Antelope Valley 

Air Quality Management District 

Final 

Staff Report 

Amendment of 

Rule 218 – Stack Monitoring 

(Continuous Emission Monitoring)

and 

Adoption of 

Rule 218.1 – Continuous Emission Monitoring 

Performance Specifications

Adopted on 

July 17, 2012 

43301 DIVISION ST., SUITE 206,

LANCASTER, CALIFORNIA 93535-4649 

PHONE (661) 723-8070 

FAX (661) 723-3450 
This page intentionally left blank. 
AVAQMD Rule 218 and 218.1 TC-1

Continuous Emission Monitoring 

Final Staff Report: 08/24/12 

STAFF REPORT 

TABLE OF CONTENTS 

Rule 218 – Stack Monitoring (Continuous Emission Monitoring) and 

Rule 218.1 - Continuous Emission Monitoring Performance Specifications 

I. PURPOSE OF STAFF REPORT ........................................................................................... 1 

II. EXECUTIVE SUMMARY .................................................................................................... 1 

III. STAFF RECOMMENDATION ............................................................................................ 2 

IV. LEGAL REQUIREMENTS CHECKLIST ........................................................................... 3 

V. DISCUSSION OF LEGAL REQUIREMENTS ................................................................... 4 

A. REQUIRED ELEMENTS/FINDINGS ........................................................................... 4 

1. State Findings Required for Adoption of Rules & Regulations ...................... 4 

a. Necessity .............................................................................................. 4 

b. Authority .............................................................................................. 4 

c. Clarity ................................................................................................... 4 

d. Consistency .......................................................................................... 4 

e. Non-duplication ................................................................................... 5 

f. Reference .............................................................................................. 5 

g. Public Notice & Comment, Public Hearing ......................................... 5 

2. Federal Elements (SIP Submittals, Other Federal Submittals) ........................ 5 

a. Satisfaction of Underlying Federal Requirements ............................... 5 

b. Public Notice and Comment ................................................................ 5 

c. Availability of Document ..................................................................... 6 

d. Notice to Specified Entities ................................................................. 6 

e. Public Hearing....................................................................................... 6 

f. Legal Authority to Adopt and Implement ............................................ 6 

g. Applicable State Laws and Regulations Were Followed ..................... 6 

B. WRITTEN ANALYSIS OF EXISTING REQUIREMENTS ......................................... 7 

C. ECONOMIC ANALYSIS .............................................................................................. 7 

1. General ............................................................................................................. 7 

2. Incremental Cost Effectiveness....................................................................... 7 

D. ENVIRONMENTAL ANALYSIS (CEQA) .................................................................. 8 

E. SUPPLEMENTAL ENVIRONMENTAL ANALYSIS ................................................. 8 

1. Potential Environmental Impacts ..................................................................... 8 

2. Mitigation of Impacts ....................................................................................... 8 
TC-2 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

3. Alternative Methods of Compliance ................................................................ 9 

F. PUBLIC REVIEW .......................................................................................................... 9 

VI. TECHNICAL DISCUSSION ............................................................................................... 9 

A. SOURCE DESCRIPTION ............................................................................................. 9 

B. EMISSIONS ................................................................................................................. 10 

C. CONTROL REQUIREMENTS .................................................................................... 10 

D. PROPOSED RULE SUMMARY................................................................................. 10 

E. SIP HISTORY............................................................................................................... 16 

1. SIP History ..................................................................................................... 16 

2. SIP Analysis ................................................................................................... 17 

Appendix A – Rule 218 and 218.1 Iterated Version ....................................................................A-1 

Appendix B - Public Notice Documents ..................................................................................... B-1 

Appendix C - Public Comments and Responses ......................................................................... C-1 

Appendix D - California Environmental Quality Act Documentation ........................................D-1 

Appendix E - Bibliography .......................................................................................................... E-1 
AVAQMD Rule 218 and 218.1 1

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

STAFF REPORT 

Rule 218 – Stack Monitoring (Continuous Emission Monitoring) and 

Rule 218.1 – Continuous Emission Monitoring Performance Specifications 

I. PURPOSE OF STAFF REPORT 

A staff report serves several discrete purposes. Its primary purpose is to provide a summary and 

background material to the members of the Governing Board. This allows the members of the 

Governing Board to be fully informed before making any required decision. It also provides the 

documentation necessary for the Governing Board to make any findings, which are required by 

law to be made prior to the approval or adoption of a document. In addition, a staff report 

ensures that the correct procedures and proper documentation for approval or adoption of a 

document have been performed. Finally, the staff report provides evidence for defense against 

legal challenges regarding the propriety of the approval or adoption of the document. 

II. EXECUTIVE SUMMARY 

On July 1, 1997 the Antelope Valley Air Pollution Control District (AVAPCD) was created 

pursuant to statute (former H&S Code §40106, A.B. 266-Knight Ch. 542, statutes of 1996) and 

assumed all air pollution control responsibilities from the South Coast Air Quality Management 

District (SCAQMD) for the area of Los Angeles County outside the South Coast Air Basin 

(SCAB). The SCAQMD rules in effect within the jurisdiction of the AVAPCD remained in 

effect until the AVAPCD Governing Board superceded, amended or rescinded them. On January 

1, 2002 the AVAQMD was created pursuant to statute (H&S Code §41300 et seq.) to replace the 

AVAPCD. Once again the rules in effect at the time of the change remained in effect until the 

AVAQMD Governing Board superceded, amended or rescinded them. 

The SCAQMD adopted Rule 218 on January 9, 1976, and subsequently amended this rule on 

April 1, 1977, August 5, 1977, April 6, 1979, and August 7, 1981. The AVAPCD readopted 

Rule 218 – Stack Monitoring by statute on July 1, 1997 and the AVAQMD again readopted Rule 

218 by statute January 1, 2002. The AVAQMD subsequently amended Rule 218 on May 17, 

2005, and submitted the rule to CARB on December 7, 2005. This rule amendment was 

approved into the State Implementation Plan (SIP) at73 FR 51226 on September 2, 2008. 

Therefore, the May 17, 2005 version is the current version in the SIP. 

The AVAQMD is proposing to amend Rule 218 – Stack Monitoring (henceforth referred to by 

proposed title of Continuous Emission Monitoring) in conjunction with the amendment of Rule 

431.1 – Sulfur Content of Gaseous Fuels at the request of the United States Environmental 

Protection Agency (USEPA). Rule 431.1 will be amended in a separate action. Rule 431.1 

requires facilities burning fuel gas to comply with Rule 218. USEPA commented that in 

conjunction with the 431.1 action the AVAQMD update Rule 218 using the 1999 version of 

SCAQMD Rule 218 and 218.1 as a guide. The AVAQMD is proposing to separate the 

administrative and technical provisions of current Rule 218 into two separate rules: Rule 218 – 

Continuous Emissions Monitoring, and new Rule 218.1 – Continuous Emission Monitoring 
2 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

Performance Specifications. Amended Rule 218 specifies the administrative requirements for 

continuous emission monitoring including applicability, the application and approval process for 

continuous emission monitoring systems (CEMS), compliance dates, and record retention and 

reporting. Proposed new Rule 218.1 provides for CEMS certifications, performance 

specifications, and technical requirements for CEMS operation and maintenance. Staff has based 

the proposed rules on the May 14, 1999 version of SCAQMD Rule 218 and 218.1, per USEPA 

request. 

The amendment of Rule 218 and the adoption of new rule 218.1 was noticed for the May 15, 

2012 Governing Board meeting. This hearing was continued to the June 19, 2012 meeting and 

again to the July 17, 2012 to address comments received from USEPA requiring additional 

consultation with an affected facility. 

III. STAFF RECOMMENDATION 

Staff recommends that the Governing Board of the AVAQMD adopt, after conducting a public 

hearing, a resolution approving the amendment of Rule 218 – Continuous Emission Monitoring

and the adoption of new Rule 218.1 – Continuous Emission Monitoring Performance 

Specifications. The amendment of Rule 218 and the adoption of Rule 218.1 are necessary to 

address the request of USEPA to update the technical and quality assurance requirements for 

continuous emission monitors in conjunction with the amendment of Rule 431.1 – Sulfur 

Content of Gaseous Fuels. Rule 431.1 is proposed for amendment in a separate action. 

The Governing Board of the Antelope Valley Air Quality Management District amended Rule 

218 – Continuous Emission Monitoring and adopted new Rule 218.1 – Continuous Emission 

Monitoring Performance Specifications July 17, 2012. 
AVAQMD Rule 218 and 218.1 3

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

IV. LEGAL REQUIREMENTS CHECKLIST 

The findings and analysis as indicated below are required for the procedurally correct amendment 

of Rule 218 – Continuous Emission Monitoring and the adoption of new Rule 218.1 – 

Continuous Emission Monitoring Performance Specifications. Each item is discussed, if 

applicable, in Section V below. Copies of documents are included in the appropriate Appendix. 

FINDINGS REQUIRED FOR 

RULES & REGULATIONS

X Necessity 

 

X Authority 

X Clarity 

X Consistency 

X Non-duplication 

X Reference 

X Public Notice & Comment 

X Public Hearing 

REQUIREMENTS FOR STATE 

IMPLEMENTATION PLAN 

SUBMISSION (SIP):

X Public Notice & Comment 

X Availability of Document 

X Notice to Specified Entities (State, Air 

Districts, USEPA, Other States) 

X Public Hearing 

X Legal Authority to adopt and implement the 

document. 

X Applicable State laws and regulations were 

followed. 

ELEMENTS OF A FEDERAL 

SUBMISSION

X Elements as set forth in applicable Federal law or 

regulations. 

CALIFORNIA ENVIRONMENTAL QUALITY ACT 

REQUIREMENTS (CEQA): 

N/A Ministerial Action 

X Exemption 

N/A Negative Declaration 

N/A Environmental Impact Report 

X Appropriate findings, if necessary. 

N/A Public Notice & Comment 

SUPPLEMENTAL ENVIRONMENTAL 

ANALYSIS (RULES & REGULATIONS ONLY):

X Environmental impacts of compliance. 

N/A Mitigation of impacts. 

N/A Alternative methods of compliance. 

OTHER: 

X Written analysis of existing air pollution control 

requirements 

N/A Economic Analysis 

X Public Review 
4 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

V. DISCUSSION OF LEGAL REQUIREMENTS 

A. REQUIRED ELEMENTS/FINDINGS 

This section discusses the State of California statutory requirements that apply to the 

proposed amendment of Rule 218 – Continuous Emission Monitoring and the adoption of 

new Rule 218.1 – Continuous Emission Monitoring Performance Specifications. These 

are actions, that need to be performed, and/or information, that must be provided in order 

to amend/adopt the rules in a procedurally correct manner. 

1. State Findings Required for Adoption of Rules & Regulations: 

Before adopting, amending, or repealing a rule or regulation, the AVAQMD 

Governing Board is required to make findings of necessity, authority, clarity, 

consistency, non-duplication, and reference based upon relevant information 

presented at the hearing. The information below is provided to assist the 

AVAQMD Governing Board in making these findings. 

a. Necessity: 

The proposed amendment of Rule 218 and the adoption of new Rule 218.1 

are necessary to address the USEPA request that the technical and quality 

assurance requirements of these rules be updated in conjunction with the 

amendment of Rule 431.1 – Sulfur Content in Gaseous Fuels. Rule 431.1 

is proposed for amendment in a separate action. 

b. Authority: 

AVAQMD has the authority pursuant to California Health and Safety 

Code (H&S Code) §40702 to adopt, amend or repeal rules and regulations. 

c. Clarity: 

The proposed amendments to Rule 218 and proposed new Rule 218.1 are 

clear in that they are written so that the persons subject to the rules can 

easily understand the meaning. 

d. Consistency: 

The proposed amendments to Rule 218 and the adoption of proposed new 

Rule 218.1 are in harmony with, and not in conflict with or contradictory 

to, any state law or regulation, federal law or regulation, or court decisions 

because they update these rules to choose either the standards and 

specifications according to the provisions of proposed new Rule 218.1, or 

the applicable provisions of 40 CFR 60 Appendix B – Performance 

Specifications and Appendix F – Quality Assurance Procedures. 
AVAQMD Rule 218 and 218.1 5

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

e. Non-duplication: 

The proposed amendments of Rule 218 and adoption of proposed new 

Rule 218.1 do not impose the same requirements as an existing state or 

federal law or regulation. The District is adopting the amendments to Rule 

218 and proposed new Rule 218.1 in response to USEPA comments and 

recommendations. 

f. Reference: 

AVAQMD has the authority pursuant to H&S Code §40702 to adopt, 

amend or repeal rules and regulations. 

g. Public Notice & Comment, Public Hearing: 

Notice for the public hearing for the proposed amendment of Rule 218 and 

proposed adoption of Rule 218.1 was published April 2, 2012 for the May 

15, 2012 Governing Board meeting. This hearing was continued to the 

June 19, 2012 meeting and again to the July 17, 2012 meeting to address 

comments received from USEPA requiring additional consultation with an 

affected facility. See Appendix “B” for a copy of the public notice. See 

Appendix C for copies of comments, if any, and AVAQMD responses. 

2. Federal Elements (SIP Submittals, Other Federal Submittals). 

Submittals to USEPA are required to include various elements depending upon 

the type of document submitted and the underlying Federal law which requires the 

submittal. The information below indicates which elements are required for the 

proposed amendment of Rule 218 and the adoption of Rule 218.1 and how they 

were satisfied. 

a. Satisfaction of Underlying Federal Requirements: 

The proposed amendments to Rule 218 and the adoption of proposed new 

Rule 218.1 are subject to all the requirements for a SIP submittal because 

Rule 218 and Rule 218.1 will be included in the AVAQMD SIP. USEPA 

comments directed the AVAQMD to update Rule 218 using SCAQMD 

Rules 218 and 218.1 as amended in 1999 as a guide. These SCAQMD 

rules were SIP approved at 75 FR 32293 (June 8, 2010). The criteria for 

determining completeness of SIP submissions are set forth in 40 CFR Part 

51, Appendix V, 2.0. 

b. Public Notice and Comment: 

Notice for the public hearing for the proposed amendment of Rule 218 and 

proposed adoption of Rule 218.1 was published April 2, 2012 for the May 
6 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

15, 2012 Governing Board meeting. This hearing was continued to the 

June 19, 2012 meeting and again to the July 17, 2012 meeting to address 

comments received from USEPA requiring additional consultation with an 

affected facility. See Appendix “B” for a copy of the public notice. 

c. Availability of Document: 

Copies of proposed amended Rule 218 and proposed new Rule 218.1 and 

the accompanying draft staff report were made available to the public on 

April 2, 2012. 

d. Notice to Specified Entities 

Copies of proposed amended Rule 218 and proposed new Rule 218.1 and 

the accompanying draft staff report were mailed to all affected agencies, 

including but not limited to CARB and USEPA on April 2, 2012. 

e. Public Hearing: 

Notice for the public hearing for the proposed amendment of Rule 218 and 

proposed adoption of Rule 218.1 was published April 2, 2012 for the May 

15, 2012 Governing Board meeting. This hearing was continued to the 

June 19, 2012 meeting and again to the July 17, 2012 meeting to address 

comments received from USEPA requiring additional consultation with an 

affected facility. 

f. Legal Authority to Adopt and Implement: 

The AVAQMD has the authority pursuant to H&S Code §40702 to adopt, 

amend, or repeal rules and regulations and to do such acts as may be 

necessary or proper to execute the duties imposed upon the AVAQMD. 

g. Applicable State Laws and Regulations Were Followed: 

Public notice and hearing procedures pursuant to H&S Code §§40725-

40728 have been followed. See Section (V)(A)(1) above for compliance 

with state findings required pursuant to H&S Code §40727. See Section 

(V)(B) below for compliance with the required analysis of existing 

requirements pursuant to H&S Code §40727.2. See Section (V)(C) for 

compliance with economic analysis requirements pursuant to H&S Code 

§40920.6. See Section (V)(D) below for compliance with provisions of 

the California Environmental Quality Act (CEQA). 
AVAQMD Rule 218 and 218.1 7

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Final Staff Report: 08/24/12

B. WRITTEN ANALYSIS OF EXISTING REQUIREMENTS 

H&S Code §40727.2 requires air districts to prepare a written analysis of all existing 

federal air pollution control requirements that apply to the same equipment or source type 

as the rule proposed for modification by the District. The proposed amendment of Rule 

218 and the adoption of new Rule 218.1 are necessary to address the USEPA request that 

the technical and quality assurance requirements of these rules be updated in conjunction 

with the amendment of Rule 431.1 – Sulfur Content in Gaseous Fuels. Therefore the 

preparation of a written analysis of existing pollution control requirements that apply to 

the same equipment or source type is not required. 

C. ECONOMIC ANALYSIS 

1. General 

The amendment of Rule 218 and the adoption of new Rule 218.1 will update the 

technical and quality assurance requirements of these rules at the request of USEPA. 

There is only one source in the District that is currently subject to the requirements of 

Rule 218 (Lockheed Martin Aeronautics Company, Palmdale). This facility is already 

subject to the provisions of 40 CFR 60 Appendix B and F pursuant to permit conditions. 

The economic impacts of the amendment of Rule 218 and the adoption of new Rule 

218.1 are expected to be insignificant to this facility since it is already subject to of the 

provisions of 40 CFR 60 Appendix B and F. Lockheed Martin has indicated that they 

are able to be in compliance with the provisions of these rules upon adoption. 

The City of Palmdale is proposing to build two combustion turbine generators at the 

Palmdale Hybrid Power Project. Each Turbine is a natural gas fueled, General Electric, 

7FA combustion turbine generator block, producing approximately 255 MW(e) with a 

connected heat recovery steam generator and a steam condensing turbine, with 

maximum turbine heat input of 1736.4 MMBtu/hr. These CEMS will be subject to the 

proposed requirements of the rule. The economic impacts of the amendment of Rule 

218 and the adoption of new Rule 218.1 are expected to be insignificant to this facility 

since it is already subject to of the provisions of 40 CFR 75 and 40 CFR 60 Appendix B 

and F. 

Waste Management operates two landfills, Lancaster Landfill and Antelope 

Valley Recycling and Disposal. Each landfill is subject to the provisions of Rule 

431.1, which does require CEMS, CFGMS, or an alternative monitoring system. 

Both landfills have an approved alternative monitoring method in lieu of CEMS 

for the gas flaring system, and therefore should not be affected by the provisions 

of these rules. 

2. Incremental Cost Effectiveness 

Pursuant to H&S Code §40920.6, incremental cost effectiveness calculations are 

required for rules and regulations which are adopted or amended to meet the 
8 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

California Clean Air Act requirements for Best Available Retrofit Control 

Technology (BARCT) or “all feasible measures” to control volatile compounds, 

oxides of nitrogen or oxides of sulfur. 

The proposed amendment of Rule 218 and the adoption of new Rule 218.1 are not 

subject to incremental cost effectiveness calculations because this rule does not 

impose BARCT or “all feasible measures”. 

D. ENVIRONMENTAL ANALYSIS (CEQA) 

Through the process described below, it was determined that a Notice of Exemption 

would be the appropriate CEQA process for the proposed amendment of Rule 218 and the 

adoption of new Rule 218.1. 

1. The proposed amendment of Rule 218 and the adoption of new Rule 218.1 

meet the CEQA definition of “project.” The proposed project will provide 

procedural clarity for review and approval of CEMS, and delineate CEMS 

installation and testing requirements to facilitate compliance with 

applicable regulations. They are not “ministerial” actions. 

2. The proposed amendment of Rule 218 and the adoption of new Rule 218.1 

are exempt from CEQA review because these rules will have no 

significant effect on emissions or emission limits and will merely provide 

procedural clarity to an existing administrative rule. The improvements in 

the technical and quality assurance requirements of these rules are more 

stringent than the current existing requirements, and there is no potential 

that the amendment/adoption might cause the release of additional air 

contaminants or create any adverse environmental impacts. Therefore, a 

Class 8 categorical exemption (14 Cal. Code Reg. §15308) applies. 

E. SUPPLEMENTAL ENVIRONMENTAL ANALYSIS 

1. Potential Environmental Impacts 

The proposed amendment of Rule 218 and the adoption of Rule 218.1 do not 

have any potential environmental impacts because these rules are administrative 

in nature and specify CEMS approvals, standards, specifications and 

requirements. Therefore, these rules do not have any impact upon emissions of 

air contaminants. 

2. Mitigation of Impacts 

N/A 
AVAQMD Rule 218 and 218.1 9

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

3. Alternative Methods of Compliance 

N/A 

F. PUBLIC REVIEW 

See Staff Report Section (V)(A)(1)(g) and (2)(b), as well as Appendix B. 

VI. TECHNICAL DISCUSSION 

A. SOURCE DESCRIPTION 

Rule 218 and 218.1 will apply to all sources for which CEMS are required in District 

regulations or permit conditions, except as exempted. Exemptions from these rules 

include: CEMS subject to Regulation IX – Standards of Performance for New Stationary 

Sources, Regulation X – National Emissions Standards for Hazardous Air Pollutants, or 

Rule 3010 – Acid Rain Provisions of Federal Operating Permits; CEMS subject to 

permit conditions where the purpose of the CEMS is to monitor the performance of the 

basic and/or control equipment and not to determine compliance with any applicable limit 

or standard or; CEMS where alternative performance specifications are required by 

another District rule. Examples where Rule 218 and 218.1 apply are CEMS required 

under Rule 1110.2 – Emissions From Stationary, Non-road & Portable Internal 

Combustion Engines, Rule 1134 – Stationary Gas Turbines, Rule 1135 – Emissions Of 

Oxides Of Nitrogen From Electric Power Generating Systems, and Rule 1146 – 

Emissions of Oxides Of Nitrogen From Industrial, Institutional, And Commercial Boilers, 

Steam Generators, And Process Heaters. 

Currently, there is one operating CEMS unit in the District located at Lockheed Martin 

Aeronautics Company, Palmdale. The CEMS is a permit requirement (permit number 

B006436) for Boiler No. 3 (Plant 10, Building 603), a 96 million Btu/hr boiler. Lockheed 

has indicated verbally that they will be in compliance with these rules at the time of 

adoption. 

The City of Palmdale is proposing to build two combustion turbine generators at the 

Palmdale Hybrid Power Project. Each Turbine is a natural gas fueled, General Electric, 

7FA combustion turbine generator block, producing approximately 255 MW(e) with a 

connected heat recovery steam generator and a steam condensing turbine, with maximum 

turbine heat input of 1736.4 MMBtu/hr. These CEMS will be subject to the proposed 

requirements of the rule. 

Waste Management operates two landfills, Lancaster Landfill and Antelope Valley 

Recycling and Disposal. Each landfill is subject to the provisions of Rule 431.1, which 

does require CEMS, CFGMS, or an alternative monitoring system. Both landfills have an 

approved alternative monitoring method in lieu of CEMS for the gas flaring system. 
10 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

B. EMISSIONS 

Rule 218 and 218.1 are administrative rules, and as such will have no significant effect on 

emissions or emission limits and will merely provide procedural clarity to an existing 

rule. The improvements in the technical and quality assurance requirements of these 

rules are more stringent than the current existing requirements, and there is no potential 

that the amendment/adoption might cause the release of additional air contaminants or 

create any adverse environmental impacts. 

C. CONTROL REQUIREMENTS 

Rule 218 and 218.1 are administrative rules specifying CEMS approvals, standards, 

specifications and requirements, and do not impose any control requirements. 

D. PROPOSED RULE SUMMARY 

This section gives a brief overview of the proposed amendments to Rule 218 and 

proposed new Rule 218.1. 

The District is proposing to divide the administrative and technical provisions of the 

current version of Rule 218 into two separate rules, amended Rule 218 – Continuous 

Emission Monitoring and new Rule 218.1 – Continuous Emission Monitoring 

Performance Specifications. Amended Rule 218 defines the applicability and specifies 

the administrative requirements for continuous emission monitoring including the 

application and approval process for CEMS, the option to choose alternative performance 

specifications, compliance dates, and record retention and reporting. New Rule 218.1 

specifies CEMS certification, performance specifications, and technical requirements for 

CEMS operation and maintenance. Proposed amendments to Rule 218 will delete 

obsolete language, clarify administrative requirements, and delete the CEMS performance 

specifications in the rule. Proposed new Rule 218.1 will revise and identify these CEMS 

performance specifications to meet District requirements for approval. 

Rule 218 and 218.1 will apply to all sources for which CEMS are required in District 

regulations or permit conditions, except as exempted. Exemptions from these rules 

include: CEMS subject to Regulation IX – Standards of Performance for New Stationary 

Sources, Regulation X – National Emissions Standards for Hazardous Air Pollutants, or 

Rule 3010 – Acid Rain Provisions of Federal Operating Permits; CEMS subject to 

permit conditions where the purpose of the CEMS is to monitor the performance of the 

basic and/or control equipment and not to determine compliance with any applicable limit 

or standard or; CEMS where alternative performance specifications are required by 

another District rule. 

USEPA recommended that the AVAQMD use the 1999 version of SCAQMD Rule 218 

and 218.1 as a guide in updating the technical and quality assurance requirements of 

AVAQMD Rule 218. The proposed amendments to Rule 218 and proposed new Rule 
AVAQMD Rule 218 and 218.1 11

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

218.1 closely reflect the SCAQMD versions, with minor changes necessary for these 

rules to function properly in the AVAQMD.1

Rule 218 Overview 

Rule 218 has been reformatted to standard District format. 

Section (A) – General 

This rule applies to all CEMS that are required or specified in District rules and 

regulations including permit conditions. Examples are CEMS required under Rule 

1110.2 – Emissions From Stationary, Non-road & Portable Internal Combustion 

Engines, Rule 1134 – Stationary Gas Turbines, Rule 1135 – Emissions Of Oxides Of 

Nitrogen From Electric Power Generating Systems, and Rule 1146 – Emissions of 

Oxides Of Nitrogen From Industrial, Institutional, And Commercial Boilers, Steam 

Generators, And Process Heaters. 

This rule exempts CEMS subject to Regulation IX – Standards of Performance for New 

Stationary Sources, Regulation X – National Emissions Standards for Hazardous Air 

Pollutants, or Rule 3010 – Acid Rain Provisions of Federal Operating Permits, or to 

permit conditions where the purpose of the CEMS is to monitor the performance of 

basic and/or control equipment and not to determine compliance with any applicable 

limit or standard. This rule shall not apply where alternative performance specifications 

are required by another District rule. 

Previously, Rule 218 had no applicability within the boundaries of the AVAQMD, 

because there were no sources subject to the applicability limits. The proposed 

amendments of Rule 218 will make several facilities subject to the amended 

applicability, as there are several sources with CEMS required by permit condition. It is 

not anticipated that there will be any additional requirements for these sources, as the 

permit conditions already specify CEMS meeting the requirements of 40 CFR 60 

Appendix B and F. 

Section (B) – Definitions 

Definitions have been relocated from former Section (G) to conform to standard District 

format. 

New definitions are from SCAQMD Rule 218 unless otherwise noted. All terms related 

to the performance specifications and technical requirements have been relocated to 

proposed new Rule 218.1. New definitions include: Analyzer (previously part of Stack 

Monitoring System definition); Certified CEMS; Continuous Emissions Monitoring 

 

1

Please refer to the South Coast Air Quality Management District Staff Report for Proposed Amended Rule 218 – 

Continuous Emission Monitoring and Proposed Rule 218.1 – Continuous Emission Monitoring Performance Specifications, 

1999 (attachment H, May 14, 1999 Governing Board Agenda Item No. 35)
12 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

System (CEMS); Continuous Monitoring; Data Acquisition System (DAS); Laboratory 

Approval Program (LAP); Modification Requiring Recertification; Quality 

Assurance/Quality Control (QA/QC) Plan; Semi-Continuous Emission Monitoring; 

Semi-Continuous Emission Monitoring System (SCEMS); South Coast Air Quality 

Management District (SCAQMD); Time-Sharing; Working Day; and, Zero Check. 

Definitions that have been removed: Calibration Drift; Calibration Error; Calibration 

Gas; Ninety-Five Percent Confidence Interval; Operational Period; Parts Per Million; 

Reference Method; Relative Accuracy; Response Time; Span Cell; Stack Monitoring 

System, or Monitoring System; Use Factor; Zero Calibration Reflector; and, Zero Drift. 

Section (C) – Monitoring Requirements for New, Modified and Existing CEMS 

The owner or operator of any equipment subject to this rule shall provide, properly 

install, operate and maintain in calibration and, in good working order a certified CEMS 

to measure concentration and/or emission rates, as applicable, of air contaminants and 

diluent gases, flow rates, and other required parameters. The necessary records and 

other data necessary to calculate air contaminant emission rates shall be provided as 

specified in Sections (F) and (G). 

Section (D) – Requirements for New and Modified CEMS and SCEMS 

This section provides a schedule for the application and approval of CEMS and 

SCEMS. The application shall specify if the CEMS shall be reviewed and certified 

according to the provisions of Rule 218.1 or the applicable provisions of 40 CFR 60, 

Appendix B and F. It is specified that CEMS or SCEMS shall be certified as configured 

for normal operation. It is also specified that CEMS/SCEMS electing the performance 

specifications of Rule 218.1 shall submit a QA/QC plan. 

Section (E) – Requirements for Existing CEMS and SCEMS 

CEMS and SCEMS installed and given approval prior to the amendment of this rule 

must meet the requirements of Rule 218 Section C – Monitoring Requirements for New, 

Modified and Existing CEMS, Section F – Retention of Records for New, Modified and 

Existing CEMS and SCEMS, Section G - Reporting Requirements for New, Modified 

and Existing CEMS and SCEMS, and Section H - Posting of Written Approval for 

New, Modified and Existing CEMS and SCEMS. These units shall also meet the 

requirements of Rule 218.1 Section D – Standard for Existing CEMS and Section E – 

Standards, Specifications and Requirements for New, Modified and Existing CEMS. 

A CEMS or SCEMS application for initial and final approval submitted prior to the 

amendment of this rule shall be reviewed and approved according to the specifications 

and requirements of Rule 218.1 Section D – Standard for Existing CEMS and Section E 

– Standards, Specifications and Requirements for New, Modified and Existing CEMS. 

After final approval, the CEMS shall be operated and maintained according to the 

provisions of Rule 218 Section C – Monitoring Requirements for New, Modified and 
AVAQMD Rule 218 and 218.1 13

Continuous Emission Monitoring 

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Existing CEMS, Section F – Retention of Records for New, Modified and Existing 

CEMS and SCEMS, Section G - Reporting Requirements for New, Modified and 

Existing CEMS and SCEMS, and Section H - Posting of Written Approval for New, 

Modified and Existing CEMS and SCEMS. These units shall also meet the 

requirements of Rule 218.1 Section D – Standard for Existing CEMS and Section E – 

Standards, Specifications and Requirements for New, Modified and Existing CEMS. 

CEMS and SCEMS requiring recertification shall be reviewed and approved according 

to the applicable provisions of Rule 218.1 or 40 CFR 60 Appendix B and F. 

This section has been removed. Lockheed has indicated that they are compliant with the 

provisions of the rule and the additional time provision is not necessary. Existing 

CEMS will be allowed seven (7) years from the date of amendment to comply with the 

provisions of Rule 218 and 218.1. This requirement may be waived for a period of 

three (3) years if the owner or operator demonstrates that the CEMS is providing data of 

a quality commensurate with the original performance specifications and other 

indicators of consistent data quality. The owner or operator may reapply for the waiver 

every three (3) years under certain conditions. 

The owner or operator of an existing CEMS shall develop and implement a written 

QA/QC plan no later than one (1) year from the date of rule amendment. 

This section has been removed. Lockheed has indicated that they are compliant with the 

provisions of the rule and the additional time provision is not necessary. On or before 

six (6) years from the date of the rule amendment, the owner or operator of any existing 

CEMS shall submit either: a signed certification by an authorized representative; an 

application for CEMS modification; or, an application for waiver. 

The owner or operator of an existing SCEMS operating on or before the date of the rule 

amendment shall be required to comply with the provisions of Rule 218.1 Section (F) – 

Time-Sharing requirements, Section (C) – Standards for New or Modified CEMS, and 

Section (E) – Standards, Specifications and Requirements for New, Modified and 

Existing CEMS, or 40 CFR 60 Appendix B and F as applicable when the equipment 

served by the time-shared SCEMS is modified such that: one or more of the sources 

monitored requires a new monitoring range; the operating permit is modified to require 

continuous monitoring; or, an applicable source specific rule is adopted or revised to 

require continuous monitoring. 

Section (F) – Retention of Records for New, Modified and Existing CEMS and SCEMS 

Records shall be maintained for five (5) years. This is a change from the SCAQMD 

rule, and was made pursuant to USEPA recommendation in the USEPA Region IX TSD 

for SCAQMD Rule 218, March 18, 2010. 
14 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

Section (G) – Reporting Requirements for New, Modified and Existing CEMS and SCEMS 

Every six (6) months, the owner or operator of a CEMS shall provide a summary of the 

concentration and/or emission rate data, as applicable, obtained from the CEMS, as well 

as any additional information specified by the APCO, to evaluate the accuracy and 

precision of the measurements. More frequent reporting may be required. The 

summary report shall be submitted 30 days following the period being reported. The 

summary shall be maintained on-site in a retrievable and readable form and made 

available to the APCO upon request. 

Any concentration level and/or emission rate in excess of the regulated limit shall be 

reported within 24 hours or the next working day. The report shall include specified 

information. 

In the event of system failure or shutdown that exceeds 24 hours, the APCO shall be 

notified within 24 hours or the next working day. Compliance with Section (C) - 

Monitoring Requirements for New, Modified and Existing CEMS will be waived for 96 

hours in the event of CEMS failure or shutdown. This waiver may be extended if a 

petition for an interim variance is filed pursuant to Regulation V – Procedures Before 

the Hearing Board and shall terminate at the time the hearing board acts upon such 

variance petition. 

Regularly scheduled CEMS maintenance shall be deferred until the report is made 

following a concentration level or emission rate in excess of the regulated limit. 

Continuous emission monitoring requirements shall not apply during regular calibration 

checks of the system, or routine maintenance and repair lasting 60 minutes or less. 

Section (H) – Posting of Written Approval for New, Modified and Existing CEMS and SCEMS 

Minor clarification has been made to reference Rule 206 requirements, as well as safe 

accessibility. 

Rule 218.1 Overview 

Rule 218.1 has been formatted to standard District format. 

Section (A) – General 

Proposed new Rule 218.1 provides for the performance specification standards for new, 

modified and existing CEMS as required by the applicability of Rule 218. The 

standards for existing CEMS, which have been removed from Rule 218 and 

incorporated into Rule 218.1, have been made with minor revisions for technical 

clarification. The proposed rule also includes each equation(s) necessary to calculate for 

CEMS performance that corresponds to each standard specification. 
AVAQMD Rule 218 and 218.1 15

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Section (B) – Definitions 

To provide technical clarity and applicability, the definitions for the following have 

been deleted (or duplicated) from Rule 218, revised and incorporated into Rule 218.1: 

Analyzer; Calibration Drift; Calibration Error; CEMS; Certified Gas Mixture; 

Confidence Coefficient; Data Recorder; Full Span Range; Relative Accuracy; Relative 

Accuracy Audit; Relative Accuracy Test Audit; Sampling Interface; and, Zero Drift. 

Additional definitions provided are: CEMS Availability Percentage; Continuous 

Monitoring; Operational Period; Quality Assurance/Quality Control Plan; Modification 

Requiring Recertification; and, Linearity Error. 

Section (C) – Standards for New or Modified CEMS 

Standards that apply to new and modified CEMS include specifications and 

requirements for installation and sample location, certification tests, relative accuracy 

tests and the performance specifications for the subsequent operation and maintenance 

of the installed CEMS after District certification. A CEMS meeting these standards is 

considered capable of providing quality assured data for compliance purposes. 

Section (D) – Standards for Existing CEMS 

Standards that apply to existing CEMS include operational requirements and 

performance specifications, as well as the standards, specifications and requirements for 

new, modified and existing CEMS in the following Section (E). 

Section (E) – Standards, Specifications and Requirements for New, Modified and 

Existing CEMS 

Standards, specifications and requirements for new, modified and existing CEMS cover 

calibration gas and zero gas criteria. 

Section (F) – Time-Sharing Requirements 

Time-shared CEMS for which application is submitted after the date of rule adoption 

shall meet all performance standards listed. 

Table 1 – The official test methods employed by the District to determine compliance with the 

rules or permit conditions. 

Attachment A – Supplemental and alternative CEMS performance standards 
16 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

E. SIP HISTORY 

1. SIP History. 

Prior to 1975 the original air district for the Antelope Valley region was the Los Angeles 

County APCD that had jurisdiction covering the entire county of Los Angeles. In 1975, 

the Southern California Air Pollution Control District (So. Cal. APCD) was created by a 

Joint Powers Agreement (JPA) between Los Angeles, Orange, Riverside and San 

Bernardino Counties to replace the previous countywide air pollution control districts 

for those counties. The So. Cal. APCD adopted rule 218 on January 9, 1976. On 

February 1, 1977, pursuant to statute (Cal. Stats. 1976, Ch 324 p. 815), the South Coast 

Air Quality Management District (SCAQMD) was created with an initial jurisdiction 

that only included areas of Los Angeles, Orange, Riverside and San Bernardino 

Counties contained within the South Coast Air Basin (SCAB). Outlying areas remained 

under the So. Cal. APCD (The legislation was thereafter amended to allow non-SCAB 

areas to “opt in”. Los Angeles County exercised this option and thus the Antelope 

Valley became a part of SCAQMD). Also on February 1, 1977 the California Air 

Resources Board (CARB) issued Executive Order G-73 (1977) which adopted a “rule 

book” for those non-SCAB areas of Los Angeles, Riverside and San Bernardino 

Counties. CARB submitted the G-73 rulebook on behalf of the “county” districts and 

these rule books included Rule 218. By its terms Executive Order G-73 (1977) was 

only effective until the non-SCAB areas took other action. On February 22, 1977 the 

JPA forming the So. Cal. APCD was formally dissolved. By the terms of the JPA upon 

dissolution each county would regain its county air pollution control district with a 

jurisdiction of the non-SCAB areas of the county and the applicable rules being the So. 

Cal. APCD’s rules in effect upon the date of dissolution. Thus, as of February 22, 1977 

the version of Rule 218 for the SCAQMD reverted from the G-73 (1977) CARB version 

back to the original So. Cal. APCD September 3, 1976 version. Between 1976 and 

1997 Rule 218 was amended numerous times by SCAQMD. Specifically, it was 

amended on April 1, 1977, August 5, 1977, April 6, 1979, and August 7, 1981. 

On July 1, 1997 the Antelope Valley Air Pollution Control District (AVAPCD) replaced 

the SCAQMD as the agency with jurisdiction over the Los Angeles County portion of 

the Mojave Desert Air Basin (MDAB). Pursuant to the statutory change, the rules and 

regulations of the predecessor district were retained until the Governing Board adopted, 

amended or rescinded them. At its first meeting the AVAPCD reaffirmed all the 

existing rules and regulations thus the version in effect at the time of the change was the 

August 7, 1981 version. 

On January 1, 2002 the AVAPCD was replaced by the AVAQMD. Once again, 

pursuant to statute, the rules in effect were retained until the Governing Board adopted, 

amended, or rescinded. Similarly, at the first meeting of the AVAQMD, the Governing 

Boards reaffirmed all the rules and regulations in effect at the time the agency changed. 
AVAQMD Rule 218 and 218.1 17

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The AVAQMD most recently amended Rule 218 on May 17, 2005, and this is the 

current version in the rule book. 

The jurisdiction of the AVAPCD and the AVAQMD were specified in the statutes as 

the portion of the Los Angeles County contained within the MDAB. The MDAB was 

formerly known as the Southeast Desert Air Basin (SEDAB). In 1997 the SEDAB was 

split into the MDAB and the Salton Sea Air Basin. Descriptions of these air basins can 

be found in 17 Cal. Code Regs. §§60109 and 60144. Since USEPA adopts SIP 

revisions in California as effective within jurisdictional boundaries of local air districts, 

when the local air district boundaries change the SIP as approved by USEPA for that 

area up to the date of the change remains as the SIP in that particular area. Thus, upon 

creation of the AVAPCD on July 1, 1997 the AVAPCD acquired the SIP applicable to 

the Antelope Valley portion of the SCAQMD that was effective as of June 30, 1997. 

Likewise the AVAQMD acquired the SIP that was effective in the jurisdiction of the 

AVAPCD as of December 31, 2000. Therefore, the SIP history for this region is based 

upon the rules adopted, effective, and approved for the Antelope Valley by SCAQMD. 

The last amendment prior to the creation of the AVAPCD was the August 7, 1981 

version of SCAQMD Rule 218. This version was submitted by the California Air 

Resources Board (CARB) on October 23, 1981 for inclusion in the State 

Implementation Plan (SIP) and was approved into the SIP on July 6, 1982 (47 FR 

29231). 

The AVAQMD subsequently amended Rule 218 on May 17, 2005, and submitted the 

rule to CARB on December 7, 2005. This rule amendment was approved into the SIP 

at73 FR 51226 on September 2, 2008. Therefore, the May 17, 2005 version is the 

current version in the SIP. 

2. SIP Analysis. 

Rule 218 has been amended to address the USEPA request that the technical and 

quality assurance requirements of these rules be updated in conjunction with the 

amendment of Rule 431.1 – Sulfur Content in Gaseous Fuels. The AVAQMD 

will request that CARB submit Rule 218 – Continuing Emission Monitoring to 

replace the existing October 23, 1981 version, in the SIP. 

The AVAQMD will request that CARB submit Rule 218.1 – Continuous Emission 

Monitoring Performance Specifications as a new rule for inclusion in the State 

Implementation Plan. 
18 AVAQMD Rule 218 and 218.1 

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AVAQMD Rule 218 and 218.1 A-1

Continuous Emission Monitoring 

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APPENDIX "A"

Rule 218 – Continuous Emission Monitoring and 

Rule 218.1 – Continuous Emission Monitoring Performance Specifications 

Iterated Version 

The iterated version is provided so that the changes to an existing rule may be easily found. The manner 

of differentiating text is as follows: 

1. Shaded text identifies new or revised language. 

2. Lined out text identifies language which is being deleted. 

3. Normal text identifies the current language of the current rule which will remain unchanged by the 

adoption of the proposed amendments. 

4. Italicized text identifies explanatory material that is not part of the proposed language. 
A-2 AVAQMD Rule 218 and 218.1 

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(Adopted: 1/ 9/76; Amended: 4/1/77; Amended: 8/5/77; Amended:

4/6/79; Amended: 8/7/81; Readopted by Statute: 07/01/97; 

Readopted by Statute: 01/01/02; Amended: 5/17/05; Amended:

mm/dd/yy) 

AVAQMD RULE 218 218-1

Stack Monitoring 

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RULE 218 

Stack Continuous Emission Monitoring 

(A) General 

(1) Purpose 

(a) The purpose of this rule is to specify Continuous Emission Monitoring 

System (CEMS) approvals and standards. 

(2) Applicability 

(a) The provisions of this rule shall apply to all sources that require CEMS as 

specified in the regulations or permit conditions, with the following 

exceptions: [Derived from SCAQMD Rule 218 §(b)(1).] 

(i) This rule shall not apply to CEMS subject to Regulation IX – 

Standards of Performance for New Stationary Sources, Regulation 

X – National Emissions Standards for Hazardous Air Pollutants, 

or Rule 3010 – Acid Rain Provisions of Federal Operating 

Permits. 

(ii) This rule shall not apply to CEMS subject to permit conditions 

where the purpose of the CEMS is to monitor the performance of 

the basic and/or control equipment and not to determine 

compliance with any applicable limit or standard. 

(iii) This rule shall not apply to CEMS where alternative performance 

specifications are required by another District rule. 

(B) Definitions 

[Relocated from former section (G). New definitions are from SCAQMD 

Rule 218 unless otherwise indicated.]

(1) “Analyzer” – The part of the CEMS that analyzes the appropriate gaseous 

constituents of the conditioned gaseous sample or measures stack gas volumetric 

flow and fuel flow rates, as applicable. 
218-2 AVAQMD RULE 218 

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(a) Contaminant Analyzer – The part of the CEMS that detects the air 

contaminant and represents those concentrations in a signal output. 

(b) Diluent Analyzer – The part of the CEMS that detects oxygen, carbon 

dioxide or other Diluent Gas concentrations and represents those 

concentrations in a signal output. 

(c) Fuel Flowmeter – The part of the CEMS that detects the parameters of all 

essential measurement sub-systems (e.g., temperature, pressure, 

differential pressure, frequency, gas density, gas composition, heating 

value) and generates signal outputs which are a function of the fuel flow 

rate and all essential measurement subsystem parameters. 

(d) Stack Flowmeter – The part of the CEMS that detects the parameters from 

all essential measurement sub-systems (e.g., temperature, static and 

atmospheric pressure, gas density, gas composition, molecular weight, gas 

moisture content) and generates signal outputs which are a function of the 

stack gas volumetric flow rate and all essential measurement sub-system 

parameters. 

(2) “Calibration” – A procedure performed to ensure that the CEMS accurately 

measures and records air contaminant or Diluent Gas concentration, flow rate and 

other parameters necessary to generate data, as evidenced by Calibration Checks, 

and achieved by periodic manual or automatic adjustment.An operating condition 

of the monitoring system whereby the system is accurately recording the 

concentration of the specific air contaminant or diluent gas as evidenced by 

calibration checks, achieved by periodic manual or automatic adjustment. 

[Modified for consistency with SCAQMD Rule 218 definition.]

(3) “Calibration Check” – A procedure performed to determine the CEMS response of 

the systemto a given gaseous compound concentrationby means of injecting a 

certified calibration gas mixture into the system, or the insertion of a span cell into 

the internal light path of the analyzer. A certified calibration gas mixture is 

injected into the CEMS as close to the probe tip as practical. 

(3) Calibration Drift** - The change in the monitoring system output over a stated 

time period of normal continuous operation when the air contaminant or diluent 

gas concentration at the time of the measurements is the same known upscale 

value, or simulated to be the same upscale value by use of a span cell. 

(4) Calibration Error** - The difference between the air contaminant or diluent gas 

concentration indicated by the monitoring system and the known concentration of 

the span gas or the equivalent rating of the span cell. 

(4) “Certified CEMS” – A CEMS installed, tested, operated, maintained, and 

calibrated according to the applicable requirements of Rule 218, and that has met 
AVAQMD RULE 218 218-3

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D3: 06/06/12 

the applicable performance specifications according to Rule 218 (D)(1)(b), and, 

has received written approval and conditions thereto applying, from the APCO. 

(5) Calibration Gas - A mixture of the air contaminant gas, or carbon dioxide or 

oxygen in a diluent gas, which, when periodically introduced into the monitoring 

system, is used to check that system's accuracy. 

(5) “Certified Gas Mixture” – A gas mixture manufactured, analyzed and certified

according to “EPA Traceability Protocol for Assay and Certification of Gaseous 

Calibration Standards” – EPA-600/R97/121, September 1997 Revision (EPA 

Protocol) or any subsequent version published by EPA. This definition 

incorporates by reference EPA Protocol. A mixture analyzed, by replicate 

samples, by the manufacturer by referring to National Bureau of Standards 

Reference Materials, such that a statement of the precision of the analysis can be 

made. [Modified for consistency with SCAQMD rule definition.] 

(6) “Continuous Emissions Monitoring System” (CEMS) – The total combined 

equipment and systems required to continuously determine air contaminants and 

Diluent Gas concentrations and/or mass emission rate of a source effluent (as 

applicable). The CEMS consists of three major subsystems: Sampling Interface, 

Analyzer, and Data Acquisition System. 

(7) “Continuous Monitoring” – Monitoring in which a minimum of one (1) 

measurement (e.g., concentration, mass emission, flow rate) is taken and recorded 

each minute. 

(8) “Data Acquisition System” (DAS) – The part of the CEMS that processes data 

generated by the Analyzer and records the results, thus creating a permanent 

record of the output signal in terms of concentration, flow rate, and/or any other 

applicable parameter necessary to generate the required data in units of applicable 

standard. The DAS consists of all equipment, such as a computer, required to 

convert the original recorded values to any values required for reporting. 

(9) “Diluent Gas” – A gas present in a calibration gas mixture or in the source 

emissions from a source which is present in quantities significantly larger than the 

air contaminant. 

(10) “Laboratory Approval Program” (LAP) – A program administered by the South 

Coast Air Quality Management District (SCAQMD) that grants test-methodspecific approvals to independent testing laboratories or firms that perform tests to 

determine source compliance with SCAQMD rules and regulations. 

(11) “Modification Requiring Recertification” – Any change to the basic equipment, 

control equipment, contaminant concentration, interfering substances, or CEMS 

(or SCEMS) that is deemed by the APCO to have a potential for adversely 

affecting the ability of the CEMS to provide accurate, precise and timely data 
218-4 AVAQMD RULE 218 

Stack Monitoring 

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representative of the stack emissions for which the CEMS (or SCEMS) is 

required. 

(8) Ninety-Five Percent Confidence Interval - The statistically determined range 

within which there is a ninety-five percent (95%) probability all values determined 

will lie. 

(9) Operational Period - A minimum period of time during which the monitoring 

system shall operate, according to the performance and equipment specifications, 

without unscheduled maintenance, repair, or adjustment. 

(10) Parts Per Million - A volume concentration measurement, indicating the 

volumetric quantity of the gas in question, dispersed in one million volumes of gas 

mixture, reported on a dry basis. 

(12) “Quality Assurance/Quality Control (QA/QC) Plan” – A written document in 

which the specific procedures for the operation, Calibration, and maintenance of a 

Certified CEMS are described in detail, including additional quality assurance 

assessments and the corrective action system. The purpose of this plan is to 

ensure that the CEMS generates, collects, and reports valid data that is precise, 

accurate, complete, and of a quality that meets the requirements, performance 

specifications, and standards of Rules 218 and 218.1. 

(11) Reference Method - The official test method employed by the District to 

determine compliance with the rules. 

(12) Relative Accuracy - The degree of correctness with which the monitoring system 

yields the value of gas concentration of a sample relative to the value given by the 

reference method or to the allowed concentration. This accuracy is expressed in 

terms of error, which is the absolute value of the mean of the differences between 

the pared concentration measurements plus the absolute value of the ninety-five 

percent (95%) confidence interval. It is expressed as a percentage of the mean 

reference method value or of the allowed concentration. When a rule requires a 

correction of the air contaminant concentration to a specific O2 or CO2

concentration, the relative accuracy requirement shall apply to the corrected 

concentration value. 

(13) Response Time - The time interval from a step change in the air contaminant or 

gas diluent concentration at the input to the monitoring system to the time at 

which ninety-five percent (95%) of the corresponding final value is reached as 

displayed on the monitoring system data recorder. 

(13) “Routine Maintenance” – Preventive evaluation and repair (if necessary) of CEMS 

performed at specified intervals to preclude System Failure. Routine Maintenance 

may be performed as recommended by the manufacturer or a documented standard 

operating procedure determined through operating experience and approved by the 
AVAQMD RULE 218 218-5

Stack Monitoring 

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Executive OfficerAPCO. Repairs to a malfunctioning system are excluded from 

this definition.An operation, recommended by the manufacturer, to be performed 

at specified intervals, to preclude system failure. Repairs to a malfunctioning 

system are excluded from this definition. 

(15) Span Cell - A sealed cell of fixed length, containing a known concentration of an 

air contaminant, which is inserted into the internal light path of the analyzer to 

provide a measurement output that corresponds to a known concentration of that 

air contaminant. 

(16) Stack Monitoring System, or Monitoring System - The total equipment required 

for the determination of concentrations of air contaminants and diluent gases in a 

source effluent. The system consists of three major subsystems: 

(14) “Sampling Interface” –That part of the CEMS that performs one or more of the 

following operations: delineation, acquisition, transportation, and conditioning of 

a sample of the source effluent or protection of the analyzer from the hostile 

aspects of the sample or source environment. sample acquisition using one or 

more of the following operations: extraction, physical/chemical separation, 

transportation or conditioning of a representative sample from a designated 

source. 

(b) Analyzer 

(i) Air Contaminant Analyzer - that portion of the monitoring system 

that senses the air contaminant and generates a signal output that is 

a function of the concentration of that gas. 

(ii) Diluent Analyzer - that portion of the monitoring system that 

senses the concentration of oxygen or carbon dioxide and generates 

a signal output that is a function of the concentration of that gas. 

This subsystem is required only for sources noted in a (a)(1)(A). 

(c) Data Recorder - that portion of the monitoring system that provides a 

permanent record of the output signal in terms of concentration units, 

including additional equipment such as computers required to convert the 

original recorded value to any value required for reporting. [See (B)(1) and 

(B)(8).] 

(15) “Semi-Continuous Emission Monitoring” – A monitoring technique in which a 

minimum of one (1) measurement (e.g., concentration, mass emission, flow rate) 

is taken and recorded every fifteen (15) minutes. 

(16) “Semi-Continuous Emission Monitoring System” (SCEMS) – The total combined 

equipment and systems to semi-continuously determine air contaminant and 

Diluent Gas concentrations and/or the mass emission rate in a source effluent (as 

applicable). The system consists of three (3) major subsystems: Sampling 
218-6 AVAQMD RULE 218 

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Interface, Analyzer and DASata cquisition ystem. This class of monitoring 

includes, but is not limited to, gas chromatography, integrated sensitized tape 

analyzer, other sample integration based technologies, and Time-Shared CEMS. 

(17) “South Coast Air Quality Management District” (SCAQMD) – The air quality 

district created pursuant to Division 26, Part 3, Chapter 5.5 of the California 

Health & Safety Code (commencing with §40400). [Derived from AVAQMD Rule 

1124.] 

(18) “System Failure” – Inability of the CEMS to meet the requirements of Rule 218.1 

– Continuing Emission Monitoring Performance Specifications, or, Code of 

Federal Regulations, Title 40 – “Protection of Environment,” Part 60 – “Standards 

of Performance for New Stationary Sources,” Appendix F – Quality Assurance 

Procedures.”occurs anytime the monitoring system is suspected or known to be 

unable to meet the requirements of (c)(2) or (b)(2), as applicable. 

(19) “Time- Sharing” – A monitoring technique where an Analyzer, and possibly the 

associated sampling conditioning system, is used on more than one source. 

(18) Use Factor - The amount of time used per year divided by the amount of time 

available for use per year, expressed as a percent.

(20) “Working Day” – Monday through Friday, excluding holidays. 

(21) “Zero Check” – A procedure performed to determine the response of the CEMS to 

a given Zero Gas standard by means of injecting the Zero Gas into the CEMS as 

close to the probe tip as practical. 

 (19) Zero Calibration Reflector - A device which is inserted into the internal light path 

of the analyzer to provide a measurement output that simulates a zero gas 

concentration. 

(20) Zero Drift** - The change in the monitoring system over a stated period of time of 

normal continuous operation when the air contaminant or diluent gas 

concentration at the time of the measurements is zero, or is simulated to be zero 

by use of a zero calibration reflector. 

(22) “Zero Gas” – A gas containing less than a specified amount of the air contaminant 

or Diluent Gas which, when periodically injected into the CEMSmonitoring 

system, is used to check CEMS that system's response to the absence of the air 

contaminant or Diluent Gas. 

 *The operational period test performed prior to final approval shall be preceded by 

a one hundred sixty eight (168) hour (minimum) conditioning period during which 

the system shall be operated without unscheduled maintenance, repair, or 

adjustment. 
AVAQMD RULE 218 218-7

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 **Expressed as the sum of the mean value plus the ninety-five percent (95%) 

confidence interval of a series of tests. 

(AC) Stack Monitoring Requirements for New, Modified and Existing CEMS

(1) The owner or operator of any equipment described belowsubject to this rule shall 

provide,; properly install, operate and maintain in calibrationCalibration and, in

good working order and in operation; approved stack monitoring systemsa 

Certified CEMS to measure the concentration and/or emission rates, as applicable, 

of the following air contaminants and diluent Diluent gasesGases, flow rates, and 

other required parameters in the emissions from the sources indicated. The owner 

or operator shall also provide the necessary records and any other data necessary 

for to calculateing air contaminant emission rates or concentrations, as specified in 

Rule 218 Sections (F) and (G). 

 (a) Oxides of nitrogen (NOx), and carbon dioxide (CO2) or oxygen (02), from 

steam generators with a heat input of 63 million kilogram calories (250 

million British Thermal Units) or more per hour and with a use factor of at 

least thirty percent (30%). 

(b) Sulfur dioxide (SO2) from steam generators with a heat input of 63 million 

kilogram calories (250 million British Thermal Units) or more per hour 

and with a use factor of at least thirty percent (30%) if control equipment is 

used. 

(c) Oxides of nitrogen (NOx) from all nitric acid production plants. 

(d) Gaseous sulfur compounds calculated as sulfur dioxide (SO2) from all 

sulfuric acid production plants, carbon monoxide boilers or furnaces of the 

regenerators of fluid catalytic cracking units, and all fluid cokers. 

(e) Sulfur dioxide (SO2) from sulfur recovery plants with oxidizing tail gas 

units, and with reducing tail gas units using continuous incineration for 

control of hydrogen sulfide (H2S). 

(2) The Air Pollution Control Officer (APCO) may require a person to provide, 

properly install, maintain in calibration, in good working order and in operation, 

an approved stack monitoring system to measure air contaminants in emission 

gases when that person installs, operates, or uses any equipment which emits 

900,000 kilograms (992 tons) or more per year of carbon monoxide (CO) or 

90,000 kilograms (99 tons) or more per year of any air contaminant except carbon 

monoxide (CO). The APCO shall report to the District Board in writing when he 

requires the installation of a stack monitoring system under the provisions of this 

subpart.
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(BD) Requirements for New and Modified CEMS and SCEMS 

(1) Application and Approval Requirements of for New and Modified CEMS 

Monitoring Systems

(1a) The owner or operator of any equipment subject to this Rule shall submit 

to the APCO an “Application for CEMS” or “Application for CEMS 

Modification”, as applicable. Any application submitted on or after [date 

of amendment], shall require an initial approval by the APCO prior to 

installation of a new CEMS or modification of an existing CEMS. The 

APCO shall notify the applicant in writing within 60 calendar days of 

receipt of an application for a new CEMS, or within 30 calendar days of 

receipt of an application for a modification to an existing CEMS, if the 

application contains sufficient information to be deemed complete. Where 

an application has been determined to be incomplete, the APCO shall 

request specific information needed to complete the application. Upon 

receipt of any complete resubmittal or the additional information, plans or 

specifications after the application has been deemed incomplete, a new 30-

day period shall begin during which the APCO shall determine the 

completeness of the application and notify the applicant. Within 90 days 

of installation, a person operating or using CEMS shall undertake a series 

of certification tests. If the equipment served by the CEMS is not 

operating at the time of complete CEMS installation, then the CEMS shall 

undergo a series of certification tests within 90 days from the next start-up 

of the equipment served by the CEMS. The purpose of the certification 

tests is to demonstrate the CEMS performance pursuant to the 

specifications in accordance with the provisions of Rule 218, Section 

(D)(1)(b). The owner or operator shall notify the APCO in writing at least 

14 days before the scheduled certification test dates. The certification tests 

shall be performed by a testing laboratory approved under the SCAQMD 

LAP. Data from such tests shall be submitted to the APCO within 45 days 

following test completion. If satisfactory performance is demonstrated, 

final approval of the CEMS shall be granted. Subsequent operation and 

maintenance of the Certified CEMS shall be in accordance with the 

provisions of Rule 218, Section (D)(1)(b). After final approval, 

modifications made to the CEMS shall be reviewed and approved by the 

APCO according to the specifications stipulated in Rule 218, Section 

(D)(1)(b), and may require all or a portion of performance tests to be 

conducted. 

(b) Upon submission of an “Application for CEMS” or “Application for 

CEMS Modification” as prescribed in Rule 218 Section (D)(1)(a), the 

applicant shall indicate either one of the following conditions: 
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(i) That the CEMS shall be reviewed and certified according to the 

provisions of Rule 218.1 - , “Continuous Emission Monitoring 

Performance Specifications”, Section (C), and the subsequent 

operation and maintenance of the Certified CEMS shall be in 

accordance with the provisions of Rule 218, Sections (C), (F), (G) 

and (H) and of the requirements of Rule 218.1 Sections (C) and 

(E); or, 

(ii) That the CEMS shall be reviewed and certified according to the 

applicable provisions of the Code of Federal Regulations, Title 40 

– “Protection of Environment”, Part 60 – “Standards of 

Performance for New Stationary Sources” (40 CFR 60), Appendix 

B – “Performance Specifications” (Appendix B), and the 

subsequent operation and maintenance of the Certified CEMS shall 

be in accordance with the provisions of Rule 218, Sections (C), (F), 

(G) and (H), and the requirements of 40 CFR 60, Appendix F – 

“Quality Assurance Procedures” (Appendix F). Notwithstanding 

the requirements of this Section (c)(1)(B)(ii), any alternative test 

methods for 40 CFR 60, Appendices B and F shall be those that are 

listed in Rule 218.1, Table 1 - Reference Methods. 

(c) A “Notification of Pre-Approved Modification” and report of results of 

prescribed quality assurance checks may be submitted in lieu of the 

“Application for CEMS Modification” when the modification has been 

made in accordance with the written technical guidance document 

approved by the APCO. 

(2) Application and Approval Requirements for New and Modified SCEMS 

(a) In- lieu of submitting an application for CEMS per Rule 218, Section 

(D)(1), the owner or operator of any equipment subject to this Rule, may 

elect to submit an application for a SCEMS if the averaging time for the 

applicable limits(s) for which the CEMS is required is 24 hours or greater; 

or, if the owner or operator demonstrates, to the satisfaction of the APCO, 

that no CEMS technology is commercially available for the applicable 

contaminant and the applicable limits. 

(b) If the conditions in Rule 218, Section (D)(2)(a), above, do not apply, the 

owner or operator of any equipment subject to this Rule may still elect to 

submit an application for a SCEMS in lieu of a CEMS, subject to the 

following: 

(i) The owner or operator demonstrates that the concentrations and/or 

emissions required to be monitored would be equivalent to that 

monitored by a CEMS for the applicable averaging period, to the 

satisfaction of the APCO; 
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(ii) The SCEMS shall be capable to take and record a minimum of one

(1) measurement (concentration, mass emission rate and/or flow 

rate, as applicable) every 15 minutes allowing as equally spaced 

data points as practical; 

(iii) The owner or operator shall include in the QA/QC plan the method 

of calculating the 15-minute averages for compliance determination 

to the applicable limit or standard; 

(iv) If an exceedance of the allowable limit or standard is calculated 

using fewer than 100 percent% valid data points, then the District 

shall use any relevant data for the operation of the equipment (basic 

and control, as applicable) to verify the calculated exceedance; and 

(v) If a Time -Shared SCEMS is proposed, it shall meet the 

performance specifications of Rule 218.1, Section (F). 

(c) The requirements for the application submittal and approval of CEMS as 

provided in Rule 218, Section (D)(1) shall also apply for SCEMS 

applications. 

(3) Operation of CEMS or SCEMS During Certification Testing 

CEMS or SCEMS shall be certified as configured for the normal operation of the 

CEMS or SCEMS with respect to sample acquisition, sample conditioning, 

pollutant/diluent detection, data requirements and reporting. 

(4) QA/QC Plan for New or Modified CEMS or SCEMS 

(a) The owner or operator of CEMS or SCEMS who elects the performance 

specifications according to Rule 218, Section (D)(1)(b)(i), shall submit to 

the APCO for approval a CEMS QA/QC Plan within 45 days of CEMS 

installation and no later than 30 days before the certification tests. 

(b) Alternative Quality Assurance Practices 

The owner or operator of CEMS or SCEMS who elects the performance 

specifications according to Rule 218, Section (D)(1)(b)(i), may choose to 

develop alternative CEMS operational test requirements to be included in 

the CEMS QA/QC procedures that assure data of equivalent or better 

quality. These alternative QA/QC procedures shall be submitted with the 

facility QA/QC Plan and are subject to the approval of the APCO. 

(E) Requirements for Existing CEMS and SCEMS 

(1) Requirements for Existing CEMS 

(a) A CEMS installed and granted final approval before May 14, 1999[date of 

rule amendment] shall be maintained and operated according to the 
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provisions of Rule 218, Sections (C), (F), (G) and (H), and the 

requirements of Rule 218.1, Sections (D) and (E). 

(b) A CEMS application for initial and final approval submitted to the APCO 

before May 14, 1999[date of rule amendment] shall be reviewed and 

approved by the APCO according to the specifications and requirements of 

Rule 218.1, Sections (D) and (E). After final approval, the CEMS shall be 

operated and maintained according to the provisions of Rule 218, Sections 

(C), (F), (G) and (H), and the requirements of Rule 218.1, Sections (D) and 

(E). 

(c) Modifications Requiring Recertification to any existing CEMS shall be 

reviewed and approved according to the conditions under Rule 218 Section 

(D)(1)(b)(i) or (ii), as applicable. After final approval, the modified 

CEMS shall be operated and maintained according to the conditions under 

Rule 218, Section (D)(1)(b)(i) or (ii), as applicable. 

(di) All existing CEMS as prescribed in Rule 218, Sections (E)(1)(a) and (b) 

shall comply with the provisions of Rule 218.1, Sections (C) and (DE), or 

40 CFR 60 Appendices B and F, as applicable, and of Rule 218, Sections 

(C) and (D), no later than May 14, 2006[seven (7) years from date of rule 

amendment]. [Typographical error corrected pursuant to EPA comment of 

04/25/12. There is only one facility in the District with an existing CEMS 

currently subject to the provisions of this rule. This facility has indicated 

that they are compliant with the provisions of the rule and the additional 

time provision is not necessary. Removed in response to EPA comment 

1b of 04/25/12.] 

(iie) The requirements of Rule 218, Section (E)(1)(d)(i) shall be waived for a 

period of three (3) years if the owner or operator demonstrates, to the 

satisfaction of the Executive OfficerAPCO, that the existing CEMS is 

providing data that areis of a quality commensurate with the original 

performance specifications and other indicators of consistent data quality. 

Data quality factors that will be considered include: 

(i) Relative Accuracy; 

(ii) Calibration Error; 

(iii) Calibration Drift; 

(iv) Zero Drift; 

(v) Valid data return percentage; 

(vi) Availability or up-time percentage; 

(vii) Breakdown frequency and duration; and 

(viii) Excursions beyond quality control limits in QA/QC plan. 
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The owner or operator may apply for a waiver under this subsection every three (3) years after May 14, 2006[Seven (7) years 

from date of rule amendment]. This subsection shall not apply to 

existing CEMS that are required to comply with the provisions of 

Rule 218.1, Sections (C) and (E), or, 40 CFR 60, Appendices B 

and F, as applicable, and Rule 218, Sections (C) and (D), as a result 

of CEMS Modifications Requiring Recertification, rule 

implementation, or, compliance with a permit condition.[There is 

only one facility in the District with an existing CEMS currently 

subject to the provisions of this rule. This facility has indicated 

that they are compliant with the provisions of the rule and the 

additional time provision is not necessary. Removed in response to 

EPA comment 1b of 04/25/12.] 

(efd) The owner or operator of existing CEMS shall develop and implement a 

written Quality Assurance/ Quality Control (QA/QC) Plan no later than 

May 14, 2000[one (1) year from date of rule amendment]. The written 

QA/QC Plan shall be kept on record and available for inspection upon 

request by the APCO. 

(fg) On or before May 14, 2005[Six (6) years from date of rule amendment], 

the owner or operator of any existing CEMS shall submit to the APCO for 

approval: 

(i) A certification signed by an authorized representative of the facility 

that the existing CEMS meets the requirements of Rule 218, 

Section (D); 

(ii) An “Application for CEMS Modification”, with the applicable 

fee(s) as specified in Rule 301; or 

(iii) An application for waiver according to Rule 218, Section (E)(1)(d), 

with documentation supporting the required demonstration. [There 

is only one facility in the District with an existing CEMS currently 

subject to the provisions of this rule. This facility has indicated 

that they are compliant with the provisions of the rule and the 

additional time provision is not necessary. Removed in response to 

EPA comment 1b of 04/25/12.]

(2) Requirements for Existing SCEMS 

(a) A SCEMS installed and granted final approval before May 14, 1999 [Date 

of rule amendment] shall be maintained and operated according to the 

provisions of Rule 218, Sections (C), (F), (G) and (H), and the 

requirements of Rule 218.1, Sections (D) and (E). 

(b) A SCEMS application for initial and final approval submitted to the APCO 

before May 14, 1999 [Date of rule amendment] shall be reviewed and 
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approved by the APCO according to the specifications and requirements of 

Rule 218.1, Sections (D) and (E). After final approval, the SCEMS shall 

be operated and maintained according to the provisions of Rule 218, 

Sections (C), (F), (G) and (H), and the requirements of Rule 218.1, 

Sections (D) and (E). 

(c) Modifications Requiring Recertification to any existing SCEMS shall be 

reviewed and approved according to the conditions under Rule 218 Section 

(D)(1)(b)(i) or (ii), as applicable. After final approval, the modified 

CEMS shall be operated and maintained according to the conditions under 

Rule 218, Section (D)(1)(b)(i) or (ii), as applicable. 

(d) The owner or operator of an existing SCEMS operating on or before May 

14, 1999 [Date of rule amendment] shall be required to comply with the 

provisions of Rule 218.1 Section (F) - “Time -Sharing Requirements” and 

with the provisions of Rule 218.1 Sections (C) and (E), or, 40 CFR 60 

Appendix B and F, as applicable, when the equipment served by the TimeShared SCEMS is modified such that: 

(i) One or more of the sources monitored requires a new monitoring 

range; 

(ii) The operating permit is modified to require Continuous 

Monitoring; or, 

(iii) An applicable source specific rule is adopted or revised to require 

Continuous Monitoring. 

Subsequent operation and maintenance of the SCEMS shall be 

according to the provisions of Rule 218, Section (D)(1)(b)(i) or (ii), 

as applicable. 

(F) Retention of Records for New, Modified and Existing CEMS and SCEMS 

(1) The records of the data obtained from the CEMS recording devices shall clearly 

indicate concentrations or emission rates, or both, as specified by the APCO. 

Records shall be maintained by the CEMS owner or operator for a minimum 

period of five (5) years, unless otherwise specifically provided by another District 

regulation or permit conditions, and, shall be made available to the APCO upon 

request. 

(2) All calculations, raw parameter data used for calculations, records of the 

occurrence and duration of any start up, shutdown or malfunction, performance 

test, evaluation, Calibration, adjustment and maintenance of the CEMS as well as 

calibration gas traceability shall be retained by the CEMS operator for a minimum 

period of five (5) years unless otherwise specifically provided by another District 
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regulation or permit conditions, and shall be made available to the APCO upon 

request. 

(G) Reporting Requirements for New, Modified and Existing CEMS and 

SCEMS 

Unless otherwise specifically provided by another District regulation or permit 

conditions, the following reporting requirements shall apply to new, modified and 

existing CEMS and SCEMS: 

(1) A CEMS owner or operator shall provide a summary of the concentration and/or 

emission rate data, as applicable, obtained from the CEMS, as well as any 

additional information specified by the APCO, to evaluate the accuracy and 

precision of the measurements. The summary shall be submitted once every six 

(6) months to the APCO, except when more frequent reporting is specifically 

required by another District rule, or the APCO, on a case-by-case basis, 

determines that more frequent reporting is necessary to accurately assess the 

compliance status of the source. The summary report shall be submitted within 30 

days following the end of the six (6)-month period being reported, in the form and 

manner prescribed by the APCO. The summary shall be maintained on-site in a 

retrievable and readable form and shall be made available to the APCO upon 

request. The submitted summaries shall be available for public inspection at the 

District. 

(2) The CEMS owner or operator shall report any concentration level and/or emission 

rate, as applicable, in excess of the regulated limit within 24 hours or the next 

Working Day after such occurrence in the form and manner prescribed by the 

APCO. The report shall include the following information: 

(a) Time intervals, date, and magnitude of the excess concentration level, 

nature and cause of the excess concentration (if known), corrective 

action(s) taken, preventive measure(s) adopted, specific location of CEMS, 

the equipment or CEMS involved and the facility contact person. 

(b) The averaging period used for data reporting shall correspond to the 

averaging period specified in the rule or permit condition governing the 

concentration and/or emission rate, if applicable. 

(3) Reports of CEMS Failure or Shutdown 

(a) The CEMS owner or operator shall notify the APCO within 24 hours or 

the next Working Day, in the event of a system failure or shutdown, which 

exceeds 24 hours. Zero and Calibration Checks and Routine Maintenance 

do not require reporting. 
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(b) In the case of a CEMS failure or shutdown, compliance with the provisions 

of Rule 218, Section (C) is waived for a period not to exceed 96 

consecutive hours. Such waiver is extended beyond 96 consecutive hours 

only if a petition for an interim variance is filed in accordance with 

Regulation V – Procedures Before the Hearing Board and shall terminate 

at the time the Hearing Board acts upon such variance petition. CEMS 

owners or operators of qualified facilities may obtain a Hearing Board 

approval of an alternative operating condition following the established 

procedure in District Rule 518.2 - Federal Alternative Operating 

Conditions. 

(c) Regularly scheduled CEMS maintenance shall be deferred until the report 

required under Rule 218, Section (G)(2) is made, if the system is 

measuring a concentration equal to or exceeding the emission standard, 

and if such deferral is not reasonably expected to result in damage to the 

system. 

(d) Continuous emission monitoring requirements shall not apply during 

regular Calibration Checks of the system, or Routine Maintenance and 

repair lasting 60 minutes or less. 

All monitoring systems to be installed after April 6, 1979, require an initial 

approval by theAPCO, prior to installation. The APCO shall act upon an 

application for initial approval within 30 days after filing or within thirty 

(30) days after the applicant furnishes further information, plans and 

specifications requested to complete an application. Upon completion of 

installation, a person operating or using a stack monitoring system shall 

undertake a series of tests to demonstrate the acceptability of the system's 

performance pursuant to (C) below. Within six (6) months of initial 

operation, data from such tests shall be submitted to the APCO for 

approval. If satisfactory performance is demonstrated, a final approval of 

the system shall be granted.

(2) A person operating a monitoring system installed on or before April 6, 

1979, shall, by June 1, 1979, submit a plan to the APCO outlining steps to 

achieve compliance with the performance specifications of (C) below as 

expeditiously as practicable, but in no event later than March 2, 1981. 

Each plan shall include, but shall not necessarily be limited to, dates and 

methods for achieving the following increments of progress: 

1. Submit test results. 

2. Negotiate and sign contracts. 

3. Commence modification or replacement of non-complying 

systems. 
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4. Complete modification or replacement of non-complying systems. 

5. Submit final test results. 

6. Achieve final compliance with (C) below on or before 

March 2, 1981. 

Non-complying systems shall be operated at the level of performance 

indicated by test results. Each system shall be operated in accordance with 

the plan.

(3H) Posting of Written Approval for New, Modified and Existing CMS and 

SCEMS 

A person operating an approved monitoring systemThe CEMS owner or operator of an 

approved CEMS shall affix such a written notice of approval or a legible facsimile thereof 

upon the equipment or within 26 feet of the equipment as prescribed in District Rule 206,

in a manner such that it is clearly visible, and legible, and safely accessible. In the event 

that the equipment is so constructed or operated that the notice of approval or its legible 

facsimile cannot be so placed, such notice or legible facsimile shall be mounted on a 

location approved by the APCO. 

(C) Monitoring System Standards 

(1) The monitoring system shall be installed at a location such that air contaminant 

and diluent gas concentration measurements can be made which are representative 

of the stack emissions of the affected facility. 

(2) Prior to final approval of the monitoring system, it shall meet, and it shall 

thereafter be operated in accordance with, the following performance and 

equipment specifications:

 (a) Monitors for Gaseous Air Contaminants 
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Parameter Specifications 

(i) Operational Period* Greater than or equal to 168 hours. 

(ii) Calibration Error** Less than or equal to 5 percent. 

(iii) Response Time Less than or equal to 10 minutes. 

(iv) Zero Drift (2-hour)** Less than or equal to 2 percent of full scale 

reading. 

(v) Zero Drift**(24-hour) Less than or equal to 2 percent of full scale 

reading. 

(vi) Calibration Drift (2-hour)** Less than or equal to 2 percent of scale 

reading. 

(vii) Calibration Drift (24-hour)** Less than or equal to 2.5 percent of full scale 

reading. 

(viii) Relative Accuracy** Less than or equal to 20 percent of the mean 

value of the reference method test data or less 

than or equal to 10 percent of the allowed 

concentration, whichever is greater. 

(b) Monitors for Diluent Gases 

Parameter Specifications 

(i) Operational Period* Greater than or equal to 168 hours. 

(ii) Calibration Error** Less than or equal to 5 percent. 

(iii) Response Time Less than or equal to 10 minutes. 

(iv) Zero Drift (2-hour)** Less than or equal to 0.4 percent CO2 or 02. 

(v) Zero Drift (24-hour)** Less than or equal to 0.5 percent CO2 or 02. 

(vi) Calibration Drift (2-hour)** Less than or equal to 0.4 percent CO2 or 02. 

(vii) Calibration Drift (24-hour)** Less than or equal to 0.5 percent CO2 or 02. 

(3) The monitoring system shall be operated according to the following standards: 

(a) Calibration gases shall meet the following criteria: 

(i) For gaseous air contaminant monitors, the mixture shall be certified 

to be within two percent (2%) of the stated value. 

(ii) For carbon dioxide and oxygen monitors, the mixture shall be 

certified to be within two-tenths percent (0.2%) carbon dioxide or 

oxygen of the stated value. Ambient air may be used for oxygen 

monitors if the span is higher than twenty one percent (21%) 

oxygen. 

(b) Zero gases used shall meet the following criteria: 

(i) For gaseous air contaminant monitors, the gas shall be certified by 

the manufacturer to contain less than 1 part per million of the air 
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contaminant (except carbon monoxide, less than 10 parts per 

million), or alternately, ambient air may be used. 

(ii) For carbon dioxide and oxygen monitors, the gas shall be certified 

by the manufacturer to contain less than 100 parts per million of 

carbon dioxide or oxygen. 

(c) Calibration gases shall be manufactured, analyzed and certified according 

to USEPA Traceability Protocol for Assay and Certification of Gaseous 

Calibration Standards (EPA-600/R97/121) as revised September 1997 or 

any subsequent version as published by USEPA 

(d) Calibration checks shall be performed at least once each day at regular 

intervals. 

(e) The instrument full scale reading shall be equivalent to approximately two 

hundred percent (200%) of the concentration limit specified in the 

applicable rule, or at a value approved by theAPCO. Oxygen and carbon 

dioxide instruments full scale readings shall be such that the full range of 

concentrations encountered can be measured. 

(f) Regular scheduled maintenance of the monitoring system shall be deferred 

until the report required under Section (E)(2) is made, if the system is 

measuring a concentration equal to or exceeding the emission standard, 

and if such deferral will not reasonably be expected to result in damage to 

the system. 

(g) The monitoring system shall complete a minimum of one cycle of 

operation (sampling, analyzing, and data recording), for each successive 

fifteen (15) minute period. 

(h) The requirements of section (C)(3)(g) shall not apply to the following 

conditions: 

(i) Regular calibration checks of the system. 

(ii) Routine maintenance and repair of sixty (60) minutes or less 

duration. 

(4) Following final approval, if significant modifications are made to the system, a 

demonstration of the ability of the system to operate in accordance with the 

specifications of (c)(2) may be required at the discretion of the Executive Officer. 

(5) Span cell calibration techniques may be employed with in situ monitors, not 

extracting the gas sample from the stack if the criteria of (c)(2)(A)(ii), (vi) and 

(vii) can be met and if the use of the cell provides a check of all analyzer internal 

mirrors and lenses and all electronic circuitry including the source and detector 

assembly which are normally used in sampling and analysis. 
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(6) Zero calibration reflector techniques may be employed with in situ monitors, not 

extracting the gas sample from the stack, if the criteria of (c)(2)(A)(iv) and (v) can 

be met. 

(D) Retention of Records 

(1) The records of the data obtained from the recording devices of the stack 

monitoring system shall clearly indicate concentrations as specified by theAPCO. 

Records shall be maintained by the owner or operator of a monitoring system for a 

period of at least two (2) years and shall be made available to the APCO upon 

request. 

(2) All records of the occurrence and duration of any start up, shutdown or 

malfunction, performance test, evaluation, calibration, adjustment and 

maintenance of the monitoring system as well as calibration gas traceability or 

span cell specifications documents, shall be retained by the monitoring system 

operator for a period of at least two (2) years and shall be made available to the 

APCO upon request. 

(E) Reporting 

(1) A person operating a stack monitoring system shall provide a summary of the 

concentration and emission data obtained from such system, as well as any 

additional information specified by the APCO to evaluate the accuracy and 

precision of the measurements. The summary shall be submitted monthly to the 

APCO within thirty (30) days of the end of the month being reported, in the form 

and manner prescribed by him. The summary shall be available for public 

inspection at the office of the Air Quality Management District. 

(2) A person operating a monitoring system shall report any concentration level in 

excess of the regulated limit to the APCO within ninety-six (96) hours after such 

occurrence in the form and manner prescribed by him. The report shall include 

the following information: 

(a) Time intervals, date, and magnitude of the excess concentration level; 

nature and cause of the excess (if known), corrective actions taken and 

preventive measure adopted. 

(b) Averaging period used for data reporting shall correspond to the averaging 

period specified in the rule governing the concentration limit in question. 

(3) Reports of Monitoring System Failure or Shutdown 

(a) A person operating a monitoring system shall notify the Executive Officer 

within ninety-six (96) hours, in a form and manner prescribed by him, in 
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the event of a system failure or shutdown for repair, which exceeds sixty 

(60) consecutive minutes. Zero and calibration checks and routine 

maintenance do not require reporting. 

(b) In the case of a monitoring system failure or shutdown for repair, 

compliance with the provisions of subsection (a) is waived for a period not 

to exceed ninety-six (96) consecutive hours. Such waiver is extended 

beyond ninety-six (96_ consecutive hours only if a petition for an interim 

variance is filed in accordance with Regulation V and shall terminate at the 

time the Hearing Board acts upon such variance petition. 

(F) Exemption 

Any source subject to the provisions of (a)(1) above may obtain an exemption from the 

provisions of (a)(1) above upon demonstration to the satisfaction of the APCO that the 

source is not subject to a District rule or regulation prohibiting or limiting the discharge of 

any air contaminants which are the subject of (a)(1). 

(G) Definitions 

(1) Calibration - An operating condition of the monitoring system whereby the system 

is accurately recording the concentration of the specific air contaminant or diluent 

gas as evidenced by calibration checks, achieved by periodic manual or automatic 

adjustment. 

(2) Calibration Check - A procedure to determine the response of the system to a 

given gaseous compound concentration by means of injecting a certified 

calibration gas mixture into the system, or the insertion of a span cell into the 

internal light path of the analyzer. 

(3) Calibration Drift** - The change in the monitoring system output over a stated 

time period of normal continuous operation when the air contaminant or diluent 

gas concentration at the time of the measurements is the same known upscale 

value, or simulated to be the same upscale value by use of a span cell. 

(4) Calibration Error** - The difference between the air contaminant or diluent gas 

concentration indicated by the monitoring system and the known concentration of 

the span gas or the equivalent rating of the span cell. 

(5) Calibration Gas - A mixture of the air contaminant gas, or carbon dioxide or 

oxygen in a diluent gas, which, when periodically introduced into the monitoring 

system, is used to check that system's accuracy. 
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(6) Certified Gas Mixture - A mixture analyzed, by replicate samples, by the 

manufacturer by referring to National Bureau of Standards Reference Materials, 

such that a statement of the precision of the analysis can be made. 

(7) Diluent Gas - A gas present in a calibration gas mixture or in the emissions from a 

source which is present in quantities significantly larger than the air contaminant. 

(8) Ninety-Five Percent Confidence Interval - The statistically determined range 

within which there is a ninety-five percent (95%) probability all values determined 

will lie. 

(9) Operational Period - A minimum period of time during which the monitoring 

system shall operate, according to the performance and equipment specifications, 

without unscheduled maintenance, repair, or adjustment. 

(10) Parts Per Million - A volume concentration measurement, indicating the 

volumetric quantity of the gas in question, dispersed in one million volumes of gas 

mixture, reported on a dry basis. 

(11) Reference Method - The official test method employed by the District to 

determine compliance with the rules. 

(12) Relative Accuracy - The degree of correctness with which the monitoring system 

yields the value of gas concentration of a sample relative to the value given by the 

reference method or to the allowed concentration. This accuracy is expressed in 

terms of error, which is the absolute value of the mean of the differences between 

the pared concentration measurements plus the absolute value of the ninety-five 

percent (95%) confidence interval. It is expressed as a percentage of the mean 

reference method value or of the allowed concentration. When a rule requires a 

correction of the air contaminant concentration to a specific O2 or CO2

concentration, the relative accuracy requirement shall apply to the corrected 

concentration value. 

(13) Response Time - The time interval from a step change in the air contaminant or 

gas diluent concentration at the input to the monitoring system to the time at 

which ninety-five percent (95%) of the corresponding final value is reached as 

displayed on the monitoring system data recorder. 

(14) Routine Maintenance - An operation, recommended by the manufacturer, to be 

performed at specified intervals, to preclude system failure. Repairs to a 

malfunctioning system are excluded from this definition. 

(15) Span Cell - A sealed cell of fixed length, containing a known concentration of an 

air contaminant, which is inserted into the internal light path of the analyzer to 

provide a measurement output that corresponds to a known concentration of that 

air contaminant. 
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(16) Stack Monitoring System, or Monitoring System - The total equipment required 

for the determination of concentrations of air contaminants and diluent gases in a 

source effluent. The system consists of three major subsystems: 

(a) Sampling Interface - that portion of the monitoring system that performs 

one or more of the following operations: delineation, acquisition, 

transportation, and conditioning of a sample of the source effluent or 

protection of the analyzer from the hostile aspects of the sample or source 

environment. 

(b) Analyzer 

(i) Air Contaminant Analyzer - that portion of the monitoring system 

that senses the air contaminant and generates a signal output that is 

a function of the concentration of that gas. 

(ii) Diluent Analyzer - that portion of the monitoring system that 

senses the concentration of oxygen or carbon dioxide and generates 

a signal output that is a function of the concentration of that gas. 

This subsystem is required only for sources noted in a (a)(1)(A). 

(c) Data Recorder - that portion of the monitoring system that provides a 

permanent record of the output signal in terms of concentration units, 

including additional equipment such as computers required to convert the 

original recorded value to any value required for reporting. 

(17) System Failure - occurs anytime the monitoring system is suspected or known to 

be unable to meet the requirements of (c)(2) or (b)(2), as applicable. 

(18) Use Factor - The amount of time used per year divided by the amount of time 

available for use per year, expressed as a percent.

(19) Zero Calibration Reflector - A device which is inserted into the internal light path 

of the analyzer to provide a measurement output that simulates a zero gas 

concentration. 

(20) Zero Drift** - The change in the monitoring system over a stated period of time of 

normal continuous operation when the air contaminant or diluent gas 

concentration at the time of the measurements is zero, or is simulated to be zero 

by use of a zero calibration reflector. 

(21) Zero Gas - Agas containing less than a specified amount of the air contaminant or 

diluent gas which, when periodically injected into the monitoring system, is used 

to check that system's response to the absence of the air contaminant or diluent 

gas. 
AVAQMD RULE 218 218-23

Stack Monitoring 

D3: 06/06/12 

 *The operational period test performed prior to final approval shall be preceded by 

a one hundred sixty eight (168) hour (minimum) conditioning period during which 

the system shall be operated without unscheduled maintenance, repair, or 

adjustment. 

 **Expressed as the sum of the mean value plus the ninety-five percent (95%) 

confidence interval of a series of tests. 

[SIP: Approved 7/6/82, 47 FR 29231, 40 CFR 52.220(c)(103)(xviii)(A); Approved 9/28/81, 

46 FR 47451, 40 CFR 52.220(c)(65)(ii); Approved ________, _________, 40 CFR 

52.220(c)(42)(xiv)(A); Approved 9/8/78, 43 FR 40011, 40 CFR 52.220(c)(39)(iii)(C)]

See SIP Table at http://www.avaqmd.ca.gov/Modules/ShowDocument.aspx?documentid=921
218-24 AVAQMD RULE 218 

Stack Monitoring 

D3: 06/06/12 

This Page Intentionally Left Blank 
(Adopted: mm/dd/yy) 

AVAQMD RULE 218.1 218.1-1

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

RULE 218.1 

Continuous Emission Monitoring Performance 

Specifications2

(A) General 

(1) Purpose 

(a) The purpose of this rule is to specify standards, specifications and 

requirements for new, modified and existing Continuous Emission 

Monitoring Systems (CEMS). 

(2) Applicability 

(a) The provisions of this rule shall apply to all sources that require 

CEMS pursuant to District Rule 218 – Continuous Emission 

Monitoring. 

(B) Definitions 

(1) “Analyzer” - The part of the CEMS that analyzes the appropriate gaseous 

constituents of the conditioned gaseous sample or measures stack gas 

volumetric flow and fuel flow rates, as applicable.

(a) Contaminant Analyzer - The part of the CEMS that detects the air 

contaminant concentrations and represents those concentrations in 

a signal output. 

(b) Diluent Analyzer - The part of the CEMS that detects oxygen (O2), 

carbon dioxide (CO2) or other Diluent Gas concentrations and 

represents those concentrations in a signal output.

(c) Fuel Flowmeter - The part of the CEMS that detects the parameters 

of all essential measurement sub-systems (e.g., temperature, 

pressure, differential pressure, frequency, gas density, gas 

composition, heating value) and generates signal outputs which are 

a function of the fuel flow rate and all essential measurement 

subsystem parameters. 

 

2

 The majority of this rule is derived from South Coast Air Quality Management District - 

Rule 218.1 as adopted May 14, 1999 unless otherwise noted. 
218.1-2 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(d) Stack Flowmeter - The part of the CEMS that detects the 

parameters from all essential measurement sub-systems (e.g., 

temperature, static and atmospheric pressure, gas density, gas 

composition, molecular weight, gas moisture content) and 

generates signal outputs which are a function of the stack gas 

volumetric flow rate and all essential measurement sub-system 

parameters. 

(2) “Calibration” - A procedure performed to ensure that the CEMS accurately 

measures and records the concentration of the specific air contaminant or 

Diluent Gas, flow rate and other parameters necessary to generate the 

required data, as evidenced by Calibration Checks and achieved by 

periodic manual or automatic adjustment. 

(3) “Calibration Check” - A procedure performed to determine CEMS 

response to a given gaseous compound concentration by means of 

injecting a certified calibration gas mixture into the CEMS as close to the 

probe tip as practical. 

(4) “Calibration Drift” (CD) - Change in the CEMS output or response over a 

specific period of normal continuous operation when the air contaminant 

or Diluent Gas concentration at the time of the measurements is the same 

known upscale value. CD is expressed as the sum of the absolute value of 

the mean difference and the absolute value of the Confidence Coefficient 

of a series of tests, to the Full Span Range, expressed as a percentage as 

follows: 

×100

+

=

FSR

d CC

CD

Where: 

FSR = Full Span Range 

CC = Absolute value of the 95% Confidence Coefficient 

d

= Absolute value of the mean difference. The mean 

difference, d , is calculated as: 

∑=

=

n

i

di

n

d

1

1
AVAQMD RULE 218.1 218.1-3

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

Where 

∑=

n

i

di

1

= Algebraic sum of the individual differences di

n = Number of data points 

i

d = The difference between the paired response 

values of the monitoring system 

(5) “Calibration Error” (CE) 

(a) Calibration Error (as applicable to Section (D) - Standards for 

Existing CEMS) - The ratio of the difference between the air 

contaminant or Diluent Gas concentration indicated by the CEMS 

and the known concentration of the calibration gas, to the known 

concentration of the calibration gas. CE is calculated as the ratio 

of the sum of the absolute values of the mean difference and the 95 

percent Confidence Coefficient of a series of tests, to the gas 

concentration, expressed as a percentage, as follows: 

×100

+

=

C

d CC

CE

Where: 

C = Calibration gas concentration 

CC = Absolute value of the 95% Confidence Coefficient 

d = Absolute value of the mean difference. The mean 

difference is calculated as: 

∑=

=

n

i

di

n

d

1

1
218.1-4 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

Where: 

∑=

n

i

di

1

= Algebraic sum of the individual differences di

n = Number of data points 

i

d = The difference between the paired monitoring system

response value and the known gas concentration or 

the equivalent rating of the Reference Method value, 

both in units of the applicable standard 

(b) Calibration Error (as applicable to Section (C) - Standards for New 

or Modified CEMS) - The ratio of the absolute value of the 

difference between the air contaminant or Diluent Gas 

concentration indicated by the CEMS and the known concentration 

of the calibration gas, to the Full Span Range, expressed as a 

percentage, as follows: 

×100

−

=

FSR

C A

CE

Where: 

C = Calibration gas concentration 

A = Actual response or the concentration indicated by the 

monitoring system 

FSR = Full Span Range of the instrument 

(6) “CEMS Availability Percentage” - A percentage calculated as the ratio of 

the total unit operating hours for which the CEMS provided qualityassured data, to the source total unit operating hours during a specified 

period, excluding periods of Calibration, maintenance, repair, or audit, up 

to a maximum of 40 hours per month. 

(7) “Certified CEMS” - A CEMS installed, tested, operated, maintained, and 

calibrated according to the applicable requirements of Rules 218 and 

218.1; that has met the applicable performance specifications of Rule 

218.1 and, has received written approval and conditions thereto applying, 

from the APCO. 
AVAQMD RULE 218.1 218.1-5

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(8) “Certified Gas Mixture” - A gas mixture manufactured, analyzed and 

certified in accordance with the “EPA Traceability Protocol for Assay and 

Certification of Gaseous Calibration Standards” - EPA-600/R97/121, 

September 1997 Revision (EPA Traceability Protocol) or any subsequent 

version published by EPA. This definition incorporates by reference EPA 

Protocol. 

(9) “Confidence Coefficient” (CC) - The 2.5 percent error Confidence 

Coefficient for the 95 Percent Confidence Interval of a series of tests. The 

CC is calculated as follows: 

n

S

CC t

d = 975.0

Where: 

Sd = Standard deviation 

n = Number of data in a series of tests 

t0.975 = t-value (see Table of t-Values below) 

Table of t-Values* 

n t0.975 n t0.975 n t0.975

2 12.706 7 2.447 12 2.201 

3 4.303 8 2.365 13 2.179 

4 3.182 9 2.306 14 2.160 

5 2.776 10 2.262 15 2.145 

6 2.571 11 2.228 16 2.131 

*The t-values in this table are already corrected for n-1 degrees of 

freedom. Use n equal to the number of data points.

(10) “Continuous Emission Monitoring System” (CEMS) – The total combined 

equipment and systems required to continuously determine air 

contaminants and Diluent Gas concentrations and/or mass emission rate of 

a source effluent (as applicable). The CEMS consists of three (3) major 

subsystems: Sampling Interface, Analyzer and Data Acquisition System. 
218.1-6 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(11) “Continuous Monitoring” - A monitoring in which a minimum of one (1) 

measurement (e.g., concentration, mass emission, flow rate) is taken and 

recorded each minute. 

(12) “Data Acquisition System” (DAS) - The part of the CEMS that processes 

data generated by the Analyzer and records the results, thus creating a 

permanent record of the output signal in terms of concentration, flow rate, 

and any other applicable parameter necessary to generate the required data 

in units of applicable standard. The DAS consists of all equipment such as 

a computer required to convert the original recorded values to any values 

required for reporting. 

(13) “Diluent Gas” - A gas present in a calibration gas mixture or in source 

emissions that is present in quantities significantly larger than the air 

contaminant. 

(14) “Full Span Range” - The full range of values or data display output that a 

monitor component is calibrated to measure. 

(15) “Linearity Error” (LE) - The percentage error in linearity expressed in 

terms of the ratio of the absolute value of the difference between the 

reference value and the mean CEMS response value, to the reference 

value. LE is calculated as follows: 

×100

−

=

R

R C

LE

Where: 

C = Mean of the CEMS response values 

R = Certified gas concentration as reference value 

(16) “Modification Requiring Recertification” - Any change to the basic 

equipment, control equipment, contaminant concentration, interfering 

substances, or CEMS that is deemed by the APCO to have a potential for 

adversely affecting the ability of the CEMS to provide accurate, precise 

and timely data representative of the stack emissions for which the CEMS 

(or SCEMS) is required. 

(17) “Ninety-Five Percent Confidence Interval” - The statistical estimation 

denoting a range of values which is expected to include a true value with a 

95 percent probability. 

(18) “Operating Day” - Each calendar day that emissions pass through the stack 

or duct. [Derived from SCAQMD Rule 2011, Appendix A, Attachment E.] 
AVAQMD RULE 218.1 218.1-7

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(19) “Operational Period” - A minimum period of 168 continuous hours during 

which the CEMS shall operate, according to the manufacturer’s written 

performance and equipment specifications, without unscheduled 

maintenance, repair, or adjustment. 

(20) “Quality Assurance/Quality Control (QA/QC) Plan” – A written document 

in which the specific procedures for the operation, Calibration and 

maintenance of a Certified CEMS are described in detail, including 

additional quality assurance assessments and the corrective action system. 

 The purpose of this plan is to ensure that the CEMS generates, collects 

and reports valid data that is precise, accurate, complete, and of a quality 

that meets the requirements, performance specifications, and standards of 

Rules 218 and 218.1. 

(21) “Reference Method” (RM) - The official test method employed by the 

District to determine compliance with the rules or permit conditions. A 

list of Reference Methods is identified in Table 1.

(22) “Relative Accuracy” (RA) - The absolute mean difference between the gas 

concentration or emission rate determined by the CEMS and the value 

determined by the RM plus 2.5 percent error of Confidence Coefficient of 

a series of tests, divided by the mean of the RM tests. 

(23) “Relative Accuracy Audit” (RAA) - The RA test expressed in terms of the 

ratio of the relative difference between the mean Reference Method value 

and the mean CEMS response value, to the mean value determined by the 

Reference Method or applicable standard for concentration, flow or mass 

emission rate. Unless otherwise specified, RAA shall have the same 

specifications and requirements as the Relative Accuracy Test Audit 

(RATA), except that the RAA shall require a minimum of three (3) data 

sets. When a rule requires a correction of the air contaminant 

concentration to a specific O2 or CO2 concentration, the RA requirement 

shall apply to the corrected concentration value. The RA of a RAA data 

set is calculated and expressed as a percentage as follows: 

×100 −=

RM

r RM RA

Where: 

RM = Mean of the values determined by the referenced method or 

applicable standard 

r = Mean of the CEMS response values 
218.1-8 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(24) “Relative Accuracy Test Audit” (RATA) - The RA test expressed in terms 

of the ratio of the sum of the absolute mean difference between the 

CEMS-generated data and the value determined by the applicable 

Reference Method or applicable standard and the absolute Confidence 

Coefficient, to the mean of the Reference Method or applicable standard 

value for concentration, flow or mass emission rate. When a rule requires 

a correction of the air contaminant concentration to a specific O2 or CO2

concentration, the Relative Accuracy requirement shall apply to the 

corrected concentration value. The RA of a RATA data set is calculated 

and expressed as a percentage as follows: 

×100

+

=

RM

d CC

RA

Where: 

d = Absolute value of the mean difference 

CC = Absolute value of the 95% Confidence Coefficient 

RM = Average RM value or applicable standard 

The arithmetic mean of the difference, d, of a set of data is calculated as 

follows: 

∑=

=

n

i

di

n

d

1

1

Where: 

∑=

n

i

di

1

= Algebraic sum of the individual differences di

i

d = The difference between the Reference Method value and 

the CEMS value, both in units of the applicable standard 

n = Number of data points 
AVAQMD RULE 218.1 218.1-9

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(25) “Response Time” - The time interval from a step change in the air 

contaminant or gas diluent concentration to the time when 95 percent of 

the corresponding final value is reached as displayed on the CEMS data 

recorder or acquisition system. The Response Time is determined by 

introducing a Certified Gas Mixture into the CEMS upstream of the 

Sampling Interface and as close to the probe inlet as practicable. 

(26) “Routine Maintenance” - Preventive evaluation and repair (if necessary) of 

CEMS performed at specified intervals to preclude System Failure. 

Routine Maintenance may be performed as recommended by the 

manufacturer or a documented standard operating procedure determined 

through operating experience and approved by the APCO. Repairs to a 

malfunctioning system are excluded from this definition. 

(27) “Sampling Interface” - That part of the CEMS that performs sample 

acquisition using one (1) or more of the following operations: extraction, 

physical/chemical separation, transportation or conditioning of a 

representative sample from a designated source. 

(28) “Semi-Continuous Emission Monitoring System” (SCEMS) - The total 

combined equipment and systems required to semi-continuously determine 

air contaminants and Diluent Gas concentrations and/or mass emission 

rate of a source effluent (as applicable). The SCEMS consists of three (3) 

major subsystems: Sampling Interface, Analyzer and Data Acquisition 

System. This class of monitoring includes but is not limited to gas 

chromatography, integrated sensitized tape analyzer, other sample 

integration based technologies, and time-shared CEMS. 

(29) “South Coast Air Quality Management District” (SCAQMD) - The air 

quality district created pursuant to Division 26, Part 3, Chapter 5.5 of the 

California Health & Safety Code (commencing with §40400). [Derived 

from AVAQMD Rule 1124.] 

(30) “System Bias” - The difference between the gas concentrations exhibited 

by the CEMS when a calibration gas is introduced at a location upstream 

of the Sampling Interface, and as close to the sampling probe inlet as 

practicable, and when the same calibration gas is introduced directly to the 

Analyzer. 

(31) “System Failure” - Inability of the CEMS to meet the requirements of Rule 

218.1. 

(32) “Time-Sharing” - A monitoring technique where an Analyzer and possibly 

the associated sample conditioning system is used on more than one (1) 

source. 
218.1-10 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(33) “Zero Check” - A procedure performed to determine the response of the 

CEMS to a given Zero Gas standard by means of injecting the Zero Gas 

into the CEMS as close to the probe tip as practical. 

(34) “Zero Drift” (ZD) - The change in the monitoring system output/response 

over a stated period of time of normal continuous operation when the air 

contaminant or Diluent Gas concentration at the time of the measurements 

is zero. The values for ZD shall be expressed as the ratio of the sum of the 

absolute value of the mean of the difference between paired instrument 

response values and the absolute value of the CC, to the Full Span Range, 

calculated as a percentage as follows: 

×100

+

=

S

d CC

ZD

Where: 

S = Full Span Range 

CC = Absolute value of the Confidence Coefficient 

d

= Absolute value of the mean difference. The mean 

difference is calculated as: 

∑=

=

n

i

di

n

d

1

1

Where: 

∑=

n

i

di

1

= Algebraic sum of the individual differences di

n = Number of data pairs 

i

d = The difference between a pair of instrument response 

values 

(35) “Zero Gas” - A gas containing less than a specified amount of the 

contaminant or Diluent Gas which, when periodically injected into the 

CEMS, is used to check CEMS’ response to the absence of the air 

contaminant or Diluent Gas. 

(C) Standards for New or Modified CEMS 
AVAQMD RULE 218.1 218.1-11

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

In order to be a Certified CEMS, a CEMS subject to the provisions of Rule 218 

Sections (D)(1), (E)(1)(c), (E)(1)(d), (E)(2)(c) and (E)(2)(d), as applicable, shall 

meet the operational requirements, performance specifications, and standards as 

follows: [Rule 218 (E)(1)(d) removed in response to EPA comment 1b of 04/25/12 

since there is only one facility in the District with an existing CEMS currently 

subject to the provisions of this rule. This facility has indicated that they are 

compliant with the provisions of the rule and the additional time provision is not 

necessary. ]

(1) Pre-Certification Testing Requirements for New or Modified CEMS 

Before any certification or Relative Accuracy test is performed, the CEMS 

shall meet the following standards: 

(a) CEMS Location 

The CEMS shall be installed at a location that enables 

measurements of air contaminant and Diluent Gas concentration, 

and flow rates can be made which are representative of the stack 

emissions of the source. 

(b) Sampling Location 

The monitoring system sampling probe tip and the Reference 

Method sampling port locations shall be determined according to 

SCAQMD Method 1.1. The monitoring sampling probe shall be 

located where a sample may be obtained which is representative of 

the source emissions. Each probe shall not interfere with the other 

when in use. Other locations may be chosen subject to a written 

approval of the APCO. If an alternate location is chosen which 

does not conform with SCAQMD Method 1.1, the absence of flow 

disturbance shall be demonstrated using the SCAQMD method in 

the source Test Manual, Chapter X, Section 1.4 – “Alternative Site 

Selection Method,” or 40 CFR, Part 60, Appendix A, Method 1, 

Section 2.5 – “Alternative Measurement Site Selection Procedure,” 

and, the absence of stratification shall be demonstrated using the 

SCAQMD method in the source Test Manual, Chapter X, Section 

13 – “Determination of Gaseous Constituent Stratification.” 

Alternatives to sampling site selection in the presence of 

stratification are presented in Rule 218.1 (C)(3)(c)(ii). 

(c) Full Span Range (FSR) 

(i) The FSR for mass emission rate, air contaminant, diluent 

and flow analyzers shall be set such that all data points are 

within 10 to 95 percent of the range. 
218.1-12 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(ii) For air contaminant monitors, the FSR shall be set between 

150 and 200 percent of the concentration limit as specified 

in the applicable rule or permit condition. The FSR may be 

set at a value other than that specified, but no lower than 

120 percent, provided that the CEMS owner or operator 

demonstrates to the satisfaction of the APCO that the FSR 

will not be exceeded. Such demonstrations may include, 

but are not limited to, historical emissions data, historical 

process information, and historical operational information. 

 A written approval from the APCO shall be obtained

before the FSR may be modified outside of the 150 to 200 

percent of the concentration limit. 

(iii) For air contaminant monitors, a multiple-span-range may 

be required to satisfy the provisions of Sections (Cc)(i) and 

(Cc)(ii) above in situations where the normal concentration 

of the air contaminant emitted is significantly less than the 

allowable concentration limit. The CEMS shall have the 

capability to automatically change from one range to the 

other as appropriate to the monitor’s measured 

concentration. [Corrected typographical error pursuant to 

EPA comment of 4/25/12.]

(iv) For diluent monitors, the FSR shall be set such that the full 

range of O2 and CO2 concentrations can be measured. The 

FSR shall be set at 25.0 percent O2 (maximum) and 1.0 

percent CO2 (minimum) concentrations, or at a value 

approved by the APCO. 

(v) Should any data points fall below ten (10) percent of the 

FSR, those data points shall be reported according the 

following, as applicable: 

a. For CEMS with certified multiple span ranges, the 

owner shall report data that falls below 10.0 percent 

of the higher FSR and above 95 percent of the lower

FSR, at the 10.0 percent value of the higher FSR; 

b. In the event that any of the data points gathered by 

the CEMS fall below 10.0 percent of the FSR, the 

owner or operator may elect to report the 

contaminant concentrations at the 10.0 percent FSR 

value; or 

c. In the event that any data points gathered fall below 

10.0 percent of the lowest vendor guaranteed FSR 

for that CEMS (defined as the lowest FSR that the 

vendor guarantees to be capable of meeting all 

current certification requirements of Rule 218 and 

Rule 218.1, as applicable) the owner or operator 
AVAQMD RULE 218.1 218.1-13

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

may elect to use the following to measure and report 

contaminant concentrations: 

1. Report data at 10.0 percent FSR value; or 

2. Report data at actual measured value, 

provided that the CEMS meets the 

Supplemental and Alternative Performance 

Requirements in Attachment A. 

(vi) Should any data points fall above 95 percent of FSR, the 

value shall be invalid for quantification and the CEMS 

shall be considered unavailable for the purposes of

determining CEMS Availability Percentage. All excursions 

above 95 percent of FSR and the duration of these 

excursions shall be reported in the CEMS summary report 

as prescribed under Rule 218 (G). 

(d) Strip Chart Recorder 

(i) For CEMS where the strip chart recorder is used as the only 

means of data recording, the strip chart shall have a 

minimum width of at least 10 inches, a readability of 0.5 

percent of the span, and a minimum of 100 chart divisions. 

(ii) For CEMS where the strip chart recorder is used as a 

backup system or for recording data from only a single 

parameter, a strip chart of lesser size than specified in 

Section (Dd)(i) above, may be proposed in the application. 

[Corrected typographical error pursuant to EPA comment 

of 4/25/12.]

(iii) For CEMS equipped with multiple-span ranges, the chart 

recorder shall have the capability to automatically change 

span, as appropriate. 

(e) Data Acquisition System (DAS) 

(i) The DAS shall maintain all recorded data in accordance 

with Rule 218, Section (F). 

(ii) For CEMS, DAS shall acquire data from monitored 

parameters at least once every minute. 

(iii) For SCEMS, DAS shall acquire data from monitored 

parameters at least once every 15 minutes. 

(iv) DAS acquisition rate shall be set at a constant rate such that 

the data points are equally spaced. 

(v) All valid data points shall be used to determine compliance 

with applicable limit(s), and, for certification testing and 

RATA(s). 
218.1-14 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(vi) DAS sample acquisition rate during certification and 

RATA(s) shall be the same as the DAS sample acquisition 

rate during normal CEMS, or SCEMS, operation. 

(f) Operational Period 

(i) The Operational Period before any certification tests shall 

be a minimum of 168 continuous hours. 

(2) Certification Requirements and Performance Specifications for New or 

Modified CEMS 

Rule 218 Section (D)(1) provides that a series of certification tests shall be 

performed to demonstrate the acceptability of CEMS performance. The 

requirements and specifications in conducting initial certification tests 

follow: 

(a) Calibration Error (CE) Testing 

The 24-Hour CE test shall be performed at the low and high ranges, 

namely 0 to 20 and 80 to 100 percent of FSR, respectively. CE 

specifications shall be less than or equal to: 

(i) 2.5 percent of the FSR for all Analyzers; and 

(ii) 3.0 percent of the FRS of the Analyzer, for flow monitors, 

when an electronic Calibration Check is applicable. 

The 24-hour CE test shall be performed once each day as close to 

24-hour intervals as practicable, with a total of eight (8) 

consecutive tests performed. The CE specifications shall not be 

exceeded on any of the tests during the entire testing period. 

(b) Analyzer Enclosure 

(i) The Analyzer shall be contained in an environmentally 

controlled enclosure. An alarm and recording device shall 

be incorporated into the system to alert the operator to 

make corrective action should the Analyzer exceed the 

manufacturer’s recommended specifications for 

temperature drift. 

(ii) Alternatively, the owner or operator of the CEMS may 

choose to perform the 2-hour CE tests in lieu of meeting the 

Analyzer enclosure requirement in Section (C)(2)(b)(i). 

The 2-hour CE test shall be performed once every two (2) 

hours as close to 2-hour intervals as practicable, with total 

of thirteen consecutive tests performed. The 2-hr CE test 

shall be performed when ambient temperature is expected 

to vary diurnally at least 30°F. The test shall be performed 
AVAQMD RULE 218.1 218.1-15

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

at the low and high ranges of FSR, namely 0 to 20 and 80 

to 100 percent, respectively. The specifications in Sections 

(C)(2)(a)(i) and (ii) shall apply to 2-hour CE. 

(iii) The owner or operator of the CEMS may qualify for an 

exemption from Section (C)(2)(b)(i) to provide 

environmental controls for the Analyzer enclosure by 

demonstrating, to the satisfaction of the APCO, that the 

CEMS is located: 

a. In a geographic area where seasonal high and low

temperatures do not exceed the operational 

temperature specifications for the Analyzer; 

b. In a geographic area where monthly maximum 

temperature variation is less than 30°F for all 

months of the year; and 

c. The CEMS is located in a site that is protected from 

radiation and convection heating sources. 

(c) Relative Accuracy 

RATA shall be performed for raw contaminant concentration, and 

if applicable, for corrected concentration, emission rate, O2

concentration, CO2 concentration analyzers, and stack and fuel 

flow monitors. There shall be a minimum of nine (9) sets of test 

data generated. If the number of tests exceeds nine (9) sets, data 

may be discarded if it is identified as an outlier by the technical 

guidance set forth by the APCO, or for valid reasons (e.g., process 

upsets, CEMS malfunction, etc.) which must be substantiated with 

appropriate documentation and subject to approval by the APCO. 

All data collected shall be submitted to the APCO. The CEMS 

shall meet the following RA performance specifications: 

(i) Less than or equal to 20.0 percent of the mean value of the 

Reference Method for pollutant concentrations, or the de 

minimus concentration as follows, whichever is greater: 

[NOx and CO de minimis concentration dropped per 

recommendation in SCAQMD Rule 218.1 EPA TSD, March 

18, 2010.]

Pollutant De minimus Concentration 

SO2 2.0 ppm 

Reduced sulfur compounds 4.0 ppm 

(ii) Less than or equal to 10.0 percent of the mean value of the 

Reference Method for diluent concentrations, or the de 

minimus value of 1.0 percent O2, whichever is greater. 
218.1-16 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(iii) Less than or equal to 15.0 percent of the mean value of the 

Reference Method for flow monitors, or the de minimus 

value equivalent to a calculated volumetric flow rate based 

on two (2) feet per second stack gas velocity for cases 

where the mean stack gas velocity obtained by the 

Reference Method test is less than 15 feet per second. 

(iv) Less than or equal to 20.0 percent of the mean value of the 

Reference Method for mass emission rates, or the de

minimus value equivalent to a calculated mass emission 

rate based on two (2) feet per second stack gas velocity for 

cases where the mean stack gas velocity obtained by the 

Reference Method test is less than 15 feet per second. 

The Relative Accuracy requirement may be met if the

average of the differences between the CEMS measured 

data and the Reference Method test data plus the 

Confidence Coefficient is less than or equal to the Relative 

Accuracy de minimus value. 

(3) Relative Accuracy Test Requirements for New or Modified CEMS 

Within fourteen days of, or during all Relative Accuracy tests, the CEMS 

shall meet the following requirements, except those that may be waived as 

allowed in Rule 218.1, Section (C)(4)(c): 

(a) Response Time 

The Response Time for CO CEMS shall not exceed 1.5 minutes 

except where there is a technical limitation, in which case the 

Response Time shall be five (5) minutes. The Response Time for 

all other CEMS and flow monitors, as applicable, shall not exceed 

five (5) minutes. 

(b) Calibration Error 

The CE testing requirements are specified in Section (C)(2)(a). 

(c) Concentration Stratification 

(i) The owner or operator shall demonstrate the absence of 

stratification through testing performed according to the 

method in Chapter X, Section 13 - “Non-Standard Methods 

and Techniques”, of the SCAQMD Source Testing Manual. 

 The number of tests shall be determined as follows: 

a. Test(s) shall be conducted at one (1) load level if 

the owner or operator demonstrates to the 

satisfaction of the APCO that the equipment 
AVAQMD RULE 218.1 218.1-17

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

operates within a 20 percent load range for at least 

80 percent of the time; 

b. Test(s) shall be conducted at two (2) different load 

levels if the owner or operator demonstrates to the

satisfaction of the APCO that the equipment 

operates within a 50 percent load range for at least 

80 percent of the time; or, 

c. Test(s) shall be conducted at three (3) different load 

levels if the equipment operates outside of the 

criteria in Sections (C)(3)(c)(i)[a] and [b]. 

The absence of stratification is considered verified 

if the difference between the highest measured 

concentration (time normalized) and the lowest 

measured concentration (time normalized) divided 

by the average measured concentration (time 

normalized), when expressed as a percentage, is less 

than or equal to 10 percent. Upon verification of 

the absence of stratification, the owner or operator 

may position the CEMS sampling probe at any point 

within the stack with the exception of those points

that are adjacent to the stack wall. The CEMS 

sampling probe should be located in the stack at 

least one-third of the stack diameter. The RM for 

RATA may be conducted at a single point within 

the stack that is not adjacent to the stack wall and 

does not interfere with the sampling and the 

operation of the facility CEMS. 

(ii) Should testing demonstrate the presence of stratification, 

the owner or operator may elect one (1) of the following 

alternatives: 

a. If the stratification is greater than ten (10) percent 

but the difference between the highest measured 

concentration (time normalized) and the lowest 

measured concentration (time normalized) is less 

than or equal to 1.0 ppmv: 

1. Then the CEMS sampling probe may be 

located at any point within the stack except 

any points that is adjacent to the stack or 

adjacent to the highest measured 

concentration (time normalized) and the 
218.1-18 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

lowest measured concentration (time 

normalized); or 

2. If it is not possible to avoid using a point 

adjacent to either the highest measured 

concentration (time normalized) or the 

lowest measured concentration (time 

normalized), then locate the CEMS 

sampling probe such that the placement 

minimizes the difference between the 

concentration at the proposed probe location 

and the concentration at the point of highest 

measured concentration (time normalized) 

or the lowest measured concentration (time 

normalized). 

b. Determine a representative CEMS probe location 

such that the following criteria are met: 

1. All traverse point concentrations are within 

10.0 percent of the average of all traverse 

point concentrations (time normalized), or, 

the difference is less than or equal to 1.0 

ppm, whichever is greater; 

2. There exists at least one (1) traverse point 

concentration (Xr), not located next to the 

stack or duct wall, that is less than or equal 

to 10.0 percent each adjacent traverse point 

concentration of Xr, or the difference is less 

than or equal to 1.0 ppm, whichever is 

greater; and 

3. The CEMS probe is located at (or as near as 

practical) Xr with minimum adjacent 

traverse point concentration fluctuations as 

determined in Section (C)(3)(c)(ii)[b][2], 

above. 

c. Determine a representative multiple point sampling 

configuration as approved by the APCO, following 

the guidance document by Emission Measurement 

Technical Information Center, “Evaluation 

Procedure for Multi-Hole Sample Probes” (EMTIC 

GD-031). 
AVAQMD RULE 218.1 218.1-19

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

d. Modify the stack and/or CEMS sampling probe 

location and retest for the absence of stratification. 

(d) Cyclonic Flow 

The owner or operator shall perform tests to verify the absence of 

cyclonic flow for the CEMS and Reference Method sampling 

probes. The cyclonic flow test shall be required when measuring 

mass emission rates and shall be performed according to the 

SCAQMD method in the Source Test Manual, Chapter X: NonStandard Methods and Techniques following the testing conditions 

of Section (C)(3)(c)(i)[a], [b] or [c], as applicable. 

(e) Interference 

The owner or operator shall perform tests to verify the absence of 

sampling, analytical and flow interference, as applicable. 

(f) Linearity Error 

LE tests shall be performed at the low, middle and high ranges of 

concentration, namely 20 to 30, 50 to 60, and 80 to 100 percent. 

Each calibration gas shall be introduced into the CEMS three (3) 

times. The same gas shall not be used twice in succession. LE 

shall be less than or equal to 5.0 percent of the calibration gas 

concentration. 

(g) Multiple-Span-Range 

For CEMS that have multiple-span-range, all certification tests 

shall be performed at the lowest range. Except for RA and 

interference tests, all other certification tests shall be performed on 

other ranges. 

(4) Operational Requirements and Performance Specifications for New or 

Modified CEMS 

After final approval, the CEMS shall be subsequently operated and 

maintained according to the following requirements and specifications: 

(a) 24-Hour CE 

CE tests shall be performed once each Operating Day as close to 

24 hour intervals as practicable at the low (0 to 20 percent) and 

high (80 to 100 percent) ranges of concentration. CE test results 

which are greater than the limits specified in Sections (C)(2)(a)(i) 

and (ii), but less than or equal to 5.0 percent of the Full Span 
218.1-20 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

Range shall be addressed by QA/QC Plan remediation. The CEMS 

shall be deemed out-of-control during such period when any CE 

test result is greater than the specified limits and greater than 5.0 

percent of the Full Span Range, until the CE test meets the 

specifications. All data generated by the CEMS during an out-ofcontrol period shall be deemed invalid but shall not be deleted or 

excluded from the records or database. 

(b) System Bias Test 

A System Bias shall be conducted every 12 months in conjunction 

with Relative Accuracy Audit required under Rule 218.1 Section 

(C)(4)(c). The CEMS System Bias shall not exceed ±5.0 percent 

of the Full Span Range for contaminant Analyzers. In addition, the 

owner or operator shall include in the facility QA/QC Plan, criteria 

for excessive drift (e.g. control limits on cumulative drift) and 

appropriate diagnostic techniques to identify sources of Analyzer 

drift and System Bias when control limits are exceeded. 

(c) Relative Accuracy Testing 

RATA and RAA, as applicable, shall be performed at least once 

every 12 months. The test shall be completed annually no later 

than the end of the calendar quarter in which the date of the 

original certification test was performed. During any Relative 

Accuracy tests after CEMS certification, the owner or operator may 

request a waiver from stratification, cyclonic flow, and/or 

interference requirements in Sections (C)(3)(c), (d) and (e), 

respectively, by submitting to the APCO, for approval, any 

applicable documentation or previous test or historical data that 

meets the stratification, cyclonic flow, and/or interference 

requirements. 

(d) Cylinder Gas Audit (CGA) 

A CGA shall be performed every calendar quarter but in no more 

than three (3) quarters in succession. The CGA shall be conducted 

according to the provisions of 40 CFR 60, Appendix F. The audit 

gases shall be according to the certification requirements of Rule 

218.1. 

(e) The APCO may require recertification of the CEMS if the annual 

availability percentage is below 95 percent. Annual CEMS 

Availability Percentage calculations will be based on the year 

ending on the last day of the calendar quarter in which the CEMS 

was originally certified. 
AVAQMD RULE 218.1 218.1-21

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(f) The owner or operator of a CEMS that requires moisture correction 

in reporting flow and concentration shall measure and monitor 

moisture in the stack gas used for emission data calculations in 

accordance with the written technical guidance document set forth 

by the APCO. Alternatively, with APCO approval, for equipment 

whose moisture source is only from fuel combustion, the operator 

may calculate the moisture content using fuel properties and 

ambient air humidity data or, for processes that saturate the exhaust 

gas with moisture, such as a wet scrubber system, the operator may 

use the saturation temperature for moisture content data. 

(D) Standards for Existing CEMS 

In order to be a Certified CEMS, a CEMS subject to the provisions of Rule 218 

Sections (E)(1) and (E)(2), shall meet the following operational requirements and 

performance specifications, and the standards of Rule 218.1 Section (E): 

(1) Performance Specifications for Existing Gaseous Air Contaminant CEMS 

 Parameter Specifications 

(a) Operational Period Greater than or equal to 168 hours 

(b) Calibration Error Less than or equal to five (5) percent of 

the calibration gas value 

(c) Response Time Less than or equal to ten (10) minutes 

(d) Zero Drift (2-hour) Less than or equal to two (2) percent of 

FSR 

(e) Zero Drift (24-hour) Less than or equal to two (2) percent of 

FSR 

(f) Calibration Drift (2-hour) Less than or equal to two (2) percent of 

FSR 

(g) Calibration Drift (24-hour) Less than or equal to 2.5 percent of 

FSR 

(h) Relative Accuracy Less than or equal to 20 percent of the 

mean value of the RM test data, or, less 

than or equal to 10 percent of the 

allowed concentration, whichever is 

greater 
218.1-22 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(2) Performance Specifications for Existing Diluent Gas CEMS 

 Parameter Specifications 

(a) Operational Period Greater than or equal to 168 hours 

(b) Calibration Error Less than or equal to five (5) 

percent of the calibration gas value 

(c) Response Time Less than or equal to ten (10) 

minutes 

(d) Zero Drift (2-hour) Less than or equal to 0.4 percent 

CO2 or O2

(e) Zero Drift (24-hour) Less than or equal to 0.5 percent 

CO2 or O2

(f) Calibration Drift (2-hour) Less than or equal to 0.4 percent 

CO2 or O2

(g) Calibration Drift (24-hour) Less than or equal to 0.5 percent 

CO2 or O2

(3) Full Span Range for Existing CEMS 

The instrument FSR shall be equivalent to approximately 200 percent of 

the concentration limit as specified in the applicable rule, or at a value 

approved by the APCO. O2 and CO2 instrument full span readings shall be 

such that the full range of concentrations encountered can be measured. 

(4) Cycle of Operation for Existing CEMS 

The CEMS shall complete a minimum of one (1) cycle of operation 

(sampling, analyzing and data recording), for each successive 15 minute 

period. 

(E) Standards, Specifications and Requirements for New, Modified and 

Existing CEMS: 

(1) Calibration Gas 

(a) Calibration gas mixtures, as defined in Rule 218.1 (B)(8), shall be 

manufactured, analyzed and certified in accordance with the “EPA 

Traceability Protocol for Assay and Certification of Gaseous 

Calibration Standards” - EPA-600/R97/121, September 1997 
AVAQMD RULE 218.1 218.1-23

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

Revision (EPA Protocol). The certification period and 

recertification requirements, as applicable, shall be according to the 

EPA Protocol. 

(b) For gas calibration standards not explicitly covered by the EPA 

Protocol, the CEMS owner or operator shall submit the gas 

manufacturer’s alternative certification protocol for the specific 

compound or compounds. 

(i) The procedures of the EPA Protocol shall be used for gas 

calibration standards not explicitly covered therein, except 

that the gas manufacturer must identify a recertification 

period and submit data documenting the applicability of 

this period. The gas manufacturer may submit alternative 

performance standards for certification and recertification, 

based on supporting technical data also provided by the 

manufacturer. This alternative shall be subject to the 

approval of APCO. 

(ii) If there is no existing National Institute of Standards and 

Technology (NIST) standard for the measured parameter, 

the gas manufacturer may submit an alternative reference 

standard and the supporting technical data that define the 

stability, accuracy, and precision of the alternative reference 

standard. This alternative shall be subject to the approval 

of APCO. 

(iii) The CEMS owner or operator may submit an alternative 

protocol to the EPA Protocol, provided that the CEMS 

owner or operator demonstrates through supporting 

technical data that the procedures therein are not applicable 

to the constituent in the calibration gas standard being 

certified. This alternative shall be subject to the approval 

of APCO. 

(c) Compressed and/or filtered air, such as instrument air, may also be 

used in lieu of oxygen span gas provided that the CEMS owner or 

operator demonstrates, to the satisfaction of the APCO, that it is of 

equivalent quality to the calibration gas standards above. As part 

of such documentation, the owner or operator shall include in their 

QA/QC plan the process or operation in producing such 

compressed and/or filtered air and periodically checking that 

compressed air and/or filtered air continues to meet the calibration 

gas standards. 

(2) Zero Gas 

Zero Gases used shall meet the following criteria: 
218.1-24 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(a) For gaseous air contaminant monitors, the Zero Gas shall be 

certified by the manufacturer to contain no more than 0.1 ppm of 

the air contaminant analyzed by the subject monitor or 1.0 percent 

of the applicable standard, whichever is less. 

(b) For carbon monoxide (CO) monitors, the Zero Gas shall be 

certified by the manufacturer to contain less than 0.5 ppm carbon 

CO or 1.0 percent of the applicable standard, whichever is less. 

(c) For CO2 and O2 monitors, the Zero Gas shall be certified by the 

manufacturer to contain less than 1.0 ppm CO2 or O2. 

(d) Compressed and/or filtered air, such as instrument air, may also be 

used in lieu of Zero Gas provided that the CEMS owner or operator 

demonstrates, to the satisfaction of the APCO, that it is of 

equivalent quality to the above Zero Gas standards. As part of 

such documentation, the owner or operator shall include in their 

QA/QC plan the process or operation in producing such 

compressed and/or filtered air and periodically checking that 

compressed air and/or filtered air continues to meet the Zero Gas 

standards. 

(3) Automatic Calibration Data 

If automatic adjustments to the monitor settings are made, conduct the 

calibration tests in a way that the magnitude of the adjustments can be 

determined and recorded. 

(4) F-Factors 

The owner or operator shall use in the CEMS calculations the Fd factors 

listed in 40 CFR Part 60, Appendix A, Method 19, Table 19-1, as 

applicable. When alternative fuels are fired, the owner or operator shall 

submit data to develop Fd factors and obtain APCO approval. 

(5) NO2 to NO Conversion Efficiency 

The conversion efficiency tests shall be conducted according to the 

requirements of SCAQMD Method 100.1. The value for the NO2 gas 

shall be greater than or equal to the maximum expected or recorded NO2

and greater than or equal to 20 percent of the FSR.

(F) Time-Sharing Requirements 

A time-shared CEMS for which an application is submitted after [date of 

adoption] shall meet all of the performance specifications as well as the following 

requirements: 
AVAQMD RULE 218.1 218.1-25

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

(1) All sources shall have mutually compatible range(s) of air contaminant 

gases at all times. 

(2) Each source shall have a data-reading period, at a minimum, equal to three 

(3) times the longest Response Time of the system. For shared systems 

the Response Time is measured at the input or probe at each source. A 

demonstration of Response Time for each source shall be made during 

certification testing. Data are not to be collected following a switch of 

sample sources until a period of time equal to one (1) Response Time has 

passed. 

(3) The CEMS shall be capable of performing and recording zero and span 

calibrations at each source, including the calibration factors and correction 

values before and after every automatic Calibration. 
AVAQMD RULE 218.1 218.1-26

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

Table 1 

REFERENCE METHODS 

RULE 218.1 

SCAQMD Method 1.1 Sample and Velocity Traverses for Stationary Sources 

SCAQMD Method 1.2 Sample and Velocity Traverses for Stationary Sources with 

Small Stack or Ducts 

SCAQMD Method 2.1 Determination of Stack Gas Velocity and Volumetric Flow 

Rate (S-type Pitot tube) 

SCAQMD Method 2.2 Direct Measurement of Gas Volume through Pipes and 

Small Ducts 

SCAQMD Method 2.3 Determination of Gas Velocity and Volumetric Flow Rate 

from Small Stacks or Ducts 

SCAQMD Method 3.1 Gas Analysis for Dry Molecular Weight and Excess Air 

SCAQMD Method 4.1 Determination of Moisture Content in Stack Gases 

SCAQMD Method 6.1 Determination of Sulfuric Acid and Sulfur Oxides from 

Stationary Sources 

SCAQMD Method 7.1 Determination of Nitrogen Oxide Emissions for Stationary 

Sources 

SCAQMD Method 100.1 Instrumental Analyzer Procedures for Continuous Gaseous 

Emission Sampling 

SCAQMD Method 307.91 Determination of Sulfur in a Gaseous Matrix 

EPA Method 6 Determination of Sulfur Dioxide Emissions from 

Stationary Sources 

EPA Method 19 Determination of Sulfur Dioxide Removal Efficiency and 

Particulate, Sulfur Dioxide and Nitrogen Oxides Emission 

Rates from Electric Utility Steam Generator (40 CFR Part 

60 Appendix A) 

ASTM Method D 4294-03 or 

D 2622-82

Determination of Sulfur in Liquid FuelsStandard Test 

Method for Sulfur in Petroleum and Petroleum Products by 

Energy Dispersive X-Ray Fluorescence Spectrometry 

[Added complete method title as well as most recent
AVAQMD RULE 218.1 218.1-27

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

approved EPA version per EPA comment of 4/255/12.] 

ASTM Method D2622 -05 Standard Test Method for Sulfur in Petroleum Products by 

Wavelength Dispersive X-ray Fluorescence Spectrometry 

[Added complete method title as well as most recent

approved EPA version per EPA comment of 4/25/12.]
218.1-28 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

ATTACHMENT A 

SUPPLEMENTAL AND ALTERNATIVE 

CEMS PERFORMANCE REQUIREMENTS 

(A) Applicability of Supplemental and Alternative Performance 

Requirements 

The CEMS operator who elects (or who may be required) to measure 

concentrations that fall below 10 percent of the lowest vendor guaranteed full 

scale span range, shall satisfy the performance requirements as specified in Table 

A-1 listed below. 

TABLE A-1 

Alternative Performance Requirement(s) 

CEMS Certified per 

Rule 218.1 

Yes or No

Performance Requirement(s) 

LLSR/BFD HLSR/BFD LLR/BFD LLCE 

Yes X + X 

No X X + X 

(1) + (plus) denotes an additional performance requirement that shall be 

conducted if the mandatory performance requirement(s) cannot be met. 

(2) If the concentration of the CEMS is such that the specifications for the low 

level spike recovery/bias factor determination cannot be met, the Facility 

Permit holder shall conduct a low level RATA/bias factor determination. 

(3) Abbreviations used in this Attachment are: 

Low Level Spike Recovery/Bias Factor Determination (LLSR/BFD) 

High Level Spike Recovery/Bias Factor Determination (HLSR/BFD) 

Low Level RATA/Bias Factor Determination (LLR/BFD) 

Low Level Calibration Error (LLCE) 

Relative Accuracy Test Audit (RATA) 

Relative Accuracy (RA) 

National Institute of Standards Traceability (NIST)

(B) Test Definitions, Performance Specifications and Test Procedures 

This section explains in detail how each performance requirement is to be 

conducted. 

(1) Low Level Calibration Error 
AVAQMD RULE 218.1 218.1-29

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

The low level Calibration Error test is defined as challenging the CEMS 

(from probe to monitor) with certified calibration gases (e.g., NO in N2) at 

three (3) levels in the 0-20 percent Full Span Range. Since Certified Gas 

Mixtures or standards may not be available at the concentrations required 

for this test, gas dilution systems may be used, with District approval, if 

they are used according to either District or EPA protocols as specified in 

Rule 218.1, for the verification of gas dilution systems in the field. The 

CEMS high-level calibration gas may be diluted for the purpose of 

conducting the low level Calibration Error test. 

(a) Performance Specifications 

Introduce pollutant concentrations at approximately the 20 percent, 

10 percent, and 5 percent of full span levels through the normal 

CEMS Calibration system. No low level Calibration Error shall 

exceed 2.5 percent of full scale span. 

(b) Testing Procedures 

(i) Perform a standard zero/span check; if zero or span check 

exceeds 2.5 percent full span, adjust monitor and redo 

zero/span check. 

(ii) After zero/span check allow the CEMS to sample stack gas 

for at least 15 minutes. 

(iii) Introduce any of the low level Calibration Error standards 

through the CEMS Calibration system. 

(iv) Read the CEMS response to the calibration gas starting no 

later than three (3) system Response Times after 

introducing the calibration gas; the CEMS response shall be 

averaged for at least three (3) Response Times and for no 

longer than six (6) Response Times. 

(v) After the low level Calibration Error check allow the 

CEMS to sample stack gas for at least 15 minutes. 

(vi) Repeat steps (iii) through (v) until all three (3) low level 

Calibration Error checks are complete. 

(vii) Conduct post test calibration and Zero Checks. 

(2) Spike Recovery and Bias Factor Determinations 

Spiking is defined as introducing known concentrations of the pollutant of 

interest (e.g., gas standard to contain a mixture of NO and NO2 is 

representative of the ratio of NO and NO2 in stack gas) and an appropriate 

non-reactive, noncondensable and non-soluble tracer gas from a single 

cylinder (EPA Protocol as specified in Rule 218.1 or NIST traceable to 

two (2) percent analytical accuracy if no EPA Protocol is available) near 

the probe and upstream of any sample conditioning systems, at a flow rate 

not to exceed 10 percent of the total sample gas flow rate. The purpose of 
218.1-30 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

the 10 percent limitation is to ensure that the gas matrix (water, CO2, 

particulates, interferences) is essentially the same as the stack gas alone. 

The tracer gas is monitored in real time and the ratio of the monitored 

concentration to the certified concentration in the cylinder is the dilution 

factor. The expected pollutant concentration (dilution factor times the 

certified pollutant concentration in the cylinder) is compared to the 

monitored pollutant concentration. 

(3) High Level Spike Recovery/Bias Factor Determination 

The high level spike recovery/bias factor determination is used when it is 

technologically not possible to certify the CEMS per the standard Rule 

218.1 requirements. The spiking facility/interface shall be a permanently 

installed part of the CEMS sample acquisition system and accessible to the 

APCO as well as the CEMS operator. 

(a) Performance Specifications 

The CEMS shall demonstrate a RA ≤20 percent, where the spike value is 

used in place of the Reference Method in the normal RA calculation, as 

described below. 

(b) Testing Procedures 

(i) Spike the sample to the CEMS with a calibration standard 

containing the pollutant of interest and CO or other nonsoluble, non-reacting alternative tracer gas (alternative 

tracer gas) at a flow rate not to exceed 10 percent of the 

CEMS sampling flow rate and of such concentrations as to 

produce an expected 40-80 percent of full scale span for the 

pollutant of interest and a quantifiable concentration of CO 

(or alternative tracer gas) that is at least a factor of 10 

higher than expected in the unspiked stack gas. The 

calibration standards for both pollutants of interest and CO 

(or alternative tracer gas) must meet Rule 218.1 

requirements. 

(ii) Monitor the CO (or alternative tracer gas) using an 

appropriate continuous (or semi-continuous if necessary) 

monitor meeting the requirements of SCAQMD Method 

100.1 and all data falling within the 10-95 percent full scale 

span, and preferably within 30-70 percent full scale span. 

[Clarified that this is a SCAQMD method pursuant to EPA 

comment of 4/25/12.]

(iii) Alternate spiked sample gas and unspiked sample gas for a 

total of nine (9) runs of spiked sample gas and ten runs of 

unspiked sample gas. Sampling times should be 
AVAQMD RULE 218.1 218.1-31

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

sufficiently long to mitigate Response Time and averaging 

effects. 

(iv) For each run, the average CEMS reading must be between 

40 percent full scale span and 80 percent full scale span. If 

not, adjust spiking as necessary and continue runs, but 

expected spike must represent at least 50 percent of the 

total pollutant value read by the CEMS. 

(v) Calculate the spike recovery for both the pollutant and the 

CO (or alternative tracer gas) for each run by first averaging 

the pre- and postspike values for each run and subtracting 

that value from the spiked value to yield nine (9) values for 

recovered spikes. 

(vi) Using the CO (or alternative tracer gas) spike recovery 

values for each run and the certified CO (or alternative 

tracer gas) concentration, calculate the dilution ratio for 

each run. Multiply the certified pollutant concentration by 

the dilution factor for each run to determine the expected 

diluted pollutant concentrations. Using the expected 

diluted concentrations as the “Reference Method” value, 

calculate the Relative Accuracy. The RA shall be ≤20 

percent. 

(4) Low Level Spike Recovery/Bias Factor Determination 

The low-level spike recovery/bias factor determination is used to 

determine if a significant bias exists at concentrations near the 10 percent 

full scale span level. The spiking facility/interface shall be a permanently 

installed part of the CEMS sample acquisition system and accessible to the 

APCO staff as well as the CEMS operator. 

(a) Performance Specifications 

There are no pass/fail criteria with respect to the magnitude of the 

percent Relative Accuracy. There are performance criteria for the 

range of concentration on the CEMS the extent to which the spike 

must be greater than the background pollutant level. 

(b) Testing Procedures 

(i) Spike the sample to the CEMS with a calibration standard 

containing the pollutant of interest and CO or other nonsoluble, non-reacting alternative tracer gas (alternative 

tracer gas) at a flow rate not to exceed 10 percent of the 

CEMS sampling flow rate and of such concentrations as to 

produce an expected 10-25 percent of full scale span for the 

pollutant of interest and a quantifiable concentration of CO 

(or alternative tracer gas) that is at least a factor of 10 
218.1-32 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

higher than expected in the unspiked stack gas. The 

calibration standards for both pollutants of interest and CO 

(or alternative tracer gas) must meet Rule 218.1 

requirements. 

(ii) Monitor the CO (or alternative tracer gas) using an 

appropriate continuous (or semi-continuous if necessary) 

monitor meeting the requirements of SCAQMD Method 

100.1 and all data falling within the 10-95 percent full scale 

span, and preferably within 30-70 percent full scale span. 

[Clarified that this is a SCAQMD method pursuant to EPA 

comment of 4/25/12.]

(iii) Alternate spiked sample gas and unspiked sample gas for a 

total of nine (9) runs of spiked sample gas and ten runs of 

unspiked sample gas. Sampling times should be 

sufficiently long to mitigate Response Time and averaging 

effects. 

(iv) For each run, the average CEMS reading must be below 25 

percent full scale span and >10 percent full scale span. If 

not, adjust spiking as necessary and continue runs; but 

expected spike must represent at least 50 percent of the 

total pollutant value read by the CEMS. 

(v) Calculate the spike recovery for both the pollutant and the 

CO (or alternative tracer gas) for each run by first averaging 

the pre- and post-spike values for each run and subtracting 

that value from the spiked value to yield nine (9) values for 

recovered spikes. 

(vi) Using the CO (or alternative tracer gas) spike recovery 

values for each run and the certified CO (or alternative 

tracer gas) concentration, calculate the dilution ratio for 

each run. Multiply the certified pollutant concentration by 

the dilution factor for each run to determine the expected 

diluted pollutant concentrations. Using the expected 

diluted concentrations as the “Reference Method” value, 

calculate the Relative Accuracy as specified in Rule 218.1. 

If the average difference is less than the Confidence 

Coefficient then no low level bias factor is applied. If the 

average difference is greater than the Confidence 

Coefficient and the average expected spike is less than the 

average CEMS measured spike, then no low level bias

factor is applied. If the average difference is greater than 

the Confidence Coefficient and the average expected spike 

is greater than the average CEMS measured spike, then a 

low level bias factor equal to the absolute value of the 

average difference is added to data reported at or below the 

10 percent of full scale span. 
AVAQMD RULE 218.1 218.1-33

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

(5) Low Level RATA/Bias Factor Determination using Enhanced Reference 

Method 6.1 

A low level RATA/bias factor determination is designed to determine if 

there exists a statistically significant bias at low level concentrations. It 

consists of nine (9) test runs that measure the stack concentration and the 

CEMS concentration concurrently. 

(a) Performance Specifications 

There are no pass/fail criteria with respect to the magnitude of the 

percent Relative Accuracy. There are performance criteria for the 

special RATA with respect to the Reference Method and range of 

concentration on the CEMS. 

(b) Testing Procedures 

The Reference Method for the low level RATA/bias factor 

determination is SCAQMD Method 100.1 

(i) Perform a minimum of nine (9) runs of low level RATA for 

CEMS versus the Reference Method at actual levels 

(unspiked). 

(ii) The full scale span range for the Reference Method shall be 

such that all data falls with 20 - 95 percent of full scale 

span range. 

(iii) The Reference Method shall meet all SCAQMD Method 

100.1 performance criteria. [Clarified that this is a 

SCAQMD method pursuant to EPA comment of 4/25/12.]

(iv) Calculate the average difference (d = CEMS - Reference 

Method, ppm) and Confidence Coefficient (cc = statistical 

calculated, ppm). 

(v) If d > 0 then the bias = 0 ppm; if d < 0 and |d| > cc then bias 

= d; if d <0 and |d| < cc then bias = 0 ppm. 

(C) Testing Frequency 

For each CEMS, perform the aforementioned performance requirements once a 

year thereafter. These annual assessments shall be completed within six (6) 

months of the end of the calendar quarter in which the CEMS was originally 

certified. 
218.1-34 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D3: 06/06/12 

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218.1-35 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

ATTACHMENT A 

SUPPLEMENTAL AND ALTERNATIVE 

CEMS PERFORMANCE REQUIREMENTS 

(A) Applicability of Supplemental and Alternative Performance Requirements 

The CEMS operator who elects (or who may be required) to measure concentrations that 

fall below 10 percent of the lowest vendor guaranteed full scale span range, shall satisfy 

the performance requirements as specified in Table A-1 listed below. 

TABLE A-1 

Alternative Performance Requirement(s) 

CEMS Certified 

per 

Rule 218.1 

Yes or No

Performance Requirement(s) 

LLSR

/BFD 

HLS

R/BF

D 

LL

R/B

FD 

LL

CE 

Yes X + X 

No X X + X 

(1) + (plus) denotes an additional performance requirement that shall be conducted if 

the mandatory performance requirement(s) cannot be met. 

(2) If the concentration of the CEMS is such that the specifications for the low level 

spike recovery/bias factor determination cannot be met, the Facility Permit holder 

shall conduct a low level RATA/bias factor determination. 

(3) Abbreviations used in this Attachment are: 

Low Level Spike Recovery/Bias Factor Determination (LLSR/BFD) 

High Level Spike Recovery/Bias Factor Determination (HLSR/BFD) 

Low Level RATA/Bias Factor Determination (LLR/BFD) 

Low Level Calibration Error (LLCE) 

Relative Accuracy Test Audit (RATA) 

Relative Accuracy (RA) 

National Institute of Standards Traceability (NIST)

(B) Test Definitions, Performance Specifications and Test Procedures 

This section explains in detail how each performance requirement is to be conducted. 
218.1-36 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

(1) Low Level Calibration Error 

The low level Calibration Error test is defined as challenging the CEMS (from 

probe to monitor) with certified calibration gases (e.g., NO in N2) at three (3) 

levels in the 0-20 percent Full Span Range. Since Certified Gas Mixtures or 

standards may not be available at the concentrations required for this test, gas 

dilution systems may be used, with District approval, if they are used according to 

either District or EPA protocols as specified in Rule 218.1, for the verification of 

gas dilution systems in the field. The CEMS high-level calibration gas may be 

diluted for the purpose of conducting the low level Calibration Error test. 

(a) Performance Specifications 

Introduce pollutant concentrations at approximately the 20 percent, 10 

percent, and 5 percent of full span levels through the normal CEMS 

Calibration system. No low level Calibration Error shall exceed 2.5 

percent of full scale span. 

(b) Testing Procedures 

(i) Perform a standard zero/span check; if zero or span check exceeds 

2.5 percent full span, adjust monitor and redo zero/span check. 

(ii) After zero/span check allow the CEMS to sample stack gas for at 

least 15 minutes. 

(iii) Introduce any of the low level Calibration Error standards through 

the CEMS Calibration system. 

(iv) Read the CEMS response to the calibration gas starting no later 

than three (3) system Response Times after introducing the 

calibration gas; the CEMS response shall be averaged for at least 

three (3) Response Times and for no longer than six (6) Response 

Times. 

(v) After the low level Calibration Error check allow the CEMS to 

sample stack gas for at least 15 minutes. 

(vi) Repeat steps (iii) through (v) until all three (3) low level 

Calibration Error checks are complete. 

(vii) Conduct post test calibration and Zero Checks. 

(2) Spike Recovery and Bias Factor Determinations 

Spiking is defined as introducing known concentrations of the pollutant of interest 

(e.g., gas standard to contain a mixture of NO and NO2 is representative of the 

ratio of NO and NO2 in stack gas) and an appropriate non-reactive, 

noncondensable and non-soluble tracer gas from a single cylinder (EPA Protocol 

as specified in Rule 218.1 or NIST traceable to two (2) percent analytical accuracy 

if no EPA Protocol is available) near the probe and upstream of any sample 
AVAQMD RULE 218.1 218.1-37

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

conditioning systems, at a flow rate not to exceed 10 percent of the total sample 

gas flow rate. The purpose of the 10 percent limitation is to ensure that the gas 

matrix (water, CO2, particulates, interferences) is essentially the same as the stack 

gas alone. The tracer gas is monitored in real time and the ratio of the monitored 

concentration to the certified concentration in the cylinder is the dilution factor. 

The expected pollutant concentration (dilution factor times the certified pollutant 

concentration in the cylinder) is compared to the monitored pollutant 

concentration. 

(3) High Level Spike Recovery/Bias Factor Determination 

The high level spike recovery/bias factor determination is used when it is 

technologically not possible to certify the CEMS per the standard Rule 218.1 

requirements. The spiking facility/interface shall be a permanently installed part 

of the CEMS sample acquisition system and accessible to the APCO as well as the 

CEMS operator. 

(a) Performance Specifications 

The CEMS shall demonstrate a RA ≤20 percent, where the spike value is used in 

place of the Reference Method in the normal RA calculation, as described below. 

(b) Testing Procedures 

(i) Spike the sample to the CEMS with a calibration standard 

containing the pollutant of interest and CO or other non-soluble, 

non-reacting alternative tracer gas (alternative tracer gas) at a flow 

rate not to exceed 10 percent of the CEMS sampling flow rate and 

of such concentrations as to produce an expected 40-80 percent of 

full scale span for the pollutant of interest and a quantifiable 

concentration of CO (or alternative tracer gas) that is at least a 

factor of 10 higher than expected in the unspiked stack gas. The 

calibration standards for both pollutants of interest and CO (or 

alternative tracer gas) must meet Rule 218.1 requirements. 

(ii) Monitor the CO (or alternative tracer gas) using an appropriate 

continuous (or semi-continuous if necessary) monitor meeting the 

requirements of Method 100.1 and all data falling within the 10-95 

percent full scale span, and preferably within 30-70 percent full 

scale span. 

(iii) Alternate spiked sample gas and unspiked sample gas for a total of 

nine (9) runs of spiked sample gas and ten runs of unspiked sample 

gas. Sampling times should be sufficiently long to mitigate 

Response Time and averaging effects. 

(iv) For each run, the average CEMS reading must be between 40 

percent full scale span and 80 percent full scale span. If not, adjust 
218.1-38 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

spiking as necessary and continue runs, but expected spike must 

represent at least 50 percent of the total pollutant value read by the 

CEMS. 

(v) Calculate the spike recovery for both the pollutant and the CO (or 

alternative tracer gas) for each run by first averaging the pre- and 

postspike values for each run and subtracting that value from the 

spiked value to yield nine (9) values for recovered spikes. 

(vi) Using the CO (or alternative tracer gas) spike recovery values for 

each run and the certified CO (or alternative tracer gas) 

concentration, calculate the dilution ratio for each run. Multiply 

the certified pollutant concentration by the dilution factor for each 

run to determine the expected diluted pollutant concentrations. 

Using the expected diluted concentrations as the “Reference 

Method” value, calculate the Relative Accuracy. The RA shall be 

≤20 percent. 

(4) Low Level Spike Recovery/Bias Factor Determination 

The low-level spike recovery/bias factor determination is used to determine if a 

significant bias exists at concentrations near the 10 percent full scale span level. 

The spiking facility/interface shall be a permanently installed part of the CEMS 

sample acquisition system and accessible to the APCO staff as well as the CEMS 

operator. 

(a) Performance Specifications 

There are no pass/fail criteria with respect to the magnitude of the percent 

Relative Accuracy. There are performance criteria for the range of 

concentration on the CEMS the extent to which the spike must be greater 

than the background pollutant level. 

(b) Testing Procedures 

(i) Spike the sample to the CEMS with a calibration standard 

containing the pollutant of interest and CO or other non-soluble, 

non-reacting alternative tracer gas (alternative tracer gas) at a flow 

rate not to exceed 10 percent of the CEMS sampling flow rate and 

of such concentrations as to produce an expected 10-25 percent of 

full scale span for the pollutant of interest and a quantifiable 

concentration of CO (or alternative tracer gas) that is at least a 

factor of 10 higher than expected in the unspiked stack gas. The 

calibration standards for both pollutants of interest and CO (or 

alternative tracer gas) must meet Rule 218.1 requirements. 

(ii) Monitor the CO (or alternative tracer gas) using an appropriate 

continuous (or semi-continuous if necessary) monitor meeting the 
AVAQMD RULE 218.1 218.1-39

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

requirements of Method 100.1 and all data falling within the 10-95 

percent full scale span, and preferably within 30-70 percent full 

scale span. 

(iii) Alternate spiked sample gas and unspiked sample gas for a total of 

nine (9) runs of spiked sample gas and ten runs of unspiked sample 

gas. Sampling times should be sufficiently long to mitigate 

Response Time and averaging effects. 

(iv) For each run, the average CEMS reading must be below 25 percent 

full scale span and >10 percent full scale span. If not, adjust 

spiking as necessary and continue runs; but expected spike must 

represent at least 50 percent of the total pollutant value read by the 

CEMS. 

(v) Calculate the spike recovery for both the pollutant and the CO (or 

alternative tracer gas) for each run by first averaging the pre- and 

post-spike values for each run and subtracting that value from the 

spiked value to yield nine (9) values for recovered spikes. 

(vi) Using the CO (or alternative tracer gas) spike recovery values for 

each run and the certified CO (or alternative tracer gas) 

concentration, calculate the dilution ratio for each run. Multiply 

the certified pollutant concentration by the dilution factor for each 

run to determine the expected diluted pollutant concentrations. 

Using the expected diluted concentrations as the “Reference 

Method” value, calculate the Relative Accuracy as specified in 

Rule 218.1. If the average difference is less than the Confidence 

Coefficient then no low level bias factor is applied. If the average 

difference is greater than the Confidence Coefficient and the 

average expected spike is less than the average CEMS measured 

spike, then no low level bias factor is applied. If the average 

difference is greater than the Confidence Coefficient and the 

average expected spike is greater than the average CEMS measured 

spike, then a low level bias factor equal to the absolute value of the 

average difference is added to data reported at or below the 10 

percent of full scale span. 

(5) Low Level RATA/Bias Factor Determination using Enhanced Reference Method 

6.1 

A low level RATA/bias factor determination is designed to determine if there 

exists a statistically significant bias at low level concentrations. It consists of nine 

(9) test runs that measure the stack concentration and the CEMS concentration 

concurrently. 

(a) Performance Specifications 
218.1-40 AVAQMD RULE 218.1 

Continuous Emission Monitoring Performance Specifications 

D1: 02/02/12 

There are no pass/fail criteria with respect to the magnitude of the percent 

Relative Accuracy. There are performance criteria for the special RATA 

with respect to the Reference Method and range of concentration on the 

CEMS. 

(b) Testing Procedures 

The Reference Method for the low level RATA/bias factor determination 

is SCAQMD Method 100.1 

(i) Perform a minimum of nine (9) runs of low level RATA for CEMS 

versus the Reference Method at actual levels (unspiked). 

(ii) The full scale span range for the Reference Method shall be such 

that all data falls with 20 - 95 percent of full scale span range. 

(iii) The Reference Method shall meet all Method 100.1 performance 

criteria. 

(iv) Calculate the average difference (d = CEMS - Reference Method, 

ppm) and Confidence Coefficient (cc = statistical calculated, ppm). 

(v) If d > 0 then the bias = 0 ppm; if d < 0 and |d| > cc then bias = d; if 

d <0 and |d| < cc then bias = 0 ppm. 

(C) Testing Frequency 

For each CEMS, perform the aforementioned performance requirements once a year 

thereafter. These annual assessments shall be completed within six (6) months of the end 

of the calendar quarter in which the CEMS was originally certified. 
AVAQMD Rule 218 and 218.1 B-1

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

APPENDIX "B" 

PUBLIC NOTICE DOCUMENTS

1. Proof of Publication for Notice of Public Hearing – Antelope Valley Press, April 2, 2012 
B-2 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

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AVAQMD Rule 218 and 218.1 

B-3

Continuous Emission Monitoring 

Final Staff Report: 08/24/12
B-4 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

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AVAQMD Rule 218 and 218.1 C-1

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

APPENDIX "C" 

PUBLIC COMMENTS AND RESPONSES

1. USEPA Comment Letter, October 17, 2011 

2. ARB Staff Rule Results, April 23, 2012 

3. Transmittal of EPA Rule Review Comments, April 25, 2012 
C-2 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

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AVAQMD Rule 218 and 218.1 C-3

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

Comment Letter 1 
C-4 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

1 
AVAQMD Rule 218 and 218.1 C-5

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

District Response to Comment Letter 1 

1. The AVAQMD is amending Rule 218 and adopting new Rule 218.1 in response to USEPA’s 

comment. These rules are based on the recommended approved SCAQMD rule versions, in standard 

AVAQMD format. The AVAQMD is proposing to divide the administrative and technical provisions 

of current Rule 218 into two separate rules: Rule 218 – Continuous Emissions Monitoring, and new 

Rule 218.1 – Continuous Emission Monitoring Performance Specifications. Amended Rule 218 

specifies the administrative requirements for continuous emission monitoring including applicability, 

the application and approval process for continuous emission monitoring systems (CEMS), compliance 

dates, and record retention and reporting. Proposed new Rule 218.1 provides for CEMS certifications, 

performance specifications, and technical requirements for CEMS operation and maintenance. 
C-6 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

Comment Letter 2 
AVAQMD Rule 218 and 218.1 C-7

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

District response to comment letter 2 

No comment required. 
C-8 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

Comment Letter 3 

1a 

1b 
AVAQMD Rule 218 and 218.1 C-9

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

3b 

3c 

3d 

3e 

3f 

3a 

2c 

2b 

2a 
C-10 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

District responses to Comment Letter 3 

Rule 218 Comments 

1a. Section (II) and Section (VI)(E)(1) of the Staff Report have been updated to reflect the SIP 

approval at 73 FR 51226 on September 2, 2008. 

1b. Lockheed has indicated that they are compliant with the provisions of the rule and the additional 

time provisions are not necessary. These sections have been removed and cross references have been 

corrected. Specifically, Rule 218 §(E)(1)(d) and §(E)(1)(e) have been removed and cross reference in 

218.1 (C) has been updated to reflect the removal of these sections. 

2a, b, c These sections have been removed in response to previous comment. 

3a. Typographical error has been corrected. 

3b. Typographical error Has been corrected. 

3c. ASTM Method D 4294 or D 2622 82 have been separated to include both test method titles and 

the most current version of each. 

3d. “SCAQMD” has been added to Test Method 100.1 in Rule 218.1 Attachment A §(B)(3)(b)(ii). 

3e. “SCAQMD” has been added to Test Method 100.1 in Rule 218.1 Attachment A §(B)(4)(b)(ii). 

3f. “SCAQMD” has been added to Test Method 100.1 in Rule 218.1 Attachment A §(B)(5)(b)(iii). 
AVAQMD Rule 218 and 218.1 D-1

Continuous Emission Monitoring 

Final Staff Report: 08/24/12 

APPENDIX "D" 

CALIFORNIA ENVIRONMENTAL QUALITY ACT 

DOCUMENTATION

1. Notice of Exemption – Los Angeles County, filed 07/23/12 
D-2 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

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AVAQMD Rule 218 and 218.1 

D-3

Continuous Emission Monitoring 

Final Staff Report: 08/24/12 
D-4 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12
AVAQMD Rule 218 and 218.1 E-1

Continuous Emission Monitoring 

Final Staff Report: 08/24/12 

APPENDIX "E" 

BIBLIOGRAPHY

The following documents were consulted in the preparation of this staff report and the proposed 

amendment of Rule 218 and the adoption of Rule 218.1: 

1. SCAQMD Rule 218 – Continuous Emission Monitoring, Amended May 14, 1999 

2. USEPA Region IX TSD for EPA’s Direct Final Rulemaking for the CA SIP SCAQMD Rule 

218, Continuous Emission Monitoring, March 18, 2010

3. SCAQMD Rule 218.1 – Continuous Emission Monitoring Performance Specifications, 

Adopted May 14, 1999 

4. USEPA Region IX TSD for EPA’s Direct Final Rulemaking for the CA SIP SCAQMD Rule 

218.1, Continuous Emission Monitoring Performance Specifications, March 18, 2010 

5. 47 FR 29231, July 6, 1982 (SCAQMD Rule 218 SIP approval, AVAQMD SIP version) 

6. SCAQMD Chapter X Non-Standard Methods and Techniques, Office of Operations 

Technical Services Division, March 1989 

7. 40 CFR Appendix B to Part 60 – Performance Specifications 

8. 40 CFR Appendix F to Part 60 – Quality Assurance Procedures 

9. SCAQMD Board Meeting Agenda Item 35, May 14, 1999, Attachments and Appendices 

included 
E-2 AVAQMD Rule 218 and 218.1 

Continuous Emission Monitoring 

Final Staff Report: 08/24/12

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