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

(Amended April 6,1979)(Amended August 7,198 l)(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 sub-system 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 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 21 8; that has met the 

applicable performance specifications according to Rule 218(c)(l)(B), and, has 
Rule 218 (Cont.) (Amended May 14,1999) 

received written approval and conditions thereto applying, from the Executive 

Officer. 

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/R97/12 1, September 1997 Revision 

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

incorporates by reference EPA Protocol. 

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. 

CONTINUOUS MONITORING - monitoring in which a minimum of one 

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

each minute. 

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 terns 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. 

DILUENT G.4S - a gas present in a calibration gas mixture or in the source 

emissions which is present in quantities significantly larger than the air 

contaminant. 

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. 

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. 

QUALITY ASSURANCE/QUALITY CONTROL (QNQC) PLAN - a written 

document in which the specific procedures for the operation, calibration and 
Rule 218 (Cont.) (Amended May 14,1999) 

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 21 8 and 21 8.1. 

(1 3) 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. 

(1 5) 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 (1 5) minutes. 

(16) SEMI-CONTINUOUS EMISSION MONITORING SYSTEM (SCEMS) - the 

total combined equipment and systems to semi-continuously determine air 

contaminant and diluent gas concentrations andfor 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. 

(17) SYSTEM FAILURE - inability of the CEMS to meet the requirements of Rule 

2 18.1, "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. 

(1 9) 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. 
Rule 218 (Cont.) (Amended May 14,1999) 

(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 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 calculat air contaminant emission rates or concentrations, as 

specified in Rule 21 8, Sections (e) and (f). 

(c) Requirements for IVew 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 
Rule 218 (Cont.) (Amended May 14,1999) 

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)(l)(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 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)(l)(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)(l)(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)(l)(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 2 18.1, "Continuous Emission Monitoring 

Performance Specifications", Section (b), and the subsequent 

operation and maintenance of the certified CEMS shall be in 
Rule 218 (Cont.) (Amended May 14,1999) 

accordance with the provisions of Rule 218, Sections (b), (e), (f) 

and (g) and of the requirements of Rule 2 18.1 (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)(l)(B)(ii), any 

alternative test methods for 40CFR60, Appendices B and F shall be 

those that are listed in Rule 2 1 8.1, 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 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)(l), 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, sudject 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; 
Rule 218 (Cont.) (Amended May 14,1999) 

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

measurement (concentration, mass emission rate andlor flow rate, 

as applicable) every 15 minutes allowing as equally spaced data 

points as practical; 

(iii) The owner or operator shall include in the QNQC 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 verifj the calculated exeedance; 

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

specifications of Rule 2 1 8.1, Section (e); 

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

provided in Rule 218, Section (c)(l) 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 AssuranceIQuality 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)(l)(B)(i), shall submit to 

the Executive Officer for approval a CEMS QNQC 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 21 8, Section (c)(l)(B)(i), may choose to 

develop alternative CEMS operational test requirements to be included in 

the CEMS QNQC procedures that assure data of equivalent or better 

quality. These alternative QNQC procedures shall be submitted with the 

facility QNQC Plan and are subject to the approval of the Executive 

Officer. 

(d) Requirements for Existing CEMS and SCEMS 

(1) Requirements for Existing CEMS 
Rule 218 (Cont.) (Amended May 14,1999) 

(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 2 18.1, Sections 

(c) and (4. 

(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 2 1 8.1, Sections (c) and (d). After final approval, the CEMS shall be 

operated and maintained according to the provisions of Rule 2 18, Sections 

(b), (e), (f) and (g), and the requirements of Rule 2 18.1, Sections (c) and 

(dl. 

(C) Modifications requiring recertification to any existing CEMS shall be 

reviewed and approved according to the conditions under Rule 218 

Section (c)(l)(B)(i) or (ii), as applicable. After final approval, the 

modified CEMS shall be operated and maintained according to the 

conditions under Rule 21 8, Section (c)(l)(B)(i) or (ii), as applicable. 

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

and (B) shall comply with the provisions of Rule 2 1 8.1, Sections 

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

Rule 2 18, Sections (b) and (c), 110 later than May 14,2006. 

(ii) The requirements of Rule 21 8, Section (d)(l)(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 

(11) Calibration Error 

(111) 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 subsection every three years after May 14, 2006. This sub-section 
Rule 218 (Cont.) (Amended May 14,1999) 

shall not apply to existing CEMS that are required to comply with 

the provisions of Rule 21 8.1, Sections (b) and (d), or, 40 CFR60, 

Appendices B and F, as applicable, and Rule 21 8, 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 Assurance1 Quality Control (QAIQC) Plan no later than 

May 14, 2000. The written QNQC 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 

2 18, Section (c), or, 

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

fee(s) as specified in Rule 30 1, or, 

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

- (d)(l)(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 2 18.1, Sections 

(4 and (dl. 

(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 2 18.1, Sections (c) and (d). After final approval, the SCEMS shall be 

operated and maintained according to the provisions of Rule 2 18, Sections 

(b), (e), (f) and (g), and the requirements of Rule 21 8.1, Sections (c) and 

(4- 

(C) Modifications requiring recertification to any existing SCEMS shall be 

reviewed and approved according to the conditions under Rule 218 

Section (c)(l)(B)(i) or (ii), as applicable. After final approval, the 

modified CEMS shall be operated and maintained according to the 

conditions under Rule 2 18, Section (c)(l)(B)(i) or (ii), as applicable. 
Rule 218 (Cont.) (Amended May 14,1999) 

(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 2 18.1 

Section (e) - "Time Sharing Requirements" and with the provisions of 

Rule 218.1 Sections (b) 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 21 8, Section (c)(l)(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 andlor 

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

additional information specified by the Executive Officer, to evaluate the accuracy 
Rule 218 (Cont.) (Amended May 14,1999) 

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

six months to 'the Executive Officer, except when more frequent reporting is 

specifically required by another District rule, or the Executive Officer, on a caseby-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 andor 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 andor 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 2 18, 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 established procedure in District Rule 518.2 - Federal 

Alternative Operating Condition. 
Rule 218 (Cont.) (Amended May 14,1999) 

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

required under Rule 2 18, 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. 

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.