Air Quality and Human Health - CSIRfred.csir.co.za/project/smelter/report/Ch5_Air.pdf · Air Quality and Human Health ... and the World Bank. ... According to the World Bank Pollution

EIA FOR THE PROPOSED COEGA ALUMINIUM SMELTER WITHIN THE COEGA INDUSTRIAL

DEVELOPMENT ZONE, PORT ELIZABETH, SA

FINAL TECHNOLOGY REVIEW REPORT – JULY 2005

CHAPTER 5:

Air Quality and Human Health

5. AIR QUALITY AND HUMAN HEALTH ______________________ 5-1

5.1 Introduction and Methodology __________________________________________ 5-1 5.2 Updated Project Description ___________________________________________ 5-2 5.3 Key Issues potentially affected by the changes in the project proposal __________ 5-5

5.3.1 Construction Phase _________________________________________ 5-5 5.3.2 Operational Phase __________________________________________ 5-5

5.4 Updated impact assessment - Air quality predictions and potential health implications ________________________________________________________ 5-5

5.4.1 Sulphur Dioxide (SO2) ______________________________________ 5-6 5.4.1.1 Annual average _____________________________________________________5-6 5.4.1.2 24-hour maximum ___________________________________________________5-6 5.4.1.3 1-hour maximum ____________________________________________________5-7 5.4.1.4 Summary of health risk from exposure to SO2 emissions from the Coega smelter 5-8 5.4.1.5 Comparison of the SO2 Results_________________________________________5-8

5.4.2 Hydrogen Fluoride (HF) Gas _________________________________ 5-12 5.4.2.1 Annual average ____________________________________________________5-12 5.4.2.2 24-hour maximum __________________________________________________5-12 5.4.2.3 1-hour maximum ___________________________________________________5-13 5.4.2.4 Summary of health risk from exposure to gaseous HF emissions from the smelter 5-13 5.4.2.5 Comparison of the HF Results_________________________________________5-13

5.4.3 Fluoride Deposition ________________________________________ 5-16 5.4.4 Total Suspended Particulates (TSP) _____________________________ 5-18

5.4.4.1 Annual average ____________________________________________________5-18 5.4.4.2 24-hour maximum __________________________________________________5-18 5.4.4.3 Comparison of the TSP Results _______________________________________5-19

5.4.5 Mixture of Chemicals_______________________________________ 5-20 5.4.6 Greenhouse Gases: Carbon Dioxide (CO2) and Perfluorocarbons (PFCs) ____ 5-21 5.4.7 Carbon Monoxide (CO)_____________________________________ 5-22




5.4.8 Polycyclic Aromatic Hydrocarbons (PAHs) ________________________ 5-22 5.4.9 Dust __________________________________________________ 5-23 5.4.10 Odour _________________________________________________ 5-24 5.4.11 Acid Deposition __________________________________________ 5-24 5.4.12 Summary of Impact Assessment of the Proposed Aluminium Smelter________ 5-24

5.5 POLLUTION ABATEMENT AND MITIGATION____________________________ 5-28

5.5.1 During Construction _______________________________________ 5-28 5.5.2 Pollution Control Capacity ___________________________________ 5-28

5.5.2.1 Commissioning ____________________________________________________5-28 5.5.2.2 Normal Operations__________________________________________________5-28

5.5.3 Monitoring______________________________________________ 5-30

5.6 CONCLUSIONS ___________________________________________________ 5-31 5.7 RECOMMENDATIONS ______________________________________________ 5-32

5.7.1 Monitoring______________________________________________ 5-32 5.7.2 Construction _____________________________________________ 5-33 5.7.3 Commissioning and Operations ________________________________ 5-33 5.7.4 Further Studies ___________________________________________ 5-33

5.8 REVIEW OF IMPLICATIONS FOR THE RECORD OF DECISION ____________ 5-34




List of Figures Figure 5.1 Map of the Port Elizabeth/Coega area indicating the relative positions of the

various monitoring and data sites, and the relative location of the 7 receptor areas relative to the Coega IDZ _________________________________________5-4

Figure 5.2 Time series prediction of maximum 1-hour SO2 concentrations for the upside scenario ___________________________________________________________5-9

Figure 5.3 (a) Annual average, (b) 24-hour average and (c) 1-hour average SO2 concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Baseline Scenario___________________________________________________5-10

Figure 5.4 (a) Annual average, (b) 24-hour average and (c) 1-hour average SO2 concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Upside Scenario ____________________________________________________5-11

Figure 5.5 (a) Annual average, (b) 24-hour average and (c) 1-hour average HF concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Baseline Scenario___________________________________________________5-14

Figure 5.6 (a) Annual average, (b) 24-hour average and (c) 1-hour average HF concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Upside Scenario ____________________________________________________5-15

Figure 5.7 Annual particulate fluoride (Fp) deposition (mg/m2) for the proposed Coega Aluminium Smelter – Baseline Scenario _________________________________5-17

Figure 5.8 Annual particulate fluoride (Fp) deposition (mg/m2) for the proposed Coega Aluminium Smelter – Upside Scenario ___________________________________5-17

Figure 5.9 (a) Annual average and (b) 24-hour average total suspended particulate (TSP) concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Baseline Scenario __________________________________________5-19

Figure 5.10 (a) Annual average and (b) 24-hour average total suspended particulate (TSP) concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Upside Scenario____________________________________________5-20

List of Tables Table 5.1 Comparison of total emissions to the atmosphere from the proposed AP50

and AP35 aluminium smelters (Raghubir, 2005) ____________________________5-2 Table 5.2 Comparison of maximum modelled SO2 results for Coega smelter ______________5-8 Table 5.3 Comparison of maximum modelled HF results for Coega smelter______________5-13 Table 5.4 Comparison of maximum modelled Particulate Fluoride results for the

proposed Coega Aluminium Smelter (at the smelter site) ____________________5-16 Table 5.5 Comparison of maximum modelled TSP results for proposed Coega

Aluminium Smelter __________________________________________________5-19 Table 5.6 Comparison of CO2 emissions for the proposed Coega Aluminium Smelter ______5-22 Table 5.7 Comparison of PAH emissions and cancer risk for the proposed Coega

Aluminium Smelter __________________________________________________5-23 Table 5.8 Summary impact assessment of the proposed AP35 smelter project in Coega____5-26




UNITS USED IN THIS CHAPTER Two systems for expressing concentrations of air pollutants are commonly used. Firstly, concentrations may be expressed in parts per million (ppm) or parts per billion (ppb). This usually implies ppm or ppb by volume, which is a mixing ratio. As an example, an SO2 concentration of 20 ppb implies a ratio of 20 molecules of SO2 to a billion molecules of air. Air pollution concentrations are also expressed using Standard International units as mg/m3 or µg/m3. In other words, a concentration expressed as a mass of pollutant per unit volume of air. In this report, concentrations are expressed in µg/m3. In order to convert between ppb and µg/m3 a conversion factor is used which refers to the molecular weight of the pollutant. Thus, each pollutant will have a different conversion factor. The conversion also depends on the temperature. For a temperature of 25ºC the following conversion factors may be applied in this study: Factors for converting from µg/m3 to ppb by volume (from Boer et al., 1998)

Pollutant Conversion factor Sulphur dioxide (SO2) 0.382 Hydrogen fluoride (HF) 1.222




Page 5-1

5. AIR QUALITY AND HUMAN HEALTH

5.1 Introduction and Methodology This chapter is based on the specialist study by Dr Mark Zunckel, Greg Scott, Atham Raghunandan and Marieta Oosthuizen (CSIR), prepared as part of the Technology Review. The chapter addresses issues relating to ambient air quality resulting from emissions from the proposed smelter, and the risk they pose to human health in the various residential areas surrounding the IDZ. The key purpose of the technology review is to identify where the changes in the proposed project may lead to a change in the predicted impacts assessment ratings in the Final EIR (CSIR, 2002b), then re-assess the predicted impacts, as well as the associated management actions to reduce negative impacts. The scope of work for the air quality specialist study included:

Comparison of the atmospheric emissions from the proposed AP50 smelter with a production capacity of 485 000 t/a to two AP35 smelter production scenarios, a baseline scenario (660 000 t/a) and an upside scenario (720 000 t/a).

Remodelling the atmospheric dispersion of pollutants generated by the proposed development. The modelling will utilise the same meteorological data used in the original assessment and will predict the annual average, 24-hour and 1-hour maximum concentrations for sulphur dioxide (SO2), gaseous fluoride or hydrogen fluoride (HF), and particulate matter (PM). The modelling will also estimate the annual average deposition for particulate fluoride (Fp).

Assessment of the modelled predictions in terms of existing and future South African air pollution guidelines and standards, as well as relevant international guidelines and standards, i.e. United States Environmental Protection Agency (US-EPA), World Health Organisation (WHO) and the World Bank.

Evaluation of the risk to human health of atmospheric emissions from the proposed AP35 smelter.

Assessment of greenhouse gas emissions in relation to South Africa’s contribution to the overall load and the country’s international commitments.

Evaluation of the pollution abatement and mitigation measures recommended by the original EIR to ensure these measures are still technically feasible and will adequately mitigate identified impacts.

A summary assessment of the significance of the impacts, including the nature of the impact, the extent, the duration, the intensity and probability. This summary will be compared to the previous impact assessment undertaken for the proposed AP50 smelter and differences will be highlighted.

Review of implications of the revised air quality assessment on the recommendations in the ROD of December 2002.




Page 5-2

5.2 Updated Project Description The main function of the smelter is to produce primary aluminium through the electrolytic reduction of alumina. This reduction process is the major source of air pollutants from an aluminium smelter, mainly SO2 and fluoride (gaseous and particulate). A complete smelter operation, however, includes other major activities that support this main function that also give rise to air pollutants. These activities include the manufacture of anode blocks, the building of cathode potliners and the casting of molten liquid. According to the World Bank Pollution Prevention and Abatement Handbook (World Bank, 1998), atmospheric emissions from aluminium smelters include dust, gaseous and particulate fluorides, sulphur dioxide, carbon dioxide, polycyclic aromatic hydrocarbons (PAHs), tars (coal tar pitch volatiles), carbon tetrafluoride (CF4) and carbon hexafluoride (C2F6). The total emissions to the atmosphere from the 485 000 t/a AP50 technology aluminium smelter are compared to the total emissions from the 660 000 t/a and 720 000 t/a AP35 technology aluminium smelter in Table 5.1. The level of assessment of each of these pollutants in the study is also indicated. The increase in emissions for the AP35 technology smelters relates mostly to the increase in production capacity, i.e. 36% and 48% increase respectively.

Table 5.1 Comparison of total emissions to the atmosphere from the proposed AP50 and AP35 aluminium smelters (Raghubir, 2005)

AMOUNT RELEASED (t/a)

ATMOSPHERIC POLLUTANTS

AP50 technology 485 000 t/a capacity



Level of assessment

Gaseous fluoride (HF) 194 264 288 Quantitative

Particulate fluoride (Fp) 97 132 144 Quantitative

Total fluoride (F) 291 396 432

Dust (TSP) 485 660 720 Qualitative

SO2 13 580 17 097 18 340 Quantitative

CO2 776 000 1 056 000 1 152 000 Qualitative

CO 21 534 29 304 31 968 Qualitative Tar (coal tar pitch volatiles) 19.4 26.4 28.8

PAHs 9.7* 13.2* 14.4* Qualitative

Benzo(a)pyrene 0.0097 0.0133 0.0145 Qualitative

CF4 48.5** 66.0** 72.0** Qualitative

NOx 242.5 330.0 360.0 * This figure is a maximum emission and includes the amount for benzo(a)pyrene. ** This figure is a maximum and is calculated from Aluminium Pechiney/Alcan emission factors




Page 5-3

Due to the changes in the atmospheric emissions it was necessary to remodel all pollutants. The dispersion modelling was undertaken using the California Puff (CALPUFF) suite of models. An upgraded version (Version 5.7) of the CALPUFF model was used for this assessment, as the model has been improved since the air quality modelling undertaken in 2002. The model uses one year of representative meteorological data (i.e. data from the year 2000). The main features of the model remain similar, however, the dispersion algorithms have been improved. Following the air dispersion modelling, an assessment of the risk of the predicted concentrations to human health was made. The modelled results are also compared with the existing South African guideline concentrations as well as the recently published proposed South African standard concentrations. These proposed standards have been published in the South African National Standards (SANS) document entitled “Ambient Air Quality: Limits for Common Pollutants – Edition 1.1” and referred to as SANS 1929:2005. The modelled results are also compared with relevant international guidelines and standards. The study area for this assessment covers approximately 40km x 40km, extending from the central Port Elizabeth area to east of the Sundays Rivers, and inland from the coast for about 30 km. The study area and the relative positions of the various air quality and meteorological monitoring stations are shown in Figure 5.1. Also included on the map are the location of the modelled TAPM (The Air Pollution Model) surface and upper air monitoring stations. Figure 5.1 also indicates the seven receptor areas used in the modelling study. To ensure the maximum potential impact in each of the receptor areas was identified, a range of receptors were modelled in each area and the highest modelled concentration was used in the human health risk assessment. These receptor areas include: Port Elizabeth (CBD area) Bluewater Bay Motherwell Coega Harbour The Sundays River Community (from the river mouth up to Addo town) Addo Elephant National Park Smelter Site.




Page 5-4

Figure 5.1 Map of the Port

Elizabeth/Coega area indicating the

relative positions of the various

monitoring and data sites, and the relative

location of the 7 receptor areas

relative to the Coega IDZ

#

##

#

#

#

E &V

Legend

SaltworksIndustrial area

Formal residential area

Informal residential areaTownship area

Airport IndustriaJagtvlakteWells Estate

Power linesRoadsRailwaysProposed IDZ boundary

Algoa Bay

St Croix Island

Brenton Island

Jahleel Island

Cape Recife

Sea View

Skoenmakerskop

Bluewater Bay

King's Beach

Summerstrand

Colchester

r

Ú

Coega River

Sundays River

Swartkops River

UITENHAGE

PORT ELIZABETH

New Brighton

MotherwellMotherwell

#

KwaZahele

DESPATCH

PE Airporte

N2

Coega

Meteorological monitoring sites Air quality monitoring sites TAPM surface and upper air monitoring sites

Map adapted from the Coega SEA study (CSIR, 1997)




Page 5-5

5.3 Key Issues potentially affected by the changes in the project proposal

5.3.1 Construction Phase

Dust will be generated during construction, especially by those activities relating to the excavation and back fill operations in preparing the construction terraces during the early stages of construction. The addition of a second potline and an additional baking furnace will increase the area of the active construction site. The second potline is being constructed sequentially to the first (i.e. they are not being constructed simultaneously). During windy conditions dust generated by construction activities may impact on areas beyond the fence of the construction site. It must be noted that these impacts will be episodic and will only occur during the construction phase of the project. Mitigation measures to minimise the impact from emissions during construction are provided in Section 5.1. 5.3.2 Operational Phase

The increase in the capacity of the proposed smelter will result in increased atmospheric emissions. The capacity increase from 485 000 t/a to 660 000 / 720 000 t/a results in all atmospheric emissions increasing by approximately 36% / 48% (i.e. identical to the increase in capacity). Mitigation measures to minimise the impact from emissions during the operational phase are provided in Section 5.2.

5.4 Updated impact assessment - Air quality predictions and potential health implications

The assessment of potential impacts on human health is based on the following: nature of the impact, extent, duration, intensity and probability. The nature of the impact, i.e. how health is likely to be affected, has already been described in Section 5 of the original report. The extent, duration and intensity are described in this section using the CALPUFF dispersion modelling results for the same range of pollutants originally modelled. The original modelling assessed three different emission scenarios (i.e. 0.6 kgF/tAl, 0.8 kgF/tAl and 1.0 kgF/tAl). This review only assesses the potential impact of the 0.6 kgF/tAl scenario, since this is the World Bank guideline emission rate and the recommended control technologies comply with World Bank requirements for aluminium smelters. The dispersion patterns for SO2, HF, Fp and TSP are described. The isopleth maps reflect the annual average, 24-hour maximum and 1-hour maximum concentrations. Model outputs for annual periods represent the actual predicted average for that year’s meteorological conditions. Since there is uncertainty in any modelling, a conservative approach has been adopted by the air specialist team. The 24-hour and 1-hour maxima represent an extreme worst-case scenario and is the highest 24-hour and 1-hour concentration at each receptor. For the isopleth maps the maximum value recorded at each grid point at any time in the year is used to calculate the




Page 5-6

isopleths. In reality no such day or hour is likely to occur. The degree of confidence in the predictions is therefore high. The health risk assessment is based on the extreme worst-case scenario as described above. This conservative approach means that if the risk to human health is found to be low, then the chance of an adverse impact on health is minimal and even sensitive individuals will not be affected by the smelter emissions. 5.4.1 Sulphur Dioxide (SO2)

5.4.1.1 Annual average

5.4.1.1.1 Ambient concentration

The annual average dispersion pattern for SO2 is given in Figures 5.2a and 5.3a. Highest concentrations of 16.7 µg/m3 occur on the smelter site under the upside production scenario. The concentration decreases the further one moves from the smelter and the dispersion pattern reflects the dominance of the south-westerly gradient wind which blows the plume towards the northeast. A secondary plume of pollution is also dispersed towards the north. All predicted ambient concentrations, even at the smelter, are well below the current South African guideline of 50 µg/m3. South Africa is currently revising all ambient air quality guideline concentrations as part of the new air quality legislation which will see the introduction of ambient air quality standards. The proposed standards for sulphur dioxide remain at the current guideline concentrations since these are based on the conservative WHO guideline concentrations. 5.4.1.1.2 Health risk

The highest modelled annual average concentration is at the smelter site, with a concentration of 16.7 µg/m3. Although this is not a residential area, workers on site may be exposed to this concentration of SO2. The highest modelled concentration for a residential area is at Motherwell, where the concentration is 6.5 µg/m3. The WHO annual guideline for SO2 is 50 µg/m3. The calculated hazard quotients for the three individuals (an adult, a child of ten years old and an infant of one year) are well below 1 at all receptor points, indicating that potential chronic adverse effects are unlikely to occur, even in sensitive individuals. 5.4.1.2 24-hour maximum


The dispersion pattern for the maximum 24-hour SO2 concentration is shown in Figures 5.2b and 3b. Again, the highest concentration is found over the smelter where concentrations of 64.5 µg/m3 are predicted under the upside production scenario. This is below the revised South African and WHO guideline value of 125 µg/m3. Dispersion is influenced mainly by southerly and south-westerly synoptic scale winds.




Page 5-7

5.4.1.2.2 Health risk

The highest modelled 24-hour maximum concentration (64.5 µg/m3) is again at the smelter site. This concentration is well below the WHO 24-hour guideline of 125 µg/m3 for SO2. The highest concentration for a residential area is at the Sundays River community, where the modelled concentration is 26.4 µg/m3. All hazard quotients calculated are below 1 indicating that it will be highly unlikely for any individual at any of the receptor points to experience adverse health effects as a result of exposure to SO2 from the proposed smelter. 5.4.1.3 1-hour maximum


Maximum 1-hour SO2 concentration isopleths are given in Figures 5.2c and 5.3c. The pattern again indicates transport to the north and north-east by the gradient winds. Highest concentrations of 517.3 µg/m3 are limited to the immediate proximity of the smelter under the upside production scenario. The Californian EPA standard of 660 µg/m3 is not exceeded. There is currently no 1-hour guideline concentration for South Africa, however the proposed 1-hour South African standard of 350 µg/m3 is included in this assessment. This maximum limit is mentioned as a footnote in SANS 1929:2005 and provision is made in the Standard for exceedances of limits to be specified. The predicted average 1-hour concentration is well within the proposed standard of 350 µg/m3, as shown in the one-year time series analysis in Figure 5.2. However, the following exceedances of this proposed standard of 350 µg/m3 are identified from the modelling:

• For the baseline production scenario, the 350 µg/m3 limit is exceeded ten times at the smelter site and once outside the site (near the coast) but still within the IDZ. This totals 11 hours of exceedance in a year of 8784 hours (i.e. 0.12 % of the time).

• For the upside production scenario, the 350 µg/m3 limit is exceeded twelve times at the

smelter site, once outside the site (near the coast) but still within the IDZ, and once immediately outside the IDZ to the east of Motherwell. This totals 14 hours of exceedences in a year of 8784 hours (i.e. 0.16 % of the time).

These exceedances tend to occur during January-February (i.e. in summer) under strong wind conditions (greater than 5 m/s) and at midday/early afternoon, when there is a high degree of turbulence and mixing in the atmosphere. The strong winds force the emissions plume to groundlevel, a phenomenon referred to as “downwash”.




Page 5-8

5.4.1.3.2 Health risk

The maximum-modelled 1-hour sulphur dioxide concentration of 517.3 µg/m3 occurs at the smelter, with the highest concentration (213.2 µg/m3) for a residential area at Motherwell. The maximum off-site concentrations are below the proposed South African 1-hour standard of 350 µg/m3, except for the very infrequent exceedances discussed above. The hazard quotients for an adult, a child and an infant, are below 1 at all receptor points, which means that no impairment of airway function is expected to occur in any individual, whether they are sensitive or healthy. 5.4.1.4 Summary of health risk from exposure to SO2 emissions from the Coega smelter

No acute or chronic health effects are expected in any healthy or sensitive individual exposed to the predicted SO2 concentrations. The significance of the potential impact of SO2 to human health is therefore low. 5.4.1.5 Comparison of the SO2 Results

Table 5.2 shows the comparison of the results between the AP50 and AP35 technologies for SO2 for the Coega Aluminium Smelter.

Table 5.2 Comparison of maximum modelled SO2 results for Coega smelter

Averaging Period

Maximum AP50 Concentrations (µg/m3)

Maximum AP35 Concentrations

(µg/m3) Baseline Scenario


(µg/m3) Upside Scenario

1-hour 345.7 469.6 517.3 24-hour 38.9 58.5 64.5 Annual 13.2 14.7 16.7




Page 5-9

Figure 5.2 Time series prediction of maximum 1-hour SO2 concentrations for the upside scenario

0

100

200

300

400

500

600

1 173 345 517 689 861 1033 1205 1377 1549 1721 1893 2065 2237 2409 2581 2753 2925 3097 3269 3441 3613 3785 3957 4129 4301 4473 4645 4817 4989 5161 5333 5505 5677 5849 6021 6193 6365 6537 6709 6881 7053 7225 7397 7569 7741 7913 8085 8257 8429 8601

Ti me

Proposed SA St andard Coast al Sit e Mot herwell Smelt er Sit e

Proposed SA St andard - 350 ug/ m3




Page 5-10

Max: 14.7 µg/m3 Max: 58.5 µg/m3

(a) (b)

Max: 469.6 µg/m3

(c)

Figure 5.3 (a) Annual average, (b)

24-hour average and (c) 1-hour average SO2 concentration isopleths

(µg/m3) for the proposed Coega Aluminium Smelter – Baseline

Scenario




Page 5-11

Max: 517.3 µg/m3

(c)

(a) (b)

Max: 16.7 µg/m3 Max: 64.5 µg/m3

Figure 5.4 (a) Annual average, (b) 24-hour average and (c) 1-hour

average SO2 concentration isopleths (µg/m3) for the proposed Coega

Aluminium Smelter – Upside Scenario




Page 5-12

5.4.2 Hydrogen Fluoride (HF) Gas

5.4.2.1 Annual average


The annual average dispersion pattern for HF is given in Figures 5.5a and 5.6a.The highest annual average isopleth for HF gas lies just to the northeast of the proposed smelter site where the average concentration is 2.2 µg/m3 (Figure 5.6a). As with SO2, the dispersion pattern for HF reflects the influence of the prevailing south-westerly winds. 5.4.2.1.2 Health risk

The maximum-modelled concentration of 2.2 µg/m3 for HF gas is at the smelter under the upside production scenario, with 0.53 µg/m3 predicted for the Coega harbour. The Sundays River community is expected to be exposed to the highest concentration for a residential area, namely 0.26 µg/m3. All of these concentrations are well below the Californian EPA’s chronic reference exposure level (REL) of 14 µg/m3. The hazard quotients calculated for healthy as well as sensitive individuals, indicate that development of skeletal fluorosis at these concentrations is highly unlikely. 5.4.2.2 24-hour maximum


The dispersion pattern for the maximum 24-hour HF concentration is shown in Figures 5.5b and 5.6b.The 24-hour maximum concentrations show the influence of the land breeze, with the 0.25 µg/m3 isopleth extending out over Algoa Bay. The dispersion pattern is also influenced by the prevailing south-westerly gradient winds. A maximum HF concentration of 3.6 µg/m3 is modelled at the smelter site under the upside production scenario. 5.4.2.2.2 Health risk

As no toxicological or dose response values could be found for a 24-hour exposure period for gaseous fluoride, as such no hazard quotients could be calculated. The highest concentration modelled, 3.6 µg/m3, is at the smelter site. This is below the North Carolina 24-hour guideline of 25 µg/m3 but exceeds the New Zealand guideline of 2.9 µg/m3, although the New Zealand guideline was set based on land-use and not human health.




Page 5-13

5.4.2.3 1-hour maximum


Maximum 1-hour HF concentration isopleths are given in Figures 5.5c and 5.6c. The 1-hour HF concentration reaches a maximum (22.4 µg/m3) over the smelter site (Figure 5.6c). Dispersion is to the northeast, north and south is influenced by both the local topography and the gradient winds. The isopleths extend over Algoa Bay indicating the impact of the river valleys on pollution dispersion. The sea and land breezes also play a role in dispersion as evidenced by the isopleths which extend inland, mainly parallel to the course of the rivers. 5.4.2.3.2 Health risk

The highest 1-hour maximum HF concentration modelled is 22.4 µg/m3 at the smelter site. The highest concentration for a residential area is 5.7 µg/m3 at the Sundays River community. These values are well below the Californian EPA 1-hour REL of 240 µg/m3, as well as the ATSDR’s minimum risk level (MRL) for acute exposure, of 17 µg/m3. The calculated hazard quotients are below 1 for all receptor points at both guideline values. It is therefore highly unlikely that any individual, including sensitive individuals, will experience acute effects, such as irritation of the eyes, nose and throat. 5.4.2.4 Summary of health risk from exposure to gaseous HF emissions from the smelter

No adverse health effects, either acute (such as irritation) or chronic (skeletal fluorosis), are expected in any individual, including sensitive individuals, as a result of gaseous HF emissions from the proposed Coega Aluminium Smelter. The significance of the potential impact of HF to human health is therefore low. 5.4.2.5 Comparison of the HF Results

Table 5.3 shows the comparison of the results between the AP50 and AP35 technology for HF for the proposed Coega Aluminium Smelter.

Table 5.3 Comparison of maximum modelled HF results for Coega smelter

Averaging Period



(µg/m3) Baseline Scenario


(µg/m3) Upside Scenario

1-hour 14.2 21.3 22.4 24-hour 1.4 3.4 3.6 Annual 0.3 2.1 2.2




Page 5-14

Max: 2.1 µg/m3 Max: 3.4 µg/m3

Max: 21.3 µg/m3

(c)

(a) (b)


average HF concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter – Baseline

Scenario




Page 5-15

Max: 22.4 µg/m3

(c)

Max: 2.2 µg/m3

(a)

Max: 3.6 µg/m3

(b)


average HF concentration isopleths (µg/m3) for the proposed Coega

Aluminium Smelter – Upside Scenario

Max: 3.6 µg/m3




Page 5-16

5.4.3 Fluoride Deposition

The annual particulate fluoride deposition is shown in Figures 5.7 and 5.8. Particulate deposition is a function of particle size with particles mostly falling out under the effect of gravity. As may be expected, large particles have a shorter atmospheric life than smaller ones and are deposited closer to the source. Fluoride particles have a mean diameter of 20 µm, with a standard deviation of 10 µm (van Limpt, 1999). The predicted fluoride deposition indicates, as may be expected, maximum deposition at the smelter site. This near-site maximum annual deposition rate is 2.55 g/m2. The deposition rate decreases exponentially with increasing distance from the site and within 2 to 3 km are less than 0.001 g/m2. The South African daily dust deposition classification is classified as slight (<0.25 g/m2/day), moderate (0.25 – 0.5 g/m2/day), heavy (0.5 – 1.2 g/m2/day) and very heavy (>1.2 g/m2/day). These relate to nuisance effects. In all cases, fluoride deposition is below this classification. In other words, fluoride deposition will not result in any nuisance impacts. However, although fluoride deposition rates are low, negative impacts in ecological receptors could occur in the IDZ, or further afield, depending on the tolerance of the specific receptors to fluoride. The receptors may include surface waters and vegetation. A revised assessment of the predicted impacts on the on-site surface waters (in particular, stormwater run-off) as a result of fluoride deposition is included in the specialist study on water quality.

Table 5.4 Comparison of maximum modelled Particulate Fluoride results for the proposed Coega Aluminium Smelter (at the smelter site)

Averaging Period

Maximum AP50 Deposition (g/m2)

Maximum AP35 Deposition (g/m2) Baseline Scenario

Maximum AP35 Deposition (g/m2) Upside Scenario

Annual 1.80 2.34 2.55 Monthly 0.150 0.195 0.213




Page 5-17

Figure 5.7 Annual particulate fluoride (Fp) deposition (mg/m2) for the proposed Coega Aluminium Smelter –

Baseline Scenario

Figure 5.8 Annual particulate fluoride (Fp) deposition (mg/m2) for the proposed Coega Aluminium Smelter –

Upside Scenario

Max: 2 340 mg/m2

Max: 2 550 mg/m2




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5.4.4 Total Suspended Particulates (TSP)

The risk for TSP has been qualitatively addressed by comparing the maximum concentrations modelled with the South African guidelines, as there are no WHO guidelines for particulate matter and no EPA standards for TSP (only for PM10 and PM2.5). If one assumes that the TSP is 100% respirable, then one could compare the predicted concentration with the PM10 or PM2.5 guideline values. It should be borne in mind that TSP is unlikely to be 100% respirable and so this is a conservative approach. Findings in the United States show that PM10 concentrations range from 53% of the ambient standard in the east to 35% of the standard in the west (McCann and Koskey, 1998). The US-EPA uses a default value of 73% respirable (US-EPA, 1991). 5.4.4.1 ANNUAL AVERAGE


The annual average dispersion pattern for TSP is given in Figures 5.9a and 5.10a. The annual average isopleth maps shows dispersion to the northeast and to a lesser extent to the north. The maximum concentration (4.7 µg/m3) occurs at the smelter site under the upside production scenario. 5.4.4.1.2 Health risk

The highest annual average modelled TSP concentration was for the smelter site, where the predicted concentration is 4.7 µg/m3. This is well below the South African TSP guideline of 100 µg/m3. Taking the above assumption into account, this is also well below the South African PM10 guideline of 60 µg/m3 and the US-EPA guideline of 50 µg/m3 (3-year average of the annual arithmetic mean). 5.4.4.2 24-HOUR MAXIMUM


The maximum 24-hour TSP isopleth maps are shown in Figures 5.9b and 5.10b where the influence of both synoptic scale and local winds can be seen to play a role in dispersion. The south-westerly synoptic scale wind disperses pollutants to the northeast, whereas the local sea and land breezes disperse pollutants to the north-northwest and south-southeast respectively. The maximum modelled 24-hour concentration is 7.7 µg/m3 under the upside production scenario. 5.4.4.2.2 Health risk

The highest 24-hour maximum predicted TSP concentration, namely 7.7 µg/m3, is observed on the smelter site. This concentration is also well below the South African guideline of 300 µg/m3.




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Again, if one considers the above assumption of the TSP being 100% respirable, the predicted maximum concentration is also well below the SA PM10 guideline of 180 µg/m3 and the US-EPA PM10 guideline of 150 µg/m3 and the US EPA PM2.5 guideline of 65 µg/m3. 5.4.4.3 COMPARISON OF THE TSP RESULTS

Table 5.5 shows the comparison of the results between the AP50 and AP35 technology for total suspended particulates for the proposed Coega Aluminium Smelter.

Table 5.5 Comparison of maximum modelled TSP results for proposed Coega Aluminium Smelter

Averaging Period



Baseline Scenario


Upside Scenario 24-hour 4.9 7.0 7.7 Annual 1.9 4.2 4.7

Figure 5.9 (a) Annual average and (b) 24-hour average total suspended particulate (TSP) concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter –

Baseline Scenario


(a)

Max: 7.0 µg/m2

(b)




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5.4.5 Mixture of Chemicals

The latest trend worldwide is to consider the chemicals in a risk assessment as a mixture. When chemicals have the same mechanism of action, their potential doses are added (or rather, the hazard quotients (HQ) are added to obtain a hazard index). The goal of the hazard index approach is to construct the plausible toxicity index that would have been calculated had the mixture itself been tested. SO2 and HF do not have the same mechanisms of action but as they both affect the upper respiratory tract, their HQs were therefore added. Applying this approach to the risk assessment of the proposed Coega Aluminium Smelter makes no difference to the prediction of possible adverse effects, as the hazard indices are still below 1 indicating that acute respiratory effects as a result of SO2 and HF gas emissions from the proposed smelter remains highly unlikely.

Figure 5.10 (a) Annual average and (b) 24-hour average total suspended particulate (TSP) concentration isopleths (µg/m3) for the proposed Coega Aluminium Smelter –

Upside Scenario





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5.4.6 Greenhouse Gases: Carbon Dioxide (CO2) and Perfluorocarbons (PFCs)

A greenhouse gas (GHG) is transparent to short wavelength radiation from the sun, but absorbs the long wavelength radiation emitted from the earth, resulting in a warming of the atmosphere, producing what is known as the greenhouse effect. Examples of GHGs are water vapour, carbon dioxide (CO2), methane (CH4), nitrous oxide (NOx), ozone (O3) and chlorofluorocarbons (CFCs). These gases have atmospheric lifetimes from a few years to many decades. The individual effect of the wide range of GHGs is represented by a parameter known as the Global Warming Potential (GWP). The GWP is the ratio of the warming caused by a substance to the warming caused by a similar mass of CO2 calculated over 100 years. Thus, the GWP of CO2 is defined as 1. CFC-12 has a GWP of 8 500, while CFC-11 has a GWP of 5 000 (EPA, 1999). Two greenhouse gases are generated and released during the aluminium reduction process. These are carbon tetrafluoride (CF4) and carbon hexafluoride (C2F6) (World Bank, 1998), which have GPWs of 6 500 and 9 600, respectively (EPA, 1999). This means that over a 100-year period, preventing the emission of one ton of CF4 is equivalent to preventing the emission of 6 500 tons of CO2. Estimated CO2 emissions from the proposed Coega Aluminium Smelter (AP35 technology) will be 1 056 000 t/a under the baseline production scenario and 1 152 000 t/a under the upside production scenario. The total CO2 emission from South Africa is estimated as 294 Mt/a (van der Merwe and Scholes, 1998). This implies that the CO2 emission from the proposed AP35 Project will be either 0.359% or 0.392% of South Africa’s total CO2 emission respectively. The proposed Coega Aluminium Smelter (AP35 technology) will emit up to 72 tons of PFC per annum (CF4 and C2F6), calculated using Aluminium Pechiney emission factors (Raghubir et al., 2002). The ratio of CF4 to C2F6 is typically 10:1. The PFC emission then gives an equivalent CO2 emission of 489 911 t/a. This effectively increases the CO2 emission from the plant by 42% to 1 641 911 t/a or 0.558% of South Africa’s total CO2 emission. South Africa ratified the United Nations Framework Convention on Climate Change in 1997. Since then, other protocols (Kyoto and Marrakech) have been discussed with a view to achieving GHG reductions. It is not clear at this stage which nations will formally commit to reducing GHG emissions and by which period. However, consumers are likely to increasingly put pressure on countries to reduce their GHG emissions. The proposed Coega Aluminium Smelter project’s contribution to the South African greenhouse gas budget is relatively small and the initial assessment is to rate this impact on global warming as low. However, GHG emissions as a result of power usage for the proposed smelter is large by comparison and has not been included in this specialist study for assessment. It is in the generation of this power that the real impact of greenhouse gas emissions is felt. The estimated contribution to GHG emissions from this power generation (coal-based) for the smelter use is ~4% of Eskom’s total CO2 emissions and ~2.2% of South Africa’s CO2 emissions (Eskom’s




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contribution to South Africa’s GHG emissions is ~55%). It is recommended that Alcan investigate the various mechanisms specified by the Kyoto (and Marrakech) protocol, which specify ways by which companies can help to reduce GHG emissions. Table 5.6 shows the comparison of the results between the AP50 and AP35 technology for CO2 for the proposed Coega Aluminium Smelter.

Table 5.6 Comparison of CO2 emissions for the proposed Coega Aluminium Smelter

Greenhouse Gas

Maximum AP50 CO2

Equivalent Emissions (t/year)

Maximum AP35 CO2 Equivalent Emissions

(t/year) Baseline Scenario

Maximum AP35 CO2 Equivalent Emissions

(t/year) Upside Scenario

CO2 776 000 1 056 000 1 152 000 PFC 328 921 449 460 489 911 Total* 1 104 921 1 505 460 1 641 911 *Note – This total does not include greenhouse gas emissions from power generation 5.4.7 Carbon Monoxide (CO)

The carbon monoxide produced in the reduction of aluminium is rapidly oxidized in the reduction cells. As a result the emission of CO to the atmosphere is very small. The impact of CO emissions from the proposed Coega Aluminium Smelter on the ambient environment is therefore expected to be negligible and the significance of this pollutant on human health is low. 5.4.8 Polycyclic Aromatic Hydrocarbons (PAHs)

The emissions of PAHs from the proposed Coega Aluminium Smelter are expected to be relatively small (13.2 t/a baseline scenario and 14.4 t/a upside scenario). Most PAHs from anode effects are combusted in the high operating temperatures in the reduction cells, while scrubbing before being released to the atmosphere reduces PAHs generated in the paste plant. There are no environmental guidelines for PAHs as a mixture. However, the ACGIH recommend that occupational exposure by all routes should be carefully controlled to levels as low as possible (ACGIH, 2001). There are two main concerns as far as health effects of PAHs are concerned, namely that PAHs can accumulate in the body and that some PAHs can cause cancer. Evidence exists to indicate that certain PAHs are carcinogenic in humans and animals. The evidence in humans comes primarily from occupational studies of workers who were exposed to mixtures containing PAHs as a result of their involvement in such processes as coke production, roofing, oil refining, or coal gasification (e.g. coal tar, coke oven emissions, soot, shale, and crude oil). Cancer associated with exposure to PAH-containing mixtures in humans occurs predominantly in the lungs and skin following inhalation and dermal exposure, respectively




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(ATSDR,1997). To determine the risk of PAHs in this study it was decided to determine the incremental cancer risk of benzo(a)pyrene (BaP), the only PAH for which there is a quantitative cancer risk estimate. The inhalation unit risk set by the WHO for lung cancer in humans, namely 0.087µg/m3 was used (WHO, 1999). Modelling to estimate ambient concentrations of BaP assumed that the total maximum emission (0.0143 t/a) is released to the atmosphere via the stack on the paste plant, i.e. the FTC stack. The incremental cancer risk was determined for an individual exposed to the maximum annual concentration of BaP. It was assumed that this individual would be exposed to this concentration for 24 hours a day, 350 days per year for 10 years as a child and 30 years as an adult (thus 40 years in total) over a lifetime of 65 years. The highest risk for such an individual, that of 4.60 in ten million, occurs at the smelter site. This risk remains well below the generally acceptable cancer risk of one in a million. For the other receptor areas, the risk varies between 1.28 in ten million at the harbour and no risk at all in Port Elizabeth. Table 5.7 shows the comparison of the results between the AP50 and AP35 technology for PAHs for the proposed Coega Aluminium Smelter. Table 5.7 Comparison of PAH emissions and cancer risk for the proposed Coega

Aluminium Smelter

AP50 Smelter AP35 Smelter Baseline Scenario

AP35 Smelter Upside Scenario

Emission 0.0097 t/year 0.0132 t/year 0.0143 t/year Max. Cancer Risk 3.10 : 10 000 000 4.22 : 10 000 000 4.60 : 10 000 000 5.4.9 Dust

Aluminium smelters are not major sources of dust during normal operations. Dust is however generated in various stages of the process. This dust is emitted via the respective stack or through the roof vents. In this study this dust is regarded as TSP and is assessed in detail in Section 4.4. Not all dust emissions from the plant are quantifiable, e.g. dust from spillages, sweeping, etc. These emissions have been included in the assessment by including a dust emission from the site area of 0.01 kg/tAl. Dust will however be generated during the construction phase, particularly the early excavation period. This dust may have a nuisance impact beyond the immediate region under windy conditions. Management measures to minimise or mitigate the impact are discussed in Section 5. The significance of this dust on the surroundings is considered to be medium without this mitigation, and low if the recommended mitigation measures are applied.




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5.4.10 Odour

SO2 has a minimum odour detection threshold in concentrations of 800 to 2500 µg/m3 (1000 to 3000 ppb). The results of the dispersion modelling indicate that emissions from the proposed Coega Aluminium Smelter are highly unlikely to result in ambient concentrations of SO2 that exceed this minimum value. It is therefore highly unlikely that any impact from odours will occur from normal operations at the proposed Coega Aluminium Smelter. The significance of this impact is therefore low. 5.4.11 Acid Deposition

Acid deposition, both wet (acid rain or mist) and dry, results from the chemical transformation of SO2 (and other pollutants) in the atmosphere with water vapour to form a weak solution of acidic droplets, or acidic aerosols. Acid deposition is a regional scale phenomenon brought about by the scale of rain formation mechanisms, atmospheric transport mechanisms and the chemical transformation rate. For example, industrial emissions of sulphur are transported and deposited in dry and wet forms over much of southern African (Zunckel et al., 2000). The impact of emissions on atmospheric deposition on a local scale is thus difficult to quantify. Rainwater acidity in South Africa is controlled by a number of emission source types. These include industrial emissions, emissions from biomass burning, domestic emissions and terrestrial emissions from agricultural activities, wind blown dust and unpaved roads (Galpin and Turner, 1999). The main industrial contribution is from SO2 derived in the combustion of coal for power generation. The SO2 emission from the proposed Coega Aluminium Smelter is small when compared to the total SO2 emissions from power generation sector. SO2 emissions from the smelter will contribute in a small way to the formation of acidic droplets and aerosols over the region. These, in turn, may precipitate out over the area where they form, but they may also be transported out of the immediate area and precipitate elsewhere in time. This is particularly the case when considering the prevailing westerly synoptic scale transport associated with the main rain-bearing systems. Similarly, acidic droplets or aerosols that form elsewhere may be transported to and precipitate out over the Coega region. By example, Zunckel et al., (1999) attribute seasonal dry sulphur deposition rates of between 3 and 5 mg/m2, at Ben MacDhui in the mountains of the Eastern Cape, to industrial emissions of SO2 on the Mpumalanga Highveld. The significance of this impact is considered low. 5.4.12 Summary of Impact Assessment of the Proposed Aluminium Smelter

Table 5.8 provides a summary of the potential impact of the proposed smelter on human health. The significance of the impact takes into account the nature of the impact, extent, duration, intensity, probability of occurrence and confidence in the predicted modelling results. It must be noted that the summary of the impact assessment between the AP50 and AP35 technology




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smelters remains the same. Ambient concentrations and deposition rates have increased between the two development scenarios, however the modelled concentrations and deposition rates remain below South African and international guidelines and standards, except in the case of the maximum-modelled 1-hour concentration of SO2.




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Table 5.8 Summary impact assessment of the proposed AP35 smelter project in Coega

Impact of pollutant Pollutant Extent Duration Intensity Probability of

occurrence Status Confidence Significance

(without mitigation)

Significance (with

mitigation) SO2 Immediate area Long term Low Improbable Negative High Low Low

HF Immediate area Long term Low Improbable Neutral High Low Low

Fp Immediate area Long term Low Improbable Negative High Low Low

TSP Immediate area Long term Low Improbable Negative High Low Low

CO2 & PFC (from smelter) Global Long term to

permanent Medium Probable

Negative Medium Low Low

CO2 & PFC (from power generation Global Long term to

permanent Medium Highly probable Negative Low Medium Medium/Low

CO Immediate area Long term Low Improbable Neutral Medium Low Low

PAH Immediate area Long term Low Improbable Neutral Medium Low Low

Dust (construction) Immediate area Short term Low Highly probable Negative High Medium Low

Dust (smelter operations) Immediate area Long term Low Improbable Neutral High Low Low

Odour Immediate area Long term Low Improbable Neutral High Low Low

Acid deposition Regional, possibly national Long term Medium Improbable Negative High Low Low




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Extent - this indicates whether the impact will be local and limited to the immediate area of development (the site or the servitude corridor); limited to within 5km of the development;

or whether the impact may be realised regionally, nationally or even internationally.

Duration - this reviews the lifetime of the impact, as being short term (0 - 5 years), medium (5 - 15 years), long term (>15 years but where the impacts will cease after the operation of the site), or permanent.

Intensity – this establishes whether the impact is destructive or innocuous and is described as either low (where no environmental functions and processes are affected), medium (where the environment continues to function but in a modified manner) or high (where environmental functions and processes are altered such that they temporarily or permanently cease).

Probability - this considers the likelihood of the impact occurring and is described as improbable (low likelihood), probable (distinct possibility), highly probable (most likely) or definite (impact will occur regardless of prevention measures).

Status of the impact - a description as to whether the impact will be positive (a benefit), negative (a cost), or neutral.

Degree of confidence in predictions - the degree of confidence in the predictions, based on the availability of information and specialist knowledge.




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5.5 POLLUTION ABATEMENT AND MITIGATION 5.5.1 During Construction

Sand and dust is readily carried aloft during windy conditions in the Coega area. Examples of PM10 concentrations exceeding air quality guidelines are not uncommon. This condition has been observed to be worse when the surface is disturbed by construction activities (Ecoserv, 2001). This fact makes it imperative that dust generated through the construction activities of the Coega Aluminium Smelter is minimised through focused management and adherence to dust minimisation practices. The original air quality assessment for the AP50 technology smelter indicated that the dust management plan should include the following:

• Removal of vegetation limited to only what is necessary to accommodate construction activities.

• Spraying of unpaved site roads and access roads with water routinely throughout construction to contain dust. Water (possibly sea water) can be used as a wetting or binding agent on the unpaved roads and terraces.

• Traffic control measures to limit vehicle-entrained dust from unpaved roads e.g. by limiting vehicle speeds and by restricting traffic volumes.

• Use of a motorized sweeper or vacuum vehicle on surfaced roads, to reduce the presence of sand.

• Re-vegetation of the construction terraces once all of the construction is completed, and when the laydown area is vacated.

The construction area for the proposed Coega Aluminium Smelter project will be smaller than the area originally specified for the AP50 technology smelter project, however the mitigation measures remain appropriate. 5.5.2 Pollution Control Capacity

5.5.2.1 COMMISSIONING

Management and mitigation activities to minimise the impact of fluoride emissions during commissioning need to focus on minimising the number of open pots. The recommended commissioning process is that two to four pots will be operated without hoods every 48-hours during the start-up period, at a rate of 10 pots per week. This routine should be strictly adhered to in order to minimise the number of pots that are open simultaneously. The proposed Coega Aluminium Smelter project (AP35 technology) will have an additional potline, therefore this recommendation in terms of commissioning takes on added significance. 5.5.2.2 NORMAL OPERATIONS

The World Bank Pollution Prevention and Abatement Handbook for aluminium manufacturing (World Bank, 1998) lists key production and control practices that would lead to compliance with




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emission guidelines. The emissions from the proposed Coega Aluminium Smelter project comply with the emission requirements specified by the World Bank. 5.5.2.2.1 GTC and FTC

The AP50 technology smelter project proposed to use the dry scrubbing system that uses alumina as the adsorbent for the gaseous fluoride emissions from the reduction pots and anode-baking furnace. This allows for the recycling of fluorides within the system. Particulates are removed in a bag-filter, a treatment technology that is recommended by the World Bank (World Bank, 1998). The abatement equipment uptime for fluorides on the GTCs and FTC is extremely high, approaching 100%, due to the modular design of the equipment and its redundancy capacity. This means that the abatement equipment will not be operational for potentially a very short period of time. Although a sophisticated level of emission abatement technology is planned for the proposed Coega Alumininium Smelter project, it remains important that it is regularly monitored and serviced to ensure a continued high level of operation. It is recommended that all these mitigation measures are implemented for the proposed Coega Aluminium Smelter (AP35 technology) Project which will utilise identical technology to the AP50 smelter for the GTCs and FTCs 5.5.2.2.2 Pot hoods

The pot hooding is very effective in capturing fluoride emissions. It is therefore important that pot hoods are removed as little as possible. In addition, it is important to ensure that the hoods seal well and damaged hoods are replaced immediately. 5.5.2.2.3 Anode effects

PFCs are formed during anode effects, therefore the control and prevention of anode effects assumes importance in addition to obviating the need to open the hoods. The strategies adopted to minimise PFC emissions include:

• Work on standardising the measurement of PFCs. • Employee training in preventing anode effects. • Research into all aspects of anode effects. • Better monitoring of reduction cell conditions leading to either prevention or rapid

termination of anode effects. The effort to minimise PFC production, by minimising anode effects, has several generally beneficial side effects, namely:

• Increased anode consumption during the anode effect is prevented. • Power consumption is reduced. • Melt conditions stay closer to optimum, and fluoride emissions are reduced.




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In light of the concerns surrounding greenhouse gases, there is a need to quantify PFC emissions from the smelter, particularly C2F6. It is recommended that all these mitigation measures are implemented for the proposed Coega Aluminium Smelter (AP35 technology) project. 5.5.2.2.4 SO2

Ambient SO2 concentrations resulting from the proposed Coega Aluminium Smelter project are generally low when compared with guideline values. There are no stack abatement measures proposed for SO2 emissions. It is planned to use petroleum coke with a sulphur content 3%. Petroleum coke with lower sulphur content can be considered as a method to reduce SO2 emissions. 5.5.3 Monitoring

Air quality and meteorological monitoring is currently conducted at three stations in the Coega IDZ (i.e. Hougham Park, Amsterdamplein and Motherwell) by C&M Air Pollution Consultants on behalf of the Coega Development Corporation. Meteorological monitoring is also done at two other stations by CSIR on behalf of the National Ports Authority. Collectively this data provides a comprehensive meteorological data set for the area for climatology purposes and as data to support air pollution studies. It is fundamentally important that this network of meteorological stations is supported. Currently the air quality monitoring is limited to SO2, PM10 and TSP. It is important that this capability is expanded to include both gaseous and particulate fluoride at the three stations. This additional monitoring capability will provide the data required to evaluate the representativeness of model predictions. It will also be critical input to the validation of surface water, vegetation and other impact studies. It is important to build on current competency, capacity and infrastructure. The current air quality-monitoring network provides an ideal technical capacity and infrastructure platform on which to build that additional air quality monitoring requirement. Opportunities need to be explored on how best to capitalise on these existing skills in expanding the network. Ambient monitoring for fluoride should commence before the plant is commissioned. The approval of the permits to operate scheduled processes is dependant on the proponent demonstrating that the best practicable technology for preventing or reducing emissions of noxious or harmful gases to the atmosphere will be adopted. The permit requires routine reporting of agreed emission rates as input to the National Emissions Inventory for scheduled processes. To this end, it is necessary that Alcan continually exercises a high degree of awareness of their emission performance. The details of the emission monitoring strategy will be finalised at the time of permit negotiation.




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The basic measure of fluoride emission performance is expressed as kgF/tAl. Some methods have been developed within the aluminium industry that physically measures gaseous and particulate fluoride emissions at the potroom roof vents, GTC stacks and the FTC stack. Of these the US-EPA methods are the best known. Ideally, monthly monitoring of potroom roof vent fluoride emissions needs to be done, according to an accepted methodology. In addition, monthly monitoring of GTC and FTC fluoride emissions need to be conducted. SO2 emission rates are stable in relation to metal production rates (the primary source being consumption of anodes, directly related to metal production), and should be computed on a monthly basis using a mass balance approach. These calculations should be confirmed on a quarterly basis on the major SO2 emission sources (GTC, FTC and casthouse stacks) during the initial years of operation. Quantification of other air emissions such as PAH, total particulates, PM10, CO2, CF4 and C2F6 should be undertaken. PM10 will be quantified by measurement, while CO2 will be calculated using mass balance. In the case of CF4 and C2F6 these concentrations will be calculated using the methodology in the IPCC/OECD/IEA Guidelines for National Greenhouse Gas Inventories. There is a growing global database of emission factors associated with the aluminium industry smelting which will be referenced for reporting purposes. It is recommended that all these monitoring measures are implemented for the proposed Coega Aluminium Smelter (AP35 technology) Project.

5.6 CONCLUSIONS The air specialist review study has considered the impact of air emissions between the 485 000 t/a AP50 technology aluminium smelter and the proposed AP35 technology aluminium smelter at Coega (considering both a base case of 660 00 t/a and an upside case of 720 000 t/a). The review has been conducted using the output of dispersion modelling using the CALPUFF model for a health risk assessment, particularly for sulphur dioxide, fluoride (gaseous and particulates) and polycyclic aromatic hydrocarbons. Other pollutants have been assessed qualitatively and these include total suspended particulates, carbon monoxide and dust. The extent of pollution dispersion has been illustrated using isopleth maps and more specific concentrations at receptor points have been used in assessing the risk to health. The receptors used in the study are Motherwell, Bluewater Bay, Sundays River Mouth, Port Elizabeth, Coega harbour, Addo Heights and the proposed smelter site. The results of the review indicate that the proposed Coega Aluminium Smelter (AP35 technology) will result in higher ambient concentration of air pollution. However, for the two main pollutants of concern, namely sulphur dioxide and fluoride, no acute or chronic health effects are expected in any healthy or sensitive individual. For SO2, no adverse health effects are expected even when the cumulative concentrations of SO2 from the current and proposed emissions are taken into account. The approach of assessing SO2 and HF as a mixture (even though they have




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different mechanisms of action) has been used in this study as a further precaution and the results indicate that acute respiratory effects from the proposed smelter remain highly unlikely. SO2 emissions from the smelter will contribute in a small way to the formation of acidic droplets and aerosols over the region. These, in turn, may precipitate out over the area where they form, but they may also be transported out of the immediate area and precipitate elsewhere in time. Acid deposition will more likely have a greater impact on the Mpumalanga highveld where the electricity which will be used is generated. This aspect, however, is not within the scope of this study. Similarly, although greenhouse gas emissions from the smelter are relatively small and contribute ~0.5% to South Africa’s total CO2 emissions, the CO2 emissions from power generation will be larger (~4% of Eskom’s total and 2.2% of South Africa’s CO2 emissions). The significance of the potential impact of total suspended particulates on human health is low, even when one assumes that the particles are 100% respirable which is unlikely. Carbon monoxide emissions from the proposed Coega Aluminium Smelter will not have an impact on health. There is unlikely to be an odour impact from the proposed smelter. Although fluoride deposition rates are low, negative impacts in ecological receptors could occur in the IDZ, or further afield. Polycyclic Aromatic Hydrocarbons (PAH) are emitted by the smelter and although it is not known what the constituents are, benzo(a)pyrene has been modelled and assessed as there is concern about its carcinogenic properties. The results of the assessment show that the risk of developing cancer from exposure to this pollutant is low. Dust generated during the construction phase, particularly the early excavation period may have a nuisance impact beyond the immediate region under windy conditions. Management measures to minimise or mitigate the impact will be implemented. Based on a comprehensive air quality modelling exercise, using the best available input data, and a health risk assessment, it is apparent that impacts from emissions from the proposed Coega Aluminium Smelter are limited to the immediate area surrounding the plant. They will however persist for the lifetime of the plant, but the intensity of the impacts are low, with and without mitigation

5.7 RECOMMENDATIONS 5.7.1 Monitoring

• Continue and support the existing meteorological monitoring in the area. • Continue and support the existing pollution monitoring programme in the area. • Monitor fluoride deposition, prior to and after the plant is commissioned,

especially with a view to validating the model results.




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• Ambient monitoring of fluoride should commence before the plant is commissioned.

• A programme for emission monitoring and reporting must be implemented. 5.7.2 Construction

• Remove only limited vegetation to accommodate construction activities. • Spray unpaved site roads and access roads with water routinely throughout

construction to contain dust. Water (possibly sea water) can be used as a wetting or binding agent on the unpaved roads and terraces.

• Implement traffic control measures to limit vehicle-entrained dust from unpaved roads e.g. by limiting vehicle speeds and by restricting traffic volumes.

• Use a motorised sweeper or vacuum vehicle on surfaced roads, to reduce the presence of sand.

• Re-vegetate construction terraces once all of the construction is completed, and when the laydown area is vacated.

5.7.3 Commissioning and Operations

• Minimise the number of open pots during commissioning and operations. • The abatement equipment must be regularly monitored and serviced to ensure a

continued high level of operation. • The pot hooding must be removed as little as possible. • Ensure that the hoods seal well and damaged hoods are replaced immediately. • Train employees in preventing anode effects. • Better monitoring of reduction cell conditions leading to either prevention or rapid

termination of anode effects. 5.7.4 Further Studies

• In light of the concerns surrounding greenhouse gases, there is a need to quantify PFC emissions from the smelter, particularly C2F6.

• Conduct vegetation / flora baseline monitoring to better understand the potential effects of atmospheric emissions on plants; and continue this monitoring during the operation of the proposed smelter.

• Quantify other air emissions such as PAH, total particulates, PM10, CO2, CF4 and C2F6 through periodic measurement programs to establish emission factors associated with the process. There is a growing global database of emission factors associated with the aluminium industry smelting which should be referenced for reporting purposes.

• Investigate the various mechanisms included in the Kyoto (and Marrakech) protocol which specify ways in which companies can help to reduce greenhouse gas emissions.




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5.8 REVIEW OF IMPLICATIONS FOR THE RECORD OF DECISION In terms of the listed activities that will require the issuing of a scheduled process permit, there have been no changes. South African legislation with respect to air quality is currently undergoing significant revision. In future all industries will have to apply for atmospheric emission licences. In the interim, the Coega Aluminium Smelter will be required to make an application to the local CAPCO (Chief Air Pollution Control Officer) for a scheduled process registration certificate. Discussions with the Chief Directorate of Air Quality Management and Climate Change of the national Department of Environmental Affairs and Tourism (DEAT) in July 2005, confirmed that the air permit can be issued based on the draft air permit that was prepared for the proposed smelter in 2003, taking into account the technology changes presented in this report (R. Mabalane, DEAT, pers comm. 11 July 2005). It is recommended that Condition 8.5.21 is removed from the ROD since this has incorrectly quoted ambient air quality concentrations as the proposed minimum emission standards for the proposed development. It is recommended that this clause is replaced with a statement that requires the proponent to comply with the World Bank emissions standards for aluminium smelters listed below. The proposed development is designed to comply with these standards.

World Bank Emission Standards for Aluminium Smelters

Pollutant Emission Standard (kg/t Al) Total Fluoride 0.6 Dust 1.0 PAH 0.02 Tar 0.04 Carbon dioxide 1.8 Carbon tetrafluoride 0.1 Sulphur dioxide 1.0

It is also recommended that Clause 8.5.6 of the ROD be modified. This clause currently states that the sulphur content in petroleum coke used at the smelter may not exceed 3% w/w. Since completing the Final EIR in 2002, the global availability of petroleum coke with low sulphur content has reduced dramatically. It is therefore recommended that this clause be changed to require that the smelter use petroleum coke with “the lowest possible sulphur content commercially available” and not state a maximum % w/w (weight per weight).

Documents

Air Quality and Human Health - CSIRfred.csir.co.za/project/smelter/report/Ch5_Air.pdf · Air Quality and Human Health ... and the World Bank. ... According to the World Bank Pollution