Sour Non-Routine Flaring

FRAMEWORK

Sour Non-Routine Flaring

November 15th, 2013

Publication Number 2014-0006

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www.capp.ca [email protected]

The Canadian Association of Petroleum Producers (CAPP) represents 130

companies that explore for, develop and produce natural gas, natural gas liquids,

crude oil, oil sands, and elemental sulphur throughout Canada. CAPP member

companies produce more than 90 percent of Canada’s natural gas and crude oil.

CAPP also has 150 associate members that provide a wide range of services that

support the upstream crude oil and natural gas industry. Together, these members

and associate members are an important part of a $120-billion-a-year national

industry that affects the livelihoods of more than half a million Canadians.

Disclaimer

This publication was prepared for the Canadian Association of Petroleum

Producers (CAPP). While it is believed that the information contained herein is

reliable under the conditions and subject to the limitations set out, CAPP does

not guarantee its accuracy. The use of this report or any information contained

will be at the user’s sole risk, regardless of any fault or negligence of CAPP or

its co-funders.

http://www.capp.ca/

November 15, 2013 Non-Routine Flaring Framework Page ii

Overview

The document here within is supported by both industry and government. It is a

historical account of what has been seen in Alberta Environment and Sustainable

Resource Development’s modelling guidelines and section 7.12 in the Energy

Resources Conservation Board (ERCB) Directive 060 (D060). In 2004 a

partnership team between government and industry was formed to develop a

comprehensive management plan for non-routine flares. This team was named the

Non-routine Flaring Task Team (NRFTT).

Flaring can occur during routine and non-routine situations. Routine events occur

as a result of the normal operation of a facility or process while non-routine

events are considered as outside the normal operation of a facility. Non-routine

flaring occurs during events such as planned maintenance activities, and

unplanned upsets and emergencies, and are usually both infrequent and of short

duration.

Although a comprehensive flare management plan was deemed necessary to

address the compliance and enforcement of non-routine flaring, it was necessary

to find ways of simplifying this plan as much as possible in order to regulate it

practically. As such, to avoid confusion over what flare events are considered

upsets or emergencies, both of these flare events were grouped into unplanned

flare events.

Industry recognizes the importance of not exceeding Alberta Ambient Air Quality

Objectives (AAAQOs). Historically, regulatory dispersion modelling for

continuous sources were applied to non-routine flares and did not account for the

infrequent, short term nature of non-routine flaring events. The approach

proposed and supported by industry and government recognizes the distinction

between Risk Based Criteria modelling versus Risk Based Criteria observations.

The approach taken by the NRFTT is based on an equivalent level of risk and

reflects regulatory requirements. Monitored exceedances of the AAAQOs must be

reported and may be subject to enforcement action.

Prior to adopting the non-routine flaring management framework, air dispersion

modelling for non-routine flaring was performed assuming a continuous source

operating at all hours in the modelling period, which is usually a five year period

as outlined in Section 4. This is considered the correct modelling approach as

non-routine flaring includes unplanned events in which non-routine flaring could

take place at any time and regulators need to know the potential impacts that non-

routine flaring can cause under all possible meteorological conditions. The

problem with this approach is that up to now there has not been a way to address

the infrequent nature of these events. Prior to adopting the non-routine flaring

management framework, the way for determining compliance of non-routine

flares from an air dispersion modelling perspective was the same as a continuous

source or well test as outlined in Section 2.1. Essentially, it has been assumed that

non-routine flares operate continuously for compliance purposes.

November 15, 2013 Non-Routine Flaring Framework Page iii

Risk considers both the chance of a predicted exceedance of the AAAQOs and the

frequency of events. The chance of a predicted exceedance is determined from air

dispersion model predictions as the number of predicted exceedances divided by

the duration of the meteorological data file used. The frequency of events is how

often a source emits over a year

Directive 060 outlines the low risk criteria (2011) that was developed for well test

flaring and can be applied to modelling results for all non-routine sour gas flaring

events. The ERCB low risk criteria considers exceedances based on each hour of

the modelling period rather than on a receptor basis like the ESRD modelling

criteria. Therefore, it is not possible to do a comparative analysis of the two

methods.

This document outlines the new regulatory approach and comprehensive plan for

managing non-routine flaring as developed by the NRFTT, and the process that

lead to its development.

This document is also a historical account of the work done by the NRFTT. As

such, the document uses the previous name of the newly created Alberta Energy

Regulator, that being the Energy Resources Conservation Board. This was simply

done for continuity purposes within the historical record.

November 15, 2013 Non-Routine Flaring Framework Page iv

Non-routine Flaring Task Team List of Acronyms

AAAQOs Alberta Ambient Air Quality Objectives

AENV Alberta Environment

AER Alberta Energy Regulator

AQMG Air Quality Model Guideline

AQMP Air Quality Management Plan

AUPRF Alberta Upstream Petroleum Research Fund

BMP Best Management Practices

CAPP Canadian Association of Petroleum Producers

D060 Directive 060

D071 Directive 071

EPEA Environmental Protection and Enhancement Act

ERCB Energy Resources Conservation Board

ESRD Alberta Environment and Sustainable Resource Development

EUB Energy and Utilities Board

FMSF Flare Management Strategy Flowchart

GUI Graphical User Interface

H2S Hydrogen Sulphide

NRFTT Non-routine Flaring Task Team

PSV(s) Pressure Safety Valve(s)

PTAC Petroleum Technology Alliance Canada

RBC Risk Based Criteria

SEPAC Small Explorers and Producers Association of Canada

SO2 Sulphur Dioxide

TOR Terms of Reference

November 15, 2013 Non-Routine Flaring Framework Page v

US EPA United States Environmental Protection Agency

November 15, 2013 Non-Routine Flaring Framework Page vi

Contents

Overview ............................................................................................................................. ii

1 Introduction ..............................................................................................................1

2 Background ..............................................................................................................3

2.1 Previous Regulatory Approach ....................................................................3 2.2 Formation of Non-routine Flaring Task Team .............................................4 2.3 Potential Solutions .......................................................................................5 2.4 Comprehensive Non-Routine Flaring Framework.......................................5

3 Best Management Practices for Facility Flare Reduction ........................................7

4 Air Dispersion Modelling Guidance ......................................................................12

4.1 Sources to be Modelled ..............................................................................14

5 Meteorological Data Improvements ......................................................................15

6 Risk-Based Modelling Criteria for Non-routine Flaring .......................................16

6.1 Calculation of Risk ....................................................................................16 6.2 AQMG Routine Emission Source Modelling Criteria ...............................17

6.3 ERCB Low Risk Criteria ...........................................................................17 6.4 Risk-Based Modelling Criteria for Non-Routine Flares ............................18

6.4.1 Planned Flaring ..............................................................................19

6.4.2 Unplanned Flaring .........................................................................19

6.5 Discussion ..................................................................................................20

7 Pilot Initial 2007-08 Test of Concept Program ......................................................22

8 Comprehensive Management for Non-Routine Flaring ........................................23

9 Development of Dispersion Modelling Tools ........................................................27

10 Timelines – Implementation ..................................................................................28

11 Next Steps ..........................................................................................................2928

References ..........................................................................................................................30

November 15, 2013 Non-Routine Flaring Framework Page vii

Figures

Figure 3.1 Flare Management Strategy Flowchart ................................................................. 11 Figure 6.1 Graphical Representation of Non-Routine Modelling Hourly Risk Criteria ........ 21 Figure 8.1 Comprehensive Management for Non-Routine Flaring of Sour Gas ................... 26

Tables

Table 2.1 Potential Solutions Identified and Evaluated .......................................................... 5 Table 6.1 Summary of Non-Routine Modelling Hourly Risk Criteria ................................. 21

November 15, 2013 Non-Routine Flaring Framework 1

1 Introduction

Flaring is a controlled combustion process used to dispose of natural gases (sweet

gas, sour gas, acid gas or other hydrocarbon vapour) through a vertical stack.

Facilities in the oil and gas industry may routinely flare small volumes of natural

gas that are technically difficult and/or uneconomic to conserve. Flaring is also an

important safety measure, used to safely dispose of natural gas that would

otherwise pose a hazard to workers, nearby residents and facility equipment

during non-routine occurrences like emergencies, process upsets, equipment

failure and power failure conditions. Flaring is recognized as an important issue

for the upstream oil and gas industry for health, safety and environmental impacts,

as well as conservation of energy resources.

Sour gas flaring is a concern to the environment as it results in the emissions of

sulphur dioxide (SO2) that on both a short-term and long-term basis, and at high

enough concentrations and exposure durations can have adverse impacts on

humans and animals and can cause damage to vegetation. Additionally, on a long-

term basis, SO2 emissions can also contribute to acidification of soils and water

bodies. For these reasons, flaring is a strictly regulated process of the oil and gas

industry.

Flaring can occur during routine and non-routine situations. Routine events occur

as a result of the normal operation of a facility or process while non-routine

events are considered as outside the normal operation of a facility. Non-routine

flaring occurs during events such as planned maintenance activities, and

unplanned upsets and emergencies, and are usually both infrequent and of short

duration.

Energy Resources Conservation Board (ERCB) Directive 060: Upstream

Petroleum Industry Flaring, Incinerating, and Venting (D060) (ERCB2011) is the

regulatory document (as amended from time to time) that outlines requirements,

guidelines and recommendations for flaring, incineration and venting in the

upstream oil and gas industry in Alberta. D060 was first introduced in 1999 with a

subsequent clarification document released in 2001. Part of the flare performance

requirements in D060 is that all existing and proposed permanent stacks that

flare sour gas must be designed to meet the requirements set by Alberta

Environment and Sustainable Resource Development (ESRD), formerly Alberta

Environment, mainly the Alberta Ambient Air Quality Objectives (AAAQOs)

(ESRD 2013) for SO2. Compliance with the SO2 AAAQO is usually evaluated by

completing an air dispersion modelling assessment for the possible flaring events.

Flare stacks used for non-routine situations were required to be evaluated as

continuous sources and there was no consideration given to the frequency or

duration of the flaring event. It should be noted that all flaring from temporary

stacks (e.g. well test flaring) needs an approval from the AER unless exempt as

outlined in D060.

Compliance with the flare performance requirements in D060 were to be

completed for all facilities by the end of 2004. In the process of completing this

work, industry determined that for many existing facilities with permanent flares


used for non-routine purposes, there was no practical or economic solution to

comply with these requirements using existing air dispersion modelling

methodologies. The problem was most pronounced in areas of complex terrain,

predominantly in the foothills areas. A number of possible solutions such as

increasing stack height or adding fuel gas were examined by industry. However,

none were found to adequately address the problem. The Canadian Association of

Petroleum Producers (CAPP) formed the Non-Routine Flaring Task Team

(NRFTT) comprised of government and industry members to look into this

problem. This document outlines the new regulatory approach and comprehensive

plan for managing non-routine flaring as developed by the NRFTT, and the

process that lead to its development.


2 Background

2.1 Previous Regulatory Approach

Prior to development of the Risk Based Criteria the previous regulatory approach

for addressing non-routine flares was found at that time in D060 and stated:

“Devices for combustion of sour or acid gas must be designed and evaluated to

ensure compliance with the Alberta Ambient Air Quality Objectives for SO2 in all

cases including short-duration non-routine cases. Evaluations must be conducted

using methodologies acceptable to the EUB Operations Group and Alberta

Environment. One of the methods described in Section 3.6, Section 7.12, or

Alberta Environment’s Emergency/Process Upset—Flaring Management

Modelling Guidance must be used.”

Air dispersion modelling predictions of SO2 from non-routine sour gas flares were

to meet the ESRD requirements for continuous sources or the ERCB requirements

for well test flaring. Both the ESRD and ERCB requirements had risk-based

criteria, that is, modelling predictions were allowed a chance of exceeding the

AAAQOs. As outlined in ESRD Air Quality Model Guideline (AQMG) (ESRD

2013), the ESRD criteria for non-routine emission sources based on requirements

for a continuous source were:

99.9th percentile predicted hourly SO2 concentration at each receptor must

meet the 1-hr AAAQO for SO2.

As outlined in D060, the ERCB Low Risk Criteria for non-routine flaring based

on requirements for well test flaring or incineration were:

99th percentile predicted hourly SO2 concentration for all hours of the

modelling period must meet the 1-hr AAAQO for SO2, and

maximum predicted hourly SO2 concentration must not exceed 900 µg/m3.

Due to the short duration and infrequent nature of non-routine flaring, impacts for

averaging periods longer than 1-hr are not usually evaluated; however, operators

have to be duly diligent in ensuring compliance with all AAAQOs for SO2.

The ESRD Emergency/Process Upset Flaring Management: Modelling Guidance

(ESRD 2003) identified a need to account for the likelihood of whether flaring

will occur during a period of worst-case meteorology.

If modelling results show compliance with the AAAQOs within the currently

accepted risk levels then the facility is considered to be in compliance.

Conversely, if modelling results for an existing facility indicate exceedances of

the AAAQOs beyond the currently accepted risk levels, the facility is considered

to be out of compliance. As a result, the facility will need to be modified to meet

the regulations or a plan to manage non-routine flaring will be required to ensure

the AAAQOs are not exceeded. For proposed facilities, redesign is required to

meet the regulations if modelling predicts exceedances.


2.2 Formation of Non-routine Flaring Task Team

Compliance with the flare performance requirements including non-routine events

in D060 were required by December 31, 2004. In the process of completing this

work, it was found that for many existing facilities with permanent flares that

were used for non-routine purposes, there was no practical or economic solution

to comply with D060 given the current modelling requirements. However, the

ERCB and ESRD would accept a management plan to deal with flaring during

non-routine situations as was done in well test flaring or other planned flaring

situations but it was found that certain aspects of this type of flare management

was not practical either. The facilities in question range from small facilities along

a pipeline or at a wellsite, to larger compressor stations, to large sour gas

processing plants.

It was industry’s position that given the great expense required to retrofit existing

facilities to ensure compliance, the low risk involved with non-compliance for

such isolated and short flare durations, the resources could be better targeted to

projects yielding far greater gains environmentally. Further, flaring is already

minimized at these sites, as it is an economic disadvantage to flare gas that could

otherwise be sold. If other options are available, such as sending gas down the

line to a plant, then gas is not flared. However, there are some cases when there is

no other option to flaring.

Industry also put forth that the requirements in D060 for non-routine flares to be

modelled as a continuous source regardless of actual flaring frequency or duration

were not representative of whether a particular facility would be in compliance

with the AAAQO for SO2. For example, even if flaring at a facility occurs only

five times a year for an hour at a time, it would need to be designed as if it were

operating every second of the year.

In response to the issue of non-routine flaring, CAPP formed the SO2 Dispersion

Modelling Task Force in early 2004. In September 2004, CAPP approached the

ERCB (formerly the Alberta Energy and Utilities Board) and ESRD and formally

presented their view of the issues. The ERCB and ESRD representatives both

agreed that there was a potential problem in the way non-routine flaring at

facilities with permanent flare stacks were being assessed and that more work

needed to be done to properly understand all the issues.

In December 2004, the ERCB formally acknowledged to CAPP that work needed

to be done regarding the assessment of non-routine flaring from permanent stacks.

The ERCB provided a letter to CAPP informing them that enforcement action will

not be applied on unplanned non-routine flaring at facilities that disclose potential

non compliance due to modelling exceedances or where modelling had not yet

been completed. However all requirements for meeting the AAAQOs are still in

place. The relaxation on enforcement would remain in effect while the task group

was working toward a solution. This letter is shown in Appendix A. At this time,

the task group was known the CAPP Non-Routine Flaring Task Team (NRFTT),

and was compromised of representatives from CAPP, ESRD, and the ERCB.


2.3 Potential Solutions

The main underlying point emphasized within the NRFTT from its inception

was that reduction in flare volumes was paramount. This was shared by both

industry and government members. The development of a dataset containing non-

routine flaring modelling results from a large number and varied types of facilities

was commissioned and the results evaluated. A dataset of approximately 130

facilities was created, most of which failed the current non-routine flaring

modelling requirements as outlined previously, and contained a wide range of

facilities from small field facilities to large gas plants. The objective of this

exercise was to demonstrate the scope of the issue, obtain buy-in from all

members on the task team and to provide a measuring stick in which to evaluate

potential solutions.

A number of potential solutions to the non-routine flaring assessment issue were

identified by the NRFTT. The task team considered a number of factors when

evaluating solutions including reduction in flare volumes, practicality, economics,

and technical issues. The potential solutions can be divided into three categories:

Physical or operational modification of facilities; changes to modelling approach;

and changes to regulatory approach. Table 2.1Table 2.1 presents the alternatives

identified and evaluated by the task team. A detailed discussion of each of the

alternatives is shown in Appendix B.

Table 2.1 Potential Solutions Identified and Evaluated

Physical or operational

modification of facilities

Changes to modelling

approach

Changes to regulatory

approach

Increase stack height

Fuel gas addition

Installing more block valves

on pipelines

Sweetening or filters

Nitrogen purging

Giant fans

Incinerators

Relocating flare stacks

Eliminate or reduce flaring

Modelling adjustments

Alternate models

Consider parallel airflow only

Improved meteorological data

Spill assessments

Ambient monitoring

Risk Based Criteria approach

Applicability of the AAAQO

Approach in British Columbia

Real time modelling

2.4 Comprehensive Non-Routine Flaring Framework

It was understood that at some facilities it was possible to implement one or more

of the physical or operational modifications and achieve compliance with the

current regulations; however, this was not true for every facility and consistency

is required for practical regulation. The NRFTT agreed that a comprehensive

solution is necessary to address emissions and air dispersion modelling for non-

routine flares. A restructured non-routine flaring management framework and

modelling methodology is therefore proposed by the NRFTT that will allow the


regulators to make a decision about the acceptability of the existing or proposed

flare system to handle non-routine flaring emissions. The solution should address

minimization of non-routine flare events through physical or operational

modifications to facilities, as well as updating the modelling and regulatory

approach to reflect the nature of these emission sources, and be applicable for new

and existing facilities.

By addressing flare management, duration, magnitude and intensity of non-

routine flare events, their impacts will be reduced, which will minimize the stress

on the environment. And by addressing the modelling methodology, both the

probability of occurrence and margin of error in modelling SO2 from these types

of flare events will be reviewed and acceptable approaches will be identified. It

was agreed that non-routine flares cannot be modelled as continuous sources and

a risk-based approach should be considered. The current ESRD 99.9th percentile

criteria used for continuous routine sources and the ERCB Low Risk Criteria used

for well test flaring could be used as the basis for risk-based modelling for non-

routine flares. The following four main tasks were identified for the task team to

accomplish in developing a comprehensive framework to manage non-routine

flaring:

1) Develop a Best Management Practices for facility flare reduction.

2) Provide improved meteorological data in the province.

3) Provide a guidance document to ensure consistency on modelling non-routine

flares.

4) Develop Risk Based Criteria approach to evaluate modelling results that

considers the frequency of flaring.

From these points a terms of reference (TOR) were developed that outlined the

goals of the NRFTT and identified the tasks needed to be completed to satisfy

those goals. The full TOR is provided in Appendix C.


3 Best Management Practices for Facility Flare Reduction

The main emphasis from the NRFTT was that a reduction in flaring volumes was

a necessary part of the comprehensive management plan for dealing with non-

routine flaring. Each operator had their own protocol or guide on flare reduction;

however, there wasn’t a standard document that could be applied to every

operator and facility that regulators could use as a benchmark to evaluate a

company’s effort to reduce flaring.

The NRFTT commissioned the development of a Best Management Practice for

Facility Flare Reduction (BMP) (CAPP 2006). The NRFTT agreed that the BMP

needs to clearly state that refined modelling using risk-based criteria to interpret

the predicted SO2 ground level concentrations must not pre-empt the flare

reduction/elimination assessments from being done and implemented. The goal of

this team is to reduce the amount of flaring, not to justify non-routine flaring

through refined modelling. The BMP was developed for upstream oil and gas and

is not directly transferable to other industries but it may have applicability to

downstream sectors.

The BMP would provide facility design and operating staff with a recommended

approach to identify routine and non-routine flare sources and quantities, and

assesses the opportunity for reduction of flare volumes and frequency at their

operated facility. In addition, the document could be used as a performance

indicator by regulators to ensure that an effort was being made to reduce flaring

volumes. The thought was not to make this document a regulatory requirement

but to use it as a regulatory standard that could be used in conjunction with the

other non-routine flaring management plan sections for compliance and

enforcement. Although it arose from issues around non-routine flaring of sour

gas, the BMP would be applicable for reducing flaring at all upstream facilities

during any type of event: routine or non-routine, sweet or sour, and can also apply

to venting and incineration. The BMP is a CAPP publication that is available on

the CAPP website1.

The primary objective of the BMP is to provide a process for enabling facilities to

reduce flare volumes and events with an overall Flare Management Strategy.

Although it is recognized that flare stacks are an essential part of safe facility

design and operation, all operators are expected to work towards the elimination

of routine flaring and reduction of non-routine flare events when economically

and technically feasible. A process is also required for the operators to

demonstrate to the regulators that the BMP was followed.

The long-term industry objective is to eliminate routine flaring and minimize non-

routine flaring. Although BMP modifications in procedures and design can reduce

the frequency of non-routine flaring, emergency flaring is still the most fail-safe

operational measure available to prevent equipment overpressure, catastrophic

equipment failure and loss of human life.

1 http://www.capp.ca/getdoc.aspx?DocId=114231&DT=NTV

http://www.capp.ca/getdoc.aspx?DocId=114231&DT=NTV


However, flaring simply because it is convenient to do so or because it has

been a long-standing industry operating practice is unacceptable.

By identifying flare sources and gaps between facility design and BMP design

principles, design staff will be able to identify equipment and process

modifications necessary for reducing flare volumes and frequency for both

existing and new facilities. Similarly, operations staff will be able to identify new

operating practices needed for flare reduction by reviewing current flare sources

and identifying gaps between current operating practices and BMP operating

practices

This BMP is based on current available technology, current regulatory

requirements and accepted industry practices. As technology advances, the BMP

will be updated and there will be more opportunities for routine and non-routine

flare reduction. Although the BMP process outlined in this document may be used

to achieve compliance with regulated design, operating and air quality

requirements, its main focus is on continuous improvement. As technologies

improve and market conditions change, operators should re-evaluate the

feasibility of reducing flaring beyond regulatory requirements on a continuous

basis. The main sections of the BMP are briefly described below.

Flare Management Strategy provides a discussion of the regulatory elements

of developing a facility flare management strategy and introduces the concept

of continuous improvement in flare reduction. Flare reduction and continuous

improvement are discussed in detail in subsequent sections.

Determine Flare Properties provides guidance on locating actual and potential

flare source events, classification of the flare source as routine or non-routine,

quantification of flare volume and duration, and determining flare causes.

Flare Reduction Assessment provides guidance on identifying and assessing

options to reduce flaring, and includes identifying gaps between current

design/operation versus BMPs, economic assessments of reduction projects,

and the prioritization, implementation and documentation of reduction

projects.

BMP Design Considerations provides guidance on design considerations to

prevent, reduce or partially eliminate routine and non-routine flare volumes

and frequency.

BMP Operating Considerations provides guidance on operating considerations

to prevent, reduce or partially eliminate routine and non-routine flare volumes

and frequency.

Flare Quantification Requirements provides guidance on quantifying all

sources of flares.

Industry members expressed concern with requiring implementation of the BMP

through regulation. The BMP is an industry-developed voluntary guidance

document focused on continuous improvement; if linked to regulation, it will

become a standard operating practice over which industry will no longer have


control or ownership. Conversely, the regulators expressed concern that there

needed to be a process the regulators can use during audits to determine that

facilities are being duly diligent in minimizing flaring. It was agreed that linking

the BMP into regulation was not required however, a regulatory decision tree, as

shown in Figure 3.1, the Flare Management Strategy Flowchart (FMSF) was

developed that is reflective of the practices described in the BMP and will give

the regulators a field tool for compliance and enforcement. Triggering the flare

reduction analysis in the BMP will be based on exceeding the AAAQOs from a

modelling perspective; however, D060 still requires that all facilities go through a

decision tree analysis to eliminate or reduce flaring whenever possible.

One of the main points of the NRFTT was the need for consistent definitions for

topics relating to non-routine flaring. The BMP provided the following definitions

to ensure a consistent understanding of the different terms and topics related to

non-routine flaring:

Routine Flaring - “Routine” applies to continuous or intermittent flaring,

venting and incinerating that occurs on a regular basis due to normal

operation. Examples of routine flaring include: glycol dehydrator reboiler still

vapour flaring; storage tank vapour flaring; flash tank vapour flaring; and

solution gas flaring.

Non-routine Flaring- “Non-routine” applies to intermittent and infrequent

flaring.

Planned flaring – Flare events where the operator has control over when

flaring will occur, how long it will occur, and the flow rates. Planned flaring

results from the intentional de-pressurization of processing equipment or

piping systems. Examples of planned flaring include: pipeline blowdowns;

equipment depressurization; loss of normal control during start-ups; facility

turnarounds; and well tests.

Unplanned flaring - emergency or upset operational activities closely

associated with facility health and safety. Flare events where the operator has

no control of when flaring will occur. There are two types of unplanned

flaring: upset flaring and emergency flaring.

Upset flaring occurs when one or more process parameters fall outside

the allowable operating or design limits and flaring is required to aide

in bringing the production back under control. Examples of upset

flaring include: off-spec product; hydrates; loss of electrical power;

process upset; and operation error.

Emergency flaring occurs when safety controls within the facility are

enacted to depressurize equipment to avoid possible injury or property

loss resulting from explosion, fire, or catastrophic equipment failure.

Examples of emergency flaring include: pressure safety valve (PSV)

overpressure; and emergency shutdown.

Although a comprehensive flare management plan was deemed necessary to

address the compliance and enforcement of non-routine flaring, it was necessary


to find ways of simplifying this plan as much as possible in order to regulate it

practically. As such, to avoid confusion over what flare events are considered

upsets or emergencies, both of these flare events were grouped into unplanned

flare events.


Figure 3.1 Flare Management Strategy Flowchart


4 Air Dispersion Modelling Guidance

Regulatory air dispersion modelling is designed to be conservative (i.e. over

predict concentrations). Compliance with the AAAQOs is measured against

ground-level concentrations predicted to occur during worst case dispersion and

emissions conditions. The previous air dispersion modelling requirements for

non-routine sources are consistent with those for continuous sources and do not

account for the infrequent, short-term nature of non-routine flaring events and as

such are even more conservative. Industry had identified difficulties in meeting

these requirements for non-routine flaring using current modelling approaches,

especially in areas of complex terrain. Air dispersion modelling of non-routine

flaring presents many challenges:

In many instances non-routine flaring occurs as a result of depressuring of

equipment or pipelines so the flow rate would be transient in nature. Most

regulatory models assume constant stack parameters for each hour and cannot

explicitly account for the transient nature of a blowdown Non-routine flaring

events can be less than 1-hour in duration; however, models simulate on an

hourly basis and model predictions need to be adjusted appropriately; and

Non-routine events are infrequent and models cannot explicitly consider when

flaring will or won’t occur.

The NRFTT undertook a review of non-routine flaring air dispersion modelling

tools available, and the results from various companies and consultants showed

inconsistencies in approach and a failure to account for the short-term nature of

the event being modelled. By using a consistent air dispersion modelling

methodology with required emission scenarios defined, the modelling of non-

routine flaring will be better understood and regulated. Therefore, a modelling

guidance document was commissioned by the NRFTT for ESRD. Where required

by regulatory requirements, modelling must be carried out to show due diligence

to protect the environment for non-routine flaring applications.

The ESRD Non-Routine Flaring Management – Modelling Guidance (ESRD

2013) outlines a methodology for air dispersion modelling that should be used to

determine appropriate non-routine flaring management practices. The

methodology has been developed to:

Ensure that consistency is maintained in the modelling for each facility;

Ensure all facilities are evaluated on the same predictive basis; and

Refine dispersion modelling to more realistically predict ground level SO2

concentrations from non-routine sour gas flaring.

There are differing scientific views on the many methods of modelling, and all

facilities are designed differently. However, it is essential that the overall

methodology for assessment is consistent to allow for simple comparison between

different facilities. A refined modelling methodology is therefore proposed. The

objective of refining the sour gas flaring modelling approach is not to change the

target and therefore make it "easier" for industry to demonstrate compliance. The


guidance document can be found on the ESRD website and is summarized in the

following paragraphs:

A tiered modelling approach is proposed:

1) Screening: The purpose of the screening modelling is to determine maximum

predictions in parallel airflow (simple terrain) and complex terrain. Screening

modelling is performed using a spreadsheet tool that defines the source

parameters for dispersion modelling and runs ERCBflare-v1.0 (or its

subsequent versions). If there are no predicted exceedances of the AAAQOs,

the modelling is complete; otherwise Risk Based Criteria modelling (refined

or advanced modelling) is required.

2) Refined: AERMOD or CALPUFF with continuous source modelling option

switches shown in the Modelling Guidance document. Modelling uses five

years of refined meteorological data as required by the AQMG.

3) Advanced: CALPUFF with steady puff or multiple puffs for transient releases

switches shown in the Modelling Guidance document. Modelling uses five

years of refined meteorological data as required by the AQMG.

Refined air dispersion models described in AQMG do not have the capability to

model flares directly; therefore, pseudo stack parameters (e.g. height, diameter)

should be calculated for the flare, to compensate for the flame height, and initial

dispersion from the flame. The following parameters are required as input into the

dispersion models and must be calculated using ERCBflare-v1.0 (or its

subsequent versions):

Effective Stack Height (m);

SO2 Emission Rate (g/s);

Pseudo-Stack Exit Temperature (K);

Pseudo-Stack Exit Velocity (m/s); and

Pseudo-Stack Diameter (m).

The scenarios to be considered for modelling will be identified through the

application of the BMP. All modelling will be conducted using parameters

determined from licensed or approved rates from ERCB and/or Environmental

Protection and Enhancement Act (EPEA) approvals. Maximum expected rates

may be used if the facility is not operating at the rates specified in the license.

Operators need to ensure that worst case scenarios are identified.

As discussed above, there are some challenges associated with non-routine flaring

due to the nature of the events. The following simplifications were determined to

be appropriate:

When determining the flow rate from a transient release, an average flow rate

can be used equal to the volume of the release divided by the duration of the

event. If deemed appropriate, a more rigorous approach using the advanced


model can be undertaken using the time steps of less than 1-hour that

characterize the transient blowdown.

If the flaring model period is more than 1-hour, the flare will be modelled as a

continuous source and the model predictions are directly compared with

AAAQOs. However, if the flare duration is less than 1-hour the predicted

ground level concentrations must be first converted to 1-hour equivalent and

then compared with AAAQOs.

Due to the short duration and infrequency of most non-routine flaring, all

modelling results will be compared to the AAAQOs without considering

baseline concentrations or overlap with other sources.

Another issue identified with modelling was to have the inputs to the models as

accurate or representative as possible. In any modelling assessment, high quality

input data is very important. Maximizing the certainty and validity around the

inputs to the models is the best way to ensure the accuracy of predictions. The

modelling guidance has attempted to provide a consistent and accurate way of

modelling non-routine flaring as well as provide direction on the source inputs to

the model and the meteorology which is discussed in the Section 5.

4.1 Sources to be Modelled

Although it is important to ensure all non-routine scenarios are considered in the

modelling, the focus of this process is on environmental protection and preventing

impacts on human health. This was not intended to be a modelling exercise for

each and every event, so small volume and low SO2 emission non-routine flaring

scenarios (such as releases from PSVs) were considered to be exempt from

modelling as these pose a very low risk. The basis for the exemption is from D060

that requires operators to evaluate impacts of sour gas flaring, incinerating, or

enclosed burning on ambient air quality if it is proposed to burn sour gas

containing more than 10 mol/kmol H2S (1% H2S) or 1 t/d of sulphur (S).

However, for consistency it is proposed that for non-routine flaring the 1 t/d is not

an instantaneous rate but the mass released during the event or the day (for

multiple releases). The modelling exemption for non-routine flaring is

summarized as follows:

1. The licensee, operator, or approval holder must evaluate impacts of non-

routine sour gas flaring on ambient air quality if

a) it is proposed to burn sour gas containing 10 mol/kmol H2S (1 per

cent H2S) or more,

b) 1 tonne of sulphur mass release during the event or the day (for

multiple releases).

Single non-routine flare events that are predicted to be less than or equal to 15

minutes in duration and predicted to emit less than 1 tonne of sulphur over a

rolling 24-hour period are exempt from modelling requirements


5 Meteorological Data Improvements

In any air dispersion modelling assessment, meteorology representative of the

study area is important to ensure the magnitude and distribution of predicted

concentrations are as accurate as possible. This is extremely important in complex

terrain as the frequency of winds blowing towards elevated terrain usually plays a

large role in determining compliance of a facility. It is not practical for every

facility to collect or have collected meteorological data over a number of years

since meteorological data for dispersion modelling requires a great deal more data

than wind speed, wind direction and temperature to adequately characterize the

atmosphere’s ability to disperse a plume. Atmospheric turbulence parameters and

mixing heights are required by air dispersion models and although there are many

ways of determining these parameters, collecting the data required to calculate

these parameters is not trivial or inexpensive.

The lack of representative meteorological data in areas of complex terrain for air

dispersion modelling was identified as a deficiency since the challenges of

assessing non-routine flares were most prevalent in these areas. However, locating

surface or upper air meteorological data that has been collected in complex terrain

area like the foothills, ensuring that these data meet regulatory monitoring

standards and methods, and are consistent was not considered practical. Further,

setting a meteorological monitoring network in the province specifically for this

endeavor was not considered feasible. An alternative methodology to using

measurements from surface stations is the use of modelled mesoscale data to

create dispersion model meteorological data.

ESRD provides a standard data set of five years of meteorological data for use in

refined and advanced modelling. Information on how to obtain this data set can be

found at ESRD’s modelling website.


6 Risk-Based Modelling Criteria for Non-routine Flaring

Risk is defined as the function of the probability of an event and the severity of

the consequence. For the purposes of the NRFTT, risk is a measure of the

probability of an exceedance of the AAAQOs at a receptor on an annual basis. A

risk-based dispersion modelling criteria would account for the likelihood of non-

routine flaring and how often predicted concentrations exceed the AAAQOs. Both

the current ESRD modelling criteria for continuous sources and the ERCB

modelling criteria for well tests are risk-based, that is, there is an allowance for

predictions to exceed the AAAQOs and therefore there is an accepted risk of the

AAAQOs being exceeded. The essential modelling requirement for non-routine

flaring is that an equivalent (or lower) level of risk be maintained as compared to

a continuous source. The risk level from a continuous source as determined from

the modelling criteria is considered to be “acceptable” by the regulators.

Predicted risks from dispersion modelling that meet or are lower than the

“acceptable” risk level would be considered compliant and predicted risks that

exceed this “acceptable” risk level are considered unacceptable and not

compliant.

Prior to adopting the non-routine flaring management framework, air dispersion

modelling for non-routine flaring is performed assuming a continuous source

operating at all hours in the modelling period, which is usually a five year period

as outlined in Section 4. This was considered the correct modelling approach as

non-routine flaring includes unplanned events in which non-routine flaring could

take place at any time and regulators need to know the potential impacts that non-

routine flaring can cause under all possible meteorological conditions. The

problem with this approach is that up to now there has not been a way to address

the infrequent nature of these events. Prior to adopting the non-routine flaring

management framework, the way for determining compliance of non-routine

flares from an air dispersion modelling perspective is the same as a continuous

source or well test as outlined in Section 2.1. Essentially, it has been assumed that

non-routine flares operate continuously for compliance purposes. The section

proposes a Risk Based Criteria air dispersion modelling criteria for non-routine

flaring that considers how often flaring occurs.

For the purposes of the non-routine flaring of sour gas, a Risk Based Criteria is

applicable to SO2 modelling results only. Ambient monitoring must meet the

AAAQOs at all times.

6.1 Calculation of Risk

Risk considers both the chance of a predicted exceedance of the AAAQOs and the

frequency of emissions. The chance of a predicted exceedance is determined from

air dispersion model predictions as the number of predicted exceedances divided

by the duration of the meteorological data file used. The frequency of emissions is

how often a source emits over a year.

Risk = (Frequency of Emissions) × (Chance of an Exceedance of the AAAQOs)


For example, if a continuous emission source (i.e. operating 100% of the time) is

predicted to exceed the 1-hr SO2 AAAQOs 876 hours in one year (8760 hours) at

a receptor, then the annual risk of exceeding the 1-hr SO2 AAAQO at that

receptor associated with this source would be as follows:

Risk = 100% × 876/8760 = 0.1

A reduction in the chance of an exceedance or the frequency of emissions would

reduce the risk.

6.2 AQMG Routine Emission Source Modelling Criteria

The modelling criteria for routine emission sources, in the AQMG, was taken

into account by the NRFTT in developing criteria for non-routine sources

and is presented here for comparative purposes. However, changes to the

modelling criteria for routine emission sources were not considered by the

NRFTT.

Routine emissions include continuous or frequent emissions that occur on a

regular basis due to normal operation of a plant process. Event durations range

from several hours to one year (8760 hours) with emissions occurring more than

one month per year (720 hours per year). The ESRD modelling criteria for routine

continuous SO2 sources and the equivalent risk levels are:

99.9th percentile (9th highest) predicted hourly SO2 concentration at each

receptor for each year must meet the 1-hr SO2 AAAQO. This equates to an

annual risk of exceeding the 1-hr AAAQO of 1×103, (i.e. 8 predicted

exceedances are allowed per 8760 hours and the source is emitting 100% of

the time) at each receptor.

For all other averaging periods the eight highest predicted concentrations (that

were disregarded for the 1-hour averaging period), must be included when

calculating the 99.9th percentile value.

6.3 ERCB Low Risk Criteria

ERCB D060 (2011) outlines the low risk criteria that was developed for well test

flaring and can be applied to modelling results for all non-routine sour gas flaring

events. The ERCB low risk criteria considers exceedances based on each hour of

the modelling period rather than on a receptor basis like the ESRD modelling

criteria. Therefore, it is not possible to do a comparative analysis of the two

methods. The ERCB low risk modelling criteria and the equivalent risk levels are:

99th percentile of the maximum predicted hourly SO2 concentrations at each

hour of the modelling period must meet 1-hr SO2 AAAQO. This equates to a

risk of exceeding the 1-hr AAAQO of 1×10-2 (1% of meteorological

conditions cause exceedances of the 1-hr SO2 AAAQO) in each hour at any

receptor.

The maximum predicted hourly SO2 concentration must not exceed

900 µg/m3. This equates to a negligible risk of exceeding 900 µg/m3, in each

hour at any receptor.


As a result of the work of the NRFTT, the time based ERCB low risk criteria will

be replaced by a new receptor based risk criteria. The criteria is outlined in

section 6.4.1 and the most current version of D060.

6.4 Risk-Based Modelling Criteria for Non-Routine Flares

The proposed non-routine flaring modelling criteria has been developed to ensure

that the predicted risk during non-routine flaring does not exceed that of a

continuous source consistent with the ESRD modelling criteria. The proposed

criteria have limits on hourly modelling predictions. Non-routine flaring is

acknowledged to be infrequent and usually short-term. Therefore, daily, monthly

and annual average criterion are not required for these infrequent, non-continuous

emissions as limits have been placed on the amount of flaring that can occur in a

year.

With a modelling criteria based on risk, there is an acknowledgement that there

could be predicted modelled concentrations that exceed the AAAQOs. To prevent

situations or scenarios that could compromise the safety of the public, a cap or

limit was put on predicted concentrations. The hourly SO2 prediction for non-

routine flaring cannot exceed the SO2 evacuation criteria of 5 parts per million

(ppm) for a 15 minute average as per ERCB Directive 071: Emergency

Preparedness and Response Requirements for the Petroleum Industry (D071)

(ERCB 2008). This equates to a 1-hr SO2 concentration of 9923 µg/m3. These are

criteria for predicted concentrations. To be consistent with the AQMG,

compliance will be tested by considering the 9th highest 1-hour prediction for each

single year of modelling.

The implications of future changes to the SO2 evacuation criteria will need to be

considered. During any non-routine flaring event, any actual measured SO2

concentrations exceeding the AAAQOs directly caused by that event will be

considered a contravention under EPEA.

As outlined in Section 3.0, non-routine flaring is divided to two categories:

planned and unplanned. The risk of exceeding the AAAQOs is dependent on not

only the modelling predictions but also how often flaring will occur. For

simplicity of compliance and enforcement, a maximum allowable frequency of

flaring was determined for each category. Planned emissions occur more

frequently than unplanned emissions. The allowable amount of flaring in each

category was determined in consultation with industry members and are

considered as reasonable for compliance and operations. Once the allowable

amount of flaring was determined, the modelling prediction percentile that would

determine compliance was chosen to ensure that the risk of exceeding the

AAAQOs for a non-routine flare does not exceed that of a continuous routine

flare:

At the worst case receptor, the annual risk of an exceedance of the 1-hour

SO2 AAAQO cannot exceed 1×10-3.


6.4.1 Planned Flaring

Planned flaring includes scheduled intermittent maintenance activities including

well tests and are by definition, events that the operator has control over for the

most part and can choose when to flare, the duration, and the flow rate. Event

durations can range from less than an hour to about 1 week and flaring will be

allowed up to 720 hours (approximately 1 month) per year at a flare. The

following modelling criteria are proposed for planned flaring:

The 99.9th percentile (9th highest of 8760 predictions) predicted hourly

concentrations at each receptor cannot exceed a 1-hr SO2 concentration of 900

µg/m3.

The 99th percentile (e.g., 88th highest of 8760 predictions for modelling of a

full year) predicted hourly concentration at each receptor must not exceed the

1-hour SO2 AAAQO. Flaring cannot occur more than 720 hours in a calendar

year. This equates to a maximum risk of exceeding the 1-hr AAAQO of

8.2×10-4 at each receptor (the risk calculation formula is shown in Table 6.1).

An Air Quality Management Plan (AQMP) can be implemented for planned

flaring events. An AQMP identifies times, operational instructions,

meteorological restrictions, and/or ambient monitoring so that the AAAQOs

are not exceeded during flaring.

6.4.2 Unplanned Flaring

Unplanned flaring includes unscheduled intermittent activities including upsets

and emergencies and are by definition, events that the operator does not have

control over and cannot choose when to flare, the duration, or the flow rate. Event

durations range from minutes to four hours and flaring will be allowed up to 88

hours per year at a flare. The following criteria are proposed for unplanned

flaring:

The 9th highest predicted 1-hr SO2 concentration for each single year of

modelling cannot exceed the SO2 evacuation criteria from ERCB D071 which

equates to a 1-hr SO2 concentration of 9923 µg/m3.

The 90th percentile (876th highest of 8760 predictions) predicted hourly SO2

concentration at each receptor must meet the 1-hour SO2 AAAQO. Flaring

cannot occur more than 88 hours in a calendar year. This equates to a risk of

exceeding the 1-hr AAAQO of 1.0×10-3, at each receptor (the risk calculation

formula is shown in Table 6.1).

Due to their unexpected nature of the cause of the flaring, AQMPs with

restrictions based on meteorology or time of day, or ambient monitoring

cannot be implemented for unplanned flaring events. However, unplanned

flaring can be managed to reduce the predicted SO2 concentrations to meet the

risk-based criteria.


6.5 Discussion

Figures 6.1 illustrates the relationship between the current Risk Based Criteria for

a continuous source and the criteria proposed for non-routine flares (planned and

unplanned events), for the hourly objective. On the x-axis is the chance of

predictions exceeding the AAAQOs (hours of predicted exceedances/hours of

emissions modelled). A minimum of one year (8760 hours) of meteorological data

is required as the risks are on an annual basis. On the y-axis is the fraction of the

year the source is emitting (hours of emissions/hours in a year). The green

diagonal line represents the equivalent level of risk as a continuous source, is the

product of the two axes and is the annual risk of exceeding the AAAQOs. It can

be seen on the figures that the annual risk of exceeding the hourly AAAQOs is

1.0×10-3 which is based on a continuous source. The highest risk is in the upper

right hand corner (shaded red) and the lowest risk is in the lower left hand corner

(shaded green). As you move toward the upper right portion of the graph the risks

increase and as you move toward the bottom left portion of the graph the risks

decrease. Areas on the graph with risks less than the ESRD modelling criteria for

continuous sources are shaded green and are considered as areas of acceptable

risk. Areas on the graph with risks greater than the ESRD modelling criteria for

continuous sources are shaded red and are considered as areas of unacceptable

risk.

The premise behind the proposed criteria for non-routine flares is to ensure that

the risk of exceeding the AAAQOs is equal to or lower than the risks acceptable

for a continuous source. The non-routine flaring categories are limited within each

category to a maximum allowable number of hours of flaring per year (y-axis)

and to a chance that a predicted concentration exceeds the AAAQOs assuming the

source was operating continuously (x-axis). The maximum percentiles of

predicted concentrations allowable are shown on the graphs in red font. Table 6.1

shows the calculations for determining the risk of exceeding the hourly AAAQOs.

For planned non-routine flaring events, the flare would be considered to have an

annual risk of exceeding the AAAQOs that is equal to or lower than that of a

continuous source if:

the 99th percentile hourly SO2 concentration is less than the hourly

AAAQO;

the 99.9th percentile hourly SO2 concentration is less than 900 ug/m3; and

the flaring does not occur for more than 720 hours per year.

Under the above circumstances, from a modelling perspective, the flare would be

in compliance.

For unplanned non-routine flaring events, the flare would be considered to have

an annual risk of exceeding the AAAQOs that is equal to or lower than that of a

continuous source if:

the 90th percentile hourly SO2 concentration is less than the hourly

AAAQO;


the 99.9th percentile hourly SO2 concentration is less than 9923 ug/m3; and

the flaring does not occur for more than 88 hours per year.

Under the above circumstances, from a modelling perspective, the flare would be

in compliance.

Table 6.1 Summary of Non-Routine Modelling Hourly Risk Criteria

Flaring

Category

Fraction

of Year

Source is

Emitting

Hours

per Year

Source

Emitting

Chance of

Hourly

Prediction

Exceeding

Air Quality

Threshold

Percentile

Hourly

Prediction

Meeting

Air

Quality

Threshold

Annual

Risk of

Exceeding

Air Quality

Threshold

Maximum

Acceptable

1-hr Air

Quality

Threshold

Years per

Predicted

Exceedance

Continuous

Routine 100% 8760 0.10% 99.9% 1.0E-03 450 µg/m3 1,000

Planned

Non-routine 8.2% 720

1%

0.10%

99.0%

99.9%

8.2E-04

8.2E-05

450 µg/m3

900 µg/m3

1,217

12,167

Unplanned

Non-routine 1.0% 88

10%

0.10%

90.0%

99.9%

1.0E-03

1.0E-05

450 µg/m3

9,923 µg/m3

1,000

100,000

Formula Input A

Y axis A×8760

input B

X axis P=1-B R=A×B

AAAQO &

RBC =1/R

Figure 6.1 Graphical Representation of Non-Routine Modelling Hourly Risk Based Criteria


7 Pilot Initial 2007-08 Test of Concept Program

Discussions on the Risk Based Criteria modelling criteria was an ongoing

endeavour and before coming to a consensus on the proposed criteria, a pilot

study was undertaken to help understand the consequences of the new approach

such as feasibility, practicability, frequency of events, capacity of enforcement

from a regulator’s perspective, and administrative issues.

A number of existing facilities in complex terrain where non-routine flaring of gas

with an H2S content > 10 mol/kmole (1%) has occurred were identified. The BMP

was applied to identify all possible non-routine flaring events and the potential to

reduce flaring. Air dispersion modelling was undertaken using the proposed

modelling refinements with probable worst-case scenarios for both planned and

unplanned events categorized by the application of BMP. The proposed Risk

Based Criteria was applied to the modelling results. As well, data was gathered on

the number of flaring events and volumes during the pilot program at the pilot

sites.

The results of pilot study showed that the proposed changes to the regulatory

approach for dealing with non-routine flaring were reasonable and that the

NRFTT could move forward and develop a recommended approach for the

regulating of non-routine flaring.


8 Comprehensive Management for Non-Routine Flaring

Operators must ensure compliance with all provincial regulatory requirements in

regards to flaring and ambient air quality. Requirements for flaring and venting

activities in Alberta can be found in D060. D060 requirements also work to

ensure compliance with the AAAQOs.

The main regulatory issue with non-routine flaring is that the AAAQOs are to be

met during any actual non-routine flaring event on a monitoring basis, where it is

occurring. Monitored exceedances of the AAAQOs must be reported and may be

subject to enforcement action by ESRD or ERCB. Figure 8.1 illustrates the

proposed regulatory approach to non-routine flaring and is described below:

1. Performing Screening Level Assessment of Non-Routine Flaring using

ERCBflare-v1.0 spreadsheet (or its subsequent versions):

If these results show compliance with AAAQO then follow requirements

in D060 for flare reduction. Otherwise, follow the Comprehensive

Management for Non-Routine Flaring, below (Steps 2 through 7, as

applicable); and

If screening modelling for 99.9th percentile meets AAAQO’s, operate

according to D060.

2. Apply FMSF (Figure 3.1) (Applicable for all sweet and sour facilities);

Applies only to the facilities that do not meet the AAAQOs from a

modelling perspective;

Needs to be done before refined non-routine Risk Based Criteria

modelling is performed;

Companies should have on file a description of how the FMSF was

applied (Figure 3.1) which must be provided to ESRD and ERCB upon

request; and

Re-apply FMSF upon significant operational or design changes.

3. Perform air dispersion modelling for non-routine flaring;

Applicable to all facilities with permanent flares with H2S > = 1% OR > =

1 t/d of sulphur EXCEPT if < = 15 minutes AND < = 1 t/d of sulphur

over a roiling 24-hour period (see section 4.1);

Follow Modelling Guidance (ESRD 2013); and

Provide justification that worst-case scenario identified is worst case with

regard to magnitude and frequency of predicted concentrations.

4. For new facilities, modelling of non-routine flaring must meet the Risk Based

Criteria.

5. For existing facilities, the following procedure is proposed:

a. If modelling of worst case scenario(s) at licensed or approved conditions

shows compliance with AAAQOs:


Facility can continue to operate as is;

Re-apply FMSF as directed by the regulator or if any changes at the

facility would result in changes to flaring scenarios; and

Re-assess modelling if any changes at facility.

b. If modelling of worst case scenario(s) at licensed or approved conditions

shows compliance with Risk Based Criteria:

Company must log the number of hours of flaring in each category

(planned and unplanned) per calendar year. Information to be provided

to ESRD and/or ERCB upon request.

c. If the allowable number of hours of flaring in any category is exceeded in

a calendar year, the operator must disclose this to ESRD and/or ERCB.

Any exceedances of AAAQOs predicted from the post event modelling

would be considered as an actual monitored exceedance of the AAAQOs

unless ambient air monitoring (if available) did not record exceedances at

the location of the predicted exceedances:

If non-compliance with Risk Based Criteria is due to modelling at

licensed or approved values at which the facility historically does not

operate, then the facility may consider modelling at maximum

expected conditions and remodelling if these conditions change.

Company must log the number of hours of flaring in each category

(planned and unplanned) per calendar year. This information to be

provided to ESRD and/or ERCB upon request.

For planned events (maintenance, etc), it is expected that operators

will develop AQMPs to ensure that exceedances do not occur, and

implement them during flaring. It is acceptable for modelling to be

based on actual flows and gas composition and not on licensed values.

It is acknowledged that in certain situations, modelling may show

compliance with AAAQOs for less than worst-case conditions, and

therefore AQMPs may not be required in all cases. Flare logs and

AQMPs for planned flaring events must be provided to ESRD and/or

ERCB upon request.

For unplanned events:

i. If modelling of worst case scenario(s) show predicted

concentrations in excess of the ERCB SO2 Evacuation Criteria

from D071, then facility has three years to implement design or

operational changes such that Risk Based Criteria is met or else

shutdown the facility. In the interim, for each unplanned flaring

event at the facility, the operator must perform post event

modelling using actual conditions that occurred during the event.

Operators must notify the ERCB immediately upon realizing that

facility design or operational changes cannot be completed within

the three year implementation period.


ii. If modelling of worst case scenario(s) show predicted

concentrations are greater than the AAAQO but less than ERCB

SO2 Evacuation Criteria, then for each unplanned flaring event at

the facility, the operator must perform post event modelling using

actual conditions (source and meteorology) that occurred during

the event.

iii. Any exceedances of AAAQOs predicted from the post event

modelling would be considered as an actual monitored exceedance

of the AAAQOs unless ambient air monitoring (if available)

confirms no actual exceedances at the location of the predicted

exceedances.

6. For situations triggering post-event modelling, the assessment is due two

months from the non-routine flaring event. Up to a two month extension may

be granted upon submission of a letter to the ERCB stating reason for

extension.

7. All existing facilities not meeting the modelling Risk Based Criteria for

unplanned flaring would have to re-assess with the FMSF of each flaring

event and provide documentation to ESRD and ERCB upon request.


Figure 8.1 Comprehensive Management for Non-Routine Flaring of Sour Gas


9 Development of Dispersion Modelling Tools

The ERCBflare-v1.0 dispersion modelling tool was originally intended for

screening purposes, specifically for well test permit applications. The Excel

tool was based on the SCREEN3 dispersion model and it is most suitable for

steady flow rate scenarios. During the development of the Risk Based Criteria,

the United States Environmental Protection Agency (US EPA) changed its

preferred model to AERMOD. This announcement in conjunction with the

need to incorporate the Risk Based Criteria into publicly available tools

prompted the need to develop new dispersion modelling Graphical User

Interfaces (GUI).

Several members of the NRFTT are also members of the Petroleum

Technology Alliance Canada (PTAC) committee called Alberta Upstream

Petroleum Research Fund (AUPRF). AUPRF is an industry-sponsored fund

supported by CAPP and Small Explorers and Producers Association of

Canada (SEPAC). The objective of AUPRF is to provide an efficient and

effective mechanism to coordinate, initiate, fund, complete and communicate

on environmental research needed by the industry and government regulators

enabling a prosperous upstream oil and gas industry achieving socially and

environmentally responsible recovery of Canada’s petroleum resources

through effective, market-driven collaboration. The AUPRF Fund supports

practical science-based studies that develop credible and relevant information

to address knowledge gaps in the understanding and management of high

priority environmental and social matters related to oil and gas exploration

and development in Alberta. Research reports are shared broadly with the oil

and gas industry as well as regulators, government agencies, and other

stakeholders. PTAC works closely with CAPP to align AUPRF priorities and

criteria to CAPP policy objectives. The resulting research has and continues to

be used by governments and regulators to set or revise environmental

guidelines based on solid scientific evidence and by industry to establish best

practices. In 2009, a proposal to develop a new dispersion modelling tool was

approved by CAPP and PTAC.

The CALPUFF Excel based GUI called ABflare was the first dispersion

modelling tool developed. ABflare was selected first due to CALPUFF’s

ability to model sub hourly scenarios. A consultant, Zeltpsi in association with

Exponent (developers of the original CALPUFF dispersion model) developed

ABflare to be made available to the public free of charge. The original intent

of the NRFTT was to continue using existing screening tools (then

ERCBflare-v1.0) and to use ABflare as the refined model of choice. The US

EPA’s announcement to adopt AERMOD as their preferred model caused

ESRD to update the AQMG. ESRD will no longer accept SCREEN3 for

EPEA approval and amendment applications. This change created a need to

develop a new screening tool based on AERMOD. In 2011, a proposal to

develop a new screening dispersion modelling tool (ERCBflare-v2.0 or its

subsequent versions) was approved by CAPP and PTAC.


A main focus of the dispersion modelling tools was to standardize how source

input parameters are calculated. The new tool includes transient blowdown

source modelling and updated algorithms to predict flare conversion

efficiency. Flare conversion efficiency is based on the University of Alberta

Flare Research Project © 2000, 2004 by Larry Kostiuk, Matthew Johnson, and

Glen Thomas. The new models were designed to predict conversion

efficiencies which prompted the developer to consider H2S as part of the air

quality assessment. In cases, where plume momentum is low and in high wind

conditions, combustion conversion efficiencies are low enough such that the

AAAQO for H2S is of concern and cannot be ignored. The decision to include

predicted ground level H2S concentrations in ABFlare and AERFlare-v2.0 (or

their subsequent versions) was initiated by the regulators where there was

limited time to analyze all of the implications of adding this layer of

modelling. The need for ongoing evaluation of modelling methodologies and

the risk-based criteria has been acknowledged by both industry and the

regulators. Therefore, the Non Routine Flaring Task Team will continue to

work under a new Terms of Reference in order to address and resolve any

identified issues or concerns surrounding the risk-based criteria, supporting

guidance and modelling approach.

10 Timelines – Implementation

A phased in approach for this regulation based on facility type is the most

effective method because facility type offers a reasonable surrogate for

prioritization based on level of risk of exceeding AAAQOs due to flow rate and

flow volumes. The relative ease in identifying facilities based on type provides

administrative simplicity for regulatory inspectors and companies, and offers a

consistent and standardized identification throughout the province. Hence, the

following timelines to assess non-routine flaring are proposed:

1) Where previous modelling of non-routine flare events shows compliance

with the AAAQO using tools and methods no longer accepted by ESRD (e.g.

SCREEN3, RTDM, ISC3, AQMG and ERCB low risk criteria), the facility can

continue to operate as is. If any emission changes occur at the respective facility

or if the AER requests new dispersion modelling be conducted for any reason, the

operator will apply the flare management strategy flowchart and will re-assess

dispersion modelling using current modelling methodology and tools.

2) For permanent flare stacks the licensee, operator, or approval holder must

assess non routine flaring dispersion modelling criteria within the following

timelines where facilities lack dispersion modelling or where facilities are unable

to satisfy the AAAQO for non-routine flaring events using tools and methods no

longer accepted by ESRD:

a) Sour Gas Processing Plants: Within one year upon sanctioning of the

Framework.


b) Compressor stations and oil and gas batteries: Within two years following

sanctioning of the Framework.

c) Well sites and pipeline risers: Within four years following sanctioning of the

Framework.

d) If emissions change at existing AER licensed facilities the licensee, operator

or approval holder must reassess non routine flaring dispersion modelling criteria

when a renewal or amendment is required.

All processing facilities subject to Environmental Protection Enhancement Act –

Activities Designation Regulation must re-model upon renewal.

11 Next Steps

CAPP has indicated to the ERCB that the proposed non-routine flaring

management modelling guidance documentation, modelling tools and regulations

should be reviewed on an ongoing basis. This approach would provide the

NRFTT the opportunity to address and discuss possible resolution to identified

issues or concerns while evaluating the effectiveness of the new regulations to

address air quality related concerns.

The modelling requirements and Risk Based Criteria developed for non-routine

flaring are potentially transferable to almost any short duration and infrequent

emission event in any industry. However, the comprehensive plan to manage

these events developed by the NRFTT is specific to the upstream oil and gas

industry at this time and would not be applicable in other industries. The

downstream oil and gas industry has not been involved with this endeavour and

there is a need to discuss any potential changes to make this process applicable to

that industry or other industries.


References

Alberta Environment and Sustainable Resource Development. 2003.

Emergency/Process Upset Flaring Management: Modelling Guidance.

Alberta Environment and Sustainable Resource Development. 2013. Alberta

Ambient Air Quality Objectives and Guidelines.

Alberta Environment and Sustainable Resource Development. 2013. Air Quality

Model Guideline.

Alberta Environment and Sustainable Resource Development. 2013. Using

Ambient Air Quality Objectives in Industrial Plume Dispersion Modelling

and Individual Industrial Site Monitoring.

Alberta Environment and Sustainable Resource Development. 2013. Non-Routine

Flaring Management; Modelling Guidance.

Canadian Association of Petroleum Producers. 2006. Best Management Practice

for Facility Flare Reduction.

Energy Resources Conservation Board. 2011. Directive 060: Upstream Petroleum

Industry Flaring, Incinerating, and Venting.

Energy Resources Conservation Board. 2008. Directive 071: Emergency

Preparedness and Response Requirements for the Petroleum Industry.

November 15, 2013 Non-Routine Flaring Framework i

Appendix A Letter from the EUB to CAPP on December 23, 2004

November 15, 2013 Non-Routine Flaring Framework ii

December 23, 2004

John Squarek

Canadian Association of Petroleum Producers (CAPP)

Suite 2100, 350 7 Avenue SW

Calgary, AB T2P 3N9

Re: SO2 Dispersion Modelling for Temporary Flaring Events at Permanent Facilities

Dear Mr Squarek:

Section 1.1 of Guide 60 (1999 – currently in effect) requires that flares at existing permanent

facilities meet the flare performance requirements outlined in the Guide by December 31, 2004.

As part of these flare performance requirements, Section 7.3.4 of Guide 60 (1999) requires that

emergency sour and acid gas flares be evaluated for compliance with the Alberta Ambient Air

Quality Objectives (AAQO). If exceedances are predicted, corrective actions must be taken.

These actions include increasing stack heights, adding fuel gas or developing management plans

for such events.

When modelling temporary flaring at these permanent facilities, some of the predicted results

raise the question of whether the modelling protocols, designed primarily for continuous

emission sources, are overly conservative for low-frequency, temporary events. Modelling

predictions show this issue is most prevalent in complex terrain. The Alberta Energy and

Utilities Board (EUB), Alberta Environment, and Canadian Association of Petroleum Producers

(CAPP) have formed a Task Group to review the dispersion modelling for planned and

unplanned temporary flaring events at permanent facilities, such as emergency situations,

pipeline blow downs, maintenance, pressure safety valve releases.

While the Task Group continues to review this subject, operators must disclose (in writing) by

December 31, 2004 or as soon as possible thereafter, all permanent facilities with unresolved

potential of exceedances for unplanned temporary flaring. The EUB will not apply enforcement

consequences where these disclosures have been received.

If dispersion modelling has already been conducted, this information should be used to provide

corrective actions which will minimize predicted exceedances during flaring. Mitigative options

such as operating procedures should be considered. Operators should consult with the EUB if

significant changes in facility design or use of supplemental gas are being considered. Wherever

possible, it is requested that operators provide one disclosure for all of their facilities with

unresolved exceedance predictions rather than submitting multiple disclosures. Disclosures can

be sent to:

Michael Brown, M.Eng. P.Eng.

Operations Group

Alberta Energy and Utilities Board

640 – 5th Avenue S.W.

November 15, 2013 Non-Routine Flaring Framework iii

Calgary, AB T2P 3G4

Disclosures for unplanned temporary flaring at permanent facilities should include:

Location and name of facility;

Summary of potential unplanned temporary flaring scenarios, including flow rates,

duration, and predicted frequency of flaring occurrence;

Predicted downwind SO2 concentrations, if available (provide dispersion modelling

results and management plans, if available);

Topographic map showing 7 kilometre radius surrounding flare stack location, indicating

location of flare stack.

For planned temporary flaring events operators must conduct dispersion modelling where

currently required, prior to flaring. If unresolved predicted exceedances exist, please contact

James Vaughan at (403) 297-7530.

In the event of any unplanned or planned temporary flaring, it should be clearly

understood that all requirements for AAQO compliance are still in place.

Michael Brown, M.Eng. P.Eng.

Senior Production Engineer

Production Section

Operations Group

Compliance and Operations Branch

MB/LD

pc: Heather Douglas, Small Explorers and Producers Association of Canada (SEPAC)

November 15, 2013 Non-Routine Flaring Framework iv

Appendix B Alternative Solutions

November 15, 2013 Non-Routine Flaring Framework v

B.1 Physical modification of facilities

Solution: Increase stack height

Benefits: Increases the likelihood that the plume will disperse more effectively before

reaching the ground. From a modelling standpoint this is an easy item to assess

and if the extra height required is small, would be a fairly easy solution to

implement

Drawbacks: In complex terrain, concentrations can increase with a higher stack. In many cases,

the extra height of the stack required to achieve compliance was not trivial.

Increasing stack heights would have no effect on flare volumes

Conclusion: Possible solution but from a construction, structural, forestry, aesthetics, and

economic standpoints, is not considered practical solution in all cases

Solution: Fuel gas addition

Benefits: Will provide energy to the plume without adding more SO2 emissions. This will

increase plume rise and therefore enhance dispersion.

Drawbacks: Not all facilities have a fuel gas source or enough fuel gas or there exists a

pressure difference between the sources. The addition of fuel gas would increase

flare volumes and increase greenhouse gas emissions

Conclusion: Possible solution though not practical in all cases.

Solution: Installing more block valves on pipelines

Benefits: Would likely reduce flare volumes

Drawbacks: May not influence predicted concentrations as flow rates may not change

appreciably and durations may still remain longer than one hour. An increased

footprint would occur as more surface more leases would be required. Would only

influence the non-routine flaring of gas from pipelines

Conclusion: Possible solution though not practical in all cases

Solution: Sweetening or filters to remove H2S from the gas prior to flaring

Benefits: This would reduce SO2 emissions and therefore predicted SO2 concentrations

Drawbacks: Would not reduce flare volumes. It would not likely work for large flow rates and

would be problematic for unplanned events at small facilities where an amine

system is not located


Solution: Purging system with nitrogen prior to flaring

Benefits: Would eliminate the need to flare

Drawbacks: Could work for planned events but not for unplanned events


November 15, 2013 Non-Routine Flaring Framework vi

Solution: Using giant fans to increase dispersion

Benefits: Theoretically could reduce predicted concentrations

Drawbacks: Would not reduce flare volumes. Need to conduct extensive tests to determine the

effectiveness

Conclusion: Not considered a practical solution in all cases

Solution: Using incinerators instead of flares

Benefits: May improve combustion and conversion efficiency

Drawbacks: Would not necessarily improve dispersion and could increase predicted

concentrations. Would not reduce flare volumes


Solution: Relocating flare stacks from areas of complex terrain

Benefits: Likely reduce impact on environment from SO2 emissions

Drawbacks: Would involve major design and operational considerations. Would likely have no

effect on flare volumes


Solution: Eliminate or reduce flaring

Benefits: Flare reduction is an important regulatory and public interest issue. Reduce impact

on environment from SO2 emissions

Drawbacks: Flaring is an important safety feature built into all oil and gas facilities where

applicable so it is not practical to eliminate flaring. Likely involves design and

operational considerations

Conclusion: Considered to be a reasonable solution in all cases

B.2 Changes to the modelling approach

Solution: Modelling standardization

Benefits: Ensure certainty in dispersion model predictions by providing guidance on how to

model non-routine flaring

Drawbacks: Prescriptive methodology lacks flexibility for unique situations

Conclusion: Considered to be a reasonable solution in all cases

Solution: Using alternate models due to current regulatory models overpredicting in

complex terrain

Benefits: Potentially give more realistic concentration predictions

Drawbacks: Using non-regulatory models would require further guidance and add complexity

to the regulatory process

Conclusion: It was determined that overprediction by the regulatory models is most likely

caused by the inputs to the model such as meteorological data or stack parameters

being less than representative. Using alternate models to those recommended by

AENV is not considered a practical solution

November 15, 2013 Non-Routine Flaring Framework vii

Solution: Improved meteorological data

Benefits: Ensure more certainty in dispersion modelling predictions

Drawbacks: Could be cost prohibitive. Collecting meteorological data now is not an option –

need historic data is get a suitable period to be used for modelling

Conclusion: Considered to be a reasonable solution if data sources are available

Solution: Assume parallel airflow in models

Benefits: May give more representative dispersion modelling predictions in complex terrain

where increased turbulence is not considered

Drawbacks: Difficult to verify results. Ignoring the negative effect of terrain on predicted

concentrations

Conclusion: It is documented that high predictions can occur on elevated terrain so ignoring

terrain is not conservative and goes against standard regulatory approaches. It is

not considered to be a reasonable solution

B.3 Changes to the regulatory approach

Solution: Use an approach similar to what AENV uses for on-land spills which is to assess

the risks to the environment after a spill occurs. This approach would incorporate

corporate or site specific strategy for emergency response

Benefits: Well known regulatory approach

Drawbacks: Potentially too many instances of non-routine flaring to regulate effectively.

Reactive response is not considered practical

Conclusion: It is not considered to be a reasonable solution

Solution: Ambient monitoring

Benefits: Potentially able to precisely determine the impacts of flaring

Drawbacks: Only practical for planned events. Due to infrequency of non-routine flaring, it is

not likely to have monitors in correct location to determine impacts. Not possible

or cost effective to have enough monitors to determine impacts with absolute

certainty


Solution: Consider the infrequency of non-routine flaring using a risk-based modelling

criteria

Benefits: Provide a realistic picture of the impacts of non-routine flaring

Drawbacks: Potential difficulties in regulation of the acceptable risk levels

Conclusion: It is considered to be a reasonable solution

Solution: AAAQO not applicable to non-routine flaring

Benefits: May be applicable to real emergencies

Drawbacks: Health and safety of the public and the environment may be compromised

Conclusion: The regulatory approach is that the AAAQO are applicable at all times from a

monitoring standpoint. The reasons for an exceedance would be considered in any

legal action. It is not considered to be a reasonable solution

November 15, 2013 Non-Routine Flaring Framework viii

Solution: Real-time modelling system

Benefits: Determine impacts from flaring during an event and proactively react to prevent

exceedances of the AAAQO

Drawbacks: Only economical at the large facilities with continuous emissions as well as non-

routine flaring


Solution: Use approach in British Columbia for post flare modelling and foliar injury

considerations

Benefits: Potentially could determine if any environmental damage occurred during a flare

event

Drawbacks: Foliar injury criteria is much higher than AAAQO and requires more resources to

regulate. Reactive rather than proactive approach

Conclusion: Post flare modelling is a reasonable consideration if it is part of an overall strategy

to deal with non-routine flaring. Foliar injury criteria is not considered to be a

reasonable solution

.

November 15, 2013 Non-Routine Flaring Framework ix

Appendix C Terms of Reference for CAPP Non-Routine Flaring Task Team

November 15, 2013 Non-Routine Flaring Framework x

Joint AENV/EUB/CAPP

Non-routine Flaring Task Team

Terms of Reference Background

CAPP has indicated that the current management options may be insufficient to address

predicted ground level SO2 exceedances for non-routine flaring when modelled according to the

current guidelines (EUB Directive 060 and AENV Emergency/Process Upset Flaring

Management Modelling Guidance). In numerous cases the predicted ambient SO2 ground level

concentrations in complex terrain are higher than the Alberta Ambient Air Quality Objectives

and in many situations, the Objectives may not be met by current management practices. It was

decided that a partnership between government and industry will develop a comprehensive

management plan for non-routine flares.

The Non-Routine Flaring Task Team agreed that a comprehensive solution is necessary to

address emissions and air quality modelling for non-routine flares. The solution should address

minimization of non-routine flare events as well as updating air quality modelling to reflect the

nature of these emission sources. Reducing duration, magnitude and intensity of non-routine

flare events will minimize the stress on the environment. Both the probability of occurrence and

margin of error in modelling SO2 from these types of flare events will be reviewed and

acceptable approaches will be identified. It was agreed that the non-routine flares cannot be

modelled as continuous sources and a risk-based approach should be considered. The current

AENV Outlier Criteria used for continuous routine sources and the EUB Low Risk Criteria used

for well test flaring could be used as the basis for risk-based modelling for non-routine flares.

Goals

1. Eliminate/reduce non-routine flaring events through technology review or Best

Management Practices Guidelines.

2. Update air quality modelling guidance documents that are part of regulatory

requirements.

3. Identify under which situations physical modifications to facilities/flare stacks and

operating procedures should be implemented.

Several tasks were identified to meet these goals.

Tasks

1. Develop risk-based modelling criteria for non-routine flaring that address the infrequent,

intermittent nature of non-routine flaring events. (Risk-Based Criteria)

2. Establish a partnership between government and industry to develop representative

meteorological data that can be used for dispersion modelling purposes, including non-

routine flaring assessments in areas that are lacking data such as the foothills. (Met Data)

3. Update air quality modelling guidance documents to reflect the nature of non-routine

flaring and determine if risk-based criteria are met. (Modelling Refinements)

4. Review current technologies and operating practices used in facilities and recommend

changes appropriate to eliminate/reduce the frequency, duration and intensity of flare

November 15, 2013 Non-Routine Flaring Framework xi

events, and develop a Best Management Practices document to assist operators in

reducing non-routine flaring. (BMP)

5. Provide recommendations on the development of an outreach program to help to

implement the findings of the Task Team.

6. Develop a report summarizing the above findings that will include the Task Team’s final

recommendations.

A schedule follows. Task Team members are assigned to one or more of the first four tasks, as

identified below.

Schedule

1. Finalize draft Task Team report by June 30, 2006. Finalize Best Management Practices

document by June 30, 2006.

2. Complete final review of report by AENV, EUB and CAPP by September 30, 2006.

The schedules for the following deliverables are listed for information only, as they do not fall

under the control of the Task Team:

3. Finalize draft changes to EUB Directive 060 and AENV Emergency/Process Upset

Flaring Management Modelling Guidance by August 2006.

4. Initiate public consultations for one month for EUB Directive 060 and AENV

Emergency/Process Upset Flaring Management Modelling Guidance by September 2006.

5. Review public comments and update EUB Directive 060 and AENV Emergency/Process

Upset Flaring Management Modelling Guidance by November 2006.

6. Implement by January 2007.

Sour Non-Routine Flaring

Documents

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