United States Environmental Protection Agency

General Permit or Permit by Rule for New or Modified 

Minor Sources of Air Pollution in Indian Country

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

Background Document: True Minor Source Hot Mix Asphalt Plants General 

Permit

Version 1.0

Last modified: November 14, 2013

1. Hot Mix Asphalt Plants Source Category Definition 

For purposes of this general permit, a hot mix asphalt (HMA) plant is a facility which manufactures hot mix 

asphalt by heating and drying aggregate and mixing with asphalt cements. An HMA plant is comprised of any 

combination of the following activities: dryers, liquid asphalt storage tanks, fuel oil storage tanks, auxiliary 

heaters (including hot oil heaters), material storage handling and transfer systems, generators, storage 

bins/silos, storage piles, and haul roads. An HMA plant can be constructed as a permanent plant, a skid-mounted 

(easily relocated) plant, or a portable plant. The proposed Minor Source HMA General Permit only covers HMA 

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

2. Source Category Characterization

HMA paving materials are a mixture of size-graded, high quality aggregate (which can include reclaimed asphalt 

pavement (RAP)), and liquid asphalt cement, which is heated and mixed in measured quantities to produce 

HMA. Aggregate and RAP (if used) constitute over 92 percent by weight of the total mixture. Aside from the 

amount and grade of asphalt cement used, mix characteristics are determined by the relative amounts and 

types of aggregate and RAP used. A certain percentage of fine aggregate (less than 74 micrometers in physical 

diameter) is required for the production of good quality HMA. (AP-42, Chapter 11.1 – Hot Mix Asphalt Plants)

There are four types of HMA plants based on manufacturing process: (1) batch mix plants, (2) continuous mix 

(mix outside dryer drum) plants, (3) parallel flow drum mix plants, and (4) counterflow drum mix plants. About 

85 percent of plants being manufactured today are of the counterflow drum mix design, while batch plants and 

parallel flow drum mix plants account for 10 percent and 5 percent respectively (AP-42, Chapter 11.1 – Hot Mix 

Asphalt Plants).

Emissions from HMA plants consist of: (1) combustion emissions from mixer/dryers, auxiliary heaters, and 

generators; and (2) particulate emissions from the mixing/drying process, material handling process, and fugitive 

emissions from haul roads. Carbon monoxide (CO) emissions from batch mix plants are significantly higher than 

the CO emissions from drum mix plants due to the incomplete combustion process occurring in the batch 

mixer/dryers. 

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 

appropriate elements in developing the documents and regulations in the general permit for this source 

category. The following states and local governments have specific NSR minor programs (such as General Permit 

and General Order) for HMA plants: Alaska, Arkansas, Arizona, Mississippi, New Mexico, Pennsylvania, South 

Carolina, Washington, Wisconsin, and West Virginia. The requirements for the state permitting programs related 

to HMA plants are summarized in Attachment A. General Permits from these states were chosen for 

examination because of characteristics they possess:
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Readily available; 

Clear throughput limits; and 

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

o Limitations and standards, and 

o Monitoring, testing, recordkeeping, and reporting requirements.

For the ten state general permit programs reviewed, the permit requirements can be categorized into the 

following four categories:

Emission Limits: Most of the state permit programs reviewed contain emission limits for all criteria 

pollutants. The emission limits typically range from 80 tons per year (tpy) to 100 tpy. The permit 

programs in Arkansas and New Mexico have a lower emission limitation of 50 tpy for sulfur dioxide 

(SO2). 

Production/Capacity Limits: Most of the state permit programs reviewed include asphalt production 

limits. The limits vary depending on the type of mixer and the attainment status of the location where 

the plant will be located. The permit program for Washington also includes a capacity limit of 150 

MMBtu/hour for the drum mixer/dryer. The permit program for Wisconsin includes a capacity limit of 

700 tons/hour for the asphalt plant. The capacity limits for heaters and engines can be found in the state 

permit programs for New Mexico and South Carolina.

Fuel Limits: All of the state permit programs reviewed, except for the permit program for Arizona, 

include some kind of fuel restriction, such as on the fuel types allowed, fuel usage limits, and sulfur 

content limits. In general, all the state programs reviewed allow the use of natural gas, propane and 

No.2 fuel oil (diesel). Few state programs allow the use of waste oils. The state program for Mississippi 

also includes a hazardous air pollutant (HAP) content limit for waste oil.

Other requirements: Most of the state permit programs reviewed include requirements for a fugitive 

dust control plan. The specific requirements in this control plan vary by state. Some of the states include 

operating hour limits for the production unit and/or emergency generator. The state permit program for 

Alaska includes setback requirements for the production unit and generator engine from the nearest 

residence. The state permit program for West Virginia also includes capacity limits for storage tanks.

In addition, all the state general permits reviewed incorporate the requirements of NSPS, Subpart I (Standards of 

Performance for Hot Mix Asphalt Facilities) and NSPS, Subpart Kb (Standards of Performance for Volatile Organic 

Liquid Storage Vessels, (Including Petroleum Liquid Storage Vessels) for Which Construction, Reconstruction, or 

Modification Commenced After July 23, 1984). 

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 HMA plants. 

These consist of the following documents: 
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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, throughput, 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

Potential to Emit (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, raw material throughput, 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 NSR minor source; and

Be below the emissions limitations established for the general permit.

Facilities with a PTE lower than the minor NSR thresholds specified in Table 1 of Indian Country 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. 

 Table 1: Minor NSR Thresholds in 40 CFR 49.153

Pollutant Attainment Area Nonattainment Area

CO 10 tons per year (tpy) 5 tpy

Particulate Matter 

(PM) 10 tpy 5 tpy

PM10 5 tpy 1 tpy

PM2.5 3 tpy 0.6 tpy

Sulfur Dioxide (SO2) 10 tpy 5 tpy

Nitrogen Oxides (NOX) 10 tpy 5 tpy

Volatile Organic 

Compounds (VOC) 5 tpy 2 tpy

Under current EPA policy, only true NSR minor 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:
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 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.

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 meet the throughput limits and operating requirements established in 

this general permit. The specific requirements for the proposed general permit are discussed in Sections 4.3 and 

4.4. The emissions associated with the throughput limits are lower than the NSR major source thresholds and 

were derived as described below in Section 5. 

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 Tribal 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 we believe 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.
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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. 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-bycase 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 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 HMA plants:

1. Local air quality conditions – To address this requirement, the proposed general permit does not allow 

sources to locate in severe or extreme ozone nonattainment areas or serious CO nonattainment areas 

and requires sources locating in certain other nonattainment areas to meet more stringent 

requirements. This includes more stringent emission limitations, as well as, more stringent fuel use 

limits. We did not include more stringent production limits for sources in nonattainment areas because 

limiting fuel use resulted in sufficient reductions in potential emissions to ensure sources would still be 

below the major source thresholds. However, fuel use limits have the effect of also limiting a sources 

production.

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

areas – For sources locating in attainment areas we 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 and also meet the requirements of 40 CFR 49.154(c)(4) to ensure compliance 

with parts 60, 61, and 63. For this proposed general permit we considered regulations that apply to the 

equipment at HMA facilities:

a. 40 CFR 60 Subpart I – Standards of Performance for Hot Mix Asphalt Facilities;

b. 40 CFR 60 Subpart Kb – Standards of Performance for Volatile Organic Liquid Storage Vessels 

(Including Petroleum Liquid Storage Vessels) for Which Construction, Reconstruction, or 

Modification Commenced after July 23, 1984;

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

Combustion Engines; and
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d. 40 CFR 63 Subpart ZZZZ – National Emission Standards for Hazardous Air Pollutions for 

Stationary Reciprocating Internal Combustion Engines.

These regulations cover emissions from dryers and mixers at HMA facilities:

The South Coast Air Quality Management Districts Rule for nitrogen oxides (NOX) Reductions from 

Miscellaneous Sources (CA Rule 1147) for operations located in ozone nonattainment areas;

The South Coast Air Quality Management Districts Rule for NOX Reductions from Miscellaneous 

Sources (CA Rule 1155) for operations located in particulate matter less than 2.5 micrometers 

(PM2.5) nonattainment areas; and

California San Joaquin Valley Rule for Dryers, Dehydrators, and Ovens (San Joaquin Rule 4309) for 

operations located in CO nonattainment areas.

The General Terms and Conditions in the general permit are a standardized set of boilerplate conditions 

included with General Permits. The conditions in the Specific Terms and Conditions section of the 

general permit are developed from the NSR Rule, NSPS, NESHAP, and the state permit examples.

The derivation of the emissions limitations and the production and fuel usage limits in the applicability 

questionnaire, application, and Specific Terms and Conditions section of 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 also discussed fully in Section 

5.

The affected emission units under this proposed general permit include the following:

Dryers;

Systems for screening, handling, storing, and weighing hot aggregate;

Systems for mixing hot mix asphalt;

Loading transfer, and storage systems associated with emission control equipment;

Fuel storage tanks; and

Stationary engines.

Review of the regulations resulted in permit conditions requiring dryers/mixers to be controlled by a 

baghouse, limiting PM emissions from the mixers/dryers to 0.04 gr/scf, limiting opacity to 20% from 

each affected emissions unit, requiring fugitive emissions to be controlled by a fugitive dust control plan, 

requiring new stationary engines to be certified to Tier standards, and requiring existing stationary 

engines to meet maintenance requirements, a 49 ppm CO at 15% O2 limit, or a 23 ppm CO at 15% O2 

limit based on engine size.

In addition, we also included conditions that fuel used in the dryer/mixer and auxiliary heaters must be 

limited to natural gas, distillate fuel, and biodiesel. The stationary engines are limited to using diesel and 

biodiesel as fuels. All liquid fuels are limited to no more than 0.0015 percent sulfur by weight. These 

conditions represent the standard fuels used for this equipment and the standard sulfur content these 

fuels must attain. 

For CO and VOC emissions, we looked at San Joaquin Valley Unified Air Pollution Control District Rule 

4309 for Dryers, Dehydrators and Ovens. Based on the limits in this rule, we set a CO emission limitation 

of 600 ppm at 3% O2 for dryers burning liquid fuels and 400 ppm @ 3% O2 for gaseous fuel. This limit 

will ensure good combustion practices for the dryers, which will also limit VOC emissions. 
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Although we reviewed the NSPS requirements for tanks, we did not include any limits in the permit as 

the tanks used by SRGCS facilities will not need to meet the control requirements of the NSPS. The 

questionnaire limits eligibility for the general permit to tanks less than 151m3that store liquids with a 

true maximum vapor pressure less than 4.0 psi. 

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 by 

HMA 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 by HMA across the country, based on the particular attainment status 

where the source is locating. As such, the chosen technologies are considered widely available and 

consideration of more cost-effective alternatives is not necessary at this time. We intend 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 Requirements

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

limitations that apply to the source. The proposed general permit requires monitoring that assures that the 

baghouse is operating properly, that opacity is observed on a weekly basis, that fugitive emissions surveys are 

conducted weekly, that a burner tune-up is required each time the source is relocated, and that stationary 

engines with oxidation catalyst monitor the inlet temperature and pressure drop. The proposed general permit 

also requires initial and continuing compliance testing.

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), the general permit also requires 

records of the amount of asphalt produced each month, baghouse inspections, visible emission surveys, 

corrective actions taken, results of corrective actions taken, results of source tests, results of the dryer/mixer 

tune-ups, maintenance activities of stationary engines, and oxidation catalyst performance data, as applicable, 

for stationary engines. 

40 CFR 49.155(a)(5) – Reporting Requirements

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.

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 of the General Permit.
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The questionnaire and the application for the HMA permit contain questions designed to limit the availability of 

this general permit to sources that have tanks that are not subject to the requirements of the following: 

Standards of Performance for Volatile Organic Liquid Storage Vessels (Including Petroleum Liquid Storage 

Vessels) for Which Construction, Reconstruction, or Modification Commenced After July 23, 1984 (NSPS, Subpart 

Kb). In the permitting documents the EPA basically specifies that facilities with tanks greater than 151 m3in 

capacity (39,890 gallons) and 27.6 kPa (4 psi) vapor pressure are ineligible for the general permit. 

Other than the production limit and fuel usage limits, the Emission Limitations and Standards section of the 

permit includes the following additional requirements which are necessary to ensure the emissions from the 

entire asphalt plant will be below the emission limitations and production limits:

(1) Exclusion of the Facilities Located in Severe and Extreme Ozone Nonattainment Areas 

The NSR major source thresholds are 10 tpy for VOC or NOX for extreme ozone nonattainment areas and are 25 

tpy for VOC or NOX for severe ozone nonattainment areas. The emission limitations for this general permit for 

facilities located in nonattainment areas are 50 tpy for VOC and NOx (see Table 5). Since this general permit is 

only applicable to NSR minor sources, facilities which have VOC or NOx emissions less than 50 tpy and are 

located in extreme or severe ozone nonattainment areas, could be NSR major sources if the PTE of the facilities 

is greater than the NSR major source thresholds of 10 or 25 tpy. Therefore, this general permit is not intended to 

cover facilities located in severe or extreme ozone nonattainment areas. The permit includes a condition 

specifying that the affected facility shall not locate or relocate to a severe or extreme ozone nonattainment 

area. 

(2) Limitations for Combustion Units 

The source definition for HMA plants includes all the combustion units on site. The most common combustion 

units include hot oil heaters, engines, and emergency generators. In order to limit the combustions emissions 

from these combustion units, the draft permit is limited to the following fuels: 

Natural gas, propane, distillate fuel, and biodiesel in the dryer/mixer and auxiliary heaters; and

Diesel and biodiesel in the stationary engines and generators. 

In addition, the total maximum heat input capacity of the auxiliary heaters must be less than 10 MMBtu/hour. 

This ensures the oil heaters at the affected facilities do not trigger the requirements of NSPS, Subpart Dc

(Standards of Performance for Small Industrial-Commercial-Institutional Steam Generating Units). These limits 

are necessary to ensure that the SO2, CO and NOX emissions from all the combustion units (including dyers, 

auxiliary heaters, and engines/generators) will not exceed the emissions limitations. 

(3) Requirements to Limit Particulate Emissions 

Particulate emissions are another concern for asphalt plants. Since asphalt plants may be subject to NSPS, 

Subpart I which was promulgated before January 1, 1980, fugitive emissions from asphalt plants must be 

included in total facility emissions for Title V and PSD major source determination purposes. Therefore, while 

considering the emissions limitations for this general permit, fugitive emissions from asphalt plants must be 

taken into account. In order to limit the particulate emissions from the asphalt plants covered by this general 

permit/permit, the draft permit includes the following additional PM control requirements:

Require the mixer/dryer be controlled by a baghouse; and

Require the facility to operate the production equipment in accordance with the Fugitive Dust Control 

Plan specified in Attachment B of this document and Attachment C of the general permit. This dust 

control plan is adopted from the General Permit for Hot Mix Asphalt Plants developed by Wisconsin.
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The above PM related requirements are necessary because the throughput limits were derived assuming that all 

the particulate emission units at the affected asphalt plants are properly controlled. 

(4) Monitoring and Testing Requirements

In order to demonstrate continuous compliance with the PM and opacity limits, the proposed general permit 

includes the following monitoring requirements:

Weekly visible emissions surveys; and

Inspections for emissions units controlled by baghouses: 

o Inspect inside the baghouse for “clean” side deposits and evidence of defective bags or leakages 

between the kiln or “dirty” side and stack or “clean” side of each baghouse used at least once 

per week when the associated emission unit is in operation; and

o Inspect and replace filter bags according to the manufacturer’s documentation or more 

frequently as indicated by weekly inspections for “clean” side deposits.

The Recordkeeping Requirements section of the permit includes necessary recordkeeping requirements to 

demonstrate compliance with the production and liquid fuel usage limits, fuel type limits, unit capacity limits, 

and records associated with the operation of control devices. The proposed general permit does not include the 

following limitations which are common in the state permits reviewed. (See Attachment A for a listing of the 

state permit requirements.) The reasons for not including these limits in this general permit are explained 

below:

Plant Capacity Limit: Some state programs include asphalt plant capacity limits (in tons/hour) and dryer 

capacity limits (in MMBtu/hour) in their general permit programs. In general, the plant capacity is 

limited to less than 700 tons/hour and the dryer capacity is limited to less than 150 MMBtu/hour. Since 

emission factors for asphalt mixer/dryers in AP-42, Chapter 11.1 for Hot Mix Asphalt Plants are in units 

of lb/ton and the emissions are calculated based on the amount of asphalt produced, the capacity of the 

asphalt plant does not determine the actual emissions from the dryer/mixer. Therefore, the draft permit 

does not include these dryer capacity limits since it is not necessary to show compliance with the 

emission and throughput limits in this general permit.

Total Fuel Usage Limit for the Dryer: Since emission factors for asphalt mixer/dryers in AP-42, Chapter 

11.1 for HMA plants are based on the amount of asphalt produced, limiting the annual production of the 

asphalt plant will effectively limit the emissions from the dryer/mixer. Limiting the amount of fuel used 

in the dryer/mixer is not necessary. Note that the definition of HMA plants in this general permit 

includes engines/generators. The CO emissions from engines/generators can be significant. Therefore, a 

total fuel usage limit for the engine/generators is necessary and has been included in the general 

permit.

4.4 Requirements for Sources Located in Nonattainment Areas

For sources located in nonattainment areas we looked at the control requirements required in other 

nonattainment areas in the country, specifically:

South Coast Air Quality Management Districts Rule 1147 for Nitrogen Oxides (NOx) Reductions from 

Miscellaneous Sources – this rule is in an ozone nonattainment area; and

South Coast Air Quality Management Districts Rule 1155 for Particulate Matter (PM) Control Devices –

this rule is in a PM10 and PM2.5 nonattainment area.
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This resulted in applying a PM limit of 0.01 gr/scf (filterable and condensable) for sources located in PM10 or 

PM2.5 nonattainment areas and a NOX limit of 40 ppm at 3% O2 for liquid fuel and 36 ppm at 3% O2 for gaseous 

fuel for sources located in ozone nonattainment areas. The other limits for attainment areas also apply to these 

sources. We did not discover any feasible control technologies or more stringent emission limits that could apply 

in CO nonattainment areas.

There are additional requirements for sources located in nonattainment areas that go beyond those found in the 

NSPS and NESHAP requirements. Since some tribes are located in ozone, PM10, PM2.5, and CO nonattainment 

areas, additional requirements for emissions from HMA plants located in nonattainment areas are necessary. 

Note that this general permit does not cover facilities located in severe or extreme ozone nonattainment areas 

or serious CO nonattainment areas. In order to develop additional requirements for HMA plants in ozone 

nonattainment areas, the EPA has reviewed the policy and procedures developed by the South Coast Air Quality 

Management District and added the following additional requirements for facilities located in nonattainment 

areas: for sources located in a serious ozone nonattainment area or located in a serious PM10 nonattainment 

area, NOX emissions from the dryers shall not exceed the limits specified in Table 3 below.

 Table 3: NOX Emission Limits for Facilities Located in Ozone, NO2, and PM2.5 Nonattainment Areas

Type of Fuel NOX Emission limitation for Dryers

Gaseous Fuel 36 ppmvd at 3% O2

Liquid Fuel 40 ppmvd at 3% O2

The NOX emission limitation specified in Table 3 for gaseous fuel was based on the Best Available Control 

Technology (BACT) determination for asphalt batch plants developed by South Coast Air Quality Management 

District (CA BACT Guidelines, Part D). The NOX emission limitation specified in Table 3 for liquid fuel was adopted 

from California Air Quality Rule for NOX Reductions from Miscellaneous Sources (CA Rule 1147). 

If located in a PM2.5 or PM10 nonattainment area, PM emissions (including both filterable and condensable PM) 

from the dryers shall not exceed 0.01 gr/dscf. This PM emission limitation is based on the PM emission limitation 

for HMA production equipment in California Air Quality Rule for Particulate Matter (PM) Control Devices (CA 

Rule 1155). 

If located in a CO nonattainment area, CO emissions from the dryers shall not exceed the limits specified in 

Table 4 below:

 Table 4: CO Emission Limits for the Facilities Located in CO Nonattainment Areas

Type of Fuel CO Emission Limitation for Dryers

Gaseous Fuel 42 ppmvd at 19% O2

(= 400 ppmvd at 3% O2)

Liquid Fuel 64 ppmvd at 19% O2 or

(= 600 ppmvd at 3% O2)

The CO emission limits in Table 4 above are adopted from the CO emission limits in California San Joaquin Valley 

Rule for Dryers, Dehydrators, and Ovens (San Joaquin Rule 4309). 
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The EPA will require performance stack testing to demonstrate compliance with the additional NOx, CO, or PM 

emission limits for the facilities located in nonattainment areas. These tests should be repeated every 5 years. 

The affected facilities are required to perform stack testing for NOx, PM and CO according to the test methods 

prescribed in 40 CFR part 60, Appendix A. 

4.5 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 HMA facility general permit, the EPA provides guidance to assist sources in

complying with these two statutes.

4.6 Additional Requirements

The EPA added a 150 foot setback requirement to the general permit for the HMA plant equipment and any 

engines from the nearest property boundary. The EPA also added a 1,000 foot setback requirement between the 

nearest residence. These requirements are similar to those included in HMA general permits for the states of 

Alaska and Washington. 

5. Emission Limitations1 and Surrogate Throughput Limits 

5.1 Developing the Surrogate Limits and Limitations

Emission limitations on production and fuel usage limits as surrogate emissions limitations were established 

below the thresholds for the major NSR and Title V permitting programs. The emission thresholds for sources 

located in attainment areas are 100 tpy, which are the thresholds for Title V operating permit program. The 

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.

In general, CO is the pollutant of concern emitted by HMA plants. Because the major source thresholds in CO 

attainment and moderate nonattainment areas are identical (100 tpy), we believe there is no reason to establish 

separate asphalt production limits as surrogates for emissions limitations in these areas. The major source 

threshold for serious CO nonattainment areas is 50 tpy. However, because there are currently no CO 

nonattainment areas in the United States, and because CO is the pollutant of concern we have decided not to 

allow coverage of the HMA General Permit in serious CO nonattainment areas at this time.

Diesel-fired internal combustion engines that generate mechanical and electrical power at HMA plants can emit 

NOx at levels high enough to make NOx a secondary pollutant of concern. For this reason, we found it necessary 

to establish fuel usage limits as surrogate emissions limitations for the engines that are part of the stationary 

source. Because the major source threshold for NOxis 50 tpy in serious ozone nonattainment areas, we found it 

necessary to establish a lower limit for HMA plants in serious ozone nonattainment areas. The fuel usage limits 

 

1

The definition of emission limitation used in this Background Document is the one provided in the Indian Country 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 12 of 27

as surrogate emissions limitations do not apply to nonroad engines, such as engines that operate mobile 

equipment (e.g., trucks and loaders) and portable engines that remain at one location for less than 12 months.

The proposed general permit includes the surrogate throughput and fuel usage limits listed in Table 6 below. 

 Table 5: Emission Rates used to Determine Emission Limitations for HMA Plants

Pollutant of 

Concern Attainment Areas Nonattainment Areas

CO 100 tpy

100 tpy

(moderate areas)

50 tpy

(serious areas)

PM10* 100 tpy

100 tpy

(moderate areas)

70 tpy

(serious areas)

PM2.5* 100 tpy 100 tpy

SO2 100 tpy 100 tpy

NOX 100 tpy

50 tpy

(serious ozone areas)

100 tpy

(marginal and moderate ozone areas)

VOC 100 tpy

50 tpy

(serious ozone areas)

100 tpy

(marginal and moderate ozone areas)

*Note: The emission limitations for these pollutants include fugitive emissions. 

The draft general permit includes the throughput limits listed in Table 6 below for HMA plants located in serious 

ozone nonattainment areas and other areas. The two production limits are set at the same levels because 

potential emissions from this source category are governed chiefly by fuel usage and not tons of asphalt 

processed. They are set at levels intended to keep the sources emissions below the emissions rates in Table 5 

(CO is the controlling pollutant; the throughput calculations are contained in Attachment C).

 Table 6: Surrogate Throughput Limits for HMA Plants

Throughput Limit Serious Ozone 

Nonattainment Areas Other Areas

Production Limit

100,000 tons/ month 

(drum mix)

33,000 tons/month 

(batch mix)

100,000 tons/month 

(drum mix)

33,000 tons/month 

(batch mix)

Fuel Usage Limit for 

Engines/Generators 2,500 gallons/month 12,500 gallons/month

5.2 Emission Limitations

Three considerations form the basis for the emission limitations for the general permit:
Page 13 of 27

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

2. What do actual emissions data from the 2008 National Emissions Inventory (NEI)2indicate 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. Therefore, the 

emissions limitations included in the proposed permit are based on the Title V major source threshold of 100 tpy 

for each criteria pollutant for HMA plants subject to this general permit and located in attainment areas. 

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

facilities located in severe and extreme ozone nonattainment areas or serious CO nonattainment areas. The NSR 

major source thresholds vary depending on the classification of the nonattainment areas. For PM10

nonattainment areas, the threshold is 70 tpy for serious areas and 100 tpy for moderate areas. For ozone 

nonattainment areas, the NSR major source thresholds are 50 tpy for VOC or NOX for serious areas and 100 tpy 

for VOC or NOX for marginal and moderate areas. The draft permit uses the same VOC and NOX thresholds as the 

emission threshold for this general permit. For CO nonattainment areas, the NSR major source threshold is 100 

tpy for moderate areas. For SO2 and PM2.5 nonattainment areas, the NSR major source thresholds are 100 tpy. 

The emission limitations established in the proposed permit are based on these NSR major thresholds.

5.2.2 Analysis of NEI Data

The EPA analyzed 2008 NEI data for existing HMA facilities across the entire U.S. to evaluate the emission 

limitations established in the general permit. Although the NEI does not include actual emissions information for 

sources in Indian Country, it reflects the actual emissions from general HMA operations in 50 states. In order to 

analyze facilities whose emissions are similar to those for sources potentially subject to the Indian Country NSR 

Rule, the EPA selected facilities for analysis with the North American Industry Classification System (NAICS) 

codes listed in Table 7. For sources with these NAICS codes, the EPA selected actual emissions3 within the ranges 

listed in Table 8.

 Table 7: NAICS Codes Selected for Asphalt Manufacturing Plants

NAICS Code Description

324121 Asphalt Paving Mixture and Block Manufacturing

324122 Asphalt Paving, Roofing, and Saturated Materials Manufacturing

 

2

For more information, go to: http://www.epa.gov/ttn/chief/net/2008inventory.html. 

3

Only point source NEI data were used for this analysis. The point source inventory does not include emissions from 

nonroad engines.
Page 14 of 27

 Table 8: Emission Ranges Selected for Asphalt Manufacturing Plants

Criteria Pollutants

PM10 PM2.5 NOX SO2 CO VOC

Attainment Area

 Min. Emissions (tpy) 5 3 10 10 10 5

 Max. Emissions (tpy) 250 250 250 250 250 250

Nonattainment Area

 Min. Emissions (tpy) 1 0.6 5 5 5 2

 Max. Emissions (tpy) 250 250 250 250 250 250

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 throughput 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 (Tribal 

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 7 and the emission ranges defined in Table 8, the EPA identified the HMA 

facilities located in attainment and nonattainment areas for NOx, VOC, PM10, PM2.5, CO and SO2. The EPA is 

providing the number of facilities (and average emissions) under the proposed emissions limitations and above 

the minor source thresholds. 

Table 9: Number of Facilities and Average Emissions for Hot Mix Asphalt Facilities Selected.

Criteria Pollutants Number of Facilities

Attainment Areas

NOx

Facilities > 10 tpy and < 100 tpy 64 (100% of facilities covered)

Average Emissions (tpy) 17

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

VOC

Facilities > 5 tpy and < 100 tpy 90 (100% of facilities covered)

Average Emissions (tpy) 9

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

PM2.5

Facilities > 3 tpy and < 100 tpy 133 (100% of facilities covered)

Average Emissions (tpy) 6

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

PM10

Facilities > 5 tpy and < 100 tpy 152 (100% of facilities covered)

Average Emissions (tpy) 11

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

CO
Page 15 of 27

Criteria Pollutants Number of Facilities

Facilities > 10 tpy and < 100 tpy 394 (100% of facilities covered)

Average Emissions (tpy) 23

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

SO2

Facilities > 10 tpy and < 100 tpy 74 (100% of facilities covered)

Average Emissions (tpy) 18

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

Nonattainment Areas

NOx (moderate)

Facilities > 5 tpy and < 100 tpy 83 (43% of facilities covered)

Average Emissions (tpy) 12

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

NOx (serious)

Facilities > 5 tpy and < 50 tpy 1 (50% of facilities covered)

Average Emissions (tpy) 5

Facilities > 50 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

VOC (moderate)

Facilities > 2 tpy and < 100 tpy 110 (55% of facilities covered)

Average Emissions (tpy) 7

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

VOC (serious)

Facilities > 2 tpy and < 50 tpy 1 (50% of facilities covered)

Average Emissions (tpy) 3

Facilities > 50 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

PM2.5

Facilities > 5 tpy and < 100 tpy 106 (74% of facilities covered)

Average Emissions (tpy) 4

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

PM10 (moderate)

Facilities > 5 tpy and < 100 tpy 6 (100% of facilities covered)

Average Emissions (tpy) 7

Facilities > 100 tpy and < 250 tpy 0

Average Emissions (tpy) N/A

PM10 (serious)

Facilities > 5 tpy and < 70 tpy 24 (92% of facilities covered)

Average Emissions (tpy) 9

Facilities > 70 tpy and < 250 tpy 0

Average Emissions (tpy) N/A
Page 16 of 27

Criteria Pollutants Number of Facilities

CO (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

CO (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

SO2

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

5.2.3 State Program Limits

The EPA researched similar types of permits developed by the states of Alaska, Arkansas, Arizona, Mississippi, 

New Mexico, Pennsylvania, South Carolina, Washington, Wisconsin, and West Virginia. The requirements for 

each state program are summarized in Attachment A. Based on the search results, most of the state general 

permits set the emission limitations to be close to 100 tpy for all criteria pollutants and the emission limits range 

from 80 tpy to 100 tpy. As a result, establishing the emissions limitations in the proposed permit using 100 tpy 

for all criteria pollutants for facilities located in attainment areas is within the range of the emission limits in the 

state programs reviewed. 

5.3 Calculating the Throughput Limits

The EPA back-calculated the production limits and fuel usage limits for the engines/generators that yielded 

emissions at the major source emission thresholds listed in Table 5. The following assumptions are adopted for 

this calculation:

The dryer is controlled by a baghouse;

All production equipment is properly operated in accordance with the fugitive dust control plan;

Natural gas, propane, distillate fuel, and biodiesel are used in the dryer;

Natural gas, propane, distillate fuel, and biodiesel are used as fuels in the auxiliary heaters;

Diesel and biodiesel are used in the engines/generators;

The sulfur content of liquid fuel is 0.0015% by weight or less; and

The total heat input capacity of all the auxiliary heaters at the affected facilities is 10 MMBtu/hour. 

Attachment C contains example calculations showing how the upper production and fuel usage limits for 

engines/generators for drum mix asphalt plants in Table 6 correspond to the upper CO emission limitation in 

attainment and nonattainment areas as shown in Table 5. (Attachment C does not include an example 

calculation for batch plants. However, the results also show that how the upper production and fuel usage limits 

for engines/generators in Table 6 correspond to the upper CO emission limitation in attainment and 

nonattainment areas as shown in Table 5 for that type of plant.) Although emissions from asphalt plants include 
Page 17 of 27

PM and all criteria pollutants, CO is the controlling pollutant of concern when developing the production and 

fuel usage limits. CO is emitted from the mixer/dryer, asphalt load-out/silo filling operations, auxiliary heaters, 

and engines/generations. 
Page 18 of 27

References:

2008 National Emission Inventory Data, U.S. Environmental Protection Agency.

http://www.epa.gov/ttn/chief/net/2008inventory.html

40 CFR 49.151 – 40 CFR 49.165, Federal Minor New Source Review (NSR) Program in Indian Country.

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=ffc06a883374e41e6772cd842b1ac2d4&tpl=/ecfrbrowse/Title40/40cfr49_main_02.tpl

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

Generating Units. 

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=4502b9bec7883393acc0ba9745803908&rgn=div6&view=text&node=40:6.0.1.1.1.12&idno=40

40 CFR Part 60, Subpar I, Standards of Performance for Hot Mix Asphalt Facilities.

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=f2c4f71bd50d2a8883adafec36732010&rgn=div6&view=text&node=40:6.0.1.1.1.20&idno=40

40 CFR Part 60, Subpar Kb, Standards of Volatile Organic Liquid Storage Vessels (Including Petroleum Liquid 

Storage Vessels) for Which Construction, Reconstruction, or Modification Commenced After July 23, 1984.

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=f2c4f71bd50d2a8883adafec36732010&rgn=div6&view=text&node=40:6.0.1.1.1.25&idno=40

40 CFR Part 60, Subpar 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&idno=40

40 CFR Part 60, Subpar JJJJ, Standards of Performance for Stationary Spark Ignition Internal Combustion Engines.

http://ecfr.gpoaccess.gov/cgi/t/text/textidx?c=ecfr&sid=f2c4f71bd50d2a8883adafec36732010&rgn=div6&view=text&node=40:6.0.1.1.1.99&idno=40

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

Combustion Engines (RICE).

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div6&view=text&node=40:13.0.1.1.1.1&idno=40

Alaska Dept. of Environmental Conservation, “Minor General Permit 3 for Asphalt Plants.” 

http://dec.alaska.gov/air/ap/docs/GP3MG3applic%204-8-10.pdf

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

CA BACT Guidelines, Part D - Best Available Control Technology Guidelines for Non-Major Polluting Facilities, 

South Coast Air Quality Management District.

http://www.aqmd.gov/bact/PartD-10-3-2008.pdf 

San Joaquin Valley Rule 4309 - Dryers, Dehydrators, and Ovens, San Joaquin Valley District, California.

http://www.valleyair.org/rules/currntrules/r4309.pdf
Page 19 of 27

South Coast Air Quality Rule 1147- NOX Reductions from Miscellaneous Sources.

http://www.aqmd.gov/rules/reg/reg11/r1147.pdf

South Coast Air Quality Rule 1151- Particulate Matter (PM) Control Devices.

http://www.aqmd.gov/rules/reg/reg11/r1151.pdf

Page 21 of 27

 Attachment A – Summary of the State Permitting Programs for HMA Plants

State Permit Type Emission Limits Production/Capacity Limits Fuel Limits Other Requirements Weblink

AK General 

Permit

PM10 < 100 tpy

NOX < 100 tpy

SO2 < 100 tpy

N/A For SO2 protection 

Area: 

1) Use diesel fuel with a 

sulfur content of ≤ 

0.075% by weight or 

use NG and

2) Diesel electric 

generators or other 

diesel engines may not 

be used. 

Setback from nearest 

residence of 330 feet, 

and 800 feet if more 

than two construction 

seasons.

http://dec.alaska.gov/air/ap/docs/GP

3MG3applic%204-8-10.pdf

AR General 

Permit

PM < 10 tpy

PM10 < 6.5 tpy

NOX < 95 tpy

CO < 95 tpy

VOC < 95 tpy

SO2 < 50 tpy

Production Limit:

< 475,000 tpy for aggregate;

and

< 100,000 tpy for recycled 

shingle.

Fuel Oil Usage Limit:

1) < 2,300,000 

gallons/year for fuel 

oils with sulfur content

< 0.5% and

2) < 1,150,000 and

gallons/year for fuel 

oils with sulfur content

< 1 %.

< 1,500 hrs/year for 

reclaimed asphalt 

pavement processing 

operations; 

dust control 

requirements; and

PM, NOx, CO, VOC and 

opacity stack testing for 

the asphalt plant (every 

5 years). 

http://www.adeq.state.ar.us/air/bra

nch_permits/pdfs/1912-AGP-000.pdf

AZ General 

Permit

< 90 tpy for all 

criteria 

pollutants

Production Limit:

< 5,280 tons/day for PM10

attainment area; and

< 3,150 tons/day for PM10 

nonattainment area.

HAP content limits for 

fuels.

Fugitive Dust Control 

Plan.

http://www.azdeq.gov/environ/air/p

ermits/download/gnhmapapp.pdf

MS Multimedia 

General 

Permit

< 100 tpy for all 

criteria 

pollutants

Production Limits:

< 360,000 tpy (batch mix);

and

< 500,000 tpy (drum mix).

Fuel Type Limit: NG, 

LPG, fuel oil, liquid bioderived fuel and waste 

oil.

Sulfur content of the 

liquid oil < 1%.

HAP content limits for 

waste oils.

N/A http://www.deq.state.ms.us/MDEQ.

nsf/pdf/epd_AsphaltGeneralPermit/$

File/01General.pdf?OpenElement
Page 22 of 27

State Permit Type Emission Limits Production/Capacity Limits Fuel Limits Other Requirements Weblink

NM

General 

Constructio

n Permit

PM < 95 tpy

NOX < 95 tpy

CO < 95 tpy

VOC < 95 tpy

SO2 < 50 tpy

Single HAP < 8 

tpy

Total HAPs < 23 

tpy

Production Limit:

< 600 tons/hour

Capacity Limit:

< 180 hp for generators.

Fuel Type Limit:

1) NG, LPG, Gasoline, 

and 

2) No. 2 fuel oil with 

sulfur content < 0.05%.

Operation Hours < 4,380 

hrs/year; and 

Fugitive Dust Control 

Plan.

http://www.nmenv.state.nm.us/aqb/

permit/Permit_Apps/Permit_Apps_4

_GCP-3.html

PA General 

Permit

PM < 0.009 

gr/dscf

PM10 < 0.021 

gr/dscf

NOX < 60 ppmvd

@15%O2 

CO < 200 ppmvd

@15%O2

VOC < 30 ppmvd

@15%O2

N/A Sulfur Content Limits:

1) ≤ 0.3% for No.2 fuel 

oil, biodiesel and 

alternative fuels;

2) ≤ 0.5% for No.4 fuel 

oil and waste-derived 

liquid fuel; and

3) HAP content limits 

for waste-derived liquid 

fuel.

Fugitive dust control 

requirements.

http://www.dep.state.pa.us/dep/dep

utate/airwaste/aq/permits/gp/Final_

General_Permit-13_Conditions.pdf

SC General 

Permit

< 100 tpy for 

criteria 

pollutants

< 10/25 for HAPs

Production Limits:

< 250 tons/hour;

< 493,515 tpy (batch mix);

and

< 1,509,015 tpy (drum mix).

Capacity Limit:

< 10 MMBtu/hour for 

heaters.

Fuel Type Limit:

NG, propane, LPG, and 

approved waste oil.

< 14 hrs/day for units 

using No. 2 fuel oil; and

< 250 hr/year for 

emergency generators.

http://www.scdhec.gov/environment

/baq/Permitting/GeneralPermits/hot

_mix_asphalt.asp
Page 23 of 27

State Permit Type Emission Limits Production/Capacity Limits Fuel Limits Other Requirements Weblink

WA

General 

Order for 

Drum Mix 

Asphalt 

Plants

CO < 80 tpy

NOX < 80 tpy

SO2 < 80 tpy

VOC < 5.76 tpy 

(BACT)

Production Limits:

< 500 tons/hour;

< 6,000 tons/day; and

< 300,000 tpy.

Capacity Limit:

< 150 MMBtu/hour for 

drum mixer/dryer.

Fuel Type Limit:

NG, LPG, and Diesel 

with sulfur content < 

0.0015%.

N/A http://www.ecy.wa.gov/programs/ai

r/AOP_Permits/Boiler/GeneralOrders

.htm

WI General 

Permit

SO2 < 80 tpy Production Limits:

< 700 tons/hour and

< 625,000 tons/month.

Total Fuel Usage < 

125,000 gallons/month

Fuel Usage for Engines 

< 14,167 gallons/month

Sulfur content of the 

fuel < 1.3%

Fuel Type Limit:

NG, propane, gasoline, 

diesel, biodiesel, and 

No. 2 through No. 6 

fuel oil. 

Fugitive Dust Control 

Plan; and

Stack Height 

Requirements.

http://dnr.wi.gov/air/pdf/HMAGOPfa

ct.pdf

WV General 

Permit

< 100 tpy for all 

criteria 

pollutants

N/A Sulfur Content Limits:

≤ 0.5% for fuel oils.

HAP content limits for 

used or recycled oils.

Fugitive dust control 

requirements and 

Storage tank capacity

limit.

http://www.dep.wv.gov/daq/permitt

ing/Documents/GeneralPermits/G20-

B%20Permit-%202009.pdf
Page 24 of 27

Attachment B

Fugitive Dust Control Plan

1. Site Roadways and Plant Yard

a. The dust on the site roadways/plant yard shall be controlled by applications of water, calcium 

chloride or other acceptable and approved fugitive dust control compound. Applications of dust 

suppressants shall be done as often as necessary to meet all applicable emission limits.

b. All paved roadways/plant yards shall be swept as needed between applications.

c. Any material spillage on roads shall be cleaned up immediately.

2. Plant

a. The drop distance at each transfer point shall be reduced to the minimum the equipment can 

achieve. 

b. The transfer point from the re-circulating belt to the feed belt shall be equipped with an 

enclosed chute.

3. Storage Piles

a. Stockpiling of all nonmetallic minerals shall be performed to minimize drop distance and control 

potential dust problems.

b. Stockpiles shall be watered on an as needed basis in order to meet the opacity limits. Also, 

equipment to apply water or dust suppressant shall be available at the site, or on call for use at 

the site, within a given operating day. 

4. Truck Traffic

a. Vehicles shall be loaded to prevent their contents from dropping, leaking, blowing or otherwise 

escaping. This shall be accomplished by loading so that no part of the load shall come in contact 

within six (6) inches of the top of any side board, side panel or tail gate; otherwise, the truck 

shall be tarped.

b. A speed limit sign of 15 miles-per-hour or lower shall be posted on site so that it is visible to 

truck traffic.

5. Corrective Actions

If corrective action needs to be taken, the permittee shall consider and use one or more of the 

following options: adjust the watering and/or sweeping frequencies, reduce drop distances, increase 

cover, and/or take other actions to reduce fugitive dust emissions.
Page 25 of 27

Attachment C: 

Emissions Calculations for 

Production Limits and Engine/Generator Fuel Usage Limits for 

Drum Mix Asphalt Plants 

Type of Mixer: Drum Mix

Emissions are estimated based on the following assumptions:

The dryer is controlled by a baghouse;

All production equipment is properly operated in accordance with the fugitive dust control plan;

Both natural gas and No. 2 fuel are used in the dryer;

Natural gas, propane, and No. 2 fuel oil are used as fuels in the auxiliary heaters;

Both gasoline and diesel are used in the engines/generators;

The sulfur content of the No. 2 fuel oil is 0.5% by weight or less; and

The total heat input capacity of all the auxiliary heaters at the affected facilities is 10 

MMBtu/hour. 

(A) Limits for Facilities Located in Areas Other Than Serious Ozone Nonattainment Areas

Production Limit: 100,000 tons per month of asphalt 

Total Fuel Usage Limit for Engines/Generators: 12,500 gallons per month

The PM and criteria pollutant emissions from all the equipment at this drum mix asphalt plants are 

summarized below (SO2 emissions were not calculated because ultra low sulfur fuel is required):

Process PM PM10 PM2.5 NOX CO VOC

Dryer/Mixer 19.8 13.8 1.74 33.0 78.00 19.20

Load-out/Silo 

Filling 0.66 0.66 0.66 - 1.48 9.66

Conveying 3.60 1.32 1.32 - - -

Screening 1.32 0.44 0.03 - - -

Storage Piles 3.43 1.62 0.25 - - -

Lime Silo Loading 4.82 4.82 4.82 - - -

Auxiliary Heater 0.63 1.03 0.80 6.26 3.61 0.48

Engine/Generator 3.19 3.19 3.19 45.32 9.76 3.70

Total Emissions 37.45 26.89 12.80 84.58 92.85 33.04

Based on the total emissions, CO is considered the pollutant of concern since it is the pollutant with 

emissions closest to the emission limitation of 100 tpy. By limiting CO to less than 100 tons per year, PM, 

PM10, PM2.5, and VOC emissions are maintained below the major source thresholds for both attainment 

and allowed nonattainment areas. The CO emissions are from the dryer/mixer, load-out/silo filling 

operations, auxiliary heaters, and engine generators. Emissions were calculated very conservatively 

assuming full utilization of 10 MMBtu auxiliary heaters for 8,760 hours per year and uses AP 42 factors 

for the dryer/mixer and the engines. The CO emissions for each of these processes are detailed below:
Page 26 of 27

1. CO Emission from the drum mix dryer/mixer

= Emission Factor x Production Limit

= 0.13 lbs/ton x 1,200,000 tpy x 1 ton/2000 lbs

= 78.0 tpy

Where the CO emission factor is from AP-42, Table 11.1-7.

2. CO Emission from the asphalt load-out operation

= Emission Factor x Production Limit

= 0.01349 lbs/ton x 1,200,000 tpy x 1 ton/2000 lbs

= 0.81 tpy

Where the CO emission factor is from AP-42, Table 11.1-14.

3. CO Emission from the asphalt silo operation

= Emission Factor x Production Limit

= 0.001109 lbs/ton x 1,200,000 tpy x 1 ton/2000 lbs

= 0.67 tpy

Where the CO emission factor is from AP-42, Table 11.1-16.

4. CO Emission from the auxiliary heaters

= Capacity Limit x Emission Factor x 8760 hr

= 10 MMBtu/hour x 1 MMSCF/1,020 MMBtu x 84 lb/MMSCF x 8760 hr/year x 1 ton/2000 lb

= 3.61 tpy

Where the CO emission factor is for NG combustion (worst case scenario among using NG, 

propane, and No. 2 fuel) and is from AP-42, Chapter 1.4.

5. CO Emission from the engine/generator

= Fuel Usage x Emission Factor

= 150,000 gallons/year x 7.1 lbs/gallon x 0.0193 MMBtu/lb x 0.95 lb/MMBtu x 1 ton/2000 lb

= 9.76 tpy

Where the CO emission factor is from AP-42, Table 3.3-1.

6. Therefore, the total CO emissions from the entire source are:

= 78.0tpy + 0.81 tpy + 0.67 ton/year + 3.61 tpy + 9.76 tpy 

= 92.85 tpy (< 95 tpy, the CO emission limitation for facilities located in attainment areas)

(B) Limits for Facilities Located in Serious Ozone Nonattainment Areas

Production Limit: 

100,000 tons per month of asphalt 

Total Fuel Usage Limit for Engines/Generators: 2,500 gallons per month
Page 27 of 27

The PM and criteria pollutant emissions from all the equipment at this drum mix asphalt plants are 

summarized below (SO2 emissions were not calculated because ultra low sulfur fuel is required):

Process PM PM10 PM2.5 NOX CO VOC

Dryer/Mixer 19.8 13.8 1.74 33.0 78.00 19.20

Load-out/Silo Filling 0.66 0.66 0.66 - 1.48 9.66

Conveying 3.60 1.32 1.32 - - -

Screening 1.32 0.44 0.03 - - -

Storage Piles 3.43 1.62 0.25 - - -

Lime Silo Loading 4.82 4.82 4.82 - - -

Auxiliary Heater 0.63 1.03 0.80 6.26 3.61 0.48

Engine/Generator 0.64 0.64 0.64 9.06 1.95 0.74

Total Emissions 34.90 24.34 10.25 48.32 85.04 30.08

Emissions were calculated in the same way as in the attainment area example above. In this case, the 

limiting pollutant is NOx. The potential to emit at full production appears to be very close to the major 

source threshold. However, this value was very conservatively calculated because it assumes full 

utilization of 10 MMBtu/hour auxiliary heaters for 8,760 hours per year, uses AP 42 factors for the dryer 

mixer where the permit requires more stringent emission limits, and uses the AP-42 emission factors for 

small diesel engines rather than the higher factors for engines > 600 hp.