United States Environmental Protection Agency

General Permit for New or Modified Minor Sources of Air 

Pollution in Indian Country

http://www.epa.gov/air/tribal/tribalnsr.html

Background Document: General Air Quality Permit for New or Modified 

True Minor Source Boilers

Version 1.0

Last modified: July 2, 2014

1. Boilers Source Category Definition 

This permit covers steam generating units located at commercial facilities and industrial facilities which 

combust fossil fuels such as natural gas and petroleum liquids. A boiler is a device in which water 

typically is heated to provide steam to drive turbines or engines, supply heat, or process materials. This 

permit does not cover boilers located at electric utilities or boilers used for the burning of other fuels 

such as coal and wood. This source category does not cover the manufacturers of boilers. The proposed 

General Air Quality Permit for New or Modified True Minor Source Boilers only covers boilers that are 

located at true minor New Source Review (NSR) sources.

2. Source Category Characterization

The equipment and operation of fuel oil and natural gas boilers are described in AP 42, Fifth Edition, 

Volume I, Chapter 1: External Combustion Sources.1Information on fuel oil boilers and natural gas 

boilers is covered in Chapters 1.3 and 1.4, respectively.

Boilers designed to burn fuel oil primarily combust distillate oils and residual oils.

2 Distillate and residual 

oils are distinguished by grade numbers, with Nos. 1 and 2 being distillate oils; Nos. 5 and 6 (also known 

as Bunker C) being residual oils; and No. 4 being either distillate oil or a mixture of distillate and residual 

oils. Distillate oils, which are more volatile and less viscous than residual oils, have negligible nitrogen 

and ash contents and usually contain less than 0.3 percent sulfur (by weight). Distillate oils include 

kerosene and diesel fuels and are used mainly in domestic and small commercial applications. The 

heavier residual oils contain significant quantities of ash, nitrogen, and sulfur and are used in industrial 

and large commercial applications.

These boilers can be of watertube, firetube, cast iron, or tubeless design. Watertube boilers are used in 

a variety of applications ranging from supplying large amounts of process steam to providing space heat 

for industrial facilities. In a watertube boiler, combustion heat is transferred to water flowing through 

tubes which line the furnace walls and boiler passes. The tube surfaces in the furnace (which houses the 

burner flame) absorb heat primarily by radiation from the flames. The tube surfaces in the boiler

(adjacent to the primary furnace) absorb heat primarily by convective heat transfer. Firetube boilers are 

used primarily for heating systems, industrial process steam generators, and portable power boilers. In 

firetube boilers, the hot combustion gases flow through the tubes while the water being heated 

circulates outside of the tubes. A cast iron boiler is one in which combustion gases rise through a vertical 

heat exchanger and out through an exhaust duct. Water in the heat exchanger tubes is heated as it

 

1 AP-42, Fifth Edition, Volume I, Chapter 1: External Combustion Sources, 

http://www.epa.gov/ttn/chief/ap42/ch01/index.html.

2 AP-42, Chapter 1.3 – Fuel Oil Combustion, http://www.epa.gov/ttn/chief/ap42/ch01/index.html.
Page 2 of 21

moves upward through the tubes. Cast iron boilers produce low pressure steam or hot water, and 

generally burn oil or natural gas. They are used primarily in the residential and commercial sectors. 

Tubeless boilers incorporate nested pressure vessels with water in between the shells. Combustion 

gases are fired into the inner pressure vessel and are then sometimes recirculated outside the second 

vessel.

Natural gas combustion boilers are used to generate industrial electric power, produce industrial 

process steam and heat, and heat residential and commercial space.3 Natural gas is generally more than 

85 percent methane with varying amounts of ethane, propane, butane, and inert gases (typically 

nitrogen, carbon dioxide, and helium). Natural gas combustion boilers may be of watertube, firetube, or 

cast iron design. Watertube boilers can be distinguished either as field erected units or packaged units; 

the former are built onsite in either wall-fired or tangential-fired configurations and generally have heat 

input levels exceeding 100 million British thermal units (MMBtu)/hour (hr), while the latter are shipped 

where needed, are always wall-fired, and generally have heat input levels less than 100 MMBtu/ hr.

Liquefied petroleum gas (LPG) combustion boilers use processes similar to those of natural gas 

combustion. Liquid petroleum gas consists of propane, propylene, butane, and butylenes.4 The three 

grades of LPG used as heating fuels are commercial-grade propane, engine fuel-grade propane (also 

known as HD-5 propane), and commercial-grade butane. Commercial-grade propane and HD-5 propane 

typically have heating values of about 90,500 Btu/gallon, while commercial-grade butane’s heating value 

is 97,400 Btu/gallon. Liquefied petroleum gas is fired as a primary and backup fuel in small commercial 

and industrial boilers and space heating equipment and can be used to generate heat and process steam 

for industrial facilities and in most domestic appliances that typically use natural gas. Additional

information on LPG boilers can be found in Chapter 1.5 of AP-42.5

The emissions from fuel oil-fired boilers include particulate matter (PM), sulfur dioxide (SO2), nitrogen 

oxides (NOx), carbon monoxide (CO), small amounts of volatile organic compounds (VOC), and trace 

elements. The emissions from natural gas-fired and liquefied petroleum gas-fired boilers include NOx, 

CO, carbon dioxide, methane, nitrous oxide, VOCs, trace amounts of SO2, and PM.

3. State NSR Minor Source Permit Programs

The U.S. Environmental Protection Agency (EPA) researched state government websites for general 

permits for this source category and examined them for applicability to a permit for Indian country. The 

EPA selected the appropriate elements for the development of the documents and regulations in the 

general permit for this source category. The EPA identified the following states and local governments 

that have specific minor NSR programs (such as general permit or general order) for boilers: Arizona, 

Delaware, Indiana, Maryland, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, and Washington.

The requirements for the state permitting programs related to boilers not subject to New Source 

Performance Standard (NSPS) requirements are summarized in Table 9. Permits from these states were 

chosen for examination because of characteristics they possess:

 Readily available; 

 Clear throughput limits; and 

 

3 AP-42, Chapter 1.4 – Natural Gas Combustion, http://www.epa.gov/ttn/chief/ap42/ch01/index.html.

4 AP-42, Chapter 1.5 – Liquefied Petroleum Gas Combustion, 

http://www.epa.gov/ttn/chief/ap42/ch01/final/c01s05.pdf.

5

Ibid.
Page 3 of 21

 Organization of the regulations followed the typical form for federal NSR permits:

o Limitations and standards, and 

o Monitoring, testing, recordkeeping, and reporting requirements.

The state general permits and permits by rule for boilers vary from the streamlined (Indiana at four

pages) to the extremely detailed and complex (Arizona at 48 pages). 

The state boiler permits have either fuel input limits, heat input capacity limits, or limits on emissions. 

These vary by state. The assumptions and methodology for arriving at the fuel and heat input capacity 

limitations are not discussed in the permit application documents. The technical support documents 

used in developing the production limits, boiler/heater size, and engine displacement limits are not 

readily available for most states, with the exception of the Washington state general permit6for small 

boilers. The EPA assumes that each state is calculating the capacity limits and fuel input limits based on 

differences in the desired amount of air emissions. This is exemplified by the Oregon boiler permit,

7

which has two different particulate emission limits, one for attainment counties and one for PM10 nonattainment counties. Ohio issues seven different general permits for boilers,

8

ranging in capacity from 10 

MMBtu to 45 MMBtu.

All of the state boiler permits examined restrict issuance to true minor sources whose potential to emit 

(PTE) of criteria pollutants is less than 100 tons per year (tpy). These permits contain limits on fuel usage 

or boiler capacity/heater size, and the effect of the limits keeps emissions below the major source 

thresholds. The boiler permits also limit fuel sulfur content as a means to keep SO2 emissions below the 

major source thresholds. 

Visible emissions and opacity requirements are in all of the state permits, but they vary from state to 

state. Setbacks and stack height requirements are present in the Michigan9 and Washington10 state 

permits. Michigan requires that stacks be 50 feet from the property line and 150 feet from a residence, 

while Washington requires that boiler stacks be 100 feet from the property line. 

The Oregon and Arizona11 state boiler permits incorporate the requirements of NSPS Subpart Dc into the 

text of the permit. The Washington state boiler permit incorporates the requirements of Subpart Dc by 

reference. Oklahoma is unique in that it issues a general permit for true minor source facilities subject to 

an NSPS or National Emission Standards for Hazardous Air Pollutants. The requirements of 40 CFR 63, 

Subpart JJJJJJ are applicable to new and existing area source boilers that burn petroleum liquids, and are 

included in the Oklahoma permit.

12 Other state permits do not mention the federal requirements.

 

6 Washington Department of Ecology, Air Quality, Air Permits, General Orders of Approval, 

http://www.ecy.wa.gov/programs/air/AOP_Permits/Boiler/GeneralOrders.htm.

7 Oregon Department of Environmental Quality, Air Quality, General Air Contaminant Discharge Permits, 

http://www.deq.state.or.us/aq/permit/acdp/general.htm.

8 Ohio Environmental Protection Agency, General Permit Program, Boilers, 

http://www.epa.ohio.gov/dapc/genpermit/gensources.aspx#boilers.

9 Michigan Department of Environmental Quality, Air Quality Division, 

http://www.michigan.gov/documents/deq/deq-aqd-pti-boiler_applicability_spec_cond_356451_7.pdf.

10 Washington Department of Ecology, op. cit.

11 Arizona Department of Environmental Quality, General Permits, 

http://www.azdeq.gov/environ/air/permits/download/gnblrpermit.pdf.

12 Oklahoma Department of Environmental Quality, General Permits and Permits by Rule, 

http://www.deq.state.ok.us/aqdnew/permitting/genperm.htm.
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Table 9 in Section 5.2.3 contains a summary of the boiler permit requirements by state.

4. Requirements for General Permit

4.1 Documents for General Permit

The EPA developed a standardized set of permit documents in support of a general permit for boilers

located in Indian country. These consist of the following documents: 

 Questionnaire: Assists the facility owner or operator in determining whether they are eligible for 

a General Air Quality Permit;

 Request for Coverage under the General Air Quality Permit: States the criteria for qualification, 

gathers information on the source, facility location, and source contact, and requests technical 

information on facility equipment, capacity, and attainment status;

 Instructions: Guides the applicant in filling out the Request for Coverage under the General Air 

Quality Permit;

 General Air Quality Permit, Terms and Conditions: Contains the requirements and regulations 

with which the source must comply. The emission limitations, monitoring, recordkeeping and 

reporting requirements are in the permit, including requirements for sources located in 

nonattainment areas; and

 PTE Calculator Spreadsheet: Allows applicants to calculate their PTE, based on owner inputs of 

the specific equipment present at their source, assuming continuous operation throughout the 

year. The PTE Calculator spreadsheet generates potential emissions, based on these inputs. The 

spreadsheet illustrates the correlation between equipment capacity, type of fuel, and emissions.

4.2 Exemption and Qualification for General Permits

Facilities applying for the proposed general permit must meet the following criteria:

 Must be a true minor NSR source; 

 Must be minor source for hazardous air pollutants (HAPs); and

 Be below the maximum heat input capacity limitations established for the general permit.

New facilities with a PTE or modifications to existing facilities with an emissions increase lower than the 

minor NSR thresholds specified in Table 1 of the Indian Country Minor NSR rule (40 CFR 49.153) are 

exempt from the minor NSR program. The exemption thresholds for PM and criteria pollutants are listed 

in Table 1 below. Facilities applying for the proposed general permit will be required to calculate their 

PTE and may use the PTE calculator provided to determine if they are exempt from the minor NSR 

program. 

 
Page 5 of 21

 Table 1: Minor NSR Thresholds in 40 CFR 49.153

Pollutant Attainment Area Nonattainment Area

CO 10 tpy 5 tpy

PM 10 tpy 5 tpy

PM10 5 tpy 1 tpy

PM2.5 3 tpy 0.6 tpy

SO2 10 tpy 5 tpy

NOx 10 tpy 5 tpy

VOCs 5 tpy 2 tpy

Under current EPA policy, only true minor NSR sources qualify for the proposed general permit. 

Therefore, facilities will be required to compare their PTE to the NSR major source thresholds to 

determine if they qualify for the proposed general permit. The NSR major source threshold for 

attainment areas is 250 tpy for any criteria pollutant. The NSR major source thresholds for 

nonattainment areas are summarized in Table 2 below:

 Table 2: NSR Major Source Thresholds for Nonattainment Areas

Pollutant Nonattainment Classification NSR Major Source Threshold

Ozone

Marginal 100 tpy of VOC or NOX

Moderate 100 tpy of VOC or NOX

Serious 50 tpy of VOC or NOX

Severe 25 tpy of VOC or NOX

Extreme 10 tpy of VOC or NOX

PM10

Moderate 100 tpy

Serious 70 tpy

CO Moderate 100 tpy

Serious 50 tpy

SO2, NOx, PM2.5 No nonattainment classification 100 tpy

If the facility’s PTE is above the NSR major source threshold of 250 tpy, or above the applicable 

nonattainment area thresholds listed in Table 2 (for any pollutant), then the facility does not qualify for 

the proposed general permit. The following documents are available to assist sources in the screening 

and application process: 

 Questionnaire; and

 Request for Coverage under the General Air Quality Permit.

The questionnaire and the application for the boilers permit contain questions designed to limit the 

availability of this general permit to true minor source boilers. For facilities not exempt from the minor 

NSR program and having a PTE below the NSR major source thresholds, the facilities will further 

evaluate if they can meet the emission limitations established in this general permit. The specific 

requirements for the proposed general permit are discussed in Sections 4.3, 4.4, 4.5, and 4.6. Section 5 

provides background on the surrogate emissions limitations provided in the proposed boilers general 

permit.
Page 6 of 21

Facilities with HAP emissions at or above the major source thresholds are not eligible for a general 

permit under the minor NSR program. The major source thresholds for HAPs are 10 tpy for a single HAP 

and 25 tpy for any combination of HAPs. If, after construction or modification, a facility’s HAP emissions 

exceed the major source thresholds, the applicant will need to apply for a site-specific permit.

4.3 Specific Permit Requirements for General Permits

The terms and conditions of the proposed general permit were established according to the required 

permit content and analyses in the Indian Country Minor NSR rule. The required permit content is listed 

in 40 CFR 49.155(a) – What information must my permit include? Below we describe the basis for the 

permit conditions.

40 CFR 49.155(a)(1) – General Requirements

The rule establishes general requirements that each permit must identify: the effective date of the 

permit; the date by which the owner/operator must commence construction in order for the permit to 

remain valid; the emission units subject to the permit and their associated emission limitations; and 

monitoring, recordkeeping, and reporting requirements to assure compliance with the emission 

limitations. 

The proposed general permit contains all of this required information, except for the emission units 

subject to the permit. Because of the nature of general permits, it is more appropriate to identify the 

emission units covered by the general permit in the Approval of the Request for Coverage. The general 

permit incorporates the Approval of the Request for Coverage into the general permit. Each permit 

contains a separate section that specifically identifies the emission limitations and standards, monitoring 

and testing, recordkeeping, and reporting and notification requirements.

40 CFR 49.155(a)(2) – Emission Limitations

The permit must contain the emission limitations determined by the reviewing authority under 40 CFR 

49.154(c) for each affected emissions unit. In this general permit for boilers, limits on the maximum heat 

input capacity of the boilers are used to limit emissions of all criteria pollutants to below the NSR major 

source thresholds. Permit limits on concentrations of NOx and CO are also included, as these are the 

primary pollutants emitted by boilers. 40 CFR 49.154(c) – How will the reviewing authority determine the 

emission limitations that will be required in my permit? – identifies the case-by-case control technology 

review that must be used by the reviewing authority to determine the appropriate level of control. In 

carrying out the case-by-case control technology review, the reviewing authority must consider the 

following factors:

1. Local air quality conditions;

2. Typical control technology or other emission reduction measures used by similar sources in 

surrounding areas;

3. Anticipated economic growth in the area; and

4. Cost-effective emission reduction alternatives.

In addition, the reviewing authority must require a numerical limit on the quantity, rate or 

concentration of emissions for each regulated NSR pollutant emitted by each affected emissions unit, 

for which such a limit is technically feasible. The emission limitation required may also be included as 

pollution prevention techniques, design standards, equipment standards, work practices, operational 

standards or any combination thereof. However, the emission limitations must assure that each affected 
Page 7 of 21

emission unit will comply with all requirements of 40 CFR parts 60, 61, and 63, as well as any federal or 

tribal implementation plans that apply to the unit. Finally, the emission limitations required may not rely 

on a stack height that exceeds good engineering practice or any other dispersion technique, except as 

allowed by 40 CFR 51.118(b).

To address the requirements for establishing emission limitations, the following considerations were 

used for setting the limits in the proposed general permit for boilers:

1. Local air quality conditions – To address this requirement, the proposed general permit includes

more stringent heat input capacity limits in nonattainment areas because limiting the total heat 

input capacity of all boilers at a source resulted in sufficient reductions in potential emissions to 

ensure sources would still be below the major source thresholds. Also, the proposed general 

permit include more stringent limits on emissions of NOx and CO because limiting the NOx and 

CO emissions results in sufficient reductions in potential emissions to ensure sources can locate 

in nonattainment areas without contributing to violations of the National Ambient Air Quality 

Standards (NAAQS).

2. Typical control technology or other emission reduction measures used by similar sources in 

surrounding areas – For sources locating in attainment areas, the EPA looked at the control 

requirements specified by 40 CFR parts 60, 61 and 63. These regulations establish minimum 

technology and emission limitations that must be met nationally. Permittees must also meet the 

requirements of 40 CFR 49.154(c)(4) to ensure compliance with parts 60, 61, and 63. For sources 

locating in nonattainment areas, the EPA looked at the control requirements specified by the 

South Coast Air Quality Management District.

13 For this proposed general permit, the EPA

considered the following regulations that apply to boilers:

a. 40 CFR Part 60, Subpart Db - Standards of Performance for Industrial-CommercialInstitutional Steam Generating Units;

b. 40 CFR Part 60, Subpart Dc - Standards of Performance for Small Industrial-CommercialInstitutional Steam Generating Units;

c. 40 CFR Part 63, Subpart JJJJJJ - NESHAP for Industrial, Commercial, and Institutional 

Boilers Area Sources;

d. South Coast Air Quality Management District (SCAQMD), Rule 1146 - Emissions of 

Oxides of Nitrogen from Industrial, Institutional, and Commercial Boilers, Steam 

Generators, and Process Heaters;

e. 40 CFR 60 Subpart IIII – Standards of Performance for Stationary Compression Ignition 

Internal Combustion Engines; 

f. 40 CFR 60, Subpart JJJJ - Standards of Performance for Stationary Spark Ignition Internal 

Combustion Engines; and

g. 40 CFR 63 Subpart ZZZZ – NESHAP for Stationary Reciprocating Internal Combustion 

Engines.

The conditions in the Emission Limitations and Standards section of the general permit are 

developed from the NSR Rule, NSPS, NESHAP, SCAQMD Rule 1146, and the state permit 

 

13 South Coast Air Quality Management District, Rule 1146 - Emissions of Oxides of Nitrogen from Industrial, 

Institutional, and Commercial Boilers, Steam Generators, and Process Heaters, 

http://www.arb.ca.gov/DRDB/SC/CURHTML/R1146.HTM.
Page 8 of 21

examples. The derivation of the surrogate emissions limitations in the general permit are 

discussed fully in Section 5. The minor NSR thresholds are based on provisions of the Review of 

New Sources and Modifications in Indian Country rule at 40 CFR 49.153 and are provided in 

Table 1.

Under the proposed permit for boilers, each affected boiler must comply with the following 

limitations and standards:

a. Setbacks – The proposed general permit requires the exhaust from each 

boiler or heater to be located a minimum of 50 feet from the nearest 

property line and 150 feet from any adjacent residential or commercial 

establishment or place of public assembly;

b. Total Capacity - The total heat input capacity of all gas-fired boilers onsite 

shall be less than 160 MMBtu/hr, and less than 120 MMBtu/hr for liquid-fired 

boilers (this requirement varies by classification of ozone nonattainment 

area);

c. Individual Boiler Capacity - The capacity of each individual boiler shall be less 

than 100 MMBtu/hr;

d. Combined Boiler Capacity – The combined maximum rated capacity of all boilers 

and process heaters at the permitted source must not exceed certain capacity levels 

as laid out in the permit and that vary depending on are classification/designation;

e. Auxiliary Heaters – The maximum rated capacity of any individual process 

heater at this facility shall be:

i. Less than 10 MMBtu/hr if located at a permitted source in an ozone 

attainment, unclassifiable or attainment/unclassifiable area;

ii. Less than 10 MMBtu/hr if located at a permitted source in a marginal, 

moderate or serious ozone nonattainment areas;

iii. Less than 2 MMBtu/hr if located at a permitted source in a severe or 

extreme ozone nonattainment area;

iv. A process heater may exceed the above size limitations if it meets the 

emission limitations applicable to boilers;

f. Emergency Engines –Each emergency engine must be equipped with a nonresettable hour meter and, if using fuel oil, use diesel or biodiesel containing 

no more than 15 parts per million (ppm) (0.0015 percent) sulfur by weight.

The engines must also meet the following:

i. Newer emergency engines – model year 2006 or later for 

compression ignition engines and 2009 or later for spark ignition 

engines – must meet certain certification or emission requirements 

that are specified in the EPA emissions standards at 40 CFR Part 89, 

40 CFR Part 90 and 40 CFR Part 1048 or Table 1 to 40 CFR Part 60, 

Subpart JJJJ, as applicable;

ii. Older emergency engines are required to meet certain routine 

maintenance requirements, and must follow the manufacturer’s 

emission-related operation and maintenance instructions or the 

permittee must develop a maintenance plan, which must provide, to 

the extent practicable, for the maintenance and operation of the 

engine in a manner consistent with good air pollution control practice 

for minimizing emissions;
Page 9 of 21

g. NOx Limits – For boilers over 10 MMBtu/hr, NOx emissions shall not exceed 

30.0 parts per million, dry volume (ppmdv) at 3% O2 or 0.037 pounds 

(lbs)/MMBtu;

h. CO Limits – For boilers over 10 MMBtu/hr, CO emissions shall not exceed 

400.0 ppmdv at 3% O2 or 0.30 lbs/MMBtu;

i. Fuel Type/Sulfur Limit – Each affected boiler, heater, or engine burning liquid fuels 

shall use diesel or biodiesel and the sulfur content of diesel and biodiesel shall not 

exceed 0.0015 ppm by weight; 

j. Boiler Restrictions – Each boiler stack must be above the buildings in the 

vicinity, discharge vertically, and have no obstructions to gas flow such as rain 

caps, except for hinged rain caps

k. Opacity Limit – Boiler emissions shall be limited to 5 percent opacity or 

greater averaged over a six consecutive minute;

l. Boilers Tune-Ups – Boilers must undergo biennial tune-ups; and 

m. Severe or Extreme Ozone Nonattainment Areas – Boilers located in these 

areas are subject to more stringent regulations.

3. Anticipated economic growth in the area – The Reviewing Authority may consider anticipated 

economic growth when determining whether coverage under the general permit is justifiable. 

Considering, however, that the general permit sets emission standards that are consistent with 

what is required for boilers across the country in both attainment and non-attainment areas, we 

expect that this will rarely be a factor. 

4. Cost-effective emission reduction alternatives – The general permit sets emission standards that 

are consistent with what is required for boilers across the country. As such, the chosen 

technologies are considered widely available and consideration of more cost-effective 

alternatives is not necessary at this time. The EPA intends to periodically review technology 

costs in the future to determine when more stringent, cost-effective technologies become 

widely available.

40 CFR 49.155(a)(3) – Monitoring and Testing Requirements

The proposed general permit must include monitoring that is sufficient to assure compliance with the 

emission limitations that apply to the source. For boilers, the proposed general permit requires that a 

visible emissions survey is conducted on a weekly basis, and initial and continuing performance testing 

to verify compliance with the NOx and CO emission limitations.

40 CFR 49.155(a)(4) – Recordkeeping Requirements

The proposed general permit must include recordkeeping that is sufficient to assure compliance with 

the emission limitations and monitoring requirements, including certain statements listed in 40 CFR 

49.155(a)(4)(i) and (ii). In addition to the recordkeeping requirements in 40 CFR 49.155(a)(4)(i), under 

the general permit for boilers the permittee must maintain records of: fuel supplier certifications, 

emergency engine fuel use, visible emission surveys, the concentration of CO in the boiler exhaust,

emissions before and after the tune-up of each boiler, and any corrective actions taken as part of a tuneup of a boiler. The permittee must also maintain records of: (1) emergency engine maintenance 

activities; (2) emergency engine hours of operation, including the date, time, duration, and reason(s) for 

use; and (3) the results of each performance test.

40 CFR 49.155(a)(5) – Reporting Requirements
Page 10 of 21

The proposed general permit includes the reporting requirements listed in 40 CFR 49.1559(a)(5)(i) and 

(ii) related to annual reports and reporting of deviations. 

40 CFR 49.155(a)(6) – Severability Clause

The proposed general permit includes a severability clause to ensure the continued validity of the other 

portions of the permit in the event of a challenge to a portion of the permit. This condition is found in 

the General Provisions of the proposed general permit.

40 CFR 49.155(a)(7) – Additional Provisions

The proposed general permit contains the additional provision required for each permit. These 

conditions are found in the General Provisions, Changes to this General Permit, and Obtaining Coverage 

under this General Permit sections of the proposed general permit.

4.4 Requirements for Sources Located in Nonattainment Areas

The EPA has included additional requirements for sources locating in ozone nonattainment areas. These 

requirements vary depending upon the severity of the location’s ozone nonattainment classification. 

The requirements specify lower capacity limits on liquid-fired boilers located in severe ozone 

nonattainment areas, lower capacity limits on natural gas-fired boilers located in severe and extreme 

ozone nonattainment areas, lower horsepower limits on generators located in severe and extreme 

ozone nonattainment areas, a prohibition on oil-fired boilers in extreme ozone nonattainment areas, 

and lower emission limits for all boilers located in severe or extreme ozone nonattainment areas. The 

limits on capacity will ensure that the general permit only applies to true minor sources locating in these 

nonattainment areas.

4.5 Additional Permit Requirements

The proposed general permit requires the exhaust from each boiler or heater to be located a minimum 

of 50 feet from the nearest property line and 150 feet from any adjacent residential or commercial 

establishment or place of public assembly. 

4.6 Requirements of the Endangered Species Act and National Historic Preservation Act

Prior to seeking coverage under this general permit, sources must satisfactorily address the permitting 

requirements related to the Endangered Species Act and National Historic Preservation Act. Attached to 

the request for coverage document for the boilers general permit, the EPA provides guidance to assist

sources in complying with these two statutes.

5. Emission Limitations14 and Surrogate Heat Input Capacity Limits 

5.1 Developing the Surrogate Limits for the Emissions Limitations

The draft general permit includes heat input capacity limits for boilers and combined maximum 

horsepower limits for emergency generators that combined serve as surrogate emissions limitations for 

 

14 The definition of emission limitation used in this background document is the one provided in the Indian Country 

Minor NSR rule (described in Section 4.3) and includes requirements established by the reviewing authority that 

relate to the operation of a source, which allows for the use of production throughput limits.
Page 11 of 21

both gaseous and liquid fueled boilers (see tables 4 and 5). The heat input capacity limits for boilers vary 

depending upon the particular ozone attainment or nonattainment classification in the area in which the 

source will locate. The capacity limits were established as surrogate emissions limitations in order to 

limit emissions below the thresholds for the Title V and major NSR permitting programs.

The horsepower limits were included in the permit because many facilities that have boilers, such as 

manufacturing facilities, hotels, educational institutions, and public services, also have emergency 

generators. Thus, the general permit includes an allowance for emissions from any generator engines 

that may be onsite. As was done with boilers, power output limits for generator engines were 

established as a surrogate for emission limits. These limits are based on 500 hours of operation per year. 

The proposed general permit includes the combined maximum power output limits for all emergency 

engines onsite as listed in Table 5 below. As with boilers, the power output limits are set at levels 

intended to keep the source’s combined emissions below the NOx and greenhouse gas (GHG) major 

source thresholds.

The heat input capacity limits (combined with the horsepower limits) in the general permit for sources 

located in attainment areas correspond to the source-wide PTE at which a source would become a 

major source and subject to Title V permitting (referred to hereafter as “the Title V major source 

threshold”). In attainment areas, the Title V major source threshold is 100 tpy for any criteria pollutant, 

10 tpy for a single HAP, and 25 tpy for any combination of HAPs. The Title V major source threshold in 

nonattainment areas varies by the pollutant and the nonattainment classification. The major source 

emissions thresholds for facilities located in nonattainment areas are set at the thresholds in Table 2 for 

each pollutant and nonattainment status, which serve as the thresholds for both the major NSR and Title 

V permitting programs.

Boilers emit a multitude of pollutants, but generally boilers emit NOx at levels high enough to make NOx

a controlling pollutant of concern. However, in this case EPA also considered GHG emissions to ensure 

sources applying for the general permit are not subject to regulation as a major source for GHGs (as 

defined in 40 CFR 71.2 and 40 CFR 52.21) for the Title V and Prevention of Significant Deterioration (PSD) 

programs. GHGs emissions (as CO2 (carbon doxide) equivalent or CO2e) were determined to be the 

pollutant of concern for sources locating in attainment areas, as well as in marginal and moderate 

nonattainment areas. For this reason, the EPA found it necessary to establish heat input capacity limits 

(and horsepower limits) as surrogate emissions limitations for the boilers and engines that are part of a

stationary source that correspond to the emissions rates for NOx and CO2e in Table 3. This ensures that 

sources granted coverage under this proposed general permit are not subject to major source NSR or 

Title V for GHG emissions because those emissions are kept below 100,000 tpy. In serious, severe, and 

extreme areas, because the major source threshold for NOx is lower, the EPA established a lower limit 

for boilers located at stationary sources in those areas to, again, assure that emissions for sources 

eligible for this proposed general permit are below major source levels. 

Table 3: Emission Rates used to Determine Surrogate Emission Limitations 

for Facilities with Boilers

Pollutant of 

Concern

Attainment, Unclassifiable 

or Attainment / 

Unclassifiable Areas

Nonattainment Areas

NOX 100 tpy 10 tpy

(extreme ozone areas)
Page 12 of 21

Pollutant of 

Concern

Attainment, Unclassifiable 

or Attainment / 

Unclassifiable Areas

Nonattainment Areas

25 tpy

(severe ozone areas)

50 tpy

(serious ozone areas)

100 tpy

(marginal and moderate ozone areas)

CO2e 100,000 tpy 100,000 tpy

The EPA evaluated the emission rates at which a new or modified source would become a major source 

under Title V. This is 100 tpy for PM10, PM2.5, SO2, NOX, VOC, and CO in attainment areas and 100,000 tpy 

for GHGs. The EPA estimates the potential emissions of a boiler based on the boiler’s maximum heat 

input capacity, fuel used, 8,760 hours of operation, and emissions factors for the type of burner in the 

boiler. In order to limit emissions to below the NSR major source thresholds, the EPA has chosen to limit 

the heat input capacity of the boiler. This capacity limit varies according to the type of fuel burned, and 

the NAAQS15 attainment status of the area where the boiler will be located. 

In attainment areas, the calculations indicate that GHGs are the limiting pollutant. The EPA backcalculated the boiler capacity and type of fuel used that yielded emissions at these limits by using 8,760 

hours of operation and emission factors from AP 42, Chapters 1.3 and 1.4. These results are shown in 

Table 4 below. Sample calculations for GHG emissions from a site with a 160 MMBtu/hr natural gas-fired 

boiler, a 20 MMBtu/hr natural gas-fired auxiliary heater, and a 1,500 horsepower diesel emergency 

generator are shown below. GHG emissions were calculated using carbon dioxide (CO2) emissions. 

Potential emissions of other GHGs (e.g. NO2) are considered negligible for this calculation and the 

resulting combined CO2 emissions are sufficiently below 100,000 tpy to ensure there is not a potential to 

exceed the 100,000-tpy CO2e threshold. 

160 MMBtu/hr Boiler (natural gas):

160 MMBtu/hr x 1 MMscf/1020 MMBtu x 120,000 lb CO2/MMscf x 8,760 hrs/year x 1 ton/2,000 lbs = 

84,113 tons CO2/year

20 MMBtu/hr Heater (liquid-fueled):

20 MMBtu/hr x 1 MMscf/MMBtu x 120,000 lb CO2/MMscf x 8,760 hrs/year x 1 ton/2,000 lbs = 

10,306 tons CO2 /year

1,500 Hp Emergency Generator:

1,500 Hp x 1.15 lb CO2 /hp-hr x 500 hrs/year x 1 ton/2,000 lbs = 431 tons CO2 /year

 

15 EPA, National Ambient Air Quality Standards, http://www.epa.gov/air/criteria.html. 
Page 13 of 21

Total CO2 emissions = 94,850 tons CO2/year

Table 4: Combined Maximum Heat Input Capacity Limits for Boilers

Located in Ozone Attainment and Nonattainment Areas

Emission Units

Ozone Attainment Classification

Attainment, 

Unclassifiable 

or Attainment/ 

Unclassifiable

Marginal, 

Moderate, or 

Serious

Severe Extreme

All Natural Gas-fired Boilers 

Rated ≥ 10.0 MMBtu/hr 160 MMBtu/hr 160 MMBtu/hr

100 

MMBtu/hr

100 

MMBtu/hr

All Natural Gas-fired Boilers 

and Auxiliary Heaters 

Rated < 10.0 MMBtu/hr

20 

MMBtu/hr

20 

MMBtu/hr

20 

MMBtu/hr

20 

MMBtu/hr

All Liquid-fueled Boilers* 

Rated ≥ 10.0 MMBtu/hr 120 MMBtu/hr 120 MMBtu/hr

100 

MMBtu/hr NA**

All Liquid-fueled Boilers* 

and Auxiliary Heaters 

Rated < 10.0 MMBtu/hr

20 

MMBtu/hr

20 

MMBtu/hr

20 

MMBtu/hr NA**

* A boiler that typically burns both liquid and gaseous fuels is limited as if burning exclusively liquid fuels. 

A natural gas unit may use fuel oil as a backup emergency fuel for up to 500 hours per year without 

being limited as if it were a liquid-fueled unit.

** The permit does not allow liquid-fueled boilers in extreme ozone nonattainment areas.

 Table 5: Combined Maximum Horsepower Limits for Emergency Generators 

Located in Ozone Attainment and Nonattainment Areas

Emission Units

Ozone Attainment Classification

Attainment, 

Unclassifiable 

or Attainment/ 

Unclassifiable

Marginal, 

Moderate, or 

Serious

Severe Extreme

All Emergency Generators 

(All Fuels) 1500 hp 1500 hp 1000 hp 750 hp

5.2 Emission Limitations

Three considerations form the basis for the emission limitations for the general permit:

1. Are there any EPA regulation-based emission limitations?

2. What do actual emissions data from the 2011 National Emissions Inventory (NEI)16 indicate 

about the size profile of the source category? 

3. Where do state programs establish eligibility limits? 

5.2.1 EPA Regulation-Based Emissions Limitations 

Facilities in attainment areas with criteria pollutant emissions greater than 100 tpy are subject to Title V 

operating permit programs. This general permit is not intended to cover Title V major sources. 

 

16 For more information, go to: http://www.epa.gov/ttnchie1/net/2011inventory.html. 
Page 14 of 21

Therefore, the surrogate emissions limitations provided as heat input capacity limits and horsepower 

limits included in the proposed permit are based on keeping GHG emissions of sources below the Title V 

major source threshold of 100,000 tpy of GHGs for boilers subject to this general permit and located in 

attainment areas. Keeping emissions of boilers subject to this general permit below the GHG Title V 

threshold also prevents the source’s GHG emissions from exceeding 100,000 tpy which would make the 

source subject to the major source PSD program.

For facilities located in nonattainment areas, this general permit is not intended to cover NSR major 

sources. The NSR major source thresholds vary depending on the classification of the nonattainment 

areas and are provided in Table 2 and are expressed as emission rates in Table 3. The surrogate emission 

limitations established in the proposed permit as heat input capacity limits and horsepower limits are 

based on the emission rates. For marginal and moderate ozone nonattainment areas the surrogate 

emissions limitations are based on keeping GHG emissions of sources below the Title V major source 

threshold of 100,000 tpy of GHGs for boilers subject to this general permit and located in those areas. 

Keeping emissions of boilers subject to this general permit below 100,000 tpy for GHGs also prevents 

the source’s emissions from exceeding the 100 tpy Title V threshold for other pollutants. As noted 

above, in serious, severe, and extreme areas, because the major source threshold for NOx is lower, the 

EPA established a lower limit for boilers located at stationary sources in those areas to assure that 

emissions for sources eligible for this proposed general permit are below major source levels.

5.2.2 Analysis of NEI Data

The EPA analyzed 2011 NEI data for certain types of existing facilities across the entire U.S. that have 

boilers to evaluate the emission limitations established in the general permit. Although the NEI does not 

include potential emissions information for sources in Indian country, it reflects the actual emissions 

from boiler facilities in 50 states. In order to analyze facilities whose emissions are similar to those for 

sources potentially subject to the Indian Country Minor NSR rule, the EPA selected facilities for analysis 

with the North American Industry Classification System (NAICS) codes listed in Table 6. For sources with 

these NAICS codes, the EPA selected actual emissions17 within the ranges listed in Table 7.

 Table 6: NAICS Codes Selected for Boilers

NAICS Code Description

11  Agriculture, Greenhouses

2211**  Electric Power Generation

311*** Food Manufacturing

321*** Wood Product Manufacturing (except sawmills)

327*** Nonmetallic Mineral Product Manufacturing (except ready-mix concrete)

424*** Wholesale Trade, Nondurable Goods

611110 Elementary And Secondary Schools

611210 Junior Colleges

611310 Colleges, Universities, And Professional Schools

62  Health Care And Social Assistance

721120 Casino Hotels

813110 Religious Organizations

92** ** Public Administration

 

17 Only point source NEI data were used for this analysis.
Page 15 of 21

 Table 7: Emission Ranges Selected for Facilities with Boilers

Criteria Pollutants NOX

Attainment Area

 Min. Emissions (tpy) 10

 Max. Emissions (tpy) 250

Nonattainment Area

 Min. Emissions (tpy) 5

 Max. Emissions (tpy) 250

The 2008 NEI data does not include emissions information for total PM. The EPA analyzed the emissions 

rates listed in Table 5 that were used to establish the surrogate emissions limitations and selected the 

facilities with emission levels similar to the facilities potentially subject to the NSR minor program, i.e., 

the facilities with emissions greater than the minor NSR applicability thresholds in Table 1 of 40 CFR 

49.153 (Indian Country Minor NSR rule) and less than the PSD major source threshold of 250 tpy. For 

purposes of this analysis, facilities located in nonattainment areas are defined as facilities located in 

counties that are designated nonattainment for the pollutant being analyzed. 

With the NAICS codes listed in Table 6 and the emission ranges defined in Table 7, the EPA identified the 

boiler facilities located in attainment and nonattainment areas for NOx. The EPA is providing the number 

of facilities (and average emissions) under the proposed emissions rates and above the minor source 

thresholds. 

Table 8: Number of Facilities and Average Emissions for Facilities with Boilers Selected

Criteria Pollutants Number of Facilities

Attainment Areas

NOx

Facilities >10 tpy and < 100 tpy 1,036 (26% of facilities 

covered)

Average Emissions (tpy) 32

Facilities > 100 tpy and < 250 tpy 166

Average Emissions (tpy) 158

Nonattainment Areas

NOx (marginal and moderate)

Facilities >5 tpy and < 100 tpy 0 (0% of facilities covered)

Average Emissions (tpy) N/A

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

NOx (serious)

Facilities >5 tpy and < 50 tpy 0 (0% of facilities covered)

Average Emissions (tpy) N/A

Facilities > 50 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

NOx (severe)

Facilities >5 tpy and < 25tpy 0 (0% of facilities covered)
Page 16 of 21

Criteria Pollutants Number of Facilities

Average Emissions (tpy) N/A

Facilities > 25 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

NOx (extreme)

Facilities >5 tpy and < 10 tpy 0 (0% of facilities covered)

Average Emissions (tpy) N/A

Facilities > 10 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

5.2.3 State Program Limits

Table 9 presents the limits in general permits and permits by rule issued by the states. These state 

permits limit emissions by limiting fuel usage, fuel sulfur content, boiler capacity, or by imposing direct 

limitations on emissions for criteria pollutants. The upper limits in state permits vary considerably. Most 

of the state permits limit either: fuel throughput and emissions, or total capacity and emissions, while 

several (Arizona, Michigan, Oregon, Pennsylvania, South Carolina, and Washington) place limits on fuel 

usage/sulfur content, pollutant emissions, and boiler capacity. Several states require that applicants 

calculate the PTE of criteria pollutants. A comparison of requirements for attainment and 

nonattainment areas is not possible; most state programs, with the exception of Pennsylvania, do not 

specify distinct requirements for nonattainment areas.

 

Table 9: State Program Limits

State Fuel Usage Limits Criteria Pollutant Emission 

Limitations

Boiler 

Capacity 

Limits

Visible 

Emissions 

Limits

Arizona: 

non-NSPS 

boilers

Natural gas or diesel 

fuel.

S02: 1lb/MMBtu and

PM: 1.02 x (MMBtu)^0.769.

< 100 MMBtu.

< 15% 

opacity.

Arizona: 

NSPS boilers

Natural gas, LPG, and

diesel fuel.

S02: fuel=0.5% sulfur and

PM: 1.02(MMBtu)^0.769.

10-100 

MMBtu 

constructed 

after 6/9/89.

< 20% opacity 

for dieselfueled.

Delaware Natural gas, diesel, and 

No.6 fuel oil.

Entire source must be true minor.

Natural gas

boiler > 15 

MMBtu needs 

permit and

fuel oil boiler > 

10 MMBtu 

needs permit.

N/A
Page 17 of 21

State Fuel Usage Limits Criteria Pollutant Emission 

Limitations

Boiler 

Capacity 

Limits

Visible 

Emissions 

Limits

Indiana

Natural gas: 0.3 to <10 

MMBtu: 1,000 

MMCF/year;

natural gas: 10 to 100 

MMBtu: 714 

MMCF/year;

natural gas: > 100 

MMBtu: 181 

MMCF/year; fuel oil #1 

and #2: 1,408 

Kgals/year; and

LPG: 5,263 MMCF/year.

N/A

Capacity limit 

depends upon 

unit size.

< 20% 

opacity.

Maine Liquid fuel: < 2.0% 

sulfur.

PTE < 100 all criteria pollutants;

PTE < 50 VOC;

PTE < 10 single HAP;

PTE <25 total HAP; and

PM: 0.2 lb/MMBtu.

> 10 MMBtu 

needs permit.

Natural gas: 

<10% 

opacity;

No. 2 fuel oil: 

< 20% 

opacity; and

Nos. 4, 5, 6 

fuel oil: < 

30% opacity.

Maryland 

Natural gas, LPG, or 

diesel fuel: 

< 0.3% sulfur.

Rotary cup burners prohibited.

From 1 to 10 

MMBtu.

< 20% opacity

and

0% opacity in 

certain 

counties.

Michigan

Natural gas or propane 

only and use < 1,400 

MMscf/year.

NOx: < 0.05lb/MMBtu and 

Low-NOx burner required. < 100 MMBtu.

150 foot 

setback from 

nearest 

residence

< 20% 

opacity.

Ohio –

general 

permit for 

10-17.9 

MMBtu/hr

Fuel: < 0.5% sulfur and 

use < 700,000 gallons of 

No. 2 fuel oil per year.

PM < 0.014 lb/MMBtu and 0.92 tpy;

VOC < 0.011 lb/MMBtu and 0.85 tpy;

NOx < 0.14 lb/MMBtu and 9.88 tpy;

CO < 0.082 lb/MMBtu and 6.46 tpy; 

and

SO2 < 0.50 lb/MMBtu and 24.87 tpy.

N/A <10 % 

opacity.

[Ohio issues five other General Permits for boilers in the capacity range of 18 - 39.9 MMBtu/hr]

Ohio –

general 

permit for 

40-45 

MMBtu/hr

Fuel: < 0.5% sulfur and 

use < 700,000 gallons of 

No. 2 fuel oil per year.

PM < 0.014 lb/MMBtu and 1.80 tpy;

VOC < 0.011 lb/MMBtu and 2.13 tpy;

NOx < 0.14 lb/MMBtu and 21.52 tpy;

CO < 0.082 lb/MMBtu and 16.23 tpy; 

and

SO2 < 0.50 lb/MMBtu and 24.87 tpy.

N/A <10 % 

opacity.

Oklahoma N/A

PTE < 100 tpy for criteria pollutants;

PTE < 10/ 25 for HAPs; and actual 

Emissions < 40 tpy.

N/A <20% 

opacity.
Page 18 of 21

State Fuel Usage Limits Criteria Pollutant Emission 

Limitations

Boiler 

Capacity 

Limits

Visible 

Emissions 

Limits

Oregon

No.1 fuel oil: < 0.3%

sulfur;

No.2 fuel oil : < 0.5% 

sulfur; residual oil : < 

1.75% sulfur; and used 

oil: < 0.5% sulfur.

Source-wide Emission Limits: 

PM < 24 tpy

PM10 < 14 tpy

SO2 < 39 tpy

NOx < 39 tpy

CO < 99 tpy

VOC < 39 tpy

PM10 <4.5 tpy for Medford-Ashland 

AQMA;

PM Emissions Less than 0.1 

grains/dry standard cubic foot (dscf)

at 12% CO2, but stricter for certain 

counties; and

NSPS standard: PM emissions less 

than 0.03 lb/MMBtu.

Oil: >10 

MMBtu;

natural gas, 

propane, and

butane: > 30 

MMBtu; and 

total: 10 to 

250 MMBtu.

<20% 

opacity.

Pennsylvania

Natural gas, LPG, or No. 

2 fuel oil only

Fuel oil sulfur content of 

0.3% or 0.2%, depending 

upon region

PTE < major source thresholds 

PTE of VOC < 50 tpy

exempt if PTE is below certain levels;

stack test for NOx and CO required

BACT:

natural gas: 30 ppmdv NOx at 3% O2;

No.2 fuel oil: 90 ppmdv NOx at 3% O2;

No.2 fuel oil: 300 ppmdv CO at 3% O2; 

and

PM: less than 0.4 lb/MMBtu.

< 50 MMBtu

and units with 

capacity > 10 

MMBtu must 

utilize low-NOx

burners, flue 

gas 

recirculation, 

and low NOx

fuel.

<20% 

opacity.

South 

Carolina 

Natural gas, propane, 

No.2 fuel oil, diesel, or 

biodiesel only and fuel 

sulfur content of 0.05% 

or less.

Facility-wide PTE < major source 

thresholds; install low-NOx burners, 

biannual tune-up; and

natural gas and propane: 

0.036 lbs NOx/MMBtu

Fuel oil:

0.15 lbs NOx/MMBtu 

0.6 lbs PM/MMBtu

2.3 lbs SO2/MMBtu.

Total capacity 

< 100 MMBtu 

and maximum 

size for a 

boiler not 

burning 

natural gas or 

propane is 30 

MMBtu.

<20% 

opacity.
Page 19 of 21

State Fuel Usage Limits Criteria Pollutant Emission 

Limitations

Boiler 

Capacity 

Limits

Visible 

Emissions 

Limits

Washington

Natural gas, LPG, 

propane, and diesel 

only.

Facility-wide PTE < major source 

thresholds; not a PSD modification;

PM: 0.02 grains/dscf at 3% O2

Natural gas or LPG: 

NOx: 9 parts per million volume 

(ppmv)

CO: 50 ppmv

SO2: pipeline quality gas;

Propane: 

NOx: 30 ppmv

CO: 100 ppmv

SO2: 8.1 grains sulfur/100 scf fuel; 

and

Diesel: 

NOx: 35 ppmv

CO: 100 ppmv

SO2: Diesel: 40 CFR 80.520.

Natural gas, 

LPG, propane: 

4 to 50 

MMBtu total

and diesel: 1 

to 50 MMBtu 

total.

100 ft 

setback to 

property line; 

stack height 

must be 1.06 

to 1.3 times 

the height of 

the nearest 

roof within 

100 feet of 

the stack; 

and < 5%

opacity.
Page 20 of 21

References:

40 CFR 49.151 – 40 CFR 49.173, Indian Country Air Quality Planning and Management.

http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title40/40cfr49_main_02.tpl

40 CFR Part 60, Subpart Db—Standards of Performance for Industrial-Commercial-Institutional Steam 

Generating Units. http://www.ecfr.gov/cgibin/retrieveECFR?gp=&SID=6cc85915f2a4fcf32ae4fe037a13a53f&r=SUBPART&n=40y7.0.1.1.1.11#40:7.0

.1.1.1.11.151.5

40 CFR Part 60, Subpart Dc—Standards of Performance for Small Industrial-Commercial-Institutional 

Steam Generating Units. http://www.ecfr.gov/cgi-bin/textidx?SID=fe1381d2a7d4ee8c16a4aac98b6c6d29&node=40:7.0.1.1.1.12&rgn=div6

40 CFR Part 60, Subpart IIII, Standards of Performance for Stationary Compression Ignition Internal 

Combustion Engines. http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=f2c4f71bd50d2a8883adafec36732010&rgn=div6&view=text&node=40:6.0.1.1.1.98&idn

o=40

40 CFR Part 60, Subpart JJJJ, Standards of Performance for Stationary Spark Ignition Internal Combustion 

Engines. http://www.ecfr.gov/cgi-bin/textidx?SID=093578d89c2100a85b3bd00b188a5413&node=40:7.0.1.1.1.98&rgn=div6

40 CFR Part 63, Subpart ZZZZ, National Emission Standards for Hazardous Air Pollutant for Reciprocating 

Internal Combustion Engines (RICE). http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&rgn=div6&view=text&node=40:13.0.1.1.1.1&idno=40

40 CFR Part 63, Subpart JJJJJJ—National Emission Standards for Hazardous Air Pollutants for Industrial, 

Commercial, and Institutional Boilers Area Sources. http://www.ecfr.gov/cgi-bin/textidx?SID=fe1381d2a7d4ee8c16a4aac98b6c6d29&node=40:15.0.1.1.1.23&rgn=div6

AP 42, Fifth Edition, Compilation of Air Pollutant Emission Factors, Volume 1: Stationary Point and Area 

Sources. http://www.epa.gov/ttn/chief/ap42/index.html

Arizona Department of Environmental Quality, General Permits.

http://www.azdeq.gov/environ/air/permits/class.html#general, 

http://www.azdeq.gov/function/forms/appsair.html#source, 

http://www.azdeq.gov/environ/air/permits/download/gnblrpermit.pdf

Delaware Department of Natural resources and Environmental Control, Office of Environmental 

Protection, Division of Air Quality. 

http://www.dnrec.delaware.gov/dwhs/Info/Regs/Documents/Small%20Boiler%20Permits.pdf

Federal Register Vol. 76, No. 127, July 1, 2011, Pages 38748-38808, “Review of New Sources and 

Modifications in Indian Country; Final Rule” (Indian Country NSR Rule). 

https://www.federalregister.gov/articles/2011/07/01/2011-14981/review-of-new-sources-andmodifications-in-indian-country
Page 21 of 21

Illinois Environmental Protection Agency, Air Permit Programs, Air Permit Applications and Guidance, 

Lifetime Permits. http://www.epa.state.il.us/air/permits/lifetime.html, 

http://www.epa.state.il.us/air/permits/boiler-application-guidance-july12.pdf

Indiana Department of Environmental Management, IDEM Permit Guide, Source Specific Operating 

Agreements (SSOAs), 326 IAC 2-9-13, External Combustion Sources. 

http://www.in.gov/legislative/iac/T03260/A00020.PDF? 

Maryland Department of the Environment, Permits, Air Quality General Permits to Construct.

http://www.mde.maryland.gov/programs/Permits/AirManagementPermits/AirQualityGeneralPermit/Pa

ges/index.aspx

Michigan Department of Environmental Quality, Air Quality Division.

http://www.deq.state.mi.us/aps/generalpermits.shtml, http://www.michigan.gov/documents/deq/deqaqd-pti-boiler_applicability_spec_cond_356451_7.pdf

Ohio Environmental Protection Agency, General Permit Program, Boilers.

http://www.epa.ohio.gov/dapc/genpermit/genpermits.aspx, 

http://www.epa.ohio.gov/dapc/genpermit/gensources.aspx#boilers

Oklahoma Department of Environmental Quality, General Permits and Permits by Rule.

http://www.deq.state.ok.us/aqdnew/permitting/genperm.htm

Oregon Department of Environmental Quality, Air Quality, General Air Contaminant Discharge Permits.

http://www.deq.state.or.us/aq/permit/acdp/general.htm

Pennsylvania Department of Environmental Protection, Bureau of Air Quality, Air Quality General 

Permits. http://www.dep.state.pa.us/dep/deputate/airwaste/aq/permits/gp.htm, 

http://www.elibrary.dep.state.pa.us/dsweb/View/Collection-9743

South Carolina Department of Health and Environmental Control, Air Quality Permitting, Registration 

Permits.

http://www.scdhec.gov/environment/baq/Permitting/RegistrationPermits/fuel_combustion.asp

South Coast Air Quality Management District, Rule 1146 - Emissions of Oxides of Nitrogen from 

Industrial, Institutional, and Commercial Boilers, Steam Generators, and Process Heaters.

http://www.arb.ca.gov/DRDB/SC/CURHTML/R1146.HTM

Washington Department of Ecology, Air Quality, Air Permits, General Orders of Approval.

http://www.ecy.wa.gov/programs/air/AOP_Permits/Boiler/GeneralOrders.htm