i

December 3, 2015 

Project Team 

Jesse Madsen, Air Quality Specialist II 

Dave Torii, Air Quality Engineer II 

Steve Leonard, Senior Air Quality Engineer 

Chay Thao, Program Manager 

Errol Villegas, Permit Services Manager 

Leonard Scandura, Permit Services Manager 

Sheraz Gill, Director of Strategies and Incentives

Draft Further Study 

Rule 4311 Flare Minimization Plans 

2015 
DRAFT Further Study – Rule 4311 Flare Minimization Plan 

December 3, 2015 

i Table of Contents | SJVUAPCD 

Table of Contents 

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

II. Background .............................................................................................................. 2

III. What is Flaring? ........................................................................................................ 6

A. General Equipment Description ............................................................................. 6

B. General Process Description ................................................................................. 7

IV. Flaring in the San Joaquin Valley ............................................................................. 8

V. Flare Minimization Plans ........................................................................................ 10

A. Rule 4311 Flare Minimization Plan (FMP) Requirements .................................... 10

B. Flare Minimization Practices ................................................................................ 11

VI. Flare Control Technology Evaluation ...................................................................... 16

VII. Further Study Findings and Recommendations...................................................... 16
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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). The San Joaquin Valley Air Pollution Control District 

(District) must explore all available emission reduction opportunities in order to 

demonstrate attainment for multiple federal ozone and PM2.5 standards in the coming 

years. In an effort to leave no stone unturned, in its 2015 Plan for the 1997 PM2.5 

Standard (2015 PM2.5 Plan), the District committed to a further study to review submitted 

Flare Minimization Plans (FMPs) under District Rule 4311 (Flares) and identify the most 

effective flare minimization practices utilized by operators. As a result of this 

comprehensive study the District offers the following findings and recommendations: 

1. The District identified minimization practices currently performed at 

facilities that have the potential to be applied to other facilities. 

a. The District recommends conducting a thorough evaluation of the 

most effective flare minimization practices included in approved 

FMPs and requiring the implementation of these practices where 

technologically achievable and economically feasible. Even though 

operators of flares in the Valley have already taken extensive measures to 

reduce flaring, through this study the District has identified effective 

minimization practices currently performed at some facilities that could be 

employed at other facilities to further reduce flaring. To further evaluate 

opportunities for emission reductions from flaring, the District will perform 

an exhaustive evaluation of these flare minimization practices in its 

upcoming 2016 ozone and PM2.5 attainment plans and propose potential 

rule amendments requiring the use of these practices where 

technologically achievable and economically feasible. 

b. The District recommends exploring options to further promote the 

implementation of the most effective flare minimization practices 

during the FMP submittal and review process. Under Rule 4311, 

FMPs are required to be submitted and approved for existing, new, and 

modified flaring systems. For existing systems, an updated FMP is 

required to be submitted and approved every five years. Working with 

operators to identify potential flare minimization practices during the FMP 

review process provides operators the opportunity to incorporate feasible 

flare minimization practices when new and modified systems are proposed 

and during the ongoing review of FMPs. 

 
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2. Ultra low NOx technologies with the potential to further reduce emissions 

from flaring have recently become available. The District recommends 

conducting a thorough evaluation of new ultra low NOx control 

technologies for flaring and requiring the implementation of these 

technologies where technologically achievable and economically feasible. 

Through this further study, the District has identified new low NOx control 

technologies that may serve as suitable options for further reducing NOx 

emissions from flaring in the San Joaquin Valley. To further evaluate 

opportunities for emission reductions from flaring, the District will perform an 

exhaustive evaluation of NOx emission reduction control technologies in its 

upcoming 2016 ozone and PM2.5 attainment plans and propose potential rule 

amendments requiring the use of these technologies where technologically 

achievable and economically feasible. 

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 a further study 

measure. Furthermore, the District also committed to this further study in the District’s 

2013 Plan for the Revoked 1-Hour Ozone Standard.

To satisfy these commitments, the District completed and published the Rule 4311 

(Flares) Further Study report on September 16, 2014 (2014 Study).1

 In that study, District 

staff reviewed the 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 flaring. In addition to the review 

committed 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 that extensive effort, 

the District made the following findings: 

1. Flare Emissions Comprise a Small Percentage of the Overall NOx 

Emissions in the Valley 

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

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

 

1

 SJVAPCD. (2014) Rule 4311 (Flares) Further Study 2014. Retrieved from 

http://www.valleyair.org/Air_Quality_Plans/docs/R4311.pdf. 
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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 

properly.2

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

District analysis 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 Effective 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. Annual monitoring reports are submitted from a variety of 

industries including, but not limited to, oil and gas production, wastewater 

treatment, and wine and cheese making. 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. 

 

 

2

 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. 
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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. 

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. 

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. 
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7. Rule 4311 Requirements are more stringent than 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. 

In the 2014 Study, the District concluded that operators of flares in the Valley were subject 

to the most stringent emission requirements and were proactively implementing 

alternatives and committing to activities that reduce flaring. Based on that conclusion, the 

District recommended no rulemaking action for Rule 4311 at that time. 

On April 16, 2015, the District’s Governing Board adopted the 2015 Plan for the 1997 

PM2.5 Standard (2015 PM2.5 Plan)

3

. As demonstrated in the District’s 2015 PM2.5 Plan, 

Rule 4311 already meets the Environmental Protection Agency’s (EPA) Best Available 

Control Measures (BACM) and Most Stringent Measure (MSM) requirements. In fact, 

EPA approved Rule 4311 as satisfying all applicable federal requirements on November 3, 

2011.4

 However, due to the need to demonstrate attainment for multiple federal ozone 

and PM2.5 standards in the coming years and the need to search for all available 

emissions reductions, the District committed to undertaking a comprehensive review of 

FMPs submitted under Rule 4311, publish a draft report for public review and commenting 

by December 1, 2015, and finalize the report by March 31, 2016 after receiving input from 

flare operators and addressing public comments. This further study includes the following 

elements: 

1. Review submitted FMPs to identify the most effective flare minimization 

practices utilized by operators to reduce flaring in various source categories and 

applications. Upon completion of review, work closely with affected operators to 

evaluate and implement, when feasible, the most effective flare minimization 

practices through the FMP submittal and approval process under Rule 4311. 

2. Evaluate the technological achievability and economic feasibility of 

implementing new/additional minimization practices or technologies at affected 

facilities. 

 

3

 SJVAPCD. (2015). 2015 Plan for the 1997 PM2.5 Standard. Retrieved from

http://www.valleyair.org/Air_Quality_Plans/PM25Plans2015.htm 

4

 EPA. 76 Federal Register 213, 68106-68107. 11/3/2011. http://www.gpo.gov/fdsys/pkg/FR-2011-11-

03/pdf/2011-28391.pdf 
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III. WHAT IS FLARING? 

Flares serve two basic functions: 1) as an emission control device for VOC emissions, 

and/or 2) 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 nonassisted). 

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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Figure 1. Flare Diagram5

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 

 

5

 EPA. (1995). 13.5 Industrial Flares. Retrieved from 

http://www.epa.gov/ttnchie1/ap42/ch13/final/c13s05.pdf 
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the base 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. 

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. 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. FLARING IN THE SAN JOAQUIN VALLEY 

The information in this section is based on data analysis from the District’s Rule 4311 

(Flares) Further Study report published on September 16, 2014.6 

 

6

 SJVAPCD. (2014) Rule 4311 (Flares) Further Study 2014. Retrieved from 

http://www.valleyair.org/Air_Quality_Plans/docs/R4311.pdf. 
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There are 235 flares in the Valley subject to Rule 4311 requirements. Of those 235 

flares, 126 are exempt (except for recordkeeping requirements) 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 operated at stationary sources with the potential to emit for all 

processes of less than 10 tons per year of VOC and less than 10 tons per year of NOx. 

However, all new or modified flares are subject to New Source Review (NSR) 

requirements including Best Available Control Technology (BACT), 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. 

 

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

requirements. 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. 

Flares subject to Rule 4311 requirements in the Valley are utilized by a diverse group of 

industries as illustrated by Table 1 below. 

Table 1. Facility Types for Flares that Submitted FMPs 

Facility Type # of Flares

Oil and Gas Production 68 

Petroleum Refining 7 

Natural Gas Processing 6 

Natural Gas Transmission 2 

Wastewater Treatment (Wastewater Treatment Plants, Cheese 

Production, Wineries, Dairy, Beef Packer) 10 

Miscellaneous (Correctional Facility, Flat Glass Manufacturer) 2 

Total 95 

The majority of the Valley flares are standby or emergency flares. Standby flares are 

only utilized intermittently to dispose of gas during maintenance or periods when gas is 

in excess of steady state gas collection system capacity, and are not used as a method 

of primary disposal for collected gases. Emergency flares are only used during 

emergency events, 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. 
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Of the 95 facilities subject to FMP requirements, 92 are permitted for standby or 

emergency use, while only 3 are permitted as primary disposal devices. 

Due to their limited use, flares are currently a small contributor to overall Valley 

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

of the total annual NOx and 0.17% of total annual PM2.5 emitted from all stationary, 

area, and mobile sources in 2012. 

V. 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. 

Pursuant to Section 6.5.1, FMPs submitted to the District are required to 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, identifying the type and location of all 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, 
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and scrubbing capacity available for vent gas for use as a fuel as well as 

determination of 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. This includes determination of adequacy of 

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

considered recurrent if it occurs more than twice during any five year period as a 

result of the same cause. 

B. Flare Minimization Practices 

District staff with extensive expertise in flare operations conducted a detailed review of 

all approved FMPs to identify the variety of flare minimization practices used by affected 

facilities. In addition, District staff also worked closely with affected facilities to gain 

more in-depth understanding of the minimization practices. 

In reviewing the FMPs, the District found a variety of flare minimization practices 

specific to each facility that could potentially be employed at other facilities to further 

reduce flaring at their operations. These practices may not only serve to reduce flaring 

activities and associated emissions but may also provide economic, safety, and other 

benefits to affected facilities. Because of the unique nature of each facility, the 

technological achievability and economic feasibility of transferring these minimization 

practices or technologies from one facility to another will require further analysis. 

A description of effective flare minimization practices identified in approved FMPs is 

presented below: 

Alternatives to Flaring 

One way to prevent flaring is to capture the gas and utilize it for some beneficial 

purpose as flaring can be a waste of a precious resource. The following alternative 

uses for flare gas were identified in submitted FMPs to minimize flaring. 

• Use gas as a fuel for equipment rather than flaring. Capturing gas and routing it 

into a fuel gas system to power various processes is a great means of utilizing gas 

that would otherwise be flared. There is a financial incentive to utilize this practice to 

the greatest extent feasible across all facility types as the gas can be used to 

supplement, or in some cases even completely supply, the process energy needed, 

(i.e. IC engines) to produce electricity, and boilers for steam generation and process 

heating. 
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There are several barriers with implementing this practice. Some facilities do not 

have a use for combustion equipment on-site. For those that do have a use for the 

combustion equipment, it may not be economically feasible to purchase, install and 

operate such equipment, the multiple stages of treatment equipment to make the 

gas suitable for use at the facility, and the infrastructure required to connect process 

streams and utilities to the fuel gas system. Additionally, the installation of extra 

equipment to handle the waste gas can potentially add more complexity to the 

maintenance and testing, and can increase the number of potential points of failure. 

• Injection of oil field gas into DOGGR-approved disposal wells. Reinjection of 

gas into subsurface geologic formations disposal wells is a potential alternative to 

flaring. These wells are regulated by the California Department of Conservation, 

Division of Oil, Gas and Geothermal Resources (DOGGR). However, the permits for 

these wells can be extremely difficult to obtain from the state, and require significant 

capital investment to complete the various studies and installation of infrastructure in 

California. Additionally, the permits place a limit on volume reinjected that if 

exceeded requires the facility to dispose of gas by other means. 

• Send oilfield gas to a sales gas line. Gas that is of high enough quality (i.e. high 

energy content, low sulfur or nitrogen content) can be sold through a sales gas line. 

There can be many barriers associated with this alternative including proximity to an 

existing gas line, quantity and quality of gas generated, and the economics of 

purchasing, installing, and maintaining a new sales gas line and all the associated 

treatment and transmission equipment and infrastructure. 

Maintenance and Testing 

A proactive and preventative maintenance and testing program can greatly reduce 

flaring by minimizing downtime from equipment failure. Furthermore, testing helps 

predict potential equipment failure and provides an opportunity to coordinate 

repair/replacement in a way that reduces flaring. If failures occur unexpectedly, the 

equipment may need to be taken offline immediately, requiring gas to be routed to flares 

to prevent an unsafe situation. The following maintenance and testing practices were 

identified in submitted FMPs to minimize flaring. 

• Implement a preventative maintenance program to predict failure in pipelines 

and stationary equipment (measure corrosion). The gas going through pipelines 

and stationary equipment can be very corrosive. A predictive method such as using 

x-rays to measure pipe thickness is used to determine when to replace the 

equipment. This testing is performed on a periodic basis as dictated by the 

equipment type and the service it is in. 
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• Install high-pressure alarms on process vessels. Installation of alarms on 

process vessels can indicate a high pressure build-up (before pressure relief valves 

opens and directs gasses to flares) so that operators can intervene before flaring 

occurs.

• Inspect pressure relief valves routinely to ensure proper operation. If a 

pressure relief valve improperly seats or is otherwise defective, gases will leak and 

be combusted in the flare. In an attempt to reduce such occurrences, the pressure 

relief valves can be inspected periodically.

• Maintain and calibrate flare gas control valves on a routine schedule. Flare 

gas lines are typically equipped with control valves to regulate the volume of gas 

going to flares. Should these valves malfunction, it is possible that excessive gas 

would be directed to the flare. These valves could be calibrated on a routine 

schedule. 

• Retain spare parts onsite to minimize system downtime. Quick and easy access 

to spare parts reduces equipment downtime and associated flaring. While the 

economic feasibility of purchasing and maintaining backup equipment will need to be 

considered on a case-by-case basis for each facility, some facilities maintained the 

following types of equipment onsite to minimize flaring: 

o Compressors. Compressors are ubiquitous in the gas and petroleum 

industry and play a critical role in many different stages of oil and gas 

production, processing/refining, and transmission. 

o Sulfur scrubber components/media. If the sulfur scrubber system is down, 

the fuel cannot be processed for onsite use and must be flared instead. 

o Spare parts for primary combustion equipment (blowers, etc.). If the 

primary combustion equipment is down, the fuel cannot be utilized onsite and 

must be flared instead. 

Procedures to Reduce Flaring during Maintenance and Shutdowns 

Another effective flare minimization measure is to optimize and coordinate maintenance 

activities so that equipment failure and downtime is minimized to the extent feasible. A 

proactive and preventative maintenance program can greatly reduce downtime and 

thereby minimize flaring. However, during maintenance and shutdown events, 

operators can take additional measures to avoid or reduce flaring. The following 

procedures were identified in submitted FMPs. 
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• Perform maintenance on one area without impacting other operations on site. 

Designing a facility in a manner that allows maintenance to be performed in one 

area of a facility without affecting other operations can reduce flaring. This allows 

the other operations to continue normally without the need to flare excess gas. 

• Curtail oil/gas production during planned shutdown of sales line. In the event 

of a planned shutdown of a sales gas pipeline, and/or major maintenance activities, 

oil/gas production can be curtailed. This could potentially result in lost revenue. 

• Close oil well casing vents during vapor control system maintenance. Casing 

gas remains in reservoir instead of being flared, but this can potentially result in 

reduced oil production rate until vents are opened.

• Store gas in bladder tank. For waste water treatment plants, limited amounts of 

digester gas can be stored in bladder tanks during maintenance, testing, or process 

upsets and later be routed to combustion devices for beneficial use on-site. 

• Plan maintenance activities during optimal periods. Scheduling maintenance 

during periods of minimum capacity needs and/or following planned process unit 

shutdowns has the potential of minimizing flaring activities. 

• Optimize planned shutdowns for major maintenance. Most inspection, repair, 

and minor maintenance work can be performed while a facility is in operation. 

However, there are times when a facility has to shut down and flare process gas to 

conduct major maintenance work. The management of a facility shutdown is known 

as a “turnaround”. Scheduled facility shutdowns are expensive and labor intensive 

due to the loss of production and the expense of the turnaround itself. While 

turnaround procedures are primarily focused on minimizing downtime, the following 

specific procedures were identified in submitted FMPs to minimize flaring during 

plant turnaround. 

o Have extra personnel on site to re-start the plant as quickly as possible 

o Recycle discharge gas back to compressor inlets until minimum operating 

pressure is obtained 

o Prior to turnaround, identify critical equipment to be serviced to avoid refinery 

downtime and associated flaring 

o Phase equipment and process unit shutdowns to minimize fuel gas 

imbalances that may result in additional flaring 

o Identify alternate disposition of process gases to minimize flaring; 

o Identify key process unit operations such as fuel gas systems and sulfur 

recovery operations that must remain in operation to minimize flaring of 

sulfur-containing gases 

o Phase equipment and process unit start-ups to minimize start-up duration and 

the flaring associated with these transitional operations 
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Redundant Systems 

Even with the most rigorous and proactive maintenance programs in place, there is 

always the potential for critical equipment failure. Installing redundant systems 

minimizes the potential of downtime by allowing operators to quickly switch from one 

system to another in the event of equipment failure or during maintenance. The 

following redundant systems were identified in FMPs to minimize flaring. 

• Redundant compressors. Compressors can fail, and as a result the gas may 

need to be flared. Installation of a redundant secondary compressor can minimize 

flaring when the primary compressor is down. 

• Redundant gas treatment systems (sulfur scrubber). This allows gas to continue 

to be treated and burned in combustion equipment when one unit is not available. 

• Redundant digester gas-fired turbines. Some wastewater treatment plants have 

incorporated redundant digester-gas-fired turbines into their system design. The 

redundant system allows the turbines to be maintained without the need to flare. 

This has potential to reduce a considerable amount of flaring, as the turbines for 

these types of operations typically require frequent maintenance. In addition, a 

redundant system reduces downtime and extends the life of the turbines.

Procedures to Prevent or Mitigate the Effects of Power Outages to Reduce Flaring 

A power outage has the potential to result in flaring as vapors are sent to flares to 

protect the facility from being over-pressurized. The following specific procedures were 

identified in submitted FMPs to mitigate the effects of power outages and reduce flaring. 

• Backup generators. Install emergency IC engine/generators to power equipment 

during power outages. 

• Power outage alarm. Send alarms to all operators when power outage occurs to 

ensure rapid response. 

• Infrared testing. Implement infrared testing of electrical equipment on a routine 

basis to identify hot-spots that could result in a power outage.

• Avian guards. Install avian guarding in substations to deter birds from contacting 

energized equipment. 
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16 Flare Control Technology Evaluation | SJVUAPCD 

VI. FLARE CONTROL TECHNOLOGY EVALUATION 

As a component of this further study, the District evaluated the feasibility of new ultra 

low NOx flare emission control technologies. While the modernization of flare 

technology will not reduce the frequency or volume of flaring activities, it can reduce the 

emissions from such activities, thereby accomplishing the same end goal. 

The District has identified a new class of VOC destruction devices that are similar to 

enclosed flares but operate with mixing controls and are being put into practice in the 

petroleum industry as control devices. These devices offer ultra low NOx emissions of 

approximately 0.02 lb NOx/MMBtu (compared to existing District Rule 4311 requirement 

of 0.068 lb NOx/MMBtu). These devices may not considered flares by the Rule 4311 

definition, but are an alternative method for VOC control. One Permit to Operate and at 

least eight Authority to Construct permits have been issued to facilities in the Valley for 

these new devices. 

These new devices may not be a viable replacement for some emergency flares, 

particularly those with high intermittent gas volume capacity requirements. These 

devices appear suitable for use at sites with more predictable gas disposal needs. To 

further evaluate opportunities for emission reductions from flaring, the District will 

perform an exhaustive evaluation of NOx emission reduction control technologies in its 

upcoming 2016 ozone and PM2.5 attainment plans and propose potential rule 

amendments requiring the use of these technologies where technologically achievable 

and economically feasible. 

VII. FURTHER STUDY FINDINGS AND RECOMMENDATIONS 

As a result of this comprehensive study the District offers the following findings and 

recommendations: 

1. The District identified minimization practices currently performed at 

facilities that have the potential to be applied to other facilities. 

a. The District recommends conducting a thorough evaluation of the 

most effective flare minimization practices included in approved 

FMPs and requiring the implementation of these practices where 

technologically achievable and economically feasible. Even though 

operators of flares in the Valley have already taken extensive measures to 

reduce flaring, through this study the District has identified effective 

minimization practices currently performed at some facilities that could be 

employed at other facilities to further reduce flaring. To further evaluate 

opportunities for emission reductions from flaring, the District will perform 

an exhaustive evaluation of these flare minimization practices in its 
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17 Further Study Findings and Recommendations | SJVUAPCD 

upcoming 2016 ozone and PM2.5 attainment plans and propose potential 

rule amendments requiring the use of these practices where 

technologically achievable and economically feasible. 

b. The District recommends exploring options to further promote the 

implementation of the most effective flare minimization practices 

during the FMP submittal and review process. Under Rule 4311, 

FMPs are required to be submitted and approved for existing, new, and 

modified flaring systems. For existing systems, an updated FMP is 

required to be submitted and approved every five years. Working with 

operators to identify potential flare minimization practices during the FMP 

review process provides operators the opportunity to incorporate feasible 

flare minimization practices when new and modified systems are proposed 

and during the ongoing review of FMPs. 

2. Ultra low NOx technologies with the potential to further reduce emissions 

from flaring have recently become available. The District recommends 

conducting a thorough evaluation of new ultra low NOx control 

technologies for flaring and requiring the implementation of these 

technologies where technologically achievable and economically feasible. 

Through this further study, the District has identified new low NOx control 

technologies that may serve as suitable options for further reducing NOx 

emissions from flaring in the San Joaquin Valley. To further evaluate 

opportunities for emission reductions from flaring, the District will perform an 

exhaustive evaluation of NOx emission reduction control technologies in its 

upcoming 2016 ozone and PM2.5 attainment plans and propose potential rule 

amendments requiring the use of these technologies where technologically 

achievable and economically feasible. 

 
DRAFT Further Study – Rule 4311 Flare Minimization Plan 

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