i

Project Team 

Jesse Madsen, Air Quality Specialist I 

Erin Scott, Air Quality Inspector I 

Steven Davidson, Air Quality Engineer II 

Anna Myers, Senior Air Quality Specialist 

Renee Chavez, Senior Air Quality Inspector 

Steve Leonard, Senior Air Quality Engineer 

Jessica Fierro, Program Manager 

Errol Villegas, Program Manager 

Mike Oldershaw, Compliance Manager 

Leonard Scandura, Permit Services Manager 

Rule 4311 (Flares)

Further Study 

2014 
Rule 4311 (Flares) Further Study 

September 16, 2014 

i Table of Contents | SJVUAPCD 

Table of Contents 

I. Executive Summary ..................................................................................................................................... 1 

II. Background .................................................................................................................................................... 4 

III. What is flaring? ............................................................................................................................................. 5 

A. General Equipment Description ......................................................................................................... 5 

B. General Process Description ................................................................................................................ 6 

IV. Valley Flares ................................................................................................................................................... 8 

V. Methodology .................................................................................................................................................. 9 

VI. Flare Minimization Plans ....................................................................................................................... 13 

A. Rule 4311 Flare Minimization Plan (FMP) Requirements .....................................................13 

B. Summary of Facilities Required to Submit FMPs .......................................................................14 

C. What was learned from collected FMPs ........................................................................................17 

VII. Annual Monitoring Reports .................................................................................................................. 18 

A. Rule 4311 Annual Monitoring Report Requirements ..............................................................18 

B. Submitted 2012 Annual Monitoring Reports ..............................................................................19 

C. What was learned from submitted Annual Monitoring Reports .........................................20

VIII. Reportable Flaring Event ....................................................................................................................... 21

A. Rule 4311 Reportable Flaring Event Requirements .................................................................21 

What is a Reportable Flaring Event?.................................................................................................. 21 

What data are required to be reported to the District in the Reportable Flaring Event 

report? ........................................................................................................................................................... 21 

B. Reportable Flaring Events ..................................................................................................................22 

C. Case Studies ..............................................................................................................................................22 

D. What was learned from collected Reportable Flaring Event reports ................................27 

IX. Regulatory Evaluation ............................................................................................................................. 28 

A. Federal Requirements ..........................................................................................................................28 

40 CFR 60 Subpart J .................................................................................................................................. 29

40 CFR 60 Subpart Ja ............................................................................................................................... 30 

40 CFR 60 Subpart OOOO ....................................................................................................................... 30 

B. State Requirements ...............................................................................................................................31 

C. Local Requirements at Other Air Districts ....................................................................................31 
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ii Table of Contents | SJVUAPCD 

SCAQMD Rule 1118 (Emissions from Refinery Flares) .............................................................. 31 

BAAQMD Regulation 12 Rule 11 (Flare Monitoring at Petroleum Refineries) and 

Regulation 12 Rule 12 (Flares at Petroleum Refineries) ........................................................... 32 

VCAPCD Rule 54 (Sulfur Compounds) .............................................................................................. 33 

SBCAPCD Rule 359 (Flares and Thermal Oxidizers) ................................................................... 33 

X. Valley Flaring Compared to Other Air Districts ............................................................................ 34 

A. Operations and Capacities ..................................................................................................................34 

B. Comparison of Emission Inventories ..............................................................................................36 

XI. Conclusion .................................................................................................................................................... 37 

Attachment: Rule Requirement Comparisons 
Rule 4311 (Flares) Further Study 

September 16, 2014 

1 Executive Summary | SJVUAPCD 

I. EXECUTIVE SUMMARY 

The San Joaquin Valley air basin (Valley) faces unique and unprecedented air quality 

challenges in attaining the federal air quality standards (also called National Ambient Air 

Quality Standards, or NAAQS). This further study report, analyzing District Rule 4311 

(Flares), is a continuation of the San Joaquin Valley Unified Air Pollution Control District’s 

(District) mission to improve the Valley’s air quality through proactive efforts to identify and 

enforce feasible emission reduction opportunities. 

Flares are employed to serve two basic functions: as an emission control device for VOC 

emissions, and/or as a safety device used in emergency situations, which include any 

situation or condition arising from a sudden and reasonably unforeseeable and 

unpreventable event beyond the control of the operator and requiring immediate 

corrective action to restore safe operation at the facility or site. 

District Rule 4311 was adopted in June 2002 to reduce emissions from flaring activities. 

Subsequent amendments to Rule 4311 have made it one of the most stringent rules in the 

nation for flaring activities. The most recent amendments, in June 2009, incorporated new 

requirements for operators to submit annual reports of reportable flaring events and annual 

gas flow from each flare subject to rule requirements, submit flare minimization plans (FMP) 

to the District, obtain approval of those FMPs, and operate under the conditions specified in 

the approved FMPs. The purpose of this report is to summarize results of a District analysis 

of FMPs and annual reports submitted to the District as a result of the 2009 rule amendments 

and to make a recommendation for future rule actions, if any, as a result of the study. 

Through this further study action, the District reviewed data from FMPs, annual monitoring 

reports, and reportable flaring events submitted to the District in July 2012 accounting for the 

fiscal year of 2011/2012, and reviewed New Source Performance Standards (NSPS) 

promulgated by EPA in 2012. In addition to the flare information review committed to in 

the plans, the District also reviewed the flare emission inventory in the Valley and 

analogous rules in other air districts in California. As a result of this extensive effort, the 

District made the following findings. 
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2 Executive Summary | SJVUAPCD 

1. Flare Emissions Contribute a Small Percentage to the Overall NOx 

Emissions Inventory 

A review of the flare emission inventory indicates that emissions from all flares 

operating in the Valley, regardless of permit status and requirements, 

contributed to 0.14% of the total annual NOx emitted from all Valley stationary 

and area sources in 2012. This is in part because these control devices are 

primarily engineered for emergency operation during process upsets and 

emergency situations and achieve 98% destruction efficiency when operated 

properly1. 

2. Rule 4311 is as Stringent as Other Air Districts’ Rules 

District analysis also confirmed that Rule 4311 is as stringent as similar rules in 

South Coast Air Quality Management District (SCAQMD), Bay Area Air Quality 

Management District (BAAQMD), Ventura County Air Pollution Control District 

(VCAPCD), and Santa Barbara County Air Pollution Control District (SBCAPCD). 

Those analogous rules have some minor differences in requirements, due to the 

differences in types of facilities and sizes of flares, which would not result in 

additional emission reductions if implemented in the Valley. Furthermore, Rule 

4311 has been confirmed by EPA in its most recent approval of amendments to 

the rule as satisfying Reasonable Available Control Technology (RACT) 

requirements. 

3. Flare Minimization Plans Contain Feasible Measures to Reduce Flaring 

In the Valley, 95 flares are either operated at petroleum refineries or have large 

enough flaring capacities to trigger the FMP requirements of Rule 4311. These 

flares are operated in multiple industries, including the oil and gas industry, 

wastewater treatment, and wine and cheese production. Operators with FMPs 

are including feasible measures in the FMPs and actively taking steps to reduce 

flaring at their facilities. 

4. Annual Monitoring Reports Assist with Enforceability 

Flares are subject to annual monitoring report requirements if the flare is 

subject to flare minimization plan requirements and can produce a reportable 

flaring event. Many Valley operators of flares are proactive in reducing flaring 

emissions by including Specific Limiting Conditions (SLCs) to their permits that 

limit the amount of flaring possible by their flare; consequently many of the 95 

flares subject to FMP requirements are not required to submit annual 

monitoring reports. For the 2011-2012 reporting period, 55 reports were 

submitted to the District and analyzed for this further study report. These 

 

1 U.S. EPA Office of Air Quality Planning and Standards, “Parameters for Properly Designed and Operated

Flares”. 2012. Retrieved from http://www.epa.gov/ttn/atw/flare/2012flaretechreport.pdf. 
Rule 4311 (Flares) Further Study 

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3 Executive Summary | SJVUAPCD 

reports were submitted from a variety of industries including, but not limited to, 

oil and gas production, wastewater treatment, and wine and cheese making. 

Operators of each of these flares are taking actions to reduce flaring at their 

facilities pursuant to their District approved FMPs. The annual monitoring 

reports add an important layer of enforceability to Rule 4311 by providing 

inspectors with verifiable data to ensure that larger sources of flaring are 

compliant. 

5. Reportable Flaring Events are Non-repeating 

A flaring event is considered a reportable flaring event if, during a 24-hour 

period, more than 500,000 standard cubic feet (scf) of vent gas is flared or sulfur 

oxide emissions are greater than 500 pounds. Of the 235 flares in the Valley, 21 

experienced reportable flaring events in the 2011-2012 reporting period. Most 

of these reportable flaring events were planned flaring events and were due to 

new equipment installations—some of which were new air pollution control 

devices—and repair or maintenance at the facilities. Since most of the events 

were due to equipment installation or repair, they are not likely to occur again in 

the near future. Of the gas flared, only 20% was salable quality. 

6. Flared Gas Occurs Under Abnormal Conditions 

To provide a more in-depth look at different flaring scenarios in the Valley the 

District performed case studies of flaring events at a light-oil production facility 

and a wastewater treatment plant (WWTP). Both facilities experienced 

abnormally high flaring activities over periods of several months. 

The by-product of light-oil production, generally referred to as off-gas, is a high 

quality gas; therefore, these facilities normally sell as much of the off-gas as 

possible. However, in this aberrant instance, the light-oil production facility 

discussed in the case study was unable to sell the gas during the 2012-2013 

reporting period because the sales transmission pipeline was offline for repairs. 

The facility had no other feasible options to flaring (see discussion later in 

report). 

Wastewater treatment plants produce waste gas that has a far lower heating 

value than the off-gas from oil production facilities and requires more extensive 

treatment prior to use; it is therefore not considered to be salable. In the WWTP 

case study, the flare gas produced by the facility is normally sent as a 

supplemental fuel to onsite equipment used to produce electricity and generate 

heat for some of the treatment processes. However, during the 2011-2012 

reporting period, the waste gases could not be sent to the equipment because 

additional air pollution control devices were being installed. 
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4 Background | SJVUAPCD 

As seen from the case studies, gas is typically flared only under abnormal 

conditions. Most facilities actively avoid flaring because these control devices 

only operate during process upsets and emergency situations. 

7. Rule 4311 Requirements are more stringent than the new 2012 Federal 

NSPS Requirements 

The 2012 promulgated NSPS requirements in 40 CFR 60 subparts Ja and OOOO 

do not implement requirements that are more stringent than those already 

implemented in District Rule 4311. Therefore, Rule 4311 satisfies the 

requirements of these NSPS requirements. 

This thorough and comprehensive further study evaluation has resulted in the District’s 

conclusion that operators of flares in the Valley are subject to the most stringent emission 

requirements and are proactively taking measures necessary to minimize emissions from 

flaring in the Valley by implementing feasible alternatives to flaring and committing to 

perform activities to reduce flaring. 

In light of these findings, the District recommends no rulemaking action for Rule 4311 at 

this time. 

II. BACKGROUND 

The development of the District’s 2012 PM2.5 Plan involved extensive research and analyses 

of technologies for potential opportunities to further reduce emissions of particulate matter 

(PM) and oxides of nitrogen (NOx), which is a predominant pollutant in the formation of fine 

particulate matter (particulate matter that is 2.5 microns or less in diameter, or PM2.5) and 

ozone. Although the results of the analyses for this plan did not indicate that regulatory 

action to further reduce flaring emissions would accelerate PM2.5 attainment, the District 

committed to continue evaluating flares through this further study measure. The 2009 rule 

amendments to Rule 4311, subjected facilities to new reporting requirements that require the 

submittal of annual flaring reports to the District every July beginning in 2012. While this did 

not provide adequate time for analysis and incorporation into the 2012 PM2.5 Plan, the 

District committed to perform a further study of these reports. Additionally, in 2012, EPA 

promulgated amendments to an existing New Source Performance Standard (NSPS) and 

promulgated a new NSPS. The District’s 2013 Plan for the Revoked 1-Hour Ozone Standard 

also committed to further analyze these opportunities as a part of this Further Study 

effort. Specifically, the two state implementation plans commit the District to evaluate 

submitted Flare Minimization Plans, Annual Monitoring Report data, Reportable Flaring Event 

data, and new NSPS requirements to identify and evaluate potential opportunities to further 

reduce emissions from these sources. This further study analysis satisfies requirements in 

both the 2012 PM2.5 Plan and the 2013 Plan for the Revoked 1-Hour Ozone Standard by 

presenting results of the aforementioned review and evaluations. 
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5 What is flaring? | SJVUAPCD 

III. WHAT IS FLARING? 

Flares serve two basic functions: as an emission control device for VOC emissions, and as a 

safety device during unforeseeable and unpreventable emergency situations. Any 

unreasonable restrictions on flaring could potentially result in catastrophic consequences 

which may lead to explosions resulting in loss of property, injury and potentially loss of 

human life. 

Flaring is a high temperature oxidation process used to burn mostly hydrocarbons of waste 

gases from industrial operations, with a destruction efficiency of 98 percent or greater. 

During combustion, gaseous hydrocarbons react with atmospheric oxygen to form carbon 

dioxide (CO2) and water. Flares used for emergency situations generally have large flaring 

capacities to enable them to handle large volumes of gas. Emergency situations, as defined 

in District Rule 4311, include any situation or condition arising from a sudden and 

reasonably unforeseeable and unpreventable event beyond the control of the operator and 

requiring immediate corrective action to restore safe operation at the facility or site. 

Examples of emergency events include, but are not limited to, equipment failure, natural 

disasters, external power curtailment, and acts of terrorism. Operators consider feasible 

alternatives to flaring because it is generally costly, and therefore avoided when possible. 

A. General Equipment Description 

There are two general types of flares: elevated and ground flares. Flares are further 

categorized by the height of the flare tip, and by the method of enhancing combustion by 

mixing at the flare tip (i.e., steam-assisted, air-assisted, pressure-assisted, or non-assisted). 

Elevated flares are more common in the Valley and have larger capacities than ground 

flares. In an elevated flare, a waste gas stream is fed through a stack and is combusted near 

the tip of the stack. An elevated flare consists of five components: a gas collection header 

(to collect gases from various process units); a proprietary seal; a water seal, or purge gas 

supply (to prevent flash back); a single or multiple-burner unit in the flare stack; and gas 

pilots and an igniter. Figure 1, below, depicts a typical configuration for a steam-assisted 

elevated flare. 

Ground flares, which are not typically found in the Valley, vary in complexity and can 

consist of either conventional flare burners discharging horizontally with no enclosures or 

multiple burners in refractory-lined steel enclosures. 
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6 What is flaring? | SJVUAPCD 

Figure 1 Flare Diagram2

B. General Process Description 

Complete combustion requires proper mixing of air and gas. Smoking may result from 

incomplete combustion, depending upon the flare gas components and the quantity and 

distribution of combustion air. Gases containing methane, hydrogen, CO, and ammonia 

usually burn without smoke, while gases containing heavy hydrocarbons may cause smoke. 

The tendency of a fuel to smoke or make soot is influenced by fuel characteristics and by 

the amount and distribution of oxygen in the combustion zone. Fuel characteristics include 

the carbon-to-hydrogen ratio and the molecular structure of the gases to be burned. Soot is 

eliminated by adding steam or air; hence, most industrial flares are steam-assisted and 

some are air-assisted. Flare gas composition is a critical factor in determining the amount 

of steam necessary. 

Air is supplied to the flame as primary and secondary air. Primary air is mixed with the gas 

before combustion. If the amount of primary air is insufficient, the gases entering the base 

 

2 EPA, “13.5 Industrial Flares”. 1995. http://www.epa.gov/ttnchie1/ap42/ch13/final/c13s05.pdf
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7 What is flaring? | SJVUAPCD 

of the flare are preheated by the combustion zone, and larger hydrocarbon molecules crack 

to form hydrogen, unsaturated hydrocarbons, and carbon. The carbon particles may 

escape further combustion and cool down to form soot or smoke. 

An external momentum force, such as steam injection, is used for turbulence and efficient 

mixing of air and waste gas, which promotes smokeless flaring of heavy hydrocarbon 

waste. Other external forces may also be used, including water spray, high velocity vortex 

action, or natural gas. External momentum force is rarely required in ground flares. 

Combustion efficiency depends on flame temperature, residence time in the combustion 

zone, vent gas flammability, auto ignition temperature, heating value measured in British 

thermal units per standard cubic feet (Btu/scf), and turbulent mixing. Through 

combinations of these factors, flares have a destruction efficiency of 98 percent or greater. 

Complete combustion converts all volatile organic compounds (VOCs) to CO2 and water. 

Flare gases must have a fuel value of at least 200 to 250 Btu/ft3 for complete combustion, 

otherwise another fuel must be added to achieve the required value. Flares for which 

supplemental fuel must be supplied are known as fired, or endothermic flares. In some 

cases, even flaring gases with the necessary heat content will require supplemental heat to 

ensure complete combustion. 

Figure 2 A visual example of complete versus incomplete combustion3

Flares are normally used to dispose of low volume continuous streams of gases but are 

designed to handle large quantities of gases associated with potential plant emergencies. 

As safety devices, it is necessary for flares to have high volume capacities so that they may 

prevent injury and loss of property during unforeseeable and unpreventable emergency 

situations. Emergency flaring occurs when necessary, to prevent an accident, hazard, or 

release of vent gas directly into the atmosphere. Emergency events may occur because of 

process malfunctions, relief valve leakage, power outages, and equipment breakdown. 

 

3 Image retrieved February 2012 from: http://www2.epa.gov/sites/production/files/2013-09/nei-air-toxicsflare-250.jpg 
Rule 4311 (Flares) Further Study 

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8 Valley Flares | SJVUAPCD 

Consequently, flare gas volumes can vary from a few cubic feet per hour during regular 

operations up to several thousand cubic feet per hour under emergency conditions. 

IV. VALLEY FLARES 

The flare source category subject to Rule 4311 requirements in the Valley is unique from 

other air districts in California because it incorporates such a diverse group of industries 

while other air districts generally limit the applicability of their analogous rules to 

petroleum refineries. There are approximately 235 flares in the Valley. Of those 235 flares, 

126 are exempt from District Rule 4311 because they are subject to the requirements of 

District Rule 4642 (Solid Waste Disposal Sites), subject to the requirements of 40 CFR 60 

Subpart WWW (Standards of Performance for Municipal Waste Landfills), subject to the 

requirements of 40 CFR 60 Subpart Cc (Emission Guidelines and Compliance Times for 

Municipal Solid Waste Landfills), or are not operated at a major source facility. Stationary 

sources that emit a total of less than ten tons per year of VOC and NOx emissions from all 

operations at the facility (including any flares) are not considered major sources, and are 

exempt from prohibitory requirements of the rule. However, all new or modified flares are 

subject to New Source Review (NSR) requirements including Best Available Control 

Technology (BACT) requirements, meaning they may be required to implement even more 

stringent controls regardless of whether or not they are subject to the requirements of Rule 

4311. 

 

The 109 flares in the Valley subject to the requirements in Rule 4311 are used by the 

following industries: 

• Gas plants 

• Heavy oil production / Thermally enhanced oil recovery 

• Light oil production 

• Refinery operations 

• Wastewater treatment plants 

• Cheese production 

• Wine 

• Dairy operations 

• Flat glass production 

• Correctional facility 

While much of flaring in the Valley occurs in the Southern region (Tulare and Kern 

counties) of the Valley, flaring activity also occurs in the Northern (San Joaquin, Stanislaus, 

and Merced counties) and Central (Madera, Fresno, and Kings counties) Valley. Of the 109 

flares subject to Rule 4311 requirements, 7 operate in the Northern region, 5 in the Central 

region, and 97 in the Southern region. 
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9 Methodology | SJVUAPCD 

The emissions from all 235 flares operating in the Valley contributed 0.14% of the total 

annual NOx emitted from all stationary and area sources in 2012. Flares are a small 

contributor to overall Valley emissions throughout the year in part because properly 

operated flares achieve at least 98 percent combustion efficiency4. The emissions 

represented in the table below represent emissions from all flaring activity in the Valley 

regardless of exemption status. 

Table 1 Annual Average Flare Emission Inventory (tons per day) 5

Pollutant 2012 2014 2015 2016 2017 2018 2019 

PM2.5 0.13 0.13 0.13 0.14 0.14 0.14 0.14 

NOx 0.38 0.39 0.39 0.39 0.39 0.39 0.39 

SOx 0.25 0.26 0.26 0.26 0.26 0.26 0.27 

District staff used reported volumes of gas flared to calculate an estimated emission 

inventory from Valley flaring and compared the calculations to the emission inventory for 

2012 in Table 1 above. The data comparison verified that the emissions inventory is 

representative of the actual flaring activity. 

V. METHODOLOGY 

This report is a culmination of the efforts of an interdepartmental team consisting of staff 

from Rule Development, Compliance, and Permits Services spanning a four-year 

implementation period since the June 2009 amendment of Rule 4311. Some of the actions 

performed during this implementation period include: 

• Working with facilities that operate flares to determine which units are subject to 

Rule 4311; 

• Collecting Flare Minimization Plans (FMP), Annual Monitoring Reports (AMR), and 

Reportable Flaring Event (RFE) reports; and 

• Review and determination of compliance with Rule 4311 requirements for FMPs, 

AMRs, and RFE reports. 

 

This further study report continues to build on previous efforts to examine this source 

category and identify and evaluate potential opportunities to reduce emissions by 

analyzing information collected during the previously described implementation period. 

 

4 U.S. EPA Office of Air Quality Planning and Standards, “Parameters for Properly Designed and Operated

Flares”. 2012. Retrieved from http://www.epa.gov/ttn/atw/flare/2012flaretechreport.pdf. 

5 Retrieved from the District’s 2012 PM2.5 Plan 

(http://www.valleyair.org/Air_Quality_Plans/PM25Plans2012.htm) 
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10 Methodology | SJVUAPCD 

To begin, District staff analyzed the 235 flare permits to determine which flares are subject 

to Rule 4311 requirements and how the facility operators are complying with applicable 

requirements. Based on information gathered, staff compiled all relevant data into the 

following categories: 

• Facility name 

• Facility description 

• Major source of NOx emissions (true or false) 

• Major source of VOC emissions (true or false) 

• Region (South, Central, or North) 

• Facility ID 

• Permit Number 

• Facility City 

• District inspection area 

• Equipment description 

• Subject to Rule 4311 requirements, other than recordkeeping (yes or no) 

• Flare rating (capacity) 

• Permit conditions that limit flaring (yes or now; if yes, description) 

• Flare type (emergency, standby, primary disposal 

• Greater than 5 MMBtu/hr (yes or no) 

• Summary of stated flare uses in FMP 

• Actions identified in FMP to minimize flaring 

• 2012 Annual Monitoring Report received (yes or no) 

• 2012 Reportable Flaring Events report received (yes or no) 

• 2012 Reportable Flaring Event analysis (number of events, number planned, and 

number unplanned) 

• Reportable Flaring Event link for more information 

• 2010 emissions inventory (MMscf) 

• 2010 annual gas flared from inspection reports 

• 2011 emissions inventory (MMscf) 

• Annual gas flared from AMR (7/11 – 6/12) 

• 2012 emissions inventory (MMscf) 

• Annual gas flared from annual monitoring report (7/12 – 6/13) 

Organizing, sorting, and consolidating the vast collection of data presented a significant 

challenge throughout this study, and a significant amount of staff resources were expended 

to thoroughly evaluate this information. As patterns and outlying data points were 

identified, staff began to sort the information into smaller, more manageable compilations 

that were used to answer specific questions about various Rule 4311 requirements and 

search for more patterns and outliers, all with the intent to identify additional 

opportunities to reduce emissions. 
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11 Methodology | SJVUAPCD 

The District began with the determination that out of the 235 flares being evaluated, 126 

flares are exempt from Rule 4311 requirements other than basic recordkeeping 

requirements due to one of the following reasons: non-major source, subject to other rules 

regulating landfills, or are not stationary. The remaining 109 flares in the Valley were 

determined to be subject to Rule 4311 requirements. Facilities subject to Rule 4311 

requirements were further categorized by whether or not they are subject to Flare 

Minimization Plans (FMP), Annual Monitoring Reports (AMR), or Reportable Flaring Event 

(RFE) submission requirements 

District staff determined that 95 facilities are subject to Flare Minimization Plan 

requirements and every flare permit was examined to determine whether an FMP had been 

submitted and approved by the District. If a facility did not submit an FMP for approval, 

staff investigated whether or not they were required to. When this study began, all 

facilities were in compliance with FMP requirements. 

The submitted FMPs were analyzed for patterns or irregularities, and evaluated whether: 

• FMPs account for all rule-required elements 

• Operators are identifying and evaluating opportunities to reduce flaring 

activities 

• Operators are incorporating identified opportunities that are determined to be 

feasible 

• Operators are not missing opportunities to further reduce flaring 

FMP review also focused on determining if there were common actions or best 

management practices identified in the FMPs that could be required for all facilities. As 

discussed further in the FMP section of this report (Section VI), actions identified in the 

FMPs are typically dependent on the facility and operation type, as well as the quality of gas 

being flared. Due to the variability of each facility’s needs, staff found no additional feasible 

actions/practices that could be added to Rule 4311 requirements. 

The next major analysis determined that 40 facilities were not subject to the requirements 

to submit Annual Monitoring Reports. Certain facilities were too small or had not utilized 

their flares, while the majority had accepted specific limiting conditions on their permits to 

operate (PTOs) which limited the amount of flaring the facility could conduct. This analysis 

also determined that 55 facilities are subject to AMR submittal requirements. Similar to 

the FMP analysis, staff began evaluating if the facility had submitted an AMR for the 

reporting period and, for the facilities that had not, District staff contacted the facilities to 

explain deficiencies and collect the missing information. 

The submitted AMRs were examined for the following information: 

• Percentages of total gas flared from each facility 

• Patterns of high or irregular flaring 
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12 Methodology | SJVUAPCD 

• Flaring in excess of limits committed to 

• Reasons for flaring 

Information gathered from the Annual Monitoring Reports allowed staff to gain a better 

understanding of how each facility was utilizing their flares, the measures taken to reduce 

flaring, and the amounts of gases being flared. Additionally, staff was able to use reported 

flaring volumes from the AMR to estimate emissions from reported flaring and compare 

those calculations to verify the accuracy of the emissions inventories. 

The final portion of the analysis evaluated data from facilities that experienced Reportable 

Flaring Events (RFEs) during this reporting period. District staff used the same 

comprehensive methods as were used for FMPs and AMRs to analyze the RFE reports for 

the following data: 

• Percentage of total volume flared from reportable events for each facility 

• Salable gas flared 

o Total volume 

o Total value 

o Average value 

• Total volume and percentage of non-salable gas flared 

• Causes of events (planned, unplanned, maintenance, new equipment installation, 

etc.) 

• Percentage of events due to each main type of cause

District staff conducted case studies of two facilities during the RFE analysis to gain a 

deeper understanding of how specific operations and events at those facilities affected 

their flaring activity. The two facilities were selected because they both experienced 

periods of abnormally high reportable flaring, and because one was representative of oil 

field flares, which include the majority of Valley flares. Staff analyzed the following 

information: 

• Type of facility 

• Operations performed at the facility 

• Reasons for flaring in general 

• Causes of reportable flaring events 

• Amount of flaring during the periods in question 

• Possible prevention measures 

• Additional opportunities to reduce flaring at the facility 

District staff also performed a regulatory evaluation that compared the requirements of 

Rule 4311 to those of NSPS and flare rules in other air districts. To understand the 

differences and similarities between Rule 4311 and NSPS, staff looked at fact sheets, 

guidance documents, and the actual NSPS text. Similarly, because the different rules for 

other air district have minor language and administrative differences, staff created a table 
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13 Flare Minimization Plans | SJVUAPCD 

(see Attachment) to organize and compare the main requirements of each district’s flare 

rules. Additionally, staff compared total numbers of flares, flare types, and flare capacities 

between the District and other major air districts in California. 

The following sections provide more details and explain the results of the further study as 

committed to in the 2012 PM2.5 Plan. 

VI. FLARE MINIMIZATION PLANS 

A. Rule 4311 Flare Minimization Plan (FMP) Requirements 

Sections 5.8 and 6.5 of District Rule 4311 require an FMP be submitted to and approved by 

the District for any petroleum refinery with a flare or any flare with a flaring capacity 

greater than or equal to 5.0 MMBtu/hr. The rule prohibits facilities subject to FMP 

requirements from flaring unless it is consistent with a District-approved FMP and all 

commitments in that FMP have been met. To ensure FMPs are up-to-date without undue 

redundancy in paperwork requirements from stakeholders, FMPs are to be updated every 

five years. Updates to the FMP are also required to address any new or modified 

equipment that requires an Authority to Construct permit and impacts emissions from the 

flare. 

An FMP submitted to the District pursuant to Section 6.5 of Rule 4311 shall include at least 

the following information: 

• Description and technical specifications for each flare and associated knock-out 

pots, surge drums, water seals and flare gas recovery systems 

• Process flow diagrams of upstream equipment and process units venting to each 

flare (with identification of type and location of control equipment) 

• Description of equipment, processes, or procedures the operator plans to install or 

implement to eliminate or minimize flaring, and planned date of installation or 

implementation 

• Evaluation of prevention measures to reduce flaring that has occurred or may be 

expected to occur during planned major maintenance activities, including startup 

and shutdown 

• Evaluation of preventative measures to reduce flaring that may be expected to occur 

due to issues of gas quantity and quality. This includes an audit of vent gas recovery 

capacity of each flare system, storage capacity for excess vent gas, and scrubbing 

capacity available for vent gas for use as a fuel; and shall determine the feasibility of 

reducing flaring through the recovery, treatment and use of the gas. 

• Evaluation of preventative measures to reduce flaring caused by the recurrent 

failure of air pollution control equipment, process equipment, or a process to 

operate in a normal or usual manner. Evaluation shall determine adequacy of 
Rule 4311 (Flares) Further Study 

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14 Flare Minimization Plans | SJVUAPCD 

existing maintenance schedules and protocols for such equipment. (A failure is 

recurrent if it occurs more than twice during any five year period as a result of the 

same cause) 

Further Study Commitment: 

Evaluate Flare Minimization Plans 

B. Summary of Facilities Required to Submit FMPs 

Of the 109 flares in the Valley subject to Rule 4311 requirements, 95 are subject to FMP 

requirements, all of which have been submitted by the time of this further study report. 

The remaining 14 flares are not required to submit FMPs to the District because they have 

a flaring capacity less than 5.0 MMBtu/hr and are operated at facilities other than 

petroleum refineries. 

To further illustrate the wide applicability of Rule 4311, a summary of the 95 submitted 

FMPs is presented in table 2 and is organized by industry type. 
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15 Flare Minimization Plans | SJVUAPCD 

Table 2 Submitted FMPs Summarized by Industry 

Industry Summary Qty

Cheese production 1 

Wine 2 

Correctional Facility 1 

Crude oil and natural gas production 14 

Crude oil production 1 

Crude petroleum and natural gas production 2 

Gas plant 2 

Light oil production 5 

Natural gas processing 4 

Natural gas production 2 

Natural gas transmission 2 

Oil and gas production 13 

Oil and natural gas production 29 

Petroleum and natural gas production 1 

Petroleum production 1 

Petroleum refinery 7 

Dairy 1 

Flat glass 1 

Wastewater 6 

Total 95 

Pursuant to Section 6.5.1 of rule requirements, operators are required to evaluate 

preventative measures to reduce flaring during planned major maintenance activities, 

flaring due to issues of gas quantity or quality, and flaring caused by recurrent failure of 

equipment. 

Each operator of the facilities described above performed such evaluations and presented 

findings in the FMPs they submitted to the District. Table 3 includes a summary of actions 

identified in FMPs to minimize flaring, along with the facility types that committed to the 

actions. The actions identified are a sampling from multiple facilities within each category, 

and not every facility in the category committed to all of the FMP actions shown. 
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Table 3 Summary of FMP Measures 

FACILITY 

CATEGORY ACTIONS IDENTIFIED IN FMP TO MINIMIZE FLARING* 

Oil and Gas 

Production 

and 

Transmission 

Include permit limit on gas flared daily and annually 

Streamline startup, shutdown, and maintenance procedures to minimize 

equipment downtime, thereby minimizing flaring 

Hydrogen sulfide scrubbing of flare gases to condition for sale6

Inject flare gas in DOGGR-approved wells 

Use other combustion devices such as glycol re-boiler/thermal oxidizer 

Wastewater 

Treatment/ 

Reclamation 

Install new equipment to combust digester gas in internal combustion 

engines, fuel cells, and process heaters 

Install equipment to allow digester gas storage and conditioning for 

greater use in turbines (additional storage is minimal and only capable 

of handling excess gas during minor process upsets)

Wine 

Production 

Burn flare gas in steam generation boilers; coordinate plant operations 

that generate the flare gas with production operations requiring steam 

Cheese 

Production Modify boiler to combust a natural gas/digester gas blend 

Flat Glass 

Manufacturing 

Reduce idle time during calibration and purge test to reduce necessary 

flaring 

Dairy Farming Install additional gensets (electricity generation equipment located near 

the end user) to combust more produced biogas 

Depending on the facility type, and the quality of flare gas produced, some of the above 

measures may not be feasible for all facilities. 

For oil and gas production, the flare gas produced is often in excess of what could be used 

onsite to power equipment. For these facilities, flares are generally used only under 

abnormal conditions, as the flare gas is usually high enough quality to sell for use at other 

facilities. 

For facilities other than oil and gas production, the gas produced is usually a much lower 

heating value and requires conditioning if combusted for electrical generation or process 

 

6 BioPath, LLC. (2013). Hydrogen Sulfide H2S Scrubber. Retrieved from http://biopathfps.com/hydrogensulfide-h2s-scrubber/ 
Rule 4311 (Flares) Further Study 

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17 Flare Minimization Plans | SJVUAPCD 

heating. Expensive modifications or new equipment is often required to allow said 

combustion activities, and the flare gas is sometimes of too low quality or quantity to make 

these installations cost effective. Additionally, depending on the combustion equipment 

used, there is no guarantee that emissions will be lower because flares are already effective 

control devices. 

The majority of the operators are already performing all activities possible to reduce 

flaring at their facilities, as confirmed in the FMP submittals. As such, most operators were 

not able to identify additional actions above and beyond those already implemented at 

their facilities to further minimize flaring, and those that did identify feasible alternatives 

committed to them in the FMPs submitted to the District. 

C. What was learned from collected FMPs 

The majority of the 95 Valley flares with FMPs are standby flares, which means they are 

only utilized when needed such as during maintenance or to dispose of excess flare gas, and 

are not used as a method of primary disposal for waste gases. Twelve of the 95 flares are 

permitted specifically for emergency use only and another three serve a primary purpose 

as both an emergency flare and a standby flare. See figure 3 for a summary of the primary 

uses of flares with FMPs in the Valley. 

Only three flares in the Valley are permitted to be used as primary disposal devices. Two of 

the three flares are used at an oil and natural gas production facility as a VOC control 

device for vapors displaced from trucks during load-out operations pursuant to 

requirements in District Rule 2201 (New and Modified Stationary Source Review Rule). 

The facility minimizes flaring by limiting use of the flares to comply with Rule 2201 and not 

using them for planned major maintenance, start up or shut down activities, or for control 

of emissions caused by equipment failure or process malfunctions. The third flare is used 

at a cheese making facility for primary disposal of methane gas generated by the 

wastewater anaerobic digester at the facility. However, the cheese making facility 

committed to modify an on-site boiler to combust a natural gas/digester gas blend to 

reduce flaring in the facility’s FMP. 
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18 Annual Monitoring Reports | SJVUAPCD 

Figure 3 Primary Purpose of Valley Flares 

Review of the information in the FMPs verified that operators are performing actions to 

reduce flaring at their facilities including not using the flares, permitting them for 

emergency use only, not using them for major maintenance as a standard practice, burning 

gases in alternative devices when possible, and limiting gas flow to the flares. 

VII. ANNUAL MONITORING REPORTS 

A. Rule 4311 Annual Monitoring Report Requirements 

The operator of a petroleum refinery flare or any flare with a flaring capacity equal to or 

greater than 50 MMBtu/hr (§5.10, 6.6, 6.7, 6.8, 6.9, 6.10), as appropriate, is required to 

submit an annual monitoring report to the District no later than July 31st of each calendar 

year (§6.2.3). 

Pursuant to Rule 4311 Section 6.2.3, the annual monitoring report submitted to the District 

shall contain the following information: 

• Total volumetric flow of vent gas (§6.2.3.1) 

• Hydrogen sulfide content, methane content, and hydrocarbon content of vent gas 

(§6.2.3.2) 

• If vent gas composition is monitored by a continuous analyzer(s): average total 

hydrocarbon content by volume, average methane content by volume, and 

depending upon the analytical method used, total reduced sulfur content by volume 

or hydrogen sulfide content by volume of vent gas flared for each hour of the month 

(§6.2.3.3) 
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19 Annual Monitoring Reports | SJVUAPCD 

• If the flow monitor measures molecular weight, the average molecular weight for 

each hour of each month (§6.2.3.4) 

• For any pilot and purge gas used, the type of gas used, the volumetric flow for each 

day and for each month, and the means used to determine flow (§6.2.3.5) 

• Flare monitoring system downtime periods, including dates and times (§6.2.3.6) 

• For each day and each month provide calculated sulfur dioxide emissions (§6.2.3.7) 

• A flow verification report for each flare (§6.2.3.8) 

Further Study Commitment: 

Evaluate Annual Monitoring Report Data 

B. Submitted 2012 Annual Monitoring Reports 

Flares are subject to the annual monitoring report requirements if the flare is subject to 

flare minimization plan requirements and can produce a reportable flare event; however, 

many Valley operators of flares are proactive in reducing flaring by having specific limiting 

conditions added to their District permits that limit the amount of flaring. As a result, many 

of the 95 flares subject to FMP requirements do not produce reportable flare events and 

are not required to submit annual monitoring reports. At the time of this further study 

effort, 55 annual monitoring reports have been submitted to the District. The following 

table is a summary of annual monitoring reports sorted by industry type. 
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20 Annual Monitoring Reports | SJVUAPCD 

Table 4 Submitted Annual Monitoring Reports Summarized by Industry 

Industry Summary Qty 

Correctional Facility 1 

Cheese Production 1 

Winery 1 

Oil and Gas Production 6 

Crude Petroleum and Natural Gas 1 

Crude Oil and Natural Gas Production 7 

Oil and Natural Gas Production 15 

Natural Gas Transmission 2 

Waste Water Reclamation 1 

Gas Plant 2 

Petroleum and Natural Gas production 1 

Petroleum refining 7 

Natural Gas Production or Processing 6 

Light Oil Production 4 

Total 55 

C. What was learned from submitted Annual Monitoring Reports 

As committed to, the District collected and analyzed Annual Monitoring Reports. 

Information from these AMRs allowed the District to evaluate the total amount of vent 

gases combusted and their compositions from each of the 55 flares. This information 

allowed the District to calculate the amount of emissions from the reported flaring and 

compare those values to verify the accuracy of the emissions inventory for flares. 

As can be seen above, the annual monitoring reports represent a variety of industries in the 

Valley. Of the flares summarized in the 55 annual monitoring reports, only one is used as a 

primary disposal device, one is dormant, and eleven are designated for emergency use 

only. The remaining flares are standby flares. Many facilities have specific limiting 

conditions in their permits that limit the amount of flaring allowed to less than the 

threshold for reportable flaring events; another example of operators committing to keep 

flaring at their operations reduced. Operators of all of the flares with annual monitoring 

reports are also actively taking measures pursuant to their FMPs to reduce flaring at their 

facilities; a few examples include having the flares permitted for emergency use only, 

rendering flares dormant, and coordinating efforts at the facility to reduce flaring. Annual 

monitoring reports are a valuable resource for understanding the activities of Valley flares. 

The information in these reports offers additional evidence that flaring is generally a last 

resort for facilities. The District will continue to collect and analyze these reports annually. 
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21 Reportable Flaring Event | SJVUAPCD 

VIII. REPORTABLE FLARING EVENT 

A. Rule 4311 Reportable Flaring Event Requirements 

What is a Reportable Flaring Event? 

A flaring event is considered a “Reportable Flaring Event” if more than 500,000 standard 

cubic feet (scf) of vent gas is flared per calendar day, or where sulfur oxide emissions are 

greater than 500 pounds per calendar day. A reportable flaring event ends when it can be 

demonstrated that the integrity of the water seal has been maintained sufficiently to 

prevent vent gas to the flare tip, or when the rate of flow of vent gas falls below 0.12 feet 

per second (§3.31). Assuming an estimated heating value for flare gas of 1,000 Btu/scf, a 

flare must have a capacity greater than or equal to 20.8 MMBtu/hr to achieve a reportable 

flaring event, although most flares commonly operate at a small fraction of maximum 

capacity. Additionally, some low quality waste gases can have heating values of 200-300 

Btu/scf, which would lower the minimum capacity for reportable flaring events. 

Reportable Flaring Event requirements are applicable to the operator of a flare subject to 

FMP requirements with the exception of flares that the operator can verify are not capable 

of producing reportable flare events (§5.10). Annual reports summarizing all Reportable 

Flaring Events shall be submitted to the District no later than July 31st of each year (§6.2.2). 

What data are required to be reported to the District in the Reportable Flaring Event 

report? 

The report shall summarize all Reportable Flaring Events that occurred during the 

previous 12 month period (§6.2.2). The report shall include, but is not limited to the 

following: 

• The results of an investigation to determine the primary cause and contributing 

factors of the flaring event (§6.2.2.1) 

• Any prevention measures considered or implemented to prevent recurrence 

together with a justification for rejecting any measures that were considered but not 

implemented (§6.2.2.2) 

• If appropriate, an explanation of why the flaring was an emergency and necessary to 

prevent accident, hazard or release of vent gas to the atmosphere, or where, due to a 

regulatory mandate to vent a flare, it cannot be recovered, treated and used as a fuel 

at the facility (§6.2.2.3) 

• The date, time, and duration of the flaring event (§6.2.2.4) 
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22 Reportable Flaring Event | SJVUAPCD 

Further Study Commitment: 

Evaluate Reportable Flare Event Data 

B. Reportable Flaring Events 

The reportable flaring events data presented in this report are from the 2011-2012 fiscal 

year. While 2012-2013 reportable flare event reports and data have been submitted to the 

District at the time of this further study, a complete analysis of these more recent reports 

has not been incorporated into this further study because doing so would require an 

additional year of District analysis. However, the District analyzed 2012-2013 reportable 

flaring events data for the two case studies presented below. 

Of the 109 flares subject to Rule 4311, 21 flares generated 395 reportable flaring events. 

The following table summarizes the amount of gas flared during reportable flaring events. 

This information is organized by industry type. 

Table 5 Summary of Total Reportable Flare Events (MSCF) 

Industry Summary Qty of 

Flares

Reportable Flare 

Events – Total 

(MMscf) 

Crude Oil and natural gas production 3 27.8 

Gas plant 2 12.0 

Light oil production 3 7.7 

Natural gas processing and production 5 42.8 

Oil and natural gas production 4 52.5 

Petroleum and NG production 1 20.9 

Petroleum refining 2 59.4 

Wastewater reclamation facility 1 124.2 

Total 21 347.4 

C. Case Studies 

Two case studies were performed to provide a more in-depth evaluation of flaring 

activities in the Valley. As the oil and gas related industries represent a majority of the 

operations in the Valley performing flaring activities, the first case study focuses on an oil 

field flare. The second case study is of flaring activities at a wastewater treatment plant; 

this facility was selected because it had an unusual amount of flaring during the reporting 

period. 
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23 Reportable Flaring Event | SJVUAPCD 

LIGHT OIL PRODUCTION 

Vintage Production California LLC operates as a subsidiary for Occidental Petroleum 

Corporation at several facilities in California. One facility located in North Shafter (VPC 

North Shafter) was selected for a case study because it is representative of oil field flares in 

the Valley and because it experienced a period of abnormally high flaring activity during 

the reporting period. 

Flare gas at oil production facilities is mostly composed of high quality, high energy content 

compounds like methane, ethane, propane, and butane, and typically transmitted either to 

a sales gas line or to a gas plant pipeline where it is treated prior to use or sale. With an 

estimated heating value of 1000 Btu/scf for this gas, it is a valuable commodity. The 

facilities producing this gas generally try to use or sell as much as possible, but must 

sometimes flare for various reasons, most commonly for safety during emergency and 

process upset situations. Other reasons for flaring include gas produced in excess of 

commercial demand or in excess to what can be burned as process gas, vapors collected 

from the tops of tanks as they are filled, process upsets, equipment changeover or 

maintenance, well tests, production shut-down, gas of insufficient volume to financially 

warrant treatment prior to sending to a pipeline, or when there is not a gas plant pipeline 

available. 

VPC North Shafter operates a 41.7 MMBtu/hr Coanda tip flare with liquid knockout and 

sulfur knockout vessels. It is permitted at a gas rate of no more than 4.0 MMscf/day and 

438 MMscf per year. The emission rates (lb/MMscf) are not to exceed 20 for PM10, 68 for 

NOx, 33 for VOC, or 38 for CO. 

Of the 395 reportable flaring events in 2011-2012 in the Valley, nine were at VPC North 

Shafter, all of which were planned maintenance. In contrast, the facility performed 157 

reportable flaring events in 2012-2013; all of which were for planned shutdown for repair 

and maintenance because Chevron, which normally pipes the flare gas to its Kern River oil 

field after purchasing it from VPC North Shafter, was repairing a pipeline.7 The total 

volume flared during reportable events at VPC North Shafter in 2011-2012 was 13.1 

MMscf, compared to 283.3 MMscf in 2012-2013. 

During the 2012-2013 reporting period, there were four months of nearly constant flaring. 

Despite the abnormally high flaring activity, NOx emissions from these reportable flaring 

events were 9.6 tons for the entire reporting period, an average of 0.06 tons per day. The 

total value flared during the 2012-2013 reportable events was an estimated $1.4M. The 

 

7The Bakersfield Californian, “The Sound and the Fury”. 2012 

http://www.bakersfieldcalifornian.com/business/x871558971/The-sound-and-the-fury-Gas-flare-wears-onShafter-area-residents 
Rule 4311 (Flares) Further Study 

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24 Reportable Flaring Event | SJVUAPCD 

sales transmission line was closed due to conditions beyond the control of the facility. 

Therefore, flaring activities conducted in 2012-2013 at VPC North Shafter were extremely 

abnormal and unlikely to occur in the future.

Internal combustion engines (IC engines) can combust low-sulfur well vapors typical of 

light oil production sources such as the VPC North Shafter facility. Increased use of IC 

engines, where available and feasible, can reduce flaring activities; however, it would not 

decrease emissions beyond what would be reduced by the flare. Flares are emission 

control devices that operate at 98% control efficiency. The use of IC engines in the Valley is 

regulated through District Rule 4702 (Internal Combustion Engines). Depending on the 

size, type, and total hours of usage of the engine, using IC engines in place of flaring could 

actually increase emissions. Furthermore, the addition of IC engines to a facility requires 

additional controls (Best Available Control Technology), monitoring, and reporting thus 

increasing the cost of using the waste gas in this type of equipment. 

Measures listed in the VPC North Shafter FMP include: 

• Flaring frequency and gas volume flared is insufficient to economically justify 

installation of redundant equipment 

• In the event of a planned shut down by end user, and/or major maintenance 

activities to the sales gas compressor, gas production will be curtailed to the extent 

possible without hampering oil production 

• The gas process equipment is operated in a manner to minimize disruptions from 

repair and/or maintenance 

• Sales gas compressor has a thorough, regular maintenance schedule to prevent 

major malfunctions that result in longer periods of flaring 

• VPC cooperates with end user to minimize down time and flaring 

The VPC case study offers evidence that oil production facilities take actions to minimize 

flaring and instead attempt to transmit the gas for sale or use in other locations. Occasional 

installation, maintenance, or repair of critical items such as transmission lines can cause 

abnormally high flaring activity, but these are typically one-time events. Because light oil 

production facilities already sell or utilize as much flare gas as possible, no feasible 

alternatives are available. 

WASTE WATER TREATMENT PLANT—Fresno/Clovis Regional Wastewater 

Treatment Plant, South Fresno 

The Fresno/Clovis Regional Wastewater Treatment Plant (WWTP), located in south 

Fresno, was selected for this case study because it experienced an abnormally high amount 

of flaring and is not a part of the petroleum and natural gas industry. 
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25 Reportable Flaring Event | SJVUAPCD 

The 80 million gallon per day (MGD) facility treats wastewater through primary treatment, 

secondary treatment, and anaerobic digestion. Digester gas from the WWTP is produced 

during anaerobic digestion, a process that exploits a variety of bacteria in an oxygen-free 

environment to reduce organic matter in bio-solids8. Anaerobic digesters are capable of 

producing high-quality, high energy content methane that can be used for electricity 

generation or to supply heat needed to complete the digestion process. However, digester 

gas requires treatment to remove hydrogen sulfide (H2S) and sometimes requires 

dehydration, filtering, or CO2 removal. Digester gas, which usually has a methane content 

of greater than 60%, can be a suitable natural gas fuel substitute for use in boilers, hot 

water heaters, reciprocating engines, turbines, and fuel cells.9

According to the District-approved FMP for this facility, digester gas is consumed to create 

electricity and provide heat for the digesters. The WWTP uses two 3.4 Megawatt (MW) 

turbine engines and one 16.7 MMBtu/hr process boiler that are almost completely fueled 

by digester gas. Because there is no significant gas storage capacity, any excess digester 

gas or gas produced during interruptions to the turbines or boiler must be flared. 

Flaring at the WWTP is performed by a 36.3 MMBtu/hr John Zink waste gas flare that was 

installed to replace three older, less efficient flares. The fully automated, enclosed ground 

flare is designed to burn digester gas without auxiliary fuel at a maximum flow rate of 

1,100 cubic feet per minute (CFM). NOx emissions are less than 0.06 lb/MMBtu, and SOx is 

controlled by reducing H2S concentrations in the digester gas. To fulfill commitments in 

the FMP, the facility installed a small digester gas storage tank, installed additional digester 

gas conditioning, and increased the allowable digester gas fuel for the turbines from 50% 

to 100%. The storage tank is capable of holding gas for small periods, such as during 

switchover between turbines, and the gas conditioning allows the use of selective catalytic 

reduction (SCR) on the turbines. 

The WWTP has reduced the volume of gas flared from 174.7 MMscf in 2004 to 50.4 MMscf 

in 2013; however, the 2011-2012 reporting period included abnormally high flaring 

activity. During this period, the turbines were out of service to allow installation of 

selective catalytic reduction (SCR) control devices for compliance with District Rule 4703 

(Stationary Gas Turbines). As a result, a large portion of the digester gas was flared. Out of 

395 total reportable flaring events in the Valley during the 2011-2012 reporting period, 

164 occurred at the WWTP. Those events accounted for 36 percent of the total volume of 

gas flared during reportable events, more than three times the next highest volume at any 

 

8City of Fresno Wastewater Management Division. Retrieved from 

http://www.fresno.gov/Government/DepartmentDirectory/PublicUtilities/Wastewater/default.htm on 

1/26/14. 

9 DOE, “Wastewater Digester Gas can Produce High Quality Methane Fuel for Federal Facilities.” 2005. 

http://www1.eere.energy.gov/femp/news/news_detail.html?news_id=8961 
Rule 4311 (Flares) Further Study 

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26 Reportable Flaring Event | SJVUAPCD 

facility. The graph below shows the percent of total volume flared from each source that 

experienced reportable flaring events during the reporting period. 

Figure 4 Percent of Reportable Flaring from All Sources 

All of the events were planned, and the majority (127 events) was for the installation of the 

SCR units. The remaining 37 events were due to maintenance or excess digester gas 

production. By contrast, the 2012-2013 reporting period showed only 46 reportable 

flaring events, all of which were for regular activities except one due to failure of a turbine. 

Because the majority of flaring events during the 2011-2012 reporting period were due to 

installations and are therefore one-time events, they are not part of normal facility 

operations. 

The WWTP case study offers further evidence that facilities in the Valley are already 

implementing feasible measures to reduce flaring. The digester biogas is a valuable 

resource that the WWTP uses to provide a significant portion of its electricity demands and 

process heating input. The facility implemented measures identified in the FMP to increase 

digester gas usage onsite, install a gas storage tank, and further condition the gas to allow 

for additional air pollution control equipment to be operated. 

0

5

10

15

20

25

30

35

40

A B C D E F G H I J K L M

Percent of Total Volume Flared from 

Reportable Flaring Events

Facility (Facility 'A' is Fresno/Clovis Regional WWTP)
Rule 4311 (Flares) Further Study 

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27 Reportable Flaring Event | SJVUAPCD 

D. What was learned from collected Reportable Flaring Event reports 

The majority of reportable flaring events during the 2011-2012 reporting period were 

planned (82.5%) and only 20% involved salable flare gas. This shows that measures have 

already been implemented to reduce the number of emergency events. Over half of the 

reportable flaring events were due to new installations, and as such are unlikely to be 

repeated. The figure below shows the percent of events due to the different reasons for 

reportable flaring events. 

Figure 5 Reasons for Reportable Flaring Events 

The total value of all reportable flaring events was estimated at $560,000, of which only 

$190,000 occurred due to planned events. Facilities in the Valley are already implementing 

feasible alternatives to flaring because flare gas is a valuable commodity for sale or use 

onsite. 

The two case studies of typical Valley facilities show that most facilities attempt to sell or 

use as much flare gas as possible. The greatest flaring during the 2011-2012 period was 

from a wastewater treatment plant, where the option to curtail operations does not exist, 

due to the necessary nature of the facility. The excessive flaring at that facility was 

required to install more air pollution control equipment, and was therefore a one-time 

event that will benefit Valley air in the long term. 

Maintenance/ 

Repair

19%

Equipment 

Installations

51%

Startup/ 

Shutdown

13%

Equipment 

Failure

8%

Power Outage

5%

Reason Unkown

4%
Rule 4311 (Flares) Further Study 

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28 Regulatory Evaluation | SJVUAPCD 

IX. REGULATORY EVALUATION 

In evaluating District Rule 4311, the U.S. Environmental Protection Agency (EPA) identified 

three core requirements needed to satisfy RACT for flares: 

• Flare minimization plans 

• Monitoring and reporting flare events 

• Causal analysis for large flare events10

Upon comparing District Rule 4311 to analogous rules for these criteria, EPA deemed the 

District rule as being at least as stringent as RACT and finalized approval of the District’s 

2009 amendments to Rule 4311 on November 3, 2011.11 Additionally, EPA finalized a 

partial approval of the 2009 RACT demonstration report on January 10, 2012 and 

confirmed this rule as still being at least as stringent as established RACT requirements.12 

For purposes of this further study, the regulatory evaluation will consist of actions 

occurring after January 2012. 

A. Federal Requirements 

Rule 4311 is as stringent as, or more stringent than the applicable federal NSPS (40 Code of 

federal Regulations (CFR) 60.18 – General Control Device Requirements)13 and the flares 

section of the Consolidated Federal Air Rule (40 CFR 65.147 – Flares)14, and the applicable 

federal National Emission Standards for Hazardous Air Pollutants (40 CFR 63, Subpart SS – 

National Emission Standards for Closed Vent Systems, Control Devices, Recovery Devices 

and Routing to a Fuel Gas System or a Process)15. There are no applicable Control 

Techniques Guidelines, Alternative Control Techniques, or Maximum Achievable Control 

Technology requirements for flares. 

In 2012, EPA modified an existing NSPS for flares (40 CFR 60 Subpart Ja)16 and added a 

new NSPS (40 CFR 60 Subpart OOOO)17, both of which are applicable to this source 

 

10 EPA TSD (Analysis of SJVUAPCD’s Rule 4311), http://www.regulations.gov/#!documentDetail;D=EPA-R09-

OAR-2011-0601-0022

11 76 FR 68106, http://www.gpo.gov/fdsys/pkg/FR-2011-11-03/pdf/2011-28391.pdf 

EPA Proposed approval 76 FR 52623, http://www.gpo.gov/fdsys/pkg/FR-2011-08-23/pdf/2011-21368.pdf 

TSD: http://www.regulations.gov/#!documentDetail;D=EPA-R09-OAR-2011-0601-0022 

12 77 FR 1417, http://www.gpo.gov/fdsys/pkg/FR-2012-01-10/pdf/2012-139.pdf

13 40 CFR 60.18. http://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol6/pdf/CFR-2010-title40-vol6-sec60-

18.pdf 

14 40 CFR 65.147. http://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol15/pdf/CFR-2010-title40-vol15-

sec65-147.pdf 

15 40 CFR 63, subpart SS. http://www.ecfr.gov/cgibin/retrieveECFR?gp=&SID=1a65b68f3f3a44dbf44870e8aec64884&r=SUBPART&n=40y11.0.1.1.1.18 

16 40 CFR 60, subpart Ja http://www.law.cornell.edu/cfr/text/40/part-60/subpart-Ja 
Rule 4311 (Flares) Further Study 

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29 Regulatory Evaluation | SJVUAPCD 

category. The District’s Permit Services Department already evaluates NSPSs on a case-bycase basis to ensure the relevant flares comply with all federal requirements as they are 

promulgated, therefore, adding any requirements from subparts Ja and OOOO would not 

achieve additional emission reductions from this source category. 

40 CFR 60 Subpart J 

The NSPS for refinery flares constructed or modified after June 11, 1973 are regulated in 40 

CFR Part 60, Subparts A and J. Subpart A applies to flares as general control devices, 

specifying design and operational criteria for new and modified flares. Requirements 

include operating the flare with no visible emissions, monitoring the presence of the pilot 

flame with a thermocouple or equivalent device, and meeting heat content and maximum 

tip exit velocity specifications. Rule 4311 is as stringent as Subpart A. 

40 CFR 60, subpart J - NSPS for petroleum refineries applies to the affected facilities at a 

refinery including flares that commence construction, reconstruction or modification after 

June 11, 1973, but on or before May 14, 2007. Subpart J applies to flares at petroleum 

refineries, where flares are defined as fuel gas combustion devices, and are limited to 

burning fuel gas for maintenance of the pilot flame if the fuel gas contains hydrogen sulfide 

(H2S) in excess of 0.10 gr/dscf. This limitation does not apply during process upsets, relief 

valve leakage, or other emergency malfunctions, where vent gases or fuel gas are released 

to the flare. This subpart also requires that a continuous monitoring and recording device 

be installed to track emissions of SO2 or H2S from the flare, in addition to the installation of 

an oxygen monitor for correcting the emissions data for excess air. 

Amendments to Subpart J add a new paragraph to 40 CFR 60.100 to allow sources affected 

by 40 CFR part 60, subpart J to comply by following the requirements in 40 CFR part 60, 

subpart Ja. Other amendments were administrative in nature and provided additional 

clarity to existing standards. 

 

17 40 CFR 60, subpart OOOO http://www.ecfr.gov/cgibin/retrieveECFR?gp=&SID=5c050fac63d930ea5bc5c11716888545&r=SUBPART&n=40y7.0.1.1.1.102 
Rule 4311 (Flares) Further Study 

September 16, 2014 

30 Regulatory Evaluation | SJVUAPCD 

Further Study Commitment: 

Evaluate New NSPS Requirements for Flares 

40 CFR 60 Subpart Ja 

NSPS for petroleum refineries (40 CFR 60, subpart Ja) apply to flares that commence 

construction, reconstruction or modification after June 24, 2008, and other affected 

facilities at petroleum refineries that commence construction, reconstruction, or 

modification after May 14, 2007. Subpart Ja contains requirements for monitoring systems 

for certain flares, but does not specify any emission limits or technology requirements. 

EPA amended 40 CFR 60 Subpart Ja on September 12, 201218. Amendments clarified 

existing requirements and applicability including what is considered and what is not 

considered a flare modification, clarification of secondary flares, and of the records that 

must be maintained by the operator. 

The September 2012 amendments to Subpart Ja included new requirements for flarerelated unit and process descriptions, assessments and evaluations, analyses of causes and 

corrective actions for reportable flaring events, and sulfur limits for petroleum refineries. 

The NSPS subpart Ja does not implement more stringent requirements than Rule 4311. 

While there may be some minor differences in terminology or requirements, making direct 

comparisons is not possible. The same level of controls and emission reductions are 

achieved through District regulations as through this NSPS. Additionally, as previously 

stated, the District’s Permit Services Department continuously evaluates NSPSs on a caseby-case basis to ensure the relevant flares comply with all federal requirements as they are 

promulgated. 

Subpart Ja has one new exemption for continuous monitoring which allows for fewer 

requirements, than previously required in the NSPS, and therefore, is not more stringent 

than current rule language. 

40 CFR 60 Subpart OOOO 

EPA finalized approval of a new NSPS requirement 40 CFR 60 Subpart OOOO on August 16, 

201219. This NSPS may indirectly affect some Valley flares since there is a possibility that a 

flare is exempt from the majority of Rule 4311 and is used as a control device for a vapor 

controlled tank that is subject to Subpart OOOO. 

Affected facilities under this subpart that may use flares as an approved control device 

include centrifugal compressors, storage vessels, and onshore natural gas processing 

 

18 77 FR 56422, http://www.gpo.gov/fdsys/pkg/FR-2012-09-12/pdf/2012-20866.pdf 

19 77 FR 49490, http://www.gpo.gov/fdsys/pkg/FR-2012-08-16/pdf/2012-16806.pdf
Rule 4311 (Flares) Further Study 

September 16, 2014 

31 Regulatory Evaluation | SJVUAPCD 

plants. If the facility chooses to meet the control requirements, then the flare must be 

designed and operated in accordance with §60.18(b) and must conduct the compliance 

determination using Method 22 at 40 CFR part 60, appendix A-7, to determine visible 

emissions. §60.18(b) was last amended Dec. 22, 2008, which is after the last amendment 

for District Rule 4311 (June 18, 2009). Therefore, Subpart OOOO has no new requirements 

for flares after Rule 4311 rule adoption. 

B. State Requirements 

There are no California state Air Resources Board (ARB) requirements specific to flaring 

activities in California because flares are located at stationary sources, and the emissions 

are therefore under the jurisdiction of California’s local air districts. 

C. Local Requirements at Other Air Districts 

As mentioned above, flares are under the jurisdiction of local regulatory agencies because 

they are located at stationary sources. In California, local regulatory agencies include air 

pollution control districts (APCD) and air quality management districts (AQMD). District 

Rule 4311 is unique from all other air districts’ flare rules in California in that it has a 

broader applicability. The Rule 4311 source category currently includes flares associated 

with oil and gas production, combustion, sewage treatment, incinerators, petroleum 

refining, and VOC control. Flare rules in other air districts in California are generally 

limited in applicability to flares at petroleum refining operations, or the use of flares at oil 

and gas or natural gas sources. As previously stated, EPA analysis of Rule 4311 resulted in 

the 2012 determination that Rule 4311 is as stringent as requirements in other air districts 

in California (76 FR 68106). 

The following is a brief summary of the regulatory comparisons, for the complete review of 

rule requirement comparisons, refer to the attachment (Rule Requirement Comparisons) at 

the end of this report. 

SCAQMD Rule 1118 (Emissions from Refinery Flares)20

SCAQMD adopted Rule 1118 (Emissions from Refinery Flares) in February of 1998. The 

emissions data collected as a product of Rule 1118, between 1999 and 2003, was analyzed 

and resulted in recommendations to further strengthen emissions monitoring and 

reporting procedures, which led to the adoption of amendments on November 4, 2005. 

The 2005 amendments prohibit the flaring of vent gases except in emergency situations, or 

during operational needs, including activities such as startups, shutdowns, and 

turnarounds. The 2005 amendments also established annual SO2 performance targets, the 

 

20 SCAQMD Rule 1118. Retrieved from https://www.aqmd.gov/rules/reg/reg11/r1118.pdf on 12/15/13. 
Rule 4311 (Flares) Further Study 

September 16, 2014 

32 Regulatory Evaluation | SJVUAPCD 

requirement that flares operate in a smokeless manner, and the requirement for annual 

inspections of pressure relief devices directly connected to flares. Any refinery that does 

not meet SO2 performance targets is required to have a FMP. The rule also contains 

provisions for refineries to give 24-hour advance notice for each large planned flaring 

activity, to notify SCAQMD within 1-hour of unexpected flaring events, and to submit 

quarterly reports detailing flow, emissions, and cause of each flaring event. 

EPA analysis of District Rule 4311 resulted in the 2012 determination that Rule 4311 is as 

stringent as requirements in SCAQMD Rule 1118, in terms of core RACT requirements21. 

Additionally, SCAQMD recently identified the need to evaluate flare emissions from sources 

other than refineries, sulfur recovery plants, and hydrogen production plants since District 

Rule 4311 regulates these flares and SCAQMD Rule 1118 does not.22

BAAQMD Regulation 12 Rule 11 (Flare Monitoring at Petroleum Refineries)23 and 

Regulation 12 Rule 12 (Flares at Petroleum Refineries)24 

On June 4, 2003, BAAQMD adopted Rule 12-11 (Flare Monitoring at Petroleum Refineries), 

which requires operators to monitor and record emissions data for flares at petroleum 

refineries. This rule facilitated the collection of emissions data from refineries and resulted 

in the adoption of Regulation 12 Rule 12. 

Regulation 12 Rule 12 (Rule 12-12) (Flares at Petroleum Refineries) was adopted on July 

20, 2005 to prohibit the use of refinery flares without the refinery first creating, following, 

and annually updating an FMP for each flare. Facilities are required to submit flaring 

reports when a flare at that facility releases more than 500,000 standard cubic feet of gas 

per calendar day (scf/day). The flaring report must identify the cause, take actions if 

possible to avoid future flaring from that cause, and explain actions that will be taken. The 

rule also requires continuous monitoring of the flare system’s knock-out drum water seal 

for leaks, and the submittal of annual reports to BAAQMD evaluating flaring events that 

released less than 500,000 scf/day, but emitted more than 500 lbs SO2. 

 

21 EPA TSD (Analysis of SJVUAPCD’s Rule 4311), http://www.regulations.gov/#!documentDetail;D=EPA-R09-

OAR-2011-0601-0022 

22SCAQMD (Board Meeting Date June 6, 2014 – Adopt the 2016 AQMP Reasonably Available Control 

Technology Demonstration). Retrieved from http://www.aqmd.gov/docs/defaultsource/Agendas/Governing-Board/2014/2014-jun6-031.pdf?sfvrsn=2 [Page 3 of RACT Demonstration, 13th 

page of the PDF]

23 BAAQMD Regulation 12 Rule 11. Retrieved from 

http://www.baaqmd.gov/~/media/Files/Planning%20and%20Research/Rules%20and%20Regs/reg%201

2/rg1211.ashx?la=en on 12/15/13. 

24 BAAQMD Regulation 12 Rule 12. Retrieved from 

http://www.baaqmd.gov/~/media/Files/Planning%20and%20Research/Rules%20and%20Regs/reg%201

2/rg1212.ashx?la=en on 12/15/13. 
Rule 4311 (Flares) Further Study 

September 16, 2014 

33 Regulatory Evaluation | SJVUAPCD 

EPA analysis of Rule 4311 resulted in the 2012 determination that Rule 4311 is as stringent 

as requirements in both BAAQMD flare rules in terms of core RACT requirements. 

VCAPCD Rule 54 (Sulfur Compounds)25 

VCAPCD Rule 54 (Sulfur Compounds) was adopted July 2, 1968, and last amended June 14, 

1994. Rule 54 has very limited applicability in that it is specific to sulfur compounds only. 

Rule 54 prohibits the discharge of sulfur compounds from any source, including flares that 

would exist as a liquid or gas at standard conditions in excess of the specified 

concentrations. Rule language also specifies several scenarios that are exempt from rule 

requirements including unplanned flaring, and planned flaring provided certain 

circumstances are met. Unplanned flaring is exempt from rule requirements as long as the 

unplanned burning of gas is for emergency or safety concerns. Planned Flaring Events are 

exempt from rule requirements provided specific conditions are met. Each operator is 

required to submit a Flaring Management Plan to the VCAPCD that includes descriptions of 

measures implemented to decrease flare gas volume and reduce sulfur emissions, planned 

operational or maintenance procedures that may cause flaring, design features of each flare 

system, and measures to be implemented to reduce the number of planned flaring events. 

EPA analysis of Rule 4311 resulted in the 2012 determination that Rule 4311 is as stringent 

as requirements in VCAPCD Rule 54 in terms of core RACT requirements. 

SBCAPCD Rule 359 (Flares and Thermal Oxidizers)26

SBCAPCD adopted Rule 359 (Flares and Thermal Oxidizers) on June 28, 1994. Provisions 

of this rule apply to the use of flares and thermal oxidizers at oil and gas production 

sources, petroleum refinery and related sources, and natural gas services. 

Rule 359 sets specific requirements for the sulfur content in gaseous fuels, technology 

based standards, flare minimization plans, emergency events, and emission and 

operational limits. 

Section D.3 of Rule 359 requires a FMP be submitted by any source subject to this rule that 

operates a flare rated at 15 MMBtu/hour or greater. For planned flaring, the FMP for all 

sources subject to this rule shall list a targeted maximum monthly flared gas volume, which 

shall not exceed 5% of the average monthly gas handled/produced/treated at the source 

unless the operator demonstrates such a maximum volume to be infeasible based on safety, 

engineering or cost constraints and proposes a different percentage. Any flaring that 

causes an exceedance of the emission limits or standards of Rule 359 shall not be a 

violation if the operator demonstrates that the exceedance resulted from an emergency 

event. 

 

25 VCAPCD Rule 54. Retrieved from http://www.vcapcd.org/Rulebook/Reg4/RULE%2054.pdf on 12/15/13. 

26 SBCAPCD Rule 359. Retrieved from http://www.sbcapcd.org/rules/download/rule359.pdf on 12/15/13. 
Rule 4311 (Flares) Further Study 

September 16, 2014 

34 Valley Flaring Compared to Other Air Districts | SJVUAPCD 

Rule 359 does not apply to the burning of sulfur compounds in the manufacturing of sulfur 

compounds. For oil and gas sources that recover sulfur as a by-product of gas 

treating/sweetening processes, the exemption for manufacturing shall apply to those 

specific processes (e.g., sulfur recovery plant). Additionally, flares whose flaring operations 

solely consist of planned, continuous flaring due to the non-availability of a produced gas 

pipeline outlet are exempt from FMP requirements. 

During the development of the District’s 2012 PM2.5 Plan and the 2013 Plan for the 

Revoked 1-Hour Ozone Standard, certain environmental interest groups claimed that 

District Rule 4311 was not as stringent as the SBCAPCD Rule 359, citing the specific flare 

minimization target of five percent of the total gas produced/handled/treated. However, 

the comments failed to point out the second part of the requirement that states that if an 

operator demonstrates such a maximum volume (5%) is infeasible due to engineering, 

safety, or cost constraints, the facility could obtain approval of a higher percentage. The 

District performed a thorough analysis of flare rules in other air districts in California 

during the development of the two plans, and during the rule amendment project in 2009. 

The District found that while the SBCAPCD rule appears to include a performance standard 

restricting the use of flaring, it actually allows flaring under broad conditions, and Rule 

4311 is at least as stringent. EPA concurs with this assessment as illustrated by the 

approval of the rule as a SIP revision in 201127. Therefore, EPA analysis of Rule 4311 

resulted in the 2012 determination that Rule 4311 is as stringent as requirements in 

SBCAPCD Rule 359 in terms of core RACT requirements. 

X. VALLEY FLARING COMPARED TO OTHER AIR DISTRICTS 

The following discussion compares Valley flares to flares regulated by other air districts in 

California. Major differences include the types of facilities operating the flares, the 

capacities of the flares, and the emissions from the flares. 

A. Operations and Capacities 

One major difference between Valley flares and flares regulated in other air districts is the 

type of facility that employs them. Rule 4311 regulates flaring from a variety of sources, as 

discussed in Section IV above (Valley Flares). Facility types include wastewater treatment, 

oil and natural gas production and processing, cheese and wine production, flat glass 

manufacturing, dairy operations, and a correctional facility. In contrast, flares regulated by 

SCAQMD, BAAQMD, VCAPCD, and SBCAPCD are employed only at oil and natural gas 

production and processing facilities. Because over 88% of flares in the Valley are operated 

 

27 76 FR 68106, http://www.gpo.gov/fdsys/pkg/FR-2011-11-03/pdf/2011-28391.pdf
Rule 4311 (Flares) Further Study 

September 16, 2014 

35 Valley Flaring Compared to Other Air Districts | SJVUAPCD 

at oil and natural gas production facilities as well, it is useful to compare these facilities 

between districts. 

Flares in the Valley and other air districts are primarily engineered for emergency 

operation during process upsets and emergency situations. While they can be used during 

maintenance, new equipment installations, and startup/shut-down, the main concern is 

safety. In this regard, Valley flares are similar to those in other districts, the difference 

being that the facilities in SCAQMD, BAAQMD, and SBCAPCD are much larger. The facilities 

in those districts are mostly operated at massive oil and gas refineries, with significantly 

higher throughputs than those in the Valley. Temperatures and pressures are higher, 

cracking regularly occurs, and flares must be engineering to control emergencies and 

process upsets on a larger scale. Flare gas is typically sent to a flare header, where it is 

distributed to multiple large flares. The flares at these facilities are much larger in physical 

size, as well as capacity, as shown in the table below. 

Table 6 Flaring Capacity Comparisons (MMBtu/hr) 

Air District Total Flares Median Mean Largest 

District 235 33 663 40,000 

SCAQMD 29 10,234 14,328 72,751 

BAAQMD 23 108 14,442 246,612 

VCAPCD 55 34 284 7,100 

SBCAPCD 75 17 1,242 18,200 

Flaring capacities of the flares in the SCAQMD, BAAQMD, and SBCAPCD are all significantly 

higher than the flaring capacities of flares in the Valley, while those in VCAPCD are similar 

size to Valley flares. Flares in BAAQMD have a wide range of capacities, while those in 

SCAQMD are all greater than 1,000 MMBtu/hr. Figure 6 shows the average capacity of 

flares in the District, SCAQMD, BAAQMD, VCAPCD, and SBCAPCD. 
Rule 4311 (Flares) Further Study 

September 16, 2014 

36 Valley Flaring Compared to Other Air Districts | SJVUAPCD 

Figure 6 Average Flare Capacities in the Different Air Districts 

The size and capacity of flares in other districts explains why the San Joaquin Valley Air 

District with roughly ten times the number of flares has NOx emissions nearly two times 

lower than BAAQMD and three times lower than SCAQMD, as illustrated in the emission 

inventory tables below. 

B. Comparison of Emission Inventories 

The flaring data in the tables below is from all flaring activities in each air district’s 

jurisdiction and is provided in the ARB-maintained 2012 CEPAM: NORCAL 2012 PM2.5 SIP 

Baseline Emission Projection Tool. 

0

2000

4000

6000

8000

10000

12000

14000

16000

District

SBCAPCD VCAPCD

SCAQMD

BAAQMD

Mean Capacity (MMBtu/hr)
Rule 4311 (Flares) Further Study 

September 16, 2014 

37 Conclusion | SJVUAPCD 

Table 7 NOx Emission Inventories (tons per day) 

 Air 

District 2012 2013 2014 2015 2016 2017 2018 2019

SJVAPCD 0.38 0.39 0.39 0.39 0.39 0.39 0.39 0.39 

SCAQMD 1.19 1.20 1.20 1.21 1.22 1.22 1.23 1.23 

BAAQMD 0.64 0.64 0.64 0.64 0.64 0.64 0.64 0.65 

VCAPCD 0.12 0.12 0.12 0.12 0.12 0.13 0.13 0.13 

SBCAPCD 0.09 0.09 0.09 0.08 0.08 0.08 0.08 0.08 

Table 8 VOC Emission Inventories (tons per day) 

Air 

District 2012 2013 2014 2015 2016 2017 2018 2019

SJVAPCD 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 

SCAQMD 0.40 0.41 0.41 0.41 0.41 0.41 0.41 0.41 

BAAQMD 1.32 1.33 1.33 1.33 1.33 1.33 1.33 1.33 

VCAPCD 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 

SBCAPCD 0.06 0.06 0.05 0.05 0.05 0.05 0.05 0.05 

Table 9 SOx Emission Inventories (tons per day) 

Air 

District 2012 2013 2014 2015 2016 2017 2018 2019

SJVAPCD 0.25 0.26 0.26 0.26 0.26 0.26 0.26 0.27 

SCAQMD 3.27 3.27 3.27 3.27 3.28 3.28 3.28 3.28 

BAAQMD 0.58 0.58 0.58 0.58 0.58 0.58 0.58 0.58 

VCAPCD 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 

SBCAPCD 0.18 0.17 0.17 0.17 0.16 0.16 0.16 0.15 

In summary, emissions in SCAQMD, BAAQMD, and SBCAPCD are much higher per flare than 

in the Valley. Far less volume is flared at Valley facilities, and each facility contributes only 

a small fraction of emissions. Emissions are effectively controlled at these facilities, and the 

remaining flaring activity is necessary for safety. Consequently, these facilities cannot 

reasonably be expected to further reduce flaring. 

XI. CONCLUSION 

District Rule 4311 limits the emissions from flaring activities while offering flexibility to 

affected industries by allowing a variety of options to control emissions. Flaring is itself is a 

highly effective control technology with a 98 percent or greater destruction efficiency. 
Rule 4311 (Flares) Further Study 

September 16, 2014 

38 Conclusion | SJVUAPCD 

Additionally, flares are necessary for safety during unforeseeable and unpreventable 

emergency situations. Any unreasonable restrictions on flaring have the potential to result 

in catastrophic consequences which may lead to explosions and other dangers. 

This further study report was committed to as a part of the District’s 2012 and 2013 

attainment plans to allow the District sufficient time to review and analyze information 

submitted to the District by operators of flares in July 2012 pursuant to Rule 4311 

requirements. Specifically, the District committed to evaluate FMPs, data from annual 

monitoring reports, reportable flaring event data, and two new NSPS requirements 

promulgated by EPA in 2012. 

This thorough and comprehensive further study evaluation has resulted in the District’s 

conclusion that operators of flares in the Valley are doing their due diligence to reduce 

emissions from flaring in the Valley by implementing alternatives to flaring and committing 

to perform activities to reduce flaring. As such, the District recommends no rulemaking 

action for Rule 4311. 

 
Rule 4311 (Flares) Further Study 

September 16, 2014 

39 Conclusion | SJVUAPCD 

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Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-1 Rule Requirement Comparisons | SJVUAPCD 

Attachment 

Rule Requirement Comparisons 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

DATES OF ADOPTION/ AMENDMENT 

Adopted Jun 20, 2002; 

Amended Jun 15, 

2006; Jun 18, 2009 

Adopted Feb 13, 1998; 

Amended Nov 4, 2005 Adopted Jun 4, 2003 Adopted Jul 20, 2005 

Adopted Jul, 1968; 

Revised Oct 1968; Jun 

1969; May 1972; Jul 

1983; Jun 1994 

APPLICABILITY 

All flares 

Flares used at: 

• Petroleum (petro.) 

refineries 

• Sulfur recovery 

plants 

• Hydrogen production 

plants 

Flares used at petro. 

refineries 

Flares used at petro. 

refineries 

Any person who 

discharges sulfur 

compounds from any 

source 

EXEMPTIONS 

• Municipal solid waste 

landfill flares subject to Rule 4642 

• Flares subject to 40 

CFR 60 WWW or Cc 

• Stationary sources 

w/ potential to emit <10 tons VOC and <10 tons NOx per 

Exempt from sampling and analyses for higher heating values and sulfur concentration for flare event that: 

• Results from 

catastrophic event 

• Is safety hazard to 

sampling personnel; 

Flares and thermal oxidizers used for: 

• Emissions from 

organic liquid storage vessels (subj. to R. 8-5) 

• Emissions from 

loading racks (subj. to R. 8-6, 8-33, or 8-39) 

Same as Rule 11 

(except last exemption 

on list) 

Sulfur emission limit and avg. concentration limit don’t apply to: Unplanned flaring for emergency or safety if: 

• Not result of 

intentional or negligent act, omission, improper 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-2 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

year(Not exempt from recordkeeping)

Sulfur dioxide (SO2) 

emissions (emissions) from flaring events caused by: 

• External power 

curtailment beyond operator’s control 

• Natural disasters • Acts of war or 

terrorism 

(Not exempt from flare monitoring system requirements) 

• Emissions from 

marine vessel loading terminals (subj. to R. 8-44) 

Thermal oxidizers used for: 

• Emissions from 

wastewater treatment systems (subj. to R. 8-8) 

• Emissions from pump 

seals (subj. to R. 8-18) (except when emissions from pump are routed to flare header) 

Monitoring and reporting total hydrocarbon (HC) or methane composition doesn’t apply to flare that burns flexicoker gas if weekly sampling shows methane/nonmethane content of vent gas flared is <2%/<1% by volume 

maintenance or setting of shut-in sensors 

• Results from 

operational problems (emergency blowdowns, process upsets, power outages, equipment breakdown) 

• Records of event kept • corrective measures 

immediately taken 

• Event lasts <24 hr. • Notify <4 hr. after 

detection and submit report if event >1 hr. 

Planned flaring if: 

• Notice submitted >72 

hr. in advance, justifying work (reasons and steps to minimize sulfur emissions) 

• Notice can be 

submitted <72 hr. if hazardous situation, economic harm, or excess emissions 

• Submit planned 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-3 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

flaring mgmt. plan 

• Records kept 2 yrs. • District notified when 

work complete 

• Sulfur emissions are 

minimized 

• Excess emissions fee 

paid to District each year ($5.00/lb. SO2 emitted) 

FLARE MINIMIZATION PLAN (FMP) REQUIREMENTS 

FMP requirements don’t apply if flaring caused by emergency and necessary to prevent accident, hazard or release of vent gas directly to the atmosphere FMP required for petro. refinery flare or any flare w/ capacity >5.0 MMBtu/hr.: 

• Technical specs for 

each flare, knock-out 

Owner/operator of petro. refinery exceeding performance targets submit FMP: 

• <90 days from end of 

year w/ emissions exceeding target 

• Plan is pursuant to 

Rule 221 and fees pursuant to Rule 306 

• List all actions to be 

taken to meet targets: 

o Technical specs for 

flares, knock-out 

None 

FMP required for flares subject to rule and 3-month status reports required until FMP completed: 

• Technical 

information for each flare 

• Upstream equipment 

and processes (Same as SJVAPCD and SCAQMD) 

• Equipment, 

processes, and procedures 

Each operator submits a planned flaring management plan: 

• Measures to decrease 

FG volume and reduce sulfur emissions 

• Description of 

planned operational or maintenance procedures that may cause flaring 

• Description of each 

flare system including design 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-4 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

pots, surge drum, water seal, and flare gas (FG) recovery system 

• Process flow 

diagrams of upstream equipment and process units venting to each flare 

• Equipment, 

processes, or procedures planned to install or implement to minimize flaring and planned date 

• Evaluations of 

preventative measures to reduce flaring expected due to planned major maintenance activities, gas quantity and quality issues, and recurrent failure of equipment or processes 

• Submit updated FMP 

every 5 years and for new or modified equipment prior to 

pots, surge drums, water seals and FG recovery systems 

o Process flow 

diagrams of upstream equipment and process units venting to flares 

o Policies, 

procedures, and equipment improvements to minimize flaring and flare emissions 

o FG recovery 

equipment and treatment systems to be installed 

• FMPs available for 

60-day public review prior to approval 

• 45 days allowed to 

correct deficiencies 

• Facility in violation if 

FMP denied 

• Revised FMP 

submitted 90 days after end of year if performance targets exceeded 

implemented in last 5 years to reduce flaring and those planned to be installed or implemented 

• Prevention measures, 

including schedule for implementation for flaring: 

o That has or will 

occur during planned major maintenance 

o Expected to occur 

due to issues of gas quantity and quality (include audits of capacities), or caused by recurrent failure of equipment or processes 

features 

• Description of any 

sulfur reduction system 

• Measures to be 

implemented to reduce the number of planned flaring events 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-5 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

installing 

ANNUAL MONITORING REPORTS 

For refinery flare or flare w/ flaring capacity >50 MMBtu/hr: Operator submit annual report 

Submit quarterly report <30 days after 

end of each quarter including: 

• Information required 

Monthly report: 

• Total volumetric flow 

each day and month 

• If gas composition 

monitored w/ 

None None 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-6 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

<30 days after end of each 12 month period including: 

• Total volumetric flow 

of vent gas (scf) for each day 

• Contents of vent gas 

composition: 

o Hydrogen sulfide 

o Methane 

o HC 

• If vent gas 

composition monitored by continuous analyzer or analyzers: the following for each hour of the month: 

o Avg. total HC 

content by volume 

o Avg. methane 

content by volume 

o Total reduced sulfur 

content by volume or hydrogen sulfide content by volume 

• Avg. molecular 

weight for each hour of each month (if measured) 

• For pilot and purge 

to be monitored: 

o Table of nine 

operating parameters, based on flare type (clean service, emergency service, general service) 

o Alternative flare 

vent gas sampling information necessary to calculate flare emissions 

o Flare monitoring 

system data 

o Images of visible 

emissions 

o Presence of pilot 

flame 

o Pilot gas and purge 

gas flow to each flare 

• Total daily and 

quarterly emissions of criteria pollutants from each flare and each flare event along with information used to calculate emissions 

sampling, content by volume for each sample of total HC, methane, and H2S 

• If composition 

monitored w/ continuous analyzer, avg. content by volume of: total HC; methane; total reduced sulfur; H2S 

• Avg. molecular 

weight for each hour of the month (if measured) 

• For pilot & purge gas 

o Type of gas 

o Volumetric flow for 

each day and month 

o Means used to 

determine flow 

• For any 24-hr period 

when 1 million scf flared, description: 

o Cause o Time and duration o Source 

o Measures to reduce 

or eliminate flaring 

• Monitoring system 

downtime periods 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-7 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

gas: 

o Type of gas used 

o Volumetric flow for 

each day and each month 

o Means used to 

determine flow 

• Flare monitoring 

system downtime 

• SO2 emissions for 

each day and each month 

• Flow verification 

report for each flare 

• Description of cause 

and category of each flare event 

• Records of annual 

acoustical or temperature leak survey 

• Flare monitoring 

system downtime periods 

• Copy of written 

notices for all reportable air releases related to any flare event 

• Images recorded for 

the month 

• Methane, nonmethane, and SO2

emissions for each day and for the month 

Semi-annual flow verification report, comparing flow measured by monitoring system and flow verification for same period of time 

REPORTABLE FLARING EVENT REPORTS

• Definition: 

o Flaring event where 

>500,000 scf gas flared/day or 

o SO2 emissions >500 

lb/day 

o Ends when water 

seal integrity demonstrated or 

o For flares w/o 

water seal, ends when flow <0.12 ft/s 

• Submit annual report 

summarizing all 

Requirements: 

• Notify by telephone 

<1 hr. of unplanned 

flare event w/ emissions >100 lb. VOC, >500 lb. SO2, or >500,000 scf gas 

• Submit Specific Cause 

Analysis w/in 30 days – cause, duration, mitigation/ corrective actions 

For any 24-hour period during which >1 million scf of vent gas was flared: 

• Cause • Time of occurrence 

and duration 

• Source or equipment 

of origin 

• Measures taken to 

reduce or eliminate flaring 

Notify if volume flared >500,000 scf per day: 

• Results of cause 

investigation 

• Measures to prevent 

recurrence 

• Justification for 

rejecting measures 

• Explanation why 

consistent with FMP 

• Explanation of why 

emergency and cannot be recovered 

• Volume flared 

For unplanned flaring >1 hr. in duration: 

• Notify <4hr. after 

detection 

• Submit report: 

o Date, time, duration, 

volume of gas flared 

o Reasons for flaring o Settings pressure 

relief valves and max/min allowed safety settings 

o Corrective 

measures and actions to prevent 
Rule 4311 (Flares) Further Study 

September 16, 2014 

 A-8 Rule Requirement Comparisons | SJVUAPCD 

District Rule 4311 

(Flares) 

SCAQMD Rule 1118 

(Control of Emissions 

from Refinery 

Flares) 

BAAQMD Reg. 12 

Rule 11 (Flare 

Monitoring at 

Petroleum 

Refineries) 

BAAQMD Reg. 12 

Rule 12 (Flares at 

Petroleum 

Refineries) 

VCAPCD Rule 54 

(Sulfur Compounds) 

reportable flaring events: 

o Results of cause 

investigation 

o Mitigation/ 

corrective actions to prevent recurrence 

o Justification for 

rejecting measures 

o Explanation of why 

emergency and cannot be recovered

o Date, time, duration 

• Methane, nonmethane, HC, and SO2

emissions 

recurrence 

o Sulfur emissions o Equipment or 

controls that failed 

For planned flaring: 

• Notice submitted >72 

hr. prior: 

o Work that requires o Date and time o Expected gas 

volume and sulfur emissions 

o Steps or equipment 

to minimize sulfur emissions