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(Adopted January 9, 1976)(Amended April 1, 1977)(Amended August 5, 1977)

(Amended April 6, 1979)(Amended August 7, 1981)(Amended May 14, 1999)

RULE 218. CONTINUOUS EMISSION MONITORING

(a) Definitions

(1) ANALYZER- the part of the continuous emission monitoring system

(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 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 record 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.

(3) CALIBRATION CHECK - a procedure performed to determine the

CEMS response to a given gaseous compound concentration. A certified 
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calibration gas mixture is injected into the CEMS as close to the probe tip 

as practical.

(4) CERTIFIED CEMS - a CEMS installed, tested, operated, maintained, and 

calibrated according to the applicable requirements of Rule 218; that has

met the applicable performance specifications according to

Rule 218(c)(1)(B), and, has received written approval and conditions

thereto applying, from the Executive Officer.

(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.

(6) 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 major

subsystems: sampling interface, analyzer and data acquisition system. 

(7) CONTINUOUS MONITORING - monitoring in which a minimum of one 

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 which is present in quantities significantly larger than the 

air contaminant.

(10) LABORATORY APPROVAL PROGRAM (LAP) - a program

administered by the District that grants test-method-specific approvals to

independent testing laboratories or firms that perform tests to determine

source compliance with District rules and regulations.
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(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

Executive Officer 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. 

(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.

(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 Executive Officer. 

Repairs to a malfunctioning system are excluded from this definition.

(14) SAMPLING INTERFACE - that part of the CEMS that performs 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.

(15) SEMI-CONTINUOUS EMISSION MONITORING - a monitoring

technique in which a minimum of one 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 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.
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(17) SYSTEM FAILURE - inability of the CEMS to meet the requirements of

Rule 218.1, “Continuous 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".

(18) TIME-SHARING - a monitoring technique where an analyzer and possibly 

the associated sample conditioning system is used on more than one

source.

(19) WORKING DAY - Monday through Friday excluding holidays.

(20) 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.

(21) ZERO GAS - a gas containing less than a specified amount of the air

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.

(b) Applicability and Monitoring Requirements for New, Modified and Existing

CEMS

(1) 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:

(A) This Rule shall not apply to CEMS subject to Regulation XX -

“Regional Clean Air Incentives Market (RECLAIM)”, Regulation

IX - “New Source Performance Standards (NSPS)”, Regulation X -

National Emission Standards for Hazardous Air Pollutants

(NESHAPS), or Regulation XXXI - "Acid Rain Program". 

(B) 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.

(C) This Rule shall not apply to CEMS where alternative performance

specifications are required by another District rule.

(2) The owner or operator of any equipment subject to this Rule shall provide, 

properly install, operate, and maintain in calibration and good working

order a certified CEMS to measure the concentration and/or emission 
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rates, as applicable, of air contaminants and diluent gases, flow rates, and

other required parameters. The owner or operator shall also provide the

necessary records and other data necessary to calculate air contaminant

emission rates or concentrations, as specified in Rule 218, Sections (e) and 

(f).

(c) Requirements for New and Modified CEMS and SCEMS

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

(A) The owner or operator of any equipment subject to this Rule shall

submit to the Executive Officer an “Application for CEMS” or

“Application for CEMS Modification”, as applicable. Any

application submitted on or after May 14, 1999, shall require an

initial approval by the Executive Officer prior to installation of a new 

CEMS or modification of an existing CEMS. The Executive Officer 

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 Executive Officer 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 Executive Officer 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 (c)(1)(B). 

The owner or operator shall notify the Executive Officer in writing

at least 14 days before the scheduled certification test dates. The

certification tests shall be performed by a testing laboratory
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approved under the District Laboratory Approval Program. Data

from such tests shall be submitted to the Executive Officer 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 (c)(1)(B). 

After final approval, modifications made to the CEMS shall be

reviewed and approved by the Executive Officer according to the

specifications stipulated in Rule 218, Section (c)(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 (c)(1)(A),

the applicant shall indicate either one of the following conditions:

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

the provisions of Rule 218.1, “Continuous Emission

Monitoring Performance Specifications”, Section (b), and

the subsequent operation and maintenance of the certified

CEMS shall be in accordance with the provisions of Rule

218, Sections (b), (e), (f) and (g) and of the requirements of 

Rule 218.1(b) and (d), 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" (40CFR60),

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 (b), (e), (f) and (g), and the requirements 

of 40CFR60, Appendix F - "Quality Assurance Procedures"

(Appendix F).

Notwithstanding the requirements of Section (c)(1)(B)(ii),

any alternative test methods for 40CFR60, 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-
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lieu of the "Application for CEMS Modification" when the

modification has been made in accordance with the written

technical guidance document approved by the Executive Officer.

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

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

Section (c)(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 Executive Officer, that no

CEMS technology is commercially available for the applicable

contaminant and the applicable limits.

(B) If the conditions in Rule 218, Section (c)(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 Executive

Officer;

(ii) The SCEMS shall be capable to take and record a minimum 

of one 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 exeedance of the allowable limit or standard is

calculated using fewer than 100% 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 exeedance;

(v) If a time shared SCEMS is proposed, it shall meet the

performance specifications of Rule 218.1, Section (e);
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(C) The requirements for the application submittal and approval of

CEMS as provided in Rule 218, Section (c)(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) Quality Assurance/Quality Control 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

(c)(1)(B)(i), shall submit to the Executive Officer 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

(c)(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 Executive Officer.

(d) Requirements for Existing CEMS and SCEMS

(1) Requirements for Existing CEMS

(A) A CEMS installed and granted final approval before May 14, 1999 

shall be maintained and operated according to the provisions of

Rule 218, Sections (b), (e), (f) and (g), and the requirements of

Rule 218.1, Sections (c) and (d). 

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

Executive Officer before May 14, 1999 shall be reviewed and

approved by the Executive Officer according to the specifications

and requirements of Rule 218.1, Sections (c) and (d). After final

approval, the CEMS shall be operated and maintained according to 

the provisions of Rule 218, Sections (b), (e), (f) and (g), and the

requirements of Rule 218.1, Sections (c) and (d).
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(C) Modifications requiring recertification to any existing CEMS shall

be reviewed and approved according to the conditions under Rule

218 Section (c)(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 (c)(1)(B)(i) or (ii), as

applicable.

(D) (i) All existing CEMS as prescribed in Rule 218, Sections

(d)(1)(A) and (B) shall comply with the provisions of Rule

218.1, Sections (b) and (d), or 40CFR60 Appendices B and 

F, as applicable, and of Rule 218, Sections (b) and (c), no

later than May 14, 2006.

(ii) The requirements of Rule 218, Section (d)(1)(D)(i) shall be 

waived for a period of three years if the owner or operator 

demonstrates, to the satisfaction of the Executive Officer, 

that the existing CEMS is providing data that are 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

(VIII) Excursions beyond quality control limits in QA plan.

The owner or operator may apply for a waiver under this

sub-section every three years after May 14, 2006. This subsection shall not apply to existing CEMS that are required

to comply with the provisions of Rule 218.1, Sections (b)

and (d), or, 40 CFR60, Appendices B and F, as applicable, 

and Rule 218, Sections (b) and (c), as a result of CEMS

modifications requiring recertification, rule implementation,

or, compliance with a permit condition.

(E) The owner or operator of existing CEMS shall develop and

implement a written Quality Assurance/ Quality Control (QA/QC)
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Plan no later than May 14, 2000. The written QA/QC Plan shall be 

kept on record and available for inspection upon request by the

Executive Officer. 

(F) On or before May 14, 2005, the owner or operator of any existing 

CEMS shall submit to the Executive Officer for approval: 

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

facility that the existing CEMS meets the requirements of

Rule 218, Section (c), or,

(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

(d)(1)(D)(i), with documentation supporting the required

demonstration;

(2) Requirements for Existing SCEMS

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

shall be maintained and operated according to the provisions of

Rule 218, Sections (b), (e), (f) and (g), and the requirements of

Rule 218.1, Sections (c) and (d). 

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

Executive Officer before May 14, 1999 shall be reviewed and

approved by the Executive Officer according to the specifications

and requirements of Rule 218.1, Sections (c) and (d). After final

approval, the SCEMS shall be operated and maintained according

to the provisions of Rule 218, Sections (b), (e), (f) and (g), and the 

requirements of Rule 218.1, Sections (c) and (d).

(C) Modifications requiring recertification to any existing SCEMS shall

be reviewed and approved according to the conditions under Rule

218 Section (c)(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 (c)(1)(B)(i) or (ii), as

applicable.

(D) The owner or operator of an existing SCEMS operating on or

before May 14, 1999 shall be required to comply with the

provisions of Rule 218.1 Section (e) - “Time Sharing

Requirements” and with the provisions of Rule 218.1 Sections (b)
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218 - 11

and (d), or, 40CFR60 Appendix B and F, as applicable, when the

equipment served by the time-shared 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 (c)(1)(B)(i) or (ii), 

as applicable. 

(e) 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 Executive Officer. Records shall be maintained by the CEMS owner or 

operator for a minimum period of two years, unless otherwise specifically

provided by another District regulation or permit conditions, and, shall be

made available to the Executive Officer 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 two years unless otherwise

specifically provided by another District regulation or permit conditions,

and shall be made available to the Executive Officer upon request.

(f) 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 Executive Officer, to

evaluate the accuracy and precision of the measurements. The summary

shall be submitted once every six months to the Executive Officer, except 
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when more frequent reporting is specifically required by another District

rule, or the Executive Officer, 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-month period being reported, in the form and 

manner prescribed by the Executive Officer. The summary shall be

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

available to the Executive Officer 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 Executive Officer. 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 Executive Officer

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.

(B) In the case of a CEMS failure or shutdown, compliance with the

provisions of Rule 218, Section (b) 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 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
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established procedure in District Rule 518.2 - Federal Alternative

Operating Condition.

(C) Regularly scheduled CEMS maintenance shall be deferred until the

report required under Rule 218, Section (f)(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.

(g) Posting of Written Approval for New, Modified and Existing CEMS and SCEMS

The CEMS owner or operator of an approved CEMS shall affix 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, legible, and safely accessible. In the event that the equipment is

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 Executive Officer.