UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX AIR DIVISION

Technical Support Document 

for

EPA’s Direct Final Rulemaking

for the

California State Implementation Plan

Ventura County Air Pollution Control District Rule 54

Sulfur Compounds

Prepared by: James Shears

Reviewed by: Andrew Steckel

October 2014
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RULE IDENTIFICATION 

Agency: Ventura County Air Pollution Control District 

(VCAPCD)

SIP Approved Rule: Rule 54 – Sulfur Compounds

Amended – June 14, 1994

Submitted – July 13, 1994

EPA Approved – April 19, 2000 (65 FR 20913)

Subject of this TSD: Rule 54 – Sulfur Compounds

Amended – January 14, 2014

Submitted – May 13, 2014

RULE SUMMARY – VCAPCD Rule 54 limits emission of sulfur compounds to the 

atmosphere from fossil fuel combustion in Ventura. Rule requirements include 

both point of discharge limits and concentration limits at facility property lines for 

sulfur dioxide (SO2) and hydrogen sulfide (H2S). EPA approved VCAPCD’s 1994 

version of Rule 54 into the State Implementation Plan (SIP) in 2000. VCAPCD 

revised Rule 54 in 2014 largely to add a .075 ppm 1-hour SO2 facility property line 

concentration limit in paragraph B.2.a. consistent with the National Ambient Air 

Quality Standard (NAAQS) promulgated nationally in 2010. In 2011, the 

California Air Resources Board (CARB) asked EPA to designate all areas in 

California in attainment with this 2010 standard. EPA has not yet responded to 

this request, so VCAPCD is currently designated as being “better than the 

national standards” for the 1971 NAAQS for SO2. 

Other changes in Rule 54 relative to the SIP-approved rule include:

1. Section B.1. corrects a deficiency in the 1994 rule regarding the 

measurement of exhaust SO2 concentration from various combustion 

sources. Since different combustion sources are designed to function with 

different excess air input, it was unreasonable to set a single excess air 

requirement covering all sources in the 1994 rule. The amended rule 

corrects the measured SO2 concentrations to the appropriate exhaust gas 

oxygen content according to the type of combustion source. Exhaust 

oxygen content corrections would apply to stationary internal combustion 

engines, water heaters, boilers, steam generators and other combustion 

operations. 

2. Section B.2. adds various options for demonstrating compliance with the 

new .075 ppm 1-hour standard by modeling 3-year air monitoring data.
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3. Section C.2.f. clarifies that a 6-year averaging period applies to the flare 

gas volume allowance calculations.

4. Other minor formatting and editing revisions to aid clarity.

EVALUATION CRITERIA - The following criteria were used to evaluate the 

submitted rule. 

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 – As discussed above, Ventura County is designated as being 

“better than the national standards” for the 1971 NAAQS for SO2. The 

county has not been designated yet for the 2010 primary SO2 NAAQS. As a 

result, this rule does not need to comply with the specific sulfur 

nonattainment requirements in CAA §191, and only needs to comply with 

the general SIP requirements in CAA §110 that pertain to SO2 NAAQS. 

Therefore, there is no specific level of stringency, e.g., reasonably available 

control technology, required of this rule. 40 CFR 50.17 (National Primary 

Ambient Air Quality Standards for Sulfur Oxides (Sulfur Dioxide), June 22, 

2010) and SCAQMD Method 100.1 (Source Test Protocol for Determining 

Oxygen Corrected Pollutant Concentrations from Combustion Sources with 

High Stack Oxygen Content Based on Carbon Dioxide Emissions, March 3, 

2011) were used to help evaluate compliance with CAA §110. 

3. SIP Relaxation – Where previous versions of rules have been SIP 

approved, new submittals must comply with CAA §110(l) and §193 

regarding SIP relaxation.

EPA EVALUATION – The submitted VCAPCD Rule 54 is equivalent in stringency 

to the approved SIP, while the enforceability is enhanced. If ambient air monitoring 

shows concentrations above the current limits, the sources suspected of 

contributing to the exceedance would be required to demonstrate compliance with 

the .075 ppm ground level standard based on 3-year monitoring data as indicated 

in the 2010 Federal standard. This requirement enhances compliance 

enforceability. The rule enforceability is also strengthened by specifying the 

appropriate exhaust gas oxygen content be corrected to the SO2 values obtained 

for the various sources of combustion operation (stationary internal combustion 

engines, water heaters, boilers, etc.). 

1. The rule requirements and applicability are clear, and recordkeeping, 

reporting and other provisions sufficiently ensure that affected sources and 
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regulators can evaluate and determine compliance with Rule 54

consistently. 

2. The submitted rule is brought up to date with, and thus, is as stringent as 

the 2010 Federal SO2 standard, 40 CFR 50.17, and the exhaust oxygen 

correction factors for combustion SO2 monitoring are as stringent as other 

air districts’ methods, such as South Coast Air Quality Management District

Method 100.1.

3. We propose to determine that our approval of the submittal does 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 overall 

requirements in the submitted rule are more stringent than the existing SIPapproved control requirements that they would replace.

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. In the Exemptions Section C.1.c., we recommend the phrase, “but not 

limited to” be removed from the sentence such that it would be as follows: 

“The flaring event results from operational problems including emergency 

blowdowns, process upsets, power outages, and equipment breakdown.”

EPA ACTION – The submitted Rule 54 improves the SIP and complies with all 

relevant CAA requirements. Therefore, EPA staff recommends a full approval of 

Rule 54 pursuant to CAA §110(k)(3).

REFERENCES -

1. VCAPCD Rule 54, Sulfur Compounds, as submitted to EPA on May 13, 

2014.

2. VCAPCD Rule 54, Sulfur Compounds, as approved into the SIP on April 

19, 2000.

3. EPA, 40 CFR 50.17, National Primary Ambient Air Quality Standards for 

Sulfur Oxides (Sulfur Dioxide), June 22, 2010.

4. South Coast Air Quality Management District (SCAQMD), Method 100.1, 

Source Test Protocol for Determining Oxygen Corrected Pollutant 

Concentrations from Combustion Sources with High Stack Oxygen Content 

Based on Carbon Dioxide Emissions, March 3, 2011.

5. The Little Bluebook, EPA Region 9, August 21, 2001.

6. The Bluebook, EPA, May 25, 1988.