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 1146 and 1146.1

Emissions of Oxides of Nitrogen from Industrial, Institutional, and Commercial 

Boilers, Steam Generators, and Process Heaters

And

Emissions of Oxides of Nitrogen from Small Industrial, Institutional, and 

Commercial Boilers, Steam Generators, and Process Heaters

Prepared by: Nicole Law

Reviewed by: Andrew Steckel

July 2014
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Agency: South Coast Air Quality Management District 

(SCAQMD)

SIP Approved Rules: Rule 1146 - Emissions of Oxides of Nitrogen from 

Industrial, Institutional, and Commercial Boilers, Steam 

Generators and Process Heaters

Amended – November 17, 2000

Submitted – May 8, 2001

EPA Approved – April 8, 2002 (67 FR 16640)

Rule 1146.1 - Emissions of Oxides of Nitrogen from 

Small Industrial, Institutional, and Commercial Boilers, 

Steam Generators, and Process Heaters

Amended – May 13, 1994

Submitted – July 13, 1994

EPA Approved – September 6, 1995 (60 FR 46220)

Superseded Submittals: Rule 1146

Amended - September 5, 2008

Submitted – July 20, 2010

Rule 1146.1

Amended – September 5, 2008

Submitted – July 20, 2010

Subjects of this TSD: Rule 1146

Amended – November 1, 2013

Submitted – May 13, 2014

Rule 1146.1

Amended – November 1, 2013

Submitted – May 13, 2014

BACKGROUND – EPA previously proposed a limited approval and limited 

disapproval of both SCAQMD Rules 1146 and 1146.1 as submitted on July 20, 

2010. The basis for our proposed limited disapproval was inconsistency with 

Clean Air Act (CAA) requirements for enforceability and the national credible 

evidence rule from 1997 (62 FR 8314). The proposed rulemaking was never 

finalized, therefore the current rule revisions in the SIP are those approved on 

April 8, 2002 and September 6, 1995. SCAQMD has since revised its rules to 

address the deficiencies identified in our proposed limited approval/disapproval 

and submitted them to EPA on May 13, 2014. This TSD addresses the rules as 

submitted on May 13, 2014.

RULE SUMMARY -
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Rules 1146 and 1146.1 were amended to strengthen the NOx emission limits,

update compliance determination, and address EPA’s enforceability deficiencies. 

A Compliance Schedule section was also added to Rule 1146 and updated in 

Rule 1146.1. Rules 1146 and 1146.1 do not apply to RECLAIM facilities. 

Changes from the approved SIP rules include:

For Rule 1146:

1. Added several definitions in Section (b) and made numerous other editorial 

changes to improve clarity. 

2. Revised the requirements in Section (c) to add tables for Standard 

Compliance Limits and Schedule and Enhanced Compliance Limits and 

Schedule. Both tables introduce lower NOx emission limits as well as 

compliance deadlines. 

3. Added a formula in Section (c) to address how a weighted limit is 

calculated for dual fuel co-fired combustion units, added requirements for

maintaining records on tune-ups, and added requirements for the owners 

and operators of Group II or III units to submit a compliance plan.

4. Revised the compliance determination Section (d) to limit source testing 

after tuning or servicing of units, clarify approved test methods, add testing 

frequency, and allow portable analyzers for diagnostic emissions checks.

This section was also revised to address EPA’s enforceability deficiencies.

5. Added a Section (e) Compliance Schedule to specify when operators and 

owners need to comply with specific rule provisions.

For Rule 1146.1:

1. Added several definitions in Section (b) and made numerous other editorial 

changes to improve clarity.

2. Revised the requirements in Section (c) to add an emissions limit table with 

lower NOx emission limits and compliance dates.

3. Added a formula in Section (c) to address how a weighted limit is 

calculated for dual fuel co-fired combustion units. This section also added 

a CO limit for natural gas fired units and requirements for maintaining

records of tune-ups.

4. Revised the compliance determination Section (d) to limit source testing 

after tuning or servicing of units, clarifying approved test methods, add 
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frequency of testing, and allow portably analyzers for diagnostic emissions. 

This section was also revised to address EPA’s enforceability deficiencies. 

5. Revised Section (e) Compliance Schedule to update the applicable 

compliance dates.

EVALUATION CRITERIA - The following criteria were used to evaluate the 

submitted rules. 

1. 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. 

2. Stringency - EPA’s Alternative Control Techniques Document (ACT) titled, 

“NOx Emissions from Industrial/Commercial/Institutional (ICI) Boilers” (EPA453/R-94-022, March 1994), CARB’s RACT/BARCT guidance titled, 

“Determination of Reasonably Available Control Technology and Best 

Available Retrofit Control Technology for Industrial, Institutional, and 

Commercial Boilers, Steam Generators, and Process Heaters” (July 18, 

1991), and other state and local rules for this category were used to help 

evaluate the RACT requirements of CAA §182(b)(2) and §182(f). 

3. SIP Relaxation - CAA §110(l) prohibits EPA from approving any SIP revision 

that would interfere with any applicable requirement concerning attainment 

and reasonable further progress (RFP) or any other applicable requirement 

of the CAA. In addition, CAA §193 prohibits the modification of any SIPapproved control requirement in effect before November 15, 1990, in a 

nonattainment area.

EPA EVALUATION - A summary of our evaluation of the three criteria follows.

1. The rule requirements and applicability are clear, and the testing, 

recordkeeping, reporting and other provisions sufficiently ensure that 

affected sources and regulators can evaluate and determine compliance 

with Rules 1146 and 1146.1 consistently. 

2. The submitted rules are more stringent than CARB’s RACT/BARCT 

guidance and other California District rules for this category, including San 

Joaquin Valley Unified Air Pollution Control District (SJVUAPCD) Rules

4306 and 4307 and Sacramento Metropolitan Air Quality Management 

District (SMAQMD) Rule 411. The rule requirements are also comparable 

to those described in EPA’s 1994 ACT. As a result, we have determined 

that this rule is as stringent as other California District rules for this category. 
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3. We propose to determine that our approval of the submittal would comply 

with CAA §§110(l) and 193 because (1) the proposed SIP revision would 

not interfere with the on-going process for ensuring that requirements for 

RFP and attainment of the NAAQS are met, and (2) the emission limits in 

the submitted rule are more stringent than the existing SIP-approved control 

requirements that they would replace.

Additional discussion of specific issues follows.

1. RACT discussion - The submitted rules 1146 and 1146.1 are only applicable 

to sources that are not subject to RECLAIM, as is described in the 

applicability section of the rules and Table 1 in SCAQMD Rule 2001. 

RECLAIM covers all major NOx sources, therefore rules 1146 and 1146.1 

are not required to fulfill RACT requirements. However, even if RACT were 

required, we believe these two SCAQMD rules would likely implement 

RACT for NOx emissions. The emission limits are comparable to emission 

limits in SJVUAPCD Rules 4306 and 4307 and SMAQMD Rule 411. 

Additionally, the submitted rules are as stringent as CARB’s RACT/BARCT 

guidance and there is no CTG for this category.

2. RACM discussion - CAA §172(c)(1) requires implementation of all 

reasonable available control measures (RACM) for Ozone and PM2.5 as 

expeditiously as practicable in SCAQMD. As described above, we believe 

that the NOx emission limits in the submitted rules implement RACT for 

NOx. As a result, we believe that this demonstration is sufficient to 

determine that the rule requires all measures that are “reasonably available” 

within the meaning of RACM under CAA §172(c)(1). In separate 

rulemakings, EPA will take action on the State’s RACM demonstration for 

PM2.5 and Ozone based on evaluation of the control measures submitted 

as a whole and their overall potential to advance the applicable attainment 

dates in the South Coast area.

3. Enforceability discussion - The previously submitted amendments of rules 

1146 and 1146.1 were not finalized into the SIP due to rule deficiencies 

regarding enforceability and the national credible evidence rule from 1997. 

The rules precluded the use of both source test data and portable 

analyzers test results from being used to prove a violation of the emission 

standards in the compliance determination sections (d) in both rules. The 

rules now clarify that emission checks of NOx emissions, CO, and oxygen 

analyzers done by the operator or owner are used as a diagnostic tool for 

monitoring purposes, while diagnostic emission checks conducted by 

District staff will be used to determine rule violations. Additionally, the 

language stating that source tests shall not constitute a violation has been 

removed. We agree that the District has addressed the enforceability and 

credible evidence concerns in these new rule amendments.
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RULE DEFICIENCIES - We have identified no deficiencies with Rules 1146 and 

1146.1 sufficient for EPA to propose less than full approval.

ADDITIONAL RECOMMENDATIONS FOR THE NEXT RULE REVISION - The 

following revisions are not currently the basis for rule disapproval, but are 

recommended for the next time the rule is amended. 

1. To improve clarity and enforceability of section (d)(2) in rules 1146 and 

1146.1, consider defining the terms “as-found operating condition,” 

“unscheduled repair,” “start-up,” and “shutdown.” As they pertain to this 

rule. These definitions should be consistent with EPA Excess Emission 

Guidance (September 20, 1999), where appropriate. Please also consider 

adding recordkeeping requirements to this provision to demonstrate 

unscheduled repairs and operating hours.

EPA ACTION - The submitted Rules 1146 and 1146.1 strengthen the SIP by 

lowering NOx emission limits and clarifying rule provisions. The 2008 final staff 

report for Rule 1146 projected the rule would reduce NOx emissions by 

approximately 1.2 tons per day beginning in 2015 and the 2008 final staff report 

for Rule 1146.1 projected the rule would reduce NOx emissions by approximately 

0.29 tons per day beginning in 2015. The rules fulfill the relevant CAA §110 and 

part D requirements. Therefore, EPA staff recommends a full approval of Rules

1146 and 1146.1 pursuant to CAA §110(k)(3) and §301(a). 
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REFERENCES -

1. SCAQMD Rule 1146, Emissions of Oxides of Nitrogen from Industrial, 

Institutional, and Commercial Boilers Steam Generators and Process 

Heaters, as amended on November 1, 2013 and submitted to EPA on May 

13, 2014.

2. SCAQMD Rule 1146.1, Emissions of Oxides of Nitrogen from Small 

Industrial, Institutional, and Commercial Boilers, Steam Generators, and 

Process Heaters, as amended on November 1, 2013 and submitted to EPA 

on May 13, 2014.

3. SCAQMD Rule 1146, Emissions of Oxides of Nitrogen from Industrial, 

Institutional, and Commercial Boilers Steam Generators and Process 

Heaters, as amended on September 5, 2008 and submitted to EPA on July 

20, 2010.

4. SCAQMD Rule 1146.1, Emissions of Oxides of Nitrogen from Small 

Industrial, Institutional, and Commercial Boilers, Steam Generators, and 

Process Heaters, as amended on September 5, 2008 and submitted to 

EPA on July 20, 2010.

5. SCAQMD Rule 1146, Emissions of Oxides of Nitrogen from Industrial, 

Institutional, and Commercial Boilers Steam Generators and Process 

Heaters, as approved into the SIP on April 8, 2002.

6. SCAQMD Rule 1146.1, Emissions of Oxides of Nitrogen from Small 

Industrial, Institutional, and Commercial Boilers, Steam Generators, and 

Process Heaters, as approved into the SIP on September 6, 1995.

7. “NOx Emissions from Industrial/Commercial/Institutional (ICI) Boilers,” 

EPA-453/R-94-022, March 1994. 

http://www.epa.gov/glo/SIPToolkit/ctg_act/199403_nox_epa453_r-94-

022_ici_boilers.pdf

8. “Determination of Reasonably Available Control Technology and Best 

Available Retrofit Control Technology for Industrial, Institutional, and 

Commercial Boilers, Steam Generators, and Process Heaters,” CARB, 

July 18, 1991. http://www.arb.ca.gov/ractbarc/boilers.pdf.

9. “Issues Relating to VOC Regulation Cutpoints, Deficiencies, and 

Deviations,” (a.k.a., Bluebook) EPA OAQPS, May 25, 1988 (web citation).

10. “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).