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Air Quality Specialist Report for the Proposed Waste Incinerator at Husab Mine, Namibia

Project done on behalf of SLR Consulting (Namibia) (Pty) Ltd

Report Compiled by: Oladapo Akinshipe

Report No: 16SLR09_Rev.0 | Date: May 2018

Project Manager H Liebenberg-Enslin


Report No.: 16SLR09 Rev. 0.1 ii

Report Details

Reference 16SLR09

Status Rev. 0.1

Report Title Air Quality Specialist Report for the Proposed Waste Incinerator at Husab Mine, Namibia

Date Submitted May 2018

Project Consultant SLR Consulting (Namibia) (Pty) Ltd

Prepared by

Oladapo Akinshipe, PhD. (Env. Tech, Uni. of Pretoria)

Oladapo holds a PhD. degree in Environmental Technology from the University of Pretoria. He is currently employed at

Airshed Planning Professionals as a Senior Air Quality Specialist for five years, focusing primarily in air quality impact

assessments, air quality management plans, air quality monitoring and reporting. Oladapo has worked on various

projects in South Africa, Mozambique, Zambia, Tanzania, Kenya, Namibia and Congo DR. These Projects cuts across

various industries including mining and ore handling, metal recovery, power generation, exploration, chemical,

petrochemical, clay brick, and waste recycling.

Reviewed by Hanlie Liebenberg-Enslin, PhD (University of Johannesburg)

Notice

Airshed Planning Professionals (Pty) Ltd is a consulting company located in Midrand, South Africa, specialising in all

aspects of air quality, ranging from nearby neighbourhood concerns to regional air pollution impacts as well as noise

impact assessments. The company originated in 1990 as Environmental Management Services, which amalgamated

with its sister company, Matrix Environmental Consultants, in 2003.

Declaration

I, Oladapo Akinshipe, as authorised representative of Airshed Planning Professionals (Pty) Ltd hereby confirm my

independence as a specialist and declare that neither I nor Airshed Planning Professionals (Pty) Ltd have any interest,

be it business, financial, personal or other, in any proposed activity, application or appeal in respect of which Airshed

Planning Professionals (Pty) Ltd was appointed as air quality specialists, other than fair remuneration for worked

performed, specifically in connection with the assessment summarised in this report. I also declare that I have expertise

in undertaking the specialist work as required, possessing working knowledge of the acts, regulations and guidelines

relating to the application.

I further declare that I am able to perform the work relating to the application in an objective manner, even if this result in

views and findings that is not favourable to the application; and that I am confident in the results of the studies

undertaken and conclusions drawn as a result of it – as is described in this report.

Copyright Warning

Unless otherwise noted, the copyright in all text and other matter (including the manner of presentation) is the exclusive

property of Airshed Planning Professionals (Pty) Ltd. It is a criminal offence to reproduce and/or use, without written

consent, any matter, technical procedure and/or technique contained in this document.

Revision Record

Revision Number Date Reason for Revision

0 31st January 2018 Draft for review

0.1 2nd May 2018 Incorporation of alternate incinerator unit


Report No.: 16SLR09 Rev. 0.1 iii

Abbreviations

ADMS Atmospheric Dispersion Modelling System

Airshed Airshed Planning Professionals (Pty) Ltd

AQSR Air Quality Sensitive Receptor

ASTM American Society for Testing and Materials

DE Diesel Exhaust

EETM Emissions Estimation Technique Manual

ESL Effects Screening Levels

GLC(s) Ground level concentration(s)

IFC International Finance Corporation

LMO Monin-Obukhov Length

Mtpa Million tons per annum

NAAQS National Ambient Air Quality Standards (South Africa)

NDCR National Dust Control Regulations

NEM:AQA National Environmental Management Air Quality Act (South Africa)

NPI National Pollutant Inventory (Australia)

SA South Africa(n)

SATP Sulphuric Acid Treatment Plant

SU Swakop Uranium

TCEQ Texas Commission for Environmental Quality

TSF Tailings Storage Facility

TSP Total Suspended Particulates

US EPA United States Environmental Protection Agency

VKT Vehicle kilometres travelled

VOC(s) Volatile organic compound(s)

WHO World Health Organization

WRD Waste Rock Dump


Report No.: 16SLR09 Rev. 0.1 iv

Glossary

Air pollution This means any change in the composition of the air caused by smoke, soot, dust (including fly ash),

cinders, solid particles of any kind, gases, fumes, aerosols and odorous substances

Ambient air This is defined as any area not regulated by Occupational Health and Safety regulations

Atmospheric emission or emission

Any emission or entrainment process emanating from a point, non-point or mobile source that results in

air pollution

Averaging period This implies a period of time over which an average value is determined

Dispersion The spreading of atmospheric constituents, such as air pollutants

Dust Solid materials suspended in the atmosphere in the form of small irregular particles, many of which are

microscopic in size

Frequency of Exceedance

A frequency (number/time) related to a limit value representing the tolerated exceedance of that limit

value, i.e. if exceedances of limit value are within the tolerances, then there is still compliance with the

standard

Mechanical mixing Any mixing process that utilizes the kinetic energy of relative fluid motion

Oxides of nitrogen (NOx) The sum of nitrogen oxide (NO) and nitrogen dioxide (NO2) expressed as nitrogen dioxide (NO2)

Particulate Matter (PM)

These comprise a mixture of organic and inorganic substances, ranging in size and shape. These can

be divided into coarse and fine particulate matter. The former is called Total Suspended Particulates

(TSP), whilst PM10 and PM2.5 fall in the finer fraction.

PM10

Particulate Matter with an aerodynamic diameter of less than 10 µm. it is also referred to as thoracic

particulates and is associated with health impacts due to its tendency to be deposited in, and damaging

to, the lower airways and gas-exchanging portions of the lung

PM2.5

Particulate Matter with an aerodynamic diameter of less than 2.5 µm. it is also referred to as respirable

particulates. It is associated with health impacts due to its high tendency to be deposited in, and

damaging to, the lower airways and gas-exchanging portions of the lung

Vehicle Entrainment

This is the lifting and dropping of particles by the rolling wheels leaving the road surface exposed to

strong air current in turbulent shear with the surface. The turbulent wake behind the vehicle continues

to act on the road surface after the vehicle has passed


Report No.: 16SLR09 Rev. 0.1 v

Symbols and Units

°C Degree Celsius

µg Microgram(s)

µg/m³ Micrograms per cubic meter

CO Carbon monoxide

CO2 Carbon dioxide

km Kilometers

m/s Metres per second

m2 Metres squared

mg Milligram(s)

mg/m²-day Milligram per metre square per day

mm Millimeters

NO Nitrogen oxide

NO2 Nitrogen dioxide

NOx Oxides of nitrogen

O3 Ozone

PM Particulate Matter

PM10 Thoracic particulate matter

PM2.5 Respirable particulate matter

SO2 Sulfur dioxide

t/a Tons per annum


Report No.: 16SLR09 Rev. 0.1 vi

Executive Summary

Introduction

Swakop Uranium (Pty) Ltd (SU) holds the mining licence (ML) 171 and Environmental Clearance Certificates (ECCs) for the

Husab Uranium Mine and for its associated linear infrastructure. The mine and processing plant is situated in the northern

most part of the Namib Naukluft National Park, about 12 km south-east of Arandis. Mining started in March 2014 and the

commissioning of the processing plant commenced in December 2016.

Husab Mine currently produces between 3 000 and 7 000 tonnes of uranium oxide per annum though conventional load and

haul open pit mining and ore processing operations. General waste (i.e. non-mineralised waste) from the mining and

processing activities is managed and disposed of according to the approved Husab Mine Environmental Management Plan

(EMP). The waste management strategy at the mine was however recently reviewed and Swakop Uranium proposes some

amendments to the current waste management practices. Swakop Uranium therefore proposes the construction and

operation of an on-site incinerator for the purposes of improved waste management, which will serve as a further

amendment to the approved Husab Mine plan and associated activities.

Airshed Planning Professionals (Pty) Ltd was appointed by SLR Environmental Consulting (Namibia) (Pty) Ltd (SLR) to

undertake an air quality impact assessment (AQIA) study for the proposed incinerator. A study to update the Husab Mine

Dispersion Model was undertaken by Airshed in 2016.

Scope of Work

The scope of work included the following:

• Description of the regional climate and site-specific atmospheric conditions impacting on the dispersion potential of

the site;

• Identification of potentially sensitive receptors within the vicinity of the site;

• Overview of the legislation and regulatory context as it pertains to the regulation of atmospheric emissions and air

pollutant concentrations; and

• Analysis of the baseline air quality based on all available observational data;

• Identification and quantification of emissions emanating from the proposed waste incinerator;

• Simulation of ambient air pollutant concentrations due to waste incinerator operations;

• Evaluation of predicted air pollutant concentrations with ambient air quality limits/ guidelines; and

• Compilation of a short air quality report outlining the methodology, description of baseline, emissions quantification

and modelling results, and cumulative assessment of impacts and recommendations.

Conclusion

A quantitative air quality impact assessment was conducted for the operation of a waste incinerator at Husab Mine. The

proposed incinerator of choice is the INICER8 I8-500 Model, specifically designed to burn at maximum loading of

500 kg/hour as a two-stage incinerator unit comprising of a primary chamber and a secondary “after-burner” chamber. This

after-burner draws in the emissions from the primary chamber, ensuring a clean burn at temperatures ranging from 850 –

1200 oC.

For this study, the South African Minimum Emission Limits for the thermal treatment of general and hazardous waste were

adopted as the emission limits which the incinerator emissions must not exceed. Hence, it is the responsibility of SU to


Report No.: 16SLR09 Rev. 0.1 vii

ensure that the design, installation and operation of the incinerator and associated infrastructure will not result in

exceedance of these limits.

The assessment of the incinerator’s impact on the environment included an estimation of atmospheric emissions using

published US EPA emission factors (both controlled and uncontrolled) for similar incinerator applied to the provided waste-

sources, characteristics and volume, and the simulation of pollutant levels and determination of the significance of impacts.

Pollutants quantified included those most commonly associated with incinerators, including CO, PM10, PM2.5, NO2, Pb, HCl

and SO2. Long-term emissions are simulated on the assumption that the incinerator will run for 24 hours a day, 365 days of

the year. Short term emissions are simulated to reflect the worst-case scenario i.e. the incinerator is run at the maximum

burn rate (500 kg/hour). Hence, calculated emission rates exceed the adopted emission limit (South African emission limits);

suggesting that the emission rates used in this study are worst-case emissions.

The receiving environment was described in terms of local atmospheric dispersion potential, the location of potential air

quality sensitive receptors in relation to the current mining activities. A study to update the Husab Mine Dispersion Model

was completed by Airshed in 2017 (Akinshipe & Liebenberg-Enslin, 2017) and was referenced in assessing impacts due to

proposed incineration emissions together with Husab Mine emissions.

Findings from the assessment indicate that all pollutants assessed (including CO, PM10, PM2.5, NO2, Pb, HCl and SO2) did

not exceed their respective long-term or short-term standards, assessment criteria or guideline values for both mitigated and

unmitigated scenario. The contribution from the waste incinerator’s impacts to the baseline is expected to be minimal with

little or no effect on the cumulative pollutant levels in the region. A significance rating of ‘low’ was assigned to potential

inhalation health impacts associated with all pollutants simulated.

Combined impacts due to proposed waste incineration emissions and Husab Mine emissions for all pollutants were

assigned the same rating as described in Akinshipe & Liebenberg-Enslin (2017).

It is the specialist opinion that the application for the operation of the waste incinerator be granted provided that the

incinerator is operated at optimum combustion conditions and stipulated emission limits are not exceeded. It is therefore

recommended that a stack emission measurement campaign be conducted once the proposed waste incinerator is fully

operational. This is to confirm that the emissions fall within adopted emissions limit.


Report No.: 16SLR09 Rev. 0.1 viii

Table of Contents

Report Details ............................................................................................................................................................................ ii

Abbreviations ............................................................................................................................................................................ iii

Glossary .................................................................................................................................................................................... iv

Symbols and Units ..................................................................................................................................................................... v

Executive Summary .................................................................................................................................................................. vi

Table of Contents..................................................................................................................................................................... viii

List of Tables.............................................................................................................................................................................. x

1 Introduction....................................................................................................................................................................... 1

Scope of Work ........................................................................................................................................................ 1

Description of Project Activities from an Air Quality Perspective ............................................................................ 3

Approach and Methodology .................................................................................................................................... 3

1.3.1 The Identification of Regulatory Requirements and Screening Criteria ............................................................. 3

1.3.2 Study of the Receiving Environment .................................................................................................................. 3

1.3.3 Determining the Impact of the Project on the Receiving Environment .............................................................. 4

1.3.4 Compliance Assessment and Health Risk Screening ........................................................................................ 4

Assumptions, Exclusions and Uncertainties ........................................................................................................... 4

2 Regulatory Requirements and Impact Assessment Criteria............................................................................................. 5

Proposed Guidelines for Husab Mine ..................................................................................................................... 5

Emission Limits ....................................................................................................................................................... 7

3 Description of the Receiving Environment ....................................................................................................................... 9

Air Quality Sensitive Receptors .............................................................................................................................. 9

Atmospheric Dispersion Potential ........................................................................................................................... 9

3.2.1 Topography ...................................................................................................................................................... 11

3.2.2 Surface Wind Field .......................................................................................................................................... 11

3.2.3 Temperature .................................................................................................................................................... 13

3.2.4 Rainfall ............................................................................................................................................................. 14

3.2.5 Atmospheric Stability ....................................................................................................................................... 15

Ambient Air Quality in the Erongo Region ............................................................................................................ 16

3.3.1 Existing Sources of Air Pollution in the Erongo Region ................................................................................... 16

3.3.2 Pollutants of Interest ........................................................................................................................................ 17

Measured Ambient Air Quality at Husab Mine ...................................................................................................... 18

4 Impact on the Receiving Environment............................................................................................................................ 27

Atmospheric Emissions from the Waste Incinerator and Husab Mine activities ................................................... 27


Report No.: 16SLR09 Rev. 0.1 ix

Atmospheric Dispersion Modelling ....................................................................................................................... 29

4.2.1 Dispersion Model Selection ............................................................................................................................. 30

4.2.2 Meteorological Requirements .......................................................................................................................... 30

4.2.3 Source and Emission Data Requirements ....................................................................................................... 30

4.2.4 Modelling Domain ............................................................................................................................................ 31

4.2.5 Presentation of Results .................................................................................................................................... 31

Dispersion Simulation Results, Health Risk and Nuisance Screening (Operational Phase) ................................ 31

4.3.1 Impacts due to the Waste Incinerator Emissions (Incremental) ...................................................................... 31

4.3.2 Contribution of Waste Incinerator Impacts to Total Impacts at Husab Mine .................................................... 35

Impact Significance Rating ................................................................................................................................... 35

5 Conclusions and Air Quality Management Measures .................................................................................................... 38

6 References ..................................................................................................................................................................... 39

7 Annexure 1 – INCINER8 I8-500 Waste Incinerator’s Specification Document .............................................................. 40


Report No.: 16SLR09 Rev. 0.1 x

List of Tables

Table 1: Adopted evaluation criteria for the Husab Mine (Akinshipe & Liebenberg-Enslin, 2017) ............................................. 7

Table 2: South Africa Listed Activity Subcategory 8.1: Thermal treatment of general and hazardous waste ........................... 8

Table 3: Monthly temperature summary (Marble Ridge weather station data, 2014 - 2016) ................................................... 13

Table 4: Typical activities in the region and associated pollutants .......................................................................................... 16

Table 5: NO2, SO2, VOCs and HF hourly concentrations at Husab Mine passive sampling network (red shading represent

potential exceedance of extrapolated hourly concentrations) .................................................................................................. 26

Table 6: Emission estimation techniques and parameters for proposed incinerator ............................................................... 27

Table 7: Waste sources, characteristics and volume (received from SU) ............................................................................... 28

Table 8: Summary of estimated emissions from the proposed Waste Incinerator and Husab Mine activities ......................... 29

Table 9: Maximum GLCs for various pollutants due to waste incineration emissions(incremental) ........................................ 32

Table 11: Percentage contribution of incinerator’s impact compared with total impacts from Husab Mine ............................. 35

Table 12: Impact significance rating table (potential air quality impacts at AQSRs) ................................................................ 37

List of Figures

Figure 1: Husab Mine locality map including the mining licence boundary ................................................................................ 2

Figure 2: AQSRs surrounding the Project area ....................................................................................................................... 10

Figure 3: Period, day- and night-time wind roses (Marble Ridge weather station data, 2014 - 2016) ..................................... 12

Figure 4: Seasonal wind roses (Marble Ridge weather station data, 2014 - 2016) ................................................................. 13

Figure 5: Diurnal temperature profile (Marble Ridge weather station data, 2014 - 2016) ........................................................ 14

Figure 6: Monthly rainfall (Marble Ridge weather station data, 2014 - 2016) .......................................................................... 15

Figure 7: Husab Mine monitoring network ............................................................................................................................... 19

Figure 8: Dustfall deposition rates – Husab Mine monitoring campaign for 2014 .................................................................... 20

Figure 9: Dustfall deposition rates – Husab Mine monitoring campaign for 2015 .................................................................... 21

Figure 10: Dustfall deposition rates – Husab Mine monitoring campaign for 2016 .................................................................. 21

Figure 11: PM10 concentrations (Minivol) at Husab Mine for 2014 (data unavailable from September to December) ............ 22

Figure 12: PM10 concentrations (Minivol sampler) at Husab Mine for 2015 (data unavailable from in January and from

September to December) ......................................................................................................................................................... 23

Figure 13: PM10 concentrations (Minivol sampler) at Husab Mine for 2016 ............................................................................. 24

Figure 14: PM10 and PM2.5 concentrations (Grimm sampler) at Husab Mine for 2014 ............................................................ 24

Figure 15: PM10 and PM2.5 concentrations (Grimm sampler) at Husab Mine for 2015 (data unavailable from January to June)

................................................................................................................................................................................................. 24

Figure 16: PM10 and PM2.5 concentrations (Grimm sampler) at Husab Mine for 2016 (data unavailable from January to April

and in December) .................................................................................................................................................................... 25

Figure 17: Simulated annual average PM10 GLCs due to unmitigated and mitigated incinerator emissions (impacts are low

and below adopted standard) .................................................................................................................................................. 33

Figure 18: Simulated annual average SO2 GLCs due to unmitigated and mitigated incinerator emissions (impacts are low

and below adopted standard) .................................................................................................................................................. 34


Report No.: 16SLR09 Rev. 0.1 1


1 INTRODUCTION

Swakop Uranium (Pty) Ltd (SU) holds the mining licence (ML) 171 and Environmental Clearance Certificates (ECCs) for the

Husab Uranium Mine and for its associated linear infrastructure. The mine and processing plant is situated in the northern

most part of the Namib Naukluft National Park, about 12 km south-west of Arandis (refer to Figure 1). Mining started in

March 2014 and the commissioning of the processing plant commenced in December 2016.

In 2009/2010 Swakop Uranium undertook an Environmental Impact Assessment (EIA) process for the Husab Mine and

related site infrastructure, including a combined waste rock dump (WRD) and tailings storage facility (TSF), i.e. ‘co-disposal

facility’. This EIA was approved by the Ministry of Environment and Tourism (MET) in 2011. Subsequently an EIA

amendment process was conducted and approved (in 2013) for, amongst others, a dedicated TSF and a stand-alone WRD,

opposed to the co-disposal facility.

Husab Mine currently produces between 3 000 and 7 000 tonnes of uranium oxide per annum through conventional load

and haul open pit mining and ore processing operations. General waste (i.e. non-mineralised waste) from the mining and

processing activities is managed and disposed of according to the approved Husab Mine Environmental Management Plan

(EMP). The waste management strategy at the mine was however recently reviewed and Swakop Uranium proposes some

amendments to the current waste management practices. Swakop Uranium therefore proposes the construction and

operation of an on-site incinerator for the purposes of improved waste management, which will serve as a further

amendment to the approved Husab Mine plan and associated activities.

Airshed Planning Professionals (Pty) Ltd was appointed by SLR Environmental Consulting (Namibia) (Pty) Ltd (SLR) to

undertake an air quality impact assessment (AQIA) study for the proposed incinerator. A study to update the Husab Mine

Dispersion Model was undertaken by Airshed in 2016 and is referenced in this study.

Scope of Work

The scope of work included the following:

• Description of the regional climate and site-specific atmospheric conditions impacting on the dispersion potential of

the site;

• Identification of potentially sensitive receptors within the vicinity of the site;

• Review of the legislation and regulatory context as it pertains to the regulation of atmospheric emissions and air

pollutant concentrations, and update where relevant;

• Analysis of the baseline air quality based on all available observational data;

• Identification and quantification of emissions emanating from the proposed waste incinerator;

• Simulation of ambient air pollutant concentrations due to waste incinerator operations;

• Evaluation of simulated air pollutant concentrations with ambient air quality limits/guidelines; and

• Compilation of a short air quality report outlining the methodology, description of baseline, emissions quantification

and modelling results, and cumulative assessment of impacts and recommendations.



Figure 1: Husab Mine locality map including the mining licence boundary



Description of Project Activities from an Air Quality Perspective

Air quality impacts are mainly associated with the operational phase of the incinerator. Installation and commissioning of

the incinerator is not expected to generate significant air quality impacts.

Swakop Uranium proposes to install and operate a waste incinerator at the Husab Mine for the planned incineration of their

waste. The proposed incinerator of choice is the INICER8 I8-500 Model, specifically designed to burn at maximum loading of

500 kg/hour as a two-stage incinerator unit comprising of a primary chamber and a secondary “after-burner” chamber. This

after-burner draws in the emissions from the primary chamber, ensuring a clean burn at temperatures ranging from 850 –

1200 oC.

The incinerator will be fitted with a flue gas cleaning system, which will remove particulates by direct capture in the ceramic

filter; remove acid gases by reaction with hydrated lime and capture of resulting solid; remove condensed heavy metals as

particulates in the filter; and avoid ‘de novo’ dioxin formation by removing necessary reactants before the gases cool to the

temperature where formation occurs (refer to specification manual in Annexure A, Section 7 for more information).

Operation of the incineration will result in particulate matter (PM) as well as gaseous emissions. Gaseous emissions,

associated with incineration, mainly include carbon monoxide (CO), oxides of nitrogen (NOx), sulfur dioxide (SO2), volatile

organic compounds (VOC) as well as metals (these depend on the type of waste).

It is important to note that, in the discussion, regulation and estimation of PM emissions and impacts, a distinction is made

between different particle size fractions, viz. TSP, PM10 and PM2.5. PM10 is defined as particulate matter with an aerodynamic

diameter of less than 10 µm and is also referred to as thoracic particulates. Respirable particulate matter, PM2.5, is defined

as particulate matter with an aerodynamic diameter of less than 2.5 µm. Whereas PM10 and PM2.5 fractions are taken into

account to determine the potential for human health risks, total suspended particulate matter (TSP) is included to assess

nuisance effects.

Approach and Methodology

The approach and methodology followed in the completion of tasks included in the scope of work are discussed below:

1.3.1 The Identification of Regulatory Requirements and Screening Criteria

Since the Namibian Atmospheric Pollution Prevention Ordinance (No. 11 of 1976) does not include any ambient air

standards to comply with, reference was made to the following international guidelines and standards in the evaluation of

ambient air quality impacts and dustfall rates:

• South African National Ambient Air Quality Standards (SA NAAQS) and National Dust Control Regulations (SA

NDCR) as set out in the National Environmental Management Air Quality Act (Act No. 39 of 2004) (NEM:AQA);

• Air Quality Guidelines (AQGs) published by the World Health Organisation (WHO);

• European Community Guidelines (EC) and;

• Screening levels for non-criteria pollutants published by various international institutions.

1.3.2 Study of the Receiving Environment



An understanding of the atmospheric dispersion potential of the area is essential to an air quality impact assessment. Hourly

meteorological data for the period 2014 to 2016 from the Marble Ridge weather station was utilised for the study. The

weather station is located on the Mine site.

1.3.3 Determining the Impact of the Project on the Receiving Environment

The establishment of an emission inventory formed the basis for the assessment of the air quality impacts from the Mine’s

emissions on the receiving environment. In the quantification of emissions, use was made of emission factors which

associate the quantity of release of a pollutant to the related mining and waste incineration activities. Emissions were

calculated using emission factors and equations published by the United States Environmental Protection Agency (US EPA)

and Environment Australia in their National Pollutant Inventory (NPI) Emission Estimation Technique Manuals.

1.3.4 Compliance Assessment and Health Risk Screening

Compliance was assessed by comparing simulated ambient pollutant concentrations (CO, NO2, PM2.5, PM10 and SO2) and

dustfall rates to selected ambient air quality and dustfall criteria. Health risk screening was done through the comparison of

simulated pollutant concentrations (VOC, DPM and SO3) to selected inhalation screening levels.

Assumptions, Exclusions and Uncertainties

The following important assumptions, exclusions and uncertainties to the specialist study should be noted:

• Information required to calculate emissions for the Project operations were provided by SLR and Swakop

Uranium. Where necessary, assumptions were made based on common industry practice and experience.

• Only routine emissions for the incinerator operation were estimated and simulated. Atmospheric releases

occurring due to non-routine conditions were not accounted for. These non-routine releases are expected to be

minimal.

• Emission factors were used to estimate all emissions resulting from the incinerator. These emission factors

generally assume standard operating conditions for the plant.

• Hourly meteorological data for the period 2014 to 2016 from the Marble Ridge weather station was utilised for the

study. The weather station is located at Husab Mine.

• Nitrogen monoxide (NO) is rapidly converted in the atmosphere into the much more poisonous nitrogen dioxide

(NO2). The rate of this conversion process is determined by both the rate of the physical processes of dispersion

and mixing of the plume and the chemical reaction rates. As a conservative measure, all NOx was assumed to be

NO2.

• There will always be some degree of uncertainty in any geophysical model, but it is desirable to structure the

model in such a way to minimize the total error. A model represents the most likely outcome of an ensemble of

experimental results. The total uncertainty can be thought of as the sum of three components: the uncertainty due

to errors in the model physics; the uncertainty due to data errors; and the uncertainty due to stochastic processes

(turbulence) in the atmosphere. Nevertheless, dispersion modelling is generally accepted as a scientific and

valuable tool in air quality management.



2 REGULATORY REQUIREMENTS AND IMPACT ASSESSMENT CRITERIA

This section describes the environmental regulations and guidelines that govern the assessment of the emission limits and

air quality impact resulting from the Husab Mine operations. Air quality guidelines and standards are fundamental to

effective air quality management, providing the link between the source of atmospheric emissions and the user of that air at

the downstream receptor site. Air quality guidelines and standards are based on benchmark concentrations that normally

indicate safe daily exposure levels for most of the population, including the very young and the elderly, throughout an

individual’s lifetime.

The Namibian Atmospheric Pollution Prevention Ordinance (No. 11 of 1976) does not include any ambient air standards to

comply with, only prescribing opacity guidelines for smoke under Schedule 1. It is implied that the Director1 provides air

quality guidelines for consideration during the issuing of Registration Certificates. Registration Certificates are only issued

for “Scheduled Processes” which are processes resulting in noxious or offensive gasses and typically pertain to point source

emissions. The Ordinance defines a range of pollutants as noxious and offensive gasses, but air pollution guidelines are

usually primarily for criteria pollutants namely, sulphur dioxide, oxides of nitrogen, carbon monoxide, ozone, lead and

particulate matter. No ambient air quality guidelines, standards or emission limits exist for Namibia. The recently published

Public and Environmental Health Act 1 of 2015 provide “a framework for a structured uniform public and environmental

health system in Namibia; and to provide for incidental matters”. The act identifies health nuisances, such as chimneys

sending out smoke in quantities that can be offensive, injurious or dangerous to health and liable to be dealt with.

Air pollution guidelines are provided by various countries and organisations for several pollutants namely, SO2, NOx, CO,

ozone, lead and particulate matter. In the absence of guidelines for particulate concentrations for Namibia, reference is

made to the Air Quality Objectives adopted as part of the local Erongo Strategic Environmental Assessment (SEA). These

objectives are based on the World Health Organisation (WHO) interim targets and South African National Ambient Air

Quality Standards of 2009.

Proposed Guidelines for Husab Mine

Proposed evaluation criteria taken from the various international criteria are provided in Table 1. The IFC references the

WHO guidelines but indicates that any other internationally recognized criteria can be used such as the US EPA or the EC.

It was however found that merely adopting the WHO guidelines would result in potential non-compliance in many areas due

to the arid environment in the country, and specifically the Erongo Region. The WHO states that these AQG and interim

targets should be used to guide standard-setting processes and should aim to achieve the lowest concentrations possible in

the context of local constraints, capabilities, and public health priorities. These guidelines are also aimed at urban

environments within developed countries (WHO, 2005). For this reason, the South Africa’s NAAQSs are referenced because

these were developed after a thorough review of all international criteria and selected based on the socio, economic and

ecological conditions of the country. For example, the South African NAAQS for SO2 over a 24-hour average is the same as

the EC limit and the WHO IT-1 of 125 µg/m³. The US EPA and Australian ambient air quality standards are more lenient,

viz. 365 µg/m³ and 209 µg/m³ for 24-hour averages, whereas the WHO IT-2 (50 µg/m³) and Air Quality Guidelines (20

µg/m³) are more stringent. It is best practice (according to the IFC) that a specific industry only contributes 25% of the

applicable air quality standards to allow for additional, future sustainable development in the same airshed.

1 Director means the Director of Health Services of the Administration, and, where applicable, includes any person who, in terms of any authority granted to him under section 2(2) or (3) of the Ordinance.



The proposed evaluation criteria were derived from the WHO interim targets, the South African NAAQSs and Botswana’s

dust deposition evaluation criteria. The criteria were selected on the following basis:

• The WHO interim target 3 (IT3) was selected for particulates since these limits are in line with the South African

NAAQSs, and the latter is regarded feasible limits for the arid environment at Husab Mine.

• Even though PM2.5 emissions are mainly associated with combustion sources and mainly a concern in urban

environments, it is regarded good practice to include it as a health screening criterion given the acute adverse

health effects associated with this fine fraction.

• For SO2, there is no IT3, and the IT2 was selected since the WHO states: “This would be a reasonable and

feasible goal for some developing countries (it could be achieved within a few years) which would lead to

significant health improvements that, in turn, would justify further improvements (such as aiming for the AQG

value)”.

• The WHO provides no interim targets for NOx. The AQGs are in line with the South African NAAQSs and therefore

regarded as achievable limits.

Criteria for the evaluation of dustfall rates are not available from the United States Environmental Protection Agency (US

EPA), European Union (EU), World Health Organisation (WHO), or the World Bank Group (WBG). South Africa, however,

has National Dust Control Regulations2 (NDCR) for maximum monthly dustfall given of 600 mg/m²/day for residential areas;

and 1 200 mg/m²/day for non-residential areas. These standards have been adopted by the Botswana Bureau of Standards

as dust deposition evaluation criteria (BOS 498:2012) for Botswana. Hence, these standards were adopted as criteria for the

Husab Mine due to the similar environmental, social and economic situation to these countries.

Non-criteria pollutants such as VOCs and HF are screened against the Texas Commission on Environmental Quality

(TSEQ) Effects Screening Levels (ESL). The TCEQ-ESL provides short-term and chronic Levels for HF and some of the

VOCs – Benzene, Toluene, Ethyl Benzene and Xylene. It should be noted that ESLs are not ambient air quality standards

and if ambient levels of constituents in air exceed the screening levels it does not necessarily indicate a problem, but should

be viewed as a trigger for a more in-depth review. Further justification for these selected guidelines and international

screening criteria are provided in Akinshipe & Liebenberg-Enslin (2017).

2 Government Gazette, Notice 309 of 2011, 27th of May 2011



Table 1: Adopted evaluation criteria for the Husab Mine (Akinshipe & Liebenberg-Enslin, 2017)

Pollutant Averaging Period Selected Criteria Origin

PM2.5

24-hour Mean (µg/m³) 37.5 (a) WHO IT3 & SA Standard

Annual Mean (µg/m³) 15 WHO IT3

PM10

24-hour Mean (µg/m³) 75 (a) WHO IT3 & SA Standard

Annual Mean (µg/m³) 30 WHO IT3

Dustfall 30-day average

(mg/m2/day)

600 (c) SA NDCR & Botswana residential limit

1200 (c) SA NDCR & Botswana Non-residential limit

SO2

1-hour Mean (µg/m³) 350 (a) EC Limit & SA Standard (no WHO guideline)

24-hour Mean (µg/m³) 50 (b) WHO IT2 (seen as a per 40% of the SA and EC limits)

Annual Mean (µg/m³) 50 SA Standard (no WHO guideline)

NO2

1-hour Mean (µg/m³) 200 (b) WHO AQG & EC & SA Standard

Annual Mean (µg/m³) 40 WHO AQG & EC & SA Standard

VOC (Benzene) Annual Mean (µg/m³) 5 SA Standard (no WHO guideline)

VOC (Toluene) 1-hour Mean (µg/m³) 640 TCEQ Short-term ESL

VOC (Ethyl Benzene) 1-hour Mean (µg/m³) 2560 TCEQ Short-term ESL

VOC (Xylene) 1-hour Mean (µg/m³) 350 TCEQ Short-term ESL

HF

1-hour Mean (µg/m³) 18 TCEQ Short-term ESL

Annual Mean (µg/m³) 8.7 TCEQ long-term ESL

Pb Annual Mean (µg/m³) 5 SA Standard (no WHO guideline)

HCl

1-hour Mean (µg/m³) 190 SA Standard (no WHO guideline)

Annual Mean (µg/m³) 8.4 SA Standard (no WHO guideline)

Notes:

(a) Not to be exceeded more than 4 times per year (SA).

(b) Not to be exceeded more than 3 times per year.

(c) Not to be exceeded more than 3 times per year or 2 consecutive months.

Emission Limits

The Namibian Atmospheric Pollution Prevention Ordinance (No. 11 of 1976) lists waste incineration as Scheduled Process

Number 39. There is however no emission guidelines associated with the Scheduled Processes.

The South African National Environmental Management Air Quality Act (NEMAQA) (Act No. 39 of 2004) published a list of

activities which result in atmospheric emissions and which is believed to have significant detrimental effects on the



environment and human health and social welfare. The Listed Activities and Minimum National Emission Standards were

published on the 22nd November 2013 (Government Gazette, 2013). Thermal treatment of general and hazardous waste is a

Listed Activity in South Africa (Subcategory 8.1) and is subject to all installations treating 10 kg per day of waste or more.

Minimum emission standards (MES) for the thermal treatment of general and hazardous waste applicable to a number of

pollutants are listed in Table 2. The emission limits for New Plant status are applicable to all facilities operational after 1 April

2010.

For this study, the South African MES were adopted as the emission standards which the incinerator emissions must not

exceed. Hence, it is SU responsibility to ensure that the design, installation and operation of the incinerator and associated

infrastructure will not result in exceedance of these limits.

Table 2: South Africa Listed Activity Subcategory 8.1: Thermal treatment of general and hazardous waste

Description: Facilities where general and hazardous waste are treated by the application of heat.

Applications: All installations treating 10 kg (or more) per day of waste.

Substance or mixture of substances Plant status mg/Nm³ under normal conditions of 273 K

and 101.3 kPa.

Common name Chemical symbol

Particulate matter N/A New 10

Carbon monoxide CO New 50

Sulphur dioxide SO2 New 50

Oxides of nitrogen NOx expressed as NO2 New 200

Hydrogen chloride HCl New 10

Hydrogen fluoride HF New 1

Sum of Lead, arsenic, antimony, chromium, cobalt, copper, manganese,

nickel, vanadium)

Pb + As + Sb + Cr + Co + Cu + Mn + Ni + V

New 0.5

Mercury Hg New 0.05

Sum of Cadmium, Thallium Cd + Tl New 0.05

Total organic compounds TOC New 10

Ammonia NH3 New 10

Common name Chemical symbol Plant status ng-iTEQ/Nm³ under normal conditions of

10% O2, 273 K and 101.3 kPa.

Dioxins and furans PCDD/PCDF New 0.1

NOTE: “New” refers to plants that are not yet in operation as at 1st April 2010.



3 DESCRIPTION OF THE RECEIVING ENVIRONMENT

Air Quality Sensitive Receptors

AQSR primarily refer to places where humans reside, as well as schools and hospitals. Ambient air quality guidelines and

standards, as discussed under section 2, have been developed to protect human health. Ambient air quality, in contrast to

occupational exposure, pertains to areas outside of an industrial site boundary where the public has access to and

according to the Air Quality Act, excludes areas regulated under the Occupational Health and Safety Act (Act No 85 of

1993).

The Husab Mine is located 5 km south of the Rössing Uranium mine, which is about 12 km to the southeast of the town of

Arandis and near the Khan River in the Erongo Region of Namibia (Figure 2). The mine site is situated in the northernmost

part of the Namib Naukluft National Park, in an area of relatively high biodiversity. Sensitive receptors in the area include a

major tourism attraction, the Big Welwitschia (Welwitschia miräbilis) located ~8.5 km south of the site. The nearest

residential areas are more than 10 km away.

Atmospheric Dispersion Potential

Physical and meteorological mechanisms govern the dispersion, transformation, and eventual removal of pollutants from the

atmosphere. The analysis of hourly average meteorological data is necessary to facilitate a comprehensive understanding of

the dispersion potential of the site. Parameters useful in describing the dispersion and dilution potential of the site i.e. wind

speed, wind direction, temperature and atmospheric stability, are subsequently discussed. Hourly meteorological data for

the period 2014 to 2016 from the Marble Ridge weather station was utilised for the study. The weather station is located on

the Project site.



Figure 2: AQSRs surrounding the Project area



3.2.1 Topography

The Khan River separates the Husab Mine from Rössing Uranium Mine and the Husab Mountain forms a significant ridge to

the southeast. These topographical features, together with the land-sea interaction from the Atlantic Ocean with the dry

desert environment, influence the local dispersion potential of the site as discussed in the following section.

An analysis of topographical data indicated a slope of less than 1:10 from over most of the study area. Dispersion modelling

guidance recommends the inclusion of topographical data in dispersion simulations only in areas where the slope exceeds

1:10 (US EPA, 2004).

3.2.2 Surface Wind Field

The horizontal dispersion of pollution is largely a function of the wind field. The wind speed determines both the distance of

downwind transport and the rate of dilution of pollutants. The generation of mechanical turbulence is similarly a function of

the wind speed, in combination with the surface roughness.

Period and diurnal wind roses drawn from the Marble Ridge weather station for the period January 2014 to December 2016

are shown in Figure 3. Seasonal variations in the wind field are shown in Figure 4. The wind roses comprise 16 spokes,

which represent the directions from which winds blew during a specific period. The colours used in the wind roses below,

reflect the different categories of wind speeds; the yellow area, for example, representing wind speeds between 4 and 5 m/s.

The dotted circles provide information regarding the frequency of occurrence of wind speed and direction categories. The

frequency with which calms occurred, i.e. periods during which the wind speed was below 1 m/s are also indicated.

From the Marble Ridge weather data (2014 to 2016), the wind field was dominated by winds from the southwest, west and

northeast with less frequent, but strong winds from the northwest and very little from the southeast. An average wind speed

of 3.3 m/s was measured over the period. Day-time wind field was similar to the periodic wind field with less frequent north-

easterly flow, but with stronger winds from this direction. Night-time wind rose reflected an increase in easterly winds and a

decrease in airflow from the west. The night-time airflow was characterised by lower wind speeds. The expected difference

between day and night due to the land-sea interaction is demonstrated in this data set.



Figure 3: Period, day- and night-time wind roses (Marble Ridge weather station data, 2014 - 2016)

During summer, the prevalent winds occur from the west, west-northwest, west-southwest, northwest and southwest. The

prevailing wind field during autumn occurs from the southwest and northeast, with less frequent winds from the west-

southwest and western wind field. During winter season, the prevailing wind field also occurs from the southwest and a much

stronger northeast component. The strongest winds occur from the northeast during this season, representing the so-called

“Berg- or east-wind” conditions. An increase in the west-southwest and western wind field is observed during spring, with the

prevalent wind from the southwest.

Period

Day-time Night-time



Figure 4: Seasonal wind roses (Marble Ridge weather station data, 2014 - 2016)

3.2.3 Temperature

Air temperature provides an indication of the extent of insolation, and therefore of the rate of development and dissipation of

the mixing layer. Monthly mean, maximum and minimum temperatures are given in Table 3 while diurnal and average

monthly temperature trends are presented in Figure 5. Period average, maximum and minimum temperatures were 20°C,

37°C and 8°C respectively. The months with the highest temperature were January and March while the coldest months

were June and July.

Table 3: Monthly temperature summary (Marble Ridge weather station data, 2014 - 2016)

Monthly Minimum, Maximum and Average Temperatures (°C) – January 2014 to December 2016

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Minimum 11.7 10.9 9.9 7.3 7.2 3.5 3.6 4.1 6.2 6.7 8.8 10.0

Average 21.5 21.2 22.2 24.2 23.2 19.0 17.4 17.6 17.5 18.0 19.9 20.8

Maximum 38.7 32.8 38.6 37.7 37.2 33.0 34.0 37.9 37.5 37.8 37.1 35.7

Summer

Winter

Autumn

Spring



Figure 5: Diurnal temperature profile (Marble Ridge weather station data, 2014 - 2016)

3.2.4 Rainfall

Precipitation represents an effective removal mechanism of atmospheric pollutants. Precipitation reduces wind erosion

potential by increasing the moisture content of materials. Rain-days in the Namib Desert are defined as days experiencing

0.1 mm or more rainfall.

The total monthly rainfall for Marble ridge weather station is presented in Figure 5 for the period January 2014 to December

2016. Total monthly rainfall is generally low, ranging from 0 to 36 mm across all three of Husab Mine’s stations. Rainfall data

are missing at the Husab and Ida Camp weather stations during the November and December months. Rainfall in the region

has been reported to occur sporadically and often falling in one area (e.g. thunderstorms) rather than widespread across the

region.



Figure 6: Monthly rainfall (Marble Ridge weather station data, 2014 - 2016)

3.2.5 Atmospheric Stability

The new generation air dispersion models differ from the older models in several aspects, the most important of which are

the description of atmospheric stability as a continuum rather than discrete classes. The atmospheric boundary layer

properties are therefore described by two parameters; the boundary layer depth and the Monin-Obukhov length, rather than

in terms of the single parameter Pasquill Class. The Monin-Obukhov length (LMo) provides a measure of the importance of

buoyancy generated by the heating of the ground and mechanical mixing generated by the frictional effect of the earth’s

surface. Physically, it can be thought of as representing the depth of the boundary layer within which mechanical mixing is

the dominant form of turbulence generation (CERC, 2004). The atmospheric boundary layer constitutes the first few hundred

metres of the atmosphere. During daytime, the atmospheric boundary layer is characterised by thermal turbulence due to the

heating of the earth’s surface. Night-times are characterised by weak vertical mixing and the predominance of a stable layer.

These conditions are normally associated with low wind speeds and lower dilution potential.

The highest concentrations for ground level, or near-ground level releases from non-wind dependent sources would occur

during weak wind speeds and stable (night-time) atmospheric conditions. For elevated releases, such as the Sulphuric Acid

Treatment Plant (SATP) stack and the proposed waste incinerator stack, unstable conditions can result in very high

concentrations of poorly diluted emissions close to the stack. This is called looping and occurs mostly during daytime hours.

Neutral conditions disperse the plume fairly equally in both the vertical and horizontal planes and the plume shape is referred

to as coning. Stable conditions prevent the plume from mixing vertically, although it can still spread horizontally and is called

fanning (Tiwary & Colls, 2010). For ground level releases, such as fugitive dust from mining activities, the highest ground

level concentrations will occur during stable night-time conditions.



Ambient Air Quality in the Erongo Region

3.3.1 Existing Sources of Air Pollution in the Erongo Region

The identification of existing sources of emissions in the region and the characterisation of existing ambient pollutant

concentrations is fundamental to the assessment of the potential for cumulative impacts and synergistic effects given the

current operations and their associated emissions.

The main service and urban areas include: Swakopmund, Walvis Bay, Henties Bay, Wlotzkasbaken, Arandis, Usakos and

Karibib. The towns of Swakopmund, Walvis Bay, Henties Bay, Long Beach, Dolphin Beach, Aphrodite Beach and

Wlotzkasbaken are situated along the west coast and are popular holiday destinations throughout the year. Arandis, Usakos

and Karibib are small towns located inland to the northeast. The Erongo Region is known for its mining operations as well as

commercial and industrial activities associated with fishing and shipping. Along the lower Swakop River, there are several

agricultural small holdings and farms producing fresh products for Swakopmund and other urban areas. Goanikontes is one

such agricultural settlement.

The main sources of air pollution in the region include mining operations, public roads (paved, treated and unpaved), and

natural exposed areas prone to wind erosion. In addition, there are a number of other pollution sources such as harbour

emissions (ships, loading and unloading activities, mobile equipment, etc.), small boilers and incinerators, commercial

activities, etc. Typical activities in the region and associated pollutants are summarized in Table 4.

Table 4: Typical activities in the region and associated pollutants

Air Pollution Sources TSP PM10 PM2.5 SO2 NOx CO VOCs

Mining Operations √ √ √ √ √ √ √

Paved and unpaved roads √ √ √

Vehicle tailpipe emissions √ √ √ √ √ √ √

Wind-blown dust √ √ √

Miscellaneous (small boilers, incinerators, etc.) √ √ √ √ √ √ √

Notes: The size of the mark indicate the prominence of the pollutant

3.3.1.1 Existing Regional Mining Operations

Fugitive dust sources associated with mining activities include drilling and blasting operations, materials handling activities,

crushing and screening, vehicle-entrainment by haul vehicles and wind-blown dust from tailings impoundments and

stockpiles. Mining operations represent potentially the most significant sources of fugitive dust emissions (PM2.5, PM10 and

TSP) with small amounts of NOx, CO, SO2, methane, and carbon dioxide (CO2) being released during blasting operations

and from mine trucks. Known operational mines in the region aside Husab Mine include Rössing Uranium Mine, Langer

Heinrich Uranium Mine and Navachab Gold Mine. Trekkopje Uranium Mine is on care and maintenance, and Norasa

(Valencia) mine is not operational. Exploration sites include the Etango Project (which has a small pilot plant) and the Tumas

Project. There are sand mining operations within the Swakop River, about 20 km east-northeast of Swakopmund close to

Goanikontes, while the Namibia Granite and Stone Products operate near Walvis Bay. These sources are located too far

away to have a significant influence on the air quality at the Husab Project site. Other mining operations in the region include

Africa Range (Old Stone Africa) and related granite stone companies as well as quarrying operations on the Rossing

mountain.



3.3.1.2 Vehicle Exhaust Emissions

There are several main roads within the Erongo Region. The B2 between Swakopmund and Usakos, and Swakopmund and

Henties Bay is most likely the busiest road in the area. Roads within the immediate vicinity of the Husab Mine include the

unpaved C28 through the Namib Naukluft National Park (linking Swakopmund and Windhoek) and the D1991. The

temporary access road towards the Husab Mine turns northwards of the C28 and is now primarily used by the exploration

and monitoring teams, as well as tourists visiting the Welwitschia plant south of the Husab site (no Husab Mine related traffic

uses this road anymore).

Air pollution from vehicle emissions may be grouped into primary and secondary pollutants. Primary pollutants are those

emitted directly into the atmosphere, and secondary, those pollutants formed in the atmosphere due to chemical reactions,

such as hydrolysis, oxidation, or photochemical reactions. The significant primary pollutants emitted by vehicles include CO2,

CO, hydrocarbons (HCs), SO2, NOx, particulates and lead. Secondary pollutants include: nitrogen dioxide (NO2),

photochemical oxidants (e.g. ozone), HCs, sulphuric acid, sulphates, nitric acid and nitrate aerosols. Toxic hydrocarbons

emitted include benzene, 1.2-butadiene, aldehydes and polycyclic aromatic hydrocarbons (PAH). Benzene represents an

aromatic HC present in petrol, with 85% to 90% of benzene emissions emanating from the exhaust and the remainder from

evaporative losses.

3.3.1.3 Fugitive Dust Sources

Fugitive dust emissions may occur due to vehicle entrained dust from local paved and unpaved roads, and wind erosion from

open areas. The extent of particulate emissions from the main roads will depend on the number of vehicles using the roads

and on the silt loading on the roadways. The areas prone to wind erosion within the region of the Husab

Mine are significant. The quantification of these sources is however beyond the scope of this study. The extent, nature and

duration of windblown dust is a function of the moisture, particle size distribution and silt content of soils, the wind speed and

the extent of exposed areas. A distinct thin crust on the surface binds the material reducing the potential for wind erosion

when undisturbed. When disturbed however, very fine loose material is exposed to wind erosion. Aside from gravel roads,

mining activities in the area are the main source of dust generation.

3.3.2 Pollutants of Interest

The main pollutant of concern in the Erongo Region is particulates. The impact of particles on human health is largely

dependent on (i) particle characteristics, particularly particle size and chemical composition, and (ii) the duration, frequency

and magnitude of exposure. The potential of particles to be inhaled and deposited in the lung is a function of the particles

size, shape and density. Air quality guidelines for particulates are given for various particle size fractions, including total

suspended particulates (TSP), and inhalable (PM10) and respirable (PM2.5) particulates. Airborne particles smaller than

10 μm (PM10) are deposited in the nasal region whereas smaller particles (PM2.5) are deposited in the tracheobronchial and

pulmonary regions. More recently the focus of particle monitoring has shifted from PM10 to fine particles (PM2.5), since these

are found to remain in the lowest parts of the lungs and may be a better measure of health impacts. The Strategic

Environmental Management Plan (SEMP) monitoring network include the monitoring of PM10 concentrations at

Swakopmund, Walvis Bay, Henties Bay and at the farm Jakalswater. PM2.5 concentrations are measured at Walvis Bay and

Swakopmund.

The radionuclide content of the inhalable dust fraction is a concern, especially in areas where people reside such as

Swakopmund, Walvis Bay, Henties Bay, Wlotzkasbaken, Long Beach, Dolphin Beach, Aphrodite Beach and Arandis. The

PM10 and PM2.5 concentrations sampled can provide useful information for the radiation assessment, where collected dust

can be analyzed for radionuclide content. Aside from ambient dust concentrations, the associated radionuclides posing a



potential risk to human health and well-being is radon progeny. For this reason, radon is monitored at Swakopmund and near

Arandis.

Measured Ambient Air Quality at Husab Mine

The identification of existing sources of emission and the characterisation of ambient pollutant concentrations is fundamental

to the assessment of the potential for cumulative impacts in the region. Ambient monitoring data (particulates and gases)

was obtained from the Husab Mine monitoring campaign for the period 2014 to 2016 (the same year that was utilised in the

modelling). Ambient monitoring locations from the Husab Mine monitoring campaign are presented illustrated in Figure 7.



Figure 7: Husab Mine monitoring network



3.4.1.1 Dustfall Deposition Rate

Dustfall deposition rates from the Husab Mine monitoring campaign for 2014, 2015 and 2016 are presented in Figure 8,

Figure 9 and Figure 10 respectively. Dustfall rates are generally low for the sampling period and well within the acceptable

dustfall rates of 600 mg/m²/day (adopted limit for residential areas) and 1 200 mg/m²/day (adopted limit for non-residential

areas). The low dustfall rates show slight spatial and temporal variation across the site. During 2014 campaign, deposition

results for EXT03A and EXT 28 exceeded the adopted non-residential limit in August and October respectively; while EXT 03

exceeded the adopted non-residential limit from January to April 2014. This may be attributed to the plant and infrastructure

construction activities. During 2015, Ext 27 exceeded the adopted non-residential limit from May to December; and for all the

months of the year in 2016 (excluding January). These relatively high rates were due to vehicle entrained emissions from the

unpaved roads surrounding the bucket location, fugitive dust due to maintenance activities close to the bucket location, as

well as blasting, ore stockpiling, maintenance and other mining activities from the pit.

Figure 8: Dustfall deposition rates – Husab Mine monitoring campaign for 2014



3.4.1.2 PM10 and PM2.5 Concentrations

PM10 concentrations from the Minivol sampler, at the northern extreme of Pit Zone 1, during the 2014 to 2016 monitoring

campaign are presented in Figure 11, Figure 12 and Figure 13 respectively. PM10 and PM2.5 concentrations from the Grimm

sampler at Husab Mine for the same period (2014, 2015 and 2016) monitoring campaign are presented in Figure 14, Figure

15 and Figure 16. It should be noted that the Minivol samples are taken on a six-daily interval for a 24-hour period, whereas

the Grimm sampler takes measurement continuously.

Minivol Sampler

The adopted PM10 air quality daily guideline (75 µg/m³) for the Husab Mine was exceeded for 5 days in 2014 (equating to

26%), 5 days in 2015 (equating to 22%) and 15 days in 2016 (equating to 38%). The highest concentration sampled during

2014, 2015 and 2016 was 174 µg/m³, 111 µg/m³ and 343 µg/m³ respectively. The annual average PM10 concentration during

2014, 2015 and 2016 was 35 µg/m³, 37 µg/m³ and 72 µg/m³.

Grimm Sampler

The adopted PM10 air quality daily guideline (75 µg/m³) for the Husab Mine was exceeded for 14 days in 2014 (equating to

4.2%), 29 days in 2015 (equating to 16%) and 41 days in 2016 (equating to 18%). The highest concentration sampled during

2014, 2015 and 2016 monitoring campaign was 146 µg/m³, 431 µg/m³ and 325 µg/m³ respectively. The annual average

PM10 concentration during 2014, 2015 and 2016 monitoring campaign was 28 µg/m³, 40 µg/m³ and 41 µg/m³.

The adopted PM2.5 air quality daily guideline (37.5 µg/m³) for the Husab Mine was exceeded for 2 days in 2014 (equating to

1%), 2 days in 2015 (equating to 0.5%) and 3 days in 2016 (equating to 1%). The highest concentration sampled during

2014, 2015 and 2016 monitoring campaign was 58 µg/m³, 45 µg/m³ and 46 µg/m³ respectively. The annual average PM10

concentration during 2014, 2015 and 2016 monitoring campaign was 9 µg/m³, 10 µg/m³ and 9 µg/m³.

Figure 11: PM10 concentrations (Minivol) at Husab Mine for 2014 (data unavailable from September to December)



Figure 12: PM10 concentrations (Minivol sampler) at Husab Mine for 2015 (data unavailable from in January and from

September to December)



Figure 13: PM10 concentrations (Minivol sampler) at Husab Mine for 2016

Figure 14: PM10 and PM2.5 concentrations (Grimm sampler) at Husab Mine for 2014

Figure 15: PM10 and PM2.5 concentrations (Grimm sampler) at Husab Mine for 2015 (data unavailable from January to

June due to machine calibration)



Figure 16: PM10 and PM2.5 concentrations (Grimm sampler) at Husab Mine for 2016 (data unavailable from January to

April due to calibration and in December due to equipment failure)

3.4.1.3 Passive Sampling results

NO2, SO2, VOCs and HF passive sampling was carried out at various intervals during the 2014 to 2016 duration, with each

sampling campaign lasting four weeks at selected monitoring locations. Results of each sampling campaign are presented in

Table 5. To compare to average hourly standards or guidelines, one of Beychok’s method is employed to extrapolate four

weeks averages to hourly concentrations (Beychok, 2005). These extrapolated hourly measurements are generally in

compliance of their respective standards or guidelines, excluding NO2 in 2014 and 2015 (at locations 02, 11, 14, 16 and 20);

SO2 in 2014 (at locations 15 and 19); and HF (at location 08) in 2016. The hourly exceedances measured should not be

regarded as an immediate pollution concern, but an indication to possible long-term exceedance if polution source is not

mitigated.



Table 5: NO2, SO2, VOCs and HF hourly concentrations at Husab Mine passive sampling network (red shading

represent potential exceedance of extrapolated hourly concentrations)

NO2 Concentrations at various locations

Sampling duration 02A 5 8 09A 10 11 12 13 14 15 16 17 19 20

08/05/2014 - 09/07/2014 5.6 3.0 1.6 2.6 2.3 4.4 2.3 – 3.0 4.2 2.2 – 1.9 2.3

08/05/2015 - 08/06/2015 23.1 7.4 4.1 9.3 8.8 15.0 5.9 6.6 12.0 5.5 9.1 3.1 6.2 20.4

09/02/2016 - 09/03/2016 13.9 3.8 2.2 6.53 5.0 12.6 4.5 – 7.9 3.3 7.8 – 3.1 11.3

15/06/2016 - 15/07/2016 1.9 4.7 1.1 3.3 3.9 2.2 1.0 2.3 1.4 0.8 2.9 1.0 1.1 1.6

07/10/2016 - 07/11/2016 3.9 3.3 1.0 4.7 1.1 1.9 0.8 1.6 1.1 1.0 2.9 2.3 1.4 2.2

SO2 Concentrations at various locations


08/05/2014 - 09/07/2014 1.8 7.6 2.3 2.0 2.6 0.5 0.2 – 0.3 44.4 2.3 – 10.2 1.1

08/05/2015 - 08/06/2015 0.6 0.5 4.7 12.5 1.0 0.6 2.7 5.5 0.6 0.7 1.4 2.2 1.3 0.7

09/02/2016 - 09/03/2016 10.7 0.1 1.4 0.3 0.7 0.4 1.8 – 1.4 3.8 9.3 – 1.1 0.2

15/06/2016 - 15/07/2016 0.1 3.4 0.8 0.6 1.4 0.4 0.4 0.1 0.1 0.1 8.1 0.6 0.1 0.3

07/10/2016 - 07/11/2016 1.4 0.6 0.4 3.4 0.8 0.1 0.1 0.3 0.1 0.6 8.1 0.1 0.1 0.4

HF Concentrations at various locations


09/02/2016 - 09/03/2016 0.1 0.1 0.1 0.1 0.1 0.1 0.1 – 0.1 0.1 0.1

0.1 0.1

15/06/2016 - 15/07/2016 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

07/10/2016 - 07/11/2016 0.0 0.0 2.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

VOCs Concentrations at various locations

Sampling duration VOC 02A 5 8 09A 10 11 12 13 14 15 16 17 19 20

07/10/2016 - 07/11/2016

Benzene 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

Toluene 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Ethylbenzene 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

Xylene 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2



4 IMPACT ON THE RECEIVING ENVIRONMENT

Atmospheric Emissions from the Waste Incinerator and Husab Mine activities

A discussion on the emissions quantification techniques for the Husab waste Incinerator is provided in this section. In

quantifying emissions from the incinerator, both controlled and uncontrolled emission factors (EF) as published by the

US EPA (1996) were applied as shown in Table 6 (Controlled EFs were obtained from incinerators that is fitted with an

air pollution control device, while uncontrolled EFs were obtained from incinerators without fitted control device. Waste

sources, characteristics and volume (as received from SU) are presented in Table 7. Long-term emissions are

simulated on the assumption that the incinerator will run for 24 hours a day, 365 days of the year. Short term emissions

are simulated to reflect the worst-case scenario i.e. the incinerator is run at the maximum burn rate (500 kg/hour).

Table 6: Emission estimation techniques and parameters for proposed incinerator

Emission Estimation Technique Input Parameters and Activities

Single valued emission factors for refuse combustion (US EPA, 1996)

Uncontrolled EF

PM10 / PM2.5 – 12.6 kg/Mg

SO2 – 1.73 kg/Mg

NOx – 1.24 kg/Mg

CO – 0.685 kg/Mg

HCl – 3.2 kg/Mg

Pb – 0.107 kg/Mg

Controlled EF (Filter / Sorbent Injection)

PM10 / PM2.5 – 0.09 kg/Mg

SO2 – 0.72 kg/Mg

NOx – 1.24 kg/Mg

CO – 0.685 kg/Mg

HCl – 0.106 kg/Mg

Pb – 0.00013 kg/Mg

EF Calculations:

• EF calculations based on heating value of 10 466 J/g.

• Heating values for different waste composition was obtained/estimated from various literatures (Eboh, et al., 2016; Franjo, et al., 1992; Cooper, et al., 1999).

• Exit temperature (oC): 450

• Stack height (m): 12

• Stack diameter (m): 0.6

• Exit velocity (m/s): 1.8

Long-term emissions are simulated on the assumption that the incinerator will run for 24 hours a day, 365 days of the year. Short term emissions are simulated to reflect the worst-case scenario i.e. the incinerator is run at the maximum burn rate (500 kg/hour).

Note: All PM10 size fractions are also conservatively assumed to be PM2.5.



Table 7: Waste sources, characteristics and volume (received from SU)

Waste source Waste Streams (Types) Comments Estimated Volumes for incineration (received from SU) Estimated Calorific

Value (J/g) a

Estimated Quantity (tons)

All Sites (General Waste)

General waste General Waste / PPE - The common material is cotton/ poly cotton (20%)

Estimated 63 x 15 metric tons of general waste produced a year that can be incinerated

17783 945

Acid Plant & TSF (Radioactive

contaminated)

Dust masks + cartridges

Radioactive contaminated waste 20% including radioactive PPE

400L, 200kg a year 23160 0.20

Overalls 44 x 2 (88); 24 x 2 (44) = 132 pairs 264 kg 23160 0.264

Acid suites 80 pairs 40 kg 23160 0.04

Safety boots 68 pairs 68 kg 36676 0.136

Gum boots 44 pairs 44kg 32037 0.088

FPR (Radioactive contaminated)

Contaminated waste (mostly PPE). 20kg per week = 1040 kg 17783 1.04

CCD/Leach/Ponds (Radioactive

contaminated)

Contaminated PPE (disposable overalls used for pyrolusite make-up)

140kg per week = 7280 kg 17783 7.28

Reagents Area (Hazardous waste)

Hydrochloric acid

Reagents containers waste and sulphur bags

50%

1m3 Flobin @ 2 per month (24 per year) 23000 39.3

Ammonia solution (NH4OH) 1m3 Flobin @ 1 per month (12 per year) 23000 8.19

Sodium Hypochlorite (Germicide) 1m3 Flobin @ 1 Flobin per month (12 per year) 23000 14.8

Allamine 1m3 Flobin (25 per year) 23000 20.5

Modifier (super floc viscosity modifier) 1m3 Flobin (13 per year) 23000 45.5

Empty sulfur bags 52587 empty Sulfur bags, additional ± 35 000 (87587 bags) 16024 87.6

1000L containers 1000lt containers containing grease and oil (1m x 1.2 m) (150

containers per year) 21619 143

Hydrocarbon Waste Waste may contain radioactive

components Hydrocarbon waste 10% Assumed 1% of total waste 23000 131

Comminution (radio-active contaminated)

– 62 Employees

Overall

–

4 issued per year (248 per year = 496kg) 23160 0.496

Safety Boots 2 issued per year (124 per year = 124kg) 36676 0.124

Tyvek Suits 2 issued per employee/month (1488 per year = 744kg) 23160 0.744

NOTE: a Heating values for different waste composition was obtained/estimated from various literatures (Eboh, et al., 2016; Franjo, et al., 1992; Cooper, et al., 1999).



Particulate and gaseous emissions from Husab Mine operational activities (including drilling, blasting, materials

handling, diesel engines emissions, windblown dust from stockpile entrained dust from unpaved roads, crushing and

screening and Plant emissions) have been quantified and simulated in the 2017 study “Air Quality Specialist Report –

Update of the Husab Mine Dispersion Model” (Akinshipe & Liebenberg-Enslin, 2017). Emissions quantified, and air

quality impacts simulated in the above-mentioned report are used to compare to impacts from the waste incinerator. A

summary of emissions quantified based on afore-mentioned emissions factors and assuming the incinerator is operated

continuously throughout a given year is shown in Table 8. Calculated emission rates exceed the adopted emission limit

(Section 2.2), suggesting that the emission rates used in this study are most likely worst-case emissions.

Table 8: Summary of estimated emissions from the proposed Waste Incinerator and Husab Mine activities

Sources/Scenarios Estimated Maximum Gaseous Emissions (tons per annum)

PM10 PM2.5 SO2 NOx CO HCl Pb

Incinerator emissions (uncontrolled) 29.7 29.7 4.1 2.9 1.6 7.5 0.25

Incinerator emissions (controlled) 0.21 0.21 1.69 1.21 0.67 0.25 0.0003

Husab Mine emissions (unmitigated)

(Akinshipe & Liebenberg-Enslin, 2017) 9990 2460 265 1140 483 – –

Husab Mine emissions (mitigated)

(Akinshipe & Liebenberg-Enslin, 2017) 2430 997 265 1140 483 – –

% Unmitigated (Incinerator to Husab) 0.29% 1.20% 1.52% 0.25% 0.33% – –

% Mitigated (Incinerator to Husab) 0.01% 0.02% 0.63% 0.25% 0.33% – –

Sources/Scenarios Estimated Maximum Gaseous Emissions (mg/Nm3) a

PM10 PM2.5 SO2 NOx CO HCl Pb

Incinerator emissions (uncontrolled) 5266 5266 723 518 286 1337 45

Incinerator emissions (controlled) 37.4 37.4 299 214 118 44.3 0.1

NOTE: a Calculations are based on the conservative assumptions that the incinerator will operate continuously

Atmospheric Dispersion Modelling

The assessment of the impact of the mining operations on the environment is discussed in this section. To assess

impact on human health and the environment the following important aspects need to be considered:

• The criteria against which impacts are assessed (Section 2);

• The potential of the atmosphere to disperse and dilute pollutants emitted (Section 3.2); and

• The methodology followed in determining ambient pollutant concentrations and dustfall rates (Section 4.1)

The impact of operations on the atmospheric environment was determined through the simulation of ambient pollutant

concentrations. Dispersion models simulate ambient pollutant concentrations and dustfall rates as a function of source

configurations, emission strengths and meteorological characteristics, thus providing a useful tool to ascertain the

spatial and temporal patterns in the ground level concentrations arising from the emissions of various sources.

Increasing reliance has been placed on concentration estimates from models as the primary basis for environmental

and health impact assessments, risk assessments and emission control requirements. It is therefore important to

carefully select a dispersion model for the purpose.



4.2.1 Dispersion Model Selection

For the current study, it was decided to use the Atmospheric Dispersion Modelling System (ADMS) developed by the

Cambridge Environmental Research Consultants (CERC). CERC was established in 1986, with the aim of making use

of new developments in environmental research from Cambridge University and elsewhere for practical purposes.

CERC's leading position in environment software development and associated consultancy has been achieved by

encapsulating advanced scientific research into several computer models which include ADMS 5. This model simulates

a wide range of buoyant and passive releases to the atmosphere either individually or in combination. It has been the

subject of several inter-model comparisons (CERC, 2000), one conclusion of which is that it tends provide conservative

values under unstable atmospheric conditions in that it predicts higher concentrations than the older models close to

the source.

ADMS 5 is a new generation air dispersion model which differs from the regulatory models traditionally used in a

number of aspects, the most important of which are the description of atmospheric stability as a continuum rather than

discrete classes (the atmospheric boundary layer properties are described by two parameters; the boundary layer depth

and the Monin-Obukhov length, rather than in terms of the single parameter Pasquill Class) and in allowing more

realistic asymmetric plume behaviour under unstable atmospheric conditions. Dispersion under convective

meteorological conditions uses a skewed Gaussian concentration distribution (shown by validation studies to be a

better representation than a symmetric Gaussian expression).

ADMS 5 is currently used in many countries worldwide and users of the model include Environmental Agencies in the

UK and Wales, the Scottish Environmental Protection Agency (SEPA) and regulatory authorities including the UK

Health and Safety Executive (HSE). Concentration and deposition distributions for various averaging periods may be

calculated. It has generally been found that the accuracy of dispersion models improve with increased averaging

periods. The accurate prediction of instantaneous peaks is most difficult and is normally performed with more

complicated dispersion models specifically fine-tuned and validated for the location. For the purposes of this report, the

shortest period modelled is one hour.

4.2.2 Meteorological Requirements

Hourly meteorological data for the period 2014 to 2016 from the Marble Ridge weather station was utilised for the

dispersion simulation. The weather station is located at the Husab Mine site.

4.2.3 Source and Emission Data Requirements

ADMS 5 model is able to model point, jet, area, line and volume sources. Sources were modelled as follows:

• Stacks – modelled as point sources (Waste Incinerator and Husab Mine);

• Unpaved roads – modelled as area sources (Husab Mine);

• Wind erosion – modelled as area sources (Husab Mine);

• Materials handling and crushing and screening – modelled as volume sources (Husab Mine);

• Drilling and blasting – modelled as area sources (Husab Mine); and

• Vehicles exhaust emissions – modelled as line sources (Husab Mine).



4.2.4 Modelling Domain

The dispersion of pollutants expected to arise from proposed activities was modelled for an area covering 40 km (east-

west) by 40 km (north-south). The area was divided into a grid matrix with a resolution of 400 m, with the Husab Mine

infrastructure located centrally. ADMS 5 calculates ground-level (1.5 m above ground level) concentrations and dustfall

rates at each grid and discrete receptor point.

4.2.5 Presentation of Results

Dispersion simulation was undertaken to determine highest hourly, highest daily and annual average ground level

concentrations for each pollutant. These averaging periods were selected to facilitate the comparison of simulated

pollutant concentrations with relevant air quality guidelines and health effect screening levels as well as dustfall

regulations.

Ground level concentration (GLC) isopleths plots presented in this section depict interpolated values from the

concentrations simulated by the model ADMS for each of the receptor grid points specified. Plots reflecting hourly

(daily) and averaging periods contain only the 99.99th percentile of predicted ground level concentrations, for those

averaging periods, over the entire period for which simulations were undertaken. It is therefore possible that even

though a high hourly (daily) average concentration is predicted to occur at certain locations, that this may only be true

for one hour (day) during the year.

Dispersion Simulation Results, Health Risk and Nuisance Screening (Operational Phase)

4.3.1 Impacts due to the Waste Incinerator Emissions (Incremental)

Air pollutants, expected to be released by the proposed incinerator and likely to result in human health impacts, include

CO, PM10, PM2.5, NO2, Pb, HCl and SO2. The maximum simulated annual average concentrations, as well as maximum

short-term concentrations for each pollutant are presented in Table 9. Simulated concentrations for each pollutant were

generally low and well below their respective standards. The contribution of the waste incinerator’s impacts to the

baseline (current ambient air quality) is expected to be minimal with little or no effect on the cumulative pollutant levels

in the region. For this reason, the incremental impacts from waste incinerator are reported.

Annual average GLCs for PM10 and SO2 are presented in Figure 17 and Figure 18. Simulated ground level

concentrations from the other pollutants were too low to show as contours. It should be noted that the concentrations

(contours) shown in the figures are not cumulative but represent the impact from the waste incinerator only. These are

included for information purposes and are below the ambient standard or guidelines for each pollutant.



Table 9: Maximum GLCs for various pollutants due to waste incineration emissions (incremental)

Pollutants

1-Hour (µg/m3) 24-Hour (µg/m3) Annual (µg/m3)

Maximum GLCs

Standard / guideline

Maximum GLCs Standard / guideline

Average GLCs Standard / guideline

Uncontrolled

NO2 99.3 200 – – 1.2 40

SO2 71.2 350 6.0 125 0.9 50

CO 39.3 30 000 – – – –

PM10 – – 20.1 75 9.0 40

PM2.5 – – 20.1 40 9.0 20

HCl 184 190 – – 2.3 8.4

Pb – – – – 0.1 5

Controlled

NO2 41.0 200 – – 0.51 40

SO2 71.2 350 6.6 125 0.89 50

CO 39.3 30 000 – – – –

PM10 – – 0.47 75 0.06 40

PM2.5 – – 0.47 40 0.06 20

HCl 6.1 190 – – 0.08 8.4

Pb – – – – 0.00 5

NOTES: The PM2.5 GLCs was calculated on the conservative assumption that all the PM10 emitted from the incinerator are also PM2.5 fraction



Figure 17: Simulated annual average PM10 GLCs due to unmitigated and mitigated incinerator emissions (impacts are low and below adopted standard)



Figure 18: Simulated annual average SO2 GLCs due to unmitigated and mitigated incinerator emissions (impacts are low and below adopted standard)



4.3.2 Contribution of Waste Incinerator Impacts to Total Impacts at Husab Mine

The percentage contributions of impacts from the proposed waste incinerator was compared with total impacts from all

Husab mining operations (Akinshipe & Liebenberg-Enslin, 2017) and are presented in Table 10. The contribution of the

incinerator ranged from 0.3% to 9.3% for uncontrolled scenario, and from 0.0% to 4.2% for controlled scenario. This

further indicates that the contribution of the waste incinerator’s impacts to the baseline will be minimal with little or no

effect on the cumulative pollutant levels in the region.

Table 10: Percentage contribution of incinerator’s impact compared with total impacts from Husab Mine

Pollutants Maximum Hourly Maximum Daily Annual Average

Uncontrolled

PM10 – 0.52% 2.22%

PM2.5 – 0.52% 2.22%

SO2 9.07% 9.32% 8.54%

NO2 0.94% – 0.60%

CO 1.24% – –

Controlled

PM10 – 0.00% 0.02%

PM2.5 – 0.00% 0.02%

SO2 3.78% 4.19% 3.65%

NO2 0.94% – 0.60%

CO 1.24% – –

Impact Significance Rating

EIA regulations require that impacts be assessed in terms of the nature, significance, consequence, extent, duration

and probability of the impacts; as well as the degree to which these impacts can be reversed; cause irreplaceable loss

of resources, and can be avoided, managed or mitigated. The SLR criteria for assessing impacts are provided in Table

11, while the impact significance rating for potential impacts due to the Husab emissions are presented in Table 12.



Table 11: Criteria for assessing impacts

PART A: DEFINITION AND CRITERIA

Definition of Significance Significance = consequence x probability

Definition of Consequence Consequence is a function of severity, spatial extent and duration

Criteria for ranking

of the

SEVERITY/NATURE

of environmental

impacts

H Substantial deterioration (death, illness or injury). Recommended level will often be violated. Vigorous

community action. Irreplaceable loss of resources.

M Moderate/ measurable deterioration (discomfort). Recommended level will occasionally be violated.

Widespread complaints. Noticeable loss of resources.

L Minor deterioration (nuisance or minor deterioration). Change not measurable/ will remain in the current

range. Recommended level will never be violated. Sporadic complaints. Limited loss of resources.

L+ Minor improvement. Change not measurable/ will remain in the current range. Recommended level will

never be violated. Sporadic complaints.

M+ Moderate improvement. Will be within or better than the recommended level. No observed reaction.

H+ Substantial improvement. Will be within or better than the recommended level. Favourable publicity.


the DURATION of

impacts

L Quickly reversible. Less than the project life. Short term

M Reversible over time. Life of the project. Medium term

H Permanent. Beyond closure. Long term.


the SPATIAL SCALE

of impacts

L Localised - Within the site boundary.

M Fairly widespread – Beyond the site boundary. Local

H Widespread – Far beyond site boundary. Regional/ national

PART B: DETERMINING CONSEQUENCE

SEVERITY = L

DURATION Long term H Medium Medium Medium

Medium term M Low Low Medium

Short term L Low Low Medium

SEVERITY = M

DURATION Long term H Medium High High

Medium term M Medium Medium High

Short term L Low Medium Medium

SEVERITY = H

DURATION Long term H High High High

Medium term M Medium Medium High

Short term L Medium Medium High

L M H

-Localised

-Within site boundary

Site

- Fairly widespread

-Beyond site

boundary - Local

- Widespread - Far

beyond site boundary

- Regional/ national

SPATIAL SCALE

PART C: DETERMINING SIGNIFICANCE

PROBABILITY

(of exposure to

impacts)

Definite/ Continuous H Medium Medium High

Possible/ frequent M Medium Medium High

Unlikely/ seldom L Low Low Medium

L M H

CONSEQUENCE

PART D: INTERPRETATION OF SIGNIFICANCE

Significance Decision guideline

High It would influence the decision regardless of any possible mitigation.

Medium It should have an influence on the decision unless it is mitigated.

Low It will not have an influence on the decision.



Table 12: Impact significance rating table (potential air quality impacts at AQSRs)

Potential Air Quality Impact Severity/ Nature Duration Spatial Scale Consequence Probability Significance

Impacts due to Incineration Emissions

CO, PM10, PM2.5, NO2, Pb, HCl and SO2 impacts LOW LOW LOW LOW MEDIUM LOW

Impacts due to Husab Mine Emissions (refer to Akinshipe & Liebenberg-Enslin (2017))

PM2.5 – Unmitigated HIGH MEDIUM MEDIUM MEDIUM MEDIUM MEDIUM

PM2.5 – Mitigated a LOW MEDIUM LOW LOW MEDIUM LOW

PM10 – Unmitigated HIGH MEDIUM MEDIUM MEDIUM MEDIUM MEDIUM

PM10 – Mitigated LOW MEDIUM LOW LOW MEDIUM LOW

Dustfall – Unmitigated MEDIUM MEDIUM LOW LOW MEDIUM MEDIUM

Dustfall – Mitigated LOW MEDIUM LOW LOW MEDIUM LOW

NO2 MEDIUM LOW MEDIUM LOW MEDIUM LOW

DPM LOW LOW LOW LOW MEDIUM LOW

CO LOW LOW LOW LOW MEDIUM LOW

SO2 LOW LOW LOW LOW MEDIUM LOW

VOC LOW LOW LOW LOW MEDIUM LOW

NOTE: a "Mitigated scenario" relate to mitigation measure required as per the original EIA's for the Husab Mine and the current EMP.



5 CONCLUSIONS AND AIR QUALITY MANAGEMENT MEASURES

A quantitative air quality impact assessment was conducted for the operation of a waste incinerator at Husab Mine. The

proposed incinerator of choice is the INICER8 I8-500 Model, specifically designed to burn at maximum loading

of 500 kg/hour as a two-stage incinerator unit comprising of a primary chamber and a secondary “after-burner” chamber.

This after-burner draws in the emissions from the primary chamber, ensuring a clean burn at temperatures ranging from 850

– 1200 oC.

For this study, the South African Minimum Emission Limits for the thermal treatment of general and hazardous waste (refer

to Section 2) applicable were adopted as the emission standards which the incinerator emissions must not exceed. Hence, it

is SU responsibility to ensure that the design, installation and operation of the incinerator and associated infrastructure will

not result in exceedance of these limits.

The assessment of the incinerator’s impact on the environment included an estimation of atmospheric emissions using

published US EPA emission factors (both controlled and uncontrolled) for similar incinerator applied to the provided waste-

sources, characteristics and volume, and the simulation of pollutant levels and determination of the significance of impacts.

Pollutants quantified included those most commonly associated with incinerators, including CO, PM10, PM2.5, NO2, Pb, HCl

and SO2. Long-term emissions are simulated on the assumption that the incinerator will run for 24 hours a day, 365 days of

the year. Short term emissions are simulated to reflect the worst-case scenario i.e. the incinerator is run at the maximum

burn rate (500 kg/hour). Hence, calculated emission rates exceed the adopted emission limit (South African emission limits);

suggesting that the emission rates used in this study are worst-case emissions.

The receiving environment was described in terms of local atmospheric dispersion potential, the location of potential air

quality sensitive receptors in relation to the current mining activities. A study to update the Husab Mine Dispersion Model

was completed by Airshed in 2017 (Akinshipe & Liebenberg-Enslin, 2017) and was referenced in assessing impacts due to

proposed incineration emissions together with Husab Mine emissions.

Findings from the assessment indicate that all pollutants assessed (including CO, PM10, PM2.5, NO2, Pb, HCl and SO2) did

not exceed their respective long-term or short-term standards, assessment criteria or guideline values for both mitigated and

unmitigated scenario. The contribution from the waste incinerator’s impacts to the baseline is expected to be minimal with

little or no effect on the cumulative pollutant levels in the region. A significance rating of ‘low’ was assigned to potential

inhalation health impacts associated with all pollutants simulated.

Combined impacts due to proposed waste incineration emissions and Husab Mine emissions for all pollutants were

assigned the same rating as described in Akinshipe & Liebenberg-Enslin (2017).

It is the specialist opinion that the application for the operation of the waste incinerator be granted provided that the

incinerator is operated at optimum combustion conditions and stipulated emission limits are not exceeded. It is therefore

recommended that a stack emission measurement campaign be conducted once the proposed waste incinerator is fully

operational. This is to confirm that the emissions fall within adopted emissions limit.



6 REFERENCES

Akinshipe, O. & Liebenberg-Enslin, H., 2017. Air Quality Specialist Report – Update of the Husab Mine Dispersion Model,

Midrand, South Africa: Airshed Planning Profesionals (Pty) Ltd..

Beychok, M. R., 2005. Fundamentals of stack gas dispersion. 4th ed. s.l.:Published by the author.

CERC, 2004. ADMS Urban Training. Version 2. Unit A. s.l.:s.n.

Cooper, C., Kim, B. & MacDonald, J., 1999. Estimating the Lower Heating Values of Hazardous and Solid Wastes. Journal

of the Air & Waste Management Association, 49(4), pp. 471-476.

Eboh, F., Ahlström, P. & Richards, T., 2016. Estimating the specific chemical exergy of municipal solid. Energy Science &

Engineering, 4(3), pp. 217 - 231.

Franjo, C., Ledo, J., Anon, R. & Regueira, L., 1992. Calorific value of municipal solid waste. Environmental Technology,

13(11), pp. 1085-1089.

Tiwary, A. & Colls, J., 2010. Air pollution: measurement, monitoring and mitigation. 3rd Edition ed. Oxon: Routledge.

US EPA, 1996. AP 42, 5th Edition, Volume 1, Chapter 2.1 Solid Waste Disposal - Refuse Combustion, Research Triangle

Park, NC: United States Environmental Protection Agency, .

US EPA, 2004. AERMOD: Description of Model Formulation, s.l.: United States Environmental Protection Agency.



7 ANNEXURE 1 – INCINER8 I8-500 WASTE INCINERATOR’S SPECIFICATION DOCUMENT

Main Branch: Coastal Branch:

13 Walter Street, P.O.Box 6751, Windhoek, Namibia 271 Theo-Ben Gurirab Street Walvis Bay, Namibia

Tel: +264 (61) 224 238, Fax: +264 (61) 233 254 Tel: +264 (64) 206 239, Fax: +264 (64) 206 246 Email: [email protected] Email: [email protected]

DIRECTORS: F .W. BIEDERLACK O. BIEDERLACK E.K. LUND

Reg. No: 95/0003 Page 1 of 7

INCINERATOR INCINER8 is a reputable leading manufacturer of general waste, medical and animal waste incinerators with associated pollution control technology equipment. INCINER8 strives to provide the best technological solution to the ever increasing waste management issues that we face today. As a global company, we continuously strive for excellence in quality and offer great value for money, as well as recognising the importance of culture in business. INCINER8 has an extensive dealer network on every continent and exports to over 172 countries world-wide. Our products are all fully CE certified, ensuring that we meet the highest standards in health & safety, construction and environmental requirements. INCINER8 is committed to the environment and is constantly developing the cleanest and the best incinerators for waste management. Item 1: 1 Off Inciner8 Incinerator

Model: I8-500 TECHNICAL DATA

Fuel Diesel

Chamber Capacity 4.0 m3

Burn rate Up to 500kg per hour

Ash Residue 3-5%

Fuel Consumption 35 – 50 litres per hour

Combustion Chamber Dimensions (L x W x H) 2530 x 1060 x 1500

EXTERNAL DIMENSIONS

Length (mm) 4600

Width (mm) 1300

Height incl. Flue (mm) 5100

Weight (kg) 12000

OPERATION Operating Temperature 850 - 1200 ºC

Residency Time in Secondary Chamber 2 seconds

Temperature Monitoring YES


Reg. No: 95/0003 Page 2 of 7

I8-500 INCINERATOR OVERVIEW Primary combustion chamber:

High quality monolith refractory lining rated up to 1600°C. Monolith design provides the best structural stability, optimal Heat retention (without losses on joints), and makes maintenance extremely simple and cost efficient.

High quality insulation coating. 20mm extra insulation layer. This provides excellent heat retention in the primary chamber, minimizing energy losses (increased efficiency), while protecting outside steel structure providing longer equipment life-time and safer environment for the operators.

Steel structure made of high quality durable steel. Constructed to ensure stability, compact design allows for simple installation and transport of the incinerators.

Steel Structure made of high quality durable steel. Constructed to ensure stability, compact design allows for simple installation and transport of the incinerators.

Treated with special HT paint. Heat resistant to ensure your product stays in great condition.

Internal shape designed for optimal heat distribution Avoiding cold spots and providing liquid retention.

Specially designed ash removal door for easy and efficient ash removal.

Diesel oil or gas burner with improved energy efficiency. Lower emissions of nitrous oxides with working field (100 - 300kW) adjustable for different applications.

Constant ventilation with adjustable air flow to provide optimal combustion conditions and efficient gradual cooling of the system.


Reg. No: 95/0003 Page 3 of 7

Large, full side top loading door.

Fitted with a counterbalance or optional hydraulic opening for easier and faster door operation. Large opening size suitable for waste loading using standard motorized equipment with a bucket or our optional bin tipper system. For more information about automated loading and our optional bin tipper system please contact us.

Secondary chamber (after combustion chamber):

2 second gas retention

High quality monolith refractory lining rated up to 1600ºC Diesel oil or gas burners with improved energy efficiency and low nitrous oxides with a wide working field (20 - 60 kW). Adjustable for different applications. Constant ventilation with adjustable air flow to provide optimal combustion conditions and efficient gradual cooling of the system

Electrical Requirements

400V, three phase 50 - 60Hz, 13-16 amp

110V systems available on request Control panel

Weather resistant, IP65 rated

User friendly & simple to operate

Controls primary and secondary burner

Thermostatic device (for increased fuel efficiency)

HQ durable temperature probe

An example drawing is seen below:


Reg. No: 95/0003 Page 4 of 7

Site Proposal Floor must be solid, and levelled. Concrete floor is preferred for installation. The concrete base is a standard reinforced concrete slab 20cm thick. We recommend replacing the material at a depth of at least 50 cm (applying gravel and compacting to the compressibility modulus M = 80.0 MN/m2) All fuel and electrical installations should be done according to local regulations. Shade / shelter type of weather protection is suggested to protect incinerator from weather. Prefabricated shelters for installation are available.

MODEL I8-500 DETAILS: The I8-500 is a proven and unique design which is currently operating in many different applications throughout the world. They have a high build quality that ensures durability and ease of installation, operation and servicing. Model i8-500 advantages: Ease of Use

Fully automatic control of burners with temperature monitoring display.

90% factory pre-installed for easy and simple on-site installation Fuel Efficiency

35L per hour (dependent on application).

Thick monolith refractory lining rated to 1600°C in main chamber retains heat, increasing efficiency.

Thermostatic control of burners. Quality Built to Last

Heat resistant 5mm steel.

Stainless steel stack.

12cm of refractory lining - steel reinforced


Reg. No: 95/0003 Page 5 of 7

Model i8-500 Key features: Low running and maintenance costs

Automatic and simple to operate control panel

Incineration temperatures in excess of 850°C

5mm steel casing and fully insulate

Dense refractory concrete lining rated to 1600°C

Solid hearth to allow maximum burnout

Large top opening lid for easy loading

Wide door for ash removal

Stainless steel flue as standard

Afterburner fitted as standard

12 month or 400 / 1000 hours warranty.

Easy on-site installation

Optional heat recovery system

Optional stainless steel casing

Optional Gas Cleaning System

Our offer includes: Incinerator I8-1000

Shipping, loading & offloading from overseas to Walvisbay to Swakop Uranium

Incinerator stack self-supporting

Earth of Incinerator & stack

1x 2000L Bulk Diesel Tank filled

Fuel level monitoring on 2000L Tank

Ash trolley

PPE & Tool stand

Dustpan/Ash-scoop

8x Steel Bins for storage of ashes

Fire Extinguisher

1 Year Maintenance & spare parts

Installation, Commissioning & Training

WITH

Pollution Control System (Flue gas filtering System) Item 2: 1 Off Filtering System matched to Incinerator I8-500 Standard Flue gas treatment: Our secondary chamber technology prevents dioxins from cracking into smaller but more reactive molecules, this is known as de novo formation. This can be especially apparent in the presence of heavy metals, which can act as a catalyst. The prevention method can be explained as follows: a self-ignition process forces the micro particulates to pass through a flame curtain, this burns all harmful emissions, gas remnants are then retained in the secondary chamber, through thermal decomposition, and cyclonic air distribution to ensure a clean odorless emission in the form of vapor.


Reg. No: 95/0003 Page 6 of 7

I8-PCS Pollution Control System INCINER8’s pollution control device works in the following manner: once the combustion gases leave the secondary chamber from the incinerator the combustion gases are immediately cooled at the first stage to around 425 degrees to prevent de novo formation of dioxins and furans. The consistent process then passes the combustion gases through a catalytic converter using hydrated lime to act as a reagent to remove acid gases and capture of the resulting solids. The resultant combustion gases are then filtered through ceramic filtration to directly capture and remove particulates. The pollution control device consists of the following elements:

a hood to fit over the existing incinerator flue gas outlet to collect the flue gas with a small amount of ambient air, and ductwork to take the gas to the heat exchanger

an air-cooled heat exchanger with a cooling air fan to cool the flue gas to around 425 degrees

powder dosing unit to add lime to the flue gas to remove acidic components such as HCl

a high temperature ceramic filter cleaning to remove particulate emissions and lime

a fan with connecting ductwork to draw the flue gas through the system

an electrical panel

instruments to display temperature and pressure

an air compressor to provide compressed air for the reverse pulse cleaning system and impact vibrator

all mounted on two skids. On installation the skids will be placed end-to-end and the process, electric and pneumatic connections made.

The specified equipment will:

remove particulates by direct capture in the ceramic filter

remove acid gases by reaction with hydrated lime and capture of the resulting solid

avoid ‘de novo’ dioxin formation by removing necessary reactants before the gases cool to the temperature window where formation occurs

remove condensed heavy metals as particulates in the filter

Filter System Specification Collection Hood and Duct Hood design to fit over existing stack with 50mm clearance Duct design 360 mm diameter duct with flanged connections Material mild steel, painted high temperature black to facilitate heat dispersion Heat Exchanger Design shell and tube design with 100mm nb tubes, flue gas inside Tube material mild steel Case material mild steel Fan centrifugal blower, via slide gate damper Ceramic Filter Number of elements 320 Total filter area 61m2 Filtration medium 10mm thick, vacuum formed ceramic fibres Estimated gas flow up to 6,500 Am3/h at up to 450 C Estimated face velocity up to 3.0 cm/s Vessel material mild steel Reverse pulse cleaning on-line, see attached data sheet Solids removal manually, from debris doors at base of vessel


Reg. No: 95/0003 Page 7 of 7

Powder Feeder Design variable speed screw fed from hopper with lump breaker rotor in base and vibrator discharge aid Powder supply hydrated lime in 25 kg bags Hopper design approximately 65 kg capacity, with lid Vibrator compressed air powered impact vibrator run at timer controlled intervals Lumpbreaker integral claw rotor continuously driven Metering screw single continuously flighted screw driven via manual variator type speed control Fan Fan type Radial bladed centrifugal, stainless steel rotor & shaft Fan capacity Up to 6,000 Am3/h at up to 450 mm w.g. Temperature 550 C maximum, 400 C normal operating Fan speed 2880 rpm nominal, but driven via frequency inverter Installed motor 22 kW, direct drive, IP55 rated Absorbed power 10 kW when up to running temperature Instrumentation and Control Sensors temperature at 3 points, local display dp across filter, local display Frequency inverter drives main fan Electrical Panel Location mounted on frame on skid Specification IP66 with additional weather protection Contents components as required to meet latest IEEE regulations Controls on/off buttons or switches to start/stop equipment items potentiometer to control ID fan speed via frequency inverter Display running/not running lights Compressor Model Atlas Copco lubricated rotary screw compressor mounted on an integral tank

air quality specialist report for the proposed waste ... · air quality specialist report for the...

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