of the road and permanent supportive infrastructure (e.g., operation and maintenance yard, aggregate extraction and processing areas) that will start after the construction activities are complete, including site restoration and decommissioning of temporary infrastructure (e.g., access roads, construction camps, etc.). The Operations Phase of the Project is anticipated to be 75 years based on the expected timeline when major refurbishment of road components (e.g., bridges) is deemed necessary.
The Project is expected to operate for an indeterminate period; therefore, future suspension, decommissioning and eventual abandonment is not evaluated in the EA/IA or this air quality assessment.

1.4 Identification of Project Interactions with Air Quality
Table 1-2 identifies project activities that may interact with air quality VC to result in a potential effect. The identification of project interactions with air quality VC provides a basis for the subsequent assessment of the potential effects of the Project.
Table 1-2: Project Interactions with Air Quality VC

Table 1-2 (cont’d): Project Interactions with Air Quality

Notes:
✓ = Potential interaction – = No interaction
1 Emissions, Discharges, and Wastes (e.g., air, noise, light, solid wastes, and liquid effluents) can be generated by many project activities. Rather than acknowledging this by placing a checkmark against each of these activities, “Wastes and Emissions” is an additional component under each project phase.
2 Accidents and Malfunctions including spills, vehicle collisions, flooding, forest fire and vandalism may occur at any time during construction and operations of the Project. Rather than acknowledging this by placing a checkmark against each of these activities, “Potential for Accidents and Malfunctions” is an additional component under each project phase. The potential effects of accidental spills are assessed in Section 23 – Accidents and Malfunctions.
3 Project employment and expenditures are related to most project activities and components and are the main drivers of many socio-economic effects. Rather than acknowledging this by placing a checkmark against each of these activities, “Employment and Expenditures” is an additional component under each project phase.

1.5 Scope of the Air Quality Assessment
The objective of the air quality assessment is to verify how the Project would impact the ambient air quality around the road and near supportive infrastructure and if there is risk of exceeding a CAAQS or ambient air quality criteria (AAQC) applicable in the province of Ontario.
As required in the TISG, studied contaminants include the common air contaminants (CAC) as well as specific toxic contaminants from the volatile organic compound (VOC) category and polycyclic aromatic hydrocarbons (PAH). The CACs include the nitrogen oxides (NOx, and more specifically nitrogen dioxide (NO2)), carbon monoxide (CO), sulphur dioxide (SO2), and particulate matter of different diameter classes (total suspended particulate (TSP), inferior to 10 µm (PM10) and inferior to 2.5 µm (PM2.5)). The complete list of toxic contaminants covered in this assessment is presented in Section 2.4 and includes DPM. The air dispersion modelling study will also assess the extent of dustfall during the construction and operation phases of the Project.
The emission sources covered in this assessment come essentially from the combustion of diesel fuel or gasoline from land mobile equipment, heavy-duty trucks and light-duty vehicles during the construction and operation phase of the WSR. Table 1-2 has provided the project activities that may interact with air quality and result in a potential effect. The

modelling exercise also considers fugitive dust emissions mostly from vehicular traffic on the road and the handling of aggregates and other earth materials during construction. The methods and inputs used in calculating emission rates are presented in Sections 3 and 4 of this report. Other than the usual air dispersion modelling requirements, specific instructions were also given in the TISG for this assessment, and include the following:
 Provide an assessment of the project’s emissions potentially contributing or adding to existing ground ozone levels.
 Assess the potential for emissions from the Project to contribute acid deposition and exceedances of critical loads for terrestrial and aquatic ecosystems.
 Provide emission rates for all project and regional sources within the study area, including emission factors
(with methodology, uncertainty assessment and references) and all assumptions and related parameters that would enable calculations to be reproduced.
 Provide a comparison of predicted air quality concentration against the CAAQS for PM2.5, SO2 and NO2, and ozone (O3). Predicted concentrations for other air pollutants relevant to the project, such as dust resulting from construction activities and ongoing vehicle use during operations or maintenance of the road, should be compared with appropriate provincial and territorial guidelines.
 Provide a description of all methods and practices (e.g., dust suppression strategies and guidelines, control equipment) to be implemented to reduce and control emissions. If the best available technologies are not included in the Project design, the proponent needs to provide a rationale for the technologies selected.
 Provide details of the achievement of emission standards for all mobile and stationary engines used in the Project.

This report contains five sections including this introduction as follows:

 Section 2 provides details on methods used for air dispersion modelling (meteorology, topography, receptors, etc.).
 Section 3 and Section 4 deal with the project’s construction and operation phases respectively, by defining emission scenarios based on identified sources, calculation inputs and modelled emission sources configuration. Modelling results are presented at the end of each section and compared with AAQC and CAAQS.
 Section 5 discusses about uncertainties associated with this work.
 Section 6 discusses about the potential effects and interactions of the Project on air quality.
 Section 7 discusses on the proposed mitigation measures and predicted net effects on air quality.
 Section 8 provides concluding remarks.

2 Modelling Methodology
The method used for atmospheric dispersion modelling meets the requirements of the Atmospheric Dispersion Modelling Guide for Ontario (ADMGO) from the MECP (2017) and considers the recommendations of the US EPA (2017, 2023a) for the selected dispersion model. The following subsections present the technical details of the atmospheric dispersion study. Modelling details specific to the construction and operation phases, mainly the definition of sources and their emission parameters, are presented in Section 3 and Section 4, respectively.

2.1 Air Dispersion Model
The choice of dispersion model used for this assessment is based on regulatory requirements (i.e., ADMGO), depending on the location of the project and the availability of specific data needed to feed the models. The American Meteorological Society and Environmental Protection Agency Regulatory Air Dispersion Model (AERMOD version 22112, the most recent adopted by MECP) is suggested for this assessment. This model is regularly used in air quality impact studies for industrial projects in Ontario and elsewhere in the world. This is in fact the regulatory model in the United States and several Canadian provinces, and the model usually used in Ontario. The MECP guide designates AERMOD as the preferred model for dispersion studies at the close or local scale (< 50 km).
The AERMOD model is updated regularly. It is an advanced Gaussian-type steady-state plume model that considers two-dimensional meteorological fields (vertical variability and uniformity in the horizontal plane), as well as the interaction of the topography with the plumes of the sources of air contaminant emissions. AERMOD allows the building wake to be considered and integrates the elevation due to the amount of vertical movement and buoyancy of the hot gases escaping from sources. Finally, the model also takes into account hourly variation in meteorological parameters and temperature inversions on the ground or at altitude.
For the WSR Project, emission sources will be located close to the ground and therefore the maximum potential impacts on air quality will occur close to the project site (local scale). Given the absence of significant topography or very large bodies of water (such as the Great Lakes or an ocean) in the study area, the assumption of uniformity in the horizontal plane of meteorological fields is justified and therefore it is not required to use a dispersion model considering three-dimensional meteorology or for longer-range transport such as the CALPUFF model. The AERMOD model is also preferred for the following reasons:
 For most of the project’s emission sources, the transport of air contaminants from the source and receptors will be over land in forested areas.
 The MECP’s ADMGO requires that large water bodies with shoreline effects be accounted for with the use of an advanced model. However, the lakes and rivers along the WSR Project are not considered sufficient enough to impact the ground-level vehicle and construction equipment sources and does not justify the use of a more advanced dispersion model such as CALPUFF.
The model’s input data includes:

 Emission characteristics (emission rate of various contaminants, exhaust flow rate, temperature, velocity, etc.).
 Characteristics of emission sources (location, stacks height and diameter, dimensions, etc.).
 The characteristic dimensions of the buildings if the effects of building wakes on the stack plumes are considered; however, there were no buildings considered in the WSR model.
 Hourly meteorological data (temperature, wind speed and direction, atmospheric stability, and turbulence indices, mixing height).

 The position and elevation of the receptors, i.e., the places where the atmospheric concentration of the contaminant is to be assessed.
 Parameters controlling the model options and statistical calculations to be performed on the concentrations or deposition rates calculated by the model.
For this assessment, the AERMOD model was used with the default “regulatory” options in rural mode for all sources, as required by the MECP for calculations of contaminant concentrations in ambient air. Land cover within a 3 km radius of the Project is forested and undeveloped.
For the NO2 contaminant, some simulations with the AERMOD model were performed considering the conversion of nitrogen monoxide (NO) into NO2 using «Ozone Limiting Method (OLM)». More details are provided in Section 2.6.
Ambient air concentration of TSP and particulate matter deposition (dustfall) from fugitive sources uses the option of plume depletion by deposition. Neglecting plume depletion of particulate matter sources by dry deposition for PM10 and PM2.5 is a conservative assumption, which does not have much impact on the modelling results, since these particles are very gradually deposited. The dispersion model options used are summarized in Table 2-1.
Table 2-1: Options Used in AERMOD

2.2 Meteorological Dataset

Meteorological parameters impacting atmospheric dispersion considered by the AERMOD model are the wind speed and direction, atmospheric stability indices (friction velocity, Monin-Obukov length) and mixing height. These parameters, as well as the ambient temperature, are provided to the model on an hourly basis for a period of 5 years. For estimating wet deposition of particulate matter, hourly precipitation data are also required.
Regional meteorological data for a period of five consecutive years (1996-2000) was obtained from the MECP prepared meteorological data set available for northern Ontario. The International Falls dataset was developed using land characteristic for northern Ontario (forest) and surface and upper air data. The prepared data sets provide meteorological data that is representative and meets the data quality requirements as per the ADMGO. This follows a similar approach presented in the Eagle’s Nest Project Air Quality Technical Supporting Document (Knight Piésold, 2013) that was part of the draft Environmental Impact Statement for the proposed development of the mine near McFaulds Lake.
Figure 2.1 shows the annual compass rose for the period 1996 to 2000. At a height of 10 m, the prevailing winds
(the most frequent directions) are from the west (21.6%), southwest and south (21.3%). In other words, the wind blows from the location of the project towards the north and east with a frequency of 53% (NE, ENE, E and ESE directions). This frequency increases in the summer and fall (June-December). The average wind speed is 3.68 m/s (13.3 km/h), and the frequency of calm winds is 0.20%.
Figure 2.1: Annual Wind Rose 1996-2000 at International Falls Station Used in the Model

Figure 2.2. Seasonal Wind Rose 1996-2000 at International Falls Station

International Falls meteorological dataset was selected as there were no other existing meteorological station with a full 5-year set of data. That said, wind roses from closest stations to the site show similar characteristics as the International Falls data (Figure 2.3). Pickle Lake located 258 km to the southwest of Webequie has a similar average wind speed (13.1 km/h) and prevailing winds from the western quadrant. Lansdowne House located 91 km south of Webequie has a slightly lower average wind speed (10.5 km/h) but also prevailing winds from the western quadrant. Although there are some differences in wind speeds and directions, it is expected that the range of weather conditions are representative of the range of conditions that will occur along the length of the Project (~100 km from Webequie to the Mine Camp).

Figure 2.3. Annual Wind Roses at Meteorological Stations Closer to Site

2.3 Modelling Domain
Given the long road distance, the modelling domain was restricted within an area of about 30 km by 30 km that covers
40.5 km of the 107 km road from the community of Webequie to the point on the road where it intersects with the ARA-4 aggregate pit access road (refer to Figure 1.2). This modelling domain was selected to focus on the impacts within a corridor along the road but also on sensitive receptors (i.e., residences, institutional buildings, and culturally sensitive areas) that are more sizeable in this area. In fact, the majority of sensitive receptors are located in the modelling domain and the impacts along the road are expected to be similar for the remaining length (i.e., ~66 km not included in the model). In addition, the computational time required to assess the full length of the road at the proposed resolution would have been prohibitive (i.e., modelling a shorter length allows for a better resolution and understanding of local impacts).
For the construction and operation phases, the receptors, or points of impingement, for contaminant concentrations in ambient air, were arranged along the road with the resolution as follows (1,649 receptors):

1. Every 100 m at 50 m distance from the road centreline on either side; and,
2. Every 100 m at 150 m distance from the road centreline on either side.

This configuration provides means to generate lateral concentration profile within a distance of 150 m from the road centerline where the bulk of emissions will occur. Extra arrays of receptors along the road further away would have not provided further informative details giving that the road is located in a remote area. That said, the impact of the project emissions at specific points of impingement outside the 150 m corridor was verified. Discrete receptors (146) were placed at the noise sensitive areas (NSAs) identified for the Project, which are also considered sensitive in terms of air quality and dustfall. These locations include the following:
 Twenty-four (24) existing residences or group of residences (RP) including mostly homes within the community of Webequie.
 Six (6) institutional buildings (I) including two schools, a nursing station, a church, a community building, and business center.
 Twenty-one (21) culturally sensitive areas (CHL) including spiritual or sacred spaces for members of the Webequie First Nation and other Indigenous communities and/or stakeholders. It includes locations important for harvesting country-food/plans or hunting. Since being areas, receptors were placed at intervals along the closest edge of these areas to the WSR to assess potential impacts. The modelling results discussion will focus on the impacts at these discrete receptor groups and along the road.
 Sixty-six (66) locations for future residences (RPF) per the Webequie First Nation On-Reserve Land Use Plan of 2019 distributed amongst four areas (Site A; Site West; Site C and Site D).
The receptors locations as part of the air quality assessment are illustrated in Figure 1.2 and Figure 1.3.

Local topography was considered in the modelling. Canada’s 1:50,000 scale digital elevation data with an approximate resolution of 20 m was processed using the AERMAP processor to extract elevations for sources and receptors and to calculate terrain slopes.

2.4 Relevant Air Quality Criteria and Standards
The Ontario Ambient Air Quality Criteria (AAQC) and the Canadian Ambient Air Quality Standards (CAAQS) for contaminants relevant to the Project are presented in Table 2-2. The Nunavut Air Quality standards (NAAQS) are also shown for comparison purpose only. As shown, they are higher or at least equivalent to corresponding provincial and
/or federal limits.

Studied contaminants include all the CACs as well as toxic contaminants like aldehydes, specific VOCs, and PAHs with an AAQC that can be found in exhaust gases from vehicles and mobile equipment. The AAQC dustfall limit is considered as a guideline in this assessment to inform the reader of the extent of dust deposition associated with the project on the surrounding environment. No metals were modelled as there are no information about their content in soil and aggregates that will be handled on site. As requested by the TISG, DPM was modelled representing all PM2.5 generated by engines. No criteria or standard is associated with DPM, but since it is recognized as carcinogenic, annualized (long-term impact) concentrations were simulated.

Table 2-2: Ambient Air Quality Criteria and Standards for Studied Contaminants

Notes:
As the geometric mean of daily measurements over a year.
(1) The 3-year average of the annual 98th percentile of the daily 24-hr average concentrations.
(2) The 3-year average of the annual average concentrations.
(3) Applicable starting in 2025. The 3-year average of the annual 99th percentile of the SO2 daily maximum 1-hour average concentrations.
(4) Applicable starting in 2025. The average over a single calendar year of all 1-hour average concentrations.
(5) Applicable starting in 2025. The 3-year average of the annual 98th percentile of the daily maximum 1-hour average concentrations.
(6) B[a]P is used as a surrogate for the total carcinogenicity of PAHs. While the annual value corresponds to the AAQC annual standard, the 24- hour value corresponds to the daily modelling assessment value (DAV) (also known as the Upper Risk Threshold (URT) for BaP) instead of the AAQC daily standard of 0.00005 g/m3 which is applicable to monitored concentration data.

2.5 Summary of Existing Conditions
The proposed WSR is located in a remote region of northern Ontario away from significant sources of human induced air emissions. For the study area, air emission sources are limited to the community of Webequie of which can be summarized with assumptions as follows:
 Electric power station with diesel generator sets having a capacity of 2 MW producing an estimated 3,000 MWh of electricity per year (Government of Canada, 2024). According to the National Pollutant Report Inventory (NPRI), the power plant generates a total of 50 to 70 tonnes of NO2 annually and 1 tonne or less of micro particulates (PM10 and PM2.5).
 The combustion of wood residues in stoves or equipment alike for heating purposes in Webequie, generating particulates, NO2 and VOCs from combusted wood. Natural gas and propane are not available in the community.
 Mobile vehicles (trucks, snowmobile, all-terrain vehicles, dozers, etc.) are most likely used within the community but the related emissions should be relatively low.
 Solid wastes are disposed in a nearby community landfill which can release greenhouse gases (GHG) but also an array of VOCs. Given the population number (and organic waste generation rate), the resulting fugitive emissions from the landfill are most likely very small. No open burning of wastes commonly occurs in Webequie.
 The Webequie airport links the community to other regions in Ontario providing air transportation services for the local population, including delivery of goods and services. Aircrafts will generate an array of air contaminants, although mostly in the upper atmosphere.
There are no industrial or mining activities in the study area presently. The closest installations that have reported emissions to the NPRI (and therefore have exceeded the reporting threshold) are other thermal power plants operated by Hydro One (in Kasabonika and Landsdowne House at 100 km from Webequie). The closest active mine (Musselwhite Mine, Goldcorp Canada Ltd.) that have reported emissions to the NPRI are located at over 200 km from Webequie. There are no large-scale agricultural activities, and the commercial forestry industry is not active within the LSA or RSA.
Local air quality data is not available with the exception of limited data collected from a station operated by the MECP (2019) as part of Ontario’s Ring of Fire Baseline Monitoring Program (2013-2017) providing data on fine particulate matter (PM2.5) and metals which are excluded from this assessment. For the other contaminants, a combination of air quality monitoring stations located in remote areas similar to the Project were used to characterize and describe existing air quality conditions in the LSA and RSA. The monitoring stations are part of the Réseau de surveillance de la qualité de l’air du Québec (RSQAQ) and the National Air Pollution Surveillance Network (NAPS). Table 2-3 lists the background concentrations selected as part of this assessment relevant to the AAQC or CAAQS averaging period.
They are based on data that was presented in the Natural Environment Existing Conditions Report (hereafter referred to as the “Baseline Report”) prepared for the Project by AtkinsRéalis Canada Inc. (AtkinsRéalis, 2024)
(formerly SNC-Lavalin Inc.). General remarks on the potential presence of contaminants in the RSA (within 6 km from the road on each side) are as follows:
 Gaseous common air contaminants: The annual average SO2, CO and NO2 background concentrations in remote areas without industrial or manufacturing installations are expected to be low (< 1 ppb for SO2; 200 ppb for CO; and < 3 ppb for NO2) compared to applicable air quality criteria and standards, but can still reach higher values and peaks especially during wildfires (near or from further away due to high atmosphere dispersion), prescribed agricultural or biomass burns in the area, or in the case of Webequie, in the direct vicinity of the diesel power plant.
 Ground-level O3: Concentrations measured at regional background monitoring stations are all similar in range, with no exceedances observed in comparison to the applicable criteria and standards. Annual mean concentrations in Webequie can be expected to be similar to those reported at stations in remote area, that is in the 25 to 30 ppb range.

 Particulate matter: Like for gaseous contaminants, particulate matter in remote areas will come mostly from the combustion of trees and vegetation, from diesel fuel combustion at the power plant and also, depending on location, from wind lifting of naturally or anthropogenically eroded surfaces that tends to generate concentration peaks in the summer months. The use of wood stoves or equivalents is another source of particulates and micro-particulates that is limited to the community.
 Toxic contaminants: Carbonyls, VOCs and PAHs are also attributed to fuel and wood combustion. Higher concentrations will be observed during the cooler months which may be attributed to wood burning in the area but also by the fact that cooler air and inversions trap contaminants near the ground.
The atmospheric dispersion model provides estimates about the project’s contribution to contaminant concentrations in ambient air. Background concentrations account for air contaminants already present in the environment or from other sources. The background concentrations presented in Table 2-3 are therefore added to the model results so to compare the resulting concentrations with applicable air quality standards and criteria.
Table 2-3: Summary of Background Concentrations for Studied Contaminants

Table 2-3 (Cont’d): Summary of Background Concentrations for Studied Contaminants

Notes:
(1) Although in a non-urban setting without any significant emission sources nearby, data comes from a station located in southern Ontario which most likely over-estimate the actual background concentration of VOCs in the study area.
(2) Background 1-hour concentration multiplied by 1.65 for the 10-minute averaging period or 1.2 for 30-minute averaging period.

Dustfall

The TISG for the Project requires a description of background dust deposition conditions in the study area, but like air contaminants, no local measurements are available to our knowledge. Background dustfall (in t/km2/30-days) can be broadly estimated by associating TSP concentrations in air with dust deposition on the ground at a same location. A study was carried out in the past (Roche, 1983) which presented average dustfall rates and TSP concentrations for several years at multiple stations within the City of Quebec. Figure 2.4 illustrates the almost linear relationship between these two variables over several years. Assuming the average TSP concentration in the study area is 4.0 µg/m³
(Table 2-3), then it would be expected according to this correlation that dustfall would approach 0.40 t/km²/30-day. This value is therefore considered as background dustfall in this assessment.
Figure 2.4: Relation between mean TSP concentrations measured in air and mean dust deposition measurements carried out at 12 stations in Quebec City from 1979 to 1982

(adapted from Roche, 1983)
Shaded: 95% confidence interval for average estimations Red line: 95% confidence interval for single estimations

2.6 Nitrogen Dioxide: NO Conversion into NO2
NOx emissions comprise NO2 but also NO. The relative proportions of NO and NO2 from engine’s exhaust gases are respectively 90% and 10%. In air, the NO is converted more or less rapidly into NO2 depending mainly on O3 concentration in the atmosphere along with meteorological conditions. In contrast, NO2 photodissociation from solar radiation will produce O3 and NO. Since there are no air quality standards for NO, only NO2 concentrations need to be assessed.
For this assessment, the hypothesis that all NO is converted into NO2 at emission sources is applied for the calculation of maximum daily and annual concentrations, resulting in conservative NO2 concentrations.
For the verification of 1-hour NO2 CAAQS and AAQC, the «Ozone Limiting Method» (OLM) is applied to calculate maximum 1-hour NO2 concentrations based on the dispersion model results and O3 concentrations in air while supposing that 10% of total NOx are released as NO2. The background O3 concentration representative of the study area as presented in the Baseline Report was selected for this purpose (55 µg/m³ or 28 ppb).
 If [O3] > 0.9 x [NOx] then [NO2] = [NOx] Total conversion
 Otherwise: [NO2] = [O3] + 0.1 x [NOx] Partial conversion

2.7 Dry Deposition Parameters on Dust Emissions
In this assessment, dustfall and TSP concentration in air were calculated using the dry depletion mechanism for fugitive dust generated during construction activities and vehicle traffic on the road since these emissions contain large portions of coarse particulates (10 to 30 µm) for which deposition is an important phenomenon. Depletion of particulate matter from engines was ignore since this type of emission generate fines particulates which falls very slowly and over long distances.
The dispersion model requires distribution and grain density data per particulate diameter class. Emission factors from the US EPA AP-42 Compendium used for the estimation of fugitive dust emissions were also used to define three to four particulate diameter classes depending on the source. Selected dry deposition parameters are presented along with the emission source parameters for the construction phase (Section 3) and operation phase (Section 4).

2.8 Averaging Conversion Factor
Some of the AAQC limits are less than an hour in duration (e.g., 10 minutes for SO2) while the dispersion model results are representative of a duration of one hour or more. The formula specified in the ADMGO (MECP, 2017) is used to estimate the maximum concentrations over 10 minutes from the maximum hourly concentrations obtained from the dispersion model. The hourly maximum results will therefore be multiplied by a factor of 1.65 and 1.2 for the estimate of a maximum concentration over 10 minutes and 30 minutes (1/2 hour), respectively.

3 Construction Phase
The construction of the WSR will be conducted all-year round over an approximately 60-month period by team of workers that will set camp at one of four locations planned along the 107 km WSR. The detailed construction staging and sequencing of the Project will be determined in the Detail Design phase through discussions between Indigenous communities and the construction contractor. It is anticipated that road construction will be linear starting from the first construction camp (expected to be located at 15 km south-east from Webequie) running west towards Webequie and then running east towards McFaulds Lake. The workers will commute daily from the construction camp to location.
The WSR will consist of two distinct segments, one of 51 km from Webequie running south-easterly and then of 56 km running east until it terminates near the McFaulds Lake area. The first segment (western half of the WSR) resting mostly over mineral soil will be cleared of all vegetation within the 35 m ROW for the road to accommodate the two-lane all-season road. Shoulders, ditches (as enhanced grass swales) and berms of stripped organic materials on the outside will also be shaped along this segment. Cut and fill earthworks will be needed to adjust the vertical alignment by either lowering or raising the existing grades. An underlying layer of aggregates and a surface layer of crushed stone will then be conveyed by trucks from a nearby quarry and compacted on site by heavy machinery. A layer of chip seal or asphalt pavement will be also added onto the road surface.
The eastern segment of the WSR being located within the Hudson Bay Lowlands Ecozone is composed mostly of peatland (muskeg) having a depth of 2-4 m of waterlogged organic soil, which represents poor to very poor conditions for building a road. A floating road design is being recommended by adding an underlying layer of aggregates
(along with geogrids) that will compress the peat resulting in settlement and consolidation. A surface layer of crushed stone will be added to complete the road that is expected to lay 1.2 m above the surrounding lowland areas.
Cross-culverts will be integrated within the road structure at regular intervals to ensure that the hydraulic conductivity of the peatlands is maintained.
Some watercourse crossings will require steel-concrete bridges that will include a substructure composed of a foundation, abutments and piers supporting the superstructure consisting of steel plate girders, the deck and side barriers with railings. Natural revegetation, seeding and/or planting will be done on and around the embankments once the bridge is completed. Several culverts will also be fitted to cross minor watercourses.
Aggregates and crushed stones will come from two source locations, one of which will be used exclusively during the construction phase (ARA-2) and another (ARA-4) which lifespan will extend during the operation phase to provide aggregates for operations and maintenance of the road. Production activities will include hole drilling, blasting, and rock conveyance to a nearby crushing plant that should include a primary crusher, a secondary crusher, a screening plant, diesel generators, conveyors, a control tower and supporting mobile loaders. The ARA-4quarry, being in an area far from the WSR, will necessitate the clearing and construction of an access road of 5 km, which will include the crossing of a waterbody.
Progressive rehabilitation work will be carried out along the WSR as well as at the ARA-2 quarry and the worker camps when construction work is completed or almost completed. The closure of temporary construction camps and laydown areas will involve its clean-up (material, waste, and contaminated soil removal) followed by the levelling and trimming the areas to encourage natural revegetation.

3.1 Modelled Emission Sources
The scope of work during the construction phase comprises all activities that will occur along the WSR, the aggregate pits and the access road (refer to Table 1-2. Construction activities that result in potential effects will mainly consist of:
 Vegetation clearing, grubbing and disposal.
 Setup of storage and laydown yards, and construction camps.
 Earth stripping along the ROW, the aggregate pits, and the access road.
 Aggregate production (crushing and screening) including hauling to site.
 Road construction including grading, aggregate placement, ditching, geotextile installation, and ditch seeding.
 Chip seal or asphalt placement of the road.
 Bridge construction and culvert installation including the operation of a concrete batching plant.
 Construction of buildings and storage areas at the MSF.
 Maintenance of environmental structures/measures (e.g., erosion and sediment control measures), including drainage management features on access roads.
Sigfusson Northern Ltd. as construction support to the EA/IA for the Project developed a preliminary plan of activities during a 60-month construction period, including a list of equipment and materials needed to complete the work (Sigfusson, 2023). Table 3-1 shows the activities and areas of work presented in Sigfusson’s assessment per phase and the planned realization and time required within that period to achieve the work.
Using this information an emission scenario was developed for the first year of construction (winter #1 + summer #1) selected amongst all years for the following reasons:
 Year 1 will operate the greatest number of mobile equipment (bulldozers, excavators, loaders, cranes, etc.) in terms of month-equipment on site.
 The majority of activities during Year 1 will be focused between the western terminus (Webequie) and the ARA-2 quarry which is close to the WC-3 water crossing, down to the access road/WSR intersection which represents the eastern point of the modelling domain. This area regroups the great majority of sensitive receptors (existing residences and institutional buildings, culturally sensitive areas, and future residences planned by the Webequie First Nation).
 Based on numbers from Table 3-1, aggregates trucking from ARA-2 and ARA-4 quarries will be more intensive during Year 2 compared to Year 1. However, a great majority of Year 2 trucks will travel east of the access road/WSR intersection (outside the modelling domain). Trucking along the modelling domain would remain slightly higher during Year 2 but not to a great extent. For that reason, Year 2 trucking was combined in the emission scenario along with the other Year 1 emission sources, as a cautious approach.

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Notes:
(1) ARA-2: site of a temporary quarry; ARA-4: site of the permanent quarry; WB and WC: water crossings where culverts or bridges will be constructed.
(2) Monthly periods were inferred from Sigfusson’s report schedule per activity.
(3) Number of mobile equipment planned on site x the number of months projected to carry out the activity. Excludes crew support equipment and stationary combustion equipment which number is more or less constant throughout the construction phase.
(4) Volume (m3) of aggregates and filling materials or surface area (m2) of geotextile (geogrids) that will be hauled to location.
(5) Include loading of aggregates at the quarry, hauling and placement on site.
The impact of Year 2 to 5 activities during the construction phase was not assessed as they involve the same emission sources as modelled for Year 1 only at different locations and different extents (i.e., varying number of trucks, different number of equipment to carry out the work based on Sigfusson’s planning). Since the emissions are limited along the WSR 35-m wide ROW, the concentrations in air will be of similar profile whether being on the western or eastern portion of the road. Also, as explained above, there are no sensitive receptors east of the WSR / access road intersection for ARA-4, with the exception of one location where potential impacts are discussed in Section 5.

3.2 Modelling Approach for Assessment
A majority of emission sources will not be static and will move along the WSR during the construction phase. In order to verify the air quality impact of road construction activities between the western terminus (Webequie) and the eastern point within the modelling domain (intersection between the WSR and the ARA-4 access road), an approach combining emission rates from all equipment and activities that could occur within a specific area (as a volume source) was considered. The intent was to mimic this same volume along the road at 300 m intervals to verify the potential impact of these activities at all locations with regard to standards with an averaging period of 24-hours or less. For example, the exhaust gas emissions of all equipment expected during “clearing and grubbing” are combined within a single source (A1; see Table 3-2) and positioned at several locations (300 m interval) between Webequie and the WSR/access road intersection. This approach is applied for emissions that can occur at different locations. Otherwise, a single volume source is applied for fixed locations associated with aggregate production, culvert installation and bridge construction (Table 3-2). For monthly (dustfall) and annual averaging periods, the emission rates applied at each volume were weighted down to consider the fact that emissions will occur only for a short period at each location. More details on emission rates are presented in Section 3.3 for each source.
Results were calculated based on a scenario without particular emission control measures and a similar scenario with control measures which, for the construction phase, concerns fugitive road dust control with a water truck (Section 3.3.3) and the operation of most recent machinery (Section 3.3.1). Table 3-2 provides an overview of equipment and activities including the model based on the construction planning during Year 1 (or Year 2 for trucking) that will result in atmospheric emissions. Calculation of emission rates is mostly based on these data. The distribution of emission sources within the modelling domain is shown in Figure 3.1.

3.3 Emission Rate Calculations
The following subsections summarize the approach used to obtain emission rates for each contaminant covered in this assessment. The first two subsections deal with contaminants emitted from exhaust pipes on mobile equipment and trucks carrying aggregates, fill material, and material – geotextile (geogrid) along the road. The next subsections then present the methods to calculate fugitive dust emissions from the road, aggregate crushing at the quarry, aggregate loading and unloading with trucks, dozers and graders operation, and blasts at the quarry. In this assessment, engine emissions and fugitive dust emissions from a same activity (e.g., trucking, bulldozing, grading) were modelled separately since they present different emission characteristics.

3.3.1 Mobile and Stationary Equipment
Compression-ignition engines on heavy machinery generate several air contaminants including CACs and VOCs. Their emission rates are conditioned by the engine applied power and the regulatory requirements when the equipment was put on the market (Off-road Compression-Ignition (Mobile and Stationary) and Large Spark-Ignition Engine Emissions Regulations). These requirements set in 2005 vary according to the engine gross power and the year of fabrication (categorized in Tiers).
The emission factors for Tier 3 engines (typically constructed between 2006 and 2016) operating in equilibrium (g/hp-h) for the CACs (TSP, NOx, CO, SO2, and total hydrocarbons (THC)) were obtained from latest MOVES4 (Nonroad) model from the US EPA (2021) and applied to all equipment brought to site. This represents a worst-case (scenario without control measures) since it is expected that a large portion of engines will be certified Tier 4 by the time construction activities starts. In fact, considering the relative short lifespan of machinery, it is expected that Tier 4 equipment will represent at least 80% of all equipment. Given the great number of equipment that will be in operation (see Table 3-2 for the list during Year 1), a second emission scenario for which 80% of the equipment were randomly specified to have Tier 4 engines was set up to verify the impact on air quality compared with the case with Tier 3 engines only.
The emission factors were corrected to integrate the engine’s transient operating regime according to equipment type and a maximum deterioration factor as presented in US EPA (2021). Finally, TSP and SO2 emission factors were corrected with respect to sulphur content in diesel fuel. In this assessment, a concentration of 15 mg/kg is used, which is equivalent to the maximum allowable in fuel for use in road and off-road vehicles (Sulphur in Diesel Fuel Regulations).
Table 3-3 provides an example of resulting emission factors based on the US EPA Nonroad model for Tier 3 and 4F engines. The emission factors for the other equipment are available in Appendix A. The emission factors for the other contaminants covered in this assessment were obtained as follow:
 PM10: Equivalent to TSP according to US EPA (2021)
 PM2.5: Equivalent to 97% of TSP according to US EPA (2021)
 DPM: Equivalent to PM2.5
 VOCs: Calculated based on the THC emission factor multiplied by the fraction of the COV in THC. The fractions were inferred from data provided in Table 3-4 (ratio of contaminant in total VOCs) and Table 3-3 (ratio total VOCs in THC) from US EPA (2023b) technical document “Speciation profiles and toxic emission factors for Nonroad engines in MOVES4”.
 B[a]P (as surrogate for PAHs): Calculated based on the THC emission factor multiplied by the fraction of the PAH in THC and the PM2.5 emission factor multiplied by the fraction of B[a]P in PM2.5 which is inferred from data provided in Table 3-5 (ratio of PAH in PM2.5) from US EPA (2023b) technical document “Speciation profiles and toxic emission factors for Nonroad engines in MOVES4”.

3.3.2 Trucking (road engines)
Trucking will be required to transfer aggregates or fill material from quarries and materials such as geotextile from the Webequie area to the road construction site. During winter period, a total of 13 200 m3 of fill material will be hauled during Year 1. For the summer, trucking during Year 2 is considered instead as more passages specifically along the Webequie to the intersection of the WSR/ARA-4 access road intersection will be required during that year. Three (3) routes with different emission rates were developed for this category:
 A6: 13,200 m3 of filling material hauled from Webequie to the WB-1 water crossing during the winter phase.
 A7a: 166,960 m3 of aggregates from ARA-2 to the construction site along the road towards Webequie.
 A7b: 124,330 m3 of aggregates from ARA-2 to the construction site along the road towards the WSR/ARA-4 access road intersection.
Table 3-5 provides an overview of parameters used to estimate the travelling distances expected from trucks. These distances are then combined with CACs emission factors (TSP, NOx, CO, SO2, THC) applicable to on-road trucking (g/km). They were obtained from the US Bureau of Transportation Statistics (2023) compiling average emission factors according to the MOVES4 model by vehicle type and year of operation. The emission factors presented in Table 3-6 relate to heavy-duty vehicles using diesel fuel for year 2020 (representing conservative values as average emission factors in future years tend to decrease). The emission factors for the other contaminants covered in this assessment were obtained as follow:
 PM10: Equivalent to TSP
 PM2.5: Equivalent to 92% of TSP
 DPM: Equivalent to PM2.5
 SO2: Estimated based on the energy consumption efficiency provided by the US Bureau of Transportation Statistics (BTS, 2023) heavy-fuel trucks in 2020 using diesel fuel with a sulphur content of 15 ppm.
 VOCs: Calculated based on the THC emission factor multiplied by the fraction of the COV in THC. The fractions were inferred from data provided in Table 3-5 for vehicles constructed in 2017+ (ratio of contaminant in total VOCs) and a ratio of 1.285 COV/THC from US EPA (2020) technical document “Air Toxic Emissions from On-Road Vehicles in MOVES3”.
 B[a]P (as surrogate to PAHs): Calculated based on the PM2.5 emission factor multiplied by the fraction of B[a]P in PM2.5 which is inferred from data provided in Table 3-5 for vehicles construction in 2017+ (ratio of PAH in PM2.5) from US EPA (2020) technical document “Air Toxic Emissions from On-Road Vehicles in MOVES3”.

Table 3-5: Trucking Scenario Considered in the Model

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3.3.3 Vehicular Dust Emissions
The passage of vehicles will generate dust plumes in their wake. Although light-duty trucks transporting workers and tools will generate such emissions, it is not included in the model given that their frequency of passage cannot be properly determined and that their emissions will nonetheless be very small when compared to the recurring passage of heavy-duty trucks (12-wheelers) transporting aggregates and fill material. Dust emissions from the passage of
heavy-duty trucks during the construction phase were therefore estimated according to the method suggested in the US EPA AP-42 Emission Factors Compendium Series for unpaved roads (US EPA, 2006a).

EF: particulate matter emission factor (g/km)
k, d, c: granulometric factors for TSP, PM10 or PM2.5 S: silt content on-road surface (%)
V: truck speed (mph)
M: road surface moisture (%)
CF: dust emissions control factor (%)
Road silt (fine fraction < 75 µm) is set to 5.0% which represents 50% of the maximum allowed amount of fine aggregates in freshly crushed Granular A from quarried materials composing the road surface (maximum of 10% with diameter of 4,750 µm and less according to Ontario Provincial Standards Specifications). Truck speed and road surface moisture were set to 31 mph (50 km/h) and 1.5%, respectively, the latter because aggregates usually contain small amounts of moisture (1 to 2%) in dry conditions.
Water trucks will be available on site to control dust emissions on roads and other working locations. The applied control factors were derived according to Environment and Climate Change Canada (ECCC, 2024) “Road dust emissions from unpaved surfaces: Guide to reporting” which considers overall control factors on a monthly and annual basis adjusted according to the number of days with precipitations greater than 0.2 mm and/or days with freezing conditions (maximum daily temperature below the freezing point) with 100% control for both instances.

Pickle Lake were used to establish overall control factors (being the closest location with data to the project). It also shows the control factors considered for a second scenario without control measures (water trucks). The fugitive dust emission rates (TSP, PM10 and PM2.5) were then derived from the emission factors as above (g/km) and the total distance travelled by trucks according to averaging period using inputs from Table 3-5.
Table 3-7: Applied Road Dust Emissions Control Factor – Construction Phase

Notes:
(1) Control factor applied for the scenario with the water trucks in operation.
(2) Control factor applied for the scenario without the water trucks available.

3.3.4 Aggregate Crushing Plant
An aggregate crushing plant will be set up at ARA-2 quarry during the first years of construction. Crushing following by screening have the potential to generate dust which emissions were estimated according to the emission factors provided in ECCC (2018) “Pits and Quarries Reporting Guide”. Combined emission factors for crushing and screening without specific dust control measures in place were selected (15 g TPS per tonne of aggregates; 5.5 g PM10/t; and 0.89 g PM2.5/t), even though it is most likely that it will not be the case.
The fugitive dust emission rates (TSP, PM10 and PM2.5) were then derived from the emission factors and aggregate processing rate expected during Year 1 as specified in Table 3-8.

3.3.5 Aggregate Loading and Unloading
Dust emissions from aggregate loading at ARA-2 quarry and unloading along the road during aggregate placement are estimated using the method suggested in the US EPA AP-42 Emission Factor Compendium Series for bulk material handling (US EPA, 2006a).

EF: particulate matter emission factor (g/t transferred)
k: granulometric multiplier (TSP = 0.74; PM10 = 0.35; PM2.5 = 0.053) U: mean wind speed (m/s)
M: moisture content of transferred material (%)
Aggregates, unless they are wetted by precipitations, usually contain small amounts of moisture (less than 2%). A value 1.5% is applied. The mean wind speed (5.6 m/s) was extracted from the meteorological dataset used for air dispersion modelling. No dust control measures are considered. The resulting emission factors are then applied with hourly transfer rates, as specified in Table 3-9 according to the averaging period.
Table 3-9: Input Data for Dust Emissions from Aggregate Loading and Unloading

Note:
(1) Source B3 is placed at multiple locations along the road. Since aggregate placement only occurs during 1 or 2 days at each location, the effective transfer rate needs to be weighed down to 1.5 t/h (applicable at all B3 volumes during the modelled emission period).

3.3.6 Operation of Dozers and Graders
Road construction will require dozers, among other equipment, to place fill materials and aggregates on the road. Graders will also be used to level and compact the aggregates. Both activities will generate dust emissions from their blades.
Three (3) dozers are expected to be used during road construction, especially during aggregate placement activities. Their combined dust emissions were inferred from the method suggested in ECCC (2018) “Pits and Quarries Reporting Guide” taken from the US EPA AP-42 Emission Factor Compendium Series for mining operations (US EPA, 1998).

𝐸𝐸 = 2,6 × 𝑘𝑘 × 𝑠𝑠1,2 × 𝑀𝑀−1,3 × 𝑇𝑇 ÷ 3,6 for TSP and PM2.5 (3-4)
𝐸𝐸 = 0,34 × 𝑠𝑠1,5 × 𝑀𝑀−1,4 × 𝑇𝑇 ÷ 3,6 for PM10 (3-5)
E: particulate matter emission rate (g/s)
k: granulometric multiplier (PMT = 1; PM2.5 = 0,105)
s: silt content in handled material (%)
M: moisture content of handled material (%)
T: fraction of time material is being displaced by the dozer (-)

Applied silt content (fine fraction < 75 µm) is the same as the one used for road emissions from trucking (5.0%) while moisture content is also the same used for aggregate loading and unloading emissions (1.5%). A T value of 0,5 is selected, meaning that the dozer is moving with the blade on the ground half of the time while being idle, moving to another area, or backing the remainder of the time.
One grader will also be in operation which dust-related emissions are calculated using the approach suggested in US EPA (1998) as below:

𝐸𝐸𝐹𝐹 = 11.4 × 𝑘𝑘 × 𝑆𝑆2.5 × 𝑇𝑇 for TSP and PM2.5 (3-6)
𝐸𝐸𝐹𝐹 = 8.7 × 𝑆𝑆2.0 × 𝑇𝑇 for PM10 (3-7)

EF: particulate matter emission factor (g/km)
k: granulometric multiplier (TSP = 1; PM2.5 = 0.031)
S: grading speed (mph)
T: fraction of time material is being displaced by the grader (-)

A grading speed of 6 mph (10 km/h) is selected which typically represents a maximum when heavy blading is undertaken by the grader (which is expected during the construction phase). A T value similar to dozers is also applied (0.5). The resulting emission factors are then multiplied by the distance travelled which is also based on grading speed. Finally, since source B3 is placed at multiple locations along the road (at 300 m intervals), the emission rates for the
1-month and annual averaging periods need to be weighted down since the dozers and grader will be at one location for only 1 or 2 days during the year (Table 3-10).

Table 3-10: Emission Rates Weighting per Averaging Period for Dozers and Graders

3.3.7 Blasting
Some part of the bedrock at ARA-2 pit needs to be dislodged through blasting with explosives. It is expected that 5 blast events will be needed during Year 1. Each blast event will generate a dust plume that was estimated based on ECCC (2018) “Pits and Quarry Emissions Reporting Guide” as follow.
𝐸𝐸𝐹𝐹 = 0,22 × 𝑘𝑘 × 𝐴𝐴1,5 (3-8)

EF: total particulate matter emissions during a blast (g)
k: granulometric multiplier (TSP = 1; PM10 = 0.52; PM2.5 = 0.03)
A: Horizontal blast surface (m2 / blast)

Being instantaneous, the total emissions of PST, PM10 and PM2.5 (in grams) were brought back to one hour (divided by 3,600 seconds) in the model. Meanwhile, the horizontal surface area (5,861 m2) per blast was estimated based on the fact that 125,000 m3 of bedrock needs to be dislodged from a total of 1,500,000 m3 of rock available at the 35 ha ARA-2 pit (350,000 m2 x (125,000 / 1,500,000) / 5 blasts).
Since blasting will occur only occasionally, the emission rates applicable for 24-hour averaging period are weighted down for the other averaging periods, as presented in Table 3-11.
Table 3-11: Input Rates Weighting per Averaging Period for Blasts

3.4 Emission Parameters Summary
Table 3-12 and Table 3-13 summarizes the emission sources included in the model for the construction phase of the Project. It provides an overview of emission parameters and emission rates for NOX (exhaust gas) and TSP
(fugitive dust) applicable to 1-hour, 24-hour, 30-day, and annual averaging periods, where applicable. The emission rates for the other contaminants and other parameters that needs to be specified in the model are available in the summary section of Appendix A. The parameters used for dry depletion on fugitive dust TSP based on the approach defined in Section 2.7 are provided in Table 3-14.
Table 3-12: Summary of Exhaust Gas Emission Sources for the Construction Phase

Table 3-13: Summary of Fugitive Dust Emission Sources for the Construction Phase

Notes:
(1) Combines dust emissions from dozers, graders and aggregates unloading.
(2) Combines dust emissions from the crusher and screener and aggregates transfer on site (loading in trucks).

Table 3-14: Dry Depletion Parameters Applied for Dustfall and TSP Concentration Simulations

3.5 Mitigation Measures
An Air Quality and Dust Control Management Plan will be deployed during construction that will include typical mitigation measures such as:
 the use of water sprays from trucks to increase moisture levels in active areas during dry days (e.g., haul/access roads, temporary soil and aggregate stockpiles),
 the use of environmentally certified equipment (e.g. Tier 4 engines),
 the use of dust suppression systems at quarries,
 truck speed limitations for hauling, including vehicle and heavy equipment movement limitations to designated areas; and
 minimizing idling of vehicles and heavy equipment.

The emission scenario as previously described was first modelled without consideration of specific emission controls, so to verify the impact of the Project in base case conditions. The emission scenario was then re-assessed by considering the following quantifiable control measures that are expected to have most impact on fugitive dust and engine exhausts emissions:
 water-spraying on-road surface mitigating dust uplifting from heavy-duty trucks. The applied particulate emissions control factors were developed in Section 3.3.3.
 the use of at least 80% of mobile and stationary equipment having a Tier 4F engine, when the base scenario only considers Tier 3 engines (Section 3.3.1). The equipment units with Tier 4F engines were selected randomly given the large of number of units that will be required on site (over 50 units; see Table 3-2).
These mitigation measures were applied in the assessment as they would have more significant impact to offset effects under the base case scenario. The Air Quality and Dust Control Management Plan will not limit itself to these measures as there are many other options to mitigate dust uplifting and exhaust emissions. Most of these options like idling minimization, limitation of unnecessary vehicle and heavy equipment movement, and the wetting of soil and aggregate stockpiles during dry days cannot however be properly translated into the dispersion model and so their potential impact is not calculated here.

3.6 Air Dispersion Modelling Results
Air dispersion modelling results for the construction phase are presented in Tables 3-15 and 3-16 for all studied contaminants and in isocontour maps for contaminants which are significantly impacted by the Project relative to applicable AAQC and CAAQS. The tables present the maximum concentration calculated in air (or on ground for dustfall) anywhere along the WSR at 50 m on either side of the road centerline (RCL) based on the 5-year meteorological dataset and without consideration of emission control measures.
Table 3-17 presents the results when integrating the control measures above. The tables present the results for the Project’s contribution alone and with the background concentration from Section 2.5. Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
The results presented in Table 3-18 focus on maximum concentrations calculated at sensitive receptors for contaminants contributed by the Project according to Table 3-15 to Table 3-17 (>50% of applicable standard at 50 m of the RCL). Given the large number of sensitive receptors, only the ones which are closest to the RCL are presented in Table 3-18. It includes existing residences, institutional buildings, and Indigenous culturally sensitive areas. Note that future residences are not analyzed since they will not exist during the construction phase. The results for the other receptors which are lower than the ones presented in Table 3-18 are available in Appendix B for reference.
Given the very large modelling domain, the isocontour plots illustrate the distribution of maximum concentrations of selected contaminants (project contribution + background) for the western segment of the road only (from Webequie to the WB-1 bridge). To do so, the model was re-simulated using a denser array of receptors in this area.

Table 3-15: Maximum Concentrations for CACs Calculated in Air During the Construction Phase (without mitigation measures)

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Maximum concentration calculated at 50 m from the road centerline.
(2) Background concentrations as established in Section 2.5.
(3) The results represent the 1st highest 1-hour concentration and not the 88th highest 1-hour concentration as required from the CAAQS.

Table 3-16:    Maximum Concentrations for Other Contaminants Calculated in Air During the Construction Phase (without mitigation measures)

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Maximum concentration calculated at 50 m from the road centerline.
(2) Background concentrations as established in Section 2.5.

Table 3-17:    Maximum Concentrations for Other Contaminants Calculated in Air During the Construction Phase (with mitigation measures in place)

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Maximum concentration calculated at 50 m from the road centerline.
(2) Background concentrations as established in Section 2.5.

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Closest receptor of this category from the road centerline (RCL) at 1,350 m. Results for other receptors located further away are in Appendix B.
(2) Closest receptor of this category from the RCL at 1,800 m. Results for other receptors located further away are in Appendix B.
(3) Only the results for culturally sensitive receptors located within 400 m of the RCL are presented. Results for other receptors located further away are in Appendix B.

3.6.1 Common Air Contaminants
Construction activities have the potential to create conditions that would exceed the standards for particulate matter (of all size) as well as NO2 for short-term averaging periods (1-hour and 24-hour) outside the ROW. No issues are noted for SO2 and CO which maximum concentrations at 50 m distance from the RCL remain low (<5% of applicable standard; Table 3-15).
When integrating the road dust control measure (use of water trucks), the results do not change significantly (i.e., max of 1,528 g/m3 at 50 m distance for TSP (Table 3-17) vs. 1,597 g/m3 without controls (Table 3-15)), meaning that road emissions are not the predominant source. Dust emissions at the construction site due to bulldozing, road grading and aggregates unloading (source ID B3) are actually the main cause of these high concentrations. As mentioned previously, it is not possible to define the exact combination and space distribution of equipment and activities that will occur at individual sections of the road, and so all potential emissions were combined together in a single source as a simplified and conservative approach. Hence, all three dozers and graders available on site were considered in operation in the same close area which would probably not be the case in reality (or at least there would be some distance between each equipment).
When adding the background concentration, these conditions could also lead to exceedances in TSP and PM10 concentrations up to about 500 m and 800 m distance from the RCL, respectively (Table 3-18 and Appendix B). For PM2.5 concentrations (24-hour average period), it could potentially exceed the standard up to about 250 m from the RCL which therefore results in exceedances for four of the culturally sensitive areas (CHL05, CH14, CHL17, and CHL25).
Based on the emission scenario, NO2 concentrations could also exceed the applicable CAAQS (209% of the 1-h limit value including background concentration) and AAQC (275% of the 24-h limit value including background concentration) at 50 m distance from the RCL in the case where all machinery operates Tier 3 engines (scenario without control measures). When considering the fact that at least 80% of machinery should operate Tier 4 engines, exceedances remain at 50 m distance from the RCL, but at much lower extent (132% of CAAQS instead of 209%; and 128% of AAQC instead of 275%). The NO2 CAAQS could also be exceeded up to 150 m distance from the RCL, which include one culturally sensitive area located within 150 m from the road (Table 3-18). For the NO2 AAQC, no exceedances are noted at 150 m distance and beyond.
The exceedances noted in Table 3-15, Table 3-17 and Table 3-18 relate to standards with a 1-hour or 24-hour averaging period but not for annual standards for which the Project has low impact (<10% of applicable standard). It is tied to the fact that construction activities and associated emissions will not remain at a single location for long periods which greatly dilute the impact of emissions on the annual averages. Similarly, the frequency of exceedances calculated at one location (receptor) for the 1-hour and 24-hour standards would be limited to one or a couple of days over the entire construction phase, as the construction activities move along the road.
Finally, it is important to note that no exceedances were calculated for CACs at existing residences and institutional buildings with and without the background concentrations.
Figure 3.2 to 3.7 provide isocontours plots with regard to the maximum TSP (24-hour), PM10 (24-hour), and NO2
(1-hour and 24-hour) concentrations for the emission scenario with application of mitigation measures. It also shows the PM2.5 (24-hour) and NO2 (1-hour) concentrations compared with the corresponding CAAQS.

3.6.2 Toxic Contaminants
Exceedances were calculated for acrolein (24-hour) and benzene (24-hour) at 50 m distance of the RCL for the emission scenario using emission factors for Tier 3 engines (212% and 141% of the applicable AAQC, respectively including the background concentration). When considering the emission scenario with 80% of Tier 4 engines, exceedance is obtained only for acrolein, at much reduced extent (101% and 80% of applicable AAQC for acrolein and benzene, respectively; Table 3-17). Otherwise, no exceedances were calculated for all toxic contaminants at sensitive receptors, including existing residences, institutional buildings, and culturally sensitive areas (Table 3-18).
This excludes B[a]P (annual period) since the selected background concentration is equal to the AAQC as part of this assessment (Table 3-16). Otherwise, without the background concentration, the maximum B[a]P concentration calculated in air represents 11% of the AAQC at 50 m distance from the RCL and will actually be much lower when considering the scenario with 80% of Tier 4 engines.
Figure 3.8 to 3.11 provide isocontours plots with regard to the maximum acrolein (1-hour and 24-hour), benzene (24-hour), and propionaldehyde (10-minutes) concentrations for the emission scenario with application of mitigation measures.

3.6.3 Dust Deposition
A maximum dust deposition value of 12 g/m2 over 30-days (including background dust deposition) was calculated at 50 m distance from the RCL (corresponding to 166% of the AAQC) without the dust control measure (water trucks on- road). Like for particulate matter concentrations, the impact of water control on the results remains low, bringing the dust deposition value down to 10 g/m2 over 30-days (or 143% of the AAQC). That said, given the depletion effect, dust surficial concentration on ground decreases systematically beyond 50 m from the RCL reaching at maximum 5.4 g/m2 (including background) at 150 m distance. In fact, maximum calculated dustfall at existing residences, institutional buildings, and culturally sensitive areas are 0.49, 0.47, and 3.4 g/m2 over 30-days of deposition, respectively which are lower than the criteria of 7.0 g/m2 representing the accepted threshold in Ontario for soil and vegetation.
Figure 3.12 provides the isocontours plot for dustfall calculated through the depletion of particulate matter emissions.

3.6.4 Eastern Section of the WSR
As mentioned previously, the modelling domain is restricted to the western section of the WSR covering 42 km of the 107 km road. The focus of the assessment and modelling on this area was due to the proximity of Webequie and the fact that a majority of culturally sensitive areas and land uses (including fishing areas, country-food) are located in this portion of the study area for the Project.
That said, there is a culturally sensitive area in the east part of the road that is not covered in the modelling domain (at about chainage 70-71 km from Webequie corresponding to a hunting area at 1,000 m from the WSR at its closest
location). Based on calculated results, TSP and PM10 concentrations are not expected to exceed the respective AAQC at this distance (1,000 m) from the RCL, even when considering the very conservative dust emissions calculations. The same conclusion can be drawn de facto for the other CACs, the toxic contaminants and dust deposition for this particular culturally sensitive area since the impact of road construction activities are expected to be of similar nature along the way albeit most likely some differences with regard to planning of activities along the way to the east terminus of the road.

3.6.5 Ground-Level Ozone
Construction activities are not anticipated to emit ozone (O3) but could still have the potential to add ground-level O3 in air given that NOx and VOCs, which are the precursors to O3 along with sunlight, will be emitted by engines. CAAQS and AAQC exists for O3 (60 ppb (8-hour average) and 80 ppb (1-hour average), respectively) and therefore, it should be examined if the Project could cause air quality problems on that respect. The Baseline Report on air quality established the background O3 concentration at 28 ppb (or 58% of the 8-h AAQC).
According to the Empirical Kinetic Modelling Approach (EKMA) of the US EPA (1983), O3 formation depends greatly on the relative concentration of VOCs (as carbon content; in ppmC) and NOx (NO + NO2 in ppm) in air. It suggests that in the absence of large transport of O3 in the region, a VOC/NOx concentration ratio of about 8:1 would be optimal for generating O3 in air. A ratio that is much lower or much higher than this value should not generate O3, or at least in non- negligible amount (aka VOC-limited and NOx-limited formation). When calculating the ratio of the sum of all 1-hour THC (which is a surrogate to VOC) emission rates with the sum of all 1-hour NOx emission rates from off-road equipment and vehicles, a VOC/NOx ratio lower than 0.1 is obtained. Although all emissions obviously do not occur at the same location together, it outlines the relative input of VOCs and NOx into the atmosphere from the Project’s perspective.
Being in a remote area, the background NOx and VOC concentrations in air are already low and not favourable to O3 formation. For example, in Section 2.5, the background concentration for NO2 was established at 12 ppb (0.012 ppm). When adding all studied VOCs, the background concentration is less than 7 ppbC, although it could be higher since not all potential VOCs in air were studied. All put together, it is predicted that construction activities will not create conditions that would increase the ground-level O3 concentration in ambient air or if it becomes the case, it would be short-lived since the emissions will be diluted in time and space along the road.±

4 Operation Phase
The operation phase of the WSR includes the vehicular traffic on the road as well as maintenance activities during the period generating both exhaust gas emissions and fugitive dust emissions. A permanent MSF will be erected near the WSR with the purpose of storing the equipment and materials used for inspection, maintenance, and repair activities. Activities occurring at the MSF will mainly include equipment maintenance and repair mostly inside garages. Otherwise, the maintenance team will regularly conduct inspections and maintenance work to ensure the road meets the minimum operational standards for roadside safety. Such activities will mainly include:
 Visual patrols and inspections of the road;
 Vegetation management (mowing, brush removal);
 Repair and/or rehabilitation of culverts and bridges at water crossings;
 Repair to road surface and shoulders;
 Dust control, if required;
 Road drainage system maintenance and repairs;
 Access road maintenance;
 Snow clearing;
 Spills and emergency response;
 Waste and excess materials management; and
 Modelled Emission Sources.

The emission sources include the regular daily passages of vehicles mainly from Webequie (less than 500 vehicles) to the eastern terminus of the road where proposed mineral exploration and developments are located and the proposed planned Northern Road Link to the south will connect with the WSR. In addition to vehicular traffic from and to Webequie, the types of vehicles using the road will also include heavy-duty trucks that will be used as part of maintenance activities like visual patrols, snow clearing, and aggregate hauling as part of road repairs. Although the road is expected to be surfaced with asphalt or chipseal, the emission scenario considers an aggregate/gravel-surface as it is expected that part of the road will not be fully surfaced from the start (refer to Section 1.1). As a result, a second source is modelled to capture road grading and maintenance activities, and associated air quality concerns. This represents a conservative approach with regard to dust emissions. The application of asphalt or chip seal would obviously result in lower TSP, PM10 and PM2.5 concentrations in air and dustfall on the ground in the immediate area of the road.
Other air emission sources associated with isolated road maintenance activities such as brush and vegetation removal/control within the ROW, and specific road, culvert, and bridge repairs requiring an excavator, a tractor, and a couple of graders for snow clearing are excluded considering that these activities are unspecific to a single location and will occur infrequently. Other emission sources that are excluded include the following:
 Diesel generator set(s) that will be installed at the MSF; however, the size and location are unknown at this time. The MSF is expected (although not confirmed) to be built near rehabilitated ARA-2 quarry adjacent to an area with no nearby sensitive receptors.
 Crushing and screening activities will occur at the ARA-4 quarry during a typical year in the operation phase for the Project. The impact of quarrying activities at higher production rate is covered in the assessment within the construction phase although at another location, and therefore adverse are anticipated to be minimal and below applicable air quality standards (AAQC and CAAQS). It is also important to note that the ARA-4 quarry is located at more than 2,500 m from the closest culturally sensitive area (refer to Figure 1.2) while receptors located at more than 1,000 m from the RCL did not undergo any AAQC or CAAQS exceedances for the construction phase.

4.1 Air Dispersion Modelling Approach
The emission scenario is composed of a linear volume source within the modelling domain between Webequie and the intersection of the WSR with ARA-4 quarry access road. Although emissions will also occur on the eastern part of the WSR, the concentration profile from road center will be very similar. The exhaust gas from vehicles and fugitive dust emissions from the road and grading activities were modelled separately since they have different emission parameters. Also, for simplification, the fugitive dust emissions from both sources were combined in a single source.
Results were calculated based on a scenario without particular emission control measures and a similar scenario with control measures which, for the operation phase, concern fugitive road dust control with a water truck.

4.2 Emission Rate Calculations
4.2.1 Vehicular Traffic (road engines)
Considering the low population density and the intended purpose of the WSR, a daily traffic of less than 500 vehicles is projected. It is expected that traffic will comprise primarily of light to medium personal vehicles, but also commercial vehicles and heavier trucks carrying industrial (mining) supplies. This category also includes the road maintenance vehicles. The WSR traffic operations will not include mineral ore or mine product hauling/transport. That said, the distribution per vehicle category (light vehicles, light trucks, and heavy trucks using either gasoline or diesel) is unspecified.
Table 4-1 provides an overview of parameters used to estimate the travelling distances expected from vehicles. Other than a maximum daily traffic of 500, the monthly and annual number of passages are based on an average daily traffic volume of 350 vehicles that will occur mainly during daytime.
Table 4-1: Vehicular Traffic Scenario Considered in the Model

Total distances are combined with CACs emission factors (TSP, NOx, CO, SO2, THC) applicable to on-road vehicles (g/km). They were obtained from the US BTS (2023) compiling average emission factors according to the MOVES4 model by vehicle type and year of operation. The emission factors presented in Table 4-2 relate to an average vehicle fleet operated in 2020 (representing conservative values as average emission factors in future years tend to decrease). The emission factors for the other contaminants covered in this assessment were obtained as follow:
 PM10: Equivalent to TSP
 PM2.5: Equivalent to 92% of TSP
 DPM: Equivalent to PM2.5
 SO2: Estimated based on the energy consumption efficiency provided in US BTS (2023) for the year 2020 using fuel containing 15 ppm of sulphur.

 VOCs: Calculated based on the THC emission factor multiplied by the fraction of the COV in THC. The fractions were inferred from data provided in Table 3-5 for vehicles constructed in 2017+ (ratio of contaminant in total VOCs) and a ratio of 1.285 COV/THC from US EPA (2020) technical document “Air Toxic Emissions from On-Road Vehicles in MOVES3”.
 B[a]P: Calculated based on the PM2.5 emission factor multiplied by the fraction of B[a]P in PM2.5 which is inferred from data provided in Table 3-5 for vehicles construction in 2017+ (ratio of PAH in PM2.5) from US EPA (2020) technical document “Air Toxic Emissions from On-Road Vehicles in MOVES3”.
Table 4-2: Emission Factors for Vehicles Exhaust Gases

Notes:
(1) Maximum emission factor from US BTS (2023) from either light-duty trucks, light-duty vehicles or light-duty trucks using diesel or light-duty trucks or vehicles using gasoline.
(2) Average of emission factors for diesel heavy-duty and light-duty trucks which are the most common categories expected on the road.

4.2.2 Vehicular Traffic Dust Emissions
Dust emissions from the passage of trucks were estimated according to the method suggested in the US EPA AP-42 Emission Factors Compendium Series for unpaved roads (US EPA, 2006a) as presented in Section 3.3.3. Road silt (fine fraction < 75 µm) is set to 6.0% which represents 60% of the maximum allowed amount of fine aggregates in freshly crushed Granular A from quarried materials composing the road surface. Vehicle speed and road surface moisture are set to 50 mph (80 km/h) and 1.5%, respectively, the latter due to the fact that aggregates usually contain small amounts of moisture (1 to 2%) in dry conditions.
Dust control with water trucks will be carried out by WSR maintenance crews. The applied control factors were derived according to ECCC (2024) “Road dust emissions from unpaved surfaces: Guide to reporting” which considers overall control factors on a monthly and annual basis adjusted according to the number of days with precipitations greater than
0.2 mm and/or days with freezing conditions (maximum daily temperature below the freezing point) with 100% control for both instances.

Table 4-3 summarizes the control factors per time of the year and averaging period. Climate normals from Pickle Lake were used to establish overall control factors (being the closest location with data to the Project). It also shows the control factors considered for the scenario without control measures applied for the May-November period. During winter, the same natural control efficiency is applied. The fugitive dust emission rates (TSP, PM10 and PM2.5) are then derived from the emission factors as above (g/km) and the total distance travelled by vehicles according to the averaging period (Table 4-1).
Table 4-3: Applied Road Dust Emissions Control Factor – Operation Phase

Table 4-3:      Applied Road Dust Emissions Control Factor – Operation Phase

Notes:
(1) Control factor applied for the scenario with control measures.
(2) Control factor applied for the scenario without control measures.

4.2.3 Grading Dust Emissions
It is expected that graders will be used for regular road maintenance during a typical year generating dust emissions from their blades. The same calculation approach as described in Section 3.3.6 applies. A grading speed of 9.5 mph (15 km/h) is selected which typically represents a maximum when doing road maintenance with the blade always on the ground (T = 1). The resulting emission factors are then multiplied by the distance travelled which is also based on grading speed. Table 4-4 finally presents the emission rate weights applied to the emission factor depending on averaging period.
Table 4-4: Emission Rates Weighting per Averaging Period for Graders during Operation Phase

4.3 Emission Parameters Summary
Table 4-5 and Table 4-6 summarizes the emission sources included in the model for the operation phase of the Project. It provides an overview of emission parameters and emission rates for NOX (exhaust gas) and TSP (fugitive dust) applicable to 1-hour, 24-hour, 30-day, and annual averaging periods, where applicable. The emission rates for the other contaminants and other parameters that needs to be specified in the model are available in the summary section of Appendix A. The parameters used for dry depletion on fugitive dust TSP are provided in Table 4-7.
Table 4-5: Summary of Exhaust Gas Emission Sources for the Operation Phase

Table 4-6: Summary of Fugitive Dust Emission Sources for the Operation Phase

Table 4-7: Dry Depletion Parameters Applied for Dustfall and TSP Concentration Simulations

4.4 Mitigation Measures
While it is impossible to have a direct control on emissions from vehicle engines, it is possible to work on dust emissions from the road surface. Considering that part of the road will not be fully surfaced with asphalt or chip seal from the start, the maintenance crew will have available a water truck that will spray water over the gravel-surface road from May to November, when needed. As a result, the emission scenario described above was modelled first without and then with this control measure in place. The applicable control factors were developed in Section 4.3. When the road surface will be fully surfaced with asphalt or chipseal, it will result in much lower TSP, PM10 and PM2.5 concentrations in air and dustfall on the ground in the immediate area of the road. The impact of flexible pavements on particulate emissions was not calculated as part of this study but will be discussed and put into perspective with current results in Section 5.

bridge repairs was excluded from dispersion modelling since these activities are unspecific to a single location and will occur infrequently. Moreover, these units that should include, according to current projections, two excavators, two rubber tire loaders, two tractors, and three graders will be purchased as new and will be certified Tier 4F which greatly limits NOx, VOCs and fine particulate emissions from exhaust pipes.

4.5 Air Dispersion Modelling Results
Air dispersion modelling results for the operation phase are presented in Table 4-8 and Table 4-9 for all studied contaminants and in isocontour maps for contaminants which are significantly impacted by the Project relative to applicable AAQC and CAAQS. The tables present the maximum concentration calculated in air (or on ground for dustfall) anywhere along the WSR at 50 m on either side of the road centerline (RCL) based on the 5-year meteorological dataset and without consideration of the emission control measures.
Table 4-10 presents the results when integrating the control measures which applies to particulate matter and dustfall only. This table also presents the results for the Project’s contribution alone and with the background concentration from Section 2.5. Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
The results presented in Table 4-11 focus on maximum concentrations calculated at sensitive receptors for contaminants which are meaningfully impacted by the Project according to Table 4-8 to 4-10 (>5% of applicable standard at 50 m of the RCL). Given the large number of sensitive receptors, only the ones which are closest to the RCL are presented in Table 4-11. It includes existing residences, institutional buildings, culturally sensitive areas, and future residence plots. The results for the other receptors which are lower than the ones presented in Table 4-11 are available in Appendix B for reference.
Given the very large modelling domain, the isocontour plots illustrate the distribution of total concentrations of selected contaminants (project contribution + background) for the western segment of the road only (from Webequie to the WB-1 bridge). To do so, the model was re-simulated using a denser array of receptors in this area.
Table 4-8: Maximum Concentrations for CACs Calculated in Air During the Operation Phase (without dust control)

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Maximum concentration calculated at 50 m from the road centerline.
(2) Background concentrations as established in Section 2.5.
(3) The results represent the 1st highest 1-hour concentration and not the 88th highest 1-hour concentration as required from the CAAQS.

Table 4-9: Maximum Concentrations for Other Contaminants Calculated in Air During the Operation Phase (without dust control)

Notes:
(1) Maximum concentration calculated at 50 m from the road centerline.
(2) Background concentrations as established in Section 2.5.

Table 4-11: Maximum Concentration for Contaminants Calculated in Air in Areas of Interest During the Operation Phase (with dust control)

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Closest receptor of this category from the road centerline (RCL) at 1,350 m. Results for other receptors located further away are in Appendix B.
(2) Closest receptor of this category from the RCL at 1,800 m. Results for other receptors located further away are in Appendix B.
(3) Only the results for culturally sensitive receptors located within 400 m of the RCL are presented. Results for other receptors located further away are in Appendix B.
(4) Only the results for the receptors closest to the RCL for each future residence areas are provided.

4.5.1 Common Air Contaminants
Daily vehicular traffic and maintenance grading activities on the road will generate dust emissions mostly from the road surface. Maximum expected daily traffic on the road (less than 500 vehicles), may lead to TSP and PM10 concentrations based on 24-hour average that would exceed the applicable AAQC if no dust control measures are in place (Table 4-8). The maintenance crew will have a water-spraying truck readily available to be used when needed, especially during dry summer months. Note that TSP, PM10 and PM2.5 in air comes almost exclusively from road dust emissions and less from exhaust gases (representing <1% of particulates in this scenario).
When considering a low 30% control factor on emissions during these periods (refer to Section 4.3), the maximum TSP concentration would decrease enough to fall below the corresponding AAQC at 50 m distance from the RCL and beyond. The PM10 (24-hour) AAQC could still be exceeded by 39% (Table 4-10), although there remains a margin to improve the control level by increasing the number of passages during days with high dust uplift and dispersion potential that would most likely mitigate such exceedances. That said, when looking at sensitive receptors, PM10 concentrations calculated in air do not exceed the AAQC. In fact, there are no exceedances noted at these receptors for

all CACs. The road traffic is not expected to increase gaseous CACs (NO2, SO2, and CO including PM2.5) concentrations higher than 5% of the corresponding AAQC or CAAQS at 50 m distance from the RCL. This percentage is obviously lower at greater distances where sensitive receptors are located at different distances. When adding background concentrations, the results remained below air quality standards.
Figure 4.1 to 4.4 provides isocontour plots with regard to the maximum TSP (24-hour), PM10 (24-hour), PM2.5 (24-hour), and NO2 (24-hour) concentrations for the emission scenario including mitigation measures. Although showing low concentrations, the isocontour plot for NO2 is provided to illustrate the concentration profile of contaminants from vehicles exhaust pipes along the road.

4.5.2 Toxic Contaminants
Based on maximum expected traffic, concentrations of VOCs at 50 m distance from the RCL will remain very low (<1% of the applicable AAQC) and are therefore not a concern for sensitive receptors with regard to air quality (Table 4-9). No exceedances were calculated with or without background concentration at existing residences,
institutional buildings, culturally sensitive areas, and future residence plots except for benzo(a)pyrene which background concentration already represents 100% of the AAQC (Table 4-10). That said, this background concentration was inferred from a monitoring station in Simcoe, Ontario, which is not located in a remote area such as Webequie but is considered the most representative from all available data located in a non-urban setting that are not impacted by any significant emission sources nearby. Webequie has however a much smaller population than Simcoe, and there is little (e.g., temporary or short-term land use for traditional activities) or no human interaction along the WSR route, and potential emission sources are more limited. As such, the average B[a]P concentrations are expected to be significantly lower than those observed in Simcoe and thus, the background concentration may be over-estimated. However, exceedances may be still possible in areas during winter with wood burning from remote communities in the region and meteorological conditions offering poor dispersion, or in the event of wildfires.

4.5.3 Dust Deposition
A maximum dust deposition value of 8.4 g/m2 over 30-days (including background dust deposition) was calculated at 50 m of the RCL (correspond to 120% of the AAQC) without the dust control measure (water trucks). Given the depletion effect, dust surficial concentration decreases systematically outside 50 m reaching at maximum, 2.7 g/m2 at 150 m distance for example.
With the control measure in place, the results show a slightly improved maximum dust deposition value of 6.0 g/m2 over 30-days (including background dust deposition) at 50 m of the RCL (correspond to 85% of the AAQC). Maximum calculated dustfall concentrations at existing residences, institutional buildings, culturally sensitive areas, and future residences plots are 0.50, 0.48, 3.8 and 4.0 g/m2 over 30-days of deposition, respectively which are lower than the criteria of 7.0 g/m2 representing the accepted threshold in Ontario for soil and vegetation.
Dustfall calculations from particulate matter emissions are also illustrated in Figure 4.5.

4.5.4 Eastern Section of WSR
As mentioned previously, the modelling domain is restricted to the western section of the WSR covering 42 km of the 107 km road. The focus of the assessment and modelling on this area was due to the proximity of Webequie and the fact that a majority of culturally sensitive areas and land uses (including fishing areas, country-food) are located in this portion of the study area for the Project.

For the eastern section of the WSR, a culturally sensitive area is located in the eastern side (at about chain 70-71 km from Webequie) corresponding to a hunting area at 1,000 m from the WSR at its closest location. Given that maximum concentrations calculated in air do not exceed the corresponding standard at any of the sensitive receptors, it is safe to assume the same conclusion for this receptor (except for B[a]P (annual) for the reasons explained above). In fact, given the absence of collector or distributor roads along the WSR (except for the future proposed Northern Road Link to the south that will link the WSR at its eastern terminus), the same traffic load is to be expected during an hour, day, or a year whether on the western or eastern section of the road. The impact of road dust and vehicular emissions are therefore expected to be of similar for the eastern and western section albeit minor differences due to road alignment and local topography.

4.5.5 Ground-Level Ozone
The vehicles will not emit O3 but could still have the potential to add ground-level O3 in air given that NOx and VOCs, which are the precursors to O3 along with sunlight, will be emitted. CAAQS and AAQC exists for O3 (60 ppb (8-hour average) and 80 ppb (1-hour average), respectively) and therefore, should be examined if it could cause air quality problems. The Baseline Report on air quality established the background O3 concentration at 28 ppb.
According to the EKMA of the US EPA (1983), O3 formation depends greatly on the relative concentration of the VOCs (as carbon content; in ppmC) and NOx (NO + NO2 in ppm) in air. It suggests that, in the absence of large transport of O3 in the region, the VOC/NOx concentration ratio of about 8:1 would be optimal for generating O3 in air. A ratio that is much lower or much higher than this value should not generate O3, or at least in non-negligible amount (aka VOC- limited and NOx-limited formation). When considering the THC (which is a surrogate to VOC) and NOx emission rates from vehicles on the road, a VOC/NOx ratio of 0.065 is obtained.
In a remote area where the proposed WSR is located, the background NOx and VOC concentrations in air are already low and not favourable to O3 formation. For example, in Section 2.5, the background concentration for NO2 was established at 12 ppb (0.012 ppm). When adding all studied VOCs, the background concentration is less than 7 ppbC, although it could be higher since not all potential VOCs in air were studied. Collectively, it is predicted that vehicular traffic will not create conditions that would increase the ground-level O3 concentration in ambient air.

5 Uncertainty Analysis
5.1 Project Data
The quantification of air emissions preferably requires detailed understandings of the operation activities that would generate air contaminants. For the construction phase, a wide array of fugitive dust and exhaust emission sources is to be expected given the endeavour at hand. A large portion of input data were inferred from the information prepared by Sigfusson Northern Ltd. that provided a preliminary plan of activities during construction and a list of equipment and materials needed to complete the work. This construction planning information provided a good basis to develop an emission scenario, but the level of details remains insufficient to calculate emission rates with a high level of certainty for the following reasons:
 The construction plan was based on Sigfusson’s experience but will not necessarily translate to the actual reality as the selected constructor(s) may have a different approach and details on-road design may evolve.
 The construction plan provides broad periods for each activity without going to the day-to-day planning. It is therefore difficult to establish representative conservative emission rates for short-term (1-hour and 24-hour) averaging periods as this can widely change during road construction and day-to-day planning.
For the operation phase, the emission sources are limited to vehicular traffic and road grading and maintenance activities in the case of a gravel road surface. Required data is mostly limited to the traffic volume, grading frequency, and type of vehicles on the road. The latter is probably the most uncertain input but in general the emission rates from these data are considered representative but also conservative.

5.2 Emissions Estimations
With the high number of diesel engines during construction, the emission factors are considered representative, but also conservative given that the US EPA MOVES emission factors represent maximum standards to achieve. For this assessment, it was considered that 80% of all nonroad equipment brought to site will be certified Tier 4F, which is estimated to represent an average of the ratio of Tier 4F machinery currently available by constructors. It is however possible that this proportion will be higher in reality when construction starts. Some uncertainties therefore remain in that respect. That said, a scenario using only Tier 3 engines was also presented to demonstrate such impact.
For road vehicles, the emission factors developed by the US BTS are based on US EPA MOVES which is the standard model in that field. Some uncertainties can be attributed to these calculations considering that the exact type, size, and age distribution of vehicles that can have an impact on emission factors are undetermined. The use of an average emission factor specific to a fleet of vehicles may create a certain bias towards the reality, that nevertheless is not considered to be -significant for the Project (given the large number of vehicles during construction and operation).
The emission rates with the highest degree of uncertainties are the fugitive dust emissions, whether during the construction or the operation phases. They were estimated based on some project characteristics and emission factors from the AP-42 Compendium for roads and other construction activities. These methods are based on empirical relationships establishing an average correlation between the emission factor and the properties of the bulk material or the road surface (silt content, humidity, etc.). In absence of data specific to the project site, these methods can be qualified as approximative and provide an order of magnitude emission rate, rather than a more precise estimate.

5.3 Emissions Scenarios
Some premises were considered in order to develop emission scenarios that represent, in most likelihood, worst-case situations based on the Project information available at this time. For example, the construction emission scenario:
 Was based on the construction year with highest activities and material movement (Year 1) according to Sigfusson’s construction planning.
 Applies emission rates at all hours during the modelled emission period.
 Averages the emission rates when dealing with 24-hour, monthly and annual averaging periods.
 Uses the same emission source volume distributed at 300 m distance to verify short-term nearby concentrations at all locations along the road. When taken altogether, it has the potential to over-estimate the concentration at a further distance due to the interactions of adjacent volumes that are modelled as emitting simultaneously when it will not be the case.
The hourly and daily variability of emissions for each activity during construction is obviously complex and cannot be integrated in a dispersion model. It is why typical emission rates are applied at all hours of the day even though there could be variations within a day and between days. Based on information at this time when preparing this assessment, a worst-case scenario was developed meaning that it should, in most likelihood, not be attainted in reality.

5.4 Dispersion Model
All models integrate various phenomena affecting the physical transport and dispersion of contaminants in air. All models can under-estimate or over-estimate these phenomena, but a good model is expected to be representative of reality most of the time. The AERMOD model was developed from a regulatory standpoint to demonstrate the compliance of air quality standards for industrial projects. The US EPA therefore prefer a model that does not
under-estimate the air concentrations rather than having a precise model, but that could still sometimes under-estimate the reality. From its development, AERMOD is considered conservative and so, it may have the tendency to
over-estimate the air concentrations. The reliability of AERMOD is also better to estimate average concentrations over long periods than short-term concentrations.
That said, the uncertainty of a dispersion study is less caused by AERMOD performance or accuracy but more about the preciseness of input data like meteorological data, modelled phenomena, and information about the emission rates. With the objective to verify the compliance of Ontario’s AAQC and Canadian CAAQS at all times, several conservative assumptions were considered which add to the conservative nature of AERMOD:
 The impact of precipitations on the mitigation of fugitive TSP and PM10 emissions was neglected, as well wet depletion. This hypothesis tends to create an overestimation of TSP and PM10 average annual concentrations or the frequency of elevated hourly and daily concentrations.
 The addition of elevated background concentrations with infrequent maximum concentrations calculated by the model, without knowing if it will occur simultaneously.
 The calculation of maximum hourly and daily concentrations supposes that all sources that can operate intermittently (i.e., dozers not required during a specific period) emit continuously altogether. This approach may generate concentration over-estimations as well as increasing the frequency of elevated daily and hourly concentrations.
The AERMOD model does not integrate the impact of vegetation on dispersion. Considering that large sections of the WSR is surrounded by the forests, their presence will physically alter the dispersion of air contaminants and especially particulate matter at a level that is impossible to predict.

Finally, with regard to dust deposition, the particulate size classes distribution based on AP-42 emission factors remain approximative, especially for particulates subject to deposition (> 10 µm), which introduces additional uncertainties with regard to estimations of particulate matter in air and for which the actual bias (overestimation or underestimation) is undetermined.

5.5 Meteorological Dataset
A complete meteorological dataset based on actual measurements from the Webequie region is not available. The closest existing meteorological station is in Lansdowne House at about 100 km south of Webequie and with incomplete data availability over a 5-year period. The dataset developed by the MECP based on the International Falls station data using land characteristics for northern Ontario (forest) was used. Although its representativeness of Webequie’s condition can be uncertain, it is important to note that the Project footprint is extensive with varying land covers
(forest, peatland, water bodies in the vicinity) that could result in varying local meteorological conditions. There are therefore implied uncertainties by applying a single dataset. The International Falls dataset therefore represents the “best available” dataset providing expected air dispersion tendencies.

5.6 Background Concentrations
Background concentrations were added to the model results. Their purpose is to characterize the current air quality conditions which more or less represent the impact of local / regional emission sources unrelated to the Project. This approach tends to generate conservative results considering that:
 The selected background concentration which represents elevated and uncommon conditions is added to the maximum modelled concentration, without knowing if both situations occur simultaneously.
 With the exception of PM2.5, no readings characterizing the air quality along the WSR route are available. Hence, the majority of background concentrations were derived from measurements at monitoring stations located in remote areas in Canada that can be considered somewhat representative of the actual conditions in the region. Uncertainties will always remain given that the sources of emissions that would impact the readings at these monitoring stations are unknown and could still be different from what is currently occurring in the Webequie area. That said, given the absence of anthropogenic emission sources along the road outside Webequie, the selected background concentrations remain in our opinion conservative.

6 Description of Potential Effects and Interactions
The objective of an air quality assessment is to verify how the Project would impact the ambient air quality around the road and near supportive infrastructure and if there is risk of exceeding a CAAQS or AAQC establishing thresholds against potential health effects and to a minor extent against odour, visibility and vegetation issues. Studied contaminants include the CACs (nitrogen dioxide (NO2), carbon monoxide (CO), sulphur dioxide (SO2), TSP, as well as particulates inferior to 10 µm (PM10) and inferior to 2.5 µm (PM2.5)), ten (10) VOCs including carbonyls (i.e., formaldehyde) and aromatic compounds (i.e., benzene), and benzo(a)pyrene as a surrogate to PAHs. The impact of the Project on dustfall (in g/m2 over 30-days) was also assessed which is represented by an AAQC threshold against dust soiling on the ground and vegetation. PM2.5 emissions from exhaust pipes were also modelled separately from total PM2.5, as DPM, since it is recognized to be carcinogenic with the potential of long-term impact. Finally, no metals were included in the assessment as there are no information about their content in native soil and aggregates that will be handled on site.
These contaminants would come essentially from the combustion of diesel fuel or gasoline from land mobile and stationary equipment, heavy-duty trucks and light-duty vehicles during the construction and operation phases of the Project, and from dust uplifting mostly from vehicular traffic on the road and the handling of aggregates and other earth materials during construction.
The verification of potential exceedance of CAAQS or Ontario AAQC was carried using atmospheric dispersion modelling based on the requirements of the Atmospheric Dispersion Modelling Guide for Ontario from the MECP which designate the AERMOD advanced Gaussian-type steady-state plume model as the preferred model for dispersion studies at the close or local scale (< 50 km). Given the long road distance, the modelling domain was restricted within an area of about 30 km by 30 km that covers 40.5 km of the 107 km road from the community of Webequie to the point on the road where it intersects with the ARA-4 aggregate pit access road. This modelling domain was selected to focus on the impacts within a corridor along the road but also on sensitive receptors (i.e., residences, institutional buildings, and culturally sensitive areas) that are more sizeable in this area.
The receptors, or points of impingement, for contaminant concentrations in ambient air, were arranged at 50 m and 150 m distance from the road centreline and at every 100 m on either side along the road. This configuration provides means to generate lateral concentration profile within a distance of 150 m from the road centerline where the bulk of emissions will occur. Discrete receptors were also placed at the air sensitive locations in the area including:
 Twenty-four (24) existing residences or group of residences including mostly homes within the community of Webequie.
 Six (6) institutional buildings including two schools, a nursing station, a church, a community building, and business center.
 Twenty-one locations in culturally sensitive areas including spiritual or sacred spaces for members of the Webequie First Nation and other Indigenous communities and/or stakeholders and locations important for harvesting country foods or hunting.
 Sixty-six (66) locations for future residences (RPF) per the Webequie First Nation On-Reserve Land Use Plan of 2019 distributed amongst four areas (Site A; Site West; Site C and Site D).

6.1 Construction Phase
The construction of the WSR will be conducted all-year round over an approximately 60-month period. It will consist of two distinct segments, one of 51 km from Webequie running south-easterly and then of 56 km running east until it terminates near the McFaulds Lake area. The first segment (western half of the WSR) resting mostly over mineral soil will be cleared of all vegetation within the 35 m ROW for the road to accommodate the two-lane all-season road.
Shoulders, ditches (as enhanced grass swales) and berms of stripped organic materials on the outside will also be shaped along this segment. Cut and fill earthworks will be needed to adjust the vertical alignment by either lowering or raising the existing grades. An underlying layer of aggregates and a surface layer of crushed stone will then be conveyed by trucks from a nearby quarry and compacted on site by heavy machinery. A layer of chip seal or asphalt will be also added onto the surface.
The eastern segment of the WSR being located within the Hudson Bay Lowlands Ecozone is composed mostly of peatland (muskeg) having a depth of 2-4 m of waterlogged organic soil, which represents poor to very poor conditions for building a road. A floating road design is being recommended by adding an underlying layer of aggregates
(along with geogrids) that will compress the peat resulting in settlement and consolidation. A surface layer of crushed stone will be added to complete the road that is expected to lay 1.2 m above the surrounding lowland areas. Cross- culverts will be integrated within the road structure at regular intervals to ensure that the hydraulic conductivity of the peatlands is maintained. Hence, the construction activities that could potentially impact nearby air quality will include:
 Vegetation clearing, grubbing and disposal.
 Earth stripping along the ROW, the aggregate pits, and the access road.
 Aggregate production (hole drilling, blasting, rock conveyance, crushing, screening, diesel generators and supporting mobile loaders) including hauling to site.
 Road construction including grading, aggregate placement, ditching, geotextile installation, and ditch seeding.
 Chip seal or asphalt placement on the road.
 Construction of steel-concrete bridges that will include a substructure composed of a foundation, abutments and piers supporting the superstructure consisting of steel plate girders, the deck and side barriers with railings. Natural revegetation, seeding and/or planting will be done on and around the embankments once the bridge is completed.
 Installation of major culverts crossing minor watercourses.
 Construction of buildings and storage areas at the MSF.
 Progressive rehabilitation work along the WSR, the ARA-2 quarry and the worker camps when construction work is completed.
 Maintenance of environmental structures / measures (e.g., erosion and sediment control measures), including drainage management features on access roads.
A preliminary plan of activities during the 60-month construction period, including a list of equipment and materials needed to complete the work, was developed. Based on this plan, the first year of construction comes up as the year that should see the greatest number of mobile equipment on site and was selected as basis to assess the potential impact of construction activities on ambient air during the construction phase using air dispersion modelling. Moreover, the majority of activities during Year 1 will be focused between the western terminus (Webequie) and the ARA-2 quarry which is close to the WC-3 water crossing, down to the access road/WSR intersection. This area regroups the great majority of sensitive receptors described above.
Table 6-1 summarizes the construction activities along with the number of equipment and emission sources expected during the first year of construction. The emission rates (g/s) for each contaminant were estimated using for the most part the input data provided in the preliminary construction plan in recognized calculation methods from ECCC or the US EPA with regard to exhaust gas emissions and dust release from road surfaces, aggregate loading/unloading,

dozing, grading, aggregate crushing and blasting. The resulting emission rates were also applied in accordance with the monthly and daily schedule from the preliminary construction plan.
The impact of Year 2 to 5 activities during the construction phase was not specifically assessed as they involve the same emission sources as modelled for Year 1 only at different locations and different extents (i.e., varying number of trucks, different number of equipment to carry out the work). Since the emissions are limited along the WSR 35-m wide ROW, the concentrations in air will be of similar profile whether being on the western or eastern portion of the road.
Table 6-1: Overview of Activities and Emission Sources during the First Year of Construction
Activity Equipment Emission Sources Emission Location

A majority of emission sources will not be static and will move along the WSR during the construction phase. In order to verify the air quality impact of road construction activities, an approach combining emission rates from all equipment and activities that could occur within a specific area (as a volume source) was considered. The intent was to mimic this same volume along the road to verify the potential impact of these activities at all locations. For example, the exhaust gas emissions of all equipment expected during “clearing and grubbing” was combined within a single source and positioned at several locations (300 m interval). This approach was applied for emissions that can occur at different locations (stripping and grading, ditching, geotextile installation, and aggregate placement from Table 6-1). Otherwise, a single volume emission source is applied for fixed locations associated with aggregate production, culvert installation and bridge construction.

6.1.1 Potential Impacts on Ambient Air
Air dispersion modelling of a conservative emission scenario representing the activities expected during the first year of road construction have provided the following outcomes which include the addition of background concentrations representative of the region as defined in Section 2.5. The following results do not consider any specific mitigation measures. The percentages in bold represent the maximum calculated concentration in air including background concentration relative to the applicable AAQC or CAAQS.
 Compliance of SO2, CO, and all toxic contaminants (except for 24-hour acrolein (212%), 24-hour benzene (141%), and 24-hour B[a]P (111%)) concentrations at 50 m distance from the road centerline and beyond. The exceedance for 24-hour B[a]P (as surrogate to PAHs) is obtained because the background concentration was set equal to the applicable AAQC. Therefore, the Project would only add a maximum of 11% of the AAQC at 50 m distance. These results were obtained by considering that all mobile equipment is certified Tier 3.
 Potential exceedance of AAQC and CAAQS related to particulate matter (as below), considering that all dust generating sources during road construction (dozers, graders, material unloading, trucking) are occurring at a single location. This represent a worst-case situation given that, in most likelihood, the equipment operating during a day will be more distributed along the road than confined into a small area. These potential exceedances would also occur for a short period (i.e., 1-2 days) at each receptor given that the emission sources will be moving as road construction progresses.
 Potential exceedance of 24-hour TSP AAQC up to about 500 m from the road centerline (depending on the road location) which comprises thirteen (13) culturally sensitive areas.
 Potential exceedance of 24-hour PM10 AAQC up to about 900 m from the road centerline (depending on the road location) which comprises the majority of culturally sensitive areas.
 Potential exceedance of 24-hour PM2.5 AAQC/CAAQS up to about 300 m from the road centerline (depending on the road location) which comprises five (5) culturally sensitive areas.
 A maximum dust deposition of 12 g/m2 over 30-days was calculated at 50 m distance from the road centerline corresponding to 166% of the AAQC (7 g/m2) without road dust control with water trucks. At 150 m distance, the maximum dust deposition falls to 5.9 g/m2. In fact, maximum calculated dustfall at existing residences, institutional buildings, and culturally sensitive areas are 0.53, 0.50, and 4.6 g/m2 over 30-days of deposition, respectively. No exceedances are calculated at all sensitive receptors for the case without road dust controls.
 Potential exceedance of 1-hour NO2 CAAQS up to 600 m from the road centerline which comprise fifteen (15) culturally sensitive areas, that is when 100% of the machinery brought to site uses Tier 3 engines. No exceedances were calculated at 50 m distance and beyond for the corresponding AAQC while the maximum 1-hour NO2 concentration at this distance exceeds the CAAQS by 232%.
 Potential exceedance of 24-hour NO2 AAQC (275%) at 50 m distance from the road centerline but no exceedances noted at 150 m distance and for culturally sensitive areas.
 Compliance with all long-term AAQC and CAAQS (annual averaging period). It is tied to the fact that construction activities and associated emissions will not remain at a single location for long periods which greatly dilute the impact of emissions on the annual averages.
 Construction activities will not create conditions that would increase ground-level O3 concentration due to already low NOx and VOC concentrations in the remote area or if it becomes the case, it would be short-lived since the emissions will be diluted in time and space along the road.
Although potential exceedances of TSP, PM10, PM2.5, acrolein, benzene, B[a]P, NO2, and dustfall are a possibility outside the road’s ROW during construction, it is worth noting that no exceedances were calculated at existing residences and institutional buildings in the Webequie area. Meanwhile, exceedances will remain a possibility with regard to TSP (AAQC), PM10 (AAQC), PM2.5 (AAQC and CAAQS 24-hour averaging period), and NO2 (CAAQS 1-hour averaging period) concentrations in air for the closest culturally sensitive areas, most likely for a limited period of time at

each location during the projected five-year construction phase. No AAQC exceedances were however calculated with regard to dustfall for these areas.
These results were obtained using a conservative emission scenario that does not apply specific mitigation measures. The quantifiable impacts of such measures are discussed in Section 7.1.

6.2 Operation Phase
The operation phase of the WSR includes the vehicular traffic on the road as well as maintenance activities generating both exhaust gas emissions and fugitive dust emissions. The emission sources include the regular daily passages of vehicles mainly from Webequie (less than 500 vehicles) to the eastern terminus of the road. In addition to vehicular traffic from and to Webequie, the types of vehicles using the road will also include heavy-duty trucks that will be used as part of maintenance activities like visual patrols, snow clearing, and aggregate hauling as part of road repairs. Although the road is expected to be surfaced with asphalt or chipseal, the emission scenario considers an aggregate/gravel- surface as it is expected that part of the road will not be fully surfaced from the start. As a result, a second source was modelled to capture road grading and maintenance activities, and associated air quality concerns.
Other air emission sources associated with isolated road maintenance activities such as brush and vegetation removal/control, and specific road, culvert, and bridge repairs requiring an excavator, a tractor, and a couple of graders are excluded considering that these activities are unspecific to a single location and will occur infrequently. The emission scenario was composed of a linear volume source within the modelling domain between Webequie and the intersection of the WSR with ARA-4 quarry access road. Although emissions will also occur on the eastern part of the WSR, the concentration profile from road center will be very similar.

6.2.1 Potential Impacts on Ambient Air
The operation phase associated with the WSR Project includes mainly the dust and exhaust gas emissions from expected traffic on the road as well as road grading during maintenance work. Air dispersion modelling of an emission scenario from these sources on an annual basis provided the following results which include the addition of background concentrations representative of the region as defined in Section 2.5. The following results do not consider any specific mitigation measures. The percentages in bold represent the maximum calculated concentration in air including background concentration relative to the applicable AAQC or CAAQS.
 Exceedance of TSP (104%) and PM10 (155%) concentrations in air with regard to the AAQC at 50 m distance from the road centerline (outside the ROW). Potential exceedance of PM10 concentrations were also calculated at one culturally sensitive area (108%) and one future residence plot (114%).
 A maximum dust deposition of 8.4 g/m2 over 30-days was calculated at 50 m distance from the road centerline corresponding to 120% of the AAQC (7 g/m2) in absence of dust control with water trucks. At 150 m distance, the maximum dust deposition falls to 2.7 g/m2 (38%). Maximum calculated dustfall at existing residences, institutional buildings, culturally sensitive areas, and future residence plots are 0.52, 0.54, 5.4 and 5.6 g/m2 over 30-days of deposition, respectively. No exceedances are calculated at all sensitive receptors.
 Road traffic is not expected to increase gaseous CACs (NO2, SO2, and CO) concentrations above 5% of the corresponding AAQC or CAAQS at 50 m distance from the road centerline. This percentage is obviously lower at greater distances where sensitive receptors are located at different distances. No exceedances are also noted for PM2.5 outside the road’s ROW.

 Concentration of toxic contaminants (VOCs) at 50 m distance from the road centerline will remain very low (<1% of applicable AAQC). As for B[a]P (as surrogate to PAHs), exceedances are obtained because the background concentration was set equal to the applicable AAQC. In fact, the Project would only add a maximum of 0.13% of the AAQC at 50 m distance.
The results presented above was based on a gravel-surface road design which has the highest potential of dust emissions from vehicular traffic. The quantifiable impact of dust control and pavement surfacing are discussed in Section 7.2.

7 Mitigations Measures and Net Effects
Section 6 presented and discussed the modelling results from emission scenarios that were developed based on expectations (via the preliminary construction plan and traffic projections) while considering typical but still conservative inputs to calculate the emission rates which by extension did not include any specific mitigation measures. This section provides an overview of expected impact of mitigation measures on contaminant concentrations in ambient air surrounding the WSR.

7.1 Construction Phase
An Air Quality and Dust Control Management Plan will be deployed during construction that will include typical mitigation measures such as the use of water sprays from trucks to increase moisture levels in active areas during dry days (e.g., haul/access roads, temporary soil and aggregate stockpiles), the use of environmentally certified equipment (e.g. Tier 4 engines), the use of dust suppression systems at quarries, truck speed limitations, vehicle and heavy equipment movement limitations to designated areas, minimizing idling and so forth. As part of the air quality impact assessment, the following quantifiable control measures were integrated into the emission scenario:
 Water-spraying on-road surface mitigating dust uplifting from heavy-duty trucks.
 The use of at least 80% of mobile and stationary equipment having a Tier 4F engine, when the base scenario only considered Tier 3 engines.
The impact of these measures on the maximum concentrations calculated at 50 and 150 m distance from the road centerline, as well as at the closest point on the periphery of five (5) culturally sensitive areas is provided in Table 7-1. It covers all contaminants and averaging periods for which the Project could potentially add (at 50 m distance) the equivalent of at least 50% of the corresponding AAQC or CAAQS based on results without the mitigation measures. For other contaminants and averaging periods, the mitigation measures would only improve the situation that is already not problematic with regard to air quality. The outcomes are as follows:
 Dust control over road surfaces would have a limited impact on the maximum TSP, PM10 and PM2.5 concentrations, meaning that road emissions are not the predominant source. Dust emissions at the construction site due to bulldozing and road grading are actually the main causes of these high concentrations.
 The maximum dust deposition reduces to 10 g/m2 from 12 g/m2 over 30-days at 50 m distance from the road centerline corresponding to 143% of the AAQC (7 g/m2). The maximum dust deposition stays below the AAQC for all receptors at 150 m distance and beyond including existing residences, institutional buildings, and culturally sensitive areas.
 The use of Tier 4F equipment helps undermine the impact of exhaust emissions on short-term NO2 concentrations, but it does not eliminate the potential of exceedance of the 1-hour CAAQS at culturally sensitive areas up to 150 m from the road centerline instead of up to 600 m without mitigation measures. The 24-hour NO2 AAQC is also exceeded based on calculations at 50 m distance, but the impact of the Project would be cut in half (128% of AAQC instead of 275%).
 In a similar way, the use of Tier 4F equipment would help reduce the maximum concentrations of toxic contaminants (acrolein, benzene, propionaldehyde) in air and would alleviate any exceedance potential for acrolein at culturally sensitive areas and reduce the maximum concentration at 50 m distance for benzene.

Table 7-1: Air Dispersion Modelling Results for the Construction Phase

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Closest location from the road centerline (RCL) for culturally sensitive areas (CHL).

As shown in Table 7-1, exceedances of Ontario AAQC for TSP, PM10, and PM2.5 and CAAQS for NO2 remain a possibility at some culturally sensitive areas, even with the application of mitigation measures specified above. That said, there are elements to consider when analyzing the impact of the construction phase on air quality. For example:
 The potential exceedances only concern short-term AAQC (24-hours and less) and could only occur over a short period (i.e., 1-2 days) at each receptor given that the emission sources will be moving as road construction progresses.
 There will be no long-term health impact based on AAQCs. Ground and vegetation soiling over the government set threshold would also be limited to the road ROW and slightly beyond. No exceedance of the AAQC for dustfall was calculated at culturally sensitive areas even though high particulate matter concentrations were obtained. Soiling would also be of limited time given the short period of dust emissions in an area which deposition would most likely be washed away with precipitations and other natural phenomenon after a while.
 AERMOD integrates local topography into calculations, but it does not consider the presence of vegetation and trees that can act as physical barriers, especially against particulates dispersion further down-wind.
 It is not possible to define the exact combination and space distribution of equipment and activities that will occur at individual sections of the road, and so all potential emissions (dozers, excavators, loaders, etc.) were combined together in a single source as a simplified but conservative approach. For example, all three dozers and graders available on site were considered in operation at the same time and same close area which results in higher localized concentrations but would probably not be the case in reality (or at least there would be some distance between each equipment).
The Air Quality and Dust Control Management Plan will not limit itself to the measures considered in this assessment as there are many other options to mitigate dust uplifting and exhaust emissions. Most of these options like idling minimization, limitation of unnecessary vehicle and heavy equipment movement, and the wetting of soil and aggregate during dry days cannot however be properly translated into the dispersion model and so their potential impact was not calculated here. Moreover, mitigation measures for dozers and graders, which are the main source of particulates near culturally sensitive areas, could include watering but it would not be practical. The management plan could therefore integrate a monitoring procedure with the intent of mitigating the impact of these emissions by controlling (limiting) their usage during unfavorable weather conditions for example.

Finally, it is important to note that no AAQC exceedances were calculated at existing residences and institutional buildings in the Webequie area (where people are mostly present in the area) with and without mitigation measures in place.

7.2 Operation Phase
While it is impossible to have a direct control on emissions from vehicle engines, it is possible to work on dust emissions from the road surface. Considering that part of the road will not be fully surfaced with asphalt or chip seal from the start, the maintenance crew will operate a truck that will spray water over the gravel-surface road from May to November, or when needed. Note that particulate matter in air comes almost exclusively from road dust emissions and less from exhaust gases (representing <1% of total particulates).
The impact of this measure on the maximum concentrations of TSP and PM10 along with dustfall calculated at 50 and 150 m distance from the road centerline, as well as at the closest existing residence, institution, culturally sensitive area and future residence plot is provided in Table 7-2. For other contaminants like gaseous CACs and toxic contaminants, this mitigation measure has no impact but as mentioned in Section 6.2, their maximum concentrations are already low, below any applicable AAQC and CAAQS. The outcome are as follows:
 Road watering during non-winter months slightly helps reduce TSP concentrations in air, enough to be below the AAQC at 50 m distance from the road centerline. PM10 concentrations would however still exceed the applicable AAQC at this distance (140%). The limited impact on maximum concentrations is due to the fact that road watering was not considered during freezing months and that maximum concentrations can occur during this time period.
 The maximum dust deposition reduces to 6.0 g/m2 from 8.4 g/m2 over 30-days at 50 m distance from the road centerline corresponding to 85% of the AAQC (7 g/m2). The maximum dust deposition stays below the AAQC for all receptors at 150 m distance and beyond including existing residences, institutional buildings, culturally sensitive areas and future residential plots.
 Except for PM10 at one culturally sensitive area and one future residential plot which are both fairly close to the road, no AAQC and CAAQS exceedances were calculated at all sensitive receptors when integrating the mitigation measure. When the road will be fully surfaced with asphalt or chipseal, it will result in much lower TSP, PM10 and PM2.5 concentrations in air and dustfall on the ground in the immediate area of the road. The impact of a pavement on particulate emissions was not calculated as part of this study but based on calculated emission factors provided in Table 7-3 from a dirty paved surface compared to the gravel road, the maximum TSP, PM10 and PM2.5 concentrations in air should reduce by at least 50%, which would be enough to eliminate the exceedance of PM10 concentrations at both sensitive receptors noted above.

Table 7-2: Air Dispersion Modelling Results for the Operation Phase

Notes:
Concentrations that are greater than the corresponding AAQC or CAAQS are denoted in bold.
(1) Closest receptors from the road centerline (RCL25) for culturally sensitive areas (CHL), existing residences and institutions (RP01), and future residential plots (FRP42).

Table 7-3: Potential Particulate Emission Reduction with Asphalt or Chip Seal Pavement

8 Concluding Remarks
This report was prepared pursuant to the Climate Change and Air Quality Study Plan with the objective to verify how the Webequie Supply Road Project would impact the ambient air quality around the road and near supportive infrastructure and if there is risk of exceeding a CAAQS or an AAQC applicable in the province of Ontario. Studied air contaminants included the CACs (NO2, CO, SO2, TSP, PM10, PM2.5), ten (10) toxic contaminants from the VOC category (including carbonylic and aromatic compounds), benzo[a]pyrene as a surrogate to PAHs, and DPM. The extent of dustfall was also assessed.
Atmospheric dispersion modelling was carried out using expected but conservative emission scenarios during road construction and the operation phase based on best available information at this time. The emission sources covered in this assessment come essentially from the combustion of diesel fuel or gasoline from land mobile equipment,
heavy-duty trucks and light-duty vehicles during the construction and operation phase of the WSR. The modelling exercise also considered fugitive dust emissions mostly from vehicular traffic on the road and the handling of aggregates and other earth materials during construction.
Ambient concentrations of emitted contaminants were calculated at points of impingement of interest including existing residences or group of residences within the community of Webequie, institutional buildings, culturally sensitive areas, and locations for future residences along the road. This report presented the maximum concentrations expected at these locations for contaminants emitted during each phase with and without mitigation measures in place. The main results of this air quality impact assessment will be documented and summarized in the EAR/IS for the Project and is intended to meet the requirements of both the federal TISG and the provincially approved Terms of Reference.

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