## RESULTS OF THE 2013 EMISSIONS TESTING

SECTION 114 – INFORMATION COLLECTION REQUEST (ICR)

Century Aluminum of Kentucky, LLC Hawesville, Kentucky

Submitted to:

Jamie Coomes Century Aluminum of Kentucky, LLC 1627 State Route 271 North Hawesville, Kentucky 42303

Prepared by: GEL Engineering, LLC Post Office Box 30712 Charleston, South Carolina 29417

May 29, 2013GEL Engineering, LLC

A Member of The GEL Group, Inc. Nsas00713 

### RESULTS OF THE 2013 EMISSIONS TESTING

SECTION 114 – INFORMATION COLLECTION REQUEST (ICR)

Century Aluminum of Kentucky, LLC Hawesville, Kentucky

Table of Contents

Section Subject Page Signature Page ...................................

................................................... ............ iii Executive Summary ................................

................................................... ........ iv 1.0 Introduction ..................................

................................................... ................. 1 2.0 Testing Event Participants ....................

................................................... ......... 1 3.0 Identification of Substance, Material or Produc t Sampled .............................. 2 3.1 Potline 1-4 EP84 (Stack) ....................

................................................... ... 2 3.2 Potline 4 EP88 (Roof Monitor) ................ ................................................. 2 4.0 Detailed Process Description ..................

................................................... ....... 3 5.0 Test Results ..................................

................................................... .................. 3 6.0 Identification of Method(s) Used ..............

................................................... .... 4
6.1 Stack Sampling Locations .....................

................................................... . 4 6.2 Velocity and Volumetric Flow Rates ........... ............................................. 4 6.3 Dry Molecular Weight .........................

................................................... .. 5
6.4 Moisture Content .............................

................................................... .... 5
6.5 Emissions Determinations .....................

.................................................. 5 6.5.1 Particulate Matter Emissions Determination .............................. 5 6.5.2 Metals Emissions Determination................................. .................. 5
6.5.3 POM Emissions Determinations ............. ..................................... 6 7.0 Date of Performance Test ......................

................................................... ........ 6 8.0 Test Plan and Procedures ......................

................................................... ........ 6 9.0 Identification of Substance, Material or Produc t Sampled .............................. 6 10.0 Deviations/Additions/Exclusions – Test Plan/ Test Methods/Quality Manual ......................

................................................... 6 11.0 Specific Test Conditions/Environmental Conditi ons ........................................ 6 12.0 Test Results: Uncertainty/Errors/Limiting Cond itions ..................................... 6ii

GEL Engineering, LLC A Member of The GEL Group, Inc. nsas00713 

### RESULTS OF THE 2013 EMISSIONS TESTING

SECTION 114 – INFORMATION COLLECTION REQUEST (ICR)

Century Aluminum of Kentucky, LLC Hawesville, Kentucky

Table of Contents (Cont.) Section Subject Page

13.0 Equipment Calibration Certificates ...........

................................................... .... 6

13.1 Nozzles .....................................

................................................... ............. 7 13.2 Pitot Tubes .................................

................................................... ........... 7 13.3 Dry Gas Meter ...............................

................................................... ........ 7 13.4 Thermocouples ...............................

................................................... ...... 7 13.5 Balance .....................................

................................................... ............. 7
13.6 Barometer ...................................

................................................... .......... 7 14.0 Documentation and Sufficient Raw Data to Verify and Reproduce Report Calculations ......... ............................................. 7

Appendices I ERT Reports II Summary of Test Results
III Test Method Formulas and Nomenclature
IV Field Data Sheets V Laboratory Analytical Data VI Method 315 Analytical Report VII Method 29 Analytical Report VIII Facility and Process Data IX Equipment Calibration Data X Anemometer Readingsiii

GEL Engineering, LLC A Member of The GEL Group, Inc. nsas00713 Signature Page

This document entitled, “Results of the 2013 Emissi ons Testing Section 114 – Information Collection Request (ICR),” has been prepared and re viewed by the undersigned at the request of and for the exclusive use of Century Aluminum of Ke ntucky, LLC facility located in Hawesville, Kentucky. It has been prepared in accordance with accepted quality control practices and it has been reviewed by the undersigned.

Craig McKenzie, QSTI Senior Project Manager

Kirk Alexander Senior Project Manager

Keith McCullock Industrial Services Business Unit Manager

May 29, 2013

Dateiv

GEL Engineering, LLC A Member of The GEL Group, Inc. nsas00713 Executive Summary Emission testing of the Potline 4 Main Stack and M1 4 Roof Monitor Downcomer located at the Century Aluminum of Kentucky, LLC facility in Hawes ville, Kentucky, was performed by GEL Engineering, LLC (GEL) personnel on March 12-14, 20 13 and May 7-9, 2013. The following table provides the measured emission rates:

EMISSIONS TEST RESULTS (Test Run Averages)

.

Pollutant EPA Method Line 1-4 Stack (lbs/hr) Line 1-4 Stack

(lbs/ton processed) 1 Line 4

Roof Monitor 2 (lbs/hr) Downcomer 2

(lbs/ton processed)

PM 17 NA NA 33.22 5.29

POM 315 4.09 0.163 8.04 1.15
Antimony 29 1.45E-03 5.78E-05 8.28E-04 1.19E-04

Arsenic 29 4.87E-03 1.94E-04 1.56E-03 2.23E-04
Beryllium 29 7.11E-03 2.84E-04 2.14E-03 3.06E-04

Cadmium 29 1.60E-03 6.38E-05 6.54E-04 9.36E-05

Chromium 29 1.15E-02 4.58E-04 1.62E-02 2.31E-03

Cobalt 29 1.56E-03 6.22E-05 3.66E-03 5.24E-04

Lead 29 2.41E-02 9.63E-04 1.05E-02 1.51E-03
Manganese 29 1.34E-02 5.33E-04 5.27E-02 7.53E-03

Nickel 29 4.90E-02 1.96E-03 1.65E-01 2.36E-02
Mercury 29 6.85E-04 2.74E-05 < 1.23E-03 < 1.76E-04

Selenium 29 1.18E-03 4.72E-05 6.55E-04 9.37E-05

1 Note: lbs/ton processed = pounds per ton of aluminu m processed. 2 Note: The mass emissions are based upon the air fl ow rates taken from the two plant anemometers during testing. The Potline 4 M14 Dow ncomer total line consists of two rooms. The anemometer readings are provided in Appendix VII.GEL Engineering, LLC

A Member of The GEL Group, Inc. Nsas00713 

### RESULTS OF THE 2013 EMISSIONS TESTING

SECTION 114 – INFORMATION COLLECTION REQUEST

Century Aluminum of Kentucky, LLC Hawesville, Kentucky

1.0 INTRODUCTION Stationary source sampling of Potline 4 located at the Century Aluminum of Kentucky, LLC (Century Aluminum) facility in Hawesville, Kentucky was performed by GEL Engineering, LLC (GEL) personnel on March 12-14, 2013 and May 7-9, 2 013. This sampling program entailed sampling at two sampling locations;

• Potline 4 Air Control Stack (Main Stack) – EP84

• Potline 4 M14 Roof Monitor Manifold Stack (Downcome r) – EP88 The purpose of this stack testing event was to adhe re to an Information Collection Request (ICR), issued by the United States Environmental Pr otection Agency (USEPA) specifically pursuant to Clean Air Act (CAA) Section 114 Emissions Data Coll ection Request for the Primary Aluminum Reduction Plant Source Category.

2.0 TESTING EVENT PARTICIPANTS The following table summarizes the participants in the testing event:

Name Job Title Affiliation Craig McKenzie, QSTI Senior Project Manager GEL Kirk Alexander, QSTI Senior Project Manager GEL Gregg Szymkowicz Field Team Leader GEL
Charles Rice Sampling Technician GEL
Sean Huber Sampling Technician GEL
Derek Anderson Sampling Technician GEL
Jamie Coomes Environmental Operations Century
Mr. Craig McKenzie of GEL served as Project Manager , and the client representative for the stationary source sampling was Mr. Jamie Coomes. M r. Craig McKenzie was the Qualified Source Testing Individual (QSTI) on site during thi s testing event.

3.0 IDENTIFICATION OF SUBSTANCE, MATERIAL OR PRODUC T SAMPLED Pursuant to the guidelines of the ICR notification, Century Aluminum submitted past testing data on targeted sources to the EPA on March 22, 20 13. Upon review, the USEPA outlined specific sources and parameters to be tested. The specific sources targeted for this ICR andResults of the 2013 Emissions Testing of Line 4 May 29, 2013

Main Stack and Downcomer Page 2 Century Aluminum of Kentucky, LLC, Hawesville, Kent ucky

GEL Engineering, LLC A Member of The GEL Group, Inc. Nsas00713 parameters are as follows:
3.1 Potline 1-4 Stack (EP84)
Emissions tests were conducted on the exhaust stack using the EPA methodologies listed
below:

Parameter Method(s) Duration Gas Velocity and Volume Flow Rates 1 & 2 as required

O 2 /CO 2 3 as required

Moisture Content 4 as required

Metals 1 29 3 four-hour runs

Polycyclic Organic Matter (POM) 315 6 three-hour

runs

**Notes:

1 Metals targeted included antimony, arsenic, berylli um, cadmium, chromium, cobalt, lead, manganese, nickel, selenium and mercury.

3.2 Potline 4 Roof Monitor (EP88)
Emissions tests were conducted on the Line 4 perman ently installed manifold system, using the EPA methodologies listed below:

Parameter Method(s) Duration Gas Velocity and Volume Flow Rates 14 as required

O 2 /CO 2 3 as required

Moisture Content 4 as required

PM 17 6 four-hour runs

Metals 1 29 3 four-hour runs

POM 315 6 three-hour

runs

**Notes:

1 Metals targeted included antimony, arsenic, berylli um, cadmium, chromium, cobalt, lead, manganese, nickel, selenium and mercury. Please note all emissions testing were conducted on the Line 4 manifold during the night shifts. This was done to perform the testing durin g the anode changes as detailed by the ICR notification. During each test run, multiple a nodes were set along Line 4. A process log of the anode setting is included in Appendix VIII.Results of the 2013 Emissions Testing of Line 4 May 29, 2013

Main Stack and Downcomer Page 3 Century Aluminum of Kentucky, LLC, Hawesville, Kent ucky

GEL Engineering, LLC A Member of The GEL Group, Inc. Nsas00713 Line 4 consists of two buildings, with each buildin g containing two sections. The ICR testing of the Line 4 Roof Manifold followed the guidelines of EPA Method 14. The Summary of Results for the Downcomer sampling is detailed in t he EPA Electronic Reporting Tool (ERT). Whereas, the Summary of Test Results for the Testin g Section of Line 4 and entire line emissions factors are detailed in Appendix II.

4.0 DETAILED PROCESS DESCRIPTION

Century’s Kentucky facility is located in Hancock C ounty near Hawesville. Century is a primary aluminum reduction facility th at produces aluminum by the electrolytic reduction of aluminum oxide (alumina). Alumina arrives at the plant via barge or rail transport for reduction to aluminum i n shallow rectangular cells called “pots.” These pots are carbon steel shells and are arranged electrically in series to form a potline. The building that houses the potli ne is divided into two rooms by a center aisle. Each section of the line is called a potroom and each potroom has a dedicated roof monitor.

To facilitate the electrolytic reduction of alumina to aluminum, prebaked carbon blocks or anodes are suspended and extended into th e pot. These anodes serve as the means of introducing the electrical current to the pot. The lined shell acts as the cathode to complete the circuit. The pots cont ain alumina and cryolite that acts as the catalyst for the reaction. Other materials are also added to assist in the reaction. Molten aluminum is tapped from the pots and transferred to the casthouse for further processing. Emissions from t he process are captured by the shields that cover the pots and are transported to the emission control system for treatment. Fugitive emissions that escape from the pots when alumina is added or when anodes are replaced exhaust to the atmosphere through the roof monitors.

Potlines One through Four commenced operation in 19 69 and are considered Center-Worked Prebake 3 (CWPB 3) potlines subject t o a NESHAP emissions limit for Total Fluoride of 2.5 lbs per ton of aluminum produ ced.

5.0 TEST RESULTS Tests runs measuring the target parameters detailed in Sections 3.1 through 3.2 of this report were performed on March 12-14, 2013 and May 7-9, 2013. The test results obtained for this sampling program are summarized i n the Executive Summary. As per the guidance provided in the EPA’s ICR notification, al l emissions data from Methods 17, 29, and 315 were entered into the EPA ERT and submitted as per the ICR guidance. Also, the summary of the Line 4 Roof Monitor Method 14 calcul ations, which are not supported by the ERT, are detailed in the Summary of Test Result s. All emissions testing followed the directives cited in Tables 1.1 and 1.2 of the ICR n otification in regards to sources targeted, minimum sample volume collected, and units of measu rements (pounds per hour and pounds per ton aluminum produced). The ERT reports for each source are included in Appendix I. The Summary of Test Results for the Me thod 14 testing is included in AppendixResults of the 2013 Emissions Testing of Line 4 May 29, 2013

Main Stack and Downcomer Page 4 Century Aluminum of Kentucky, LLC, Hawesville, Kent ucky

GEL Engineering, LLC A Member of The GEL Group, Inc. Nsas00713 II.

6.0 IDENTIFICATION OF METHOD(S) USED Test parameters and sampling methods for the test p rogram are summarized in Table 1. Sampling methods and analytical procedures recommen ded by the EPA were used during this test program. Laboratory and calibration proc edures described in EPA Quality Assurance Handbook for Air Pollution Control System s, Vol. III, (EPA/600/R-94/038c), and the QA/QC procedures specified in EPA Reference Met hods 1, 2, 3, 4, 14, 17, 29, and 315 were followed during execution of the test program. The sampling and analytical methodologies are described below.

6.1 Stack Sampling Locations EPA Method 1 was used to determine the number and l ocation of the sampling points for flow determination for both the Main and Downcomer Stacks. The test points for the both sources are presented in Appendix IV. The Main Sta ck is a 311.75-inch diameter stack and the sampling platform is located approximately 300 feet above the base of the stack. As specified by Method 1, a horizontal cross section o f each stack was divided 12 equal areas with 3 traverse points located on each of four perp endicular diameters.

The Downcomer stack is a 14-inch diameter stack. A s specified by Method 1, a horizontal cross section of each stack was divided 12 equal ar eas with 6 traverse points located on each of two perpendicular diameters. Potline 4 con sists of two buildings, each with two rooms. Each section of the Potline 4 measures 459 feet and 5 inches in length and 19 feet and 4 inches in width. The Potline 4 Roof Monitor follows the guidelines of EPA Method 14, with relation to eight manifold nozzles per sec tion and two anemometers position along the testing section. The Downcomer sampling location is located in a building along Line 4.

6.2 Velocity and Volumetric Flow Rates EPA Method 2 was used to determine the stack gas ve locity and volumetric flow rates for the Main Stack. Velocity and volumetric flow rates were calculated based on the average of the measurements for each test run. The temperatur e of the stack was measured by a calibrated Type K Thermocouple positioned in the st ack in accordance with EPA Method 2. EPA Method 14 was used to determine the stack gas v elocity and volumetric flow rates for the Downcomer Stack. Velocity and volumetric flow rates were calculated based on the average of velocity traverses performed before and after each test run. Concurrent readings from two plant anemometers were also recor ded during each test run. The anemometers are continuously recording the flows. These readings were averaged and used to determine the Roof Monitor exhaust rate for one section. Since an entire line consists of two rooms, the exhaust rate for the ent ire line is by multiplying the emissions results by 4 to calculate pounds per hour. All gui delines were followed as per Method 14 for calculations and isokinetic verifications.Results of the 2013 Emissions Testing of Line 4 May 29, 2013

Main Stack and Downcomer Page 5 Century Aluminum of Kentucky, LLC, Hawesville, Kent ucky

GEL Engineering, LLC A Member of The GEL Group, Inc. Nsas00713 6.3 Dry Molecular Weight In accordance with the guidelines in EPA Method 2, the dry molecular weight was assumed to be that of ambient air or 29.0.

6.4 Moisture Content EPA Method 4 was used to determine the moisture con tent of the stack gas. Following the protocol given in Method 4, the volume of the conde nsed water vapor collected in the impingers and the silica gel were weighed before an d after sample collection. The difference in the two weights of the silica gel, th e difference in the two weights of condensed water vapor captured in the impingers, an d the volume of air sampled with the impingers train were used to calculate the moisture content of the stack gas.

6.5 Emissions Determinations Sampling methods and analytical procedures recommen ded by the EPA were used during this test program. The sampling and analyti cal methodologies are described below.

6.5.1 PM Emissions Determination A total of six, 4-hour test runs using EPA Method 1 7 to determine the PM emission rate were conducted on the Line 4 Roof Monitor May 7-9, 2013. Particulate emissions were collected isokinetically through a stainless steel sampling head which contained a stainless steel filter holder with a quartz fiber filter. Th e gas then traveled through a heated probe to the impinger train.

Upon completion of each sampling run, the sampling head was removed from the probe and allowed to cool prior to sample recovery. Samp le recovery consisted of acetone rinses of the nozzle and filter head prior to the filter. The quartz fiber filter was also recovered at the end of each sampling run for PM determination. The Method 17 weight sheets are included in Appendix V.

6.5.2 Metals Emissions Determinations Three 4-hour test runs were conducted using EPA Met hod 29 to determine the emission rates for the target metals at the Line 1-4 Stack a nd Line 4 Roof Monitor. Emissions were collected isokinetically through a heated sampling probe onto heated high purity quartz fiber filters. The sampling train was equipped wit h a glass nozzle, a glass probe liner, a quartz fiber filter, two impingers charged with nit ric acid and hydrogen peroxide solution (5% HNO 3 /10% H 2 O 2 ), an empty impinger, two impingers charged with po tassium permanganate/sulfuric acid solution (4% KMnO 4 /10% H 2 SO 4 ) and an impinger charged with silica gel. The sample train nozzle and probe were rinsed and scrubbed with acetone until clean in the field. The cyclone bypass and front h alf of the filter housing were rinsed and scrubbed with acetone until clean upon return to th e laboratory. The acetone rinse from each run was collected and analyzed with the collec ted filters to determine PM emissions. The sample train components, including the nozzle, probe, and filter housing, were rinsedResults of the 2013 Emissions Testing of Line 4 May 29, 2013

Main Stack and Downcomer Page 6 Century Aluminum of Kentucky, LLC, Hawesville, Kent ucky

GEL Engineering, LLC A Member of The GEL Group, Inc. Nsas00713 and scrubbed with the appropriate rinse solutions u ntil clean for metals analysis. The impinger solutions, the rinse solutions, and the fi lters collected from each run and a field blank was then submitted to Element One, Inc. (Elem ent One), digested, and analyzed to determine metals emissions. Recovery of moisture t rain and probe rinses were performed in the field while filter recovery and filter bell rinses were performed at GEL.

6.5.3 Polycyclic Organic Matter Emissions Determina tions A total of three, 3-hour test runs on Line 1-4 Stac k and six, 3-hour runs for the Line 4 Roof Monitor using EPA Method 315 to determine the POM e mission rates were conducted. The sampling train was equipped with a Pyrex nozzle and probe liner, a high purity quartz filter, one Greenburg-Smith impinger and one standa rd impinger both charged with deionized water, one empty standard impinger, and o ne impinger charged with silica gel. POM emissions were collected isokinetically through the nozzle and probe onto the heated filter. The sample train components, including the nozzle, probe, and filter housing, were rinsed and scrubbed until clean after each test run as per EPA Method 315. The samples were marked, labeled, and shipped to Resolution Ana lytics for analysis.

7.0 DATE OF PERFORMANCE TEST The performance test was conducted on March 12-14, 2013 and May 7-9, 2013.

8.0 TEST PLAN AND PROCEDURES A test plan was submitted to DEP by Century Aluminu m for this performance test. Refer to Table 1 for a summary of the test parameters and sa mpling methods for the test program.

9.0 IDENTIFICATION OF SUBSTANCE, MATERIAL OR PRODUC T SAMPLED Emission testing of the exhaust flue gas of Line 4 main exhaust stack was performed for Metals and POM. The Line 4 Downcomer was also test ed for PM, metals, and POM.

10.0 DEVIATIONS/ADDITIONS/EXCLUSIONS – TEST PLAN/TE ST METHODS/QUALITY MANUAL A test plan was required for this performance test. The performance test was executed without any deviations, additions or exclusions to the test methods detailed in the test plan and GEL’s quality manual.

11.0 SPECIFIC TEST CONDITIONS/ENVIRONMENTAL CONDITI ONS The Line 4 process was operating under normal condi tions.

12.0 TEST RESULTS: UNCERTAINTY/ERRORS/LIMITING COND ITIONS The performance test was performed as per the test methods. There were no limiting conditions or errors during the execution of this t esting event.

13.0 EQUIPMENT CALIBRATION CERTIFICATES Equipment calibration data is included in Appendix IX.Results of the 2013 Emissions Testing of Line 4 May 29, 2013

Main Stack and Downcomer Page 7 Century Aluminum of Kentucky, LLC, Hawesville, Kent ucky

GEL Engineering, LLC A Member of The GEL Group, Inc. Nsas00713 13.1 Nozzles Each nozzle is purchased from a stack testing equip ment supplier and inspected and calibrated before putting it into field use. There after, it is inspected prior to use and if damaged, the nozzle is not used. A set of three me asurements is made prior to use and must be within 0.002 inches. Nozzles are checked p rior and after each source test.

13.2 Pitot Tubes All pitot tubes used by GEL are purchased along wit h the probe assembly from a stack testing equipment supplier. Prior to being used, t he pitot tubes are calibrated as per Method 2. Pitot tubes are inspected before each so urce test and receive a complete calibration once per year.

13.3 Dry Gas Meter Complete dry gas meter calibrations are performed a nnually. After a source test, a single point calibration is conducted at the average orifi ce meter (DH) and maximum vacuum readings encountered during the test. If the dry g as meter calibration factor differs from the annual calibration by more than +/- 0.05, it is repaired and given another annual calibration.

13.4 Thermocouples Each new thermocouple purchased by GEL is checked a nd calibrated prior to use. After each source test, all temperature-sensing devices u sed receive a one-point calibration check as per Method 2.

13.5 Balance GEL technicians utilize an Ohaus Model E12140 Seria l No. G2391121320091P balance. The serial number for the calibration weight set is 39325. A copy of the calibration log will be provided upon request.

13.6 Barometer GEL utilizes the National Weather Service to determ ine the current barometric pressure. This is obtained either by telephone or using the I nternet.

14.0 DOCUMENTATION AND SUFFICIENT RAW DATA TO VERIF Y AND REPRODUCE REPORT CALCULATIONS Test method formulas and nomenclature are included in Appendix III. The field data sheets for this testing event are included in Appendix IV. The laboratory analytical data is included in Appendices V, IV, and VII. Facility process dat a is included in Appendix VIII.