United States Environmental Protection Agency, Region 9 

Air Division 

Technical Support Document 

for 

EPA’s Notice of Proposed Rulemaking 

for the 

California State Implementation Plan 

Imperial County Air Pollution Control District’s 

Rule 400.2, Boilers, Process Heaters and Steam Generators 

Prepared by: Idalia Perez 

April 2012 
Imperial County Air Pollution Control District (ICAPCD) 

Submitted Rule 

ICAPCD Rule 400.2, Boilers, Process Heaters and Steam Generators 

§ Adopted: February 23, 2010 

§ Submitted: July 20, 2010 

§ Determined complete: August 25, 2010 

Previous Rule Submittals 

There are no outstanding submittals of Rule 400.2. 

SIP-Approved Rule 

There is no SIP-approved version of Rule 400.2. 

Rule Summary 

Rule 400.2 regulates emissions of oxides of nitrogen (NOx) from boilers, process heaters and 

steam generators with a heat input rating of 5 MMBtu/hour or more. 

The emission limits in the Rule are (Section C): 

§ 30 ppm or 0.036 lbs/MMBtu for units operated on gaseous fuel 

§ 40 ppm or 0.052 lbs/MMBtu for units operated on liquid fuel 

§ 70 ppm for units operated on gaseous or liquid fuel with an annual capacity factor of 30% 

or less 

§ 120 ppm or 80% reduction for units operated on biomass fuel 

The rule language has various exemptions in Section D, including an exemption for coal fired 

units installed prior to December 31, 2009. 

Monitoring and recordkeeping requirements are contained in various provisions in Sections E, F, 

G and H. 

Effects on Emissions 

The staff report indicates that implementation of Rule 400.2 will reduce NOx emissions by 

approximately 143.3 tons per year. This reflects a 48% reduction of NOx emissions from the 

baseline for this source category. 

Rule Evaluation Criteria 

We have primarily used the following three criteria to evaluate Rule 400.2: 

Rule Stringency Section 172(c)(1) of the Clean Air Act (CAA) requires nonattainment 

areas to implement all reasonably available control measures (RACM), including such 

reductions in emissions from existing sources in the area as may be obtained through the 

adoption, at a minimum, of reasonably available control technology (RACT), as 

expeditiously as practicable. Ozone nonattainment areas classified as moderate or above 

must require RACT for all major sources of NOx. CAA § 182(b)(2) & (f); 40 CFR § 

51.912(a). In addition, SIP rules must implement Reasonably Available Control 
Measures (RACM), including Reasonably Available Control Technology (RACT), in 

moderate PM-10 nonattainment areas, and Best Available Control Measures (BACM), 

including Best Available Control Technology (BACT), in serious PM-10 nonattainment 

areas (see CAA sections 189(a)(1) and 189(b)(1)). The ICAPCD regulates an ozone 

nonattainment area classified as moderate (see 40 CFR part 81), thus Rule 400.2 must 

fulfill RACT requirements for NOx. The ICAPCD also regulates a serious PM-10 

nonattainment area, and is therefore subject to the requirement under sections 

189(b)(1)(B) and 189(e) of the Act to implement Best Available Control Measures 

(BACM, which includes Best Available Control Technology or BACT) for control of 

PM-10 and PM-10 precursor emissions. EPA determined that ICAPCD attained the 1997 

8-hour NAAQS for ozone based upon ambient air monitoring data showing the area had 

monitored attainment since the 2006-2008 monitoring period (74 FR 63309). This 

determination suspended the requirements related to attainment of the 8-hour ozone 

NAAQS.1

Enforceability CAA section 110(a)(2)(A) requires that regulations submitted to EPA for 

approval into a SIP must be clear and legally enforceable. 

SIP Revisions CAA section 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 

section 193 prohibits the modification of any SIP-approved control requirement in effect 

before November 15, 1990, in a nonattainment area.

Guidance and policy documents that we used to define specific enforceability, RACT, RACM 

and BACM requirements include the following: 

§ Issues Relating to VOC Regulation, Cutpoints, Deficiencies, and Deviations (the “Blue 

Book”), US EPA, OAQPS (May 25, 1988). 

§ Guidance Document for Correcting Common VOC and Other Rule Deficiencies, EPA 

Region IX (August 21, 2001, the “Little Bluebook”). 

§ State Implementation Plans; General Preamble for the Implementation of Title I of the 

Clean Air Act Amendments of 1990, 57 FR 13498 (April 16, 1992); 57 FR 18070 (April 

28, 1992). 

§ State Implementation Plans; Nitrogen Oxides Supplement to the General Preamble for 

the Implementation of Title I of the Clean Air Act Amendments of 1990 (the “NOX

Supplement to the General Preamble”), US EPA, 57 FR 55620 (November 25, 1992). 

§ State Implementation Plans for Serious PM-10 Nonattainment Areas, and Attainment 

Date Waivers for PM-10 Nonattainment Areas Generally; Addendum to the General 

Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990, 59 

FR 41998 (August 16, 1994).

 

1

 ICAPCD also regulates a nonattainment area under the 2006 24-Hour PM2.5 NAAQS. 40 C.F.R. § 81.305 (2010). 

By December 14, 2012, California must submit a revision to the State Implementation Plan (SIP) for this 

nonattainment area that provides for, among other things, implementation of all RACM as expeditiously as 

practicable (including RACT for existing sources). CAA § 172(a)(2)(A), (b) & (c)(1), 74 FR 58689 (Nov. 13, 2009). 

EPA will take action on this RACM demonstration in a separate rulemaking. 
§ PM-10 Guideline Document, US EPA 452/R-93-008 (April 1993).

§ 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

§ Alternative Control Techniques Document-- NOx Emissions from 

Industrial/Commercial/Institutional (ICI) Boilers, US EPA 453/R-94-022 (March 1994). 

http://www.epa.gov/ttn/catc/dir1/icboiler.pdf

§ Alternative Control Techniques Document-- NOx Emissions from Utility Boilers, US 

EPA 452/R-93-008 (March 1994). http://www.epa.gov/ttn/catc/dir1/utboiler.pdf

Evaluation of Rule Stringency 

We believe Rule 400.2 implements RACT for reasons including: 

- Both 1994 ACT documents mentioned above provide technical information including 

control techniques and achievable controlled NOx emission levels from boilers. Rule 

400.2 requirements are more stringent than the ACT. 

- The submitted rule is as stringent as CARB’s RACT/BARCT guidance. 

- Although we do not believe that exempting existing coal boilers from emission limit 

represent RACT in most cases, the District submitted additional information (letter 

from Monica Soucier to Andrew Steckel dated January 17, 2012; CBI redacted, 

attached) that demonstrates that retrofitting the only existing coal boiler in the 

Imperial County to burn gas would be too costly to be considered RACT. We 

reviewed the District’s economic analysis and have no information that undermines 

their analysis or conclusions that retrofitting the existing coal boiler is beyond their 

RACT threshold. 

Since no CTG has been issued recently for this activity, we do not have clear national guidance 

defining presumptive RACT. However, we believe the analysis summarized above sufficiently 

demonstrates that Rule 400.2 implements RACT at the time of rule adoption for boilers in 

Imperial County. 

According to the 2009 PM-10 SIP (see Table 3.3 in 2009 Imperial County State Implementation 

Plan for Particulate Matter less than 10 Microns in aerodynamic Diameter, Final, August 11, 

2009), fuel combustion accounts for less than 1% of the emission inventory for PM-10 in 

Imperial County. Since boilers are not a significant source of PM-10 in Imperial County, we do 

not believe they are subject to BACM requirements and thus we are not making a determination 

on the Rule’s ability to implement BACM. 

Evaluation of Enforceability and SIP Revision Criteria 

Recordkeeping and other compliance provisions in the rule ensure that the requirements are 

adequately enforceable. 

The submitted is not currently in the SIP, strengthening thus the requirements of the SIP when it 

is incorporated into the SIP. Therefore, we propose to determine that an approval of the submittal 

would comply with CAA sections 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 submitted SIP revision is more stringent than the existing SIP 

requirements. 

Suggested Rule Improvements 

Although not currently basis for rule disapproval, EPA recommends that the ICAPCD make the 

following improvement in the next revision of Rule 400.2. The District should consider lowering 

the emission limits in Section C to be consistent with South Coast Rule 1146 (adopted 

September 5, 2008) and analogous rules in other areas for liquid and gas fired units and to be 

consistent with Yolo-Solano Rule 2.43 and San Joaquin Rule 4352 for biomass fired units. 

Recommendation 

EPA staff recommends full approval of ICAPCD submitted Rule 400.2 for incorporation into the 

California Applicable SIP. 

Other References 

1. Submitted Rule 400.2 

2. Staff Report for Rule 400.2 

3. 2009 Imperial County State Implementation Plan for Particulate Matter less than 10 

Microns in aerodynamic Diameter, Final, August 11, 2009 

(http://www.imperialcounty.net/AirPollution/Attainment%20Plans/Final%20IC%202009

%20PM10%20SIP%20Document.pdf)