Freeport

- McMoRan Copper & Gold Inc. (FCX) Engineering Report Miami Smelter Expansion Project Engineering Management H377000 Extended Roofline SO2 Emissions Summary

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# Table of Contents

1. Introduction

................................ ................................ ................................ ................................ ........... 1

2. Summary and Conclusions

................................ ................................ ................................ ................. 1

3. Extended Roofline Study (ERS) Assessment Methodology

................................ ............................ 2

3.1 Sampling Locations and Areas

................................ ................................ ................................ ..... 2
3.2 Sampling Period

................................ ................................ ................................ ............................ 7
3.3 Data Filters

................................ ................................ ................................ ................................ .... 7
3.4 Isa 2 Temperature Approximation

................................ ................................ ................................ 8
3.5 Gas Flow Rate

................................ ................................ ................................ .............................. 9 3.5.1 Anode Aisle Flow Approximati on

................................ ................................ ..................... 9
3.6 Throughput Adjustments

– Annualized Emissions

................................ ................................ ..... 10
3.7 Weighting Factor for Unequal SO 2 

### Concentration from Each Sample Point

.............................. 11 3.7.1 Simplified vs. Concentration Weighted Approach

................................ ......................... 12

4. Results

................................ ................................ ................................ ................................ ................. 13

4.1 SO 2 

### Concentration

................................ ................................ ................................ ...................... 13

4.2 Hourly vs. Minute SO 2 

### Data

................................ ................................ ................................ ........ 14

4.3 Mass Emissions

................................ ................................ ................................ .......................... 14

**List of Tables**

Table 2

- 1: Comparison of the 2013 ERS and June 2012 SO 2 

### Gas Sampling Campaigns

.......................... 2 Table 3

- 1: Key Dimensions for 2013 Extended Roofline Study (ERS)

................................ ......................... 3 Table 3

- 2: Sampling Period

................................ ................................ ................................ ........................... 7 Table 3

- 3: Plant SO 2 

### Emissions and Throughput during 2013 Ext ended Roofline Study (ERS)

............... 11 Table 3

- 4: Annual Plant Throughput Basis

................................ ................................ ................................ . 11 Table 3

- 5: Simplified vs. Concentration Weighted SO 2 

### Emissions Calculation Results

............................. 13 Table 4

- 1: SO 2 

### Concentrations from Extended Roofline Campaign

................................ ........................... 13 Table 4

- 2: Comparison Between Minute

- by

- Minute and Hourly SO 2 

### Data

................................ ................. 14

**List of Figures** Figure 3

- 1: Gas Sampling Locations, Converter Aisle

................................ ................................ .................. 4 Figure 3

- 2: Gas Sampling Locations, Anode Aisle

................................ ................................ ....................... 4 Figur e 3

- 3: Gas Sampling Locations, IsasmeltTM Building

................................ ................................ ............ 5 Figure 3

- 4: Gas Sampling Locations, Electric Furnace Building

................................ ................................ ... 6 Figure 3

- 5: Monthly Average Temperature Rise for the Isa 2 Monitoring Location

................................ ...... 8 Figure 3

- 6: Monitor Mounted Wind Speed Impeller

................................ ................................ ...................... 9 Figure 3

- 7: Monthly Trends in Building Flow Rates

................................ ................................ .................... 10Freeport

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© Hatch 2014/03 

# 1. Introduction

Freeport

- McMoRan Copper & Gold Inc. (FCX) is undertaking a project at their Miami copper smelter in Arizona to increase production capacity and to ensure the smelter’s operation does

not cause or cont ribute to a violation of the new National Ambient Air Quality Standard (NAAQS) for Sulfur Dioxide of 75 ppbv (1

- h).

T he Feasibility Study SO 2 

### mitigation scope and current permit application are based on a

3

- 4 day sampling campaign completed in June 2012

. Results from t he June 2012 Roofline
Sam pling Campaign methodology were summarized in detail in the Feasibility Study Report:
H341001

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- 0003 ( Rev. 0) Building Scrubber Sizing Study. To mitigate compliance and capital cost risks associated with the June 2012 roofline sampling campaign, the
extended roofline sampling (ERS) campaign was initiated by FCX in late 2012 to provide more representative, long term roofline SO 2 

### emission estimates for current operation. Gas
flow measurements for most smelter buildings started in mid March 2013; mass emissions estimated for the ERS campaign in this report correspond to a period of roughly 9 months

. This represents almost 100 times more data than the June 2012 campaign.

This report summarizes the annualized SO 2 

### mass emissions and calculation approach for the current Miami smelter operation based on results obtained from the ERS campaign up to December 31, 2013. The annualized SO 2 

### emissions representing current operation are compared to the results based on the J une 2012 sampling campaign , which was used to establish the Feasibility Study SO 2 

### mitigation scope.



# 2. Summary and Conclusions

Annual ized SO 2 

### emissions representing a current normalized throughput equivalent to roughly 689,000 dstpy of new metal bearing mat erials (NMBM) are summarized for the ERS campaign in Table 2

- 1 . The ERS campaign involved sampling SO 2 

### , temperature and velocity from the following four smelter buildings; Anode Aisle (AA), Converter Aisle (CA), Isasmelt Building (Isa) and Electric Furnace Building (ELF). T hese emissions are compared directly
with the annualized results obtained based on t he June 2012 sample campaign, which were used to establish the Feasibility Study SO 2 

### mitigation scope.

The results indicate generally good alignment of annualized emissions estimated based on the ERS campaign compared with results from June 2012. Total ann ualized SO 2 

### emissions are lower by approximately 20%. Annualized emissions are substantially lower than June 2012 for the Isa building (55% lower) and CA (20% lower). ELF building emissions are roughly 50 % higher, and AA emissions are approximately 20% hig her. The increase in AA emissions is attributed primarily to a revision in the measured roof monitor width from 4.0 ft to 4.5 ft. The results for the other smelter buildings are consistent with SO 2 

### concentration (only) data obtained from the full ERS perio d to date, covering a larger data period spanning almost 13 months from December 2012 through December 2013.Freeport

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© Hatch 2014/03 Table 2

- 1 : Comparison of the 2013 ERS and June 2012 SO 2 Gas Sampling Campaigns

Area Total Annual ized Emissions

stpa

June 2012 Sampling Campaign 2013 Extended Roofline Campaign

A node Aisle (AA) 160 193
Converter Aisle (CA) 425 343

Isa smelt Building (Isa) 239 106

E lectric Furnace Building (ELF) 35 53

**Total 859**  **695**



### The impact on expected plant emissions and the corresponding SO 2 

### GLC for the future operation with the proposed mitigation scope in place is expected to be a minor reduction . An appropriate design factor will be included to account for sampling variability and unmeasured
emissions from other building openings (e.g., 20% was used in the Feasibility Study).

Sampling methodologies are detailed in the report. Changes from the June 2012 sampling methodology are highlighted. These are generally minor.

A simplifi ed calculation approach based on average combined SO 2 

### concentration for each building was found to give similar results to a more complex approach in which the SO 2 

### concentration from each individual sample point was estimated based on temperature relative to ambient. The results above are based on this simplified calculation approach, which will prove easier to implement automatically in the FCX Miami control system

.



# 3. Extended Roofline Study (ERS) Assessment Methodology

The sampling procedure for the 2013 ERS was carried out in generally the same fashion as the June 2012 campaign. FCX has been responsible for setting up and running the ERS campaign. The following sec tions will expand upon and identify deviations from the June 2012 methodology.



## 3.1 Sampling Locations and Areas

Figure 3

- 1 to Figure 3

- 4 illustrate s the smelter building gas sampling locations

, with indication of proximity to major process vessels. No adjustment was made in this report to account for

un measured fugitive emissions. Table 3

- 1 and the corresponding calculations for the 2013 ERS reflect the latest data, including several updated roof monitor dimensions. All roof monitors are assumed to extend the full length of each building. The width reflects the bottom
of the roof monitor opening, which is located at approximately the same location where the gas velocity is measured.Freeport

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© Hatch 2014/03 Table 3

- 1 : Key Dimensions for 2013 Extended Roofline Study (ERS)

Sample Point Length (ft) Width (ft) Height (ft) Notes

Converter Aisle (CA) CA 2 **165** 8

- Column line 20 to 26 CA 3 **55** 8

- Column line 26 to 28 CA 4 **55** 8

- Column line 28 to 30 CA 5 (high bay) **55 4.5** 

- Column line 30 to 32. 4.5 ft wide roof monitor (vs. 8

ft opening) added after June 2012 sampling. Anode Aisle (AA)
AA 1 **149 4.5** 

- AA Column Line 11 to AA Column Line 18
AA 2 **84 4.5** 

- AA Column Line 7.5 to AA Column Line 11 AA 3 (Mold Barrel) **154 4.5** 

- CA Column Line 32 to AA Column Line 7.5
Isa smelt Building (Isa) Isa 1 (crane bay) 45

- 8.6

- Isa 2 (roof monitor) 53.7 **1.7**

- - Isa 3 (WHB opening) 33.2

- 25.4 Assumed 10% reduction in area for WHB, platforms, etc.
E lectric Furnace Building (ELF) ELF 1 (long monitor) 54 8

- ELF 2 (short monitor) 13.3 8

-

NOTE: **Bold highlighted values** have been updated since June 2012 sampling.



### A few updates relative to the June 2012 sampling campaign are highlighted below:



### • There was no AA C rane B ay sampling location since the June 2012 sampling confirmed this to be a negligible SO 2 

### emission source.



### • The ELF building had two total sample locations ( one in the long monitor ) , as opposed to
three total (two in the long monitor) in the 2012 campaign.



### • Elimination of one AA measurement location and relocation of several sampling locations
in the CA , with the updated locations shown in Figure 3

- 1 and Figure 3

- 2

. FCX is now

m easuring in the “hot spots” above each converter vessel , which could increase the

measur ed SO 2 

### concentrations and gas flows relative to the “average” locations
established in June 2012. This is considered conservative.



### • Thermocouples were located at each SO 2 

### sample location. An assessment with the June 2012 results confirmed negligible corrections to the estimated SO 2 

### emissions with additional thermocouples mounted between sample locations.



### • There are no velocity measurements available for the AA since the hi gh peak gas temperatures (well above 200°F) reportedly melted the plastic anemometer impellers shortly after installation

. See Section 3.5.1

.Freeport

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© Hatch 2014/03 Figure 3

- 1 : Gas Sampling Locations, Converter Aisle

Figure 3

- 2 : Gas Sampling Loc ations, Anode AisleFreeport

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© Hatch 2014/03 Figure 3

- 3 : Gas Sampling Locations, IsasmeltTM BuildingFreeport

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© Hatch 2014/03 Figure 3

- 4 : Gas Sampling Locations, Electric Furnace BuildingFreeport

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## 3.2 Sampling Period

SO 2 

### concentrations were taken on a minute

- by

- minute basis starting in December 2012 and continued until December 2013. However, hourly average data was only available for gas flow (velocity) and temperature, along with SO 2 

### , beginning part way through March un til December 31, 2013, reporting direct to the plant control system. Both flow and concentration are required to calculate mass emissions (e.g. stpa or lb/h SO 2 

### ). In general, calculations were applied to the data obtained from Apr il 1, 2013 through Decembe r 31, 2013. Refer to Table

3

- 2 and the text below.

Table 3

- 2 : Sampling Period

Building Period Total Production Days Valid Sampling

Days* Notes

CA Apr. 1 to Dec. 31 , 2013 235 234 Exclude s Oct. 10 to Nov. 19.
AA Apr. 1 to Dec. 31 , 2013 275 256 Isa Apr. 1 to Dec. 31 , 2013 275 256 ELF May 1 to Dec. 31 , 2013 245 245 No flow data until May.

* Note: This reflects removal of invalid data points, see Section 3.3

. 

### Data obtained during March was excluded for all buildings. This was the first (partial) month for which flows were measured. It took some time to get the sampling program up and running smoothly.

For the ELF, data for April was excluded as well. No velocity data was available for this building during March and April.

October 10 th



### – November 19 th 

### (inclusive) was excluded from all Converter Aisle calculations. Several probes were moved during this period to a location directly over Converter #2 in order to assess performance of the new mouth cover. Towards the end of this period the probes were returned to their original locations.

There were also missing temperature measurements for the Isa roof line monitoring location for a portion of the period. See Section 3.4

. 

## 3.3 Data Filters The methodology for treating negative SO 2 

### concentration readings from the monitors is to round them up to zero, as they are assumed to be drift errors or noise. This treatment method
is modestly more conservative than what was used in 2012, where negative concentrations (typically small negative values) were used directly in calculations.

Over the extended campaign in particular, there were ranges of “invalid” sampling data that were filtered from the data set, as fol lows:

**•** Any data obtained during the calibration periods was eliminated from the averaging period (identified by the value “6999.0” in the concentration field or manually input as “CAL” by FCX).Freeport

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### • Any data reporting orders of magnitude lower or higher flow tha n the remainder of the data set was eliminated from the averaging period. Flow changes from the roof monitors are typically modest.

**•** Any data specifically labeled by FCX or the data acquisition system as “No Data” or “No
Good Data for Calculation” was elimi nated from the averaging period.



## 3.4 Isa 2 Temperature Approximation The missing temperatures for the Isa 2 location during April and May were calculated by assuming that the temperature rise, compared to ambient temperature, is equal to the average temperatur e rise during July

- December 2013, 28.4°F, see Figure 3

- 5 . June 2013
was exclud ed from the averaging period since it was deemed non

- representative due to the plant shutdown. This average temperature rise is consistent with the temperature rise of 27°F reported in the 2012 sampling campaign. The impact of temperature on estimated SO 2 

### mass emissions is minor; a 5°F change in tempera ture impacts the mass emissions by roughly 1%.

Figure 3

- 5 : Monthly Average Temperature Rise for the Isa 2 Monitoring LocationFreeport

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## 3.5 Gas Flow Rate Actual ventilation gas velocity from the smelter buildings was es timated using a wind speed impeller at each sample location (as shown in Figure 3

- 6 ). The velocity for each building opening or section of the converte r/anode aisle was multiplied by the corresponding area ( Table 3

- 1 ), then converted to scfm using the measured temperature. The total flow per building (in scfm) was ca lculated as the total flow from all openings (2

- 4, depending on the smelter building). For the converter and anode aisle this represents a more detailed approach than June 2012, where average velocities calculated from 3

- 4 sample locations were multiplied by the total roof monitor open area. Unlike the June 2012 campaign, this modification was required for the 2013 ERS campaign in order to accurately weight the total flow contribution from significantly different roof monitor open areas, notably the differe nt length between sample locations along the aisle.

It has been assumed that a ll vertical gas velocity measurements apply to each section over the applicable area ( length x width) of the monitor. For h orizontal ventilation windows (Isa building only), a velocity profile was taken in June 2012 over the accessible area using a hand held wind speed impeller in order to correct the velocity readings

. The same 62% correction is assumed to apply for the ERS campaign, accounting for the Is a east/WHB window (Isa 3) geometry and flow distribution. Per June 2012, no correction was applied to the Isa crane bay window (Isa 1)

– this location is much closer to the cente r line elevation.

Figure 3

- 6 : Monitor Mounted Wind Speed Impeller



### 3.5.1 **Anode Aisle Flow Approximation** There are no Anode Aisle (AA) velocity measurements available for the ERS campaign. One approach would be to assume the same fixed flow measured during the June 2012 campaign. However, ba sed on flow trends established for the other 3 smelter buildings during the 2013 ERS campaign (see Figure 3

- 7 ), there is a significant seasonal trend in building
exhau st flow for the current operation, with higher flows measured in the colder months, and lower flows measured in the warm summer months such as June. As a result, it is desirable to adjust the AA flows measured in June 2012 . The CA is directly connected to the AA and was deemed to be the most appropriate measurement to scale off, as it is impacted by similar
factors and sources.Freeport

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### Results from June 2012 indicate that average total AA flow (in scfm) is roughly 5% lower than average converter aisle flow (scfm). These have been corrected to account for minor updates to roof monitor dimensions (see Table 3

- 1 ) and average velocities measured in June 2012.
To fol low the variation in flow measured for the CA during the ERS, this ratio was assumed to
be fixed to estimate AA flows.

Figure 3

- 7 : Monthly Trends in Building Flow Rates



## 3.6 Throughput Adjustments

– Annualized Emissions The calculation of annual emissions for current operation requires a method to normalize emissions based on throughput during the applicable sampling period. Key operating variables impacting SO 2 

### emissions were established for the J une 2012 sample campaign. The same parameters were calculated for the 2013 ERS campaign period, as summarized in
Table 3

- 3

. To account for <100% valid SO 2 

### mass emissi on sampling data within this period for most smelter buildings (see Table 3

- 2 ) , a factor was applied to represent the throughput corresponding to the estimated SO 2 

### emi ssions during the period, in order to accurately
estimate mass emissions of SO 2 

### per s hort ton of throughput. For example, if 95% of the data over the 275 day full anode aisle sample period is valid, the equivalent number of good anodes produced is 144,779 st (152,399 x 95 %). This avoids assuming that all missing data

was 0 lb/h SO 2

.Freeport

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© Hatch 2014 All rights reserved, including all rights relating to the use of this document or its contents. Table 3

- 3 : Plant SO 2 Emissions and Throughput during 2013 Extended Roofline Study (ERS)

Area SO 2 Production Sampling Period Total During Sampling Period, Throughput Scaling Parameter

**ppm Days**  **Parameter Value**  **Unit**
AA 8.59 275 Good anodes produced 152,399 st CA 12.39 235 ELF matte 198,590 st Isa Building 14.46 275 Isa feed (NMBM) 507,061 st ELF Building 8.18 245 ELF matte and ELF slag 453,050 st



### Over a complete year of operation, the mass emissions of SO 2 

### are expected to scale from total emissions measured during the test period based on the annual throughput. For a typical annual throughput of 689,000 dstpy of new metal bearing materials (NMBM), consistent with the Feasibility project design criteria, the annual throughput of each scaling parameter is
summarized in Table 3

- 4

. The net adjustment factor is also shown, reflecting the annual throughput divided by the total throughput during the sample period and the % of data over this period that is valid. The same proportion is multiplied by the total SO 2 

### measured from each building over the ERS to calculate annualized emissions at a plant throughput of roughly 689,000 dstpy NMBM.

A factor of 1.0 corresponds to a full year of valid sampling data, a factor of 2.0 corresponds to half a year of sampling data. In general, the valid data summa rized in this report represents

7

- 9 months of valid sampling data, depending on the smelter building. This represents almost 100 times more sample data than the June 2012 campaign.

Table 3

- 4 : Annual Plant Throughput Basis

Area Annual Throughput Net Adjustment Factor

Parameter Value Unit Annual SO 2 / total measured SO 2 (st)

AA Good anodes produced 187,36 5 st 1.3 2

CA ELF matte 322,419 st 1.63
Isa Building Isa feed (NMBM) 688,796 st 1.46
ELF Building ELF matte and ELF slag 748,399 st 1. 65



## 3.7 Weighting Factor for Unequal SO 2 

## Concentration from Each Sample Point For each building there is only a single combined SO 2 

### concentration measurement, reflecting equal flows extracted from 2 to 4 separate locations. In the absence of SO 2 

### concentration measurements from each sample location, there are two possible approaches to calculate
SO 2 

### emissions using the single SO 2 

### conce ntration measurement.Freeport

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### One approach is to ignore any differences in SO 2 

### concentration at the individual sample
locations a nd multiply the blended average concentration measured for each building by the calculated flow (in scfm) for each section (discharge area) of that building. This is referred to herein as the “simple” approach.

The second is to estimate the different SO 2 

### concentrations from each sample location and multiply by the flow measured for that section of the building. Velocity and temperature are the only parameters measured at each individual location. Velocity through the roof monitor is a possible proxy for SO 2 

### concentration and was used to assess the June 2012 results but is impacted by other factors, including building height and roof moni tor dimensions (i.e., narrower opening or higher roof monitor = increased velocity regardless of contaminant concentration). With dimension changes and movement of sampling locations in the 2013 ERS, velocity was no longer deemed to be a good proxy. As a r esult, it is not relevant to compare the relative adjustment factors applied in the June 2012 and 2013 ERS sampling campaigns.

Temperature rise above ambient is believed to be a more reasonable proxy for contaminant concentrations within a given building as most sources of SO 2 

### also release significant heat into the buildings. For example, if the temperature rise is 40°F above ambient at location 1 and 20°F above ambient at location 2, the SO 2 

### concentration at location 1 is assumed to be
double as well.

Data f ilters were set to round up to zero for the contribution from locations where the sample temperature was less than ambient. This scenario would realistically correspond with little or

no SO 2 

### emitting activities below in the aisle so it has a small im pact on the calculations.

Another data filter was applied when the average temperature from all sources combined was less than ambient. For these situations, where there is typically very low SO 2 

### as well, the simple calculation approach was used without a ny attempt to weight the relative contribution from each sample point. This is thought to be a more conservative approach than assuming

no SO 2 

### emission for the combined gas stream.

**3.7.1 Simplified vs.**  **Concentration Weighted Approach** 
Table 3

- 5 summarizes the results for each building using the Simplified and Weighted adjustment calculation approaches. These correspond to mass emissions over the approximately 9 month sample pe riod; they have not been normalized to annual emissions. Over the extended sampling period, the simplified calculation approach aligns very well with the more complex concentration weighted calculation approach. Based on these results, the simple calculati on methodology is the recommended basis for all SO 2 

### results presented in this report and is recommended for future emission estimates

. The design factor used in the project emission inventory (e.g. 20% used in the feasibility study) should be sufficient to capture minor deviations when using the simplified approach.Freeport

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© Hatch 2014 All rights reserved, including all rights relating to the use of this document or its contents. Table 3

- 5 : Simplified vs. Concentration Weighted SO 2 Emissions Calculation Results

Area Sampling Period Total SO 2 lbs Emissions During Test Period

Simplified Adjusted Deviation

AA Apr 1

- Dec 31, 2013 292,578 292,530 100%

CA Apr 1

- Dec 31, 2013 420,661 413,996 98%
Isa Building Apr 1

- Dec 31, 2013 144,790 147,683 102%
ELF Building May 1

- Dec 31, 2013 64,689 70,467 109%

Total

- 922,717 924,675 100%



# 4. Results

4.1 SO 2 

## Concentration Both minute and hourly SO 2 

### concentrations were provided by FCX, though the valid hourly data covers a shorter timeframe (starting in March 2013).

The minute

- by

- minute data was processed over the entire December 2012 to December 2013 sampling period, representing almost 13 months o f data. The resulting average ‘ppm’ concentrations are compared to the concentrations from June 2012 in Table 4

- 1

.
Table 4

- 1 : SO 2 Concentrations from Extended Roofline CampaignFreeport

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### On average the Dec. 2012

- Dec. 2013 SO 2 

### concentrations aligned reasonably well with the June 2012 concentrations, with the exception of the ELF building where the SO 2 

### concentration appears to be high compared to June 2012. The full period average is weighted by the equivalent sampling days each month, which reflects the removal of invalid data , per Section 3.2 and 3.3 (calibrations, equipment maintenance, relocated converter aisle probes for testing of the mouth cover above converter #2, e tc.).



## 4.2 Hourly vs. Minute SO 2 

## Data

In order to calculate SO 2 

### mass emissions , both flow and temperature data are required but were only available on an hourly average basis, along with a second set of SO 2 

### ppm data averaged over the same time frame. A compari son was performed between two SO 2 

### data sets, with both minute and hourly concentration data available, in order to confirm whether or not the hourly data could be used with confidence.

Table 4

- 2 provides a summary of the minute and hourly averaged SO 2 

### data. From the average of the two data sets it is apparent that they correspond well to one another and therefore the hourly averaged SO 2 

### ppm data can be used with confid ence to accurately
reflect the more detailed minute

- by

- minute data. This reduces the massive amounts of data that need to be processed.

Table 4

- 2 : Comparison Between Minute

- by

- Minute and Hourly SO 2 Data



## 4.3 Mass Emissions Annualized results from the 2013 ERS for current operation were presented in Table 2

- 1

, along with the data based on June 2012. Total annualized SO 2 

### emiss ions are lower by approximately 20%. Annualized emissions are substantially lower than June 2012 for the Isa building (55% lower) and CA (20% lower). ELF building emissions are roughly 50 % higher, and AA emissions are approximately 20% higher. The increase in AA emissions is attributed primarily to a revision in the measured roof monitor width from 4.0 ft to 4.5 ft.Freeport

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### The Total Annual ized Emissions (stpa) are based on the simplified calculation approach (no weighting was applied to account for different SO 2 

### concentrations from each sample point). All results over the sample period have been scaled to annual emissions, based on established throughput scaling parameters for each building . The period of valid sampling data for the ERS campaign is almost 100 time s greater than the June 2012 campaign.

There are multiple reasons why the two sampling campaigns do not correlate directly with one another, including:



### • Updated roof monitor length and width dimensions (Section 3.1 ). This includes the calculation of gas flows for individual sections/emission areas within the converter and anode aisle, rather than using average velocities multiplied by the total roof monitor area.



### • Changes in sampling locations (Section 3.1 ).



### • Different data filtering methodologies (e.g., rounding up negative concentration values to 0, see Section 3.3 ).



### • Application of the “simple” average SO 2 

### concentration measured for each building, rather than attempting to weight the SO 2 

### concentration from each sample location based on indicative parame ters such as temperature or velocity (Section 3.7 ).

The impact on expected plant emissions and the corresponding SO 2 

### GLC for the future operation with the proposed mitigation scope in place is expected to be a minor reduction.