## BART DETERMINATION FO R ALCOA INTALCO WORKS FERNDALE, WASHINGTON

Prepared for:

Alcoa Intalco Works Ferndale, Washington

Prepared by:

ENVIRON Corporation 6001 Shellmound Street, Suite 700 Emeryville, California 94608

November 2007

Contract Number 03-8979CIntalco BART Determination FINAL.doc
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## TABLE OF CONTENTS

1.0 INTRODUCTION.......................................................................................................... 1-1

2.0 IDENTIFICATION OF BART-ELIGI BLE UNITS AT INTALCO ........................ 2-1

3.0 BART-ELIGIBLE EMISSION UNIT GROUP DESCRIPTION ............................. 3-1 3.1 P RIMARY 

### A LUMINUM 

### R EDUCTION 

### P ROCESS 

### D ESCRIPTION 

### ........................................ 3-1 3.1.1 E XISTING 

### P OTLINE 

### E MISSIONS 

### C ONTROL 

### ......................................................... 3-2 3.1.2 A NODE 

### B AKE 

### F URNACE 

### E MISSIONS 

### C ONTROL 

### ................................................. 3-2 3.1.3 A LUMINUM 

### H OLDING 

### F URNACE 

### E MISSIONS 

### C ONTROL 

### .................................... 3-3

4.0 BASELINE CONDITIONS AND VISIBILI TY IMPACTS FOR BART-ELIGIBLE UNITS .......................................................................................................................... ... 4-1 4.1 CALPUFF M ODEL AND 

### B ASELINE 

### E MISSION 

### I NPUTS 

### ............................................... 4-1 4.2 S CREENING 

### -L EVEL 

### M ODELING 

### A NALYSIS 

### ................................................................. 4-1 4.3 R EFINED 

### M ODELING 

### A NALYSIS 

### ................................................................................. 4-2

5.0 BART ANALYSIS FOR BART-ELIGIBLE EMISSION UNITS ............................ 5-1 5.1 A VAILABLE AND 

### T ECHNICALLY 

### F EASIBLE 

### E MISSION 

### C ONTROL 

### O PTIONS 

### ................. 5-1 5.1.1 P OTLINE 

### E MISSIONS AND 

### E XISTING 

### C ONTROLS 

### ............................................... 5-1 5.1.2 A NODE 

### B AKE 

### F URNACE 

### E MISSIONS AND 

### E XISTING 

### C ONTROLS 

### ....................... 5-1 5.1.3 P OTENTIALLY 

### A PPLICABLE 

### BART C ONTROL 

### O PTIONS FOR 

### SO 2 

### ..................... 5-2 5.1.4 P OTENTIALLY 

### A PPLICABLE 

### BART C ONTROL 

### O PTIONS FOR 

### PM.................... 5-12 5.1.5 P OTENTIALLY 

### A PPLICABLE 

### BART C ONTROL 

### O PTIONS FOR 

### NO X 

### .................. 5-13 5.1.6 S UMMARY OF 

### T ECHNICALLY 

### F EASIBLE 

### BART C ONTROL 

### O PTIONS 

### ............... 5-15 5.2 C ONTROL 

### E FFECTIVENESS OF 

### F EASIBLE 

### O PTIONS 

### ................................................... 5-17

5.2.1 SO 2 

### W ET 

### S CRUBBING 

### .................................................................................... 5-17 5.2.2 SO 2 

### P OLLUTION 

### P REVENTION 

### ........................................................................ 5-18 5.2.3 A NODE 

### B AKE 

### F URNACE 

### A DVANCED 

### F IRING 

### S YSTEM 

### .................................... 5-18 5.2.4 A NODE 

### B AKE 

### F URNACE 

### L O 

### TO X TM 

### S YSTEM 

### .................................................. 5-18 5.3 E VALUATION OF 

### C OSTS AND 

### O THER 

### I MPACTS 

### ......................................................... 5-18 5.3.1 C OST 

### I MPACTS FOR 

### F EASIBLE 

### C ONTROLS 

### ...................................................... 5-18 5.3.2 E NERGY 

### I MPACTS 

### ........................................................................................... 5-21 5.3.3 G REENHOUSE 

### G AS 

### G ENERATION 

### ................................................................... 5-21 5.3.4 N ON 

### -A IR 

### Q UALITY 

### E NVIRONMENTAL 

### I MPACTS 

### ............................................. 5-21 5.3.5 R EMAINING 

### U SEFUL 

### L IFE 

### ............................................................................... 5-22 5.4 E VALUATE 

### V ISIBILITY 

### I MPACTS 

### .............................................................................. 5-22

6.0 DETERMINATION OF BART.................................................................................... 6-1 6.1 A LUMINUM 

### P OTLINES 

### ................................................................................................ 6-1 6.2 A NODE 

### B AKE 

### F URNACE 

### ............................................................................................. 6-1 6.3 A LUMINUM 

### H OLDING 

### F URNACES 

### .............................................................................. 6-2 6.4 M ATERIAL 

### H ANDLING AND 

### T RANSFER 

### O PERATIONS 

### ................................................. 6-2Intalco BART Determination FINAL.doc
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## TABLES

3-1 Primary Aluminum Reduction Emission Units
4-1 Source Input Data for Baseline Modeling – Point Sources
4-2 Source Input Data for Ba seline Modeling – Line Sources
4-3 Source Input Data for Baseline Modeling – Area Sources
4-4 Source Input Data for Ba seline Modeling – Volume Sources
4-5 Screening Baseline Visibility Modeling Results
4-6 Refined Baseline Visibility Modeling Results
4-7 Culpability Analysis for Refined Ba seline Visibility Modeling Results in Olympic National Park

5-1 RBLC Database Search Resu lts for Primary Aluminum Facilities

5-2 Post Control SO 2 

### Emission Rates
5-3 Summary of Impacts Analysis for SO 2 

### Control Scenarios
5-4 Source Input Data for Post Control SO 2 

### Modeling

5-5 Post Control SO 2 

### Visibility Modeling Results



## FIGURES

5-1 Wet Scrubber Process Flow Diagram



## APPENDICES

A BART Modeling Results

B Business Confidential Information
C Pre-Feasibility Report
D Wet Scrubber Economic and Energy Impact

E Greenhouse Gas Emission CalculationsIntalco BART Determination FINAL.doc
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## ACRONYMS

acfm actual cubic feet per minute AWMA Air and Waste Management Association BACT Best Availa ble Control Technology BART Best Available Retrofit Technology CAA Clean Air Act CFR Code of Federal Regulations DNR Department of Natural Resources dv deciview ELG Effluent Limitations Guidelines ESP Electrostatic Precipitator FGD Flue Gas Desulfurization Intalco Alcoa Intalco Works LAER Lowest Achievable Emissions Rate lb/day pounds per day LSFO Limestone Slurry Forced Oxidation LSNO Limestone Slurry Natural Oxidation MW Megawatt NESHAP National Emission Standard s for Hazardous Air Pollutants NO x 

### Nitrogen Oxides PAH Polycyclic Aromatic Hydrocarbons PM Particulate Matter PM 2.5 

### Particulate Matter less th an 2.5 micrometers in diameter PM 10 

### Particulate Matter less th an 10 micrometers in diameter ppm parts per million ppmv parts per million by volume RACT Reasonably Av ailable Control Technology RBLC RACT/BACT/LAER Clearinghouse SCR Selective Catalytic Reduction SEPA State Environmental Protection Act SNCR Selective Non-Catalytic Reduction SO 2 

### Sulfur Dioxide USEPA United States Envi ronmental Protection AgencyIntalco BART Determination FINAL.doc
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### ES-1

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## EXECUTIVE SUMMARY

The Clean Air Act (CAA) requires the protection of visi bility in 156 scenic areas across the United States. Under CAA Section 169A(b)(2)(A), st ates must require cert ain existing stationary
sources to install Best Available Retrofit T echnology (BART). Alcoa, Inc. – Intalco Works (Intalco) is a “BART-eligible” source. A BART determination is required because Intalco emits air pollutants that may reasonably be anticipated to contribute to impairment of visibility in a
Class I area.

The BART analysis contained herein lists the individual BART-eligible emission units and evaluates visibility impacts, control option f easibility, cost effectiveness and visibility improvement. The BART evaluation was comple ted according to guidance provided in 40 Code of Federal Regulations (CFR) 51, Appendix Y and the Washington, Oregon, and Idaho BART modeling protocol 1



### .

A baseline Class I area visibili ty impact analysis was perfor med on 100 BART-eligible emission units at Intalco using the CA LPUFF model as recommended by the modeling protocol. These sources include three potlines, the anode bake furnace, 12 aluminum holding furnaces, various material handling and transfer operations, natura l gas, diesel and propane combustion sources,
and other small miscellaneous sources.

The modeled or projected 98 th 

### percentile visibility impacts for the entire facility exceed the 0.5 deciview (dv) contribution threshold in five Class I areas: Alpine Lakes Wilderness Area, Glacier Peak Wilderness Area, Mount Rainier Na tional Park, North Cascades National Park, and Olympic National Park. The highest modeled faci lity-wide impact is 1.527 deciviews (dv) in the Olympic National Park (ONP). The modeled visi bility impacts are primarily from the potlines,
with a small amount from the anode bake furnac e. Other sources contribute negligible amounts
to the total as described further below.

The highest modeled or projected 98 th 

### percentile visibility impact of the potlines is approximately 1.44 dv in the ONP. The projected im pacts in the other, more distant, Class I areas are lower. More than 98% of the projecte d impact from the potlines is attributable to emissions from the potroom primary control de vices, with the remainder from the existing potroom roof scrubbers. More than 96% of the potroom primary control device impact is from emissions of sulfur dioxide (SO 2 

### ).

1 Modeling Protocol for Washington, Oregon, and Idaho: Protocol for the Application of the CALPUFF Modeling System Pursuant to the Best Availabl e Retrofit Technology (BART) Regulation. www.deq.state.or.us/aq /haze/docs/bartprotocol . October 11, 2006.Intalco BART Determination FINAL.doc
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### ES-2

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### Results from the BART analysis for potroom em issions determined that BART for potline SO 2 

### emissions is a pollution prevention limit of 3% su lfur in the calcined petroleum coke used to manufacture anodes (i.e., coke ). BART for other pollutants emitted from the potlines [particulate matter (PM) and nitrogen oxides (NO x 

### )] was determined to be the existing level of
emission control.

The highest modeled or projected 98 th 

### percentile visibility impact from the anode bake furnace is approximately 0.053 dv in ONP, with lower projected impacts in other Class I areas. More than 40% of the anode bake furnace impact (0.02 dv) is from SO 2 

### emissions and 55% of the impact (0.03 dv) is from NO x 

### . The analysis of control options for the anode bake furnace determined
that BART for bake furnace SO 2 

### emissions is a pollution preventi on limit of 3% sulfur in the coke. BART for other pollutants em itted from the anode bake furnace (NO x 

### and PM) was
determined to be the existi ng level of emission control.

Additional BART-eligible emission units at th e Intalco facility include aluminum holding furnaces, various material handling and transfer operations, natural gas, diesel, and propane combustion, and other small miscellaneous sour ces that support the primary aluminum ore reduction process. The combined projected imp acts from all remaining BART-eligible emission units (sources other than the potlines and anode bake furnace) are less than 0.05 dv in ONP, with lower projected impacts in other Class I areas. C onsidering the minimal cont ribution to visibility impairment (less than 0.05 dv) and the existing le vel of emissions control, these emission sources
were excluded from further e ngineering analysis and BART wa s determined to be no further
emissions control for these sources.Intalco BART Determination FINAL.doc 

### 1-1 

## 1.0 INTRODUCTION

The Clean Air Act (CAA) requires the protection of visi bility in 156 scenic areas across the United States. Under CAA Section 169A(b)(2)(A), st ates must require cert ain existing stationary
sources to install Best Available Retrofit Tec hnology (BART). A “BART- eligible” s ource is one
that is contained in the 26 identified source cate gories that has the potential to emit greater than or equal to 250 tons per year of any air polluta nt and was put in place during the 15-year interval between August 7, 1962, and August 7, 1977. BART is required when any source meeting this definition emits any air pollutant that may reasonably be anticipate d to cause or contribute to any impairment of visibility in any Class I area.Intalco BART Determination FINAL.doc 

### 2-1 

## 2.0 IDENTIFICATION OF BART-ELI GIBLE UNITS AT INTALCO

Alcoa, Inc. – Intalco Works (Intalco) operates em ission units that fall within the categories of primary aluminum ore reduction plants, one of the 26 identified source categories to which BART is applicable. The Intalco facility was originally constructed in 1965, and began operation in 1966. Therefore, the facility’s em ission units were in existence on August 7, 1977, but were not in operation before August 7, 1962. The facility has the potential to emit greater than or equal to 250 tons/year of sulfur dioxide (SO 2 

### ), nitrogen oxides (NO x 

### ), and particulate matter (PM), all of which have been classified as visibility impairing pollutants. As such, the Intalco facility is defined as a BART-eligible source. All emission units at Intalco, with the exception of one remelt furnace, were constructed between August 7, 1962 and August 7, 1977 and are, therefore, BART-eligible.Intalco BART Determination FINAL.doc 

### 3-1 

## 3.0 BART-ELIGIBLE EMISSION UNIT GROUP DE SCRIPTION

3.1 P RIMARY 

### A LUMINUM 

### R EDUCTION 

### P ROCESS 

### D ESCRIPTION 

### Intalco’s primary aluminum reduction operations include three potlines, an electrode manufacturing operation, consisting of a paste production ope ration and a green anode baking furnace, and miscellaneous material handling operations.

The potline operation manufactures metallic aluminum by the electrolytic reduction of alumina in side-worked prebake cells. Di rect electrical current, passing between anodes and the cathode, electrolytically reduces the al umina to metallic aluminum a nd oxygen. Molten aluminum is deposited and accumulates over time at the cathode beneath a layer of molten cryolite bath. Periodically the molten aluminum is siphoned from beneath the cryolite ba th and processed to achieve specific metal properties or is retained as pure aluminum. The produced aluminum is solidified into intermediate or final products.

Anodes are manufactured in an ancillary on-site paste producti on plant. Calcined petroleum
coke used to manufacture anodes (i.e., coke) is crushed and sized, anode butt material is crushed and sized, and both are mixed toge ther with pitch and formed into self-supporting carbonaceous blocks called “green anodes.” The green anodes are then cured and baked in furnaces before being used in the side-worked pr ebake aluminum reduction process.

Table 3-1 presents the individu al emission units that are incl uded in the primary aluminum reduction emission unit group and that were identifie d as BART-eligible emission units. Potlines A, B, and C emit SO 2 

### and PM, and the anode bake furnace emits lesser amounts of SO 2 

### , NO x 

### , and PM. These emission units are already e quipped with sophisticated emission control equipment for PM, so the BART determination for these emission units focuses primarily on potential reductions for SO 2 

### and NO x 

### .
The remaining emission units identified in Table 3-1 include aluminum holding furnaces, various material handling and transfer operations, natura l gas, diesel, and propa ne combustion, and other small miscellaneous sources that support the potlin es and anode bake furnace. Aside from the natural gas combustion products, emissions from most of the support operations consist of relatively small amounts of PM that are controlled by fabric filter type control devices. Fabric filters effectively remove more than 99% of particulate emissions and, based on the control technology review, represent the best available c ontrol for these types of material handling and transfer operations. The natural-gas fired units at Intalco emit very little PM. Given the relatively low level of emissions, the fact that fabr ic filters represent the best available control, and the minimal impacts of these sources on visi bility, these emission units were excluded fromIntalco BART Determination FINAL.doc 

### 3-2 

### further BART engineering analysis. BART for these support operations was determined to be the existing level of control.

3.1.1 Existing Potline Emissions Control The potlines at Intalco consist of six potroom groups [i.e., “... a group of potroom segments ducted to a common control system” (40 Code of Federal Regulations 60.191)] of electrolytic reduction cells connected in series that pr oduce molten aluminum. There are two potroom groups per potline. Each potroom is comprised of 120 reduction cells (or pots) with 18 anodes per cell. All pots at Intalco are hooded to control emissions. Emissions captured by the hoods are drawn through primary control systems, which consist of dry alumina injection systems with baghouses for the control of PM and fluoride emi ssions. A small fraction of the pot emissions escape capture by the hoods and ar e released inside the potrooms. These secondary emissions are drawn through a secondary control system which consists of wet roof scrubbers that control
PM and fluoride emissions.

Each of Intalco’s primary control system cente rs consists of multi-compartment baghouse cells. Either reverse pulse or reverse flow is used in cleaning the fabric filters of the baghouse cells. The multiple compartment design allows for maintenance and troubleshooting of individual cells while the baghouse center is still operating. The PM control efficiency of the primary control system is estimated to be 97.7% based on measured emissions.

Fugitive potroom emissions from primary alumin um smelters are typically not controlled. However, Intalco operates a sec ondary pollution control system on each of its potlines to abate fugitive emissions. The secondary control system consists of 159 wet roof scrubbers for the three potlines. Each wet roof scrubber treats approximately 10,000 actual cubic feet per minute (acfm) of potroom air. The wet roof scrubbers become inoperable and must be shutdown during any sustained periods of below-freezing temperatur es in order to avoid permanent damage from freezing. These shutdowns occur only in the winter months, and occur infrequently. For the last four operating years, shutdowns due to cold temperatures have averaged less than six or seven days per year. The PM control efficiency of th e secondary control system is estimated to be approximately 82%.

3.1.2 Anode Bake Furnace Emissions Control Products of natural gas combustion, products of combustion from volatiles liberated during the baking of green anodes, and other emissions typically associated with anode baking are exhausted to a dry alumina scrubbing system. The baking furnace emission control equipment conditions the exhaust gases prior to alumina bei ng injected. Fabric fi ltration modules located downstream of the alumina injection re duce PM emissions by as much as 99%.Intalco BART Determination FINAL.doc 

### 3-3 

### 3.1.3 Aluminum Holding Furnace Emissions Control The 12 holding furnaces at Intalco vary in size. The largest of these furnaces has a natural gas rated burner capacity of 22 MMBtu/hr. There are no emissi on controls associated with the
aluminum furnaces at Intalco.Intalco BART Determination FINAL.doc 

### 4-1 

## 4.0 BASELINE CONDITIONS AND VI SIBILITY IMPACTS FOR BARTELIGIBLE UNITS

CALPUFF modeling was performed to evaluate the cumulative visibility impacts of BARTeligible emission units at Intalco, and to compare the relative contribution of individual emission units to the total visibility impact. All mode ling performed in association with this BART determination was done by TRC Environmental Corporation following the WDOE’s BART modeling protocol 2 

### . The complete Intalco BART modeling report is contained in Appendix A

.

4.1 CALPUFF M ODEL AND 

### B ASELINE 

### E MISSION 

### I NPUTS 

### CALPUFF and its meteorological model CALM ET are designed to handle the complexities posed by complex terrain, long source recepto r distances, chemical transformation and deposition, and other issues related to Class I impacts. The USEPA adopted the CALPUFF modeling system as a guideline model for source- receptor distances greater than 50 km and for use on a case-by-case basis in complex flow situat ions for shorter distances (Federal Register, April 15, 2003). CALPUFF was recommended for Class I impact assessments by the Federal Land Managers Workgroup in 2000 and the Intera gency Workgroup on Air Quality Modeling in 1998. CALPUFF is recommended by USEPA (Federal Register, July 6, 2005) and the State of Washington 3 

### for BART analyses.

Tables 4-1, 4-2, 4-3, and 4-4 pr esent the baseline modeling source input data for point sources, line sources, area sources, and volume sources, re spectively, that were used in the CALPUFF model to forecast the visibility impacts. In accordance with Section IV of 40 CFR 51 Appendix Y and the BART modeling protoc ol for Washington, Oregon, and Idaho, baseline emission rates used in the model were based on 24-hour average actual emissions from the highest emitting day.

4.2 S CREENING 

### -L EVEL 

### M ODELING 

### A NALYSIS 

### Screening runs were performed for 2003 th rough 2005 using the 4-km resolution CALMET meteorological data set prepared by Geomatrix for Washington, Oregon, and Idaho. Eight Class I areas (Mount Adams Wilderness Area, North Ca scades National Park, Goat Rock Wilderness Area, Pasayten Wilderness Area, Glacier Peak National Park, Alpine Lakes Wilderness Area, Olympic National Park, and Mount Rainier National Park) were included in the screening level visibility modeling.

2 Modeling Protocol for Washington, Oregon, and Idaho: Protocol for the Application of the CALPUFF Modeling System Pursuant to the Best Availabl e Retrofit Technology (BART) Regulation. www.deq.state.or.us/aq/h aze/docs/bartprotocol.pdf . October 11, 2006.

3 Ibid.Intalco BART Determination FINAL.doc 

### 4-2 

### The screening level analysis results are presented in Table 4-5. These resu lts project visibility impacts within Mount Adams Wilderness Area of less than 0.5 dv, indicat ing that Intalco does not contribute to visibility impairment in the Mount Adams Wilderness Area. A refined, 1-km visibility impact analysis was subsequently performed on the remaining seven Class I areas.

4.3 R EFINED 

### M ODELING 

### A NALYSIS 

### Table 4-6 presents the modeled 98 th 

### percentile total source visibility impacts (reported as deciviews) for 2003, 2004, and 2005 in the seven Class I areas identified in the screening modeling analysis as having visi bility impacts greater than 0.5 dv. Refined modeled visibility impacts exceed the contribution threshold lim it of 0.5 dv at Alpine Lakes Wilderness Area, Glacier Peak Wilderness Area, Mount Rainier Na tional Park, North Cascades National Park, and Olympic National Park. Refined modeled visibility impacts at the Goat Rock and Pasayten
Wilderness Areas were below the 0.5 dv contribution threshold. The highest predicted visibility impacts were in Olympic National Park.

Table 4-7 presents a culpability analysis for Olympic National Park. Individual emission unit visibility impacts in Olympic National Park were used to identify which emission units were forecasted to have the most impact on visibil ity impairment. The modeled or projected 98 th 

### percentile visibility impact from the combin ed potline emissions for the maximum year is approximately 1.44 dv in Olympic National Park. Mo re than 98% of this projected impact from the potlines is attributable to emissions from the potroom primary control devices, with the remainder from the potroom wet roof scrubbers. More than 96% of the potroom primary control device impact is from emissions of SO 2 

### . The modeled or projected 98 th 

### percentile visibility impact for the maximum year from the anode bake furnace was 0.053 dv in Olympic National Park. More than 40% of the anode bake furnace impact is attributable to SO 2 

### emissions and approximately 55% of the impact is from NO x 

### emissions. The total projected impacts from the remainder of the facility’s BART-eligible sources for the maximum year are 0.049 dv in Olympic National Park.

For all emission units other than the potlines and anode bake furnace, the refined modeling
results in Table 4-7 show a combined total visi bility impact that is less than 0.05 dv. The combined impact of these emission units is less than 10% of the facility-wide contribution
threshold level of 0.5 dv for BART a pplicability established for Washington 4 

### . Reduction in
emissions from these units would not result in significant visibility impr ovement in any of the Class I areas. For example, the modeled visibil ity impact from all 12 aluminum holding furnaces (casthouse stacks in Table 4- 7) was 0.004 dv at ONP. The use of added controls for these

4 Modeling Protocol for Washington, Oregon, and Idaho: Protocol for the Application of the CALPUFF Modeling System Pursuant to the Best Available Retrofit Technology (BART) Regulation. October 11, 2006. www.deq.state.or.us/aq/h aze/docs/bartprotocol.pdfIntalco BART Determination FINAL.doc 

### 4-3 

### furnaces would provide a negligible visibility im provement at ONP, as well as the other Class I

areas.

Based on results from the baseline modeling, th e scope of the BART control analysis and engineering cost calculations were focuse d on the potlines and anode bake furnace.Intalco BART Determination FINAL.doc 

### 5-1 

## 5.0 BART ANALYSIS FOR BART-E LIGIBLE EMISSION UNITS

The results of the refined CALPUFF modeling s how that Intalco’s potline reactors and anode bake furnace contribute to visibility impairment in five Class I areas. The BART analysis completed for these emission sources is described in this section. The anal ysis included a review of available and technically feasible retrofit technologies (Steps 1 an d 2), determination of
control effectiveness for feasible options (Step 3), evaluation of cost and secondary impacts for feasible alternatives (Step 4), and analysis of impacts and vi sibility improvements (Step 5).

5.1 A VAILABLE AND 

### T ECHNICALLY 

### F EASIBLE 

### E MISSION 

### C ONTROL 

### O PTIONS 

### Steps 1 and 2 of the BART analysis are to id entify available emission control options and to evaluate the technical feasibility of these cont rol technologies. Contro l options for the potline
reactors and anode bake furnace are descri bed separately in the following sections.

5.1.1 Potline Emissions and Existing Controls Aluminum is manufactured in large electrolytic reduction cells called pots. Aluminum is produced from alumina in the pot as current is passed from a carbon anode to carbon blocks on the pot wall, which serve as the cathode. The anodes are made from pitch and coke. The major pollutants emitted from the cells are PM, hydrogen fluoride, SO 2 

### , and carbon monoxide. PM includes particulate fluoride, ca rbon dust, and alumina. SO 2 

### comes from the sulfur in the components used to make the anodes. NO x 

### emissions are minimal since there is no external fuel or combustion zone and there are no large so urces of nitrogen in the raw materials.

Emissions from the pots are coll ected by close capture hoods over each pot. The hoods enclose the pot as tightly as possible to collect off-gases, but sections ma y be removed to allow anodes to be changed. The off-gases are collected into manifolds that combine the gases from the individual pots. The temperature of the exhaust gases entering the control equipment is typically
150 to 300°F 5 

### . The combined gases are routed to a dr y alumina scrubber. The potline primary control systems for Intalco's three potlines consist of dry scrubbers using alumina injection with
fabric filtration for PM control. The system at Intalco is large, treating approximately 1,815,000 acfm of 180°F exhaust gases.

5.1.2 Anode Bake Furnace Emissions and Existing Controls

The anode bake furnace structure is a series of interconnected refr actory flues connected to side
main exhaust manifolds. The furnace is fueled with natural gas. Exhaust gases are routed so that

5 Air and Waste Management Association (AWMA). 2000. Air Pollution Engineering Manual , Second Edition.Intalco BART Determination FINAL.doc 

### 5-2 

### flue gases preheat the next section to be fired. Flue gases from the anode bake furnace contain PM, hydrogen fluoride, SO 2 

### , carbon monoxide, and hydrocarbons.

The bake furnace control device us ed at Intalco is similar to th e potline primary control system, consisting of dry alumina injection with fabr ic filtration. The bake oven gas stream is conditioned by a water spray to reduce the inlet temp erature before it enters the scrubber. Fresh and recycled alumina are injected into the gas stream, gaseous fluoride and POM are adsorbed onto the alumina surface, and fabric filters on to p of the reactor compartments collect entrained particulate matter present in the gas stream. The system at Intalco treats approximately 216,000 acfm of 205°F exhaust gases.

5.1.3 Potentially Applicable BART Control Options for SO 2 

### Sulfur in the anodes is oxidized, releasing SO 2 

### from the potlines as the anodes are consumed.
SO 2 

### is also released from the anode bake furn ace as pitch used to help form the anodes is oxidized during the baking process. Options for controlling SO 2 

### include both add-on controls and pollution prevention.

5.1.3.1 Add-on Emission Controls Absorption and adsorption have been used for the control of SO 2 

### emissions from numerous power utility and i ndustrial processes. As a result many commercialized control technologies have been used for SO 2 

### control. However, the practical application of these controls systems to the potline reac tors and anode bake furnace is limited by the very low inlet SO 2 

### levels, in the range of 100 parts per million by volume (ppmv), and the expected range of gas conditions, incl uding temperature, oxygen content, humidity,
SO 2 

### /O 2 

### ratio, and gas impurities.

Eight different SO 2 

### control options were consider ed as having pot ential practical application as part of the BA RT analysis. Two of these technologies have been applied
to the control of SO 2 

### emissions at aluminum smelters. Six of the control options use wet scrubbing and two use dry scrubbi ng technology. The eight po tentially applicable control options are:

• 

### Limestone slurry scrubbing with forced oxidation

• 

### Limestone slurry scrubbing with natural oxidation

• 

### Conventional lime wet scrubbing

• 

### Seawater scrubbing

• 

### Dual alkali sodium/lime scrubbing (dilute mode)

• 

### Conventional sodium scrubbingIntalco BART Determination FINAL.doc 

### 5-3 • 

### Dry injection

• 

### Semi-dry scrubbing

5.1.3.1.1 Wet Scrubbing The primary development of SO 2 

### control technol ogy occurred because of the need to
control emissions from the coal-fir ed, electric utility power industry 6 

### . The large volumetric size of the potroom exha ust (approximately 1,815,000 acfm) would require a system similar to those used in the electric utility power industry.

The typical temperature range for wet scrubbers is 300 to 700°F. For utility combustion units, wet scrubbing systems have been installed on systems as large as 1,500 megawatts (MW). Sodium compounds, lime, or limestone can be used. However, the high solubility of sodium complicates disposal of waste and wastewater. The typical sorbent material is lime or limestone. Lime is generally easier to manage on-site but is significantly more costly. Wet limestone scrubbing has a high capital and operating cost due to the handling of liqui d reagent and waste, but is the preferred process for coal-fired ut ility power plants due to the low cost of limestone and high removal efficiencies. Typical removal efficiencies for wet
scrubbers are between 80 and 95%. A pproximately 85% of the flue gas desulfurization (FGD) systems installed in the United States are wet scrubber
systems 7



### .
In wet scrubbers, the waste gas enters a larg e vessel (spray tower or absorber), where it is sprayed with water slurry. The calcium in the slurry reacts with SO 2 

### to form
CaSO 3 

### . A portion of the slurry from the react ion tank is pumped into the thickener, where the solids settle before going to a filter for final dewatering to about 50% solids. Figure 5-1 is a simplified pro cess flow diagram of a conventional wet
scrubber.

6 AWMA. 2000. Air Pollution Engineering Manual , Second Edition.

7 USEPA. 2003. “Air Pollution Control Technology Fact Sheet – Flue Gas Desulfurization.” EPA-452/F-03-034. August 8.Intalco BART Determination FINAL.doc 

### 5-4 Figure 5-1. Wet scrubber process flow diagram

Inlet Gas Particulate Control Clean gas out Spray tower/absorber

Fly Ash Lime (stone) and Water Reaction Tank Calcium-based sorbent spray

Thickener

Filter

Solids

Stabilized Waste Lime

Blending Pugmill Reagent Supply Liquid Waste Stream



### In the utility industry, the CaSO 3 

### waste product is usually mixed with fly ash (approximately 1:1) and fixative lime (appr oximately 5%) and typi cally disposed of in landfills. Alternately, the forced oxidation process oxidizes the spent slurry to gypsum. Gypsum crystals dewater more e fficiently and reduce the size of waste handling equipment. Depending on qua lity and demand, the gypsum may be commercially sold, eliminating the n eed for landfilling the waste product.

“Mist eliminators” installed at the spray tower outlet or downstream ductwork remove droplets from the gas. In some pow er plant installations, the gas is reheated to avoid corrosion downstream. Many scrubbers have gas bypassing capability, which can be used for gas reheating. Ifthe wet scrubber is downstream of a highefficiency particulate removal device [fabric filter or electrostatic precipitator (ESP)], the particulate concentration may be higher leaving the scrubber than entering due to the solids in mist droplets that are carried out of the scrubber.Intalco BART Determination FINAL.doc 

### 5-5 

### Some disadvantages of using wet scrubbing techniques in many a pplications are the requirement to treat wastewater, the need to construct compone nts from expensive alloys to resist corrosion, a nd much higher energy usage. A practical issue associated with a wet scrubber system is the complexity of the system. The space required for a wet system is substantial (i.e., large foot print), the systems requi re more maintenance due to their complexity, and more pe rsonnel are required for their operation.

5.1.3.1.1.1 Limestone Slurry Forced Oxidation Limestone slurry forced oxidation (LSFO) is used extensively in the utility FGD market. The raw material is finely ground limestone. Ther e are a number of suppliers of LSFO technology. The most commonly used equipment is an open, multi-level, countercurrent spray tower sc rubber equipped with spray nozzles to inject the limestone slurry droplets into th e gas stream. Liquor is collected at the bottom of the tower and sparged with air to oxidize the calcium sulfite to calcium sulfate to enhance the settling properties of the calcium sulfate. Recirculation pumps circulate the scrubbing li quor to the spray nozzles. SO 2 

### removal
efficiencies of 90% have been achieved. Th e bleed from the scrubber is sent to a dewatering system to remove excess mois ture. For an aluminum smelter, the process will produce either solid gypsum waste or commercial-grade gypsum
suitable for reuse as a cement additive if a cement production facility is available and willing to accept the material. Only a very small purge or blowdown stream is required.

LSFO was determined to be a technically f easible retrofit control option for the potroom reactor and the anode baking exhausts even though it is not ideally suited for scrubbing SO 2 

### concentrations that are less than or equal to 105 ppm.

5.1.3.1.1.2 Limestone Slurry Natural Oxidation Limestone slurry natural oxidation (LSNO) is very similar to LSFO. The major difference is the absence of an oxidation stage. The gypsum/calcium sulfite product is essentially a waste product with limited possibilities of use for agricultural purposes.

5.1.3.1.1.3 Conventional Lime Wet Scrubbing Conventional lime wet scrubbing is also similar to LSFO ex cept that the raw material is hydrated lime or quick lime that is either slaked on- site or purchased in the slaked form. The system typically uses forced oxidation, although natural oxidation is possible. The process will produce either solid gypsum waste orIntalco BART Determination FINAL.doc 

### 5-6 

### commercial-grade gypsum suitable for reuse as a cement additive if a cement production facility is available and w illing to accept the material.

5.1.3.1.1.4 Seawater Scrubbing Seawater scrubbing is a method for controlling SO 2 

### emissions in which seawater
is used to absorb SO 2 

### in exhaust gases. Seawater is slightly alkalin e (with a pH of approximately 8). SO 2 

### has a high solubility in seawater. Absorbed SO 2 

### is subsequently oxidized to sulfates by the use of aeration and the pH is adjusted by
the addition of additional seawater.

There are three main steps in this process: absorption, oxidation, and
neutralization. Seawater is passed countercurrent through the gaseous exhaust stream, typically using a spray column in the aluminum industry. SO 2 

### preferentially dissolves in the seawater . Removal efficiencies of 85% to 95% have been measured in practice. The clean exhaust gas is de-misted prior to release to the atmosphere. The acidified seawater is then pa ssed to an oxidation basin in which air is blown through the effluent. The additional oxygen ensures
that the dissolved SO 2 

### is converted to sulfates. Finally, additional fresh seawater is added to adjust the pH back up to neut ral (or slightly alkali ne) and the seawater is discharged back into the ocean.

The effluent from this process will typical ly have a temperature increase of about 1°C and will have a change in sulfate c oncentration of approximately 2-5% above background 8,9 

### . Scrubbing of the potline emissions also adds fluoride and trace amounts of polycyclic aromatic hydrocarbons (PAHs) to the effluent seawater. No additional chemicals are required and there is normally no solid waste generated for disposal as the effluent is typically discharg ed directly to the sea. The pH of the effluent can be adjusted to within the original range in the neutralization step of the process.

The volume of seawater required vari es with exhaust flowrate and SO 2 

### loading in the gaseous exhaust stream. Based on a review of specifications for existing potline seawater scrubbing systems, the volumetric flowrate of seawater needed for proper operation of a seawater scrubber at Intalco would be approximately 2.2 million gallons of seawater per hour.

8 Information from the ALSTOM Seawater FGD – Environmental Impact website (www.environment.power.alstom.com/home/powe r/seawater_fgd/environmental_impact.htm)

9 Kwawaji, Akili D., et. al. 2005. “Seawater Scrubbing for the Removal of Sulfur Dioxide in a Steam Turbine Power Plant”. Proceeding of th e PWR2005 ASME Power Conference. April 5-7. Chicago, IL.Intalco BART Determination FINAL.doc 

### 5-7 

### A global review of feasible control tec hnologies identified s eawater scrubbing as having been installed at seven aluminum smelters, none of which are in the
United States 10 

### . Even though this technology has been identified as a control technology in operation at six primary al uminum ore reduction plants in Norway and one primary aluminum ore reduction plant in Sweden 11 

### , there are two reasons why this technology is not feasible at Intalco.

1) The Administrator of USEPA has issued environmental regulations establishing effluent limita tions guidelines (ELGs) pur suant to section 304(b) of the Clean Water Act for facilities producing primary metals from ore concentrates and recovering secondary metals from recycled wastes. The ELGs are for facilities that discharge or may discharge po llutants to waters of the United States or which introduce or may introduce pollu tants into a publicly owned treatment
works. Seawater scrubbers installed to abate SO 2 

### and other visibility impairing pollutants from the Intalco’s BART eligible potline emission units would be subject to the ELGs for “Potline SO 2 

### Emissions Wet Air Pollution Control.” 12 

### A
seawater scrubber installed downstream of the alumina dry scrubbers at Intalco
would remove both fluoride and SO 2 

### from the dry scrubber exhaust. The amount
of fluoride absorbed into the seawater would exceed the ELG, requiring treatment
of the seawater to remove fluoride before it could be discharged back into the sea. For example with three potlines operational, approximately 159 lb/day of fluoride would be absorbed by the s eawater and the applicable ELG would be 59.5 lb/day (monthly average). Removal of potline fluoride from the seawater scrubber effluent may be feasible, but would al so require precipitation of many other naturally occurring salts in the seawater (c hlorides, sulfates, ot her fluorides, etc.), resulting in the unnecessary generati on of large amounts of sludge for land disposal. Seawater scrubbing is, therefore, not a viable alternative for smelters in the United States, especially when comp ared with other scrubbing technologies that use fresh water and require treatmen t/disposal for only those salts present in the potline exhaust.

2) In addition to the regulatory restri ctions and economic viability issues discussed above, a seawater scrubber is infeasible for BART compliance due to permitting obstacles. The Washington State Environmental Policy Act (SEPA), Chapter 43.21C RCW was enacted in 1971, and it provides the framework for agencies to consider the environmental c onsequences of a proposal before taking

10 The HATCH Group. 2006. “ Analysis of Options for BART Compliance” . April 18. Page 4.

11 Ibid. Page 9.

12 40 CFR 421.23(n)Intalco BART Determination FINAL.doc 

### 5-8 

### action. It also gives agencies the ability to condition or deny proposals due to adverse impacts identified as likely to occur as a result of a proposal. The portion of Puget Sound where seawater would be w ithdrawn and discharged for an Intalco seawater scrubber has been included as pa rt of the Cherry Point Aquatic Reserve
that was established in 2000. The Aquatic Reserves Program is part of the Washington Department of Natural Resources (DNR) efforts to promote preservation, restoration, and enhancemen t of state-owned aquatic sites that
benefit the health of native aquatic habitat and species in the state. The aquatic reserves established by DNR ar e aquatic lands of special educational or scientific interest, or lands of special environmenta l importance. The construction of intake and/or discharge structures within th e Cherry Point Aquatic Reserve would require an impact analysis, assessment, and DNR authorization of any environmental impacts associated with a seawater scrubbing sy stem. Since seven years have already passed since Cherry Point was designated as an aquatic reserve and the initial SEPA evaluation has yet to be completed, the time required to complete an analysis of the environmen tal impacts associated with a seawater scrubbing system and obtain the requisite authorizations for a system that withdraws seawater from and discharges scrubber liquor into the Cherry Point Aquatic Reserve would render this tec hnology infeasible for BART compliance.

5.1.3.1.1.5 Dual Alkali Sodium/Lime Scrubbing (Dilute Mode) Dual alkali sodium/lime scrubbing (dilute mode) uses a caustic sodium solution in the scrubber tower. A por tion of the scrubbing liqui d is discharged to a neutralization stage where lime slurry is used to regenerate the caustic, which is
returned to the scrubber. The bleed fr om the scrubber is se nt to a dewatering system to produce a gypsum byproduct. The process will produce either solid gypsum waste or commercial-grade gypsum suitable for reuse as a cement additive. It should be noted, however , that dual alkali sodium/lime scrubbing (dilute mode) is not currently marketed by major FGD vendors because the system is too complicated and expensive.

5.1.3.1.1.6 Conventional Sodium Scrubbing Globally, conventional sodium scrubbing has been installed in at least 12
aluminum smelters. An alkaline solution of either soda ash or sodium hydroxide is pumped into the scrubbing tower and r ecirculated through a network of spray nozzles. Atomized droplets cont act the up-flowing gas containing SO 2 

### . Where this technology has been deployed, the li quid effluent containi ng dissolved salts, including sodium and fluorides, has been di scharged into a large receiving stream or an open body of water without treatment.Intalco BART Determination FINAL.doc 

### 5-9 

### 5.1.3.1.2 Dry Scrubbing

5.1.3.1.2.1 Dry Injection In dry injection, a reactive alkaline powder is injected into a furnace, ductwork, or a dry reactor. Typical removal efficien cies with calcium adsorbents are 50 to 60% and up to 80% with sodium base adsorbents. However, as with wet scrubbing, disposal of waste using sodium adsorbents must consider their high solubility in water compared to those from calcium adsorbents. The temperature range over which scrubbing has been used is 300 to 1,800°F; the minimum temperature is 300 to 350°F. Dry syst ems are rarely used and according to USEPA only 3% of FGD systems installed in the United States are dry systems 13



### . The dry waste material is removed using pa rticulate control devices such a fabric
filter or an ESP.

Dry scrubbing downstream of the potline reactors and anode bake furnace fabric filters is not technically feasible because of the low temperatures (less than or equal to 205°F) and low SO 2 

### concentrations (less than or equal to 105 ppm).

5.1.3.1.2.2 Semi-Dry Scrubbing (Spray Dryer) Semi-dry scrubbing is more commonly re ferred to as spray drying. Calcium hydroxide slurry (lime mixed with water) is introduced into a spray dryer tower. Sodium compounds can be used, but as with the dry scrubber, th e high solubility of the sodium-based waste products in wate r complicates disposal of the waste. The slurry is atomized and injected into a reactor with the exhaust gases, where droplets react with SO 2 

### as the liquid evaporates. This system is categorized as a semi-dry system because the end product of the SO 2 

### conversion reaction is a dry material. The dry waste product is colle cted in the bottom of the spray dryer
reactor and a fabric filter or ESP dow nstream of the spray dryer removes the
CaSO 3 

### , CaSO 4 

### , and unreacted lime. This air pollution control system uses water for evaporative cooling and for the SO 2 

### reaction. It operates in a temperature range of 300 to 350°F because the temper ature of the gases must be high enough to evaporate the water portion of the slurry. Approximately 12% of the FGD systems installed in the United States are spray dry systems 14 

### with typical SO 2 

### removal efficiencies in the range of 80 to 90%. Unlike a we t scrubbing system there is no liquid blow-down stream from the dry system and the collected solids are typically landfilled.

13 USEPA. 2003. “Air Pollution Control Technology Fact Sheet – Flue Gas Desulfurization.” EPA-452/F-03-034. August 8.

14 Ibid.Intalco BART Determination FINAL.doc 

### 5-10 

### Spray dry scrubbing downstream of the pot line reactors and anode bake furnace fabric filters is not technically feasible because of the low temperatures (less than or equal to 205°F) and low SO 2 

### concentrations (less than or equal to 105 ppm).

5.1.3.2 Pollution Prevention The guidelines for BART determinations under the Regional Haze Rule recommend consideration of pollution prevention options in addition to add-on controls. The primary opportunity for pollution prevention in the smelting process to minimize SO 2 

### emissions is through limitations on the sulfur content in the incoming coke. Coke is a major raw material used in the manufacture of green a nodes. Green anodes are subsequently baked in a furnace prior to their use in the smelting process.

Intalco’s Title V operating permit currently ha s a number of operational limits that cap
allowable emissions of SO 2 

### from the facility, including: a net potline aluminum production limit of 307,000 t on/yr; a daily potline SO 2 

### limit of 37,780 pounds per day (lb/day); limits on sulfur in coke and pitc h at 3.0% and 0.6%, respectively; and a carbon consumption limit of 0.425 pounds of carbon per pound of aluminum produced.

During the BART process, Intalco evaluated the current levels of sulfur in coke used by
other aluminum smelters to determine whet her a pollution preventi on option using lower
sulfur content coke would be a feasible BA RT option. This analysis indicated that certain smelters currently utilize coke with sulfur contents as low as 2%. Given that
sulfur contents lower than the current Inta lco specification are uti lized, Intalco undertook a low sulfur coke availability analysis to determine whether coke at levels below 3% would be available beyond 2013 when BART controls requirements are anticipated. Confidential research information belonging to the market analysts assisting with the coke availability analysis is included in Appendix B . The primary conclusions from this analysis indicate that:

• 

### Coke is a byproduct of the oil refining pro cess. The sulfur content of the world’s crude oil supply has been and will continue increasing in sulfur content. Those refiners with coking capacity are mi nimizing their raw material costs by maximizing use of high sulfur crude oils and oil sands to the optimal extent for their overall refinery design. The result will be a continuing increase in the sulfur
content of available coke.

• 

### Coke is a relatively small, low revenue component of the refinery’s product profile. As such, the aluminum industry has little influence in controlling the quantity, quality, and price of th e coke produced by refineries.Intalco BART Determination FINAL.doc 

### 5-11 • 

### Anode grade (or anode quality) coke is a small subset of the total coke produced
world-wide. Growth in the aluminum industry has increased the demand for the limited quantities of anode grade coke and has driven prices for coke to unprecedented levels. Refining higher sulf ur crude oils and oil sands further shrinks this small subset of anode grade coke.

• 

### Prices for coke nearly doubled from 1994 to 2006.

• 

### The increased global growth in aluminum production will continue to outpace the production of coke.

• 

### Primary aluminum production is expected to grow at the rate of 3 to 4% annually, resulting in a commensurate growth in demand for anode grade coke.

• 

### Coke providers are blending imported, high cost, lower sulfur coke with domestically sourced coke in attempts to meet the current specification requirements for coke.

• 

### Removal or reduction of the sulfur content of the coke once it has been received is
not feasible.

• 

### Aluminum smelters are experimenting w ith alternative coke s and technologies that are outside of the traditional specifi cations to ensure continued aluminum production in the face of the changing char acteristics of this key raw material.

• 

### The deterioration in coke quality and the tightness of supply is expected to
continue for the foreseeable future.

• 

### The increased demand for coke will for ce the aluminum industry to accept lower quality coke with hi gher sulfur contents.

Based on the market and availability anal ysis of the future coke supply, Intalco
determined that it is infeasible to consider coke at sulfur contents below 3% as a BART pollution prevention option because a supply of coke with sulfur contents below 3% cannot be ensured beyond 2013 when BART cont rol requirements are anticipated. These same market pressures are expected to force facilities currently us ing coke with sulfur contents below 3% to begin using higher sulf ur content coke in the future. Although
coke at sulfur contents below 3% is considered infeasible due to availability concerns, a pollution prevention option that maintains Intalco’s current sulfur in coke limit of 3% is considered technically viable or feasible, assuming that sufficient imported lower sulfur
coke remains available to allow blen ding to 3% sulfur content beyond 2013.Intalco BART Determination FINAL.doc 

### 5-12 

### 5.1.3.3 Feasible Control Options from RBLC Database

A review of USEPA’s RACT/BACT/LAER Clearinghouse (RBLC) da tabase was also completed to determine which control technol ogies or techniques ha ve been utilized by primary aluminum ore reduction plants. The results from the RBLC database search are
summarized in Table 5-1.

The data in the RBLC database support the approach of limiting ra w material sulfur content as a control option for the potlines and the anode bake furnace. Many facilities
have limited sulfur content in coke to limit SO 2 

### emissions. Two facilities have limits of
3% sulfur content in coke and one has a 2.95% sulfur content limit. One facility is shown
in the RBLC to have a wet scrubber to control SO 2 

### emissions; however, an investigation revealed that the wet scrubber was not requi red as part of a be st available control technology (BACT) determination and that th e facility currently does not operate a wet
scrubber to control SO 2 

### emissions. That facility’s current Title V permit for “Potline 5” simply limits coke sulfur content to 3% and coal tar pitch sulfur to 0.8%.

Dry alumina scrubbers (with fabric filters) ar e the controls that have been considered
BACT for PM.

5.1.4 Potentially Applicable BART Control Options for PM Potentially applicable PM em ission controls are discusse d in the following sections.

5.1.4.1 Fabric Filters Fabric filters generally prov ide high collection efficiencies for both coarse and fine (submicron) particles. They are relatively insensitive to fluctuations in gas stream conditions. Efficiency is relatively unaffected by large changes in inlet dust loadings. Filter outlet air is very clean 15 

### . Collected material is dry, whic h usually simplifies processing or disposal. Fabric filters ar e currently applied for controlling PM em issions from the potrooms and the anode bake furnace at Intalco.

5.1.4.2 Electrostatic Precipitators ESPs are capable of very high removal e fficiencies for large and small particles 16 

### . They offer control efficiencies that are comparable to fabric filters. B ecause of their modular design, ESPs, like fabric filters, can be applied to a wide range of system sizes. The operating parameters that influence ESP performance include fly ash mass loading, particle size distribution, fly as h electrical resistivity, and preci pitator voltage and current.

15 USEPA. 2003. “Air Pollution Control Technology Fact Sheet – Fabric Filter.” EPA-452/F-03-025. August 7.

16 USEPA. 2003. “Air Pollution Control Technology Fact Sheet – Dry Electrostatic Pr ecipitator.” EPA-452/F-03- 028. August 7.Intalco BART Determination FINAL.doc 

### 5-13 

### Dusts with high resistivities are not well-su ited for collection in dry ESPs because the particles are not easily charged. This also affects the ash layers on the collecting
electrodes. An ESP is techni cally feasible for control of PM from the potrooms and the
anode bake furnace at Intalco.

5.1.4.3 Cyclones, Inertial Separators, and Wet Scrubbers Cyclones and inertial separators are used for collection of medium-sized and coarse particles. Wet scrubbers generally remove la rge particles but can remove small particles with the use of high pressure drops. However, none of these devices are as effective at removing small and submicron particles as fabric filters and ESPs 17



### .

5.1.5 Potentially Applicable BA RT Control Options for NO x 

### Potentially applicable NO x 

### emission controls in clude combustion controls and post-combustion
controls.

5.1.5.1 Combustion Controls

The concentration of NO x 

### in the potroom reactor exhaust is extremely low (less than 1 ppm) because there is no external fuel or combustion zone and there are no large sources of nitrogen in the raw materials. Traditional methods of preventing NO x 

### formation using staged combustion or low NO x 

### burners are not applicable to the potlines at Intalco.

NO x 

### emissions from anode baking depend on operating practices and burner controls. The traditional methods of preventing NO x 

### formation using staged combustion or low
NO x 

### burners are not appli cable because of the unique conf iguration of an anode baking ring furnace, with fuel injected at several points in narrow flues. However, advanced firing systems that measure and regulate fuel flow precisely using a computerized control system may reduce NO x 

### emissions by reducing total fuel usage. Prevention of NO x 

### formation using advanced firing control is tech nically feasible for the anode bake furnace
at Intalco.

5.1.5.2 Post-Combustion Controls Selective non-catalytic reduction (SNCR), se lective catalytic reduction (SCR), and low temperature oxidation (LoTOx) controls are discussed in this section.

5.1.5.2.1 Selective Non-Catalytic Reduction SNCR is an add-on technique that involves injecting ammonia or urea into a specific temperature zone in a furnace or boiler. The ammonia or urea reacts with NO x 

### in the gas to produce nitrogen and water. SNCR typically provides a NO x 

### reduction of 30 to 50%.Intalco BART Determination FINAL.doc 

### 5-14 

### The effectiveness of SNCR depends on the te mperature where reagents are injected, mixing of the reagent in the gas, residence time of the reagent within the required temperature window, and the ratio of reagent to NO x 

### . The required temperature window is 1,600 to 2,100°F. Typical uncontrolled NO x 

### levels where this technology has been applied vary from 200 to 400 ppm. SNCR is less effective at lower levels of uncontrolled
NO x 18



### .
The temperature (approximately 200°F) and NO x 

### concentration (less than 1 ppm) of the potroom emission exhaust are outside the le vels where SNCR could be used. Thus, SNCR is not technically feasible for the potlines at Intalco.

The temperature of the anode baking emi ssion exhaust (300 to 450°F) is below the temperature where SNCR could be used. Down stream of the reactor where tar vapors are removed, the temperature is approximately 200° F, which is also below the appropriate range. In addition, the NO x 

### concentration (less than 20 ppm) is below the level where SNCR could be used. Thus, SN CR is not technically feasible for the anode bake furnace
at Intalco.

5.1.5.2.2 Selective Catalytic Reduction SCR is an add-on technique similar to SNCR that involves injecting ammonia into flue gas in the presence of a meta l-based catalyst to convert NO x 

### emissions to elemental nitrogen and water. The catalyst allows SCR systems to operate at much lower temperatures than SNCR; typical temperatur es for SCR are 500 to 800°F, compared with 1,600 to 2,100°F for SNCR. The optimum temperature range is 700 to 750°F 19 

### . SCR is capable of NO x 

### reduction efficiencies in the range of 70 to 90% and can be used with
NO x 

### concentrations as low as 20 ppm. However, higher NO x 

### levels result in increased performance 20



### .
The temperature of the potroom emissi on exhaust (approximately 200°F) and NO x 

### concentration (less than 1 ppm ) of the potroom emission exhaust are outside the levels where SCR could be used. Thus, SCR is no t technically feasible for the potlines at
Intalco.

The temperature of the anode baking emi ssion exhaust (300 to 450°F) is below the temperature where SCR could be used. Downst ream of the reactor where tar vapors are

17 AWMA. 2000. Air Pollution Engineering Manual , Second Edition.

18 USEPA. 2003. “Air Pollution Control Technology F act Sheet – Selective Non-Ca talytic Reduction.” EPA452/F-03-031. August 8.

19 USEPA. 2002. EPA Air Pollution Control Cost Manual , Sixth Edition. EPA/452/B-02-001. January.

20 USEPA. 2003. “Air Pollution Control Technology F act Sheet – Selective Catalytic Reduction.” EPA-452/F-03- 032. August 8.Intalco BART Determination FINAL.doc 

### 5-15 

### removed, the temperature is approximately 200° F, which is also below the appropriate range. In addition, the NO x 

### concentration (less than 20 ppm) is below the level where SCR could be used. Thus, SCR is not technica lly feasible for the anode bake furnace at
Intalco.

5.1.5.2.3 Low-temperature Oxidation Technology (LoTOxTM) The LoTOxTM system is the patented t echnology of BOC Gases. In this NO x 

### removal system, ozone is injected into the exhaust gas stream in order to oxidize insoluble NO x 

### to soluble nitrogen compounds, including N 2 

### O 5 

### . N 2 

### O 5 

### is highly soluble and reacts with moisture in the gas stream to form nitric ac id. A scrubber is required downstream of the LoTOxTM system to remove the nitric acid formed by the reaction of N 2 

### O 5 

### and moisture in the gas stream. The ozone is typically generated on site and on demand. Since LoTOxTM is a low temperature system it does no t require heat input and the low operating temperature (150 to 250°F) allows for stable an d consistent control ev en with variations in flow, load, and NO x 

### concentrations 21



### .
Use of the LoTOxTM system has not been demons trated at an aluminum plant. Research indicates that application of the LoTOxTM t echnology has been limite d to a sulfuric acid regeneration plant, a lead smelting reverbatory furnace, a stainless steel plant, a coal-fired electric generation unit, a nd two fluidized-bed catalytic cracking units (FCCU) at
refineries 22,23 

### . Reported NO x 

### removal efficiencies for the LoTOxTM system are on the
order of 90% to 95%.

The temperature of the anode baking emissi on exhaust (approximately 200°F) is within the temperature range where LoTOxTM could be used. Although th is technology has not
been demonstrated on an anode bake furn ace, low-temperature oxidation technology may be technically feasible for reducing anode bake furnace NO x 

### emissions.

5.1.6 Summary of Technically Feas ible BART Control Options

5.1.6.1 Feasible BART Control Options for SO 2 

### Two technically feasible options were identified for controlling SO 2 

### emissions from the potlines and anode bake furnace:

• 

### Adding a wet scrubber to th e potline and/or anode bake furnace exhausts, and

21 BOC Process Gas Solutions. 2001. Low Temperature Oxidation System Demonstration at RSR Quemetco, Inc., City of Industry, California. June 28. (www.arb.ca.gov/ research/icat/pro jects/boc.pdf)

22 USEPA. 2005. “Using Non-Thermal Plasma to Control Air Pollutants”. EPA-456/R-05-001. February. www.epa.gov/ttn/catc/dir1/fnonthrm.pdf

, 23 USEPA RACT/BACT/LAER Clearinghouse (RBLC) database.Intalco BART Determination FINAL.doc 

### 5-16 • 

### A pollution prevention option limiting the su lfur content in the coke used to produce anodes to 3.0%.

These two options were evaluated further as part of the BART determination analysis.

5.1.6.2 Feasible BART Control Options for PM Cyclones, inertial separators, wet scrubbers, ESPs, and fabric filters are all technically feasible for controlling potroom PM emissions. However, ESPs and fabric filters are superior devices for controlling fine PM.

Fabric filtration with dry alumina scrubbi ng has been widely used in the primary aluminum industry. Most smelters constructe d within the past 20 years have used dry alumina scrubbing with fabric filters to contro l emissions from potlines. A few plants use control systems consisting of ESPs to coll ect PM followed by spray towers to scrub gaseous fluoride. Wet systems have ma ny disadvantages, such as corrosion by hydrofluoric acid, scaling, and the requirement to treat wastewater. ESPs and wet systems are no longer installed on new smelters 24



### .
Dry scrubbers are widely used on anode bake furnaces because they provide effective removal of hydrocarbons, fluorides, and PM. Wet systems have the same disadvantages for anode bake furnaces as for potlines: corrosion by hydrofluoric acid, scaling, and the requirement to treat wastewater. Dry scrubbers with fabric filters are a superior choice
for anode bake furnaces.

Given that fabric filters are already used for PM control a nd that these high-efficiency devices are superior or equal to other feasible c ontrol options, no further analysis of PM controls was performed.

5.1.6.3 Feasible BART Control Options for NO x 

### Since there is no external fuel or combus tion zone in the smelting cells, there are no technically feasible pre-combustion NO x 

### controls. Likewise, there are no technically feasible add-on controls because of the temperature of the potroom exhaust (approximately 200°F) and low NO x 

### concentration (less than 1 ppm).

Advanced firing systems may prevent NO x 

### formation by reducing natural gas usage and are technically feasible for the anode bake furnace. Add-on SCR and SNCR controls are
not feasible at the furnace exhaust because of the temperature (less than 450°F) and presence of tar vapor. SCR and SNCR ar e not feasible downstream of the reactor because of the temperature (a pproximately 200°F) and low NO x 

### concentration (less than

24 Air and Waste Management Association (AWMA). 2000. Air Pollution Engineering Manual , Second Edition.Intalco BART Determination FINAL.doc 

### 5-17 

### 20 ppm). The use of low temperature oxidati on (LoTOxTM) may be a viable option for reducing NO x 

### emissions if a wet scrubber were installed on the bake furnace for SO 2 

### control.

The option for reducing NO x 

### formation through advanced firing systems for the anode bake furnace was evaluated further as part of the BART determination analysis. Further consideration was also give n to the potential use of low temperature oxidation (LoTOxTM).

5.2 C ONTROL 

### E FFECTIVENESS OF 

### F EASIBLE 

### O PTIONS 

### Step 3 of the BART analysis is to evaluate the control effectiveness of the technically feasible control technologies.

5.2.1 SO 2 

### Wet Scrubbing A wet scrubber was identified as a technically feasible add-on pollution control option to
reduce SO 2 

### from the potline reactors. Typical removal efficiencies are 80 to 95%. Capital cost estimates and control efficien cies for wet scrubbers at Intalco were developed by scaling costs fr om two vendor quotes obtained for the in stallation of LSFO scrubbing technology at Alcoa’s fa cility in Alcoa, Tennessee. Each of the vendors that provided proposals for the Tennessee f acility indicated that a 95% SO 2 

### removal was technically feasible. Accordingly, an SO 2 

### removal efficiency of 95% was used in the Intalco BART analysis for the wet scrubber control option.

Mist droplets will be a compone nt of the gas stream emitted from the scrubber. Solids in the droplets will become airborne PM when th e water in the droplets evaporates. The PM
concentration in the outlet of the wet scrubber was predicted to be 20 mg/Nm 3 

### by one of the vendors. This compares to a concentration of 10 mg/Nm 3 

### currently emitted from the existing potline control system. Conseque ntly, the wet scrubber option would cause a collateral increase in PM from the potlines.

A wet scrubber was also identified as a te chnically feasible a dd-on pollution control option for the anode bake furnace since it has an SO 2 

### concentration and a temperature similar to the potline reactor exhaust. However, the anode bake furnace is a smaller source than the potlines because of the lower exhaust gas flow rate (1,950,000 acfm versus 202,500 acfm). A separate vendor cost proposal was not obta ined for the anode bake furnace, but an SO 2 

### removal efficiency of 95% is assumed to be feasible. Wet
scrubber costs for the anode bake furnace we re also scaled from the LSFO potline wet scrubber vendor quotes.Intalco BART Determination FINAL.doc 

### 5-18 

### Table 5-2 summarizes the SO 2 

### , NO x 

### , and PM emission levels under the control scenarios considered for BART. The emissions represent the combined total emissions from the primary and secondary potline control syst ems and the anode bake furnace for each scenario. Control scenario #1 is the addition of a wet scrubber to the potline reactors.
Control scenario #2 is the addition of a we t scrubber to the anode bake furnace. The current potential emissions with 3.0% sulf ur coke are also listed. The emissions
reductions achievable for each of the scenar ios were compared to current potential
emissions.

5.2.2 SO 2 

### Pollution Prevention The pollution prevention option re presents a 3.0% sulf ur limit in the coke used to produce anodes. This option reflects the current sulfur limit in Intalco’s Title V operating permit.

5.2.3 Anode Bake Furnace Advanced Firing System

NO x 

### emissions from the anode bake furnace could be reduced by incorporating an advanced firing system. Total gas usage is projected to be reduced by 20%, which would result in a corresponding 20% reduction in NO x 

### emissions, or approximately 27 tons/year.

5.2.4 Anode Bake Furnace LoTOx TM 

### System

NO x 

### emissions from the anode bake furnace coul d potentially be reduced by using the LoTOx TM 

### system for post-combustion contro l. This technology has a cont rol efficiency of 90% for NO x 

### emissions when combined with wet scrubbi ng, resulting in a potential reduction in NO x 

### emissions of approximately 122 tons/year.

5.3 E VALUATION OF 

### C OSTS AND 

### O THER 

### I MPACTS 

### Step 4 of the BART analysis involves evaluati on of cost and other impacts, including energy impacts, greenhouse gas generation, non-air quality environmental impacts, and remaining useful life. Costs of control, energy impacts, greenhouse gas generation impacts, non-air quality environmental impacts, and remaining usef ul life are evaluated in this section.

5.3.1 Cost Impacts for Feasible Controls

5.3.1.1 Wet Scrubbers The exhaust gases from each potline are routed to dry alumina reactors. Potline gases currently exhaust to atmosphere from stacks above the fabric filters in each of the six baghouse scrubbing centers, which are located in courtyards between the potrooms.

Wet scrubber costs for Intalco were estimated based on cost quotes received by Alcoa from two flue gas desulphurization equipmen t vendors. The cost quotes were originally provided as part of the BART analysis for Alcoa’s Tennessee Operations in Alcoa, TN.Intalco BART Determination FINAL.doc 

### 5-19 

### Both vendors provided cost proposals for wet scrubbing systems based on limestone forced oxidation (LSFO) SO 2 

### scrubbers. Lime- or sodium-b ased scrubbers could also be used for potlines, but lime and sodium are less desirable reagents considering that these reagents are much more expensive. An advantage of the limestone forced oxidation process is that the spent slurry is oxidized to gypsum, which dewaters more efficiently, resulting in less waste materials requiring disposal. Thus, an LFSO scrubber was determined to be the most appropriate cont rol device for the cost analysis. The vendor proposals are provided in Appendix B. These proposals contain confidential business information and are, therefore, labeled as confidential.

Neither of the two vendors provided a compre hensive installed cost estimate. Both preliminary designs were based on a central scrubbing center as the least cost approach, where exhaust from all dry scrubbing systems would be ducted to a centralized scrubbing system. Both design estimates were ba sed on systems that would provide 100% availability of emissions control on each day of the year, given that potlines cannot be easily shutdown and restarted for control system outages.

One vendor provided an estimate of the scrubbe r equipment only. The other provided an “indicative price,” with an inst alled cost assumed equal to th e equipment cost. Important retrofit considerations for installing a potlin e wet scrubbing system include: (1) that gases must be collected from multiple indivi dual baghouse stacks, (2) the system must simultaneously maintain balanced flow from multiple potline control devices, and (3) the system installation would require transpor t of new components through narrow passages in the existing potline. Coordination of the equipment delivery and the daily work schedule of the potline operation would also a ffect the control system installation. One of the vendors recognized the co mplexity of this project, poi nting out in their proposal that an extensive engineering effort was needed because of space limitations, access limitations, uncertainty as to laydown areas, and uncertainty of ductwork and supports. These retrofit issues would apply equally to both the Alcoa, TN facility and Intalco.

The vendor cost proposals for the Tennessee fa cility were based on a total scrubber exit gas volume of approximately 1,580,000 acfm at 101 o 

### F compared to a design exit gas volume of approximately 1,950,000 acfm at 98 o 

### F for Intalco. Vendor equipment cost proposals for the Alcoa, TN facility ther efore had to be adju sted to account for differences in exhaust gas volume and other design parameters.

Hatch, an engineering firm contracted by Alco a, prepared a pre-feasibility report for Intalco in which equipment costs provided by one of the vendors for the Alcoa, TN facility were scaled or adjusted to estim ate LSFO equipment costs for Intalco. The procedure used by Hatch adjusted equipment cost estimates using appropriate exponentialIntalco BART Determination FINAL.doc 

### 5-20 

### factors for equipment type (reagent feed, SO 2 

### removal, gas handling, etc.), along withdifferences in system exhaust gas volume, limestone consumption, and gypsum byproduct generation. ENVIRON used the cost adjustment approach developed by Hatch to prepare an average equipment cost ba sed on both vendor quotations. The equipment cost scaling procedures are out lined in the Hatch report in Appendix C and ENVIRON’s parallel calculations based on the average of the two vendor quotes are provided in Appendix D

.
The average scrubber equipment cost was used with factors from the EPA Air Pollution
Cost Control Manual 25 

### to determine installation costs and total capital costs. Operating costs were calculated based on utility and raw material requirements provided by Hatch, along with unit cost information provided by In talco and other cost assumptions from the
EPA Air Pollution Cost Control Manual . Complete cost calcul ations and assumptions are provided in Appendix D

.
Separate vendor cost quotes were not obtained for installing a wet SO 2 

### scrubbing system on the anode bake furnace. Instead, the potline SO 2 

### scrubber equipment costs were
scaled to estimate Intalco anode bake cont rol equipment costs usi ng the same approach discussed above for the potlines. The anode bake wet scrubber de sign was based on a scrubber exhaust gas volume of 202,500 acfm at 98 o 

### F. The vendor equipment costs were adjusted using exponential factors that acc ount for differences in exhaust gas volume, limestone consumption, and gypsum by-product generation.

Table 5-3 summarizes the cost of installi ng and operating an LSFO wet scrubber on the Intalco potlines and anode bake furnace to remove 95% of the SO 2 

### . The capital and total annualized costs for a potline wet scrubber are high at approximately $234.5 million and $46.8 million per year, respectively. The wet scr ubber cost effectiveness is also high at $7,500 per ton of SO 2 

### removed.

The estimated installed capital cost to a dd a wet scrubber to remove 95% of the SO 2 

### from
the anode bake furnace exhaus t would be approximately $29.5 million with an annualized cost of $6.3 million per year. The wet scrubber cost effectiveness is also high at $36,400 per ton of SO 2 

### removed.

5.3.1.2 Coke Sulfur Limit Intalco is currently able to obt ain coke with 3.0% sulfur without incurring significant additional cost. However, as low sulfur coke becomes more difficult to pr ocure, the cost will increase. Additional information regarding low sulf ur coke availability is included in Appendix B

.

25 USEPA. 2000. EPA Air Pollution Cost Control Manual , Sixth Edition. EPA-452/B-02-001. January 2002 (and updates).Intalco BART Determination FINAL.doc 

### 5-21 

### 5.3.1.3 Anode Bake Furnace LoTOx TM 

### System

Cost data for the LoTOx TM 

### system is not readily available. However, as demonstrated above for
the control of SO 2 

### emissions from the anode bake furnace, the cost of the downstream scrubber required for the use of the LoTOx TM 

### system would make this option cost prohibitive. NO x 

### emissions are lower than SO 2 

### emissions for the anode bake furnace, so the cost per ton values for
NO x 

### would be even higher than for SO 2


### .

5.3.2 Energy Impacts

A wet scrubber removes SO 2 

### by forcing the exhaust gas through a spray tower or absorber where it contacts water droplets that contain the unre acted lime or limestone. Energy is required to overcome the resistance of the scrubber compone nts as well as falling water droplets. A substantial amount of energy would be associated with fans to move the potline and anode bake furnace exhaust streams through scrubbers. Othe r energy is required for the slurry pumps, instrumentation, and miscellaneous items (e .g., lighting). The total energy required 26 

### would be approximately 7,400 kilowatt-hours (kWh)/hr for the potline scrubber and 750 kWh/hr for the anode bake furnace scrubber. As listed in Table 5-3, this is equivalent to 64,824,000 kWh of electricity per year for the potline scrubber. A wet scrubber on the anode bake furnace would add 6,570,000 kWh per year.

5.3.3 Greenhouse Gas Generation Greenhouse gases (GHGs) are gaseous compounds that are known to provide a warming effect to the atmosphere. The predominant GHG is carbon dioxide (CO 2 

### ). Other GHGs include nitrous oxide and methane. The proposed SO 2 

### control devices will increas e overall emissions of GHGs via three mechanisms: (1) as a byproduct of the reaction chemistry in the scrubbers, (2) as indirect emissions from the generation of electri city required to power the scrubbing systems, and (3) as direct emissions from vehicle travel for the additional personnel that will be required at the facility to maintain and operate the scrubbing systems. The details of the GHG emission calculations for each of these mechanisms are presented in the Appendix E

.

The total GHGs (in carbon dioxide equivalents) generated by th e implementation of the proposed scrubbing system for the potline fumes was estimated to be 96,441 pounds per day, or 17,597 tons per year. The total GHGs (in carbon dioxide equivalents) generated by the implementation of the proposed scrubbing system for the anode baking furnace was estimated to be 7,298 pounds per day, or 1,330 tons per year.

5.3.4 Non-Air Quality Environmental Impacts Both of the wet scrubber proposals were based on the LSFO process. This process oxidizes the spent slurry to gypsum, which may be landfilled or commercially sold. There is no way to knowIntalco BART Determination FINAL.doc 

### 5-22 

### at this time whether the gypsum would have commercial value or whether there would be any demand for it. Therefore, it must be assumed that 27,130 tons of waste from a potline wet
scrubber and 639.5 tons of waste from an anode bake furnace wet scrubbe r would be landfilled each year.

It is estimated that 182.5 million gallons of water will be required annually to operate the potline wet scrubber at a cost of approximately $97,000. This will significantly impact the community infrastructure in that this will increase Intalco’s daily water demand by approximately 9% 27



### .
It is also estimated that a total of approxima tely 71.4 million kWh would be needed to operate the potline and anode bake furnace scrubbers annua lly. This would impact power demand in the community and would also have an environmenta l impact due to power production equivalent to adding approximately 6,700 new households in the community 28



### .

5.3.5 Remaining Useful Life The Intalco smelter has been in operation si nce 1966 and remains a cr itical component of Alcoa’s aluminum production in th e United States. The facility intends to be in operation throughout the period of the Regional Haze Program.

5.4 E VALUATE 

### V ISIBILITY 

### I MPACTS 

### Step 5 of the BART analysis involve s evaluation of visibility impact s. More specifically, this is an evaluation of the potential improvement in vi sibility resulting from application of feasible pollution prevention/add-on control options. Refined CALPUFF modeling was performed for
two control scenario s: one with wet SO 2 

### scrubbing applied to the potline and one with wet SO 2 

### scrubbing applied to the anode bake furnace. This modeling was accomplished according to State of Washington’s BART modeling protocol 29 

### . In general, this modeling was the same as the baseline modeling except stack data and emission data associated with the application of the
feasible add-on controls were used as model inputs. Table 5-4 presents the post-control modeling source input data that we re used in the CALPUFF model to forecast visibility impacts for the two control options.

Table 5-5 presents the results of modeling with the two scrubber SO 2 

### control scenarios along with baseline impacts. As shown in Table 5-5, the addition of a potline wet scrubber reduced

26 Hatch. 2007. SO 2 Scrubbing for the INTALCO Primary Alum inum Smelter: Pre-Feasibility Report. July 26.

27 Based on average facility incoming water flow rates for 1998 through 2000, the th ree most recent years the facility was at full production.

28 Calculated based on 2001 average energy usage per hou sehold for the United States as reported by the Department of Energy ( http://www.eia.doe.gov/emeu/reps/enduse/er01_us_tab1.html ).

29 Modeling Protocol for Washington, Oregon, and Idaho: Protocol for the Application of the CALPUFF Modeling System Pursuant to the Best Available Retrofit Technology (BART) Regulation. October 11, 2006. www.deq.state.or.us/aq/h aze/docs/bartprotocol.pdfIntalco BART Determination FINAL.doc 

### 5-23 

### modeled visibility impacts in all five Class I areas to between approximately 0.1 and 0.35 dv for the three years modeled. For example, the baselin e modeling results indicate that the highest 98 th 

### percentile visibility imp act from Intalco’s BART-eligible sour ces at Olympic National Park with
3% sulfur in the coke was 1.527 dv. The post-control modeling resu lts indicate that the highest
98 th 

### percentile visibility impact from Intalco’s BART-eligible sources at Olympic National Park with wet scrubbers installed on the potlines was 0.355 dv in 2003. This represents a 1.17 dv reduction in total facility visibility impacts at Olympic National Park with the addition of wet scrubbers on the potlines.

The modeled visibility improvements shown in Table 5-5 from adding a wet scrubber at the anode bake furnace are minimal, with impr ovements ranging from approximately 0.004 to 0.024 dv compared to the baseline conditions. For exam ple, the post-control modeling results for the anode bake furnace indicate a highest 98 th 

### percentile visibility impact of 1.503 dv compared to the baseline value of 1.527 dv in 2003. This represen ts less than a 2% reduction in total facility visibility impacts at Olympic Na tional Park with the addition of wet scrubbers on the anode bake
furnace.

For NO x 

### , the use of an advanced firing system or LoTOx TM 

### technology for the anode bake furnace would also result in minimal improvements in visibility. The baseline visibility modeling indicated th at the highest 98 th 

### percentile visibility impact due to anode bake furnace
NO x 

### emissions was approximately 0.03 dv (55% of 0.053 dv). Therefore, a 20% reduction in
NO x 

### emissions from the anode bake furnace with th e use of an advanced firing system would reduce Intalco’s total visibility impacts by a pproximately 0.006 dv and a 90% reduction with the
use of LoTOx TM 

### would reduce the impacts by approximately 0.027 dv. Based on the minimal change in visibility forecast resulting from the in stallation of an advanced firing system or use of
LoTOx TM 

### , it was determined that neither of these t echnologies represents reasonably effective BART control technologies for the anode bake furnace.Intalco BART Determination FINAL.doc 

### 6-1 

## 6.0 DETERMINATION OF BART

6.1 A LUMINUM 

### P OTLINES 

### For potline SO 2 

### emissions, BART was determined to be the current level of control, which is a pollution prevention limit of 3% sulfur in the coke used to manufacture anodes. A pollution prevention limit based on coke sulfur contents below 3% was determined by Intalco to be infeasible as BART for 2013 and beyond based on a ma rket and availability analysis for future coke supply. Use of wet scr ubbing technology to reduce potline SO 2 

### emissions was rejected as
BART due to excessive costs: total co st effectiveness of $7,500 per ton of SO 2 

### removed and capital and total annualized costs of $234.5 m illion and $46.8 million per year, respectively. A potline wet scrubber would also have substantial secondary impacts, including increased energy usage of 64,824,000 kWh of electricity per year , added water consumption of 183 million gallons per year, and solid waste generation of 27,000 tons per year.

For PM emissions, BART was determined to be the current level of control, which is the use of baghouses to control PM emissions from the alum ina dry scrubbers and wet roof scrubbers to control secondary PM emissions from the potroom roofs.

There are no feasible technologies for control of NO x 

### from the potlines; thus, BART for NO x 

### was determined to be no controls.

6.2 A NODE 

### B AKE 

### F URNACE 

### A pollution prevention limit of 3% sulfur in the c oke was also determined to be BART for anode
bake furnace SO 2 

### emissions. The cost of wet scrubbing to reduce SO 2 

### emissions would be excessive at $36,400 per ton of SO 2 

### removed while providing minimal visibility improvement.

The existing level of control (based on baghouses on the alumina dry scrubbers) was determined
to be BART for PM emissions.

BART for anode bake furnace NO x 

### emissions was determined to be no controls. The use of an advanced firing system for reduced energy use was rejected as BART because the technology would result in negligible visibility imp rovement. Similarly, the use of LoTOx TM 

### was rejected as BART because the cost of the technology would be excessive and result in negligible visibility improvement.Intalco BART Determination FINAL.doc 

### 6-2 

### 6.3 A LUMINUM 

### H OLDING 

### F URNACES 

### BART for the aluminum holding furnaces was dete rmined to be no controls. The use of additional controls was rejected as BART because any visibility improvement would be negligible.

6.4 M ATERIAL 

### H ANDLING AND 

### T RANSFER 

### O PERATIONS 

### PM emissions from the BART-eligible materi al handling and transfer operations are all controlled using fabric filter tec hnology. This existing level of em issions control was determined
to be BART for these material ha ndling and transfer operations.

# TABLESProcess
Number Emission Unit
ID Emission Unit Description Visibility Impairing
Pollutants Existing
Pollution Controls Modeling Source Type

5 181-186 Potline primary emission control system stacks PM, SO
x Reactor/
Fabric Filter Point

5 22-180 Potline secondary emission control system stacks PM, SO
x Roof Water
Scrubbers Line

3 187 Anode bake furnace PM, SO
x , NO
x Reactor/
Fabric Filter Point

6 4, 5, 7, 8, 10, 11, 13, 14, 16-19 Aluminum holding furnaces PM Fabric Filter Point

2 188 Paste plant baghouse stack PM Fabric Filter Point 2 189 Phase A ball mill baghouse stack PM Fabric Filter Point 2 191 Phase B ball mill baghouse stack PM Fabric Filter Point

7 195 Primary WTP kiln wet scrubber PM Wet Scrubber Point

4 198 Rod shop (west) baghouse stack PM Fabric Filter Point 4 199 Rod shop (east) baghouse stack PM Fabric Filter Point 7 208 Ladle cleaning baghouse stack PM Fabric Filter Point 7 209 Autogenous mill baghouse stack PM Fabric Filter Point 7 210 TAC station baghouse stack PM Fabric Filter Point
6 217 Remelt furnace stack PM Point 2 232 Butts baghouse stack PM Fabric Filter Point 4 260 Aluminum spray cyclone stack PM Point 4 312 Rod shop induction furnace (east) stack PM Point 4 313 Rod shop induction furnace (west) stack PM Point 2 316 Pitch fume treatment system PM Point 3 251 Anode bake building monitor roof PM Volume
3 252 Anode block hole blower PM Volume 4 257A Rod shop crust recovery discharge to trucks from bins #1 and #2 PM Volume 4 257B Rod shop crust recovery discharge to trucks from bins #1 and #2 PM Volume 4 259A Rod shop carbon recovery discharge to trucks from bins #1 and #2 PM Volume 4 259B Rod shop carbon recovery discharge to trucks from bins #1 and #2 PM Volume 7 280 Annex cathode assembly area roof vents PM Volume 7 282 Annex ramming paste area roof vents PM Volume
1 239 Paved road vehicle dust emissions PM Area 1 241 Facility-wide natural gas combustion PM, SO
x , NO
x Area 7 273 Alumina ore handling fugitive dust PM Area

1 233 General welding PM Volume (combined)

1 240 Fugitive dust from loading and dumping waste PM Volume (combined)

1 242 Plant-wide propane combustion emissions PM, SO
x , NO
x Volume (combined)

2 190 Phase "A" mixer fugitives PM Volume (combined)

2 192 Phase "B" mixer fugitives PM Volume (combined)

2 193 KVS ball mill baghouse stack PM Fabric Filter Volume (combined)

2 194 Pet coke baghouse stack PM Fabric Filter Volume (combined)

2 243 Paste plant roof vents PM, SO
x , NO
x Volume (combined)

2 244 Phase "A" paste cooling conveyor fugitives PM Volume (combined)

2 245 Phase "B" paste cooling conveyor fugitives PM Volume (combined)

2 248 Scrap paste storage bins PM Volume (combined)

2 249 Paste plant vacuum system baghouse stack PM Fabric Filter Volume (combined)

3 250 Packing coke silo vent PM Volume (combined)

4 253 Rod shop roof vents (north) PM Volume (combined)

4 254 Rod shop roof vents (south) PM Volume (combined)

4 255 Hot anode butts transport PM Volume (combined)

4 256A,B Rod shop crust recovery discharge to storage bins #1 and #2 PM Volume (combined)

4 258A,B Rod shop carbon recovery discharge to storage bins #1 and #2 PM Volume (combined)

4 263 Cooling of cast iron dross sows outside rod shop PM Volume (combined) Table 3-1 Primary Aluminum Reduction Emission Units
Alcoa Intalco Works Ferndale, WashingtonProcess
Number Emission Unit
ID Emission Unit Description Visibility Impairing
Pollutants Existing
Pollution Controls Modeling Source Type Table 3-1 Primary Aluminum Reduction Emission Units
Alcoa Intalco Works Ferndale, Washington

5 238 Auxiliary diesel generators PM, SO
x , NO
x Volume (combined)

6 3, 6, 9, 12, 15 Casting pit steam exhaust stacks PM Volume (combined)

6 21 Pigger cooling conveyor exhaust stack PM Volume (combined)

6 220a, 220b, 221a, 221b MHD holding furnaces PM Volume (combined)

6 266 Casthouse monitor roof PM Volume (combined)

6 269 Pigger aluminum furnace door exhaust hood PM Volume (combined)

6 315 Dross/silicon storage baghouse PM Fabric Filter Volume (combined)

7 196 Primary WTP reclaimed storage silo baghouse stack PM Fabric Filter Volume (combined)

7 206 Pangborn baghouse stack PM Fabric Filter Volume (combined)

7 207 Annex paste plant baghouse stack PM Fabric Filter Volume (combined)

7 211 Alumina ore silo #1 baghouse stack PM Fabric Filter Volume (combined)

7 212 Alumina ore silo #2 baghouse stack PM Fabric Filter Volume (combined)

7 213 Alumina ore silo #3 baghouse stack PM Fabric Filter Volume (combined)

7 214 Alumina ore silo #4 railcar unloader baghouse stack PM Fabric Filter Volume (combined)

7 215 Alumina ore pier-head transfer point baghouse stack PM Fabric Filter Volume (combined)

7 216 Alumina ore ship unloading baghouse stack PM Fabric Filter Volume (combined)

7 226 Aluminum fluoride silo baghouse stack PM Fabric Filter Volume (combined)

7 228 Covered annex bunkers for crust and digout PM Volume (combined)

7 229 Brick crushing facility baghouse stack PM Fabric Filter Volume (combined)

7 274 Alumina silo #4 truck loader baghouse stack PM Fabric Filter Volume (combined)

7 275 Aluminum fluoride/anthracite railcar unloading fugitive dust PM Volume (combined)

7 276 Coke unloading and transfer fugitive dust PM Volume (combined)

7 281 Annex ramming paste area roof vents PM Volume (combined)

7 284 Annex west pitch melter stack PM Volume (combined)

7 285 Annex east pitch melter stack PM Volume (combined)

7 286 Annex ramming paste mixer stack PM Volume (combined)

7 287 Autogenous mill silo baghouse stack PM Fabric Filter Volume (combined)

7 293 Baghouse hopper unloading PM Volume (combined)

7 295 Landfill - solid waste PM Volume (combined)

7 296 Landfill - RCRA waste PM Volume (combined)

7 306 Alumina ore ship unloader clamshell PM Volume (combined)

8 222 Paint shop shot blaster baghouse stack PM Fabric Filter Volume (combined)LCCCoordinateXLCCCoordinateYStackHeightBaseElevationEffectiveStackDiameterExitVelocityFlowRateExitTemperaturePM10EmissionRateFilterablePM2.5EmissionRateCondensablePM2.5EmissionRateSO2EmissionRateNOxEmissionRate(km) (km) (m) (m) (m) (m/s)(m3/s)(°K) (g/s) (g/s) (g/s) (g/s) (g/s)DSA1 -120.536 -14.914 19.8 65.4 3.733 12.98 142.1 363.7 1.81 0.097 1.48 37.41DSA2 -120.466 -15.150 19.8 63.9 3.733 13.05 142.8 363.7 1.81 0.097 1.48 37.41DSB3 -120.691 -14.958 17.9 62.2 5.957 5.17 144.1 353.1 1.81 0.097 1.48 37.41DSB4 -120.621 -15.195 17.9 61.4 5.957 5.17 144.1 353.1 1.81 0.097 1.48 37.41DSC5 -120.840 -15.000 17.9 59.7 5.723 4.90 126.0 355.1 1.81 0.097 1.48 37.41DSC6 -120.770 -15.238 17.9 59.0 5.723 4.79 123.2 355.1 1.81 0.097 1.48 37.41BAKEOVEN -121.011 -15.391 25.5 57.5 2.129 12.98 46.2 369.4 0.35 0.15 0.15 5.22 3.91CAST1-6 -120.392 -15.061 26.9 66.1 2.365 5.69 25.0 433.0 0.33 0.079 0.13CAST7-8 -120.415 -14.965 23.2 66.1 1.365 5.69 8.3 433.0 0.11 0.026 0.045CAST9-10 -120.422 -14.960 18.4 66.1 1.365 5.69 8.3 433.0 0.11 0.026 0.045CAST11-12 -120.433 -14.922 23.2 66.1 1.365 5.69 8.3 433.0 0.11 0.026 0.045188 -120.933 -15.393 36.1 58.5 1.462 5.34 9.0 Ambient 0.010 0.010189 -120.919 -15.088 36.1 58.5 1.287 3.63 4.7 Ambient 0.090 0.090191 -120.940 -15.395 36.1 58.5 1.287 3.63 4.7 Ambient 0.090 0.090195 -120.553 -15.394 17.7 63.1 0.61 4.29 1.3 343.0 0.080 0.080198 -120.957 -15.122 13.3 58.5 1.219 20.23 23.6 Ambient 0.24 0.24199 -120.953 -15.121 13.3 58.5 1.219 20.23 23.6 Ambient 0.24 0.24208 -121.006 -15.002 5.0 58.5 1.828 2.53 6.6 Ambient 0.076 0.076209 -121.095 -14.985 15.7 74.4 0.914 36.19 23.7 Ambient 0.43 0.43210 -120.400 -15.282 9.4 65.2 0.762 3.11 1.4 395.0 0.00018 0.00018217 -120.360 -15.210 23.2 77 1.365 5.69 8.3 433.0 0.026 0.0035 0.0070232 -120.931 -15.423 6.6 58.2 0.61 29.12 8.5 Ambient 0.097 0.097260 -120.925 -15.134 11 59.1 0.26 1.46 0.08 Ambient 0.025 0.025312 -120.922 -15.099 13.7 58.5 0.49 1.59 0.30 370.0 0.11 0.11313 -120.941 -15.104 13.7 58.5 0.49 1.59 0.30 370.0 0.11 0.11316 -120.858 -15.400 22.86 57.96 1.372 15.9 23.5 302.9 0.30 0.30SourceDescriptionTable 4-1Source Input Data for Baseline Modeling - Point SourcesAlcoa Intalco WorksFerndale, WashingtonRoof Scrubber Water On ConditionsLCCCoordinateBegin XLCCCoordinateBegin YLCCCoordinateEnd XLCCCoordinateEnd YReleaseHeightBaseElevationLineSourceWidthExitVelocityFlowRateBuoyancyParameterPM10EmissionRateFilterablePM2.5EmissionRateCondensablePM2.5EmissionRateSO2EmissionRateNOxEmissionRate(km) (km) (km) (km) (m) (m) (m) (m/s)(m3/s) (m4/s3)(g/s) (g/s) (g/s) (g/s) (g/s)WSLINEA1 -120.532 -14.845 -120.422 -15.219 16.40 65.4 4.24 3.920 55.32 410.22 2.30 0.87 0.83 1.97 0.00WSLINEA2 -120.606 -14.867 -120.496 -15.241 16.40 64.1 4.24 3.920 55.32 410.22 2.30 0.87 0.83 1.97 0.00WSLINEB1 -120.681 -14.892 -120.571 -15.266 16.40 62.9 4.24 3.990 56.30 417.52 2.30 0.87 0.83 1.97 0.00WSLINEB2 -120.755 -14.914 -120.645 -15.288 16.40 61.7 4.24 3.990 56.30 417.52 2.30 0.87 0.83 1.97 0.00WSLINEC1 -120.828 -14.936 -120.719 -15.309 16.40 60.5 4.24 3.904 55.08 408.49 2.30 0.87 0.83 1.97 0.00WSLINEC2 -120.903 -14.958 -120.793 -15.332 16.40 59.3 4.24 3.904 55.08 408.49 2.30 0.87 0.83 1.97 0.00Roof Scrubber Water Off ConditionsLCCCoordinateBegin XLCCCoordinateBegin YLCCCoordinateEnd XLCCCoordinateEnd YReleaseHeightBaseElevationLineSourceWidthExitVelocityFlowRateBuoyancyParameterPM10EmissionRateFilterablePM2.5EmissionRateCondensablePM2.5EmissionRateSO2EmissionRateNOxEmissionRate(km) (km) (km) (km) (m) (m) (m) (m/s)(m3/s) (m4/s3)(g/s) (g/s) (g/s) (g/s) (g/s)WSLINEA1 -120.532 -14.845 -120.422 -15.219 16.40 65.4 4.24 3.920 55.32 860.33 11.94 4.48 4.29 1.97 0.00WSLINEA2 -120.606 -14.867 -120.496 -15.241 16.40 64.1 4.24 3.920 55.32 860.33 11.94 4.48 4.29 1.97 0.00WSLINEB1 -120.681 -14.892 -120.571 -15.266 16.40 62.9 4.24 3.990 56.30 875.62 11.94 4.48 4.29 1.97 0.00WSLINEB2 -120.755 -14.914 -120.645 -15.288 16.40 61.7 4.24 3.990 56.30 875.62 11.94 4.48 4.29 1.97 0.00WSLINEC1 -120.828 -14.936 -120.719 -15.309 16.40 60.5 4.24 3.904 55.08 856.70 11.94 4.48 4.29 1.97 0.00WSLINEC2 -120.903 -14.958 -120.793 -15.332 16.40 59.3 4.24 3.904 55.08 856.70 11.94 4.48 4.29 1.97 0.00SourceDescriptionSourceDescriptionTable 4-2Source Input Data for Baseline Modeling - Line SourcesAlcoa Intalco WorksFerndale, WashingtonSouthwestCorner LCCCoordinate XSouthwestCorner LCCCoordinate YReleaseHeightInitialσzBaseElevationTotalAreaPM10EmissionRateFilterablePM2.5EmissionRateCondensablePM2.5EmissionRateSO2EmissionRateNOxEmissionRate(km) (km) (m) (m) (m)(m2) (g/s/m2) (g/s/m2) (g/s/m2) (g/s/m2) (g/s/m2)239 Fugitive dust from vehicle travel on paved roads -120.536 -14.914 5 10 60 720,000 0.00000040 0.000000059 0 0 0241 Facility-wide natural gas combustion (fugitive) -120.466 -15.150 15 15 60 720,000 0.00000022 0.00000022 0 0.000000042 0.0000030273 Alumina ore handling fugitive dust -120.691 -14.958 15 15 60 720,000 0.000000053 0.0000000080 0 0 0SourceIDSource DescriptionTable 4-3Source Input Data for Baseline Modeling - Area SourcesAlcoa Intalco WorksFerndale, WashingtonReferenceLCCCoordinateXReferenceLCCCoordinateYReleaseHeightInitialσyInitialσzBaseElevationPM10EmissionRateFilterablePM2.5EmissionRateCondensablePM2.5EmissionRateSO2EmissionRateNOxEmissionRate(km) (km) (m) (m) (m) (m) (g/s) (g/s) (g/s) (g/s) (g/s)251 Anode bake building monitor roof -120.982 -15.242 22 33.7 10.2 58.7 0.13 0.13 0.00 0.00 0.00252 Anode block hole blower -120.982 -14.242 22 33.7 10.2 58.7 0.12 0.12 0.00 0.00 0.00257A Rod shop crust recovery discharge to trucks from bins #1 and #2 -120.948 -15.123 4.6 1.07 1.07 58.5 0.0021 0.00032 0.00 0.00 0.00257B Rod shop crust recovery discharge to trucks from bins #1 and #2 -120.906 -15.112 4.6 1.07 1.07 58.5 0.0021 0.00032 0.00 0.00 0.00259A Rod shop carbon recovery discharge to trucks from bins #1 and #2 -120.948 -15.123 4.6 1.07 1.07 58.5 0.0030 0.00046 0.00 0.00 0.00259B Rod shop carbon recovery discharge to trucks from bins #1 and #2 -120.906 -15.112 4.6 1.07 1.07 58.5 0.0030 0.00046 0.00 0.00 0.00280 Annex cathode assembly area roof vent -120.983 -15.013 18.3 8.97 8.51 58.5 0.054 0.054 0.00 0.00 0.00282 Annex ladle rebuild area rood vents -120.952 -14.99 18.3 8.97 8.51 58.5 0.38 0.38 0.00 0.00 0.00Others1Other sources smaller than 0.1 g/s, combined (no SOxor NOx)-120.665 -15.076 4.6 1.07 1.07 62.0 0.358 0.307 0.00 0.00 0.00Others2Other sources greater than 0.1 g/s, combined (no SOxor NOx)-120.665 -15.076 4.6 1.07 1.07 62.0 0.849 0.7414 0.00 0.00 0.00Others3Other sources, combined (with SOxor NOxemissions)-120.665 -15.076 4.6 1.07 1.07 62.0 0.1722 0.1676 0.00 0.1574 2.348SourceIDSource DescriptionTable 4-4Source Input Data for Baseline Modeling - Volume SourcesAlcoa Intalco WorksFerndale, WashingtonModeled 98th Percentile Modeled 98th Percentile Modeled 98th Percentile

(deciview) (deciview) (deciview)

Alpine Lakes Wilderness Area 1.244 36 0.965 37 0.881 23
Goat Rock Wilderness Area 0.500 8 0.579 10 0.317 3
Glacier Peak Wilderness Area 1.161 37 1.156 38 0.736 23
Mount Adams Wilderness Area 0.456 7 0.472 6 0.357 2
Mount Rainier National Park 0.843 22 1.052 26 0.629 15
North Cascades National Park 1.376 65 1.395 56 1.138 32 Olympic National Park 2.363 59 1.858 53 2.136 45 Pasayten Wilderness Area 0.866 30 0.871 33 0.659 13

Note: 2003

Number of Days Exceeding

0.5 dv 2004

Number of Days Exceeding

0.5 dv

Modeled visibility impacts that exceed the 0.5 dv contribution threshold are presented in bold in this table. Table 4-5 Screening Baseline Visibility Modeling Results Alcoa Intalco Works Ferndale, Washington

Class I Area 2005

Number of Days Exceeding

0.5 dvModeled 98th Percentile Modeled 98th Percentile Modeled 98th Percentile

(deciview) (deciview) (deciview)

Alpine Lakes Wilderness Area 0.738 24 0.742 18 0.632 9
Goat Rock Wilderness Area 0.332 4 0.287 5 0.194 0
Glacier Peak Wilderness Area 0.916 24 0.769 25 0.552 10
Mount Rainier National Park 0.660 11 0.574 9 0.414 3
North Cascades National Park 0.936 36 0.986 35 0.693 14 Olympic National Park 1.527 41 1.369 37 1.225 34 Pasayten Wilderness Area 0.448 6 0.469 6 0.412 2

Note: Table 4-6 Refined Baseline Visibility Modeling Results Alcoa Intalco Works Ferndale, Washington

Modeled visibility impacts that exceed the 0.5 dv contribution threshold are presented in bold in this table. Class I Area 2005

Number of Days Exceeding

0.5 dv 2003

Number of Days Exceeding

0.5 dv 2004

Number of Days Exceeding

0.5 dvModeled 98thPercentile(deciview)SO4NO3FilterablePM2.5Coarse PMCondensablePMTotal of all sources1.527 92.5% 3.0% 0.5% 0.5% 3.4%Potline primary emission controls1.414 96.6%0% 0.05% 0.3% 3.2%Potline secondary emission controls 0.026 67.6% 0% 5% 5.4% 21.6%Anode bake furnace0.048 59.4% 39.1%0% 0% 1.4%Casthouse stacks 0.002 0% 0% 0% 0% 66.7%All other stacks 0.003 0% 0% 80.0% 20.0% 0%All volume sources 0.022 6.3% 75.0% 12.5% 6.3% 0%All area sources 0.011 0% 93.8% 0% 0% 0%Total of all sources1.369 80.8% 4.4% 1.7% 2.4% 10.6%Potline primary emission controls1.142 90.6%0% 0.12% 1.1% 8.2%Potline secondary emission controls 0.124 40.4% 0% 10.1% 11.8% 37.6%Anode bake furnace0.053 40.8% 55.3%1.3% 1.3% 2.6%Casthouse stacks 0.004 0% 0% 16.7% 16.7% 66.7%All other stacks 0.006 0% 0% 66.7% 33.3% 0%All volume sources 0.025 2.8% 69.4% 16.7% 11.1% 0%All area sources 0.014 0% 95.0% 5.0% 5.0% 0%Total of all sources1.225 90.3% 2.5% 0.95% 0.89% 5.3%Potline primary emission controls1.080 95.7%0% 0% 0% 3.9%Potline secondary emission controls 0.079 61.5% 0% 7.3% 5.5% 26.6%Anode bake furnace0.039 62.3% 34.0%0% 0% 1.9%Casthouse stacks 0.001 0% 0% 0% 0% 100.0%All other stacks 0.003 0% 0% 75.0% 25.0% 0%All volume sources 0.016 4.5% 68.2% 13.6% 9.1% 0%All area sources 0.007 0% 90.0% 0% 0% 0%200320042005Year Source GroupPercentage of Species ContributionTable 4-7Culpability Analysis for Refined Baseline Visibility Modeling Results in Olympic National ParkAlcoa Intalco WorksFerndale, WashingtonRBLC ID FacilityLastUpdateProcess Pollutant Control OptionPercentEfficiencyEmission LimitKY-0070NSA - A Division ofSouthwire Company03/02/2004 Potline 5SO2Wet scrubber193% 25.51 lb/hrSC-0037 Alumax of South Carolina 09/17/2002 Potroom Groups (4) PM Existing dry alumina scrubbers (fabric filter) 5.9 lb/hrSC-0037 Alumax of South Carolina 09/17/2002 Potroom Groups (4)SO2Limit maximum % sulfur of anode coke to 2.95%;limit maximum % sulfur of anode pitch to 1.2%271 lb/hrSC-0037 Alumax of South Carolina 09/17/2002 Anode Bake PlantSO2No upgrade; limit maximum % sulfur of anodecoke to 2.95%; limit maximum % sulfur of anodepitch to 1.2%85.5 lb/hrSC-0037 Alumax of South Carolina 09/17/2002 Anode Bake Plant PM No upgrade; limit sulfur content of raw materials 4.8 lb/hrSC-0037 Alumax of South Carolina 09/17/2002 Anode Bake PlantNOxNo upgrade; limit sulfur content of raw materials 9 lb/hrKY-0041 Arco Metals Co. 12/18/2001Primary AluminumReduction PotlinePM Baghouse, hooding for raw material handling 98% 0.02 gr/dscfKY-0041 Arco Metals Co. 12/18/2001Primary AluminumReduction PotlineSO2Fuel spec: low sulfur coke and pitch (calc. 3%sulfur)388 lb/hrOR-0002 Alumax Pacific Corp. 12/18/2001 Entire Plant PM Baghouse5.4 lb/t (monthly ave.);5.0 lb/ton (annual ave.)OR-0002 Alumax Pacific Corp. 12/18/2001 Anode CokeSO2Fuel spec: sulfur limit in coke 3% S in cokeWA-0003 Alcoa 12/18/2001 Potlines 1, 2, and 3SO2Fuel spec: limit S content in coke, raw 3% S in cokeNC-0003 Alcoa 01/28/2002 Potline 3 PM Fabric filter 26 lb/hrNC-0003 Alcoa 01/28/2002 Potline 3SO2321 lb/hrNC-0003 Alcoa 01/28/2002 Anode ProductionSO213 lb/hrNC-0003 Alcoa 01/28/2002 Anode Production PM 9 lb/hrMO-0036 Noranda Aluminum, Inc. 05/09/2006Carbon BakingFurnace for Potline 3PM1098.6 tons/yrMO-0036 Noranda Aluminum, Inc. 05/09/2006 Potline 1PM10Coated filter dry scrubber 56.76 tons/yrMO-0036 Noranda Aluminum, Inc. 05/09/2006 Potline 3PM10Coated filter dry scrubber 68.8 tons/yrNote:1This wet scrubber is not actually used or required by permit.Table 5-1RBLC Database Search Results for Primary Aluminum FacilitiesAlcoa Intalco WorksFerndale, WashingtonEmissions Emissions Emissions Emissions(tons/yr) (tons/yr) (tons/yr) (tons/yr)1LSFO Scrubber forPotlines854 88 136 0 984 (42) 1,113 (28)2LSFO Scrubber forAnode Bake Furnace6,904 2 136 0 747 (8) 921 (6)CurrentAllowableEmissionsOperating Limit of3% Sulfur in Coke7,076 136 693 869Notes:NOxSO2Table 5-2Post Control Emission Rates1Alcoa Intalco WorksFerndale, Washington% Reduction(Increase)21Emission rates include the potline primary control system, the potline secondary control system emissions, and the anode bakefurnaceemissions.2Compared with current potential emissions.PM2.5PM10% Reduction(Increase)2% Reduction(Increase)2% Reduction(Increase)2ControlScenarioSO2ControlTechnologyControlScenarioControlTechnologyEvaluatedControlledSO2EmissionRate1(tons/year)SO2EmissionReductions2(tons/year)InstalledCapital CostTotalAnnualizedControlCostsCostEffectiveness(per ton SO2removed)EnergyImpact(kW-hr/yr)291tons/yr PM2.527,130 tons/year of solid waste disposal243tons/yr PM10182.5 million gallons/year makeup water17,597tons/yr GHG354tons/yr PM2.5639.5 tons/year of solid waste disposal52tons/yr PM2.512.8 million gallons/year makeup water1,330tons/yr GHG3CurrentAllowableEmissionsOperating Limitof 3% Sulfur inCoke7,076Notes:3Greenhouse gas (GHG) emissions are presented as CO2equivalent emissions. The GHG emission calculations are presented in Appendix E.Non-Air Quality EnvironmentalImpactsTable 5-3Summaryof the Impacts Analysis for SO2Control ScenariosAlcoa Intalco WorksFerndale, WashingtonCollateral Increasein Other Pollutants1Emission rates include the potline primary control system, the potline secondary control system emissions, and the anode bakefurnace emissions.2Compared with current potential emissions.12LSFO Scrubberfor PotlinesLSFO Scrubberfor Anode BakeFurnace8546,9046,223172 $29,482,194$234,531,0496,570,00064,824,000$46,820,000$6,277,000$7,500$36,400LCCCoordinateXLCCCoordinateYStackHeightBaseElevationEffectiveStackDiameterExitVelocityExitTemperaturePM10EmissionRateFilterablePM2.5EmissionRateCondensablePM2.5EmissionRateSO2EmissionRateNOxEmissionRate(km) (km) (m) (m) (m) (m/s) (°K) (g/s) (g/s) (g/s) (g/s) (g/s)1LSFO Scrubber forPotlinesPotline WetScrubber2-120.425 -15.316 38.1 59.0 8.1 18.3 310 0.00 17.8 0.00 11.22 0.002LSFO Scrubber forAnode Bake FurnaceAnode Bake FurnaceWet Scrubber3-121.018 -15.614 30.5 57.5 2.6 18.3 336 0.00 1.70 0.15 0.26 3.91Notes:1Source input data for all other sources are the same as listed in Table 4-1 through 4-4 for the baseline modeling.2Potline wet scrubber source replaces sources DSA1, DSA2, DSB3, DSB4, DSC5, and DSC6 in Table 4-1 from the baseline modeling.3Anode bake oven wet scrubber source replaces source BAKEOVEN in Table 4-1 from the baseline modeling.ControlScenarioSO2ControlTechnologySource DescriptionTable 5-4Source Input Data for Post Control SO2Modeling1Alcoa Intalco WorksFerndale, WashingtonModeled98thPercentileModeled98thPercentileModeled98thPercentile(deciview) (deciview) (deciview)Alpine Lakes Wilderness Area 0.158 0 0.147 0 0.129 0Glacier Peak Wilderness Area 0.190 0 0.163 0 0.125 0Mount Rainier National Park 0.108 0 0.107 0 0.085 0North Cascades National Park 0.198 0 0.212 0 0.174 0Olympic National Park 0.355 2 0.303 1 0.325 1Alpine Lakes Wilderness Area0.723220.729180.6219Glacier Peak Wilderness Area0.901240.752230.54610Mount Rainier National Park0.648110.5659 0.410 3North Cascades National Park0.921360.974340.68414Olympic National Park1.503411.348371.20633Alpine Lakes Wilderness Area0.738240.742180.6329Glacier Peak Wilderness Area0.916240.769250.55210Mount Rainier National Park0.660110.5749 0.414 3North Cascades National Park0.936360.986350.69314Olympic National Park1.527411.369371.22534Note:Table 5-5SO2Post Control VisibilityModelingResultsAlcoa Intalco WorksFerndale, WashingtonControlScenarioSO2ControlTechnologyEvaluatedClass I Area2005Number ofDaysExceeding0.5 dv2003Number ofDaysExceeding0.5 dv2004Number ofDaysExceeding0.5 dvCurrentAllowableEmissionsOperating Limit of3% Sulfur in CokeModeled visibility impacts that exceed the 0.5 dv contribution threshold are presented in bold in this table.LSFO Scrubber forPotlines12LSFO Scrubber forAnode Bake Furnace

# APPENDICES

# A PPENDIX 

# A:

BART M ODELING 

# R ESULTS

# A PPENDIX 

# B:

B USINESS 

# C ONFIDENTIAL 

# I NFORMATION

# A PPENDIX 

# C:

P RE 

# -F EASIBILITY 

# R EPORT

# A PPENDIX 

# D:

W ET 

# S CRUBBER 

# E CONOMIC AND 

# E NERGY 

# I MPACTPotlinesAnode BakeFurnaceVendor Quote#1Vendor Quote#2Average PotlinesAnode BakeFurnaceReagent feed system 10% 0.33 0.80 $6,500,000 $8,200,000 $7,350,000 $7,894,009 $404,491SO2removal system35% 0.50 0.80 $22,750,000 $28,700,000 $25,725,000 $28,543,995 $4,666,407Flue gas system 30% 0.50 0.80 $19,500,000 $24,600,000 $22,050,000 $24,466,281 $3,999,778By-product handling system 10% 0.40 0.80 $6,500,000 $8,200,000 $7,350,000 $8,104,759 $403,121General support equipment 15% 0.15 0.80 $9,750,000 $12,300,000 $11,025,000 $11,436,638 $568,845TOTAL $65,000,000 $82,000,000 $73,500,000 $80,445,682 $10,042,642Scaling of Capital Equipment Costs Based on Vendor ProposalsIntalco WorksFerndale, WashingtonIntalco Scrubber EquipmentCost EstimatesFraction ofTotalEquipmentCostScrubber ComponentScaling EquationExponentTennessee Potline Scrubber Equipment CostsBART cost calculations 110607.xls-Capital equipment costsE N V I R O NPotlines

Intalco Works Ferndale, Washington

Value Notes/References Capital Investment Costs

Direct Capital Costs (DCC)

Purchased Equipment Costs (PEC)

Adsorber vessels with internals $80,445,682 Based on vendor quotations for Tennessee Alcoa smelter, adjusted for scrubber exhaust gas flow rate, limestone consumption, and gypsum generation per Pre-feasability Report (Hatch 2007)

Pumps Included Limestone prep Included Dewatering systems Included
Fans Included
Inlet ductwork Included
Stacks Included Continuous Emission Monitoring system (2 stacks) $80,000 Subtotal (EC) $80,525,682

Instrumentation $4,026,284 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of EC; adjusted from 10% since basic instrumentation is included in proposal)

Sales tax $5,234,169 State sales tax rate for Washington is 6.5% Freight $4,026,284 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of EC)
Total Purchased Equipment Costs (PEC) $93,812,419

Direct Installation Costs (DIC)

Foundations and supports $11,257,490 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (12% of PEC) Handling and erection $75,049,936 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (80% of PEC; adjusted from 40% to account for retrofit of existing plant and onsite fabrication)

Electrical $938,124 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Piping $28,143,726 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (30% of PEC) Insulation $938,124 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Painting $938,124 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC)

Total Direct Installation Costs (DIC) $117,265,524
Total Direct Capital Costs $211,077,944 Sum of PEC and DIC

Indirect Capital Costs (ICC)
Engineering $4,690,621 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of PEC; adjusted from 10% since vendor proposal includes an allowance for engineering)

Construction and field expenses $9,381,242 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (10% of PEC) Contractor fees $4,690,621 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of PEC; adjusted from 10% based on assumption that vendor will oversee scrubber installation) Start-up $938,124 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Performance test $938,124 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Contingencies $2,814,373 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (3% of PEC)

Total Indirect Capital Costs $23,453,105

Total Capital Investment Costs (TCIC) $234,531,049 Sum of DCC and ICC

References:
Hatch. 2007. SO 2 Scrubbing for the INTALCO Primary Aluminum Smelter: Pre-Feasibility Report . July 26.
USEPA. 2002. EPA Air Pollution Control Cost Manual , Sixth Edition. EPA/452/B-02-001. January. Captial Investment Cost Analysis for SO 2 Control Using a Wet Scrubber

BART cost calculations 110607.xls-Capital cost calcs (potlines) E N V I R O NPotlines

Intalco Works Ferndale, Washington

Value Units Notes/References Annual Operation and Maintenance Costs

Direct Annual Costs (DAC)

Operating labor Operator $324,120 Assumes $37 per hour with one full-time operator, 3 shifts per day Supervisor $48,618 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (15% of operator costs)

Water $96,725 Water usage 500,000 gal/day Pre-feasability Report (Hatch 2007) Cost of water $0.00053 $/gal Intalco controller

Limestone $470,052 Limestone usage 14,244 tons/yr Pre-feasability Report (Hatch 2007) Cost of limestone $33 $/ton Assumes $28/ton for 8 mesh size limestone plus $5/ton for shipping by barge

Compressed air $18,922 Compressed air usage 150 scfm Pre-feasability Report (Hatch 2007) Cost of compressed air $0.24 $/1000 scf Average compressed air generation cost for industrial facilities (http://www1.eere.energy.gov/industry/bestpractices/pdfs/com pressed_air1.pdf)

Gypsum disposal $3,933,809 Gypsum generation rate 6,194 lb/hr Pre-feasability Report (Hatch 2007) Cost of gypsum disposal $145 $/ton Non-hazardous waste disposal and transportation costs

Maintenance Labor $673,920 Assumes $45 per hour with 4 full-time maintenance personnel, one shift per day, 5 days per week and 1 maintenance personnel for all other shifts Material $1,303,000 Cost for low sulfur boiler system with 1.7 macfm inlet/1.5 macfm outlet, which is smaller than the potline system with 2.2 macfm inlet/2.0 macfm outlet (Sargent & Lundy LLC 2003)

Electricity $3,409,742 Electricity usage 7,400 kWh/hr Pre-feasability Report (Hatch 2007) Electricity cost $0.0526 $/kWh Facility average power rate for 2007 (Intalco controller)

Total Direct Annual Costs $10,278,908

Indirect Annual Costs (IAC)
Overhead $1,409,795 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (60% of total labor and maintenance material costs)

General and administrative costs $4,690,621 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (2% of TCIC)

Property tax $2,345,310 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (1% of TCIC)

Insurance $2,345,310 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (1% of TCIC)

Total Indirect Annual Costs $10,791,037 Sum of PEC and DIC

Total Annual Operating and Maintenance Costs $21,069,945 Sum of DAC and IAC

References:
Hatch. 2007. SO 2 Scrubbing for the INTALCO Primary Aluminum Smelter: Pre-Feasibility Report . July 26. Sargent & Lundy LLC. 2003. Wet Flue Gas Desulfurization Technology Evaluation . Prepared for National Lime Association. January.
USEPA. 2002. EPA Air Pollution Control Cost Manual , Sixth Edition. EPA/452/B-02-001. January. Operation and Maintenance Cost Analysis for SO 2 Control Using a Wet Scrubber

BART cost calculations 110607.xls-O&M cost calcs (potlines) E N V I R O NInstallation of Wet Scrubber on Potline ExhaustReferencePotline hooding capture efficiency 95%Total potline uncontrolled SOxemission rate37,780 lb/dayTotal potline SOxemission limitPrimary potline control system uncontrolled SOxemission rate35,891 lb/day Calculated based on potline hooding capture efficiencySOxcontrol efficiency95%Controlled SOxemission rate1,795 lb/dayUncontrolled annual SOxemissions6,550 tpyControlled annual SOxemissions328 tpySOxreduction6,223 tpyDirect capital costs (DCC) 211,077,944$Indirect capital costs (ICC) 23,453,105$Total capital costs 234,531,049$Interest rate 7% USEPA 2002, Section 1, Chapter 2.4.2Period of annualization 15 years AssumptionCapital recovery discount factor 0.11 USEPA 2002, Section 1, Chapter 2.4.4.4, Equation 2.8aAnnualized capital cost 25,750,000$USEPA 2002, Section 1, Chapter 2.4.4.4, Equation 2.8Operating labor costs 324,120$Supervisory labor costs 48,618$Maintenance labor costs 673,920$Maintenance material costs 1,303,000$Electricity costs 3,409,742$Water costs 96,725$Limestone costs 470,052$Compressed air costs 18,922$Gypsum disposal costs 3,933,809$Overhead 1,409,795$Property tax 2,345,310$Insurance 2,345,310$General and administrative costs 4,690,621$Total annual cost estimate 46,820,000$Cost of option per ton SOxreduced7,500$BART cost calculations 110607.xls-Potline scrubber cost summaryE N V I R O NCaptial Investment Cost Analysis for SO 2 Control Using a Wet Scrubber

Anode Bake Furnace

Intalco Works Ferndale, Washington

Value Notes/References Capital Investment Costs

Direct Capital Costs (DCC)

Purchased Equipment Costs (PEC)

Adsorber vessels with internals $10,042,642 Based on vendor quotations for Tennessee Alcoa smelter, adjusted for exhaust gas flow rate per Pre-feasability Report (Hatch 2007)

Pumps Included Limestone prep Included Dewatering systems Included
Fans Included
Inlet ductwork Included
Stacks Included Continuous Emission Monitoring system (2 stacks) $80,000 Subtotal (EC) $10,122,642

Instrumentation $506,132 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of EC; adjusted from 10% since basic instrumentation is included in proposal)

Sales tax $657,972 State sales tax rate for Washington is 6.5% Freight $506,132 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of EC)
Total Purchased Equipment Costs (PEC) $11,792,878

Direct Installation Costs (DIC)

Foundations and supports $1,415,145 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (12% of PEC) Handling and erection $9,434,302 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (80% of PEC; adjusted from 40% to account for retrofit of existing plant and onsite fabrication)

Electrical $117,929 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Piping $3,537,863 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (30% of PEC) Insulation $117,929 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Painting $117,929 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC)

Total Direct Installation Costs (DIC) $14,741,097
Total Direct Capital Costs $26,533,975 Sum of PEC and DIC

Indirect Capital Costs (ICC)
Engineering $589,644 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of PEC; adjusted from 10% since vendor proposal includes an allowance for engineering)

Construction and field expenses $1,179,288 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (10% of PEC) Contractor fees $589,644 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (5% of PEC; adjusted from 10% based on assumption that vendor will oversee scrubber installation) Start-up $117,929 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Performance test $117,929 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (1% of PEC) Contingencies $353,786 USEPA 2002, Section 5.2, Chapter 1, Table 1.3 (3% of PEC)

Total Indirect Capital Costs $2,948,219

Total Capital Investment Costs (TCIC) $29,482,194 Sum of DCC and ICC

References:
Hatch. 2007. SO 2 Scrubbing for the INTALCO Primary Aluminum Smelter: Pre-Feasibility Report . July 26.
USEPA. 2002. EPA Air Pollution Control Cost Manual , Sixth Edition. EPA/452/B-02-001. January.

BART cost calculations 110607.xls-Capital cost calcs (ABF) E N V I R O NOperation and Maintenance Cost Analysis for SO 2 Control Using a Wet Scrubber

Anode Bake Furnace

Intalco Works Ferndale, Washington

Value Units Notes/References Annual Operation and Maintenance Costs

Direct Annual Costs (DAC)

Operating labor Operator $324,120 Assumes $37 per hour with one full-time operator, 3 shifts per day Supervisor $48,618 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (15% of operator costs)

Water $6,771 Water usage 35,000 gal/day Pre-feasability Report (Hatch 2007) Cost of water $0.00053 $/gal Intalco controller

Limestone $11,286 Limestone usage 342 tons/yr Pre-feasability Report (Hatch 2007) Cost of limestone $33 $/ton Assumes $28/ton for 8 mesh size limestone plus $5/ton for shipping by barge

Compressed air $6,307 Compressed air usage 50 scfm Pre-feasability Report (Hatch 2007) Cost of compressed air $0.24 $/1000 scf Average compressed air generation cost for industrial facilities (http://www1.eere.energy.gov/industry/bestpractices/pdfs/com pressed_air1.pdf)

Gypsum disposal $92,725 Gypsum generation rate 146 lb/hr Pre-feasability Report (Hatch 2007) Cost of gypsum disposal $145 $/ton Non-hazardous waste disposal and transportation costs

Maintenance Labor $336,960 Assumes $45 per hour with 2 full-time maintenance personnel, one shift per day, 5 days per week and a half-time maintenance personnel equivalent for all other shifts

Material $163,796 Calculated based on estimated maintenance material costs for

p otline scrubber and ratio of purchased equipment costs for the anode bake furnace and potline scrubbers

Electricity $345,582 Electricity usage 750 kWh/hr Pre-feasability Report (Hatch 2007) Electricity cost $0.0526 $/kWh Facility average power rate for 2007 (Intalco controller)

Total Direct Annual Costs $1,336,165

Indirect Annual Costs (IAC)
Overhead $524,097 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (60% of total labor and maintenance material costs)

General and administrative costs $589,644 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (2% of TCIC)

Property tax $294,822 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (1% of TCIC)

Insurance $294,822 USEPA 2002, Section 5.2, Chapter 1, Table 1.4 (1% of TCIC)

Total Indirect Annual Costs $1,703,384 Sum of PEC and DIC

Total Annual Operating and Maintenance Costs $3,039,549 Sum of DAC and IAC

References:
Hatch. 2007. SO 2 Scrubbing for the INTALCO Primary Aluminum Smelter: Pre-Feasibility Report . July 26.
USEPA. 2002. EPA Air Pollution Control Cost Manual , Sixth Edition. EPA/452/B-02-001. January.

BART cost calculations 110607.xls-O&M cost calcs (ABF) E N V I R O NInstallation of Wet Scrubber on Anode Bake Furnace ExhaustReferenceUncontrolled SOxemission rate994 lb/daySOxcontrol efficiency95%Controlled SOxemission rate50 lb/dayUncontrolled annual SOxemissions181 tpyControlled annual SOxemissions9 tpySOxreduction172 tpyDirect capital costs (DCC) 26,533,975$Indirect capital costs (ICC) 2,948,219$Total capital costs 29,482,194$Interest rate 7% USEPA 2002, Section 1, Chapter 2.4.2Period of annualization 15 years AssumptionCapital recovery discount factor 0.11 USEPA 2002, Section 1, Chapter 2.4.4.4, Equation 2.8aAnnualized capital cost 3,237,000$USEPA 2002, Section 1, Chapter 2.4.4.4, Equation 2.8Operating labor costs 324,120$Supervisory labor costs 48,618$Maintenance labor costs 336,960$Maintenance material costs 163,796$Electricity costs 345,582$Water costs 6,771$Limestone costs 11,286$Compressed air costs 6,307$Gypsum disposal costs 92,725$Overhead 524,097$Property tax 294,822$Insurance 294,822$General and administrative costs 589,644$Total annual cost estimate 6,277,000$Cost of option per ton SOxreduced36,400$BART cost calculations 110607.xls-Furnace scrubber cost summaryE N V I R O N

# A PPENDIX 

# E:

G REENHOUSE 

# G AS 

# E MISSION 

# C ALCULATIONS

### E-1 BART Determination Alcoa Intalco Works Ferndale, Washington Greenhouse Gas Emission Calculations

Greenhouse gases (GHGs) are gaseous compounds that are consider ed to act as heat trapping constituents of the atmosphere. Although there are many gases that may trap heat in the atmosphere, there are six GHGs recognized by inte rnational and domestic regulations on climate change: carbon dioxide (CO 2 

### ), nitrous oxide (N 2 

### O), methane, hydrofluorocarbons (HFCs), chlorinated fluorocarbons (CFCs), and sulfur hexa fluoride. More than 80% of the global warming potential results from CO 2 

### emissions.

The proposed sulfur dioxide (SO 2 

### ) control devices will contribute to the facility’s overall emissions of GHGs via three mechanisms: (1) as a byproduct of the reaction chemistry in the scrubbers, (2) as indirect emissions from the gene ration of electricity required to power the scrubbing systems, and (3) as direct emissions from vehicle travel for th e additional personnel that will be required at the facility to maintain and operate the scrubbing systems.

The estimate of carbon dioxide emissions resulting fr om the reaction of limes tone with the sulfur dioxide in the exhaust streams is based on the theoretical reaction chemistry, assuming no other byproducts resulting from incomple te reaction. Consistent with the BART analysis, we assumed that 95% of the incoming sulfur dioxide reacts w ith the limestone, and hence is removed from the exhaust stream. There are three r eactions taking place in the scrubber:

1) Dissolution of the limestone in the scrubbing water:

CaCO 3 

### + H 2 

### O Æ Ca +2 

### + HCO 3 - 

### + OH 

### 2) Dissolution of the sulfur di oxide in the scrubbing water:

SO 2 

### + H 2 

### O Æ 2H + 

### + SO 3 -2



### 3) Oxidation of the sulfite ions to sulfate ions (a nd hence, formation of gypsum or calcium sulfate):

Ca +2 

### + HCO 3 - 

### + OH - 

### + 2H + 

### + SO 3 -2 

### + 1⁄2 O 2 

### Æ CaSO 4 

### + CO 2 

### +2 H 2 

### O

Consistent with the chemical balan ce shown above, for every mole of SO 2 

### reacted, a mole of carbon dioxide is formed.

The inlet sulfur dioxide molar flowrate was es timated based on design parameters provided by Hatch Associates 1 

### . Assuming a minimum 95% sulfur dioxide control efficiency (that is, assuming that 95% of the sulfur dioxide reacts with the limestone), the mass of carbon dioxide evolved was calculated based on the reaction chemistry presented above.

1 Hatch Associates. 2007. Pre-Feasibility Report – SO 2 Scrubbing for the INTALCO Primary Aluminum Smelter

. November 5. Tables 3 and 6 (potline exhaust an d anode baking furnace exhaust, respectively).

### E-2 The implementation of the proposed scrubbing systems would also generate GHGs indirectly, as a result of consuming electricity. The generation of electricity at some off-site location would produce GHGs. The methodology described in the California Climate Action Registry General Reporting Protocol (CCARGRP) 2 

### , for estimating indirect emissions of GHGs from electricity use was followed. Based on design specifi cations provided by Hatch Associates 3 

### , the daily electricity usage of each scrubber (potline fumes scrubber and the anode bake furnace scrubber) were multiplied by a state-specific carbon dioxide emi ssion factor. The state-specific emission factor was found in the USEPA Emissions and Generation Resource Integrated Database for 2006 (eGrid2006) 4 

### for Washington state. To estimate the em issions of nitrous oxide and methane (two minor GHG components from combustion sources), the default emission f actors provided in the CCARGRP 5 

### were used. To convert the estimated nitr ous oxide and methane emissions to carbon dioxide equivalents, the CCARG RP provides an estimate of each compound’s global warming potential (GWP) 6 

### . For example, methane has a GWP of 21 times that of carbon dioxide; therefore, to convert the methane emission rate to carbon dioxide equivalents, we multiply the methane emission rate by its GWP.

The last potential source of GHGs resulting fr om the implementation of the proposed scrubbing systems is from vehicle travel to and from th e facility by additional pe rsonnel necessary for the operation and maintenance of the scrubbing systems. Based on facility estimates, the potline fumes scrubbing system would require nine additional em ployees per day on weekdays and six additional personnel per day on weekends. Similarly, the anode baking furnace scrubbing system would require six additional employees per day on wee kdays and 4.5 additional personnel equivalents per day on weekends. It was assumed that each pers on would drive a roundtri p distance of 20 miles per day. This is approximately the roundtrip distance between the facility and downtown Bellingham, Washington. The emission estimate s of carbon monoxide, nitrous oxide, and methane in the vehicle exhaust were based on assuming an average fuel economy. The fleet average (1988 to 2007) fuel economy from the USEPA 7 

### was used. The emission f actor for carbon dioxide was provided in the CCARGRP for non-California gasoline 8 

### . The emission factors for nitrous oxide and methane from vehicles were based on the average of the 1988 to present emission factors provided in the CCARGRP 9 

### . To convert the nitrous oxide a nd methane emission rates to carbon dioxide equivalents, the GWP for each co mpound was applied as discussed above.

2 California Climate Action Registry. 2007. California Climate Action Registry General Reporting Protocol (CCARGRP): Reporting Entity-Wide Greenhouse Gas Emissions . Version 2.2. March. Chapter 6.

3 Hatch Associates. 2007. Pre-Feasibility Report – SO 2 Scrubbing for the INTALCO Primary Aluminum Smelter

. November 5. Tables 5 and 8 (po tline fumes scrubbing and anode baking furnace scrubbing, respectively).

4 United States Environmental Protection Agency (USEPA). 2007. Emissions and Generation Resource Integrated Database for 2006 (eGrid2006). Version 2.1. April. Year 2004 summary tables.

5 California Climate Action Registry. 2007. California Climate Action Registry General Reporting Protocol (CCARGRP): Reporting Entity-Wide Greenhouse Gas Emissions . Version 2.2. March. Table C-2

6 Ibid. Table III.6-1.

7 United States Environmental Protection Agency (USEPA). 2007. Light-Duty Automotive Technology and Fuel Economy Trends: 1975 to 2007 (Table 1 – Cars and Trucks).

8 California Climate Action Registry. 2007. California Climate Action Registry General Reporting Protocol (CCARGRP): Reporting Entity-Wide Greenhouse Gas Emissions . Version 2.2. March. Table C-3.

9 Ibid. Table C-4 (used weighted average of the factors provided for various spans of model years).

### E-3 The GHG emission calculations descri bed above are presented in the attached tables. The total GHGs (in carbon dioxide equivalents) generated by the implementation of the proposed scrubbing system for the potline fumes was estimated to be 96,441 pounds per day, or 17,598 tons per year. The total GHGs (in carbon dioxide equivalents) ge nerated by the implementation of the proposed scrubbing system for the anode baking furnace was estimated to be 7,298 pounds per day, or 1,330 tons per year.Greenhouse Gases Emissions Intalco (Ferndale, WA)

Scope :

Assumptions :

Sources of Greenhouse Gases :

Summary of Potline Wet Scrubber GHG Emission Estimates :

Mass of CO 2 evolved from scrubbing potroom emissions 31,969 lb/day Mass of GHGs (in CO 2 equivalents) evolved from electricity production for scrubbing system 64,294 lb/day Mass of GHGs (in CO 2 equivalents) evolved from vehicle travel for additional personnel 177.9 lb/day 96,441 lb/day 17,597 tons/yr

Summary of Anode Bake Furnace Wet Scrubber GHG Emission Estimates :

Mass of CO 2 evolved from scrubbing anode bake furnace emissions 663 lb/day Mass of GHGs (in CO 2 equivalents) evolved from electricity production for scrubbing system 6,516 lb/day Mass of GHGs (in CO 2 equivalents) evolved from vehicle travel for additional personnel 118.6 lb/day 7,298 lb/day 1,330 tons/yr TOTAL GHGs (CO 2 equivalents)

TOTAL GHGs (CO 2 equivalents)

- The addition of personnel as a result of the operation of the scrubbing systems (vehicle travel) Calculation of greenhouse gases from the implementation of a flue gas desulfurization system. There will be one scrubbing system for the potrooms and one for the anode baking furnace. The scrubbing system consists of a limestone-gypsum forced oxidation (LSFO) process.

CO 2 is the primary greenhouse gas evolved. Other components, such as methane or nitrous oxide are in de minimus quantities. These will be included where there is sufficient information for their estimate.

- Reaction chemistry of the limestone and sulfur dioxide (LSFO) - Energy consumption of the scrubbing systemsGHG Emissions from Scrubbing Potline EmissionsScrubbing Reaction Chemistry:1) CaCO3+ H2O ------> Ca+2+ HCO3-+ OH2) SO2+ H2O -----------> 2H++ SO3-23) Ca+2+ HCO3-+ OH-+ SO3-2+ 2H++ 1/2 O2----------------> CaSO4+ CO2+ 2H2OSo, for every one mole of SO2(64 grams) removed, one mole of CO2(44 grams) is evolved.Based on the final Hatch pre-feasibility report (dated November 5, 2007):Parameter ReferenceSO2concentration300mg/Nm3Hatch, Table 3Flowrate 1,814,880 scfm Hatch, Table 351,394 m3/minSO2at inlet of FGD system257.0 grams/second Calculated, based on FGD inlet flow characteristics presented in Hatch, Table 34.02moles SO2/second Based on molar mass of SO2of 64 grams/moleRemoval efficiency 95% minimum Hatch, Table 4Moles of SO2reacted3.81moles SO2/secondMoles of CO2evolved3.81moles CO2/secondMass of CO2evolved167.8grams CO2/second Based on molar mass of CO2of 44 grams/mole14,500,691grams CO2/day31,969lb CO2/dayValueGHG Emissions from Scrubbing Anode Baking Furnace Emissions

Scrubbing Reaction Chemistry:

1) CaCO 3 + H 2 O ------> Ca +2 + HCO 3 - + OH -

2) SO 2 + H 2 O -----------> 2H + + SO 3 -2

3) Ca +2 + HCO 3 - + OH - + SO 3 -2 + 2H + + 1/2 O 2 ----------------> CaSO 4 + CO 2 + 2H 2 O

So, for every one mole of SO 2 (64 grams) removed, one mole of CO 2 (48 grams) is evolved.

Based on the final Hatch pre-feasibility report (dated November 5, 2007):

Parameter Reference
SO 2 at inlet of FGD system 5.33 grams/second Hatch, Table 6

0.083 moles SO 2 /second Based on molar mass of SO 2 of 64 grams/mole Removal efficiency 95% minimum Hatch, Table 7
Moles of SO 2 reacted 0.079 moles SO 2 /second
Moles of CO 2 evolved 0.079 moles CO 2 /second
Mass of CO 2 evolved 3.5 grams CO 2 /second Based on molar mass of CO 2 of 44 grams/mole 300,772 grams CO 2 /day

663 lb CO 2 /day ValueGHGs resulting from electricity generation associated with potline scrubber system1ParametersReferenceElectricity usage for potline wet scrubber 7,400 kWh/h Hatch, Table 5Electricity usage for potline wet scrubber 177,600 kWh/day Assumes continuous operation of wet scrubberN2O global warming potential (GWP) 310 Table III.6.1 - CCARGRPMethane GWP 21 Table III.6.1 - CCARGRPEmission FactorsReferenceCO2360 lb/MWh Emission factors for Washington state (eGrid 2006 Version 2.1, April 2007)CO20.36 lb/kWhN2O 0.004 lb/MWh Default emission factors for N2O and methane for Washington state (Table C.2, CCARGRP)Methane 0.037 lb/MWh Default emission factors for N2O and methane for Washington state (Table C.2, CCARGRP)Emission EstimatesCO263,936 lb/dayN2O 0.71 lb/dayMethane 6.57 lb/dayConversion of non-CO2GHGs to CO2equivalentsCO263,936 lb/dayN2O - CO2equivalents 220 lb/dayMethane - CO2equivalents 138 lb/dayTotal CO2equivalents 64,294 lb/dayNotes:1Based on methodology described in theCalifornia Climate Action Registry General Reporting Protocol (CCARGRP)(March 2007) and the data in the USEPAEmissions & Generation Resource Integrated Database(eGrid2006).GHGs resulting from electricity generation associated with anode bake furnace scrubber system1ParametersReferenceElectricity usage for anode bake furnace wet scrubber 750 kWh/h Hatch, Table 8Electricity usage for anode bake furnace wet scrubber 18,000 kWh/day Assumes continuous operation of wet scrubberN2O global warming potential (GWP) 310 Table III.6.1 - CCARGRPMethane GWP 21 Table III.6.1 - CCARGRPEmission FactorsReferenceCO2360 lb/MWh Emission factors for Washington state (eGrid 2006 Version 2.1, April 2007)CO20.36 lb/kWhN2O 0.004 lb/MWh Default emission factors for N2O and methane for Washington state (Table C.2, CCARGRP)Methane 0.037 lb/MWh Default emission factors for N2O and methane for Washington state (Table C.2, CCARGRP)Emission EstimatesCO26,480 lb/dayN2O 0.07 lb/dayMethane 0.67 lb/dayConversion of non-CO2GHGs to CO2equivalentsCO26,480 lb/dayN2O - CO2equivalents 22 lb/dayMethane - CO2equivalents 14 lb/dayTotal CO2equivalents 6,516 lb/dayNotes:1Based on methodology described in theCalifornia Climate Action Registry General Reporting Protocol (CCARGRP)(March 2007) and the data in the USEPAEmissions & Generation Resource Integrated Database(eGrid2006).GHGs resulting from vehicle travel for additional personnel associated with potline scrubber system1ParametersReferenceAdditional operating personnel 3 One additional full-time operator per shift, three shifts per day (assumption)Additional maintenance personnel (weekdays) 6 Four additional full-time maintenance personnel, one shift per day, plus one additional fulltime maintenancepersonnel for off-shifts(assumption)Additional maintenance personnel (weekends) 3 One additional full-time maintenance personnel for off-shifts (assumption)Total additional personnel (weekdays) 9Total additional personnel (weekends) 6Daily round trip distance 20 miles/trip Assumption (distance from plant to downtown Bellingham, WA is approximately 10 miles)Total daily mileage (weekdays) 180 miles/dayTotal daily mileage (weekends) 120 miles/dayAverage fuel economy 20.3 miles/gallon Fleet average (1988 to 2007 model years); USEPA, Light-Duty Automotive Technologyand Fuel EconomyTrends: 1975 to 2007, Table 1(Cars and Trucks)N2O global warming potential (GWP) 310 Table III.6.1 - CCARGRPMethane GWP 21 Table III.6.1 - CCARGRPEmission FactorsReferenceCO2emission factor 8.78 kg/gallon Non-CA gasoline; Table C.3, CCARGRPN2O emission factor 0.050 grams/mile Weighted average of 1988 to present automobile model years; Table C.4, CCARGRPMethane emission factor 0.049 grams/mile Weighted average of 1988 to present automobile model years; Table C.4, CCARGRPEmission EstimatesCO2(weekdays) 171.4 lb/dayN2O (weekdays) 0.020 lb/dayMethane (weekdays) 0.019 lb/dayCO2(weekends) 114.3 lb/dayN2O (weekends) 0.013 lb/dayMethane (weekends) 0.013 lb/dayConversion of non-CO2GHGs to CO2equivalentsCO2(weekdays) 171.4 lb/dayN2O - CO2equivalents (weekdays) 6.2 lb/dayMethane - CO2equivalents (weekdays) 0.4 lb/dayTotal CO2equivalents (weekdays) 177.9 lb/dayCO2(weekends) 114.3 lb/dayN2O - CO2equivalents (weekends) 4.1 lb/dayMethane - CO2equivalents (weekends) 0.3 lb/dayTotal CO2equivalents (weekends) 118.6 lb/dayCO2(annual) 28.2 tons/yrN2O - CO2equivalents (annual) 1.0 tons/yrMethane - CO2equivalents (annual) 0.1 tons/yrTotal CO2equivalents (annual) 29.3 tons/yrNotes:1Based on methodology described in theCalifornia Climate Action Registry General Reporting Protocol (CCARGRP)(March 2007).GHGs resulting from vehicle travel for additional personnel associated with anode bake furnace scrubber system1ParametersReferenceAdditional operating personnel 3 One additional full-time operator per shift, three shifts per day (assumption)Additional maintenance personnel (weekdays) 3 Two additional full-time maintenance personnel, one shift per day, plus one additional halftime equivalent maintenancepersonnel for off-shifts(assumption)Additional maintenance personnel (weekends) 1.5 One additional half-time equivalent maintenance personnel for off-shifts (assumption)Total additional personnel (weekdays) 6Total additional personnel (weekends) 4.5Daily round trip distance 20 miles/trip Assumption (distance from plant to downtown Bellingham, WA is approximately 10 miles)Total daily mileage (weekdays) 120 miles/dayTotal daily mileage (weekends) 90 miles/dayAverage fuel economy 20.3 miles/gallon Fleet average (1988 to 2007 model years); USEPA, Light-Duty Automotive Technologyand Fuel EconomyTrends: 1975 to 2007, Table 1(Cars and Trucks)N2O global warming potential (GWP) 310 Table III.6.1 - CCARGRPMethane GWP 21 Table III.6.1 - CCARGRPEmission FactorsReferenceCO2emission factor 8.78 kg/gallon Non-CA gasoline; Table C.3, CCARGRPN2O emission factor 0.050 grams/mile Weighted average of 1988 to present automobile model years; Table C.4, CCARGRPMethane emission factor 0.049 grams/mile Weighted average of 1988 to present automobile model years; Table C.4, CCARGRPEmission EstimatesCO2(weekdays) 114.3 lb/dayN2O (weekdays) 0.013 lb/dayMethane (weekdays) 0.013 lb/dayCO2(weekends) 85.7 lb/dayN2O (weekends) 0.0099 lb/dayMethane (weekends) 0.0096 lb/dayConversion of non-CO2GHGs to CO2equivalentsCO2(weekdays) 114.3 lb/dayN2O - CO2equivalents (weekdays) 4.1 lb/dayMethane - CO2equivalents (weekdays) 0.3 lb/dayTotal CO2equivalents (weekdays) 118.6 lb/dayCO2(weekends) 85.7 lb/dayN2O - CO2equivalents (weekends) 3.1 lb/dayMethane - CO2equivalents (weekends) 0.2 lb/dayTotal CO2equivalents (weekends) 89.0 lb/dayCO2(annual) 19.3 tons/yrN2O - CO2equivalents (annual) 0.7 tons/yrMethane - CO2equivalents (annual) 0.05 tons/yrTotal CO2equivalents (annual) 20.0 tons/yrNotes:1Based on methodology described in theCalifornia Climate Action Registry General Reporting Protocol (CCARGRP)(March 2007).