UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX AIR DIVISION

Technical Support Document 

For

EPA's Direct Final Rulemaking

for the

California State Implementation Plan

South Coast Air Quality Management District, 

Rule 218, Continuous Emission Monitoring

Prepared by: Stanley Tong

 March 18, 2010
2

RULE IDENTIFICATION

Agency: South Coast Air Quality Management District (SCAQMD)

SIP Approved Rule: Rule 218 – Stack Monitoring

Amended – August 7, 1981; 

Submitted – October 23, 1981

EPA Approved – July 6, 1982 (47 FR 29231)

Subject of this TSD: Rule 218 – Continuous Emission Monitoring 

Amended - May 14, 1999; 

Submitted July 23, 1999

RULE SUMMARY - Rule 218 establishes requirements for continuous stack emission 

monitors of oxides of nitrogen (NOx), sulfur dioxide (SO2), gaseous sulfur 

compounds, and carbon monoxide (CO). The South Coast Air Quality Management 

District (SCAQMD) staff report for this rule summarizes that many of the provisions 

of the 1981 version of Rule 218 have become out-of-date since the adoption of the 

Regional Clean Air Initiative Market (RECLAIM) program and the advancement in 

continuous emission monitoring technology. SCAQMD staff recognized the 

deficiency of several provisions in Rule 218 and took steps to amend the rule to 

better define specifications and guidelines for continuous emission monitoring 

systems (CEMS) to eliminate ambiguity in both the administrative and technical 

provisions of the rule. SCAQMD also took the requirements from the original SIP 

approved rule and separated them into an administrative portion and a technical 

portion. Rule 218 now covers administrative requirements for CEMS and includes

applicability, application and approval process, and recordkeeping and reporting 

requirements for CEMS. The technical requirements for CEMS in the 1981 version 

of Rue 218 were updated moved to Rule 218.1.

Changes from the approved SIP rule include:

1. Changed the title of Rule 218 from "Stack Monitoring" to "Continuous Emission 

Monitoring".

2. Revised the applicability of the rule to cover all sources that require CEMS as 

required by a SCAQMD regulation or permit condition except CEMS under 

RECLAIM, New Source Performance Standards (NSPS), and Acid Rain. Rule 

218 also does not apply to CEMS subject to permit conditions whose purpose is 

to monitor the performance of basic control equipment rather than to meet limits 

or standards.

3. Added CEMS application, modification, and certification procedures.

4. Provided an option between 40 CFR 60 Appendices B and F and Rule 218.1 for 

CEMS certification and quality assurance.
3

5. Allowed the use of semi-continuous emission monitoring systems (SCEMS) in 

lieu of CEMS.

6. Required owners or operators of existing CEMS to submit either 

a) a certification that existing CEMS meets the requirements for a new or 

modified CEMS, or

b) an application for new or modified CEMS, or

c) an application for waiver

7. Required existing CEMS to meet the standards for new or modified CEMS by 

May 14, 2006.

8. Required existing CEMS and SCEMS be subject to standards for a new or 

modified CEMS when a modification is made that requires recertification.

9. Required existing time-shared SCEMS be subject to standards for a new or 

modified CEMS when a modification is made that requires their recertification.

10. Added recordkeeping provision for calculations and raw parameter data used for 

calculations and emissions rates.

11. Revised submission of CEMS data from once a month to once every three 

months. 

12. Required reporting exceedances and failure or shutdown within 24 hours, or by 

the next business day.

13. Updated several definitions.

EPA EVALUATION - The following documents were used to evaluate the submitted 

rule. 

1. 40 CFR 60 Appendix B – Performance Specifications

2. 40 CFR 60 Appendix F – Quality Assurance Procedures

3. Enforceability - The Bluebook (Issues Relating to VOC Regulation Cutpoints, 

Deficiencies, and Deviations, EPA, May 25, 1988) and the Little Bluebook 

(Guidance Document for Correcting Common VOC & Other Rule Deficiencies,

EPA Region 9, August 21, 2001) were used to help evaluate compliance with the 

CAA §110(a)(2)(A) requirement for enforceability. 

4. SIP Relaxation - Where previous versions of rules have been SIP approved, new 

submittals must comply with CAA §110(l) and §193 regarding SIP relaxations.
4

Changes to Rule 218 include defining "continuous monitoring" as a minimum of one 

measurement taken and recorded each minute and averaged over 15 minutes or 60 

minutes. Semi-continuous emission monitoring systems (SCEMS) are allowed a 

minimum of one measurement taken and recorded every 15 minutes. Measurements 

may be concentration, mass emission rate, stack gas flow rate and/or fuel flow rate. The 

standards for CEMS also apply to SCEMS.

The rule also requires certification that existing CEMS meet the new standard and for 

facilities to develop and implement a quality assurance/quality control plan. If the owner 

or operator of the CEMS elects the performance specifications of Rule 218.1, then they 

will be required to submit a QA/QC plan within 90 days after CEMS installation or 

modification.

CEMS owners or operators are required to submit a CEMS quarterly report within 30 

days of the end of each three month period.

EPA reviewed the draft amendments and provided a recommendation that facilities 

choosing to continue to operate under the existing CEMS option should be required to 

develop a QA/QC plan and that the QA/QC plan should be implemented within a year of 

adopting amendments to Rule 218 and that records be maintained for five years instead 

of the minimum two years. Rule 218 was amended to require the QA/QC plan but did 

not extend the recordkeeping requirement to five years.

ADDITIONAL RECOMMENDATION FOR THE NEXT RULE REVISION - The following 

is recommended for the next time the rule is amended.

1. Consistent with CAA Title V and the federal statute of limitations, we recommend 

that Section e(1) require that records be maintained for five instead of two years.

EPA ACTION –

The submitted Rule 218 strengthens the SIP. There are no expected emission 

reductions from this rule as it primarily updates administrative requirements for 

continuous emission monitoring systems. The rule largely fulfills the relevant CAA §110 

and part D requirements. EPA staff recommends approval of Rule 218 pursuant to 

CAA §110(k)(3) and §301(a).

ATTACHMENTS –

1. SCAQMD Rule 218, Continuous Emission Monitoring, as submitted on July 23, 

1999.

2. SCAQMD Rule 218, Stack Monitoring, as approved into the SIP on July 6, 1982. 
5

3. Comment letter dated March 31, 1999, Review of Proposed Amended Rule 218 

and Proposed Rule 218.1, from EPA Region IX (Andrew Steckel) to SCAQMD 

(Elaine Chang).

REFERENCES -

1. "Issues Relating to VOC Regulation Cutpoints, Deficiencies, and Deviations,"

(a.k.a., Bluebook) EPA OAQPS, May 25, 1988.

2. "Guidance Document for Correcting Common VOC & Other Rule Deficiencies," 

(a.k.a., Little Bluebook), EPA Region 9, August 21, 2001 

(http://www.epa.gov/region09/air/sips/littlebluebook2001.pdf).

3. Comment letter dated March 31, 1999, Review of Proposed Amended Rule 218 

(PAR 218 – December 11, 1998) and proposed Rule 218.1 (PR 218.1 – no date)

from EPA Region IX (Andrew Steckel) to SCAQMD (Elaine Chang).