MEMORANDUM 

DATE: September 10, 2015 

SUBJECT: Redline Version of Subpart LL showing the Differences 

from the Current Subpart LL and the 2015 Amended Rule 

TO: David Putney, U.S. Environmental Protection Agency 

From: David Green and Matt Hakos, RTI International 

The purpose of this memorandum is to present a redline version 

of subpart LL, Primary Aluminum Production Source Category 

NESHAP, that shows the changes that have been made in the 

current rule by the 2015 final amendments.
1 

Subpart LL—National Emission Standards for Hazardous Air 

Pollutants for Primary Aluminum Reduction Plants 

§ 63.840 Applicability. 

(a) Except as provided in paragraph (b) of this section, 

the requirements of this subpart apply to the owner or operator 

of each new or existing pitch storage tank and new or existing 

potline, paste production plant, or anode bake furnace 

associated with primary aluminum production and located at a 

major source as defined in §63.2. 

(b) The requirements of this subpart do not apply to any 

existing anode bake furnace that is not located on the same site 

as a primary aluminum reduction plant. The owner or operator 

shall comply with the State MACT determination established by 

the applicable regulatory authority. 

(c) An owner or operator of an affected facility (potroom 

group or anode bake furnace) under §60.190 of this chapter may 

elect to comply with either the requirements of §63.845 of this 

subpart or the requirements of subpart S of part 60 of this 

chapter. 

§ 63.841 Incorporation by reference. Removed and Reserved. 

(a) The following material is incorporated by reference in 

the corresponding sections noted. This incorporation by 

reference was approved by the Director of the Federal Register 
2 

on October 7, 1997, in accordance with 5 U.S.C. 552(a) and 1 CFR 

part 51. These materials are incorporated as they exist on the 

date of approval, and notice of any change in the materials will 

be published in theFederal Register.Revisions to “Industrial 

Ventilation: A Manual of Recommended Practice” (22nd ed.) are 

applicable only after publication of a document in the 

 Federal Register to amend subpart LL to require use of the new 

information. 

(1) Chapter 3, “Local Exhaust Hoods” and Chapter 5, 

“Exhaust System Design Procedure” of “Industrial Ventilation: A 

Manual of Recommended Practice,” American Conference of 

Governmental Industrial Hygienists, 22nd edition, 1995, IBR 

approved for §§63.843(b) and 63.844(b); and 

(2) ASTM D 2986–95A, Standard Practice for Evaluation of 

Air Assay Media by the Monodisperse DOP (Dioctyl Phthalate) 

Smoke Test, IBR approved for section 7.1.1 of Method 315 in 

appendix A to this part. 

(b) The materials incorporated by reference are available 

for at the National Archives and Records Administration (NARA), 

and at the Air and Radiation Docket Center, U.S. EPA, 1200 

Pennsylvania Ave., NW., Washington, DC. For information on the 

availability of this material at NARA, call 202–741–6030, or go 

to: 

http://www.archives.gov/federal_register/code_of_federal_regulat
3 

ions/ibr_locations.html. The materials also are available for 

purchase from one of the following addresses: 

(1) Customer Service Department, American Conference of 

Governmental Industrial Hygienists (ACGIH), 1330 Kemper Meadow 

Drive, Cincinnati, Ohio 45240, telephone number (513) 742–2020; 

or 

(2) American Society for Testing and Materials, 100 Bar 

Harbour Drive, West Conshohocken, Pennsylvania 19428, telephone 

number (610) 832–9500.

§ 63.842 Definitions. 

Terms used in this subpart are defined in the Clean Air Act 

as amended (the Act), in §63.2, or in this section as follows: 

Anode bake cycle means the period during which the 

regularly repeated sequence of loading, preheating, firing, 

cooling, and removing anodes from all sections within an anode 

bake furnace occurs one time. 

Anode bake furnace means an oven in which the formed green 

anodes are baked for use in a prebake process. This definition 

includes multiple anode bake furnaces controlled by a common 

control device (bake furnaces controlled by a common control 

device are considered to be one source). 

Center-worked prebake (CWPB) process means a method of 

primary aluminum reduction using the prebake process in which 

the alumina feed is added down the center of the reduction cell. 
4 

Center-worked prebake one (CWPB1) means all existing 

center-worked prebake potlines not defined as center-worked 

prebake two (CWPB2) or center-worked prebake three (CWPB3) 

potlines. 

Center-worked prebake two (CWPB2) means all existing 

center-worked prebake potlines located at Alcoa in Rockdale, 

Texas; Kaiser Aluminum in Mead, Washington; Ormet Corporation in 

Hannibal, Ohio; Ravenswood Aluminum in Ravenswood, West 

Virginia; Reynolds Metals in Troutdale, Oregon; and Vanalco 

Aluminum in Vancouver, Washington. 

Center-worked prebake three (CWPB3) means all existing 

center-worked prebake potlines that produce very high purity 

aluminum, have a wet scrubber for the primary control system, 

and are located at the NSA primary aluminum plant in Hawesville, 

Kentucky. 

Continuous parameter monitoring system means the total 

equipment that may be required to meet the data acquisition and 

availability requirements of this subpart, used to sample, 

condition (if applicable), analyze, and provide a record of 

process or control system parameters. 

Horizontal stud Soderberg (HSS) process means a method of 

primary aluminum reduction using the Soderberg process in which 

the electrical current is introduced to the anode by steel rods 

(studs) inserted into the side of a monolithic anode. 
5 

High purity aluminum means aluminum produced with an 

average purity level of at least 99.9 percent.

Modified potroom group means an existing potroom group to 

which any physical change in, or change in the method of 

operation of, results in an increase in the amount of total 

fluoride emitted into the atmosphere by that potroom group.

Operating day means a 24-hour period between 12 midnight 

and the following midnight during which an affected source 

operates at any time. It is not necessary for operations to 

occur for the entire 24-hour period. 

Particulate matter (PM) means, for the purposes of this 

subpart, emissions of particulate matter that serve as a measure 

of total particulate emissions and as a surrogate for metal 

hazardous air pollutants contained in the particulates, 

including but not limited to: antimony, arsenic, beryllium, 

cadmium, chromium, cobalt, lead, manganese, nickel and selenium.

Paste production plant means the processes whereby calcined 

petroleum coke, coal tar pitch (hard or liquid), and/or other 

materials are mixed, transferred, and formed into briquettes or 

paste for vertical stud Soderberg (VSS) and HSS processes or 

into green anodes for a prebake process. This definition 

includes all operations from initial mixing to final forming 

(i.e., briquettes, paste, green anodes) within the paste plant, 

including conveyors and units managing heated liquid pitch. 
6 

Pitch storage tank means any fixed roof tank that is used 

to store liquid pitch that is not part of the paste production 

plant.

Polychlorinated biphenyl (PCB) means any or all of the 209 

possible chlorinated biphenyl isomers.

Polycyclic organic matter (POM) means organic matter 

extractable by methylene chloride as determined by Method 315 in 

appendix A to this part or by an approved alternative method. 

Potline means a single, discrete group of electrolytic 

reduction cells electrically connected in series, in which 

alumina is reduced to form aluminum. 

Potroom means a building unit that houses a group of 

electrolytic cells in which aluminum is produced. 

Potroom group means an uncontrolled potroom, a potroom that 

is controlled individually, or a group of potrooms or potroom 

segments ducted to a common control system. 

Prebake process means a method of primary aluminum 

reduction that uses an anode that was baked in an anode bake 

furnace, which is introduced into the top of the reduction cell 

and consumed as part of the reduction process. 

Primary aluminum reduction plant means any facility 

manufacturing aluminum by electrolytic reduction. 

Primary control system means the equipment used to capture 

the gases and particulate matter evacuated directly from the 
7 

reduction cell and the emission control device(s) used to remove 

pollutants prior to discharge of the cleaned gas to the 

atmosphere. A roof scrubber is not part of the primary control 

system. 

Primary emissions means the emissions discharged from the 

primary control system. 

Reconstructed potroom group means an existing potroom group 

for which the components are replaced to such an extent that the 

fixed capital cost of the new components exceeds 50 percent of 

the fixed capital cost that would be required to construct a 

comparable entirely new potroom group, and for which it is 

technologically and economically feasible to meet the applicable 

emission limits for total fluoride set forth in this subpart. 

Reconstruction means the replacement of components of a 

source to such an extent that: 

(1) All of the major components of the source are replaced 

(for example, the major components of a potline include the raw 

material handling system, reduction cells, superstructure, 

hooding, ductwork, etc.); and 

(2) It is technologically and economically feasible for the 

reconstructed source to meet the standards for new sources 

established in this subpart. 
8 

Roof monitor means that portion of the roof of a potroom 

building where gases not captured at the cell exit from the 

potroom. 

Secondary emissions means the fugitive emissions that are 

not captured and controlled by the primary control system and 

that escape through the roof monitor or through roof scrubbers. 

Side-worked prebake (SWPB) process means a method of 

primary aluminum reduction using the prebake process, in which 

the alumina is added along the sides of the reduction cell. 

Soderberg process means a method of primary aluminum 

reduction in which the anode paste mixture is baked in the 

reduction pot by the heat resulting from the electrolytic 

process.

Startup of an anode bake furnace means the process of 

initiating heating to the anode bake furnace. The startup or restart of the furnace begins when the heating begins. The startup 

or re-start concludes at the start of the second anode bake 

cycle if the furnace was at ambient temperature upon startup or 

when the anode bake cycle resumes if the furnace was not at 

ambient temperature.

Total fluorides (TF) means elemental fluorine and all 

fluoride compounds as measured by Methods 13A or 13B in appendix 

A to part 60 of this chapter or by an approved alternative 

method.
9 

Toxicity equivalence (TEQ) means an international method of 

expressing toxicity equivalents for PCBs as defined in U. S. 

EPA, Recommended Toxicity Equivalence Factors (TEFs) for Human 

Health Risk Assessments of 2,3,7,8-Tetrachlorodibenzo-p-dioxin 

and Dioxin-Like Compounds, EPA/100/R-10/005 December 2010.

Vertical stud Soderberg (VSS) process means a method of 

primary aluminum reduction using the Soderberg process, in which 

the electrical current is introduced to the anode by steel rods 

(studs) inserted into the top of a monolithic anode. 

Vertical stud Soderberg one (VSS1) means all existing 

vertical stud Soderberg potlines located either at Northwest 

Aluminum in The Dalles, Oregon, or at Goldendale Aluminum in 

Goldendale, Washington.

Vertical stud Soderberg two (VSS2) means all existing 

vertical stud Soderberg potlines located at Columbia Falls 

Aluminum in Columbia Falls, Montana. 

§ 63.843 Emission limits for existing sources. 

(a) Potlines. The owner or operator shall not discharge or 

cause to be discharged into the atmosphere any emissions of TF, 

or POM, PM, nickel, arsenic or PCB in excess of the applicable 

limits in paragraphs (a)(1) and (a)(2) through (a)(6) of this 

section. 

(1) TF limits. Emissions of TF shall not exceed: 
10 

(i) 0.95 kg/Mg (1.9 lb/ton) of aluminum produced for each 

CWPB1 potline; 

(ii) 1.5 kg/Mg (3.0 lb/ton) of aluminum produced for each 

CWPB2 potline; 

(iii) 1.25 kg/Mg (2.5 lb/ton) of aluminum produced for each 

CWPB3 potline; 

(iv) 0.8 kg/Mg (1.6 lb/ton) of aluminum produced for each 

SWPB potline; and

(v) 1.1 kg/Mg (2.2 lb/ton) of aluminum produced for each 

VSS1 potline;[Reserved]

(vi) 1.35 kg/Mg (2.7 lb/ton) of aluminum produced for each 

VSS2 potline.; and

(vii) 1.35 kg/Mg (2.7 lb/ton) of aluminum produced for each HSS 

potline.

(2) POM limits. Emissions of POM shall not exceed: 

(i) 2.35 kg/Mg (4.7 lb/ton) of aluminum produced for each 

HSS potline;[Reserved]

(ii) 1.2 kg/Mg (2.4 lb/ton) of aluminum produced for each 

VSS1 potline; and[Reserved]

(iii) 2.850.85 kg/Mg (5.71.9 lb/ton) of aluminum produced 

for each VSS2 potline;. 

(iv) 0.55 kg/Mg (1.1 lb/ton) of aluminum produced for each 

CWPB1 prebake potline; 
11 

(v) 6.0 kg/Mg (12 lb/ton) of aluminum produced for each 

CWPB2 prebake potline; 

(vi) 1.4 kg/Mg (2.7 lb/ton) of aluminum produced for each 

CWPB3 prebake potline; and 

(vii) 8.5 kg/Mg (17 lb/ton) of aluminum produced for each 

SWPB prebake potline. 

(3) PM limits. Emissions of PM shall not exceed: 

(i) 3.7 kg/Mg (7.4 lb/ton) of aluminum produced for each 

CWPB1 potline; 

(ii) 5.5 kg/Mg (11 lb/ton) of aluminum produced for each 

CWPB2 potline; 

(iii) 10 kg/Mg (20 lb/ton) of aluminum produced for each 

CWPB3 potline; 

(iv) 2.45 kg/Mg (4.9 lb/ton) of aluminum produced for each 

SWPB potline; and 

(v) 13 kg/Mg (26 lb/ton) of aluminum produced for each VSS2 

potline. 

(4) Nickel limit. Emissions of nickel shall not exceed 0.07 

lb/ton of aluminum produced from each VSS2 potline at a primary 

aluminum reduction plant.

(5) Arsenic limit. Emissions of arsenic shall not exceed 

0.006 lb/ton of aluminum produced from each VSS2 potline at a 

primary aluminum reduction plant. 
12 

(6) PCB limit. Emissions of PCB shall not exceed 2.0 μg 

toxicity equivalence (TEQ) per ton of aluminum produced from 

each VSS2 potline at a primary aluminum reduction plant.

(37) Change in subcategory. Any potline, other than a 

reconstructed potline, that is changed such that its applicable 

subcategory also changes shall meet the applicable emission 

limit in this subpart for the original subcategory or the new 

subcategory, whichever is more stringent. 

(b) Paste production plants. The owner or operator shall 

install, operate, and maintain equipment to capture and control 

POM and PM emissions from each paste production plant. 

(1) The emission capture system shall be installed and 

operated to meet the generally accepted engineering standards 

for minimum exhaust rates as published by the American 

Conference of Governmental Industrial Hygienists in Chapters 3 

and 5 of “Industrial Ventilation: A Handbook of Recommended 

Practice” (incorporated by reference; in §63.841 of this part 

see § 63.14); and 

(2) Captured emissions shall be routed through a closed 

system to a dry coke scrubber; or 

(3) The owner or operator may submit a written request for 

use of an alternative control device to the applicable 

regulatory authority for review and approval. The request shall 

contain information and data demonstrating that the alternative 
13 

control device achieves POM emissions less than 0.011 lb/ton of 

paste for plants with continuous mixers or POM emissions less 

than 0.024 lb/ton of paste for plants with batch mixers. The POM 

emission rate shall be determined by sampling using Method 315 

in appendix A to this part.

(4) PM limit. Emissions of PM shall not exceed 0.041 kg/Mg 

(0.082 lb/ton) of paste.

(c) Anode bake furnaces. The owner or operator shall not 

discharge or cause to be discharged into the atmosphere any 

emissions of TF, or POM, PM or mercury in excess of the limits 

in paragraphs (c)(1) and (c)(24) of this section. 

(1) TF limit. Emissions of TF shall not exceed 0.10 kg/Mg 

(0.20 lb/ton) of green anode; and

(2) POM limit. Emissions of POM shall not exceed 0.09 kg/Mg 

(0.18 lb/ton) of green anode.; 

(3) PM limit. Emissions of PM shall not exceed 0.10 kg/Mg 

(0.20 lb/ton) of green anode; and 

(4) Mercury limit. Emissions of mercury shall not exceed 

1.7 μg/dscm. 

(d) Pitch storage tanks. Each pitch storage tank shall be 

equipped with an emission control system designed and operated 

to reduce inlet emissions of POM by 95 percent or greater. 
14 

(e) COS limit. Emissions of COS must not exceed 1.95 kg/Mg 

(3.9 lb/ton) of aluminum produced for each potline. 

(f) At all times, the owner or operator must operate and 

maintain any affected source, including associated air pollution 

control equipment and monitoring equipment, in a manner 

consistent with safety and good air pollution control practices 

for minimizing emissions. Determination of whether such 

operation and maintenance procedures are being used will be 

based on information available to the Administrator which may 

include, but is not limited to, monitoring results, review of 

operation and maintenance procedures, review of operation and 

maintenance records and inspection of the source.

§ 63.844 Emission limits for new or reconstructed sources. 

(a) Potlines. The owner or operator shall not discharge or 

cause to be discharged into the atmosphere any emissions of TF, 

or POM, nickel, arsenic or PCB in excess of the limits in 

paragraphs (a)(1) and (a)(2)through (a)(6) of this section. 

(1) TF limit. Emissions of TF shall not exceed 0.6 kg/Mg 

(1.2 lb/ton) of aluminum produced; and 

(2) POM limit. Emissions of POM from Soderberg potlines 

shallmust not exceed 0.320.39 kg/Mg (0.630.77 lb/ton) of 

aluminum produced.

(3) PM limit. Emissions of PM from potlines must not exceed 

2.45 kg/Mg (4.9 lb/ton) of aluminum produced. 
15 

(4) Nickel limit. Emissions of nickel shall not exceed 0.035 

kg/Mg (0.07 lb/ton) of aluminum produced from each Soderberg 

potline at a primary aluminum reduction plant. 

(5) Arsenic limit. Emissions of arsenic shall not exceed 

0.003 kg/Mg (0.006 lb/ton) of aluminum produced from each 

Soderberg potline at a primary aluminum reduction plant. 

(6) PCB limit. Emissions of PCB shall not exceed 2.0 μg 

TEQ/ton of aluminum produced from each Soderberg potline at a 

primary aluminum reduction plant. 

(b) Paste production plants. The owner or operator shall 

meet the requirements in §63.843(b) for existing paste 

production plants.(1) The owner or operator shall meet the 

requirements in § 63.843(b)(1) through (3) for existing paste 

production plants and shall not discharge or cause to be 

discharged into the atmosphere any emissions of PM in excess of 

the limit in paragraph (b)(2) of this section. 

(2) Emissions of PM shall not exceed 0.0028 kg/Mg (0.0056 

lb/ton) of green anode. 

(c) Anode bake furnaces. The owner or operator shall not 

discharge or cause to be discharged into the atmosphere any 

emissions of TF, or POM in excess of the limits in paragraphs 

(c)(1) and (c)(2) of this sectionPM, POM or mercury in excess of 

the limits in paragraphs (c)(1) through (4) of this section. 
16 

(1) TF limit. Emissions of TF shall not exceed 0.01 kg/Mg 

(0.02 lb/ton) of green anode; and 

(2) POM limit. Emissions of POM shall not exceed 0.025 

kg/Mg (0.05 lb/ton) of green anode.; 

(3) PM limit. Emissions of PM shall not exceed 0.035 kg/Mg 

(0.07 lb/ton) of green anode; and 

(4) Mercury limit. Emissions of mercury shall not exceed 

1.7 μg/dscm.

(d) Pitch storage tanks. Each pitch storage tank shall be 

equipped with an emission control system designed and operated 

to reduce inlet emissions of POM by 95 percent or greater.

(e) COS limit. Emissions of COS must not exceed 1.55 kg/Mg 

(3.1 lb/ton) of aluminum produced for each potline.

(f) At all times, the owner or operator must operate and 

maintain any affected source, including associated air pollution 

control equipment and monitoring equipment, in a manner 

consistent with safety and good air pollution control practices 

for minimizing emissions. Determination of whether such 

operation and maintenance procedures are being used will be 

based on information available to the Administrator which may 

include, but is not limited to, monitoring results, review of 

operation and maintenance procedures, review of operation and 

maintenance records and inspection of the source.
17 

§ 63.845 Incorporation of new source performance stadards for 

potroom groups. 

(a) Applicability. The provisions in paragraphs (a) through 

(i) of this section shall apply to any Soderberg, CWPB2, and 

CWPB3 potline that adds a new potroom group to an existing 

potline or that is associated with a potroom group that meets 

the definition of “modified potroom group” or “reconstructed 

potroom group.” 

(1) The following shall not, by themselves, be considered 

to result in a potroom group modification: 

(i) Maintenance, repair, and replacement that the 

applicable regulatory authority determines to be routine for the 

potroom group; 

(ii) An increase in production rate of an existing potroom 

group, if that increase can be accomplished without a capital 

expenditure on that potroom group; 

(iii) An increase in the hours of operation; 

(iv) Use of an alternative fuel or raw material if, prior 

to the effective date of this subpart, the existing potroom 

group was designed to accommodate that alternative use; 

(v) The addition or use of any system or device whose 

primary function is the reduction of air pollutants, except when 

an emission control system is removed or is replaced by a system 
18 

that the applicable regulatory authority determines to be less 

environmentally beneficial; and 

(vi) The relocation or change in ownership of an existing 

potroom group. 

(2) The provisions in paragraphs (a)(2)(i) through 

(a)(2)(iv) of this section apply when the applicable regulatory 

authority must determine if a potroom group meets the definition 

of reconstructed potroom group. 

(i) “Fixed capital cost” means the capital needed to 

provide all the depreciable components. 

(ii) If an owner or operator of an existing potroom group 

proposes to replace components, and the fixed capital cost of 

the new components exceeds 50 percent of the fixed capital cost 

that would be required to construct a comparable entirely new 

potroom group, he/she shall notify the applicable regulatory 

authority of the proposed replacements. The notice must be 

postmarked 60 days (or as soon as practicable) before 

construction of the replacements is commenced and must include 

the following information: 

(A) Name and address of the owner or operator; 

(B) The location of the existing potroom group; 

(C) A brief description of the existing potroom group and 

the components that are to be replaced; 
19 

(D) A description of the existing air pollution control 

equipment and the proposed air pollution control equipment; 

(E) An estimate of the fixed capital cost of the 

replacements and of constructing a comparable entirely new 

potroom group; 

(F) The estimated life of the existing potroom group after 

the replacements; and 

(G) A discussion of any economic or technical limitations 

the potroom group may have in complying with the applicable 

standards of performance after the proposed replacements. 

(iii) The applicable regulatory authority will determine, 

within 30 days of the receipt of the notice required by 

paragraph (a)(2)(ii) of this section and any additional 

information he/she may reasonably require, whether the proposed 

replacement constitutes a reconstructed potroom group. 

(iv) The applicable regulatory authority's determination 

under paragraph (a)(2)(iii) of this section shall be based on: 

(A) The fixed capital cost of the replacements in 

comparison to the fixed capital cost that would be required to 

construct a comparable entirely new potroom group; 

(B) The estimated life of the potroom group after the 

replacements compared to the life of a comparable entirely new 

potroom group; 
20 

(C) The extent to which the components being replaced cause 

or contribute to the emissions from the potroom group; and 

(D) Any economic or technical limitations on compliance 

with applicable standards of performance that are inherent in 

the proposed replacements. 

(b) Lower TF emission limit. The owner or operator shall 

calculate a lower TF emission limit for any potline associated 

with the modified potroom group, reconstructed potroom group, or 

new potroom group using the following equation: 

L1=f1×LPG1+(1−f1)×LPL

Where: 

L1=the lower TF emission limit in kg/Mg (lb/ton); 

f1=the fraction of the potline's total aluminum production 

capacity that is contained within all modified potroom groups, 

reconstructed potroom groups, and new potroom groups; 

LPG1=0.95 kg/Mg (1.9 lb/ton) for prebake potlines and 1.0 kg/Mg 

(2.0 lb/ton) for Soderberg potlines; and 

LPL=the TF emission limit from §63.843(a)(1) for the appropriate 

potline subcategory that would have otherwise applied to the 

potline. 

(c) Upper TF emission limit. The owner or operator shall 

calculate an upper TF emission limit for any potline associated 

with the modified potroom group, reconstructed potroom group, or 

new potroom group using the following equation: 
21 

L2=f1×LPG2+(1−f1)×LPL

Where: 

L2=the upper TF emission limit in kg/Mg (lb/ton); and 

LPG2=1.25 kg/Mg (2.5 lb/ton) for prebake potlines and 1.3 kg/Mg 

(2.6 lb/ton) for Soderberg potlines. 

(d) Recalculation. The TF emission limits in paragraphs (b) 

and (c) of this section shall be recalculated each time a new 

potroom group is added to the potline and each time an 

additional potroom group meets the definition of “modified 

potroom group” or “reconstructed potroom group.” 

(e) Emission limitation. The owner or operator shall not 

discharge or cause to be discharged into the atmosphere 

emissions of TF from any potline associated with the modified 

potroom group, reconstructed potroom group, or new potroom group 

that exceed the lower emission limit calculated in paragraph (b) 

of this section, except that emissions less than the upper limit 

calculated in paragraph (c) of this section will be considered 

in compliance if the owner or operator demonstrates that 

exemplary operation and maintenance procedures were used with 

respect to the emission control system and that proper control 

equipment was operating at the potline during the performance 

test. 

(f) Report. Within 30 days of any performance test that 

reveals emissions that fall between the lower limit calculated 
22 

in paragraph (b) of this section and the upper limit calculated 

in paragraph (c) of this section, the owner or operator shall 

submit to the applicable regulatory authority a report 

indicating whether all necessary control devices were online and 

operating properly during the performance test, describing the 

operating and maintenance procedures followed, and setting forth 

any explanation for the excess emissions. 

(g) Procedures to determine TF emissions. The owner or 

operator shall determine TF emissions for the potline using the 

following procedures: 

(1) Determine the emission rate of TF in kg/Mg (lb/ton) 

from sampling secondary emissions and the primary control system 

for all new potroom groups, modified potroom groups, and 

reconstructed potroom groups using the procedures, equations, 

and test methods in §§63.847, 63.848, and 63.849. 

(2) Determine the emission rate of TF in kg/Mg (lb/ton) 

from sampling secondary emissions and the primary control system 

for potroom groups or sections of potroom groups within the 

potline that are not new potroom groups, modified potroom 

groups, or reconstructed potroom groups according to paragraphs 

(g)(2)(i) or (g)(2)(ii) of this section. 

(i) Determine the mass emission rate of TF in kg/Mg 

(lb/ton) from at least one potroom group within the potline that 

is not a new potroom group, modified potroom group, or 
23 

reconstructed potroom group using the procedures, equations, and 

test methods in §§63.847, 63.848, and 63.849, or 

(ii) Use the results of the testing required by paragraph 

(g)(1) of this section to represent the entire potline based on 

a demonstration that the results are representative of the 

entire potline. Representativeness shall be based on showing 

that all of the potroom groups associated with the potline are 

substantially equivalent in terms of their structure, 

operability, type of emissions, volume of emissions, and 

concentration of emissions. 

(3) Calculate the TF emissions for the potline in kg/Mg 

(lb/ton) based on the production-weighted average of the TF 

emission rates from paragraphs (g)(1) and (g)(2) of this section 

using the following equation: 

E=f1×EPG1+(1-f1)×EPL

where: 

E=the TF emission rate for the entire potline, kg/Mg (lb/ton); 

f1=the fraction of the potline's total aluminum production rate 

that is contained within all modified potroom groups, 

reconstructed potroom groups, and new potroom groups; 

EPG1=the TF emission rate from paragraph (g)(1) of this section 

for all modified potroom groups, reconstructed potroom groups, 

and new potroom groups, kg/Mg (lb/ton); and 
24 

EPL=the TF emission rate for the balance of the potline from 

paragraph (g)(2) of this section, kg/Mg (lb/ton). 

Compliance is demonstrated when TF emissions for the 

potline meet the requirements in paragraph (e) of this section. 

(4) As an alternative to sampling as required in paragraphs 

(g)(1) and (g)(2) of this section, the owner or operator may 

perform representative sampling of the entire potline subject to 

the approval of the applicable regulatory authority. Such 

sampling shall provide coverage by the sampling equipment of 

both the new, modified, or reconstructed potroom group and the 

balance of the potline. The coverage for the new, modified, or 

reconstructed potroom group must meet the criteria specified in 

the reference methods in §63.849. TF emissions shall be 

determined for the potline using the procedures, equations, and 

test methods in §§63.847, 63.848, and 63.849. Compliance is 

demonstrated when TF emissions for the potline meet the 

requirements in paragraph (e) of this section. 

(h) Opacity. Except as provided in paragraph (i) of this 

section, the owner or operator shall not discharge or cause to 

be discharged into the atmosphere from the modified potroom 

group, reconstructed potroom group, or new potroom group any 

emissions of gases that exhibit 10 percent opacity or greater. 
25 

(i) Alternative opacity limit. An alternative opacity limit 

may be established in place of the opacity limit in paragraph 

(h) of this section using the following procedures: 

(1) If the regulatory authority finds that a potline is in 

compliance with the applicable TF standard for which performance 

tests are conducted in accordance with the methods and 

procedures in §63.849 but during the time such performance tests 

are being conducted fails to meet any applicable opacity 

standard, the regulatory authority shall notify and advise the 

owner or operator that he/she may petition the regulatory 

authority within 10 days of receipt of notification to make 

appropriate adjustment to the opacity standard. 

(2) The regulatory authority will grant such a petition 

upon a demonstration by the owner or operator that the potroom 

group and associated air pollution control equipment were 

operated and maintained in a manner to minimize the opacity of 

emissions during the performance tests; that the performance 

tests were performed under the conditions established by the 

regulatory authority; and that the potroom group and associated 

air pollution control equipment were incapable of being adjusted 

or operated to meet the applicable opacity standard. 

(3) As indicated by the performance and opacity tests, the 

regulatory authority will establish an opacity standard for any 

potroom group meeting the requirements in paragraphs (i)(1) and 
26 

(i)(2) of this section such that the opacity standard could be 

met by the potroom group at all times during which the potline 

is meeting the TF emission limit. 

(4) The alternative opacity limit established in paragraph 

(i)(3) of this section shall not be greater than 20 percent 

opacity. 

§ 63.846 Emission averaging. 

(a) General. The owner or operator of an existing potline 

or anode bake furnace in a State that does not choose to exclude 

emission averaging in the approved operating permit program may 

demonstrate compliance by emission averaging according to the 

procedures in this section. 

(b) Potlines. The owner or operator may average TF 

emissions from potlines and demonstrate compliance with the 

limits in Table 1 of this subpart using the procedures in 

paragraphs (b)(1) and (b)(2) of this section. The owner or 

operator also may average POM emissions from potlines and 

demonstrate compliance with the limits in Table 2 of this 

subpart using the procedures in paragraphs (b)(1) and (b)(3) of 

this section.The owner or operator may average emissions from 

potlines and demonstrate compliance with the limits in Tables 1 

through 3 of this subpart using the procedures in paragraphs 

(b)(1) through (3) of this section.
27 

(1) Monthly average emissions of TF and/or quarterly 

average emissions of POM shall not exceed the applicable 

emission limit in Table 1 of this subpart (for TF emissions) 

and/or Table 2 of this subpart (for POM emissions). The emission 

rate shall be calculated based on the total emissions from all 

potlines over the period divided by the quantity of aluminum 

produced during the period, from all potlines comprising the 

averaging group. 

(2) To determine compliance with the applicable emission 

limit in Table 1 of this subpart for TF emissions, the owner or 

operator shall determine the monthly average emissions (in 

lb/ton) from each potline from at least three runs per potline 

each month for TF secondary emissions using the procedures and 

methods in §§63.847 and 63.849. The owner or operator shall 

combine the results of secondary TF monthly average emissions 

with the TF results for the primary control system and divide 

total emissions by total aluminum production. 

(3) To determine compliance with the applicable emission 

limit in Table 2 of this subpart for POM emissions, the owner or 

operator shall determine the quarterly average emissions (in 

lb/ton) from each potline from at least one run each month for 

POM emissions using the procedures and methods in §§63.847 and 

63.849. The owner or operator shall combine the results of 

secondary POM quarterly average emissions with the POM results 
28 

for the primary control system and divide total emissions by 

total aluminum production. 

(1) Semiannual average emissions of TF shall not exceed the 

applicable emission limit in Table 1 of this subpart. The 

emission rate shall be calculated based on the total primary and 

secondary emissions from all potlines comprising the averaging 

group over the period divided by the quantity of aluminum 

produced during the period, from all potlines comprising the 

averaging group. To determine compliance with the applicable 

emission limit in Table 1 of this subpart for TF emissions, the 

owner or operator shall determine the average emissions (in 

lb/ton) from each potline from at least three runs per potline 

semiannually for TF secondary emissions and at least three runs 

per potline primary control system each year using the 

procedures and methods in §§ 63.847 and 63.849. The owner or 

operator shall combine the results of secondary TF average 

emissions with the TF results for the primary control system and 

divide total emissions by total aluminum production.

(2) Semiannual average emissions of POM shall not exceed 

the applicable emission limit in Table 2 of this subpart. The 

emission rate shall be calculated based on the total primary and 

secondary emissions from all potlines comprising the averaging 

group over the period divided by the quantity of aluminum 

produced during the period, from all potlines comprising the 
29 

averaging group. To determine compliance with the applicable 

emission limit in Table 2 of this subpart for POM emissions, the 

owner or operator shall determine the average emissions (in 

lb/ton) from each potline from at least three runs per potline 

semiannually for POM secondary emissions and at least three runs 

per potline primary control system each year for POM primary 

emissions using the procedures and methods in §§ 63.847 and 

63.849. The owner or operator shall combine the results of 

secondary POM average emissions with the POM results for the 

primary control system and divide total emissions by total 

aluminum production.

(3) Semiannual average emissions of PM shall not exceed the 

applicable emission limit in Table 3 of this subpart. The 

emission rate shall be calculated based on the total primary and 

secondary emissions from all potlines comprising the potline 

group over the period divided by the quantity of aluminum 

produced during the period, from all potlines comprising the 

averaging group. To determine compliance with the applicable 

emission limit in Table 3 of this subpart for PM emissions, the 

owner or operator shall determine the average emissions (in 

lb/ton) from each potline from at least three runs per potline 

semiannually for PM secondary emissions and at least three runs 

per potline primary control system each year for PM primary 

emissions using the procedures and methods in §§ 63.847 and 
30 

63.849. The owner or operator shall combine the results of 

secondary PM average emissions with the PM results for the 

primary control system and divide total emissions by total 

aluminum production.

(c) Anode bake furnaces. The owner or operator may average 

TF emissions from anode bake furnaces and demonstrate compliance 

with the limits in Table 3 of this subpart using the procedures 

in paragraphs (c)(1) and (c)(2) of this section. The owner or 

operator also may average POM emissions from anode bake furnaces 

and demonstrate compliance with the limits in Table 3 of this 

subpart using the procedures in paragraphs (c)(1) and (c)(2) of 

this section.The owner or operator may average TF emissions from 

anode bake furnaces and demonstrate compliance with the limits 

in Table 4 of this subpart using the procedures in paragraphs 

(c)(1) and (2) of this section. The owner or operator also may 

average POM emissions from anode bake furnaces and demonstrate 

compliance with the limits in Table 4 of this subpart using the 

procedures in paragraphs (c)(1) and (2) of this section. The 

owner or operator also may average PM emissions from anode bake 

furnaces and demonstrate compliance with the limits in Table 4 

of this subpart using the procedures in paragraphs (c)(1) and 

(2) of this section.

(1) Annual emissions of TF, and/or POM, and/or PM from a 

given number of anode bake furnaces making up each averaging 
31 

group shall not exceed the applicable emission limit in Table 34

of this subpart in any one year; and 

(2) To determine compliance with the applicable emission 

limit in Table 34 of this subpart for anode bake furnaces, the 

owner or operator shall determine TF and/or POM TF, POM and/or 

PM emissions from the control device for each furnace at least 

once a year using the procedures and methods in §§63.847 and 

63.849. 

(d) Implementation plan. The owner or operator shall 

develop and submit an implementation plan for emission averaging 

to the applicable regulatory authority for review and approval 

according to the following procedures and requirements: 

(1) Deadlines. The owner or operator must submit the 

implementation plan no later than 6 months before the date that 

the facility intends to comply with the emission averaging 

limits. 

(2) Contents. The owner or operator shall include the 

following information in the implementation plan or in the 

application for an operating permit for all emission sources to 

be included in an emissions average: 

(i) The identification of all emission sources (potlines or 

anode bake furnaces) in the average; 

(ii) The assigned TF or POM, or PM emission limit for each 

averaging group of potlines or anode bake furnaces; 
32 

(iii) The specific control technologiesy or pollution 

prevention measures to be used for each emission source in the 

averaging group and the date of its installation or application. 

If the pollution prevention measures reduces or eliminates

emissions from multiple sources, the owner or operator must 

identify each source; 

(iv) The test plan for the measurement of TF, or POM, or PM

emissions in accordance with the requirements in §63.847(b); 

(v) The operating parameters to be monitored for each 

control system or device and a description of how the operating 

limits will be determined; 

(vi) If the owner or operator requests to monitor an 

alternative operating parameter pursuant to §63.848(l): 

(A) A description of the parameter(s) to be monitored and 

an explanation of the criteria used to select the parameter(s); 

and 

(B) A description of the methods and procedures that will 

be used to demonstrate that the parameter indicates proper 

operation of the control device; the frequency and content of 

monitoring, reporting, and recordkeeping requirements; and a 

demonstration, to the satisfaction of the applicable regulatory 

authority, that the proposed monitoring frequency is sufficient 

to represent control device operating conditions; and 
33 

(vii) A demonstration that compliance with each of the 

applicable emission limit(s) will be achieved under 

representative operating conditions. 

(3) Approval criteria. Upon receipt, the regulatory 

authority shall review and approve or disapprove the plan or 

permit application according to the following criteria: 

(i) Whether the content of the plan includes all of the 

information specified in paragraph (d)(2) of this section; and 

(ii) Whether the plan or permit application presents 

sufficient information to determine that compliance will be 

achieved and maintained. 

(4) Prohibitions. The applicable regulatory authority shall 

not approve an implementation plan or permit application 

containing any of the following provisions: 

(i) Any averaging between emissions of differing pollutants 

or between differing sources. Emission averaging shall not be 

allowed between TF and POMTF, POM and/or PM, and emission 

averaging shall not be allowed between potlines and bake 

furnaces; 

(ii) The inclusion of any emission source other than an 

existing potline or existing anode bake furnace or the inclusion 

of any potline or anode bake plant not subject to the same 

operating permit; or
34 

(iii) The inclusion of any potline or anode bake furnace 

while it is shut down.; or

(iv) The inclusion of any periods of startup, shutdown, or 

malfunction, as described in the startup, shutdown, and 

malfunction plan required by §63.850(c), in the emission 

calculations.

(5) Term. Following review, the applicable regulatory 

authority shall approve the plan or permit application, request 

changes, or request additional information. Once the applicable 

regulatory authority receives any additional information 

requested, the applicable regulatory authority shall approve or 

disapprove the plan or permit application within 120 days. 

(i) The applicable regulatory authority shall approve the 

plan for the term of the operating permit; 

(ii) To revise the plan prior to the end of the permit 

term, the owner or operator shall submit a request to the 

applicable regulatory authority; and 

(iii) The owner or operator may submit a request to the 

applicable regulatory authority to implement emission averaging 

after the applicable compliance date. 

(6) Operation. While operating under an approved 

implementation plan, the owner or operator shall monitor the 

operating parameters of each control system, keep records, and 
35 

submit periodic reports as required for each source subject to 

this subpart. 

§ 63.847 Compliance provisions. 

(a) Compliance dates . The owner or operator of a primary 

aluminum plant must comply with the requirements of this subpart 

by the applicable compliance date in paragraph (a)(1), (a)(2) or 

(a)(4) of this section: 

(1) October 7, 1999, for an owner or operator of an 

existing plant or source; 

(2) October 9, 2000, for an existing source, provided the 

owner or operator demonstrates to the satisfaction of the 

applicable regulatory authority that additional time is needed 

to install or modify the emission control equipment; 

(1) Except as noted in paragraph (2) of this section, the 

compliance date for an owner or operator of an existing plant or 

source subject to the provisions of this subpart is October 7, 

1999. 

(2) The compliance dates for existing plants and sources 

are: 

(i) [Insert date of publication of final rule] for the 

malfunction provisions of §§ 63.850(d)(2) and (e)(4)(xvi) and 

(xvii) and the electronic reporting provisions of §§ 63.850(b), 

(c) and (f) which became effective [Insert date of publication 

of final rule]. 
36 

(ii) [Insert date 1 year after date of publication of final 

rule] for potline work practice standards in § 63.854 and the 

COS emission limit provisions of § 63.843(e); for anode bake 

furnace startup practices in § 63.847(l) and PM emission limits 

in § 63.843(c)(3); for Soderberg potline PM and PCB emission 

limits in §§ 63.843(a)(3)(v) and (a)(6); and for paste 

production plant startup practices in § 63.847(m) and PM 

emission limits in § 63.843(b)(4) which became effective [Insert 

date of publication of final rule]. 

(iii) [Insert date 2 years after date of publication of 

final rule] for prebake potline POM emission limits in 

§§ 63.843(a)(2)(iv) through (vii); for Soderberg potline POM, As 

and Ni emission limits in §§ 63.843(a)(2)(iii), (a)(4) and (5); 

for prebake potline PM emission limits in § 63.843(a)(3); for 

anode bake furnace Hg emission limits in § 63.843(c)(4); and for 

the pitch storage tank POM limit provisions of § 63.843(d) which 

became effective [Insert date of publication of final rule]. 

(3) October 8, 2001, for an existing source that is granted 

an extension by the regulatory authority under section 

112(i)(3)(B) of the Act; or[Reserved]

(4) Upon startup, for an owner or operator of a new or 

reconstructed source.
37 

(5) Except as provided in paragraphs (a)(6) and (7) of this 

section, a new affected source is one for which construction or 

reconstruction commenced after September 26, 1996.

(6) For the purposes of compliance with the emission 

standards for PM, a new affected potline, anode bake furnace or 

paste production plant is one for which construction or 

reconstruction commenced after December 8, 2014.

(7) For the purposes of compliance with the emission 

standards for POM and COS, a new affected prebake potline is one 

for which construction or reconstruction commenced after 

December 8, 2014.

(8) For the purposes of compliance with the emission 

standards for As, Ni and POM, a new affected Soderberg potline 

is one for which construction or reconstruction commenced after 

December 8, 2014.

(9) For the purposes of compliance with the emission 

standards for Hg, a new affected anode bake furnace is one for 

which construction or reconstruction commenced after December 8, 

2014.

(b) Test plan. The owner or operator shall prepare a sitespecific test plan prior to the initial performance test 

according to the requirements of §63.7(c) of this part. The test 

plan must include procedures for conducting the initial 

performance test and for subsequent performance tests required 
38 

in §63.848 for emission monitoring. In addition to the 

information required by §63.7, the test plan shall include: 

(1) Procedures to ensure a minimum of three runs are 

performed annually for the primary control system for each 

source; 

(2) For a source with a single control device exhausted 

through multiple stacks, procedures to ensure that at least 

three runs are performed annually by a representative sample of 

the stacks satisfactory to the applicable regulatory authority; 

(3) For multiple control devices on a single source, 

procedures to ensure that at least one run is performed annually 

for each control device by a representative sample of the stacks 

satisfactory to the applicable regulatory authority; 

(4) Procedures for sampling single stacks associated with 

multiple anode bake furnaces; 

(5) For plants with roof scrubbers, procedures for rotating 

sampling among the scrubbers or other procedures to obtain 

representative samples as approved by the applicable regulatory 

authority; 

(6) For a VSS1 potline, procedures to ensure that one fan 

(or one scrubber) per potline is sampled for each run;[Reserved]

(7) For a SWPB potline, procedures to ensure that the 

average of the sampling results for two fans (or two scrubbers) 

per potline is used for each run; and 
39 

(8) Procedures for establishing the frequency of testing to 

ensure that at least one run is performed before the 15th of the 

month, at least one run is performed after the 15th of the 

month, and that there are at least 6 days between two of the 

runs during the month, or that secondary emissions are measured 

according to an alternate schedule satisfactory to the 

applicable regulatory authority. 

(c) Performance test dates . Following approval of the 

site-specific test plan, the owner or operator must conduct a 

performance test to demonstrate initial compliance according to 

the procedures in paragraph (d) of this section. If a 

performance test has been conducted on the primary control 

system for potlines, or for the anode bake furnace within the 12 

months prior to the compliance date, the anode bake furnace, the 

paste production plant, or (if applicable) the pitch storage 

tank control device within the 12 months prior to the compliance 

date, the results of that performance test may be used to 

demonstrate initial compliance. The owner or operator must 

conduct the performance test: 

(1) During the first month following the compliance date 

for an existing potline (or potroom group) or anode bake 

furnace;, anode bake furnace, paste production plant or pitch 

storage tank.
40 

(2) By the date determined according to the requirements in 

paragraph (c)(2)(i), (ii), or (iii) or (iv) of this section for 

a new or reconstructed potline, anode bake furnace, or pitch 

storage tank (for which the owner or operator elects to conduct 

an initial performance test): 

(i) By the 180th day following startup for a potline or 

potroom group. The 180-day period starts when the first pot in a 

potline or potroom group is energized. 

(ii) By the 45th day from the start of the second anode 

bake cycle (but no later than the 180th day from the startup of 

the anode bake furnace). 

(iii) By the 30th day following startup for a pitch storage 

tank. The 30-day period starts when the tank is first used to 

store pitch.

(iv) By the 30th day following startup of a paste 

production plant. The 30-day period starts when the paste 

production plant produces green anodes.

(3) By the date determined according to the requirements in 

paragraph (c)(3)(i) or (ii) (ii), (iii) or (iv) of this section 

for an existing potline or anode bake furnace that was shut down 

at the time compliance would have otherwise been required and is 

subsequently restarted: 
41 

(i) By the 180th day following startup for a potline or 

potroom group. The 180-day period starts when the first pot in a 

potline or potroom group is energized. 

(ii) By the 45th day from the start of the second anode 

bake cycle (but no later than the 180th day from the startup of 

the anode bake furnace).

(iii) By the 30th day following startup of a paste 

production plant. The 30-day period starts when the paste 

production plant produces green anodes. 

(iv) By the 30th day following startup for a pitch storage 

tank. The 30-day period starts when the tank is first used to 

store pitch.

(d) Performance test requirements. The initial performance 

test and all subsequent performance tests shall be conducted in 

accordance with the requirements of the general provisions in 

subpart A of this part, the approved test plan, and the 

procedures in this section. Performance tests must be conducted 

under such conditions as the Administrator specifies to the 

owner or operator based on representative performance of the 

affected source for the period being tested. Upon request, the 

owner or operator must make available to the Administrator such 

records as may be necessary to determine the conditions of 

performance tests.
42 

(1) TF emissions from potlines. For each potline, the owner 

or operator shall measure and record the emission rate of TF 

exiting the outlet of the primary control system for each 

potline and the rate of secondary emissions exiting through each 

roof monitor, or for a plant with roof scrubbers, exiting 

through the scrubbers. Using the equation in paragraph (e)(1) of 

this section, the owner or operator shall compute and record the 

average of at least three runs each month for secondary 

emissions and at least three runs each year for the primary 

control system to determine compliance with the applicable 

emission limit. Compliance is demonstrated when the emission 

rate of TF is equal to or less than the applicable emission 

limit in §63.843, §63.844, or §63.846.(1) TF, POM and PM 

emissions from potlines. For each potline, the owner or operator 

shall measure and record the emission rates of TF, POM and PM 

exiting the outlet of the primary control system and the rate of 

secondary emissions exiting through each roof monitor, or for a 

plant with roof scrubbers, exiting through the scrubbers. Using 

the equation in paragraph (e)(1) of this section, the owner or 

operator shall compute and record the average of at least three 

runs semiannually for secondary emissions and at least three 

runs each year for the primary control system to determine 

compliance with the applicable emission limit. Compliance is 

demonstrated when the emission rates of TF, POM, and PM are 
43 

equal to or less than the applicable emission limits in §

63.843, § 63.844, or § 63.846.

(2) POM emissions from Soderberg potlines. For each 

Soderberg (HSS, VSS1, and VSS2) potline, the owner or operator 

shall measure and record the emission rate of POM exiting the 

primary emission control system and the rate of secondary 

emissions exiting through each roof monitor, or for a plant with 

roof scrubbers, exiting through the scrubbers. Using the 

equation in paragraph (e)(2) of this section, the owner or 

operator shall compute and record the average of at least three 

runs each quarter (one run per month) for secondary emissions 

and at least three runs each year for the primary control system 

to determine compliance with the applicable emission limit. 

Compliance is demonstrated when the emission rate of POM is 

equal to or less than the applicable emission limit in §63.843, 

§63.844, or §63.846.[Reserved]

(3) Previous control device tests. If the owner or operator 

has performed more than one test of primary emission control 

device(s) for a potline or for a bake furnace during the 

previous consecutive 12 months, the average of all runs 

performed in the previous 12-month period shall be used to 

determine the contribution from the primary emission control 

system. 
44 

(4) TF and POM emissions from anode bake furnaces. For each 

anode bake furnace, the owner or operator shall measure and 

record the emission rate of TF and POM exiting the exhaust 

stacks(s) of the primary emission control system for each anode 

bake furnace. Using the equations in paragraphs (e)(3) and 

(e)(4) of this section, the owner or operator shall compute and 

record the average of at least three runs each year to determine 

compliance with the applicable emission limits for TF and POM. 

Compliance is demonstrated when the emission rates of TF and POM 

are equal to or less than the applicable TF and POM emission 

limits in §63.843, §63.844, or §63.846.(4) TF, POM, PM and Hg 

emissions from anode bake furnaces. For each anode bake furnace, 

the owner or operator shall measure and record the emission rate 

of TF, POM, PM and Hg exiting the exhaust stacks(s) of the 

primary emission control system. In accordance with paragraphs 

(e)(3) and (4) of this section, the owner or operator shall 

compute and record the average of at least three runs each year 

to determine compliance with the applicable emission limits for 

TF, POM, PM and Hg. Compliance is demonstrated when the emission 

rates of TF, POM, PM and Hg are equal to or less than the 

applicable TF, POM, PM and Hg emission limits in § 63.843, 

§ 63.844 or § 63.846. 

(5) Nickel emissions from VSS2 Potlines and new Soderberg 

potlines. (i) For each VSS2 potline, and for each new Soderberg 
45 

potline, the owner or operator must measure and record the 

emission rate of nickel exiting the primary emission control 

system and the rate of secondary emissions of nickel exiting 

through each roof monitor, or for a plant with roof scrubbers, 

exiting through the scrubbers. Using the equation in paragraph 

(e)(1) of this section, the owner or operator must compute and 

record the average of at least three runs each year for 

secondary emissions and at least three runs each year for 

primary emissions. 

(ii) Compliance is demonstrated when the emissions of 

nickel are equal to or less than the applicable emission limit 

in § 63.843(a)(4) or § 63.844(a)(4). 

(6) Arsenic emissions from VSS2 Potlines and from new 

Soderberg potlines. (i) For each VSS2 potline, and for each new 

Soderberg potline, the owner or operator must measure and record 

the emission rate of arsenic exiting the primary emission 

control system and the rate of secondary emissions of arsenic 

exiting through each roof monitor, or for a plant with roof 

scrubbers, exiting through the scrubbers. Using the equation in 

paragraph (e)(1) of this section, the owner or operator must 

compute and record the average of at least three runs each year 

for secondary emissions and at least three runs each year for 

primary emissions. 
46 

(ii) Compliance is demonstrated when the emissions of 

arsenic are equal to or less than the applicable emission limit 

in § 63.843(a)(5) or § 63.844(a)(5). 

(7) PCB emissions from VSS2 Potlines and from new Soderberg 

potlines. (i) For each VSS2 potline, and for each new Soderberg 

potline, the owner or operator must measure and record the 

emission rate of PCB exiting the primary emission control system 

and the rate of secondary emissions of PCB exiting through each 

roof monitor, or for a plant with roof scrubbers, exiting 

through the scrubbers. Using the equation in paragraph (e)(1) of 

this section, the owner or operator must compute and record the 

average of at least three runs each year for secondary emissions 

and at least three runs each year for primary emissions. 

(ii) Compliance is demonstrated when the emissions of PCB 

are equal to or less than the applicable emission limit in 

§ 63.843(a)(6) or § 63.844(a)(6).

(e) Equations. The owner or operator shall determine 

compliance with the applicable TF, and POM POM, PM, nickel, 

arsenic or PCB emission limits using the following equations and 

procedures: 

(1) Compute the emission rate (Ep) of TF from each potline 

using Equation 1: 
47 

Where: 

Ep=emission rate of TF from a potline, kg/Mg (lb/ton); 

Cs1=concentration of TF from the primary control system, mg/dscm 

(mg/dscf); 

Qsd=volumetric flow rate of effluent gas corresponding to the 

appropriate subscript location, dscm/hr (dscf/hr); 

Cs2=concentration of TF as measured for roof monitor emissions, 

mg/dscm (mg/dscf); 

P=aluminum production rate, Mg/hr (ton/hr); 

K=conversion factor, 106 mg/kg (453,600 mg/lb); 

1= subscript for primary control system effluent gas; and 

2= subscript for secondary control system or roof monitor 

effluent gas. 

(1) Compute the emission rate (Ep) of TF, POM, PM, nickel, 

arsenic or PCB from each potline using Equation 1: 

Where: 

Ep = emission rate of TF, POM, PM, nickel or arsenic from a 

potline, kg/Mg (lb/ton) (or μg TEQ/ton for PCB); 

Cs1 = concentration of TF, POM, PM, nickel or arsenic from the 

primary control system, mg/dscm (mg/dscf) (or μg TEQ/dscf for 

PCB); 
48 

Qsd = volumetric flow rate of effluent gas corresponding to the 

appropriate subscript location, dscm/hr (dscf/hr); 

Cs2 = concentration of TF, POM, PM, nickel or arsenic as measured 

for roof monitor emissions, mg/dscm (mg/dscf) (or μg TEQ/dscf 

for PCB); 

P = aluminum production rate, Mg/hr (ton/hr); 

K = conversion factor, 106 mg/kg (453,600 mg/lb) for TF, POM, PM, 

nickel or arsenic (= 1 for PCB); 

1 = subscript for primary control system effluent gas; and 

2 = subscript for secondary control system or roof monitor 

effluent gas.

(2) Compute the emission rate of POM from each potline 

using Equation 1, 

Where: 

Ep= emission rate of POM from the potline, kg/mg (lb/ton); and 

Cs= concentration of POM, mg/dscm (mg/dscf). POM emission data 

collected during the installation and startup of a cathode shall 

not be included in Cs.[Reserved] 

(3) Compute the emission rate (Eb) of TF from each anode 

bake furnace using Equation 2, 

Where: 

Eb= emission rate of TF, kg/mg (lb/ton) of green anodes produced; 
49 

Cs= concentration of TF, mg/dscm (mg/dscf); 

Qsd= volumetric flow rate of effluent gas, dscm/hr (dscf/hr); 

Pb= quantity of green anode material placed in the furnace, mg/hr 

(ton/hr); and 

K = conversion factor, 106 mg/kg (453,600 mg/lb). 

(4) Compute the emission rate of POM from each anode bake 

furnace using Equation 2, 

Where: 

Cs= concentration of POM, mg/dscm (mg/dscf). 

(3) Compute the emission rate (Eb) of TF, POM or PM from 

each anode bake furnace using Equation 2, 

Where: 

Eb = emission rate of TF, POM or PM, kg/mg (lb/ton) of green 

anodes; 

Cs = concentration of TF, POM or PM, mg/dscm (mg/dscf); 

Qsd = volumetric flow rate of effluent gas, dscm/hr (dscf/hr); 

Pb = quantity of green anode material placed in the furnace, 

mg/hr (ton/hr); and 

K = conversion factor, 106 mg/kg (453,600 mg/lb). 

(4) Compliance with the anode bake furnace Hg emission 

standard is demonstrated if the Hg concentration of the exhaust 

from the anode bake furnace control device is equal to or less 
50 

3

( )

( ) Equation P KC Q E

b

s sd

PMpp 

 

than the applicable concentration standard in § 63.843(c)(4) or 

§ 63.844(c)(4). 

(5) Determine the weight of the aluminum tapped from the 

potline and the weight of the green anode material placed in the 

anode bake furnace using the monitoring devices required in 

§63.848(j). 

(6) Determine the aluminum production rate (P) by dividing 

the number of hours in the calendar month into the weight of 

aluminum tapped from the potline during the calendar month that 

includes the three runs of a performance test. 

(7) Determine the rate of green anode material introduced 

into the furnace by dividing the number of operating hours in 

the calendar month into the weight of green anode material used 

during the calendar month in which the performance test was 

conducted.

(8) Compute the emission rate (EPMpp) of PM from each paste 

production plant using Equation 3, 

Where: 

EPMpp = emission rate of PM, kg/mg (lb/ton) of green anode 

material exiting the paste production plant; 

Cs = concentration of PM, mg/dscm (mg/dscf); 

Qsd = volumetric flow rate of effluent gas, dscm/hr (dscf/hr); 
51 

Pb = quantity of green anode material exiting the paste 

production plant, mg/hr (ton/hr); and 

K = conversion factor, 106 mg/kg (453,600 mg/lb).

(f) Paste production plants. (1) Initial compliance with 

the standards for existing and new paste production plants in 

§§63.843(b) and 63.844(b) will be demonstrated through site 

inspection(s) and review of site records by the applicable 

regulatory authority.

(2) For each paste production plant, the owner or operator 

shall measure and record the emission rate of PM exiting the 

exhaust stacks(s) of the primary emission control system. Using 

the equation in paragraph (e)(8) of this section, the owner or 

operator shall compute and record the average of at least three 

runs each year to determine compliance with the applicable 

emission limits for PM. Compliance with the PM standards for 

existing and new paste production plants is demonstrated when 

the PM emission rates are less than or equal to the applicable 

PM emission limits in §§ 63.843(b)(4) and 63.844(b)(2). 

(g) Pitch storage tanks. The owner or operator shall 

demonstrate initial compliance with the standard for pitch 

storage tanks in §§ 63.843(d) and 63.844(d) by preparing a 

design evaluation or by conducting a performance test. The owner 

or operator shall submit for approval by the regulatory 

authority the information specified in paragraph (g)(1) of this 
52 

section, along with the information specified in paragraph 

(g)(2) of this section where a design evaluation is performed or 

the information specified in paragraph (g)(3) of this section 

where a performance test is conducted. 

(1) A description of the parameters to be monitored to 

ensure that the control device is being properly operated and 

maintained, an explanation of the criteria used for selection of 

that parameter (or parameters), and the frequency with which 

monitoring will be performed; and 

(2) Where a design evaluation is performed, documentation 

demonstrating that the control device used achieves the required 

control efficiency during reasonably expected maximum filling 

rate. The documentation shall include a description of the gas 

stream that enters the control device, including flow and POM 

content under varying liquid level conditions, and the 

information specified in paragraphs (g)(2)(i) through (g)(2)(vi) 

of this section, as applicable. 

(i) If the control device receives vapors, gases, or 

liquids, other than fuels, from emission points other than pitch 

storage tanks, the efficiency demonstration is to include 

consideration of all vapors, gases, and liquids, other than 

fuels, received by the control device; 

(ii) If an enclosed combustion device with a minimum 

residence time of 0.5 seconds and a minimum temperature of 760 
53 

°C (1,400 °F) is used to meet the emission reduction requirement 

specified in § 63.843(d) and § 63.844(d), documentation that 

those conditions exist is sufficient to meet the requirements of 

§ 63.843(d) and §63.844(d); 

(iii) Except as provided in paragraph (g)(2)(ii) of this 

section, for thermal incinerators, the design evaluation shall 

include the autoignition temperature of the organic HAP, the 

flow rate of the organic HAP emission stream, the combustion 

temperature, and the residence time at the combustion 

temperature; 

(iv) If the pitch storage tank is vented to the emission 

control system installed for control of emissions from the paste 

production plant pursuant to §63.843(b) or §63.844(b)(1), 

documentation of compliance with the requirements of §63.843(b) 

is sufficient to meet the requirements of § 63.843(d) or 

§63.844(d); 

(v) For carbon adsorbers, the design evaluation shall 

include the affinity of the organic vapors for carbon, the 

amount of carbon in each bed, the number of beds, the humidity 

of the feed gases, the temperature of the feed gases, the flow 

rate of the organic HAP emission stream, and if applicable, the 

desorption schedule, the regeneration stream pressure or 

temperature, and the flow rate of the regeneration stream. For 

vacuum desorption, the pressure drop shall be included; and 
54 

(vi) For condensers, the design evaluation shall include 

the final temperature of the organic HAP vapors, the type of 

condenser, and the design flow rate of the organic HAP emission 

stream. 

(3) If a performance test is conducted, the owner or 

operator shall determine the control efficiency for POM during 

tank loading using Method 315 in appendix A to this part. The 

owner or operator shall include the following information: 

(i) Identification of the pitch storage tank and control 

device for which the performance test will be submitted; and 

(ii) Identification of the emission point(s) that share the 

control device with the pitch storage tank and for which the 

performance test will be conducted. 

(h) Selection of monitoring parameters. The owner or 

operator shall determine the operating limits and monitoring 

frequency for each control device that is to be monitored as 

required in §63.848(f). 

(1) For potlines and anode bake furnaces, the owner or 

operator shall determine upper and/or lower operating limits, as 

appropriate, for each monitoring device for the emission control 

system from the values recorded during each of the runs 

performed during the initial performance test and from 

historical data from previous performance tests conducted by the 

methods specified in this subpart. 
55 

(2) For a paste production plant, the owner or operator 

shall specify and provide the basis or rationale for selecting 

parameters to be monitored and the associated operating limits 

for the emission control device. 

(3) The owner or operator may redetermine the upper and/or 

lower operating limits, as appropriate, based on historical data 

or other information and submit an application to the applicable 

regulatory authority to change the applicable limit(s). The 

redetermined limits shall become effective upon approval by the 

applicable regulatory authority.

(i) [Reserved] 

(j) Carbonyl sulfide (COS) emissions. The owner operator 

must calculate, for each potline, the emission rate of COS for 

each calendar month of operation using Equation 4: 

    S (Equation 4) Z

Y ECOS K    

 



  

Where: 

ECOS = the emission rate of COS during the calendar month, pounds 

per ton of aluminum produced; 

K = factor accounting for molecular weights and conversion of 

sulfur to carbonyl sulfide = 234; 

Y = the mass of anode consumed in the potline during the 

calendar month, tons; 
56 

Z = the mass of aluminum produced by the potline during the 

calendar month, tons; and 

S = the weighted average fraction of sulfur in the anode coke 

consumed in the production of aluminum during the calendar month 

(e.g., if the weighted average sulfur content of the anode coke 

consumed during the calendar month was 2.5 percent, then S = 

0.025). The weight of anode coke used during the calendar month 

of each different concentration of sulfur is used to calculate 

the overall weighted average fraction of sulfur. 

Compliance is demonstrated if the calculated value of ECOS

is less than the applicable standard for COS emissions in 

§§ 63.843(e) and 63.844(e). 

(k) Startup of potlines. The owner or operator must develop 

a written startup plan as described in § 63.854(b) that contains 

specific procedures to be followed during startup periods of 

potline(s). Compliance with the applicable standards in 

§ 63.854(b) will be demonstrated through site inspection(s) and 

review of site records by the regulatory authority. 

(l) Startup of anode bake furnaces. The owner or operator 

must develop a written startup plan as described in paragraphs 

(l)(1) through (4) of this section, to be followed during 

startup periods of bake furnaces. Compliance with the startup 

plan will be demonstrated through site inspection(s) and review 

of site records by the regulatory authority. The written startup 
57 

plan must contain specific procedures to be followed during 

startup periods of anode bake furnaces, including the following: 

(1) A requirement to develop an anode bake furnace startup 

schedule. 

(2) Records of time, date, duration of anode bake furnace 

startup and any nonroutine actions taken during startup of the 

furnaces. 

(3) A requirement that the associated emission control 

system be operating within normal parametric limits prior to 

startup of the anode bake furnace. 

(4) A requirement to take immediate actions to stop the 

startup process as soon as practicable and continue to comply 

with § 63.843(f) or § 63.844(f) if the associated emission 

control system is off line at any time during startup. The anode 

bake furnace restart may resume once the associated emission 

control system is back on line and operating within normal 

parametric limits. 

(m) Startup of paste production plants. The owner or 

operator must develop a written startup plan as described in 

paragraphs (m)(1) through (3) of this section, to be followed 

during startup periods for paste production plants. Compliance 

with the startup plan will be demonstrated through site 

inspection(s) and review of site records by the regulatory 

authority. The written startup plan must contain specific 
58 

procedures to be followed during startup periods of paste 

production plants, including the following: 

(1) Records of time, date, duration of paste production 

plant startup and any nonroutine actions taken during startup of 

the paste production plants. 

(2) A requirement that the associated emission control 

system be operating within normal parametric limits prior to 

startup of the paste production plant. 

(3) A requirement to take immediate actions to stop the 

startup process as soon as practicable and continue to comply 

with § 63.843(f) or § 63.844(f) if the associated emission 

control system is off line at any time during startup. The paste 

production plant restart may resume once the associated emission 

control system is back on line and operating within normal 

parametric limits.

§ 63.848 Emission monitoring requirements. 

(a) TF emissions from potlines. Using the procedures in 

§63.847 and in the approved test plan, the owner or operator 

shall monitor emissions of TF from each potline by conducting 

monthly performance tests. The owner or operator shall compute 

and record the monthly average from at least three runs for 

secondary emissions and the previous 12-month average of all 

runs for the primary control system to determine compliance with 

the applicable emission limit. The owner or operator must 
59 

include all valid runs in the monthly average. The duration of 

each run for secondary emissions must represent a complete 

operating cycle. 

(b) POM emissions from Soderberg potlines. Using the 

procedures in §63.847 and in the approved test plan, the owner 

or operator shall monitor emissions of POM from each Soderberg 

(HSS, VSS1, and VSS2) potline every three months. The owner or 

operator shall compute and record the quarterly (3-month) 

average from at least one run per month for secondary emissions 

and the previous 12-month average of all runs for the primary 

control systems to determine compliance with the applicable 

emission limit. The owner or operator must include all valid 

runs in the quarterly (3-month) average. The duration of each 

run for secondary emissions must represent a complete operating 

cycle. The primary control system must be sampled over an 8-hour 

period, unless site-specific factors dictate an alternative 

sampling time subject to the approval of the regulatory 

authority. 

(c) TF and POM emissions from anode bake furnaces. Using 

the procedures in §63.847 and in the approved test plan, the 

owner or operator shall monitor TF and POM emissions from each 

anode bake furnace on an annual basis. The owner or operator 

shall compute and record the annual average of TF and POM 

emissions from at least three runs to determine compliance with 
60 

the applicable emission limits. The owner or operator must 

include all valid runs in the annual average. 

(d) Similar potlines. As an alternative to monthly 

monitoring of TF or POM secondary emissions from each potline 

using the test methods in §63.849, the owner or operator may 

perform monthly monitoring of TF or POM secondary emissions from 

one potline using the test methods in §§63.849 (a) or (b) to 

represent the performance of similar potline(s). The similar 

potline(s) shall be monitored using an alternative method that 

meets the requirements of paragraphs (d)(1) through (d)(7) of 

this section. Two or more potlines are similar if the owner or 

operator demonstrates that their structure, operability, type of 

emissions, volume of emissions, and concentration of emissions 

are substantially equivalent. 

(a) TF and PM emissions from potlines. Using the procedures 

in § 63.847 and in the approved test plan, the owner or operator 

shall monitor emissions of TF and PM from each potline by 

conducting annual performance tests on the primary control 

system and semiannual performance tests on the secondary 

emissions. The owner or operator shall compute and record the 

average semiannually from at least three runs for secondary 

emissions and the average from at least three runs for the 

primary control system to determine compliance with the 

applicable emission limit. The owner or operator must include 
61 

all valid runs in the semiannual average. The duration of each 

run for secondary emissions must represent a complete operating 

cycle. Potline emissions shall be recorded as the sum of the 

average of at least three runs from the primary control system 

and the average of at least three runs from the roof monitor or 

secondary emissions control device. 

(b) POM emissions from potlines. Using the procedures in 

§ 63.847 and in the approved test plan, the owner or operator 

must monitor emissions of POM from each potline stack annually 

and secondary potline POM emissions semiannually. The owner or 

operator must compute and record the semiannual average from at 

least three runs for secondary emissions and at least three runs 

for the primary control systems to determine compliance with the 

applicable emission limit. The owner or operator must include 

all valid runs in the semiannual average. The duration of each 

run for secondary emissions must represent a complete operating 

cycle. The primary control system must be sampled over an 8-hour 

period, unless site-specific factors dictate an alternative 

sampling time subject to the approval of the regulatory 

authority. Potline emissions shall be recorded as the sum of the 

average of at least three runs from the primary control system 

and the average of at least three runs from the roof monitor or 

secondary emissions control device. 
62 

(c) TF, PM, Hg and POM emissions from anode bake furnaces. 

Using the procedures in §63.847 and in the approved test plan, 

the owner or operator shall determine TF, PM, Hg and POM 

emissions from each anode bake furnace on an annual basis. The 

owner or operator shall compute and record the annual average of 

TF, PM, Hg and POM emissions from at least three runs to 

determine compliance with the applicable emission limits. A 

minimum of four dscm per run must be collected for monitoring of 

Hg emissions. The owner or operator must include all valid runs 

in the annual average. 

(d) Similar potlines. As an alternative to semiannual 

monitoring of TF, POM or PM secondary emissions from each 

potline using the methods in § 63.849, the owner or operator may 

perform semiannual monitoring of TF, POM or PM secondary 

emissions from one potline using the test methods in § 63.849(a) 

or (b) to represent the performance of similar potline(s). The 

similar potline(s) must be monitored using an alternative method 

that meets the requirements of (d)(1) through (d)(7) of this 

section. Two or more potlines are similar if the owner or 

operator demonstrates that their structure, operability, type of 

emissions, volume of emissions and concentration of emissions 

are substantially equivalent. 

(1) To demonstrate (to the satisfaction of the regulatory 

authority) that the level of emission control performance is the 
63 

same or better, the owner or operator shall perform an emission 

test using an alternative monitoring procedure for the similar 

potline simultaneously with an emission test using the 

applicable test methods. The results of the emission test using 

the applicable test methods must be in compliance with the 

applicable emission limit for existing or new potlines in 

§63.843 or §63.844. An alternative method: 

(i) For TF emissions, must account for or include gaseous 

fluoride and cannot be based on measurement of particulate 

matter or particulate fluoride alone; and 

(ii) For TF, and POM and PM emissions, must meet or exceed 

Method 14 criteria. 

(2) An HF continuous emission monitoring system is an 

approved alternative for the monitoring of TF secondary 

emissions. 

(3) An owner or operator electing to use an alternative 

monitoring procedure shall establish an alternative emission 

limit based on at least nine simultaneous runs using the 

applicable test methods and the alternative monitoring method. 

All runs must represent a full process cycle. 

(4) The owner or operator shall derive an alternative 

emission limit for the HF continuous emission monitor or an 

alternative method using either of the following procedures: 
64 

(i) Use the highest value from the alternative method 

associated with a simultaneous run by the applicable test method 

that does not exceed the applicable emission limit; or 

(ii) Correlate the results of the two methods (the 

applicable test method results and the alternative monitoring 

method results) and establish an emission limit for the 

alternative monitoring system that corresponds to the applicable 

emission limit. 

(5) The owner or operator shall submit the results required 

in paragraph (d)(4) of this section and all supporting 

documentation to the applicable regulatory authority for review 

and approval. 

(6) The regulatory authority shall review and approve or 

disapprove the request for an alternative method and alternative 

emission limit. The criterion for approval shall be a 

demonstration (to the satisfaction of the regulatory authority) 

that the alternative method and alternative emission limit 

achieve a level of emission control that is the same as or 

better than the level that would have otherwise been achieved by 

the applicable method and emission limit. 

(7) If the alternative method is approved by the applicable 

regulatory authority, the owner or operator shall perform 

monthly semiannual emission monitoring using the approved 
65 

alternative monitoring procedure to demonstrate compliance with 

the alternative emission limit for each similar potline. 

(e) Reduced sampling frequency. The owner or operator may 

submit a written request to the applicable regulatory authority 

to establish an alternative testing requirement to reduce the 

sampling of secondary TF emissions from potlines from monthly to 

quarterly. 

(1) In the request, the owner or operator shall provide 

information and data demonstrating, to the satisfaction of the 

applicable regulatory authority, that secondary emissions of TF 

from potlines have low variability during normal operations 

using the procedures in paragraphs (e)(1)(i) or (e)(1)(ii) of 

this section. 

(i) Submit data from 24 consecutive months of sampling that 

show the average TF emissions are less than 60 percent of the 

applicable limit and that no monthly performance test in the 24 

months of sampling exceeds 75 percent of the applicable limit; 

or 

(ii) Submit data and a statistical analysis that the 

regulatory authority may evaluate based on the approach used in 

“Primary Aluminum: Statistical Analysis of Potline Fluoride 

Emissions and Alternative Sampling Frequency” (EPA–450–86–012, 

October 1986), which is available from the National Technical 
66 

Information Service (NTIS), 5285 Port Royal Road, Springfield, 

VA 22161. 

(2) An approved alternative requirement must include a test 

schedule and the method to be used to measure emissions for 

performance tests. 

(3) The owner or operator of a plant that has received 

approval of an alternative sampling frequency under §60.194 of 

this chapter is deemed to have approval of the alternative 

sampling frequency under this subpart. 

(4) If emissions in excess of the applicable TF limit occur 

while performing quarterly sampling approved under paragraph 

(e)(1)(i) of this section, the owner or operator shall return to 

monthly sampling for at least 12 months and may reduce to 

quarterly sampling when: 

(i) The average of all tests performed over the most recent 

24-month period does not exceed 60 percent of the applicable 

limit, and 

(ii) No more than one monthly performance test in the most 

recent 24-month period exceeds 75 percent of the applicable 

limit. 

(5) If emissions in excess of the applicable TF limit occur 

while performing quarterly sampling approved under paragraph 

(e)(1)(ii) of this section, the owner or operator shall 

immediately return to the monthly sampling schedule required by 
67 

paragraph (a) of this section until another request for an 

alternative sampling frequency is approved by the applicable 

regulatory authority.[Reserved]

(f) Monitoring parameters for emission control devices. The 

owner or operator shall install, operate, calibrate, and 

maintain a continuous parameter monitoring system for each 

emission control device. The owner or operator shall submit for 

approval by the regulatory authority a description of the 

parameter(s) to be monitored, the operating limits, and the 

monitoring frequency to ensure that the control device is being 

properly operated and maintained. An explanation of the criteria 

used for selection of the parameter(s), the operating limits, 

and the monitoring frequency, including how these relate to 

emission control also shall be submitted to the regulatory 

authority. Except as provided in paragraph (l) of this section, 

the following monitoring devices shall be installed: 

(1) For dry alumina scrubbers, devices for the measurement 

of alumina flow and air flow; 

(2) For dry coke scrubbers, devices for the measurement of 

coke flow and air flow; 

(3) For wet scrubbers as the primary control system, 

devices for the measurement of water flow and air flow; 

(4) For electrostatic precipitators, devices for the 

measurement of voltage and secondary current; and 
68 

(5) For wet roof scrubbers for secondary emission control: 

(i) A device for the measurement of total water flow; and 

(ii) The owner or operator shall inspect each control 

device at least once each operating day to ensure the control 

device is operating properly and record the results of each 

inspection.

(6) For emission sources control device exhaust streams for 

which the owner or operator chooses to demonstrate continuous 

compliance through bag leak detection systems you must install 

and operate a bag leak detection system according to the 

requirements in paragraph (o) of this section, and you must set 

your operating limit such that the sum of the durations of bag 

leak detection system alarms does not exceed 5 percent of the 

process operating time during a 6-month period. 

(7) For emission sources control device exhaust streams for 

which the owner or operator chooses to demonstrate continuous 

compliance through a PM CEMS, you must install and operate a PM 

CEMS according to the requirements in paragraph (p) of this 

section. You must determine continuous compliance averaged on a 

rolling 30 operating day basis, updated at the end of each new 

operating day. All valid hours of data from 30 successive 

operating days shall be included in the arithmetic average. 

Compliance is demonstrated when the 30 operating day PM 
69 

emissions are equal to or less than the applicable emission 

limits in § 63.843, § 63.844, or § 63.846.

(g) Visible emissions. The owner or operator shall visually 

inspect the exhaust stack(s) of each control device on a daily 

basis for evidence of any visible emissions indicating abnormal 

operation.The owner or operator of a new or reconstructed 

affected source that is subject to a PM limit shall comply with 

the requirements of either paragraph (f)(6) or (f)(7) of this 

section. The owner or operator of an existing affected source 

that is equipped with a control device and is subject to a PM 

limit shall: 

(1) Install and operate a bag leak detection system in 

accordance with paragraph (f)(6) of this section; or 

(2) Install and operate a PM CEMS in accordance with 

paragraph (f)(7) of this section; or 

(3) Visually inspect the exhaust stack(s) of each fabric 

filter using Method 22 on a twice daily basis (at least 4 hours 

apart) for evidence of any visible emissions indicating abnormal 

operations and, must initiate corrective actions within 1 hour 

of a visible emissions inspection that indicates abnormal 

operation. Corrective actions shall include, at a minimum, 

isolating, shutting down and conducting an internal inspection 

of the baghouse compartment that is the source of the visible 

emissions that indicate abnormal operations.
70 

(h) Corrective action. If a monitoring device for a primary 

control device measures an operating parameter outside the 

limit(s) established pursuant to §63.847(h), if visible 

emissions indicating abnormal operation are observed from the 

exhaust stack of a control device during a daily inspection, or 

if a problem is detected during the daily inspection of a wet 

roof scrubber for potline secondary emission control, the owner 

or operator shall initiate corrective action procedures within 1 

hour. Failure to initiate the corrective action procedures 

within 1 hour or to take the necessary corrective actions to 

remedy the problem is a violation. 

(i) Exceedances. If the limit for a given operating 

parameter associated with monitoring a specific control device 

is exceeded six times in any semiannual reporting period, then 

any subsequent exceedance in that reporting period is a 

violation. For the purpose of determining the number of 

exceedances, no more than one exceedance shall be attributed in 

any given 24-hour period. 

(j) Weight of aluminum and green anodes. The owner or 

operator of a new or existing potline or anode bake furnace 

shall install, operate, and maintain a monitoring device to 

determine the daily weight of aluminum produced and the weight 

of green anode material placed in the anode bake furnace. The 

weight of green anode material may be determined by monitoring 
71 

the weight of all anodes or by monitoring the number of anodes 

placed in the furnace and determining an average weight from 

measurements of a representative sample of anodes. 

(k) Accuracy and calibration. The owner or operator shall 

submit recommended accuracy requirements to the regulatory 

authority for review and approval. All monitoring devices 

required by this section must be certified by the owner or 

operator to meet the accuracy requirements and must be 

calibrated in accordance with the manufacturer's instructions. 

(l) Alternative operating parameters. The owner or operator 

may monitor alternative control device operating parameters 

subject to prior written approval by the applicable regulatory 

authority. 

(m) Other control systems. An owner or operator using a 

control system not identified in this section shall request that 

the applicable regulatory authority include the recommended 

parameters for monitoring in the facility's part 70 permit.

(n) PM emissions from paste production plants. Using the 

procedures in § 63.847 and in the approved test plan, the owner 

or operator shall monitor PM emissions from each paste 

production plant on an annual basis. The owner or operator shall 

compute and record the annual average of PM emissions from at 

least three runs to determine compliance with the applicable 
72 

emission limits. The owner or operator must include all valid 

runs in the annual average. 

(o) Bag leak detection system. For each new affected source 

subject to a PM emissions limit, you must install, operate and 

maintain a bag leak detection system according to paragraphs 

(o)(1) through (3) of this section, unless a system meeting the 

requirements of paragraph (p) of this section, for a CEMS, is 

installed for monitoring the concentration of PM. 

(1) You must develop and implement written procedures for 

control device maintenance that include, at a minimum, a 

preventative maintenance schedule that is consistent with the 

control device manufacturer's instructions for routine and longterm maintenance. 

(2) Each bag leak detection system must meet the 

specifications and requirements in paragraphs (o)(2)(i) through 

(viii) of this section. 

(i) The bag leak detection system must be certified by the 

manufacturer to be capable of detecting PM emissions at 

concentrations of 1.0 milligram per dry standard cubic meter 

(0.00044 grains per actual cubic foot) or less. 

(ii) The bag leak detection system sensor must provide 

output of relative PM loadings. 
73 

(iii) The bag leak detection system must be equipped with 

an alarm system that will alarm when an increase in relative 

particulate loadings is detected over a preset level. 

(iv) You must install, calibrate, operate and maintain the 

bag leak detection system according to the manufacturer's 

written specifications and recommendations. 

(v) The initial adjustment of the system must, at a 

minimum, consist of establishing the baseline output by 

adjusting the sensitivity (range) and the averaging period of 

the device and establishing the alarm set points and the alarm 

delay time. 

(vi) Following initial adjustment, you must not adjust the 

sensitivity or range, averaging period, alarm set points, or 

alarm delay time, except in accordance with the procedures 

developed under paragraph (o)(1) of this section. You cannot 

increase the sensitivity by more than 100 percent or decrease 

the sensitivity by more than 50 percent over a 365-day period 

unless such adjustment follows a complete PM control device 

inspection that demonstrates that the PM control device is in 

good operating condition. 

(vii) You must install the bag leak detector downstream of 

the PM control device. 
74 

(viii) Where multiple detectors are required, the system's 

instrumentation and alarm may be shared among detectors. 

(3) You must include in the written procedures required by 

paragraph (o)(1) of this section a corrective action plan that 

specifies the procedures to be followed in the case of a bag 

leak detection system alarm. The corrective action plan must 

include, at a minimum, the procedures that you will use to 

determine and record the time and cause of the alarm as well as 

the corrective actions taken to minimize emissions as specified 

in paragraphs (o)(3)(i) and (ii) of this section. 

(i) The procedures used to determine the cause of the alarm 

must be initiated within 1 hour of the alarm. 

(ii) The cause of the alarm must be alleviated by taking 

the necessary corrective action(s) that may include, but not be 

limited to, those listed in paragraphs (o)(3)(ii)(A) through (F) 

of this section. 

(A) Inspecting the PM control device for air leaks, torn or 

broken filter elements, or any other malfunction that may cause 

an increase in emissions. 

(B) Sealing off defective bags or filter media. 

(C) Replacing defective bags or filter media, or otherwise 

repairing the control device. 

(D) Sealing off a defective baghouse compartment. 
75 

(E) Cleaning the bag leak detection system probe, or 

otherwise repairing the bag leak detection system. 

(F) Shutting down the process producing the particulate 

emissions. 

(p) Particulate Matter CEMS. If you are using a CEMS to 

measure particulate matter emissions to meet requirements of 

this subpart, you must install, certify, operate and maintain 

the particulate matter CEMS as specified in paragraphs (p)(1) 

through (4) of this section. 

(1) You must conduct a performance evaluation of the PM 

CEMS according to the applicable requirements of § 60.13, and 

Performance Specification 11 at 40 CFR part 60, Appendix B of 

this chapter. 

(2) During each PM correlation testing run of the CEMS 

required by Performance Specification 11 at 40 CFR part 60, 

Appendix B of this chapter, collect data concurrently by both 

the CEMS and by conducting performance tests using Method 5, 5D 

or 5I at 40 CFR part 60, Appendix A–3. 

(3) Operate and maintain the CEMS in accordance with 

Procedure 2 at 40 CFR part 60, Appendix F of this chapter. 

Relative Response Audits must be performed annually and Response 

Correlation Audits must be performed every three years. 

§ 63.849 Test methods and procedures. 
76 

(a) The owner or operator shall use the following reference 

methods to determine compliance with the applicable emission 

limits for TF, and POM emissionsPOM, PM, Ni, As, Hg, PCB and 

conduct visible emissions observations: 

(1) Method 1 in appendix A to part 60 of this chapter for 

sample and velocity traverses; 

(2) Method 2 in appendix A to part 60 of this chapter for 

velocity and volumetric flow rate; 

(3) Method 3 in appendix A to part 60 of this chapter for 

gas analysis; 

(4) Method 13A or Method 13B in appendix A to part 60 of 

this chapter, or an approved alternative, for the concentration 

of TF where stack or duct emissions are sampled; 

(5) Method 13A or Method 13B and Method 14 or Method 14A in 

appendix A to part 60 of this chapter or an approved alternative 

method for the concentration of TF where emissions are sampled 

from roof monitors not employing wet roof scrubbers; 

(6) Method 315 in appendix A to this part or an approved 

alternative method for the concentration of POM where stack or 

duct emissions are sampled; and 

(7) Method 315 in appendix A to this part and Method 14 or 

14A in appendix A to part 60 of this chapter or an approved 

alternative method for the concentration of POM where emissions 

are sampled from roof monitors not employing wet roof scrubbers.
77 

Method 315 need not be set up as required in the method. 

Instead, when using Method 14A, replace the Method 14A monitor 

cassette filter with the filter specified by Method 315. Recover 

and analyze the filter according to Method 315. When using 

Method 14, test at ambient conditions, do not heat the filter 

and probe, and do not analyze the back half of the sampling 

train; 

(8) Method 5 in appendix A to part 60 of this chapter or an 

approved alternative method for the concentration of PM where 

stack or duct emissions are sampled; 

(9) Method 17 and Method 14 or Method 14A in appendix A to 

part 60 of this chapter or an approved alternative method for 

the concentration of PM where emissions are sampled from roof 

monitors not employing wet roof scrubbers. Method 17 need not be 

set up as required in the method. Instead, when using Method 

14A, replace the Method 14A monitor cassette filter with the 

filter specified by Method 17. Recover and analyze the filter 

according to Method 17. When using Method 14, test at ambient 

conditions, do not heat the filter and probe, and do not analyze 

the back half of the sampling train; 

(10) Method 29 in appendix A to part 60 of this chapter or 

an approved alternative method for the concentration of mercury, 

nickel and arsenic where stack or duct emissions are sampled; 
78 

(11) Method 29 and Method 14 or Method 14A in appendix A to 

part 60 of this chapter or an approved alternative method for 

the concentration of nickel and arsenic where emissions are 

sampled from roof monitors not employing wet roof scrubbers. 

Method 29 need not be set up as required in the method. Instead, 

replace the Method 14A monitor cassette filter with the filter 

specified by Method 29. Recover and analyze the filter according 

to Method 29. When using Method 14, test at ambient conditions, 

do not heat the filter and probe, and do not analyze the back 

half of the sampling train; 

(12) Method 22 in Appendix A to part 60 of this chapter or 

an approved alternative method for determination of visual 

emissions; 

(13) Method 428 of the California Air Resources Board 

(incorporated by reference; see § 63.14) for the measurement of 

PCB where stack or duct emissions are sampled; and 

(14) Method 428 of the California Air Resources Board 

(incorporated by reference; see § 63.14) and Method 14 or Method 

14A in appendix A to part 60 of this chapter or an approved 

alternative method for the concentration of PCB where emissions 

are sampled from roof monitors not employing wet roof scrubbers.

(b) The owner or operator of a VSS potline or a SWPB 

potline equipped with wet roof scrubbers for the control of 

secondary emissions shall use methods that meet the intent of 
79 

the sampling requirements of Method 14 in appendix A to part 60 

of this chapter and that are approved by the State. Sample 

analysis shall be performed using Method 13A or Method 13B in 

appendix A to part 60 of this chapter for TF, Method 315 in 

appendix A to this part for POM, or an approved alternative 

method. 

(c) Except as provided in §63.845(g)(1), references to 

“potroom” or “potroom group” in Method 14 in appendix A to part 

60 of this chapter shall be interpreted as “potline” for the 

purposes of this subpart. 

(d) For sampling using Method 14 in appendix A to part 60 

of this chapter, the owner or operator shall install one Method 

14 manifold per potline in a potroom that is representative of 

the entire potline, and this manifold shall meet the 

installation requirements specified in section 2.2.1 of Method 

14 in appendix A to part 60 of this chapter. 

(e) The owner or operator may use an alternative test 

method for TF or POM emissions providing: 

(1) The owner or operator has already demonstrated the 

equivalency of the alternative method for a specific plant and 

has received previous approval from the Administrator or the 

applicable regulatory authority for TF or POM measurements using 

the alternative method; or 
80 

(2) The owner or operator demonstrates to the satisfaction 

of the applicable regulatory authority that the results from the 

alternative method meet the criteria specified in §§63.848(d)(1) 

and (d)(3) through (d)(6). The results from the alternative 

method shall be based on simultaneous sampling using the 

alternative method and the following reference methods: 

(i) For TF, Methods 13 and 14 or Method 14A in appendix A 

to part 60 of this chapter; or 

(ii) For POM, Method 315 in appendix A to this part and 

Method 14 in appendix A to part 60 of this chapter.

(f) The owner or operator must use either ASTM D4239-14e1 

or ASTM D6376-10 (incorporated by reference; see § 63.14) for 

determination of the sulfur content in anode coke shipments to 

determine compliance with the applicable emission limit for COS 

emissions.

§ 63.850 Notification, reporting, and recordkeeping 

requirements. 

(a) Notifications. The owner or operator shall submit the 

following written notifications: 

(1) Notification for an area source that subsequently 

increases its emissions such that the source is a major source 

subject to the standard; 
81 

(2) Notification that a source is subject to the standard, 

where the initial startup is before the effective date of the 

standard; 

(3) Notification that a source is subject to the standard, 

where the source is new or has been reconstructed, the initial 

startup is after the effective date of the standard, and for 

which an application for approval of construction or 

reconstruction is not required; 

(4) Notification of intention to construct a new major 

source or reconstruct a major source; of the date construction 

or reconstruction commenced; of the anticipated date of startup; 

of the actual date of startup, where the initial startup of a 

new or reconstructed source occurs after the effective date of 

the standard, and for which an application for approval of 

construction or reconstruction is required [see §§63.9(b)(4) and 

(b)(5)]; 

(5) Notification of initial performance test; 

(6) Notification of initial compliance status; 

(7) One-time notification for each affected source of the 

intent to use an HF continuous emission monitor; 

(8) Notification of compliance approach. The owner or 

operator shall develop and submit to the applicable regulatory 

authority, if requested, an engineering plan that describes the 

techniques that will be used to address the capture efficiency 
82 

of the reduction cells for gaseous hazardous air pollutants in 

compliance with the emission limits in §§63.843, 63.844, and 

63.846; and 

(9) One-time notification of startup of an existing potline 

or potroom group, anode bake furnace, or paste production plant 

that was shut down for a long period and subsequently restarted. 

The owner or operator must provide written notice to the 

Administrator at least 30 days before the startup. 

(b) Performance test reports. The owner or operator shall 

report the results of the initial performance test as part of 

the notification of compliance status required in paragraph 

(a)(6) of this section. Except as provided in paragraph (d) of 

this section, the owner or operator shall submit a summary of 

all subsequent performance tests to the applicable regulatory 

authority on an annual basis. Within 60 days after the date of 

completing each performance test (as defined in § 63.2) required 

by this subpart, you must submit the results of the performance 

tests following the procedure specified in either paragraph 

(b)(1) or (b)(2) of this section. 

(1) For data collected using test methods supported by the 

EPA’s Electronic Reporting Tool (ERT) as listed on the EPA’s ERT 

Web site (http://www.epa.gov/ttn/chief/ert/index.html) at the 

time of the test, you must submit the results of the performance 

test to the EPA via the Compliance and Emissions Data Reporting 
83 

Interface (CEDRI). CEDRI can be accessed through the EPA’s 

Central Data Exchange (CDX) (https://cdx.epa.gov/epa_home.asp). 

Performance test data must be submitted in a file format 

generated through the use of the EPA’s ERT. Alternatively, you 

may submit performance test data in an electronic file format 

consistent with the extensible markup language (XML) schema 

listed on the EPA’s ERT Web site once the XML schema is 

available. If you claim that some of the performance test 

information being submitted is confidential business information 

(CBI), you must submit a complete file generated through the use 

of the EPA’s ERT or an alternate electronic file consistent with 

the XML schema listed on the EPA’s ERT Web site, including 

information claimed to be CBI, on a compact disc, flash drive, 

or other commonly used electronic storage media to the EPA. The 

electronic media must be clearly marked as CBI and mailed to 

U.S. EPA/OAQPS/CORE CBI Office, Attention: Group Leader, 

Measurement Policy Group, MD C404-02, 4930 Old Page Rd., Durham, 

NC 27703. The same ERT or alternate file with the CBI omitted 

must be submitted to the EPA via the EPA’s CDX as described 

earlier in this paragraph. 

(2) For data collected using test methods that are not 

supported by the EPA’s ERT as listed on the EPA’s ERT Web site 

at the time of the test, you must submit the results of the 
84 

performance test to the Administrator at the appropriate address 

listed in § 63.13. 

(3) For data collected which requires summation of results 

from both ERT and non-ERT supported test methods in order to 

demonstrate compliance with an emission limit, you must submit 

the results of the performance test(s) used to demonstrate 

compliance with that emission limit to the Administrator at the 

appropriate address listed in § 63.13.

(c) Startup, shutdown, and malfunction plan and reports. 

The owner or operator shall develop a written plan as described 

in §63.6(e)(3) that contains specific procedures to be followed 

for operating the source and maintaining the source during 

periods of startup, shutdown, and malfunction and a program of 

corrective action for malfunctioning process and control systems 

used to comply with the standards. The plan does not have to be 

submitted with the permit appplication or included in the 

operating permit. The permitting authority may review the plan 

upon request. In addition to the information required in 

§63.6(e)(3), the plan shall include: 

(1) Procedures, including corrective actions, to be 

followed if a monitoring device measures an operating parameter 

outside the limit(s) established under §63.847(h), if visible 

emissions from an exhaust stack indicating abnormal operation of 

a control device are observed by the owner or operator during 
85 

the daily inspection required in §63.848(g), or if a problem is 

detected during the daily inspection of a wet roof scrubber for 

potline secondary emission control required in 

§63.848(f)(5)(ii); and 

(2) The owner or operator shall also keep records of each 

event as required by §63.10(b) and record and report if an 

action taken during a startup, shutdown, or malfunction is not 

consistent with the procedures in the plan as described in 

§63.6(e)(3)(iv). 

(c) Performance evaluation reports. Within 60 days after 

the date of completing each continuous emissions monitoring 

system performance evaluation (as defined in § 63.2), you must 

submit the results of the performance evaluation following the 

procedure specified in either paragraph (c)(1) or (c)(2) of this 

section. 

(1) For performance evaluations of continuous monitoring 

systems measuring relative accuracy test audit (RATA) pollutants 

that are supported by the EPA’s ERT as listed on the EPA’s ERT 

Web site at the time of the test, you must submit the results of 

the performance evaluation to the EPA via the CEDRI. (CEDRI can 

be accessed through the EPA’s CDX.) Performance evaluation data 

must be submitted in a file format generated through the use of 

the EPA’s ERT. Alternatively, you may submit performance 

evaluation data in an electronic file format consistent with the 
86 

XML schema listed on the EPA’s ERT Web site once the XML schema 

is available. If you claim that some of the performance 

evaluation information being transmitted is CBI, you must submit 

a complete file generated through the use of the EPA’s ERT or an 

alternate electronic file consistent with the XML schema listed 

on the EPA’s ERT Web site, including information claimed to be 

CBI, on a compact disc, flash drive, or other commonly used 

electronic storage media to the EPA. The electronic storage 

media must be clearly marked as CBI and mailed to U.S. 

EPA/OAQPS/CORE CBI Office, Attention: Group Leader, Measurement 

Policy Group, MD C404-02, 4930 Old Page Rd., Durham, NC 27703. 

The same ERT or alternate file with the CBI omitted must be 

submitted to the EPA via the EPA’s CDX as described earlier in 

this paragraph. 

(2) For any performance evaluations of continuous 

monitoring systems measuring RATA pollutants that are not 

supported by the EPA’s ERT as listed on the EPA’s ERT Web site 

at the time of the test, you must submit the results of the 

performance evaluation to the Administrator at the appropriate 

address listed in § 63.13.

(d) Excess emissions report. As required by §63.10(e)(3), 

the owner or operator shall submit a report (or a summary 

report) if measured emissions are in excess of the applicable 

standard. The report shall contain the information specified in 
87 

§63.10(e)(3)(v) and be submitted semiannually unless quarterly 

reports are required as a result of excess emissions. 

(d) Reporting. In addition to the information required 

under § 63.10 of the General Provisions, the owner or operator 

must provide semiannual reports containing the information 

specified in paragraphs (d)(1) and (2) of this section to the 

Administrator or designated authority. 

(1) Excess emissions report. As required by § 63.10(e)(3), 

the owner or operator must submit a report (or a summary report) 

if measured emissions are in excess of the applicable standard. 

The report must contain the information specified in 

§ 63.10(e)(3)(v) and be submitted semiannually unless quarterly 

reports are required as a result of excess emissions. 

(2) If there was a malfunction during the reporting period, 

the owner or operator must submit a report that includes the 

number, duration and a brief description for each type of 

malfunction which occurred during the reporting period and which 

caused or may have caused any applicable emission limitation to 

be exceeded. The report must also include a description of 

actions taken by an owner or operator during a malfunction of an 

affected source to minimize emissions in accordance with 

§§ 63.843(f) and 63.844(f), including actions taken to correct a 

malfunction.
88 

(e) Recordkeeping. The owner or operator shall maintain 

files of all information (including all reports and 

notifications) required by §63.10(b) and by this subpart. 

(1) The owner or operator must retain each record for at 

least 5 years following the date of each occurrence, 

measurement, maintenance, corrective action, report, or record. 

The most recent 2 years of records must be retained at the 

facility. The remaining 3 years of records may be retained 

offsite; 

(2) The owner or operator may retain records on microfilm, 

on a computer, on computer disks, on magnetic tape, or on 

microfiche; 

(3) The owner or operator may report required information 

on paper or on a labeled computer disc using commonly available 

and compatible computer software; and 

(4) In addition to the general records required by 

§63.10(b), the owner or operator shall maintain records of the 

following information: 

(i) Daily production rate of aluminum; 

(ii) Daily production rate of green anode material placed 

in the anode bake furnace; 

(iii) A copy of the startup, shutdown, and malfunction 

plan;[Reserved]
89 

(iv) Records of design information for paste production 

plant capture systems; 

(v) Records of design information for an alternative 

emission control device for a paste production plant; 

(vi) Records supporting the monitoring of similar potlines 

demonstrating that the performance of similar potlines is the 

same as or better than that of potlines sampled by manual 

methods; 

(vii) Records supporting a request for reduced sampling of 

potlines; 

(viii) Records supporting the correlation of emissions 

measured by a continuous emission monitoring system to emissions 

measured by manual methods and the derivation of the alternative 

emission limit derived from the measurements; 

(ix) The current implementation plan for emission averaging 

and any subsequent amendments; 

(x) Records, such as a checklist or the equivalent, 

demonstrating that the daily inspection of a potline with wet 

roof scrubbers for secondary emission control has been performed 

as required in §63.848(f)(5)(ii), including the results of each 

inspection; 

(xi) Records, such as a checklist or the equivalent, 

demonstrating that the daily visual inspection of the exhaust 
90 

stack for each control device has been performed as required in 

§63.848(g), including the results of each inspection; 

(xii) For a potline equipped with an HF continuous emission 

monitor, records of information and data required by §63.10(c); 

(xiii) Records documenting the corrective actions taken 

when the limit(s) for an operating parameter established under 

§63.847(h) were exceeded, when visible emissions indicating 

abnormal operation were observed from a control device stack 

during a daily inspection required under §63.848(g), or when a 

problem was detected during the daily inspection of a wet roof 

scrubber for potline secondary control required in 

§63.848(f)(5)(ii); 

(xiv) Records documenting any POM data that are invalidated 

due to the installation and startup of a cathode; and

(xv) Records documenting the portion of TF that is measured 

as particulate matter and the portion that is measured as 

gaseous when the particulate and gaseous fractions are 

quantified separately using an approved test method.; 

(xvi) Records of the occurrence and duration of each 

malfunction of operation (i.e., process equipment) or the air 

pollution control equipment and monitoring equipment; and 

(xvii) Records of actions taken during periods of 

malfunction to minimize emissions in accordance with 

§§ 63.843(f) and 63.844(f), including corrective actions to 
91 

restore malfunctioning process and air pollution control and 

monitoring equipment to its normal or usual manner of operation. 

(f) All reports required by this subpart not subject to the 

requirements in paragraph (b) or (c) of this section must be 

sent to the Administrator at the appropriate address listed in 

§ 63.13. If acceptable to both the Administrator and the owner 

or operator of a source, these reports may be submitted on 

electronic media. The Administrator retains the right to require 

submittal of reports subject to paragraph (b) of this section in 

paper format.

§ 63.851 Regulatory authority review procedures. 

(a) The applicable regulatory authority shall notify the 

owner or operator in writing of the need for additional time to 

review the submissions in paragraphs (a)(1) through (a)(5) of 

this section or of approval or intent to deny approval of the 

submissions in paragraphs (a)(1) through (a)(5) of this section 

within 60 calendar days after receipt of sufficient information 

to evaluate the submission. The 60-day period begins after the 

owner or operator has been notified that the submission is 

complete. 

(1) The test plan in §63.847(b); 

(2) Request to change limits for operating parameters in 

§63.847(h)(3); 
92 

(3) Request for similar potline monitoring in 

§63.848(d)(5); 

(4) Request for reduced sampling frequency in §63.848(e); 

and 

(5) Request for an alternative method in §63.849(e)(2). 

(b) The applicable regulatory authority shall notify the 

owner or operator in writing whether the submission is complete 

within 30 calendar days of receipt of the original submission or 

within 30 days of receipt of any supplementary information that 

is submitted. When a submission is incomplete, the applicable 

regulatory authority shall specify the information needed to 

complete the submission and shall give the owner or operator 30 

calendar days after receipt of the notification to provide the 

information. 

§ 63.852 Applicability of general provisions. 

The requirements of the general provisions in subpart A of 

this part that are not applicable to the owner or operator 

subject to the requirements of this subpart are shown in 

appendix A of this subpart. 

§ 63.853 Implementation and enforcement. 

(a) This subpart can be implemented and enforced by the 

U.S. EPA, or a delegated authority such as the applicable State, 

local, or Tribal agency. If the U.S. EPA Administrator has 

delegated authority to a State, local, or Tribal agency, then 
93 

that agency, in addition to the U.S. EPA, has the authority to 

implement and enforce this regulation. Contact the applicable 

U.S. EPA Regional Office to find out if this subpart is 

delegated to a State, local, or Tribal agency. 

(b) In delegating implementation and enforcement authority 

of this subpart to a State, local, or Tribal agency under 

subpart E of this part, the authorities contained in paragraph 

(c) of this section are retained by the Administrator of U.S. 

EPA and cannot be transferred to the State, local, or Tribal 

agency. 

(c) The authorities that cannot be delegated to State, 

local, or Tribal agencies are as specified in paragraphs (c)(1) 

through (4) of this section. 

(1) Approval of alternatives to the requirements in 

§§63.840, 63.843 (with the exception of 63.843(b)(3)), 63.844, 

63.845(a) introductory text, (a)(1), (b) through (e), (h), 

63.846(a) through (c), and 63.847(a)(1) and (4). 

(2) Approval of major alternatives to test methods under 

§63.7(e)(2)(ii) and (f), as defined in §63.90, and as required 

in this subpart. 

(3) Approval of major alternatives to monitoring under 

§63.8(f), as defined in §63.90, and as required in this subpart. 
94 

(4) Approval of major alternatives to recordkeeping and 

reporting under §63.10(f), as defined in §63.90, and as required 

in this subpart.

§ 63.854 Work Practice Standards for Potlines. 

(a) Periods of operation other than startup. If you own or 

operate a new or existing primary aluminum reduction affected 

source, you must comply with the requirements of paragraphs 

(a)(1) through (4) of this section during periods of operation 

other than startup. 

(1) Ensure the potline scrubbers and exhaust fans are 

operational at all times. 

(2) Ensure that the primary capture and control system is 

operating at all times. 

(3) Hood covers should be replaced as soon as possible 

after each potroom operation. 

(4) Inspect potlines daily and perform the work practices 

specified in paragraphs (a)(4)(i) through (iii) of this section. 

(i) Identify unstable pots as soon as practicable but in no 

case more than 12 hours from the time the pot became unstable; 

(ii) Reduce cell temperatures to as low as practicable, and 

follow the written operating plan described in paragraph (b)(4) 

of this section if the cell temperature exceeds the specified 

high temperature limit; and 
95 

(iii) Reseal pot crusts that have been broken as often and 

as soon as practicable. 

(5) Ensure that hood covers fit properly and are in good 

condition. 

(6) If the exhaust system is equipped with an adjustable 

damper system, the hood exhaust rate for individual pots must be 

increased whenever hood covers are removed from a pot, provided 

that the exhaust system will not be overloaded by placing too 

many pots on high exhaust. 

(7) Dust entrainment must be minimized during material 

handling operations and sweeping of the working aisles. 

(8) Only tapping crucibles with functional aspirator air 

return systems (for returning gases under the collection 

hooding) can be used, unless the regulatory authority approves 

an alternative tapping crucible. 

(b) Periods of startup. If you own or operate a new or 

existing primary aluminum reduction affected source, you must 

comply with the requirements of paragraphs (a)(1) through (4) 

and (b)(1) through (4) of this section during periods of startup 

for each affected potline. 

(1) Develop a potline startup schedule before starting up 

the potline. 

(2) Keep records of the number of pots started each day. 
96 

(3) Inspect potlines daily and adjust pot parameters to 

their optimum levels, as specified in the operating plan 

described in paragraph (b)(4) of this section, including, but 

not limited to: alumina addition rate, exhaust air flow rate, 

cell voltage, feeding level, anode current and liquid and solid 

bath levels. 

(4) Prepare a written operating plan to minimize emissions 

during startup to include, but not limited to, the requirements 

in (b)(1) through (3) of this section. The operating plan must 

include a specified high temperature limit for pots that will 

trigger corrective action. 

§ 63.855 Alternative Emissions Limits for Co-controlled New and 

Existing Anode Bake Furnaces.

(a) Applicability. The owner or operator of a new anode 

bake furnace meeting the criteria of paragraphs (a)(1) and (2) 

of this section may demonstrate compliance with alternative TF 

and POM emission limits according to the procedures of this 

section. 

(1) The new anode bake furnace must have been permitted to 

operate prior to May 1, 1998; and 

(2) The new anode bake furnace must share a common control 

device with one or more existing anode bake furnaces. 
97 

(b) TF emission limit. (1) Prior to the date on which each 

TF emission test is required to be conducted, the owner or 

operator must determine the applicable TF emission limit using 

Equation 6-A, 

       LTFC  LTFE  PE   PN PE  PN 0.018 / Eq. 6-A

Where: 

LTFC = Combined emission limit for TF, lb/ton green anode 

material placed in the bake furnace; 

LTFE = TF limit for emission averaging for the total number of 

new and existing anode bake furnaces from Table 4 to this 

subpart; 

PE = Mass of green anode placed in existing anode bake furnaces 

in the twelve months preceding the compliance test, ton/year; 

and 

PN = Mass of green anode placed in new anode bake furnaces in the 

twelve months preceding the compliance test, ton/year. 

(2) The owner or operator of a new anode bake furnace that 

is controlled by a control device that also controls emissions 

of TF from one or more existing anode bake furnaces must not 

discharge, or cause to be discharged into the atmosphere, any 

emissions of TF in excess of the emission limits established in 

paragraph (b)(1) of this section. 

(c) POM emission limits. (1) Prior to the date on which 

each POM emission test is required to be conducted, the owner or 
98 

operator must determine the applicable POM emission limit using 

Equation 6-B, 

       L POMC   PE   PN PE  PN 0.17 0.045 / Eq. 6-B 

Where: 

LPOMC = Combined emission limit for POM, lb/ton green anode 

material placed in the bake furnace. 

(2) The owner or operator of a new anode bake furnace that 

is controlled by a control device that also controls emissions 

of POM from one or more existing anode bake furnaces must not 

discharge, or cause to be discharged into the atmosphere, any 

emissions of TF in excess of the emission limits established in 

paragraph (c)(1) of this section. 

§§ 63.854-63.859 [Reserved] 

Table 1 to Subpart LL of Part 63—Potline TF Limits for Emission 

Averaging 

Type 

Monthly TF limit (1b/ton)

[for given number of potlines] 

2 lines 3 lines 4 lines 5 lines 6 lines 7 lines 8 lines

CWPB1 1.7 1.6 1.5 1.5 1.4 1.4 1.4

CWPB2 2.9 2.8 2.7 2.7 2.6 2.6 2.6

CWPB3 2.3 2.2 2.2 2.1 2.1 2.1 2.1

VSS1 2 1.9 1.8 1.7 1.7 1.7 1.7
99 

VSS2 2.6 2.5 2.5 2.4 2.4 2.4 2.4

HSS 2.5 2.4 2.4 2.3 2.3 2.3 2.3

SWPB 1.4 1.3 1.3 1.2 1.2 1.2 1.2

Table 2 to Subpart LL of Part 63—Potline POM Limits for Emission 

Averaging 

Type 

Quarterly POM limit (lb/ton)

[for given number of potlines] 

2 lines 3 lines 4 lines 5 lines 6 lines 7 lines

8

line

s 

Table 1 to Subpart LL of Part 63—Potline TF Limits 

for Emission Averaging 

Type 

Semiannual TF limit (lb/ton)

[for given number of potlines]

2 

lines 

3 

lines 

4 

lines

5

lines

6

lines

7

lines

8

lines 

CWPB1 1.7 1.6 1.5 1.5 1.4 1.4 1.4 

CWPB2 2.9 2.8 2.7 2.7 2.6 2.6 2.6 

CWPB3 2.3 2.2 2.2 2.1 2.1 2.1 2.1 

SWPB 1.4 1.3 1.3 1.2 1.2 1.2 1.2 

VSS2 2.6 2.5 2.5 2.4 2.4 2.4 2.4 
100 

HSS 4.1 3.8 3.7 3.5 3.5 3.4 3.3

VSS1 2.1 2.0 1.9 1.9 1.8 1.8 1.8

VSS2 5.0 4.7 4.5 4.4 4.3 4.2 4.1

Table 2 to Subpart LL of Part 63—Potline POM Limits for 

Emission Averaging 

Type 

Semiannual POM limit (lb/ton)

[for given number of potlines]

2 

line

s 

3 lines 

4

line

s 

5 

lines 

6

line

s 

7 lines 

8 

line

s 

CWPB1 1 0.9 0.9 0.9 0.8 0.8 0.8 

CWPB2 11.6 11.2 10.8 10.8 10.4 10.4 10.4 

CWPB3 2.5 2.4 2.4 2.3 2.3 2.3 2.3 

SWPB 14.8 13.8 13.8 13.8 13.8 13.8 13.8 

VSS2 1.7 1.6 1.5 1.5 1.4 1.4 1.4 

Table 3 to Subpart LL of Part 63—Anode Bake Furnace Limits for 

Emission Averaging 

Number of furnaces 

Emission limit (lb/ton of anode)

TF POM

2 0.11 0.17
101 

3 0.090 0.17

4 0.077 0.17

5 0.070 0.17

Table 3 to Subpart LL of Part 63—Potline PM Limits for Emission 

Averaging 

Type 

Semiannual PM limit (lb/ton)

[for given number of potlines]

2 

lines 

3 

lines 

4

line

s 

5 lines 6 lines 

7 

line

s 

8 lines 

CWPB1 6.1 6.1 5.3 5.3 5.0 5.0 5.0

CWPB2 10.6 10.3 9.9 9.9 9.5 9.5 9.5

CWPB3 18.4 17.6 17.6 16.8 16.8 16.8 16.8

SWPB 4.3 3.9 3.9 3.7 3.7 3.7 3.7

VSS2 25 24.1 24.1 23.1 23.1 23.1 23.1

Table 4 to Subpart LL of Part 63—Anode Bake Furnace 

Limits for Emission Averaging 

Number of 

furnaces Emission limit (lb/ton of anode) 

TF POM PM

2 0.11 0.17 0.11 
102 

3 0.09 0.17 0.091 

4 0.077 0.17 0.076 

5 0.07 0.17 0.071 

Appendix A to Subpart LL of Part 63—Applicability of General 

Provisions 

General 

provisions 

citation Requirement 

Applies to 

subpart LL Comment 

63.1(c)(2) No All are major sources.

63.2 Definition 

of 

“reconstruction” 

 No Subpart LL defines 

“reconstruction.” 

63.6(c)(1) Compliance 

date for 

existing 

sources 

No Subpart LL specifies 

compliance date for 

existing sources. 

63.6(h) Opacity/VE 

standards 

Only in 

§63.845 

Opacity standards 

applicable only when 

incorporating the NSPS 

requirements under 

§63.845. 
103 

63.7(a)(2)(ii) 

and (iii) 

Performance 

testing 

requirements 

No Subpart LL specifies 

performance test 

dates. 

63.8(c)(4)–(c)(8) CMS operation 

and 

maintenance 

No Subpart LL does not 

require COMS/CMS or 

CMS performance 

specifications. 

63.8(d) Quality 

control 

No Subpart LL does not 

require CMS or CMS 

performance 

evaluation. 

63.8(e) Performance 

evaluation for 

CMS 

No 

63.9(b)(1)–(5) Initial 

notifications 

Yes, 

except as 

noted in 

“comment” 

column 

§63.850(a)(9) includes 

requirement for 

startup of an existing 

affected source that 

has been shut down. 

63.9(e) Notification 

of performance 

test 

No Subpart LL specifies 

notification of 

performance tests. 
104 

63.9(f) Notification 

of VE or 

opacity test 

Only in 

§63.845 

Notification is 

required only when 

incorporating the NSPS 

requirements under 

§63.845. 

63.9(g) Additional CMS 

notification 

No 

63.10(d)(2) Performance 

test reports 

No Subpart LL specifies 

performance test 

reporting. 

63.10(d)(3) Reporting 

VE/opacity 

observations 

Only in 

§63.845 

Reporting is required 

only when 

incorporating the NSPS 

requirements under 

§63.845. 

63.10(e)(2) Reporting 

performance 

evaluations 

No Subpart LL does not 

require performance 

evaluation for CMS. 

63.11(a)–(b) Control device 

requirements 

No Flares not applicable.

Appendix A to Subpart LL of Part 63—Applicability of General 

Provisions (40 CFR Part 63, Subpart A) 
105 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.1 (a)(1) 

through (4) 

General 

Applicability 

Yes 

63.1 (a)(5) No [Reserved]. 

63.1(a)(6) Yes 

63.1(a)(7) 

through (9) 

 No [Reserved]. 

63.1(a)(10) 

through (12) 

 Yes 

63.1(b)(1) 

through (3) 

Initial 

Applicability 

Determination 

Yes (b)(2) Reserved. 

63.1(c)(1) Applicability 

after standard 

Established 

Yes 

63.1(c)(2) Yes Area sources are 

not subject to 

this subpart. 

63.1(c)(3) and 

(4) 

 No [Reserved]. 

63.1(c)(5) Yes 
106 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.1(d) No [Reserved]. 

63.1(e) Applicability 

of Permit 

Program 

Yes 

63.2 Definitions Yes Reconstruction 

defined in 

§ 63.842. 

63.3 Units and 

Abbreviations 

Yes 

63.4(a)(1) and 

(2) 

Prohibited 

activities 

Yes 

63.4(a)(3) 

through (5) 

 No [Reserved]. 

63.4(b) and (c) Circumvention/S

everability 

Yes 

63.5(a) Construction/Re

construction 

Applicability 

Yes 
107 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.5(b)(1) Existing, New, 

Reconstructed 

Sources 

Requirements 

Yes 

63.5(b)(2) No [Reserved]. 

63.5(b)(3) and 

(4) 

 Yes 

63.5(b)(5) No [Reserved]. 

63.5(b)(6) Yes 

63.5(c) No [Reserved]. 

63.5(d) Application for 

Approval of 

Construction/Re

construction 

Yes 

63.5(e) Approval of 

Construction/Re

construction 

Yes 
108 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.5(f) Approval of 

Construction/Re

construction 

Based on State 

Review 

Yes 

63.6(a) Compliance with 

Standards and 

Maintenance 

Applicability 

Yes 

63.6(b)(1) 

through (5) 

New and 

Reconstructed 

Source Dates 

Yes See § 847(a)(6) 

and (7) 

63.6(b)(6) No [Reserved]. 

63.6(b)(7) Yes 

63.6(c)(1) Existing Source 

Dates 

No See § 847(a) 

63.6(c)(2) Yes 

63.6(c)(3) and 

(4) 

 No [Reserved]. 

63.6(c)(5) Yes 

63.6(d) No [Reserved]. 
109 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.6(e)(1)(i) No See §§ 63.843(f) 

and 63.844(f) for 

general duty 

requirement. 

63.6(e)(1)(ii) No 

63.6(e)(1)(iii) Yes 

63.6(e)(2) No [Reserved]. 

63.6(e)(3) Startup, 

Shutdown and 

Malfunction 

Plan 

No 

63.6(f)(1) Compliance with 

Emissions 

Standards 

No 

63.6(f) (2) Methods/Finding 

of Compliance 

Yes 

63.6(g) Alternative 

Standard 

Yes 
110 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.6(h) Compliance with 

Opacity/VE 

Standards 

Only in 

§ 63.845 

Opacity standards 

applicable only 

when 

incorporating the 

NSPS requirements 

under § 63.845 

63.6(i)(1) 

through (14) 

Extension of 

Compliance 

Yes 

63.6(i)(15) No [Reserved]. 

63.6(i)(16) Yes 

63.6(j) Exemption from 

Compliance 

Yes 

63.7(a) Performance 

Test 

Requirements 

Applicability 

Yes 

63.7(b) Notification Yes 

63.7(c) Quality 

Assurance/Test 

Plan 

Yes 
111 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.7(d) Testing 

facilities 

Yes 

63.7(e)(1) Conduct of 

Tests 

No See § 63.847(d) 

63.7(e)(2) 

through (4) 

 Yes 

63.7(f),(g), 

(h) 

Alternative 

Test Method 

Yes 

63.8(a)(1) and 

(2) 

Monitoring 

Requirements 

Applicability 

Yes 

63.8(a)(3) No [Reserved]. 

63.8(b) Conduct of 

Monitoring 

Yes 

63.8(c)(1)(i) No See §§ 63.843(f) 

and 63.844(f) for 

general duty 

requirement. 

63.8(c)(1)(ii) Yes 

63.8(c)(1)(iii) No 
112 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.8(c)(2) 

through (d)(2) 

 Yes 

63.8(d)(3) Yes, except 

for last 

sentence 

63.8(e) through 

(g) 

 Yes 

 

63.9(a) Notification 

Requirements 

Applicability 

Yes 

63.9(b) Initial 

Notifications 

Yes Notification of 

re-start 

specified in 

§ 63.850(a)(9) 

63.9(c) Request for 

Compliance 

Extension 

Yes 
113 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.9(d) New Source 

Notification 

for Special 

Compliance 

Requirements 

Yes 

63.9(e) Notification of 

Performance 

Test 

No 

63.9(f) Notification of 

VE/Opacity Test 

No 

63.9(g) Additional CMS 

Notifications 

No 

63.9(h)(1) 

through (3) 

Notification of 

Compliance 

Status 

Yes 

63.9(h)(4) No [Reserved]. 

63.9(h)(5) and 

(6) 

 Yes 

63.9(i) Adjustment of 

Deadlines 

Yes 
114 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.9(j) Change in 

Previous 

Information 

Yes 

63.10(a) Recordkeeping/R

eporting 

Applicability 

Yes 

63.10(b)(1) General 

Recordkeeping 

Requirements 

Yes 

63.10(b)(2)(i) No 

63.10(b)(2)(ii) No See 

§§ 63.850(e)(4)(x

vi) and (xvii) 

for recordkeeping 

of occurrence and 

duration of 

malfunctions and 

recordkeeping of 

actions taken 

during 

malfunction. 
115 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.10(b)(2)(iii

) 

 Yes 

63.10(b)(2)(iv) 

and (v) 

 No 

63.10(b)(2)(vi) 

through (xiv) 

 Yes 

63.(10)(b)(3) Yes 

63.10(c)(1) 

through (9) 

 Yes 

63.10(c)(10) 

and (11) 

 No See 

§§ 63.850(e)(4)(x

vi) and (xvii)for 

recordkeeping of 

malfunctions. 

63.10(c)(12) 

through (14) 

 Yes 

63.10(c)(15) No 

63.10(d)(1) General 

Reporting 

Requirements 

Yes 

63.10(d)(2) No See § 63.850(b) 
116 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.10(d)(3) and 

(4) 

 Yes 

63.10(d)(5) StartupShutdown and 

Malfunction 

Reports 

No See 

§ 63.850(d)(2) 

for reporting of 

malfunctions. 

63.10(e) and 

(f) 

Additional CMS 

Reports and 

Recordkeeping/ 

Reporting 

Waiver 

Yes 

63.11 Control 

Device/work 

practices 

requirements 

Applicability 

No 

63.12 State Authority 

and Delegations 

Yes 

63.13 Addresses Yes 

63.14 Incorporation 

by Reference 

Yes 
117 

Reference 

Section(s) ... 

Requirement Applies to 

subpart LL 

Comment

63.15 Information 

Availability 

/Confidentialit

y 

Yes 

63.16 Performance 

Track 

Provisions 

No