CAPCOA BACT Clearinghouse Resource Manual

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XII. Glossary of Some Air Pollution Terms

Air Pollution Control Officer (APCO): The county or district officer responsible for matters of air pollution and its control. The head of the air pollution control district.

Air Quality Increment: A level to which air quality in an attainment area is allowed to degrade in siting a new or modifying an existing stationary source under the prevention of significant deterioration program. The size of the increment depends on the classification of the area (see Class I, II, and III). Degradation up to the increment is allowed only to the extent that a national ambient air quality standard is not violated.

Airborne Toxic Control Measure (ATCM): According to Section 39655(b) of the California Health and Safety Code, an airborne toxic control measure is one of the following:

         1. Recommended methods, and, where appropriate, a range of methods, that reduce, avoid or eliminate the emissions of a toxic air contaminant. Airborne toxic control measures include, but are not limited to, emission limitations, control technologies, the use of operational and maintenance conditions, closed system engineering, design, equipment, or work practice standards, and the reduction, avoidance, or elimination of emissions through process changes, substitution of materials, or other modifications. In accordance with Health and Safety Code Section 39666(a) and (d), such measures are developed and adopted by the state for toxic air contaminants.
         2. Emission standards adopted by the Environmental Protection Agency pursuant to Section 112 of the federal act (42 U.S.C. Sec. 7412) provided the state board does not find that a board- adopted airborne toxic control measure better serves the purpose of preventing adverse health effects (see Health and Safety Code Section 39658(a)(2)).

Airborne Toxic Control Measures are implemented and enforced by air pollution control districts.

Application for Certification (AFC): An application filed with the California Energy Commission for the license of an energy project. The review process is normally twelve months and assumes responsibility for all state and local environmental permitting, including review requirements of the California Environmental Quality Act.

Area Source: In the context of the federal hazardous air pollutant program, minor sources are referred to as area sources.

Authority to Construct (A/C or ATC): A name used for preconstruction permits issued by California air pollution control districts. It is synonymous with permit to construct.

Best Available Control Technology (BACT): A control technology standard used in preconstruction permit programs. The term is used in the federal prevention of significant deterioration permitting program with a definition found in the federal Clean Air Act and the Code of Federal Regulations. In California, however, it is often used to describe control technology requirements in new source review rules. Usually, definitions used by California air pollution control districts are equivalent to or even more stringent than the federal new source review requirement for control technology and more akin to the lowest achievable emission rate definition used in the federal Clean Air Act.

Best Available Retrofit Control Technology (BARCT): According to Section 40406 of the California Health and Safety Code, "an emission limitation that is based on the maximum degree of reduction achievable, taking into account environmental, energy, and economic impacts by each class or category of source." This is a control technology requirement for existing sources that is similar to but potentially more stringent than reasonably available control technology (RACT). It applies to existing sources with emissions exceeding specified thresholds. The emission thresholds vary with classification of the air quality jurisdiction, i.e., moderate, serious, severe and extreme, in accordance with criteria in the California Clean Air Act.

California Clean Air Act of 1988 (CCAA): State legislation in the form of Assembly Bill 2595 which sets up a California air quality program similar to the federal program to require, among other things, local air quality districts to develop plans for meeting state ambient air quality standards.

Class I Area: In the context of the prevention of significant deterioration program, all state air quality jurisdictions are divided into three classes of air quality protection. Class I areas are special areas of natural wonder and scenic beauty, such as national parks, national monuments, and wilderness areas, where air quality should be given special protection. Class I areas are subject to maximum limits on air quality degradation called air quality increments (often referred to as PSD increments). These air quality increments are more stringent than national ambient air quality standards (more so in Class I areas than Class II areas).

Class II Area: In the context of the prevention of significant deterioration program, all state air quality jurisdictions are divided into three classes of air quality protection. Initially, all other air quality jurisdictions were designated as Class II areas. Like Class I areas, Class II areas are subject to maximum limits on air quality degradation called air quality increments (often referred to as PSD increments). These air quality increments are more stringent than national ambient air quality standards (more so in Class I areas than Class II areas).

Class III Area: In the context of the prevention of significant deterioration program, all state air quality jurisdictions are divided into three classes of air quality protection. Initially, all non-Class I air quality jurisdictions were designated as Class II areas. Air quality jurisdictions in both of these designations are subject to maximum limits on air quality degradation called air quality increments (often referred to as PSD increments). These air quality increments are more stringent than national ambient air quality standards (more so in Class I areas than Class II areas). However, if desired by local constituents, a Class II area may be redesignated to a Class III area which has no air quality increments. In Class III areas, air quality may be degraded to levels correspondent to national ambient air quality standards.

Determination of Compliance (DOC): A document prepared by an air pollution control district that evaluates the compliance of a proposed new power plant with state and local air quality regulations. The document is very similar to a proposed decision to issue an authority to construct. It normally contains an engineering analysis and proposed permit conditions. It is submitted to the California Energy Commission and serves as a basis for permit conditions in the proposed decision for certification and compliance plan.

Discretionary Action: In the context of project review under the California Environmental Quality Act, an action where a government agency can use its judgement in deciding whether and how to carry out or approve a project.

Emission Reduction Credit (ERC): A credit for the reduction of emissions from a stationary source. Normally, emission reduction credits have formal definitions in permitting or banking rules which specify minimum criteria that an emission reduction must comply with to be approved.

Emission Offset: An emission reduction credit which is used to mitigate an increase in emissions after adjustment with required offset ratios.

Emissions Unit: According to 40 CFR 51.165(a)(1)(vi) and 40 CFR 51.666(b)(7) referring to permit requirements for NSR and PSD permitting requirements, "Emissions unit means means any part of a stationary source which emits or would have the potential to emit any pollutant subject to regulation under the Act."

Engineering Analysis: Traditionally, a document prepared to explain discretionary decisions on applications for authorities to construct. The engineering analysis documents the form of the project and assumptions regarding design and operation; demonstrates how the new source will comply with district and state air quality regulations, including control technology and mitigation requirements; and provides a basis for conditions to be included in the authorities to construct.

Engineering analyzes will now be required for Title V permitting at some California districts, also.

Environmental Impact Report (EIR): A requirement of the California Environmental Quality Act for new projects which must identify, quantify, and evaluate potential mitigation for significant effects on the environment. The draft environmental impact report is a precursor to the final environmental impact report. It is subject to public inspection and comment before it is finaled by the lead agency.

Generally Available Control Technology (GACT): Along with maximum achievable control technology (MACT), GACT is a federal control technology requirement used for hazardous air pollutants. Both MACT and GACT are used in establishing national emission standards for hazardous air pollutants (NESHAPs); however, MACT is more stringent and tends to be applied to major sources, where GACT is more likely to be applied to area sources when both major and area sources are regulated for a given source category.

Hazardous Air Pollutant (HAP): A federal term for toxic air pollutants which generally do not have safe exposure levels. An initial list of such pollutants is in Section 112(b)(1) of the federal Clean Air Act. Other compounds are added or deleted to this list as time proceeds.

Indirect Source: A source which is indirectly responsible for emission increases due to its stimulation of emission activities. An example of such a source is a new shopping center.

Initial Study: A study used by a lead agency to determine if a project potentially subject to the California Environmental Quality Act will have a potential significant effect on the environment.

Intervenor: A member of the public or governmental agency which formally files to become party to the California Energy Commission certification proceedings on a given energy project.

Lead Agency: According to Section 21067 of the California Environmental Quality Act, "the public agency which has the principal responsibility for carrying out or approving a project which may have a significant effect upon the environment."

Lowest Achievable Emission Rate (LAER): A federal control technology requirement for projects subject to new source review in nonattainment areas. According to the definition found in Section 171 of the federal Clean Air Act:

         The term "lowest achievable emission rate" means for any source, that rate of emissions which reflects --
             
(a) the most stringent emission limitation which is contained in the implementation plan of any State for such class or category of source, unless the owner or operator of the proposed source demonstrates that such limitations are not achievable, or
(b) the most stringent emission limitation which is achieved in practice by such class or category of source, whichever is more stringent.
         In no event shall the application of this term permit a proposed new or modified source to emit any pollutant in excess of the amount allowable under applicable new source standards of performance.

Major Modification: A federal term intended to refer to projects which have emissions high enough to trigger federal requirements for new source review or prevention of significant deterioration.

Major Source: A federal term used to delineate a source large enough to trigger requirements for new source review, prevention of significant deterioration, Section 112, or Title V. The definition of major source varies from program to program.

Maximum Achievable Control Technology (MACT): Along with generally available control technology (GACT), MACT is a federal control technology requirement used for hazardous air pollutants. Both MACT and GACT are used in establishing national emission standards for hazardous air pollutants (NESHAPs); however, MACT is more stringent and tends to be applied to major sources, where GACT is more likely to be applied to area sources when both major and area sources are regulated for a given source category.

Modification: The definition of modification varies from district to district. However, it is usually used as a qualitative threshold measure of when to require a new source review and permit for a previously permitted unit or facility undergoing additions or changes.

Ministerial Action: In the context of project review under the California Environmental Quality Act, an action where a governmental agency does not exercise any judgement in deciding whether and how to carry out or approve a project.

Minor Source: A source which does not qualify as a major source under any one of the federal major source definitions. The minor or major status of a source may vary depending on the context or applicable program. In the context of the federal hazardous air pollutant program. minor sources are referred to as area sources.

National Emission Standard for Hazardous Air Pollutants (NESHAP): A health-based emission standard for a hazardous air pollutant as found in Title 40, Part 61 of the Code of Federal Regulations. Since 1990 the term also includes technology-based requirements for generally available control technology (GACT) and maximum achievable control technology (MACT) as specified in Part 63.

Negative Declaration: According to Section 21064 of the California Environmental Quality Act, "a written statement briefly describing the reasons that a proposed project will not have a significant effect on the environment and does not require the preparation of an environmental impact report."

New Source Performance Standards (NSPS): National emission standards for new sources specific to certain source categories promulgated in Title 40, Part 60 of the Code of Federal Regulations.

New Source Review (NSR): A federal permitting program for new and modified sources in nonattainment areas. This program is authorized in Title I of the federal Clean Air Act under Part D.

Nonattainment Area: An air quality jurisdiction which has formally been recognized by the U.S. EPA as violating a national ambient air quality standard.

Nonattainment Area Plan: A plan generated by a local district and approved by the U.S. EPA for the purpose of attaining compliance with a national ambient air quality standard by a required date. The plan includes control measures which reduce direct and precursor emissions from existing sources. Such a plan provides a demonstration of attainment using a current emission inventory along with air quality modeling of emissions from emission inventory projects to show eventual compliance with the standard. Such plans are required for nonattainment areas under Part D, Title I of the federal Clean Air Act.

Notice of Intent (NOI): A phase of the power plant certification process which evaluates alternative sites and technologies for proposed power plants. For large power plants, this process precedes the application for certification process.

Notice of Preparation (NOP): A notification of preparation of an environmental impact report to responsible agencies by the lead agency during a project review under the California Environmental Quality Act.

Permit to Construct (P/C): Same as authority to construct.

Permit to Operate (P/O or PTO): A permit required by California districts prior to online operation of any emissions unit or, in some cases, facility, which is not exempt from permit.

Precursor: A compound chemically converted to a regulated pollutant after emission into the atmosphere.

Prevention of Significant Deterioration (PSD): A federal preconstruction permitting program that applies to areas that are not violating a National Ambient Air Quality Standard. The program applies pollutant-by- pollutant. That is, an air quality jurisdiction can be nonattainment for one pollutant and attainment or unclassified for another pollutant. The area will fall under the prevention of significant deterioration program for those pollutants that are attainment or unclassified.

Responsible Agency: According to Section 21069 of the California Environmental Quality Act, "a public agency, other than the lead agency which has responsibility for carrying out or approving a project."

Significant Effect on the Environment: According to Section 15002(g) of Chapter 3 of the Guidelines for Implementation of the California Environmental Quality Act, "a substantial adverse change in the physical conditions which exist in the area affected by the proposed project."

Small Power Plant Exemption (SPPE): An exemption from the application for certification process of the California Energy Commission available to power plants between 50 and 100 MWe in size.

Staff Assessment: An evaluation of an application for certification by the California Energy Commission staff. It is submitted to the Presiding Member and hearing office at the evidentiary hearings and becomes an important input into the Presiding Member's proposed decision on the project.

Stationary Source: In contrast to a mobile source, a source or set of sources that resides usually on a distinct piece of property. Permitting rules always provide formal definitions of the term stationary source. These definitions may vary by district and within district by permitting program.

        More formally, according to 40 CFR 165(a)(i) and 40 CFR 166(b)(5) for the NSR and PSD permitting programs, respectively, "Stationary source means any building, structure, facility, or installation which emits or may emit any air pollutant subject to regulation under the Act." In turn,

         Building, structure, facility or installation means all of the pollutant emitting activities which belong to the same industrial grouping, are located on one or more contiguous or adjacent properties, and are under the control of the same person (or persons under common control) except the activities of any vessel. Pollutant-emitting activities shall be considered as part of the same industrial grouping if they belong to the same Major Group (i.e., which have the same two-digit code) as described in the Standard Industrial Classification Manual, 1972, as amended by the 1977 Supplement (U.S Government Printing Office stock number 4101-0065 and 003-005-00176-0, respectively).

according to 40 CFR 165(a)(ii) for NSR. The same definition is used for PSD in 40 CFR 166(b)(6), except 4101-0065 is replaced with 4101-0066. California districts use similar definitions.

T-BACT: According to the Air Resources Board Risk Management Guidelines of New and Modified Sources of Toxic Air Pollutants (July 1993), "T-BACT means the most effective emissions limitation or control technique which:

         1. has been achieved in practice for such permit unit category or class of source; or
         2. is any other emissions limitation or control technique, including process and equipment changes of basic and control equipment, found by the Executive Officer or Air Pollution Control Officer to be technologically feasible for such class or category of sources, or for a specific source.

Although the definition of T-BACT does not explicitly state that cost is considered when determining T-BACT, in practice we recognize that T-BACT decisions implicitly take cost into consideration."

Title I of the Federal Clean Air Act: Among other purposes, that portion of the federal Clean Air Act which deals with air quality standards, nonattainment area plan requirements (including new source review), and prevention of significant deterioration.

Title II of the Federal Clean Air Act: Among other purposes, that portion of the federal Clean Air Act which deals with control of emissions from mobile sources.

Title III of the Federal Clean Air Act: That part of the federal Clean Air Act of 1990 that deals with, among other things, general administration of the federal Clean Air Act.

The federal hazardous air pollutant program is often referred to as the Title III program; however, all the provisions regulating hazardous air pollutants are found in Section 112 of Title I. This confusion arises due to the fact that Section 112 was amended with provisions of Title III of the federal Clean Air Act Amendments.

Title V of the Federal Clean Air Act: That part of the federal Clean Air Act which deals with requirements for operating permits.

Toxic Air Contaminant (TAC): According to Section 39655 of the California Health and Safety Code, a toxic air contaminant is "an air pollutant which may cause or contribute to an increase in mortality or in serious illness, or which may pose present or potential hazard to human health." Section 39655 also incorporates all federal hazardous air pollutants as toxic air contaminants by reference.


Best Available Control Technology (BACT) Clearinghouse Program