UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX AIR DIVISION

Technical Support Document

F or

EPA ' s Direct Final Rulemaking

for the

California State Implementation Plan

South Coast Air Quality Management District,

Rule 218 .1 Continu ous Emission Monitoring Performance Specifications

Prepared by: Stanley Tong

March 18

, 20102

RULE IDENTIFICATIO N

Agency: South Coast Air Quality Management District (SCAQMD)

SIP Approved Rule: There is no prior versi on of this rule in the SIP

Subject of this TSD: Rule 218 .1

- Continuous Emission Monitoring Performance

Specifications

A dopted May 14, 1999;

Submitted July 23, 1999

RULE SUMMARY

- R equirements from the 1981 SIP approved version of Rule 218

were updated and divided into an administrative portion (Rule 218) and a technical

portion (Rule 218.1). Rule 218.1 is a new rule and contains requirements for the

certification of continuous emission monitoring systems (CEMS)

, the performance

specifications of CEMS , and the operation and maintenance of CEMS

.

The rule requirements include:

1. Standards for new or modified CEMS

, and semi

- continuous emission monitoring

systems (SCEMS).

2. Standards for existing CEMS and SCEMS.

3. Requirements for time shared SCEMS

4. Requirements prior to certification or relative accuracy testing for CEMS

sampling location, full span range, strip chart recorder, data acquisition system,

and operational period.

5. Certification tests and specifications including calibration error, relat ive accuracy

tests, response times, concentration stratification, cyclonic flow, interference

check, and linearity error.

6. CEMS operational requirements and performance standards after certification

including : daily calibration error, system bias test, and periodic relative accuracy

tests.

7. Standards for calibration and zero gas.

8. Allowed reference methods.3

EPA EVALUATION

- The following documents were used to evaluate the submitted

rule.

1. 40 CFR 60 Appendix B

– Performance Specifications

2. 40 CFR 60 Ap pendix 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 Defici encies,

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.

The submitted rule provides performance specifications standards for new or modified

CEMS, and standards for existing CEMS. S tandards that originally appeared in Rule

218 for existing CEMS were moved to Rule 218.1 and were generally unchanged except

for minor technical clarification s

.

The Standards for new or modified CEMS include specifications and requirements for

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

performance sp ecifications for the operation and maintenance of the CEMS after it has

been certifi ed by the South Coast AQMD.

Daily calibration error tests, quarterly cylinder gas audits, and annual system bias and

relative accuracy test audits are also required for qu ality assurance/quality control under

Rule 218.1.

EPA reviewed a draft version of Rule 218.1 and p rovided the following general c omment

in a March 31, 1999 comment letter :

1. Absolute de

- minimus value for relative accuracy (para (b)(2)(C)(i))

EPA conside rs that a t medium to high emission limits, Rule 218.1's relative accuracy

criteria are equivalent to, or are more stringent than the federal standards. However, at

very low emission limits, (less than 5 ppm NOx), the rule's relative accuracy criteria usin g

de

- minimus values, becomes less stringent than the federal limits

.

EPA further stated in the comment letter that relative accuracy values at very low

concentrations, such as less than 1 ppm may not be meaningful due to the limitations of

current techn ology in 1999 . These limitations include the availability of low

concentration protocol calibration gases, and the degree of precision of the reference

test method at low concentrations.

However, technology has advanced since we made our orig inal comme nt. We

recommend the next time Rule 218.1 is amended that South Coast remove the de4

minimus limits from R ule 218.1 for NOx and CO, since 2 ppm limits are now appearing

in permits

.

The approvability comments we had on the draft rule included cases of Exec utive Office

discretion for : alternative sampling locations, alternative full span ranges, alternative

certification metho ds for low concentration gases, and instrument response time

specifications exceeding standards in 40 CFR 60, Appendix A. Thes e appro vability

issues were corrected prior to adopti on of the rule by the SCAQMD

.

EPA also provided a recommendation that quarterly cylinder gas audits be required.

This recommendation was incorporated into proposed Rule 218.1 prior to adoption.

ADDITIONAL RE COMMENDATION FOR THE NEXT RULE REVISION

- The following

is recommended for the next time the rule is amended.

1. The relative accuracy performance specifications for CEMS in Rule 218.1

(b)(2)(C)(i) allows facilities to meet the greater of either of the f ollowing conditions:

a. Less than or equal to 20 percent of the mean value of the reference method or

b. A de minimus concentration.

Rule 218.1 lists the de minimus concentration for NOx as 1.0 ppm and for CO, it is 4.0

ppm

Equipment and technology hav e advanced since Rule 218.1 was originally adopted in

1999 and equipment is no w being permitted with NOx and CO limits of 2 ppm. EPA

recommends South Coast drop the de minimus concentration option for NOx and CO

and evaluate the applicability of the remai ning de minimus concentrations (SO2,

reduced sulfur compounds) the next time Rule 218.1 is amended.

EPA ACTION

–

The submitted Rule 218.1 strengthens the SIP

. There are no expected emission

reductions from this rule as it primarily updates technical pe rformance specifications for

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

and part D requirements

. EPA staff recommends approval of Rule 218.1 pursuant to

CAA § 110(k)(3) and § 301(a)

.

ATTACHMENT S

–

1. SCAQMD Rule 218.1, Continuous Emission Monitoring Performance

Specifications, as submitted on July 23, 1999.

2. SCAQMD Rule 218, Stack Monitoring, as approved into the SIP on July 6, 1982.5

REFERENCES

-

1. " Issues Relating to VOC Regulation Cutpoints, Deficienci es, 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, Augu st 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 S teckel) to SCAQMD ( Elaine Chang ).