### United States Office of Solid Waste EPA 550­B­99­009 

### Environmental Protection and March 2009 

### Agency Emergency Response www.epa.gov/emergencies



# R I S K M A N A G E M E N T

P R O G R A M

G U I D A N C E

F O R O F F S I T E

C O N S E Q U E N C E

A N A L Y S I S

Office of Emergency ManagementThis document provides guidance to the owner or operator of processes covered by the Chemical Accident Prevention Program rule in the analysis of offsite consequences of accidental releases of su bstances re gulated

under section 112(r) of the Clean Air Act. This document does not su bstitute for EPA's re gulations, nor is it a regulation itself. Thus, it cannot impose legally binding requir ements on EPA, States, or the re gulated community, and may not apply to a particular situation based upon the circumstances. This guidance does not constitute final agency action, and EPA may change it in the future, as appropriate.

### TABLE OF CONTENTS Chapter Page

Table of Potentially Regulated Entities

............................................ viii Roadmap to Offsite Consequence Analysis Guidance by Type of Chemical

.................. x

1 Introduction

................................................................... 1- 1

1.1 Purpose of this Guidance

.................................................. 1-1

1.2 This Guidance Compared to Other Models

.................................... 1-4

1.3 Number of Scenarios to Analyze

............................................ 1-4

1.4 Modeling Issues

......................................................... 1-5

1.5 Steps for Performing the Analysis

........................................... 1-6

1.5.1 Worst-Case Analysis for Toxic Gases

................................. 1-7

1.5.2 Worst-Case Analysis for Toxic Liq uids

................................ 1-7

1.5.3 Worst-Case Analysis for Flammable Su bsta nces

........................ 1-8

1.5.4 Alternative Scenario Analysis for Toxic Gases

.......................... 1-8

1.5.5 Alternative Scenario Analysis for Toxic Liquids

......................... 1-9

1.5.6 Alternative Scenario Analysis for Flammable Substances

.................. 1-9

1.6 Additional Sources of Information

.......................................... 1-10

2 Determining Worst -Case Sc enario

................................................. 2-1

2.1 Definition of Worst -Case Sc enario

.......................................... 2-1

2.2 Determination of Quantity for the Worst -Case Sc enario

.......................... 2-3

2.3 Selecting Worst -Case Sc enarios

............................................. 2-3

3 Release Rates for Toxic Substances

................................................ 3-1

3.1 Release Rates for Toxic Gases

.............................................. 3-1

3.1.1 Unmitigated Releases of Toxic Gas

................................... 3-2

3.1.2 Releases of Toxic Gas in Enclosed Space

.............................. 3-2

3.1.3 Releases of Liquefied Refrigerated Toxic Gas in Diked Area

............... 3-3

3.2 Release Rates for Toxic Liquids

............................................ 3-4

3.2.1 Releases of Toxic Liquids from Pipes

................................. 3-5

3.2.2 Unmitigated Releases of Toxic Liquids

................................ 3-5

3.2.3 Releases of Toxic Liquids with Passive Mitigation

....................... 3-7

3.2.4 Mixtures Containing Toxic Liquids

.................................. 3-11

3.2.5 Release Rate Correction for Toxic Liquids Released at Temperatures

Be e o n o -12 tw en 25 C a d 50 C

.......................................... 3

3.3 Release Rates for Common Water Solutions of Toxic Su bstances and for Oleum

..... 3-14

4 Estimation of Worst -Case Distance to Toxic Endpoint

................................. 4-1

April 15, 1999 i

### TABLE OF CONTENTS (Continued) Chapter Page

5 Estimation of Distance to Overpressure Endpoint for Flammable Su bstances

............... 5-1

5.1 Flammable Substances Not in Mixtures

...................................... 5-1

5.2 Flammable Mixtures

..................................................... 5-2

Reference Tables of Distances for Worst-Case Scenarios

............................... 5-4

Table Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint, F Stability, Wind Speed 1.5 Meters per Second:

1 10-Minute Release, Rural Conditions

........................................ 5-4

2 60-Minute Release, Rural Conditions

........................................ 5-5

3 10-Minute Release, Urban Conditions

........................................ 5-6

4 60-Minute Release, Urban Conditions

........................................ 5-7

Dense Gas Distances to Toxic Endpoint, F Stability, Wind Speed 1.5 Meters per Second:

5 10-Minute Release, Rural Conditions

........................................ 5-8

6 60-Minute Release, Rural Conditions

........................................ 5-9

7 10-Minute Release, Urban Conditions

....................................... 5-10

8 60-Minute Release, Urban Conditions

....................................... 5-11

Chemical-Specific Distances to Toxic Endpoint, Rural and Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second:

9 Anhydrous Ammonia Liquefied Under Pressure

............................... 5-12

10 Non-liquefied Ammonia, Ammonia Liquefied by Refrigeration, or Aqueous

Ammonia

............................................................. 5-13

11 Chlorine

.............................................................. 5-14

12 Sulfur Dioxide (Anhydrous)

............................................... 5-15

Vapor Cloud Explosion Distances for Flammable Su bstances:

13 Distance to Overpressure of 1.0 psi for Vapor Cloud Explosions of 500 - 2,000,000 P ounds of Regulated Flammable Su bstances

.................. 5-16

6 Determining Alternative Release Scenarios

........................................... 6-1

7 Estimation of Release Rates for Alternative Scenarios for Toxic Su bstances

................ 7-1

7.1 Release Rates for Toxic Gases

.............................................. 7-1

7.1.1 Unmitigated Releases of Toxic Gases

................................. 7-1

7.1.2 Mitigated Releases of Toxic Gases

................................... 7-4

April 15, 1999 ii

### TABLE OF CONTENTS (Continued) Chapter Page

7.2 Release Rates for Toxic Liquids

............................................ 7-6

7.2.1 Liquid Release Rate and Quantity Released for Unmitigated Releases

........ 7-7

7.2.2 Liquid Release Rate and Quantity Released for Mitigated Releases

......... 7-10

7.2.3 Evaporation Rate from Liquid Pool

.................................. 7-10

7.2.4 Common Water Solutions and Oleum

................................ 7-14

8 Estimation of Distance to the Endpoint for Alternative Scenarios for Toxic Su bstances

....... 8-1

9 Estimation of Release Rates for Alternative Scenarios for Flammable Su bstances

............ 9-1

9.1 Flammable Gases

........................................................ 9-1

9.2 Flammable Liquids

....................................................... 9-2

10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable

Substances

................................................................... 10-1

10.1 Vapor Cloud Fires

...................................................... 10-1

10.2 Pool Fires

............................................................. 10-5

10.3 BLEVEs

.............................................................. 10-6

10.4 Vapor Cloud Explosion

.................................................. 10-6

Reference Tables of Distances for Alternative Scenarios

............................... 10-9

Table Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint, D Stability, Wind Speed 3.0 Meters per Second:

14 10-Minute Release, Rural Conditions

....................................... 10-9

15 60-Minute Release, Rural Conditions

...................................... 10-10

16 10-Minute Release, Urban Conditions

...................................... 10-11

17 60-Minute Release, Urban Conditions

...................................... 10-12

Dense Gas Distances to Toxic Endpoint, D Stability, Wind Speed 3.0 Meters per Second:

18 10-Minute Release, Rural Conditions

...................................... 10-13

19 60-Minute Release, Rural Conditions

...................................... 10-14

20 10-Minute Release, Urban Conditions

...................................... 10-15

21 60-Minute Release, Urban Conditions

...................................... 10-16

April 15, 1999 iii

### TABLE OF CONTENTS (Continued) Chapter Page

Table Chemical-Specific Distances to Toxic Endpoint, D Stability, Wind Speed 3.0 Meters per

Second:

22 Anhydrous Ammonia Liquefied Under Pressure

.............................. 10-17

23 Non-liquefied Ammonia, Ammonia Liquefied by Refrigeration, or Aqueous

Ammonia

............................................................ 10-18

24 Chlorine

............................................................. 10-19

25 Sulfur Dioxide (Anhydrous)

.............................................. 10-20

Neutrally Buoyant Plume Distances to Lower Flammability Limit (LFL) for Release Rate Divided by LFL:

26 Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second

............... 10-21

27 Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

............... 10-21

Dense Gas Distances to Lower Flammability Limit:

28 Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second

............... 10-22

29 Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

............... 10-23

BLEVE Distances for Flammable Su bstances:

30 Distance to Radiant Heat Dose at Potential Second Degree Burn Threshold Assuming Exposure for Duration of Fireball from BLEVE

.............................. 10-24

11 Estimating Offsite R eceptors

..................................................... 11-1

12 Submitting Offsite Consequence Analysis Information for Risk Manag ement Plan

.......... 12-1

12.1 RMP Data Required for Worst-Case Scenarios for Toxic Su bsta nces

.............. 12-1

12.2 RMP Data Required for Alternative Scenarios for Toxic Su bsta nces

.............. 12-2

12.3 RMP Data Required for Worst-Case Scenarios for Flammable Su bsta nces

.......... 12-3

12.4 RMP Data Required for Alternative Scenarios for Flammable Su bsta nces

.......... 12-3

12.5 Submitting RMPs

....................................................... 12-4

12.6 Other Required Documentation

............................................ 12-4

APPENDICES

Appendix A: References for Consequence Analysis Methods

.................................. A-1

Appendix B: Toxic Su bstances

.......................................................... B-1

B.1 Data for Toxic Substances

................................................. B-1

B.2 Mixtures Containing Toxic Liquids

......................................... B-10

April 15, 1999 iv

### TABLE OF CONTENTS (Continued)

APPENDICES Page

Appendix C: Flammable Su bstances

...................................................... C-1

C.1 Equation for Estimation of Distance to 1 psi Overpressure for Vapor Cloud Explosions

............................................................. C-1

C.2 Mixtures of Flammable Substances

.......................................... C-1

C.3 Data for Flammable Substances

............................................. C-2

Appendix D: Technical Background

....................................................... D-1

D.1 Worst-Case Release Rate for Gases

......................................... D-1

D.1.1 Unmitigated Release

.............................................. D-1

D.1.2 Gaseous Release Inside Building

..................................... D-1

D.2 Worst-Case Release Rate for Liq uids

........................................ D-1

D.2.1 Evaporation Rate Equation

.......................................... D-1

D.2.2 Factors for Evaporation Rate Estimates

................................ D-2

D.2.3 Common Water Solutions and Oleum

................................. D-4

D.2.4 Releases Inside Buildings

........................................... D-5

D.3 Toxic Endpoints

......................................................... D-7

D.4 Reference Tables for Distances to Toxic and Flammable Endpoints

................ D-8

D.4.1 Neutrally Buoyant Gases

........................................... D-8

D.4.2 Dense Gases

..................................................... D-9

D.4.3 Chemical-Specific Reference Tables

................................. D-10

D.4.4 Choice of Reference Table for Dispersion Distances

..................... D-10

D.4.5 Additional Modeling for Comparison

................................ D-12

D.5 Worst-Case Consequence Analysis for Flammable Su bsta nces

................... D-12

D.6 Alternative Scenario Analysis for Gases

..................................... D-13

D.7 Alternative Scenario Analysis for Liquids

.................................... D-15

D.7.1 Releases from Holes in Tanks

...................................... D-15

D.7.2 Releases from Pipes

.............................................. D-17

D.8 Vapor Cloud Fires

...................................................... D-18

D.9 Pool Fires

............................................................. D-18

D.10 BLEVEs

.............................................................. D-21

April 15, 1999 v

### TABLE OF CONTENTS (Continued)

APPENDICES Page

D.11 Alternative Scenario Analysis for Vapor Cloud Explosions

...................... D-23

Appendix E: Worksheets for Offsite Consequence Analysis

.................................... E-1

Worksheet 1. Worst-case Analysis for Toxic Gas

..................................... E-1 Worksheet 2. Worst-case Analysis for Toxic Liquid

................................... E-2 Worksheet 3. Worst-case Analysis for Flammable Substance

............................ E-5 Worksheet 4. Alternative Scenario Analysis for Toxic Gas

.............................. E-6 Worksheet 5. Alternative Scenario Analysis for Toxic Liquid

........................... E-9 Worksheet 6. Alternative Scenario Analysis for Flammable Substance

................... E-13

Appendix F: Chemical Accident Prevention Provisions

........................................ F-1

April 15, 1999 vi

### LIST OF EXHIBITS

Exhibit Page

1 Required Parameters for Mode ling

................................................. 1-3

2 Generic Reference Tables of Distances for Worst-case Scenarios

......................... 4-3

3 Chemical-Specific Reference Tables of Distances for Worst-case Scenarios

................ 4-3

4 Generic Reference Tables of Distances for Alternative Scenarios

......................... 8-2

5 Chemical-Specific Reference Tables of Distances for Alternative Scenarios

................. 8-2

6 Reference Tables of Distances for Vapor Cloud Fires as Alternative Scenario for Flammable

Substances

................................................................... 10-2

A-1 Selected References for Information on Consequence Analysis Methods

................... A-2

B-1 Data for Toxic Gases

............................................................ B-2

B-2 Data for Toxic Liquids

........................................................... B-4

B-3 Data for Water Solutions of Toxic Su bstances and for Oleum

............................ B-7

B-4 Temperature Correction Factors for Liquids Evaporating from Pools at Temperatures

o o o o Between 25 C and 50 C (77 F and 122 F)

......................................... B-8

C-1 Heats of Combustion for Flammable Su bstances

...................................... C-3

C-2 Data for Flammable Gases

........................................................ C-6

C-3 Data for Flammable Liquids

...................................................... C-9

April 15, 1999 vii

### TABLE OF POTENTIALLY REGULATED ENTITIES

This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated under 40 CFR part 68. This table lists the types of entities that EPA is now aware could potentially be regulated by this rule (see Appendix B of the “General Guidance for Risk Management Programs” for a more detailed list of potentially affected NAICS codes). Other types of entities not listed in this table could also be affected. To determine whether your facility is covered by the risk management program rules in part 68, you should carefully examine the applicability criteria discussed in Chapter 1 of the General Guidance and in 40 CFR 68.10. If you have questions regarding the applicability of this rule to a particular entity, call the EPCRA/CAA Hotline at (800) 424-9346 (TDD: (800) 553-7672).

Category NAICS
Codes SIC
Codes Examples of Potentially Regulated

Entities

Chemical

manufacturers 325 28 Petrochemicals Industrial gas

Alkalies and chlorine Industrial inorganics Industrial organics

Plastics and resins Agricultural chemicals Soap, cleaning compounds Explosives Miscellaneous chemical manufacturing

Petroleum refineries 32411 2911 Petroleum refineries

Pulp and paper 322 26 Paper mills Pulp mills Paper products

Food processors 311 20 Dairy products Fruits and vegetables Meat products Seafood products

Polyurethane foam 32615 3086 Plastic foam pr oducts

Non-metallic mineral products 327 32 Glass and glass products Other non-metallic mineral products

Metal products 331

332 33

34 Primary metal manufacturing Fabricated metal products

April 15, 1999 viii

### Category NAICS
Codes SIC
Codes Examples of Potentially Regulated

Entities

Machinery manufacturing 333 35 Industrial machinery

Farm mac hinery Other machinery

Computer and electronic equipment 334 36 Electronic equipment

Semiconductors

Electric equipment 335 36 Lighting Appliance manufacturing Battery manufacturing

Transportation equipment 336 37 Motor vehicles and parts

Aircraft

Food distributors 4224

4228 514

518 Frozen and refrigerated f oods

Beer and wines

Chemical distributors 42269 5169 Chemical w holesalers

Farm supplies 42291 5191 Agricultural retailers and w holesalers

Propane dealers 454312 5171

5984 Propane retailers and w holesalers

Warehouses 4931 422 Refrigerated ware houses Warehouse storing chemicals

Water treatment 22131 4941 Dr inking water treatment systems

Wastewater treatment 22132

56221 4952

4933 Sewerage systems

Wastewater treatment

Waste treatment

Electric utilities 22111 4911 Electric power generation

Propane users Manufacturing facilities Large institutions

Commercial fac ilities

Federal facilities Military installations Department of Energy installations

April 15, 1999 ixRoadmap to Offsite Consequence Analysis Guidance by Type of ChemicalType of Chemical and Release ScenarioApplicable Sections and AppendicesToxic GasWorst-Case Scenario1) Define Worst CaseSection 2.12) Select Scenario3) Calculate Release RatesSections 2.2 and 2.3UnmitigatedSection 3.1.1Passive MitigationSection 3.1.2RefrigeratedSection 3.1.34) Find Toxic EndpointAppendix B (Exhibit B-1)5) Determine Reference Table and DistanceSection 3.1.3, 3.2.3Dense or Neutrally Buoyant PlumeChapter 4 and Appendix B (Exhibit B-1)Chemical-Specific Tables (ammonia, chlorine, sulfur dioxide)Chapter 4Urban or RuralSection 2.1 and Chapter 4Release DurationSection 2.1Alternative Scenario1) Define Alternative ScenarioChapter 62) Select Scenario3) Calculate Release RatesChapter 6Unmitigated (from tanks and pipes)Section 7.1.1Active or Passive MitigationSection 7.1.24) Find Toxic Endpoint5) Determine Reference Table and DistanceAppendix B (Exhibit B-1)Dense or Neutrally Buoyant PlumeChapter 8 and Appendix B (Exhibit B-1)Chemical-Specific Tables (ammonia, chlorine, sulfur dioxide)Chapter 8Urban or RuralSection 2.1 and Chapter 8Release DurationSection 7.1April 15, 1999xRoadmap to Offsite Consequence Analysis Guidance by Type of Chemical (continued)Type of Chemical and Release ScenarioApplicable Sections and AppendicesToxic LiquidWorst-Case Scenario1) Define Worst CaseSection 2.12) Select Scenario3) Calculate Release RatesSections 2.2 and 2.3Releases from PipesSection 3.2.1Unmitigated Pool EvaporationSection 3.2.2Passive Mitigation (dikes, buildings)Section 3.2.3Release at Ambient TemperatureSection 3.2.2, 3.2.3Release at Elevated TemperatureSection 3.2.2, 3.2.3Releases of MixturesSection 3.2.4 and Appendix B (Section B.2)Temperature Corrections for Liquids at 25-50 CoSection 3.2.5 and Appendix B (Exhibit B-4)Releases of Solutions4) Find Toxic EndpointSection 3.3 and Appendix B (Exhibit B-3)For Liquids/MixturesAppendix B (Exhibit B-2)For Solutions5) Determine Reference Table and DistanceAppendix B (Exhibit B-3)Dense or Neutrally Buoyant Plume (liquids)Chapter 4 and Appendix B (Exhibit B-2)Dense or Neutrally Buoyant Plume (solutions)Chapter 4 and Appendix B (Exhibit B-3)Chemical Specific Table (aqueous ammonia)Chapter 4Urban or RuralSection 2.1 and Chapter 4Release Duration (liquids)Section 3.2.2Release Duration (solutions)Chapter 4April 15, 1999xiRoadmap to Offsite Consequence Analysis Guidance by Type of Chemical (continued)Type of Chemical and Release ScenarioApplicable Sections and AppendicesToxic LiquidAlternative Scenario1) Define Alternative ScenarioChapter 62) Select ScenarioChapter 63) Calculate Release RatesSection 7.2Unmitigated (from tanks and pipes)Section 7.2.1Active or Passive MitigationSection 7.2.2Release at Ambient TemperatureSection 7.2.3Release at Elevated TemperatureSection 7.2.3Release of Solution4) Find Toxic EndpointSections 7.2.4 and 3.3 and Appendix B (Exhibit B-3)For Liquids/MixturesAppendix B (Exhibit B-2)For Solutions5) Determine Reference Table and DistanceAppendix B (Exhibit B-3)Dense or Neutrally Buoyant Plume (liquids/mixtures)Chapter 8 and Appendix B (Exhibit B-2)Dense or Neutrally Buoyant Plume (solutions)Chapter 8 and Appendix B (Exhibit B-3)Chemical-Specific Table (aqueous ammonia)Chapter 8Urban or RuralSection 2.1 and Chapter 8Release Duration (liquids/mixtures)Section 7.2Release Duration (solutions)Chapter 8April 15, 1999xiiRoadmap to Offsite Consequence Analysis Guidance by Type of Chemical (continued)Type of Chemical and Release ScenarioApplicable Sections and AppendicesFlammable SubstanceWorst-Case Scenario1) Define Worst CaseSections 5.1 and 2.12) Select Scenario3) Determine Distance to Overpressure EndpointSections 5.1, 2.2, and 2.3For Pure Flammable SubstancesSection 5.1For Flammable MixturesSection 5.2Alternative Scenario1) Define Alternative ScenarioChapter 62) Select Scenario3) For Vapor Cloud FiresChapter 6Calculate Release Rates (gases)Section 9.1 and Appendix C (Exhibit C-2)Calculate Release Rates (liquids)Section 9.2 and Appendix C (Exhibit C-3)Find Lower Flammability Limit (gases)Appendix C (Exhibit C-2)Find Lower Flammability Limit (liquids)Appendix C (Exhibit C-3)Dense or Neutrally Buoyant (gases)Appendix C (Exhibit C-2)Dense or Neutrally Buoyant (liquids)Appendix C (Exhibit C-3)Urban or RuralSection 10.1Release DurationSection 10.1Determine DistanceSection 10.14) For Pool FiresSection 10.2 and Appendix C (Exhibit C-3)5) For BLEVEsSection 10.36) For Vapor Cloud ExplosionsSection 10.4April 15, 1999xiii

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April 15, 1999 xiv

## 1 INTRODUCTION

1.1 Purpose of this Guidance

This document provides guidance on how to conduct the offsite consequence analyses for

Risk Management Programs required under the Clean Air Act (CAA). Section 112(r)(7) of the CAA

directed the U.S. Environmental Protection Agency (EPA) to issue regulations requiring facilities

with large quantities of very hazardous chemicals to prepare and implement programs to prevent the

accidental release of those chemicals and to mitigate the consequences of any releases that do occur. EPA issued that rule, “Chemical Accident Prevention Provisions” on June 20, 1996. The rule is

codified at part 68 of Title 40 of the Code of Federal Regulations (CFR). If you handle, manufacture,

use, or store any of the toxic or flammable substances listed in 40 CFR 68.130 above the specified

threshold quantities in a process, you are required to develop and implement a risk management

program under part 68 of 40 CFR. The rule applies to a wide variety of facilities that handle, manufacture, store, or use toxic substances, including chlorine and ammonia, and highly flammable substances, such as propane. If you are not sure whether you are subject to the rule, you should

review the rule and Chapters 1 and 2 of EPA’s General Guidance for Risk Management Programs (40 CFR part 68), available from EPA at www.epa.gov/emergencies/rmp

.

If you are subject to the rule, you are required to conduct an offsite consequence analysis to provide information to the state, local, and federal governments and the public about the potential

consequences of an accidental chemical release. The offsite consequence analysis consists of two
elements:



### � A worst­case release scenario, and



### � Alternative release scenarios.

To simplify the analysis and ensure comparability, EPA has defined the worst­case scenario

as the release of the largest quantity of a regulated substance from a single vessel or process line

failure that results in the greatest distance to an endpoint. In broad terms, the distance to the endpoint

is the distance a toxic vapor cloud, heat from a fire, or blast waves from an explosion will travel

before dissipating to the point that serious injuries from short­term exposures will no longer occur. Endpoints for regulated substances are specified in 40 CFR 68.22(a) and Appendix A of part 68 and

are presented in Appendices B and C of this guidance.

Alternative release scenarios are scenarios that are more likely to occur than the worst­case
scenario and that will reach an endpoint offsite, unless no such scenario exists. Within these two
parameters, you have flexibility to choose alternative release scenarios that are appropriate for your site. The rule, in 40 CFR 68.28 (b)(2), and the General Guidance for Risk Management Programs (40

CFR part 68)

, Chapter 4, provide examples of alternative release scenarios that you should consider

when conducting the offsite consequence analysis.

March 2009Chapter 1
Introduction



### RMP*CompTM

To assist those using this guidance, the National Oceanic and Atmospheric Administration (NOAA) and EPA have developed a software program, RMP*CompTM, that performs the
calculations described in this document. This software can be downloaded from the

EPA/OE M website at www.epa.gov/emergen ci es/rmp.

This guidance document provides a simple methodology for conducting offsite consequence analyses. You may use simple equations to estimate release rates and reference tables to determine distances to the endpoint of concern. This guidance provides generic reference tables of distances, applicable to most of the regulated toxic substa nces, and chemical-specific tables for ammonia, chlorine, and sulfur dioxide. This guidance also provides reference tables of distances for consequences of fires and explosions of flammable substances. In some cases, the rule allows users of this document to adopt generic assumptions rather than the site-specific data required if another model is employed (see Exhibit 1).

The methodology and reference tables of dist ances presented here are optional. You are not required to use this guidance. You may use publicly available or proprietary air dispersion models to do your offsite consequence analysis, subject to certain conditions. If you choose to use models instead of this guidance, you should review the rule and Chapter 4 of the General Guidance for Risk Management Programs, which outline required conditions for use of models. In selected example analyses, this document presents the results of some models to provide a basis for comparison. It also indicates certain conditions of a release that may warrant more sophisticated modeling than is represented here. However, this guidance does not discuss the procedures to follow when using models; if you choose to use models, you should consult the appropriate references or instructions for
those models.

This guidance provides distances to endpoints for toxic substances that range from 0.1 miles to 25 miles. Other models may not project distances this far (and some may project even longer distances). One commonly used model, ALOHA, has an artificial distance cutoff of 6 miles (i.e., any scenario which would result in an endpoint distance beyond 6 miles is reported as “greater than 6 miles”). Although you may use ALOHA if it is approp riate for the substance and scenario, you should consider choosing a different mode l if the scenario would normally result in an endpoint distance significantly greater than 6 miles. Otherwise, you should be prepared to explain the difference between your results and those in this guidance or other commonly used models. Also, you should be aware that the RMP*eSubmit system accepts only numerical entries (i.e., it will not accept a “greater than” distance). If you do enter a distance in RMP*eSubmit that is the result of a particular model’s maximum distance cutoff (including the maximum distance cutoff in this guidance), you can explain this in the executive summary of your RMP.

March 2009 1 - 2Exhibit 1 Required Parameters for Modeling (40 CFR 68.22)

WORST CASE ALTERNATIVE SCENARIO

Endpoints (§68.22(a))

Endpoints for toxic substances are specified in part 68 Appendix A. Endpoints for toxic substances are specified in part 68 Appe ndix A.

For flammable substances, endpoint is overpressure of 1 pound per square inch (psi) for vapor cloud explosions. For flammable substances, endpoint is:
� Overpressure of 1 psi for vapor cloud explosions, or
� Radiant heat level of 5 kilowatts per square meter (kW/m ) for 40 2 seconds for heat from fires (or equivalent dose), or
� Lower flammability limit (LFL) as specified in NFPA documents or other generally recognized sources.

Wind speed/stability ( §68.22(b))

This guidance assumes 1.5 meters per second and F stability. For other models, use wind speed of 1.5 meters per second and F stability class unless you can demonstrate that local meteorological data applicable to the site show a higher minimum wind speed or less stable atmosphere at all times during the previous three years. If you can so demonstrate, these minimums may be used for site-specific modeling. This guidance assumes wind speed of 3 meters per second and D stability. For other models, you must use typical meteoro logical conditions for your site.

Ambient temperature/humidity (§68.22(c))

This guidance assumes 25 � C (77 � F) and 50 percent humidity. For other models for toxic substances, you must use the highest daily maximum temperature and average humidity for the site during the past three years. This guidance assumes 25 � C and 50 percent humidity. For other models, you may use average temperature/humidity data gather ed at the site or at a local meteorological station.

Height of release (§68.22(d))

For toxic substances, you must assume a ground level release. This guidance assumes a ground-level release. For other models, release height may be determined by the release scenario.

Surface roughness (§68.22(e))

Use urban (obstructed terrain) or rural (flat terrain) topography, as appropriate. Use urban (obstructed terrain) or rural (flat terrain) topography, as appropriate.

Dense or neutrally buoyant gases (§68.22(f))

Tables or models used for dispersion of regulated toxic substances must appropriately account for gas density. If you use this guidance, see Tables 1-4 for neutrally buoyant gases and Tables 5-8 for dense gases, or Tables 9-12 for specific chemicals. Tables or models used for dispersion must appropriately account for gas density. If you use this guidance, see Tables 14-1 7 for neutrally buoyant gases and Tables 18-21 for dense gases, or Tab les 22-25 for specific chemicals.

Temperature of released substance (§68.22(g))

You must consider liquids (other than gases liquefied by refrigeration) to be released at the highest daily maximum temperature, from data for the previous three years, or at process temperature, whichever is higher. Assume gases liquefied by refrigeration at atmospheric pressure to be released at their boiling points. This guidance provides factors for

estimation of release rates at 25 � C or the boiling point of the released substance, and also provides temperature correction factors. Substances may be considered to be released at a proc ess or ambient temperature that is appropriate for the scenario. This guidance provides factors for estimation of release rates at 25 � C or the boiling point of the released substance, and also provides tempera ture
correction factors.

April 15, 1999 1 - 3Chapter 1

Introduction



### 1.2 This Guidance Compared to Other Models

Results obtained using the methods in this document are expected to be conservative (i.e., they will generally, but not always, overestimate the distance to endpoints). The chemical-specific reference tables in this guidance provide less conservative results than the generic reference tables, because the chemical-specific tables were derived using more realistic assumptions and considering more factors.

Complex models that can account for many site-specific factors may give less conservative estimates of offsite consequences than the simple methods in this guidance. This is particularly true for alternative scenarios, for which EPA has not specified many assumptions. However, complex models may be expensive and require considerable expertise to use; this guidance is designed to be simple and straightforward. You will need to consider these tradeoffs in deciding how to c arry out your required consequence analyses. Appendix A provides information on references for some other methods of analysis; these references do not include all models that you may use for these analyses. You will find that modeling results will sometimes vary considerably from model to model.



### 1.3 Number of Scenarios to Analyze

The number and type of analyses you must perform depend on the “Program” level of each of your processes. The rule defines three Program levels. Processes are eligible for Program 1 if, among other criteria, there are no public receptors within the distance to the endpoint for the worst-case scenario. Because no public receptors would be affected by the worst-case release, no further modeling is required for these processes. For processes subject to Program 2 or Program 3, both worst-case release scenarios and alternative release scenarios are required. To determine the Program level of your processes, consult 40 CFR 68.10(b), (c), and (d), or Chapter 2 of EPA’s General Guidance for Risk Management Programs (40 CFR part 68)

.

Once you have determined the Program level of your processes, you are required to conduct the following offsite consequence analyses:

� One worst-case release scenario for each Program 1 process;

� One worst-case release scenario to represent all regulated toxic su bstances in Program 2 and Program 3 processes;

� One worst-case release scenario to represent all regulated flammable su bstances in Program 2 and Program 3 processes;

� One alternative release scenario for each regulated toxic su bstance in Program 2 and Program 3 processes; and

� One alternative release scenario to represent all regulated flammable su bstances in Program 2 and Program 3 processes.

NOTE: You may need to analyze additional worst-case scenarios if release scenarios for regulated flammable or toxic substances from other covered processes at your fac ility would affect different public

April 15, 1999 1 - 4Chapter 1
Introduction

receptors. For example, worst-case release scenarios fo r storage tanks at opposite ends of your facility may potentially reach different areas where people could be affected. In that case, you will have to conduct analyses of and report on both releases.



### GUIDANCE FOR INDUSTRY-SPECIFI C RISK MANAGEMENT PROGRAMS

EPA developed guidance for industry-specific risk management programs for the following industries:

Ø Propane storage Ø Warehouses
facilities Ø Ammonia refrigeration
Ø Chemical distributors Ø Small propane retailers &
Ø Waste water treatment users plants Industry-specific guidance is either appended to this guidance or is contained in stand-alone documents that you can obtain from EPA's website at www.epa.gov/emergencies/rmp. If an industry-specific appendix or guidance document exists for your process(es), you should consider using it because it will provide more information that is specific to your process(es), including dispersion modeling and prevention program elements.



### 1.4 Modeling Issues

The consequences of an accidental chemical release depend on the conditions of the release

and the conditions at the site at the time of the re lease. This guidance provides reference tables of distances, based on results of modeling, for estimation of worst-case and alternative scenario consequence distances. Worst-case consequence distan ces obtained using these tables are not intended to be precise predictions of the exact distances th at might be reached in the event of an actual accidental release. For this guidance, worst-case distances are based on modeling results assuming the combination of worst-case conditions required by the rule. This combination of conditions occurs rarely and is unlikely to persist for very long. To derive the alternative scenario distances, less conservative assumptions were used for modeling; these assumptions were chosen to represent more likely conditions than the worst-cas e assumptions. Nevertheless, in an actual accidental release, the conditions may be very different. Users of this guidance should remember that the results derived from the methods presented here are rough estimates of potential consequence distances. Other models may give different results; the same model also may give different results if different assumptions about release conditions and/or site conditions are used.

The reference tables of distances in this guidance provide results to a maximum distance of 25 miles. EPA recognizes that modeling results at su ch large distances are highly uncertain. Almost no experimental data or data from accidents are available at such large distances to compare to modeling results. Most data are reported for distances well under 10 miles. Modeling uncertainties are likely to increase as distances increase because conditions (e.g., atmospheric stability, wind speed, surface roughness) are not likely to remain constant over larg e distances. Thus, at large distances (e.g., greater than about 6 to 10 miles), the modeling results should be viewed as very coarse estimates of consequence distances. EPA believes,

March 2009 1 - 5Chapter 1

Introduction

however, that the results, even at large distances, can provide useful information for comparison purposes. For example, Local Emergency Planning Committees (LEPCs) and other local agencies can use relative differences in distance to aid in establishing chemical accident prevention and preparedness priorities among facilities in a community. Since worst-case scenario distances are based on modeling conditions that are unlikely to occur, and since modeling of any scenario that results in large distances is very uncertain, EPA strongly urges communities and industry not to rely on the results of worst-case modeling or any modeling that results in very large toxic endpoint distances in emergency pla nning and response activities. Results of alternative scenario models are apt to provide a more reasonable basis for planning and response.



### 1.5 Steps for Performing the Analysis

This Chapter presents the steps you should follow in using this guidance to c arry out an offsite consequence analysis. Before carry ing out one or more worst-case and/or alternative release analyses, you will need to obtain several pi eces of informat ion about the regulated su bstances you have, the area surrounding your site, and typical meteorological conditions:

� Determine whether each regulated su bstance is toxic or flammable, as indicated in the rule or Appendices B and C of this guidance.

� For the worst-case analysis, determine the quantity of each substance held in the largest single vessel or pipe.

� Collect information about any passive or active (alternative scenarios only) release mitigation measures that are in place for each su bstance.

� For toxic substances, determine whether the substance is stored as a gas, as a liq uid, as a gas liquefied by refrigeration, or as a gas liquefied under pressure. For alternative scenarios involving a vapor cloud fire, you may also need this information for flammable su bstances.

� For toxic liquids, determine the highest daily maximum temperature of the liquid, based on data for the previous three years, or process temperature, whichever is higher.

� For toxic substances, determine whether the substance behaves as a dense or neutrally buoyant gas or vapor (see Appendix B, Exhibits B-1 and B-2). For alternative scenarios involving a vapor cloud fire, you will also need this information for flammable su bstances (see Appendix C, Exhibits C-2 and C-3).

� For toxic substances, determine whether the topography (su rface roughness) of your site is either urban or rural as thse terms are defined by the rule (see 40 CFR 68.22(e)). For alternative scenarios involving a vapor cloud fire, you will also need this information for

flammable substances.

After you have gathered the above information, you will need to take three steps (except for flammable worst-case releases):

(1) Select a scenario;

April 15, 1999 1 - 6Chapter 1

Introduction

(2) Determine the release or volatilization rate; and (3) Determine the distance to the endpoint.

For flammable worst-case scenarios, only steps one and three are needed. Sections 1.5.1 through 1.5.6 outline the procedures to perform the analyses. In addition to basic procedures, these sections provide references to sections of this guidance where you will find detailed instructions on c arry ing out the applicable portion of the analysis. Sections 1.5.1 through 1.5.3 below provide basic steps to analyze worst-case scenarios for toxic gases, toxic liquids, and flammable su bstances. Sect ions 1.5.4 through 1.5.6 provide basic steps for alternative scenario analysis. Appendix E of this document provides worksheets that may help you to perform the analyses.



### 1.5.1 Worst-Case Analysis for Toxic Gases

To conduct worst-case analyses for toxic gases, including toxic gases liquefied by pressurization (see Appendix E, Worksheet 1, for a worksheet that can be used in c arry ing out this analysis):

Step 1 : Determine worst-case scenario . Identify the toxic gas, quantity, and worst-case release scenario, as defined by the rule (Chapter 2).

Step 2 : Determine release rate . Estimate the release rate for the toxic gas, using the p arameters required by the rule. This guidance provides methods for estimating the release rate for:

� Unmitigated releases (Section 3.1.1).

� Releases with passive mitigation (Section 3.1.2).

Step 3 : Determine distance to endpoint . Estimate the worst-case consequence distance based on the release rate and toxic endpoint (defined by the rule) (Chapter 4). This guidance provides reference tables of distances (Reference Tables 1-12). Select the appropriate reference table based on the density of the released substance, the topography of your site, and the durat ion of the release (always 10 minutes for gas releases). Estimate distance to the endpoint from the appropriate table.



### 1.5.2 Worst-Case Analysis for Toxic Liquids

To conduct worst-case analyses for toxic su bstances that are liq uids at ambient conditions or for toxic gases that are liquefied by refrigeration alone (see Appendix E, Worksheet 2, for a worksheet for this analysis):

Step 1 : Determine worst-case scenario . Identify the toxic liquid, quantity, and worst-case release scenario, as defined by the rule (Chapter 2). To estimate the quantity of liquid released from piping, see Section

3.2.1.

Step 2 : Determine release rate . Estimate the volatilization rate for the toxic liquid and the duration of the release, using the parameters required by the rule. This guidance provides methods for estimating the pool evaporation rate for:

April 15, 1999 1 - 7Chapter 1

Introduction

� Gases liquefied by refrigeration alone (Sections 3.1.3 and 3.2.3).

� Unmitigated releases (Section 3.2.2).

� Releases with passive mitigation (Section 3.2.3).

� Releases at ambient or elevated temperature (Sections 3.2.2, 3.2.3, and 3.2.5).

� Releases of mixtures of toxic liquids (Section 3.2.4).

� Releases of common water solutions of regulated su bstances and of oleum (Sect ion 3.3).

Step 3 : Determine distance to endpoint . Estimate the worst-case consequence distance based on the release rate and toxic endpoint (defined by the rule) (Chapter 4). This guidance provides reference tables of distances (Reference Tables 1-12). Select the appropriate reference table based on the density of the released substance, the topography of your site, and the durat ion of the release. Estimate distance to the endpoint from the appropriate table.



### 1.5.3 Worst-Case Analysis for Flammable Substances

To conduct worst-case analyses for all regulated flammable su bstances (i.e., gases and liq uids) (see Appendix E, Worksheet 3, for a worksheet for this analysis):

Step 1 : Determine worst-case scenario . Identify the appropriate flammable substance, quantity, and worstcase scenario, as defined by the rule (Chapter 2).

Step 2 : Determine distance to endpoint . Estimate the distance to the required overpressure endpoint of 1 psi for a vapor cloud explosion of the flammable su bstance, us ing the assumptions required by the rule(Chapter 5). This guidance provides a reference table of distances (Reference Table 13) for worstcase vapor cloud explosions. Estimate the distance to the endpoint from the quantity released and the

table.



### 1.5.4 Alternative Scenario Analysis for Toxic Gases

To conduct alternative release scenario analyses for toxic gases, including toxic gases liquefied by pressurization (see Appendix E, Worksheet 4, for a worksheet for this analysis):

Step 1 : Select alternative scenario . Choose an appropriate alternative release scenario for the toxic gas. This scenario should have the potential for offsite impacts unless no such scenario exi sts. (Chapter 6).

Step 2 : Determine release rate . Estimate the release rate and duration of the release of the toxic gas, based on your scenario and site-specific conditions. This guidance provides methods for:

� Unmitigated releases (Section 7.1.1).

� Releases with active or passive mitigation (Section 7.1.2).

April 15, 1999 1 - 8Chapter 1

Introduction

Step 3 : Determine distance to endpoint . Estimate the alternative scenario distance based on the release rate and toxic endpoint (Chapter 8). This guidance provides reference tables of distances (Reference Tables 14-25) for alternative scenarios for toxic substances. Select the appropriate reference table based on the density of the released substance, the topography of your site, and the durat ion of the release. Estimate distance to the endpoint from the appropriate table.



### 1.5.5 Alternative Scenario Analysis for Toxic Liquids

To conduct alternative release scenario analyses for toxic su bstances that are liq uids at ambient conditions or for toxic gases that are liquefied by refrigeration alone (see Appendix E, Worksheet 5, for a worksheet for this analysis):

Step 1 : Select alternative scenario . Choose an appropriate alternative release scenario and release quantity for the toxic liquid. This scenario should have the potential for offsite impacts (Chapter 6), unless no

such scenario exists.

Step 2 : Determine release rate . Estimate the release rate and duration of the release of the toxic liquid, based on your scenario and site-specific conditions. This guidance provides methods to estimate the liquid release rate and quantity of liquid released for:

� Unmitigated liquid releases (Section 7.2.1).

� Mitigated liquid releases (Section 7.2.2).

The released liquid is assumed to form a pool. This guidance provides methods to estimate the pool evaporation rate and release duration for:

� Unmitigated releases (Section 7.2.3).

� Releases with passive or active mitigation (Section 7.2.3).

� Releases at ambient or elevated temperature (Sections 7.2.3).

� Releases of common water solutions of regulated su bstances and of oleum (Sect ion 7.2.4).

Step 3 : Determine distance to endpoint . Estimate the alternative scenario distance based on the release rate and toxic endpoint (Chapter 8). This guidance provides reference tables of distances (Reference Tables 14-25) for alternative scenarios for toxic substances. Select the appropriate reference table based on the density of the released substance, the topography of your site, and the durat ion of the release. Estimate distance to the endpoint from the appropriate table.



### 1.5.6 Alternative Scenario Analysis for Flammable Substances

To conduct alternative release scenario analyses for all regulated flammable su bstances (i.e., gases and liquids) (see Appendix E, Worksheet 6, for a worksheet for this analysis):

April 15, 1999 1 - 9Chapter 1
Introduction



### Step 1: Select alternative scenario . Identify the flammable substance, and choose the quantity and type of event for the alternative scenar io consequence analysis (Chapter 6).

Step 2: Determine release rate . Estimate the release rate to air of the flammable gas or liquid, if the scenario involves a vapor cloud fire (Secti on 9.1 for flammable gases, Section 9.2 for flammable liquids).

Step 3: Determine distance to endpoint . Estimate the distance to the appropriate endpoint (defined by the rule). This guidance provides methods for:

• 

### Vapor cloud fires (Section 10.1 and Reference Tables 26-29); select the appropriate reference table based on the density of the re leased substance and the topography of your site, and estimate distance to the end point from the appropriate table.

• 

### Pool fires (Section 10.2); estimate distance from the equation and chemical-specific factors provided.

• 

### BLEVEs (Section 10.3 and Reference Table 30) ; estimate distance from the quantity of
flammable substance and the table.

• 

### Vapor cloud explosions (Section 10.4 and Refe rence Table 13); estimate quantity in the cloud from the equation and chemical-specific factors provided, and estimate distance from the quantity, the table, and a factor provided for alternative scenarios.

1.6 Additional Sources of Information

EPA’s risk management program requireme nts may be found at 40 CFR part 68. The relevant sections were published in the Federal Register on Janua ry 31, 1994 (59 FR 4478) and June 20, 1996 (61 FR 31667). Final rules amending the list of substances and thresholds were published on August 25, 1997 (62 FR 45130) and Ja nuary 6, 1998 (63 FR 640). A consolidated copy of these regulations is available in Appendix F.

EPA is working with industry and local, stat e, and federal government agencies to assist sources in complying with these requirements. Fo r more information, refer to the General Guidance for Risk Management Programs Appe ndix E (Technical Assistance). Appendices C and D of the General Guidance also provide points of contact for EPA and Occupational Safety and Health Administration (OSHA) at the state and fe deral levels for your qu estions. Your LEPC also
can be a valuable resource.

Finally, if you have access to the Internet, EPA has made copies of the rules, fact sheets,
and other related materials available from EPA’s website at www.epa.gov/emergencies/rmp 

### . Please check the site regularly, as additional materials ar e posted when they become available. If you do not have access to the Internet, you can call EPA’s hotline at (800) 424-9346.

March 2009 1 - 10

## 2 DETERMINING WORST-CASE SCENARIOS

In Chapter 2

� 2.1 EPA’s definition of a worst-case scenario.

� 2.2 How to determine the quantity released.

� 2.3 How to identify the appropriate worst-case scenario.



### 2.1 Definition of Worst-Case Scenario

A worst-case release is defined as:

The release of the largest quantity of a regulated su bstance from a vessel or process line failure, and �

The release that results in the greatest distance to the endpoint for the regulated toxic or

flammable substance. �

You may take administrative controls into account when determining the largest quantity. Administrative controls are written procedures that limit the quantity of a substance that can be stored or processed in a vessel or pipe at any one time or, alternatively, procedures that allow the vessel or pipe to occasionally store larger than usual quantities (e.g., during shutdown or turnaround). Endpoints for regulated substances are specified in the rule (40 CFR 68.22(a), and Appe ndix A to part 68 for toxic su bstances). For the worst-case analysis, you do not need to consider the possible causes of the worst-case release or the probability that such a release might occur; the release is simply assumed to take place. You must assume all releases take place at ground level for the worst-case analysis.

This guidance assumes meteorological conditions for the worst-case scenario of atmospheric stability class F (stable atmosphere) and wind speed 1.5 meters per second (3.4 miles per hour). Ambient air

o o temperature for this guidance is 25 C (77 F). If you use this guidance, you may assume this ambient temperature for the worst case, even if the maximum temperature at your site in the last three years is higher.

The rule provides two choices for topography, urban and rural. EPA (40 CFR 68.22(e)) has defined urban as many obstacles in the immediate area, where obstacles inc lude buildings or trees. Rural, by EPA’s definition, means there are no buildings in the immediate area, and the terrain is generally flat and unobstructed. Thus, if your site is located in an area with few b uildings or other o bstruct ions (e.g., hills, trees), you should assume open (rural) conditions. If your site is in an area with many o bstruct ions, even if it is in a remote location that would not usually be considered urban, you should assume urban conditions.

Toxic Gases

o Toxic gases include all regulated toxic su bstances that are gases at ambient temperature (25 C, 77

o F), with the exception of gases liquefied by refrigeration under atmospheric pressure and released into diked areas. For the worst-case consequence analysis, you must assume that a gaseous release of the total quantity occurs in 10 minutes. You may take passive mitigation measures (e.g., enclosure) into account in the analysis

of the worst-case scenario.

April 15, 1999Chapter 2 Determining Worst-Case Scenarios

Gases liquefied by refrigeration alone and released into diked areas may be modeled as liquids at their boiling points and assumed to be released from a pool by evaporation (40 CFR 68.25(c)(2)). Gases liquefied by refrigeration alone that would form a pool one centimeter or less in depth upon release must be modeled as gases. (Modeling indicates that pools one centimeter or less deep formed by gases liquefied by refrigeration would completely evaporate in 10 minutes or less, giving a release rate that is equal to or greater than the worst-case release rate for a gaseous release. In this case, therefore, it is appropriate to treat these substances as gases for the worst-case analysis.)

Endpoints for consequence analysis for regulated toxic su bstances are specified in the rule (40 CFR part 68, Appendix A). Exhibit B-1 of Appendix B li sts the endp oint for each toxic gas. These endpoints are used for air dispersion modeling to estimate the consequence distance.

Toxic Liquids

For toxic liquids, you must assume that the total quantity in a vessel is spilled. This guidance assumes the spill takes place onto a flat, non-absorbing surface. For toxic liquids c arried in pipe lines, the quantity that might be released from the pipeline is assumed to form a pool. You may take passive mitigation systems (e.g., dikes) into account in consequence analysis. The total quantity spilled is assumed to spread instantaneously to a depth of one centimeter (0.033 foot or 0.39 inch) in an undiked area or to cover a diked area instantaneously. The temperature of the released liquid must be the highest daily maximum temperature occurring in the past three years or the temperature of the su bstance in the vessel, whichever is higher (40 CFR 68.25(d)(2)). The release rate to air is estimated as the rate of evaporat ion from the pool. If liquids at your site might be spilled onto a surface that could rapidly absorb the spilled liquid (e.g., porous soil), the methods presented in this guidance may greatly overestimate the consequences of a release. Consider using

another method in such a case.

Exhibit B-2 of Appendix B presents the endpoint for air dispersion modeling for each regulated toxic liquid (the endpoints are specified in 40 CFR part 68, Appe ndix A).

Flammable Substa nces

For all regulated flammable su bstances, you must assume that the worst-case release results in a vapor cloud containing the total quantity of the su bstance that c ould be released from a vessel or pipeline.For the worst-case consequence analysis, you must assume the vapor cloud detonates. If you use a TNTequivalent method for your analysis, you must assume a 10 percent yield factor.

The rule specifies the endpoint for the consequence analysis of a vapor cloud explosion of a regulated flammable substance as an overpressure of 1 p ound per square inch (psi). This endpoint was chosen as the threshold for potential serious injuries to people as a result of property damage caused by an explosion (e.g., injuries from flying glass from shattered windows or falling debris from damaged houses). (See Appendix D, Section D.5 for additional information on this endpoint.)

April 15, 1999 2 - 2Chapter 2 Determining Worst-Case Scenarios

Effect of Required Assum ptions

The assumptions required for the worst-case analysis are intended to provide conservative worst-case consequence distances, rather than accurate predictions of the potential consequences of a release; that is, in most cases your results will overestimate the effects of a release. In certain cases, actual conditions could be even more severe than these worst-case assumptions (e.g., very high process temperature, high process pressure, or unusual weather conditions, such as temperature inversions); in such cases, your results might underestimate the effects. However, the required assumptions generally are expected to give conservative

results.



### 2.2 Determination of Quantity for the Worst-Case Scenario

EPA has defined a worst-case release as the release of the largest quantity of a regulated su bstance from a vessel or process line failure that results in the greatest distance to a specified endpoint. For substances in vessels, you must assume release of the largest am ount in a single vessel. For su bstances in pipes, you must assume release of the largest amount in a pipe. The largest quantity should be determined taking into account administrative controls rather than absolute capacity of the vessel or pipe. Administrative controls are written procedures that limit the quantity of a substance that can be stored or processed in a vessel or pipe at any one time, or, alternatively, occasionally allow a vessel or pipe to store larger than usual quantities (e.g., during turnaround).



### 2.3 Selecting Worst-Case Scenarios

Under part 68, a worst-case release scenario analysis must be completed for all covered processes, regardless of program level. The number of worst-case scenarios you must analyze depends on several factors. You need to consider only the h azard (toxicity or flammab ility) for which a su bstance is re gulated (i.e., even if a regulated toxic su bstance is also flammable, you only need to consider toxicity in your analysis; even if a regulated flammable su bstance is also toxic, you only need to consider flammability).

For every Program 1 process, you must report the worst-case scenario with the greatest distance to an endpoint. If a Program 1 process has more than one regulated su bstance held above its thres hold, you must determine which substance pr oduces the greatest distance to its endpoint and report on that su bstance. If a Program 1 process has both regulated toxics and flammables above their thresholds, you still report only the one scenario that produces the greatest distance to the endpoint. The process is eligible for Program 1 if there are no public receptors within the distance to an endpoint of the worst-case scenario for the process and the other Program 1 criteria are met. For Program 2 or Program 3 processes, you must analyze and report on one worst-case analysis representing all toxic regulated su bstances present above the thres hold quantity and one worst-case analysis representing all flammable regulated su bstances present above the thres hold quantity. You may need to submit an additional worst-case analysis if a worst-case release from elsewhere at the source would potentially affect public receptors different from those affected by the initial worst-case scenario(s).

If you have more than one regulated su bstance in a class, the substance chosen for the consequence analysis for each hazard for Program 2 and 3 processes s hould be the su bstance that has the potential to cause the greatest offsite consequences. Choosing the toxic regulated su bstance that m ight lead to the greatest offsite consequences may require a screening analysis of the toxic regulated su bstances on site, because the potential consequences are dependent on a number of factors, including quantity, toxicity, and volatility.

April 15, 1999 2 - 3Chapter 2 Determining Worst-Case Scenarios

Location (distance to the fenceline) and conditions of processing or storage (e.g., a high temperature process) also should be considered. In selecting the worst-case scenario, you may want to consider the following points:

Toxic gases with low toxic endpoints are likely to give the greatest distances to the endpoint for a given release quantity; a toxic gas would be a likely choice for the worst-case analysis required for Program 2 and 3 processes (processes containing toxic gases are unlikely to be eligible for Program 1). �

Volatile, highly toxic liquids (i.e., liquids with high ambient vapor pressure and low toxic endpoints) also are likely to give large distances to the endpoint (processes containing this type of substance are unlikely to be eligible for Program 1). �

Toxic liquids with relatively low volatility (low vapor pressure) and low toxicity (large toxic endpoint) in ambient temperature processes may give fairly small distances to the endpoint; you probably would not choose such su bstances for the worst-case analysis for Program 2 or 3 if you have other regulated toxics, but you may want to consider c arry ing out a worst-case analysis to demonstrate potential Program 1 eligibility. �

For flammable substances, you must consider the consequences of a vapor c loud explosion in the analysis. The severity of the consequences of a vapor cloud explosion depends on the quantity of the released substance in the vapor c loud, its heat of combustion, and other factors that are assumed to be the same for all flammable substances. In most cases, the analysis probably s hould be based on the regulated flammable substance present in the greatest quantity; however, a substance with a high heat of combustion may have a greater potential offsite impact than a larger quantity of a substance with a lower heat of combust ion. In some cases, a regulated flammable su bstance that is close to the fence line might have a greater potential offsite impact than a larger quantity farther from the fence line.

You are likely to estimate smaller worst-case distances for flammable su bstances than for similar quantities of most toxic substances. Because the distance to the endp oint may be relatively small, you may

find it worthwhile to c arry out a worst-case analysis for each process conta ining flammable su bstances to demonstrate potential eligibility for Program 1, unless there are public r eceptors close to the process.

April 15, 1999 2 - 4

## 3 RELEASE RATES FOR TOXIC SUBSTANCES

In Chapter 3

� 3.1 Estimation of worst-case release rates for toxic gases.

� 3.2 Estimation of release rates for toxic liquids evaporating from pools.

� 3.3 Estimation of release rates for common water solutions of toxic substances

and for oleum.

This chapter describes simple methods for estimating release rates for regulated toxic su bstances for the worst-case scenario. Simple release rate equations are provided, and factors to be used in these equations are provided (in Appendix B) for each regulated su bstance. The estimated release rates may be used to estimate dispersion distances to the toxic endpoint for regulated toxic gases and liquids, as discussed in Chapter 4.



### 3.1 Release Rates for Toxic Gases

In Section 3.1

� 3.1.1 Method to estimate worst-case release rates for unmitigated releases (releases directly to the air) of toxic gas.

� 3.1.2 Method to estimate worst-case release rates for toxic gas in enclosures (passive mitigation).

� 3.1.3 Method to estimate worst-case release rates for liquefied refrigerated toxic gases in diked areas (as toxic liquid - see Section 3.2.3), including

consideration of the duration of the release.

o o Regulated su bstances that are gases at ambient temperature (25 C, 77 F) s hould be considered gases for consequence analysis, with the exception of gases liquefied by refrigeration at atmospheric pressure. Gases liquefied under pressure should be treated as gases. Gases liquefied by refrigeration alone and released into diked areas may be treated as liquids at their boiling points if they would form a pool upon release that is more than one centimeter (0.033 foot) in depth. Gases liquefied by refrigerat ion alone that would form a pool one centimeter (0.033 foot) or less in depth s hould be treated as gases. Modeling shows that the evaporation rate from such a pool would be equal to or greater than the rate for a toxic gas, which is assumed to be released over 10 minutes; therefore, treating liquefied refrigerated gases as gases rather than liquids in such cases is reasonable. You may consider passive mitigation for gaseous releases and releases of gases liquefied by refrigeration.

April 15, 1999Chapter 3

Release Rates for Toxic Substances



### 3.1.1 Unmitigated Releases of Toxic Gas

If no passive mitigation system is in place, estimate the release rate for the release over a 10-minute period of the largest quantity resulting from a pipe or vessel failure, as required by the rule (40 CFR 68.25(c)). For a release from a vessel, calculate the release rate as follows:



### QS

� QR (3-1) 10

where: QR = Release rate (pounds per minute) QS = Quantity released (pounds)

Example 1. Gas Release (Diborane)

You have a tank containing 2,500 p ounds of diborane gas. Assuming the total quantity in the tank is released over a 10-minute period, the release rate (QR), from Equation 3-1, is:

QR = 2,500 p ounds/10 minutes = 250 p ounds per minute



### 3.1.2 Releases of Toxic Gas in Enclosed Space

If a gas is released in an enclosure such as a building or shed, the release rate to the outside air may be lessened considerably. The dynamics of this type of release are complex; however, you may use the simplified method presented here to estimate an approximate release rate to the outside air from a release in an enclosed space. The mitigation factor (i.e., 55 percent) presented in this method assumes that the release occurs in a fully enclosed, non-airtight space that is directly adjacent to the outside air. If you are modeling a release in an interior room that is enclosed within a building, a smaller factor (i.e., more mitigation) may be appropriate. On the other hand, a larger factor (i.e., less mitigation) should be used for a space that has doors or windows that could be open during a release. If any of these special circumstances apply to your site, you may want to consider performing site-specific modeling to determine the appropriate amount of passive mitigation. In addition, you should not incorporate the passive mitigation effect of building enclosures into your modeling if you have reason to believe the enclosure would not withstand the force of the release or if the chemical is handled outside the building (e.g., moved from one building to another building).

For the worst case, assume as before that the largest quantity resulting from a pipe or vessel failure is released over a 10-minute period. Determine the unmitigated worst-case scenario release rate of the gas as the quantity released divided by 10 (Equation 3-1). The release rate from the building will be approximately 55 percent of the worst-case scenario release rate (see Appendix D, Section D.1.2 for the derivation of this factor). Estimate the mitigated release rate as follows:

April 15, 1999 3 - 2Chapter 3

Release Rates for Toxic Substances



### QS QR × 0.55 (3-2) � 10

where: QR = Release rate (pounds per minute) QS = Quantity released (pounds)

0.55 = Mitigation factor (discussed in Appendix D, Section D.1.2)

Example 2. Gas Release in Enclosure (Diborane)

Suppose the diborane gas from Example 1 is released inside a building at the rate of 250 p ounds per minute. The mitigated release to the outside air from the building would be:

QR = 250 p ounds/minute × 0.55 = 138 p ounds per minute



### 3.1.3 Releases of Liquefied Refrigerated Toxic Gas in Diked Area

If you have a toxic gas that is liquefied by refrigeration alone, and it will be released into an area where it will be contained by dikes to form a pool more than one centimeter (0. 033 foot) in depth, you may carry out the worst-case analysis assum ing evaporation from a liquid pool at the boiling point of the liquid. If your gas liquefied by refrigeration would form a pool one centimeter (0. 033 foot) or less in depth, use the methods described in Section 3.1.1 or 3.1.2 above for the analysis. For a release in a diked area, first compare the diked area to the maximum area of the pool that could be formed. You can use Equation 3-6 in Section 3.2.3 to estimate the maximum size of the pool. Density factors (DF), needed for Equation 3-6, for toxic gases at their boiling points are listed in Exhibit B-1 of Appendix B. If the pool formed by the released liquid would be smaller than the diked area, assume a 10-minute gaseous release, and estimate the release rate as described in Section 3.1.1. If the dikes prevent the liquid from spreading out to form a pool of maximum size (one centimeter in depth), you may use the method described in Section 3.2.3 for mitigated liquid releases to estimate a release rate from a pool at the boiling point of the released su bstance. Use Equat ion 3

- 8 in Section 3.2.3 for the release rate. The Liquid Factor Boiling (L FB) for each toxic gas, needed to use Equation 3-8, is listed in Exhibit B-1 of Appendix B. See the example release rate estimation on the next

page.

After you have estimated the release rate, estimate the duration of the vapor release from the pool (the time it will take for the pool to evaporate completely) by dividing the total quantity spilled by the release rate. You need to know the duration of release to choose the appropriate reference table of distances to estimate the consequence distance, as discussed in Section 4. (You do not need to consider the duration of the release for chlorine or sulfur dioxide, liquefied by refrigeration alone. Only one reference table of distances is provided for worst-case releases of each of these su bstances, and these tables may be used regardless of the release duration. The principal reason for making no distinction between 10-minute and longer releases for the chemical-specific tables is that the differences between the two are small relative to the uncertainties that have been identified.)

April 15, 1999 3 - 3Chapter 3

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Example 3. Mitigated Release of Gases Liquefied by Refrigeration (Chlorine)

You have a refrigerated tank containing 50,000 p ounds of liquid chlorine at ambient pressure. A diked area

around the chlorine tank of 275 square feet is sufficient to hold all of the sp illed liquid chlorine. Once the

o liquid spills into the dike, it is then assumed to evaporate at its boiling point (-29 F). The evaporation rate at the boiling point is determined from Equation 3-8. For the calculation, wind speed is assumed to be 1.5 meters per second and the wind speed factor is 1.4, LFB for chlorine (from Exhibit B-1) is 0.19, and A is 275 square

feet. The release rate is:

QR = 1.4 × 0.19 × 275 = 73 p ounds per minute

The duration of the release does not need to be considered for chlorine.



### 3.2 Release Rates for Toxic Liquids

In Section 3.2

� 3.2.1 Method to estimate the quantity of toxic liquid that could be released from a broken pipe.

� 3.2.2 Method to estimate the release rate of a toxic liquid evaporating from a pool with no mitigation (no dikes or enclosures), including:

o -- Releases at ambient temperature (25 C), -- Releases at elevated temperature, and

-- Estimation of the duration of the release.

� 3.2.3 Method to estimate the release rate of a toxic liquid evaporating from a pool with passive mitigation, including:

-- Releases in diked areas, -- Releases into other types of containment, and -- Releases into buildings.

� 3.2.4 Estimation of release rates for mixtures containing toxic liquids.

� 3.2.5 Method to correct the estimated release rate for liquids released at

o o temperatures between 25 C and 50 C.

For the worst-case analysis, the release rate to air for toxic liquids is assumed to be the rate of evaporation from the pool formed by the released liquid. This section provides methods to estimate the evaporation rate. Assume the total quantity in a vessel or the maximum quantity from pipes is released into the pool. Passive mitigation measures (e.g., dikes) may be considered in determining the area of the pool and

April 15, 1999 3 - 4Chapter 3

Release Rates for Toxic Substances

the release rate. To estimate the consequence distance using this guidance, you must estimate how long it will take for the pool to evaporate (the duration of the release), as well as the release rate, as discussed below.

The rule (40 CFR 68.22(g)) requires you to assume that liq uids (other than gases liquefied by refrigeration) are released at the highest maximum daily temperature for the previous three years or at process

o o temperature, whichever is higher. This chapter provides methods to estimate the release rate at 25 C (77 F)

o or at the boiling point, and also provides a method to correct the release rate at 25 C for releases at

o o temperatures between 25 C and 50 C.

The calculation methods provided in this section apply to su bstances that are liq uids under ambient conditions or gases liquefied by refrigeration alone that are released to form pools deeper than one centimeter (see Section 3.1.3 above). You must treat gases liquefied under other conditions (under pressure or a combination of pressure and refrigeration) or gases liquefied by refrigeration alone that would form pools one centimeter or less in depth upon release as gas rather than liquid releases (see Sections 3.1.1 and 3.1.2 above).



### 3.2.1 Releases of Toxic Liquids from Pipes

To consider a liquid release from a broken pipe, estimate the maximum quantity that could be released assuming that the pipe is full of liquid. To estimate the quantity in the pipe, you need to know the length of the pipe (in feet) and cross-sectional area of the pipe (in square feet). Note also that liquid may be released from both directions at a pipe shear (both in the direction of operational flow and the reverse direction, depending on the location of the she ar). Therefore, the length w ould be the full length of pipe

carry ing the liquid on the facility grounds. Then, the volume of the liquid in the pipe (in cubic feet) is the length of the pipe times the cross-sectional area. The quantity in the pipe (in pounds) is the volume divided by the Density Factor (DF) times 0.033. (DF values are listed in Appe ndix B, Exhibit B-2. Density in pounds per cubic foot is equal to 1/(DF times 0. 033).) Assume the estimated quantity (in p ounds) is released into a pool and use the method and equations described below in Section 3.2.2 (unmitigated releases) or 3.2.3 (releases with passive mitigation) to determine the evaporation rate of the liquid from the pool.



### 3.2.2 Unmitigated Releases of Toxic Liquids

If no passive mitigation measures are in place, the liquid is assumed to form a pool one centimeter (0.39 inch or 0.033 foot) deep instantaneously. You may calculate the release rate to air from the pool (the evaporation rate) as discussed below for releases at ambient or elevated temperature.

Ambient Temperature

If the liquid is always at ambient temperature, find the Liquid Factor Ambient (LFA) and the Density

o Factor (DF) in Exhibit B-2 of Appendix B. The LFA and DF apply to liquids at 25 C; if your ambient

o o temperature is between 25 C and 50 C, you may use the method described here and then apply a Temperature Correction Factor (T CF), as discussed in Sect ion 3.2.5 below, to correct the calculated release

o rate. Calculate the release rate of the liquid at 25 C from the following equation:



### QR QS × 1.4 × LFA × DF (3-3) �

April 15, 1999 3 - 5Chapter 3

Release Rates for Toxic Substances

where: QR = Release rate (pounds per minute) QS = Quantity released (pounds)

1.4 = Wind speed factor = 1.5 0.78 , where 1.5 meters per second (3.4 miles per hour) is the wind speed for the worst case

LFA = Liquid Factor Ambient

DF = Density Factor

Example 4. Unmitigated Liquid Release at Ambient Temperature (Acrylonitrile)

You have a tank containing 20,000 p ounds of acrylonitrile at ambient temperature. The total quantity in the tank is spilled onto the ground in an undiked area, forming a pool. Assume the pool spreads out to a depth of one centimeter. The release rate from the pool (QR) is calculated from Equation 3-3. For the calculation, the wind speed is assumed to be 1.5 meters per second and the wind speed factor is 1.4. From Exhibit B-2, Appendix B, LFA for acrylonitrile is 0.018 and DF is 0.61. Then:

QR = 20,000 × 1.4 × 0.018 × 0.61 = 307 p ounds per minute

The duration of the release (from Equation 3-5) would be:

t = 20,000 p ounds/ 307 p ounds per minute = 65 minutes

Elevated Temperature

o If the liquid is at an elevated temperature (above 50 C or at or close to the boiling point), find the Liquid Factor Boiling (L FB) and the Density Factor (DF) in Exhibit B-2 of Appe ndix B (see Appendix D,

o Section D.2.2, for the derivation of these factors). For temperatures up to 50 C, you may use the method above for ambient temperature and apply the Temperature Correction Factors, as discussed in Section 3.2.5.

o If the temperature is above 50 C, or the liquid is at or close to its boiling point, or no Temperature Correction Factors are available for your liquid, calculate the release rate of the liquid from the following equation:



### QR QS × 1.4 × LFB × DF (3-4) �

where: QR = Release rate (pounds per minute) QS = Quantity released (pounds)

1.4 = Wind speed factor = 1.5 0.78 , where 1.5 meters per second (3.4 miles per hour) is the wind speed for the worst case

LFB = Liquid Factor Boiling

DF = Density Factor

April 15, 1999 3 - 6Chapter 3

Release Rates for Toxic Substances

Example 5. Unmitigated Release at Elevated Temperature (Acrylonitrile)

You have a tank containing 20,000 p ounds of acrylonitrile at an elevated temperature. The total quantity in the tank is spilled onto the ground in an undiked area, forming a pool. Assume the pool spreads out to a depth of one centimeter. The release rate from the pool is calculated from Equation 3-4. For the calculation, the wind speed factor for 1.5 meters per second is 1.4. From Exhibit B-2, Appendix B, LFB for acrylonitrile is 0.11 and

DF is 0.61. Then:

QR = 20,000 × 1.4 × 0.11 × 0.61 = 1,880 p ounds per minute

The duration of the release (from Equation 3-5) would be:

t = 20,000 p ounds/ 1880 p ounds per minute = 11 minutes

Duration of Release

After you have estimated a release rate as described above, determine the duration of the vapor release from the pool (the time it will take for the liquid pool to evaporate completely). If you calculate a

o corrected release rate for liquids above 25 C, use the corrected release rate, estimated as discussed in Section

3.2.5 below, to estimate the release duration. To estimate the time in minutes, divide the total quantity released (in pounds) by the release rate (in pounds per minute) as follows:



### QS t � (3-5) QR

where: t = Duration of the release (minutes) QR = Release rate (pounds per minute) (use release rate corrected for temperature, QR , if appropriate) C QS = Quantity released (pounds)

You will use the duration of the vapor release from the pool to decide which table is appropriate for estimating distance, as discussed in Chapter 4 below.



### 3.2.3 Releases of Toxic Liquids with Passive Mitigation

Diked Areas

If the toxic liquid will be released into an area where it will be contained by dikes, compare the diked area to the maximum area of the pool that could be formed; the smaller of the two areas should be used in determination of the evaporation rate. The maximum area of the pool (assuming a depth of one centimeter)

is:

April 15, 1999 3 - 7Chapter 3

Release Rates for Toxic Substances



### � A QS × DF (3-6)

where: A = Maximum area of pool (square feet) for depth of one centimeter QS = Quantity released (pounds)

DF = Density Factor (listed in Exhibit B-2, Appendix B)

Maximum Area Smaller than Diked Area . If the maximum area of the pool is smaller than the diked area, calculate the release rate as described for "no mitigation" above.

Diked Area Smaller than Maximum Area . If the diked area is smaller than the maximum pool area, go to Exhibit B-2 in Appendix B to find the Liquid Factor Ambient (LFA), if the liquid is at ambient temperature, or the Liquid Factor Boiling (L FB), if the liq uid is at an elevated temperature. For liquids at

o o temperatures between 25 C and 50 C, you may use the method described here and then apply a Temperature Correction Factor (T CF), as discussed in Sect ion 3.2.5 below, to correct the calculated release rate. For gases liquefied by refrigeration alone, use LFB from Exhibit B-1. Calculate the release rate from the diked area as follows for liquids at ambient temperature:



### QR 1.4 × LFA × A (3-7) �

or, for liquids at elevated temperature or for gases liquefied by refrigeration alone:



### QR 1.4 × LFB × A (3-8) �

where: QR = Release rate (pounds per minute)

1.4 = Wind speed factor = 1.5 0.78 , where 1.5 meters per second (3.4 miles per hour) is the wind speed for the worst case

LFA = Liquid Factor Ambient (listed in Exhibit B-2, Appendix B)

LFB = Liquid Factor Boiling (listed in Exhibit B-1 (for liquefied gases) or B-2 (for liquids), Appendix B)

A = Diked area (square feet)

Potential Overflow of Diked Area . In case of a large liquid spill, you also need to consider whether the liquid could overflow the diked area. Follow these steps:

Determine the volume of the diked area in cubic feet from surface area times depth or length times width times depth (in feet). �

Determine the volume of liquid spilled in cubic feet from QS × DF × 0. 033 (DF × 0.033 is equal to 1/density in pounds per cubic foot). �

Compare the volume of the diked area to the volume of liquid spilled. If the volume of liquid is greater than the volume of the diked area: �

-- Subtract the volume of the diked area from the total volume spilled to determine the volume that might overflow the diked area.

April 15, 1999 3 - 8Chapter 3

Release Rates for Toxic Substances

- - Estimate the maximum size of the pool formed by the overflowing liquid (in square feet) by dividing the overflow volume (in cubic feet) by 0. 033 (the depth of the pool in feet).

- - Add the su rface area of the diked area and the area of the pool formed by the overflow to estimate the total pool area (A).

- - Estimate the evaporation rate from Equation 3-7 or 3-8 above.

After you have estimated the release rate, estimate the duration of the vapor release from the pool by dividing the total quantity spilled by the release rate (Equation 3-5 above).

Example 6. Mitigated Liquid Release at Ambient Temperature (Bromine)

o You have a tank containing 20,000 p ounds of bromine at an ambient temperature of 25 C. Assume that the total quantity in the tank is spilled into a square diked area 10 feet by 10 feet (area 100 square feet). The dike walls are four feet high. The area (A) that would be covered to a depth of 0.033 feet (one centimeter) by the spilled liquid is given by Equation 3-6 as the quantity released (QS) times the Density Factor (DF). From Exhibit B-2, Appendix B, DF for bromine is 0.16. Then:

A = 20,000 × 0.16, or 3,200 square feet

The diked area is smaller than the maximum pool area. The volume of bromine spilled is 20, 000 × 0.16 × 0.033, or 106 cubic feet. The sp illed liquid would fill the diked area to a depth of a little more than one foot, well below the top of the wall. You use the diked area to determine the evaporation rate from Equation 3-7. For the calculation, wind speed is 1.5 meters per second, the wind speed factor is 1.4, LFA for bromine (from Exhibit B-2) is 0.073, and A is 100 square feet. The release rate is:

QR = 1.4 × 0.073 × 100 = 10 p ounds per minute

The maximum duration of the release would be:

t = 20,000 p ounds/10 pounds per minute = 2, 000 minutes

Other Containment

If the toxic liquid will be contained by other means (e.g., enclosed catch basins or trenches), consider the total quantity that could be spilled and estimate the surface area of the released liquid that potentially would be exposed to the air. Look at the dimensions of trenches or other areas where spilled liquids would be exposed to the air to determine the surface area of pools that could be formed. Use the instructions above to

estimate a release rate from the total surface area.

April 15, 1999 3 - 9Chapter 3

Release Rates for Toxic Substances

Releases into Buildings

If the toxic liquid is released inside a building, compare the area of the pool that would be formed (depending upon floor space or passive mitigation) to the maximum area of the pool that could be formed (if the liquid is not contained); the smaller of the two areas should be used in determining the evaporation rate. The maximum area of the pool is determined as described above for releases into diked areas, using Equation 3-6. If the toxic liquid would spread to cover the building floor, you determine the area of the building floor

as:



### A L × W (3-9) �

where: A = Area (square feet)

L = Length (feet)

W = Width (feet)

If there are obstacles such as dikes inside the building, determine the size of the pool that would be formed based on the area defined by the dikes or other o bstacles.

The evaporation rate is then determined for a worst-case scenario (i.e., wind speed is 1.5 meters per second (3.4 miles per hou r)), us ing Equation 3-3 or 3-4, if the liquid spreads to its maximum area, or Equation 3-7 or 3-8, if the pool area is smaller than the maximum. The maximum rate of evaporated liquid exiting the building is taken to be 10 percent of the calculated worst-case scenario evaporation rate (see Appendix D, Section D.2.4 for the derivation of this factor), as follows:



### � QR B 

### 0.1 × QR (3-10)

where: QR B = Release rate from building QR = Release rate from pool, estimated as discussed above

0.1 = Mitigation factor, discussed in Appendix D, Section D.2.4

Note that the mitigation factor (i.e., 0.1) presented in this method assumes that the release occurs in a fully enclosed, non-airtight space that is directly adjacent to the outside air. It may not apply to a release in an interior room that is enclosed within a building, or to a space that has doors or windows that could be open during a release. In such cases, you may want to consider performing site-specific modeling to determine the appropriate amount of passive mitigation.

April 15, 1999 3 - 10Chapter 3

Release Rates for Toxic Substances

Example 7. Liquid Release Inside Building (Bromine)

Suppose that your tank of bromine from Example 6 is contained inside a storage shed 10 feet by 10 feet (area 100 square feet). There are no dikes inside the shed. From Example 6, you see that the area covered by the bromine in an unenclosed space would be 3, 200 square feet. The building area is smaller than the maximum pool area; therefore, the building floor area should be used to determine the evaporation rate from Equation 3

- 7. For the calculation, first determine the worst-case scenario evaporation rate:

QR = 1.4 × 0.073 × 100 = 10 p ounds per minute

The release rate to the outside air of the evaporated liquid leaving the building would then be:

QR B = 0.1 × 10 pounds per minute = 1 pound per minute



### 3.2.4 Mixtures Containing Toxic Liquids

Mixtures containing regulated toxic su bstances do not have to be considered if the concentrat ion of the regulated su bstance in the mixture is below one percent by we ight or if you can demonstrate that the partial vapor pressure of the regulated su bstances in the mixture is below 10 m illimeters of mercury (mm Hg). Regulated su bstances present as by-pr oducts or impurities would need to be considered if they are present in concentrations of one percent or greater in quantities above their thresholds, and their partial vapor pressures are 10 mm Hg or higher. In case of a spill of a liquid mixture containing a regulated toxic substance with partial vapor pressure of 10 mm Hg or higher (with the exception of common water solutions, discussed in the next section), you have several options for estimating a release rate:

Carry out the analysis as described above in Sect ions 3.2.2 or 3.2.3 using the quantity of the regulated su bstance in the mixture and the liq uid factor (LFA or L FB) and density factor for the regulated su bstance in pure form. This is a simple approach that likely will give

conservative results. �

If you know the partial pressure of the regulated su bstance in the mixture, you may estimate a more realistic evaporation rate. An equation for the evaporation rate is given at the end of Section B.2 in Appendix B. �

-- In this case, estimate a pool size for the entire quantity of the mixture, for an unmitigated release. If you know the density of the mixture, you may use it in estimating the pool size; otherwise, you may assume the density is the same as the pure regulated su bstance (in most cases, this assumpt ion is unlikely to have a large effect on the results).

You may estimate the partial pressure of the regulated su bstance in the mixture by the method described in Section B.2 in Appendix B and use the equation presented there to estimate an evaporation rate. This equation is appropriate to mixtures and solutions in �

April 15, 1999 3 - 11Chapter 3

Release Rates for Toxic Substances

which the components do not interact with each other. It is probably inappropriate for most water solutions. It is likely to overestimate the partial vapor pressure of regulated

substances in water s olutions in which hydrogen bonding may occur (e.g., solutions of acids or alcohols). As discussed above, use the pool size for the entire quantity of the mixture for an unmitigated release.

Example 8. Mixture Containing Toxic Liquid (Acrylonitrile)

You have a tank containing 50,000 p ounds of a mixture of acrylonitrile (a regulated substance) and N,N

dimethylformamide (not regulated). The weight of each of the components of the mixture is known (acrylonitrile = 20,000 p ounds; N,N-dimethylformamide = 30, 000 p ounds.) The molecular weight of acrylonitrile, from Exhibit B-2, is 53.06, and the molecular weight of N,N-dimethylformamide is 73.09. Using Equation B-3, Appendix B, calculate the mole fraction of acrylonitrile in the solution as follows:

X

r

= (20,000/53.06) (20,000/53.06) + (30,000/73.09)

X

r

= 377

377 + 410

X

r

= 0.48

Estimate the partial vapor pressure of acrylonitrile using Equation B-4 as follows (using the vapor pressure of acrylonitrile in pure form at 25 � C, 108 mm Hg, from Exhibit B-2, Appendix B):

VP

m = 0.48 × 108 = 51.8 mm Hg

Before calculating evaporation rate for acrylonitrile in the mixture, you must determine the surface area of the pool formed by the entire quantity of the mixture, using Equation 3-6. The quantity released is 50, 000 p ounds and the Density Factor for acrylonitrile is 0.61 in Exhibit B-2; therefore:

A = 50,000 × 0.61 = 30,500 square feet

Now calculate the evaporation rate for acrylonitrile in the mixture from Equation B-5 using the VP

m and A

calculated above:

QR = 0.0035 × 1.0 × (53.06) � × 30,500 × 51.8

298

QR = 262 p ounds per minute



### 3.2.5 Release Rate Correction for Toxic Liquids Released at Temperatures

o o 

### Between 25 C and 50 C

o o o o If your liquid is at a temperature between 25 C (77 F) and 50 C ( 122 F), you must use the higher temperature for the offsite consequence analysis. You may correct the release rate calculated for a pool at 25

April 15, 1999 3 - 12Chapter 3

Release Rates for Toxic Substances

o C to estimate from a pool at the higher temperature using Temperature Correction Factors (T CF) pr ovided in Appendix B, Exhibit B-4. Calculate a corrected release rate as follows:

o o Calculate the release rate (QR) of the liquid at 25 C (77 F) as described in Section 3.2.2 (for unmitigated releases) or 3.2.3 (for releases with passive mitigation). �

From Exhibit B-4 in Appendix B: �

-- Find your liquid in the left-hand column of the table.

-- Find the temperature closest to your temperature at the top of the table. If your temperature is at the midpoint between two temperatures, go to the higher temperature; otherwise go to the closest temperature (higher or lower than your temperature).

-- Find the TCF for your liquid in the column for the appropriate temperature.

Estimate a corrected release rate (QR ) by multiplying the estimated release rate by the TCF; � C i.e.,



### � QR C 

### QR × TCF (3-11)

where: QR C = Corrected release rate

o QR = Release rate calculated for 25 C

TCF = Temperature Correction Factor (from Exhibit B-4, Appe ndix B)

The derivation of the Temperature Correction Factors is discussed in Appendix D, Section D.2.2. If you have vapor pressure-temperature data for a liquid not covered in Exhibit B-4, you may correct the evaporation rate using the method presented in Section D.2.2.

April 15, 1999 3 - 13Chapter 3

Release Rates for Toxic Substances

o o Example 9. Liquid Release at Ambient Temperature Between 25 C and 50 C (Bromine)

o Assume the tank containing 20,000 p ounds of bromine, from Example 6, is at an ambient temperature of 35 C

o As in Example 6, the total quantity in the tank is spilled into a diked enclosure that completely contains (95 F).

o the spill. The surface area is 100 square feet. In Example 6, the release rate (QR) at 25 C was calculated from

o Equation 3-7 to be 10 pounds per minute. To adjust the release rate for the temperature of 35 C, you find the

o Temperature Correction Factor (TCF) for bromine at 35 C from Exhibit B-4 in Appendix B. The TCF at this

o temperature is 1.5; the corrected release rate (QR ) at 35 C, from Equation 3-11, is C

QR C = 10 × 1.5 = 15 pounds per minute

The duration of the release (from Equation 3-5) would be:

t = 20,000 p ounds/15 pounds per minute = 1, 300 minutes



### 3.3 Release Rates for Common Water Solutions of Toxic Substances and for
Oleum

In Section 3.3

� Methods to estimate the release rates for several common water solutions and for oleum, including:

-- Evaporation from pools with no mitigation (see 3.2.2), -- Evaporation from pools with dikes (see 3.2.3), -- Releases at elevated temperatures of solutions of gases, and -- Releases at elevated temperatures of solutions of liquids.

This section presents a simple method of estimating the release rate from spills of water solutions of several substances. Oleum (a s olution of sulfur trioxide in sulfuric acid) also is discussed in this section.

The vapor pressure and evaporation rate of a su bstance in s olution depends on its concentration in the solution. If a concentrated water solution containing a volatile toxic su bstance is sp illed, the toxic

substance initially will evaporate more quickly than water from the spilled solution, and the vapor pressure and evaporation rate will decrease as the concentration of the toxic su bstance in the s olution decreases. At much lower concentrations, water may evaporate more quickly than the toxic su bstance. There is one concentration at which the composition of the solution does not change as evaporation occurs. For most situations of interest, the concentration ex ceeds this concentrat ion, and the toxic su bstance evaporates more quickly than water.

For estimating release rates from solutions, this guidance li sts liq uid factors (ambient) for several common water solutions at several concentrations that take into account the decrease in evaporation rate with decreasing concentration. Exhibit B-3 in Appendix B provides LFA and DF values for several concentrations

April 15, 1999 3 - 14Chapter 3

Release Rates for Toxic Substances

of ammonia, formaldehyde, hydrochloric acid, hydrofluoric acid, and nitric acid in water solution. Factors for oleum are also included in the exhibit. Chlorine dioxide also may be found in water solutions; however, solutions of chlorine dioxide commonly are below one percent concentration. Solutions below one percent concentration do not have to be considered. Chlorine dioxide, therefore, is not included in Exhibit B-3. These factors may be used to estimate an average release rate for the listed substances from a p ool formed by a spill of solution. Liquid factors are provided for two different wind speeds, because the wind speed affects the rate of evaporation.

For the worst case, use the factor for a wind speed of 1.5 meters per second (3.4 miles per hour). You need to consider only the first 10 minutes of the release for solutions under ambient conditions in estimating the consequence distance, because the toxic component in a solution evaporates fastest during the first few minutes of a spill, when its concentration is highest. Modeling indicates that analysis considering the first 10 minutes of the release gives a good approximation of the overall consequences of the release. Although the toxic su bstance w ill continue to evaporate from the pool after 10 minutes, the rate of evaporation is so much lower that it can safely be ignored in estimating the consequence distance. (See Appendix D, Section D.2.3, for more information.) Estimate release rates as follows:

Ambient Temperature

Unmitigated . If no passive mitigation measures are in place, and the solution is at ambient temperature, find the LFA at 1.5 meters per second (3.4 miles per hour) and DF for the solution in Appendix B, Exhibit B-3. Follow the instructions for liquids presented in

Section 3.2.2 above to estimate the release rate of the listed su bstance in s olution. Use the total quantity of the solution as the quantity released (QS) in c arry ing out the calculation of

release rate. �

Mitigated . If passive mitigation is in place, and the solution is at ambient temperature, find the LFA at 1.5 meters per second (3.4 miles per hour) in Appendix B, Exhibit B-3, and follow the instructions for liquids in Section 3.2.3 above. Use the total quantity of the solution to estimate the maximum pool area for comparison with the diked area. �

April 15, 1999 3 - 15Chapter 3

Release Rates for Toxic Substances

Example 10. Evaporation Rate for Water Solution at Ambient Temperature (Hydrochloric Acid)

You have a tank containing 50,000 p ounds of 37 percent hydrochloric acid solution, at ambient temperature. For the worst-case analysis, you assume the entire contents of the tank is released, forming a pool. The release occurs in a diked area of 9,000 square feet.

From Exhibit B-3, Appendix B, the Density Factor (DF) for 37 percent hydrochloric acid is 0.42. From Equation 3-6, the maximum area of the pool would be 50,000 times 0.42, or 21,000 square feet. The diked area is smaller; therefore, the diked area should be used in the evaporation rate (release rate) calculation, using Equation 3-7.

For the calculation using Equation 3-7, you need the pool area (9,000 square feet) and the Liquid Factor Ambient (LFA) for 37 percent hydrochloric acid; you assume a wind speed of 1.5 meters per second, so the wind speed factor is 1.4. From Exhibit B-3, Appendix B, the LFA is 0.0085. From Equation 3-7, the release rate (QR) of hydrogen chloride from the pool is:

QR = 1.4 × 9,000 × 0.0085 = 107 p ounds per minute

You do not need to consider the duration of the release, because only the first ten minutes are considered.

Elevated Temperature

Known Vapor Pressure . If the solution is at an elevated temperature, the vapor pressure of the regulated su bstance and its release rate from the s olution will be much higher. This guidance does not include temperature correction factors for evaporation rates of regulated

substances from s olutions. If you know the partial vapor pressure of the toxic su bstance in solution at the relevant temperature, you can c arry out the calculat ion of the release rate using the equations in Appendix D, Sections D.2.1 and D.2.2. As for releases of solutions at ambient temperature, you only need to consider the first 10 minutes of the release, because the evaporation rate of the toxic su bstance from the s olution will decrease rapidly as its

concentration decreases. �

Unknown Vapor Pressure . If you do not know the vapor pressure of the su bstance in solution, as a conservative approach for the worst-case analysis, use the appropriate instructions, as follows: �

-- Solutions containing substances that are gases under ambient conditions . The list of regulated su bstances inc ludes several su bstances that, in their pure form, are gases under ambient conditions, but that may commonly be found in water

solutions. These su bstances inc lude ammonia, formaldehyde, hydrogen chloride, and hydrogen fluoride. For a release of a solution of ammonia, formaldehyde, hydrochloric acid, or hydrofluoric acid above ambient temperature, if you do not have vapor pressure data for the temperature of interest or prefer a simpler method, assume the quantity of the pure substance in the s olution is released as a gas over 10

April 15, 1999 3 - 16Chapter 3

Release Rates for Toxic Substances

minutes, as discussed in Section 3.1 above. You may determine the amount of pure

substance in the s olution from the concentration (e.g., a solution of 37 percent hydrochloric acid by weight would contain a quantity of hydrogen chloride equal to

0.37 times the total weight of the solution).

Example 11. Evaporation Rate for Gas in Water Solution at Elevated Temperature (Hydrochloric Acid)

You have 50,000 p ounds of 37 percent hydrochloric acid solution in a high-temperature process. For the worst-case analysis, you assume the entire contents of the process vessel is released. In this case, because the solution is at an elevated temperature, you consider the release of gaseous hydrogen chloride from the hot

solution.

The solution would contain 50,000 × 0.37 p ounds of hydrogen chloride, or 18, 500 p ounds. You assume the entire 18,500 p ounds is released over 10 minutes. From Equation 3-1, the release rate is 18, 500 divided by 10, or 1,850 p ounds per minute.

-- Liquids in solution . If you have vapor pressure data for the liquid in solution (including nitric acid in water solution and sulfur trioxide in oleum) at the temperature of interest, you may use that data to estimate the release rate, as discussed above. You only need to consider the first 10 minutes of the evaporation.

For a release of nitric acid solution at a temperature above ambient, if you do not have vapor pressure data or prefer to use this simpler method, determine the quantity of pure nitric acid in the solution from the concentration. Assume the quantity of pure nitric acid is released at an elevated temperature and estimate a release rate as discussed in Section 3.2 above, using the LFB. For temperatures

o o between 25 C and 50 C, you may use the LFA and the temperature correction factors for the pure substance, as described in Sect ion 3.2.5. You do not need to estimate the duration of the release, because you only consider the first 10 minutes.

Similarly, for a release of oleum at an elevated temperature, determine the quantity

of free sulfur trioxide in the oleum from the concentration and assume the sulfur trioxide is released at an elevated temperature. Use the LFB or the LFA and temperature correction factors for sulfur trioxide to estimate a release rate as discussed in Section 3.2. You only need to consider the first 10 minutes of the release in your analysis.

For a spill of liquid in solution into a diked area, you would need to consider the total quantity of solution in determining whether the liquid could overflow the diked area (see the steps in Section 3.2.3). If you find that the liquid could overflow the dikes, you would need to consider both the quantity of pure su bstance rema ining inside the diked area and the quantity of pure su bstance sp illed outside the diked area in carry ing out the release rate analysis as discussed in Section 3.2.3.

April 15, 1999 3 - 17Chapter 3

Release Rates for Toxic Substances

Example 12. Evaporation Rate for Liquid in Water Solution at Elevated Temperature (Nitric Acid)

You have 18,000 p ounds of 90 percent nitric acid solution in a high temperature process. The solution would contain 18,000 x 0.90 p ounds of nitric acid, or 16, 200 p ounds. You assume 16, 200 p ounds of pure nitric acid is released at an elevated temperature.

For the calculation using Equation 3-4, you need the quantity released (16, 200); the Liquid Factor Bo iling (LFB) for nitric acid (0.12 from Exhibit B-2); the Density Factor (DF) for nitric acid (0.32 from Exhibit B-2); and you assume a wind speed of 1.5 meter per second, so the wind speed factor is 1.4. From Equation 3-4, the release rate (QR) of hot nitric acid is:

QR = 16,200 × 1.4 × 0.12 × 0.32 = 870 p ounds per minute

You do not need to estimate the duration of release, because you only consider the first 10 minutes.

April 15, 1999 3 - 18

## 4 ESTIMATION OF WORST-CASE DISTANCE TO TOXIC

ENDPOINT

In Chapter 4

� Reference tables of distances for worst-case releases, including:

-- Generic reference tables (Exhibit 2), and -- Chemical-specific reference tables (Exhibit 3).

� Considerations include:

-- Gas density (neutrally buoyant or dense), -- Duration of release (10 minutes or 60 minutes), -- Topography (rural or urban).

This guidance provides reference tables giving worst-case distances for neutrally buoyant gases and vapors and for dense gases and vapors for both rural (open) and urban (obstructed) areas. This chapter describes these reference tables and gives instructions to help you choose the appropriate table to estimate consequence distances for the worst-case analysis.

Neutrally buoyant gases and vapors have approximately the same density as air, and dense gases and vapors are heavier than air. Neutrally buoyant and dense gases are dispersed in different ways when they are released; therefore, modeling was c arried out to develop separate reference tables. These generic reference tables can be used to estimate distances using the specified toxic endpoint for each su bstance and the estimated release rate to air. In addition to the generic tables, chemical-specific reference tables are provided for ammonia, chlorine, and sulfur dioxide. These chemical-specific tables were developed based on modeling

carried out for industry-specific guidance documents. All the tables were developed assuming a wind speedof 1.5 meters per second (3.4 miles per hour) and F stability. To use the reference tables, you need the worstcase release rates estimated as described in the previous sections. For liquid pool evaporation, you also need the duration of the release. In addition, to use the generic tables, you will need to determine the appropriate toxic endpoint and whether the gas or vapor is neutrally buoyant or dense, using the exhibits in Appendix B. You may interpolate between entries in the reference tables.

Generic reference tables are provided for both 10-minute releases and 60-minute releases. You should use the tables for 10-minute releases if the duration of your release is 10 minutes or le ss; use the tables for 60-minute releases if the duration of your release is more than 10 minutes. For the worst-case analysis, all releases of toxic gases are assumed to last for 10 minutes. You need to consider the estimated duration of the release (from Equat ion 3-5) for evaporation of pools of toxic liquids. For evaporation of water solutions of toxic liquids or of oleum, you should always use the tables for 10-minute releases.

The generic reference tables of distances (Reference Tables 1-8), which should be used for

substances other than amm onia, chlorine, and sulfur dioxide, are found at the end of Chapter 5. The generic tables and the conditions for which each table are applicable are described in Exhibit 2. Chemical-specific reference tables of distances (Reference Tables 9-12) follow the generic reference tables at the end of Chapter

5. Each of these chemical-specific tables includes distances for both rural and urban topography. These

tables are described in Exhibit 3.

April 15, 1999Chapter 4 Estimation of Worst-Case Distance to Toxic Endpoint

Remember that these reference tables pr ovide only rough estimates, not accurate predictions, of the distances that might be reached under worst-case conditions. In particular, although the distances in the tables are as great as 25 miles, you should bear in mind that the larger distances (more than six to ten miles) are very uncertain.

To use the reference tables of distances, follow these steps:

For Regulated Toxic Substa nces Other than Ammonia, Ch lorine, and Sulfur Dioxide

Find the toxic endpoint for the su bstance in Appe ndix B (Exhibit B-1 for toxic gases or Exhibit B-2 for toxic liquids). �

Determine whether the table for neutrally buoyant or dense gases and vapors is appropriate from Appendix B (Exhibit B-1 for toxic gases or Exhibit B-2 for toxic liquids). A toxic gas that is lighter than air may behave as a dense gas upon release if it is liquefied under pressure, because the released gas may be mixed with liquid droplets, or if it is cold. Consider the state of the released gas when you decide which table is appropriate. �

Determine whether the table for rural or urban conditions is appropriate. �

-- Use the rural table if your site is in an open area with few obstruct ions.

-- Use the urban table if your site is in an urban or obstructed area. The urban tables are appropriate if there are many obstruct ions in the area, even if it is in a remote location, not in a city.

Determine whether the 10-minute table or the 60-minute table is appropriate. �

-- Always use the 10-minute table for worst-case releases of toxic gases.

-- Always use the 10-minute table for worst-case releases of common water solutions and oleum from evaporating pools, for both ambient and elevated temperatures.

-- If you estimated the release duration for an evaporating toxic liquid pool to be 10 minutes or less, use the 10-minute table.

-- If you estimated the release duration for an evaporating toxic liquid pool to be more than 10 minutes, use the 60-minute table.

April 15, 1999 4 - 2Chapter 4 Estimation of Worst-Case Distance to Toxic Endpoint

Exhibit 2

Generic Reference Tables of Distances for Worst-case Scenarios

Applicable Conditions Reference Table

Number Gas or Vapor Density Topography Release Duration (minutes)

Neutrally buoyant Rural 10 1

60 2

Urban 10 3

60 4

Dense Rural 10 5

60 6

Urban 10 7

60 8

Exhibit 3 Chemical-Specific Reference Tables of Distances for Worst-case Scenarios

Substance Applicable Conditions

Table Reference

Number Gas or Vapor Density Topography Release Duration (minutes)

Anhydrous ammonia liquefied under pressure Dense Rural, Urban 10 9

Non-liquefied ammonia, ammonia liquefied by refrigeration, or aqueous

ammonia Neutrally buoyant Rural, Urban 10 10

Chlorine Dense Rural, Urban 10 11

Sulfur dioxide (anhydrous) Dense Rural, Urban 10 12

April 15, 1999 4 - 3Chapter 4 Estimation of Worst-Case Distance to Toxic Endpoint

Neutrally Buoyant Gases or Vapors

If Exhibit B-1 or B-2 indicates the gas or vapor should be considered neutrally buoyant, and other factors would not cause the gas or vapor to behave as a dense gas, divide the estimated release rate (pounds per minute) by the toxic endpoint (milligrams per liter). �

Find the range of release rate/toxic endpoint values that includes your calculated release rate/toxic endpoint in the first column of the appropriate table (Reference Table 1, 2, 3, or 4), then find the corresponding distance to the right (see Example 13 below). �

Dense Gases or Vapors

If Exhibit B-1 or B-2 or consideration of other relevant factors indicates the su bstance should be considered a dense gas or vapor (heavier than air), find the distance in the appropriate table (Reference Table 5, 6, 7, or 8) as follows; �

-- Find the toxic endpoint closest to that of the su bstance by rea ding across the top of the table. If the endpoint of the su bstance is halfway between two values on the table, choose the value on the table that is smaller (to the left). Otherwise, choose the closest value to the right or the left.

-- Find the release rate closest to the release rate estimated for the su bstance at the left of the table. If the calculated release rate is halfway between two values on the table, choose the release rate that is larger (farther down on the table). Otherwise, choose the closest value (up or down on the table).

-- Read across from the release rate and down from the endpoint to find the distance corresponding to the toxic endpoint and release rate for your su bstance.

For Ammonia, Ch lorine, or Sulfur Dioxide

Find the appropriate chemical-specific table for your su bstance (see the descript ions of Reference Tables 9-12 in Exhibit 3). �

-- If you have ammonia liquefied by refrigeration alone, you may use Reference Table 10, even if the duration of the release is greater than 10 minutes.

-- If you have chlorine or sulfur dioxide liquefied by refrigeration alone, you may use the chemical-specific reference tables, even if the duration of the release is greater

than 10 minutes.

Determine whether rural or urban topography is applicable to your site. �

-- Use the rural column in the reference table if your site is in an open area with few

obstruct ions.

April 15, 1999 4 - 4Chapter 4 Estimation of Worst-Case Distance to Toxic Endpoint

-- Use the urban column if your site is in an urban or o bstructed area. The urban column is appropriate if there are many o bstruct ions in the area, even if it is in a remote location, not in a city.

Estimate the consequence distance as follows: �

-- In the left-hand column of the table, find the release rate closest to your calculated

release rate.

-- Read the corresponding distance from the appropriate column (urban or rural) to the right.

The development of Reference Tables 1-8 is discussed in Appendix D, Sections D.4.1 and D.4.2. The development of Reference Tables 9-12 is discussed in industry-specific risk manag ement program guidance documents and a backup information document that are cited in Section D.4.3. If you think the results of the method presented here overstate the potential consequences of a worst-case release at your site, you may choose to use other methods or models that take additional site-specific factors into account.

Examples 14 and 15 below include the results of modeling using two other models, the Areal

Locations of H azar dous Atmospheres (ALOHA) and the World Bank H azards Analysis ( WHAZAN) systems. These additional results are provided for comparison with the results of the methods presented in this guidance. The same modeling parameters were used as in the modeling c arried out for development of the reference tables of distances. Appendix D, Section D.4.5, provides information on the modeling c arried

out with ALOHA and WHAZAN.

Example 13. Gas Release (Diborane)

In Example 1, you estimated a release rate for diborane gas of 250 p ounds per minute. From Exhibit B-1, the toxic endpoint for diborane is 0.0011 mg/L, and the appropriate reference table for diborane is a neutrally buoyant gas table. Your facility and the surrounding area have many buildings, pieces of equipment, and other obstructions; therefore, you assume urban conditions. The appropriate reference table is Reference Table 3, for a 10-minute release of a neutrally buoyant gas in an urban area.

The release rate divided by toxic endpoint for this example is 250/0.0011 = 230,000.

From Reference Table 3, release rate divided by toxic endpoint falls between 221,000 and 264,000, corresponding to about 8.1 miles.

April 15, 1999 4 - 5Chapter 4 Estimation of Worst-Case Distance to Toxic Endpoint

Example 14. Gas Release (Ethylene Oxide)

You have a tank containing 10,000 p ounds of ethylene oxide, which is a gas under ambient conditions. Assuming the total quantity in the tank is released over a 10-minute period, the release rate (QR) from Equation

3-1 is:

QR = 10,000 p ounds/10 minutes = 1, 000 p ounds per minute

From Exhibit B-1, the toxic endpoint for ethylene oxide is 0.09 mg/L, and the appropriate reference table is the dense gas table. Your facility is in an open, rural area with few obstructions; therefore, you use the table for

rural areas.

Using Reference Table 5 for 10-minute releases of dense gases in rural areas, the toxic endpoint of 0.09 mg/L is closer to 0.1 than 0.075 mg/L. For a release rate of 1,000 p ounds per minute, the distance to 0.1 mg/L is 3.6

miles.

Additional Modeling for Comparison

The ALOHA model gave a distance of 2.2 miles to the endpoint, using the same assumptions.

The WHAZAN model gave a distance of 2.7 miles to the endpoint, using the same assumptions and the dense cloud dispersion model.

Example 15. Liquid Evaporation from Pool (Acrylonitrile)

You estimated an evaporation rate of 307 p ounds per minute for acrylonitrile from a pool formed by the release of 20,000 p ounds into an undiked area (Example 4). You estimated the time for evaporation of the pool as 65 minutes. From Exhibit B-2, the toxic endpoint for acrylonitrile is 0.076 mg/L, and the appropriate reference table for a worst-case release of acrylonitrile is the dense gas table. Your facility is in an urban area. You use Reference Table 8 for 60-minute releases of dense gases in urban areas.

From Reference Table 8, the toxic endpoint closest to 0.076 mg/L is 0.075 mg/L, and the closest release rate to 307 p ounds per minute is 250 p ounds per minute. Using these values, the table gives a worst-case consequence distance of 2.9 miles.

Additional Modeling for Comparison

The ALOHA model gave a distance of 1.3 miles to the endpoint for a release rate of 307 p ounds per minute, using the same assumptions.

The WHAZAN model gave a distance of 1.0 mile to the endpoint for a release rate of 307 p ounds per minute, using the same assumptions and the dense cloud dispersion model.

April 15, 1999 4 - 6

## 5 ESTIMATION OF DISTANCE TO OVERPRESSURE ENDPOINT

FOR FLAMMABLE SUBSTANCES

In Chapter 5

� Methods to estimate the worst-case consequence distances for releases of

flammable substances.

-- 5.1 Vapor cloud explosions of flammable substances that are not mixed with other substances, and -- 5.2 Vapor cloud explosions of flammable substances in mixtures.

For the worst-case scenario involving a release of flammable gases and volatile flammable liquids, you must assume that the total quantity of the flammable substance forms a vapor c loud within the upper and lower flammability limits and the cloud detonates. As a conservative worst-case assumption, if you use the method presented here, you must assume that 10 percent of the flammable vapor in the cloud participates in the explosion. You need to estimate the consequence distance to an overpressure level of 1 pound per square inch (psi) from the explosion of the vapor cloud. An overpressure of 1 psi may cause partial demolition of houses, which can result in serious injuries to people, and shattering of glass windows, which may cause skin laceration from flying glass.

This chapter presents a simple method for estimating the distance to the endpoint for a vapor cloud explosion of a regulated su bstance. The met hod presented here for analysis of vapor cloud explosions is based on a TNT-equivalent model. Other methods are available for analysis of vapor cloud explosions, including methods that consider site-specific conditions. You may use other methods for your worst-case analysis if you so choose, provided you assume the total quantity of flammable su bstance is in the c loud and use an endpoint of 1 psi. If you use a TNT-equivalent model, you must assume a yield factor of 10 percent. Appendix A includes references to documents and journal articles on vapor cloud explosions that may provide useful information on methods of analysis.



### 5.1 Flammable Substances Not in Mixtures

For the worst-case analysis of a regulated flammable su bstance that is not in a mixture with other substances, you may estimate the consequence distance for a given quantity of a regulated flammable

substance us ing Reference Table 13. This table provides distances to 1 psi overpressure for vapor cloud explosions of quantities from 500 to 2,000,000 p ounds. These distances were estimated by a TNTequivalent model, Equation C-1 in Appendix C, Section C.1, using the worst-case assumptions described above and data provided in Exhibit C-1, Appendix C. If you prefer, you may calculate your worst-case consequence distance for flammable substances from the heat of combust ion of the flammable su bstance and Equation C-1 or C-2.

April 15, 1999Chapter 5 Estimation of Distance to Overpressure Endpoint for Flammable Substances

Example 16. Vapor Cloud Explosion (Propane)

You have a tank containing 50,000 p ounds of propane. From Reference Table 13, the distance to 1 psi overpressure is 0.3 miles for 50,000 p ounds of propane.

Alternatively, you can calculate the distance to 1 psi using Equation C-2 from Appendix C:

D = 0.0081 × [ 0.1 × 50,000 × (46,333/4,680) ] 1/3

D = 0.3 miles



### 5.2 Flammable Mixtures

If you have more than 10,000 p ounds of a mixture of flammable su bstances that meets the criteria

o o o for listing under CAA section 112(r) (flash p oint below 22.8 C (73 F), boiling point below 37.8 C (100

o F), National Fire Protection Association (NFPA) flammability h azard rat ing of 4), you may need to c arry out a worst-case consequence analysis for the mixture. (If the mixture itself does not meet these criteria, it is not covered, and no analysis is required, even if the mixture contains one or more regulated su bstances.) You

should c arry out the analysis us ing the total quantity of all regulated flammable su bstance or substances in the mixture. Non-flammable components should not be included. However, if additional (non-regulated) flammable substances are present in the mixture, you s hould include them in the quantity used in the analysis.

For simplicity, you may carry out the worst-case analysis based on the predominant re gulated flammable component of the mixture or a major component of the mixture with the highest heat of combustion if the whole vapor cloud consi sts of flammable substances (see Exhibit C-1, Appe ndix C for data on heat of combustion). Estimate the consequence distance from Reference Table 13 for the major component with the highest heat of combustion, assuming that the quantity in the cloud is the total quantity of the mixture. If you have a mixture in which the heats of combustion of the components do not differ significantly (e.g., a mixture of hydrocarbons), this method is likely to give reasonable results.

Alternatively, you may estimate the heat of combustion of the mixture from the heats of combustion of the components of the mixture using the method described in Appendix C, Section C.2, and then use Equation C-1 or C-2 in Appendix C to determine the vapor cloud explosion distance. This method may be appropriate if you have a mixture that includes components with significantly different heats of combustion (e.g., a mixture of hydrogen and hydrocarbons) that make up a significant portion of the mixture.

Examples 17 and 18 illustrate the two methods of analysis. In Example 17, the heat of combustion of the mixture is estimated, and the distance to the endpoint is calculated from Equation C-2. In Example 18, the component of the mixture with the highest heat of combustion is assumed to represent the entire mixture, and the distance to the endpoint is read from Reference Table 13. For the mixture of two hydrocarbons used in the example, the methods give very similar results.

April 15, 1999 5 - 2Chapter 5 Estimation of Distance to Overpressure Endpoint for Flammable Substances

Example 17. Estimating Heat of Combustion of Mixture for Vapor Cloud Explosion Analysis

You have a mixture of 8,000 p ounds of ethylene (the reactant) and 2, 000 p ounds of isobutane (a catalyst carrier). To carry out the worst-case analysis, estimate the heat of combustion of the mixture from the heats of combustion of the components of the mixture. (Ethylene heat of combustion = 47,145 kilojoules per kilogram; isobutane heat of combustion = 45,576). Using Equation C-3, Appendix C:

HC

m = [ (8,000/2.2) × 47,145 ] + [ (2,000/2.2) × 45,576 ] (10,000/2.2) (10,000/2.2)

HC

m = (37,716) + (9,115)

HC

m = 46,831 kilojoules per kilogram

Now use the calculated heat of combustion for the mixture in Equation C-2 to calculate the distance to 1 psi overpressure for vapor cloud explosion.

D = 0.0081 × [ 0.1 × 10,000 × (46,831/4,680) ] �

D = 0.2 miles

Example 18. Vapor Cloud Explosion of Flammable Mixture (Ethylene and Isobutane)

You have 10,000 p ounds of a mixture of ethylene (the reactant) and isobutane (a catalyst carrier). To carry out the worst-case analysis, assume the quantity in the cloud is the total quantity of the mixture. Use data for ethylene because it is the component with the highest heat of combustion. (Ethylene heat of combustion = 47,145 kilojoules per kilogram; isobutane heat of combustion = 45,576, from Exhibit C-1, Appendix C). From Reference Table 13, the distance to 1 psi overpressure is 0.2 miles for 10,000 p ounds of ethylene; this distance would also apply to the 10,000-p ound mixture of ethylene and isobutane.

April 15, 1999 5 - 3Reference Table 1 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 10-Minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 4.4 0.1

4.4 - 37 0.2

37 - 97 0.3

97 - 180 0.4

180 - 340 0.6

340 - 530 0.8

530 - 760 1.0

760 - 1,000 1.2

1,000 - 1,500 1.4

1,500 - 1,900 1.6

1,900 - 2,400 1.8

2,400 - 2,900 2.0

2,900 - 3,500 2.2

3,500 - 4,400 2.4

4,400 - 5,100 2.6

5,100 - 5,900 2.8

5,900 - 6,800 3.0

6,800 - 7,700 3.2

7,700 - 9,000 3.4

9,000 - 10,000 3.6

10,000 - 11,000 3.8

11,000 - 12,000 4.0

12,000 - 14,000 4.2

14,000 - 15,000 4.4

15,000 - 16,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

16,000 - 18,000 4.8

18,000 - 19,000 5.0

19,000 - 21,000 5.2

21,000 - 23,000 5.4

23,000 - 24,000 5.6

24,000 - 26,000 5.8

26,000 - 28,000 6.0

28,000 - 29,600 6.2

29,600 - 35,600 6.8

35,600 - 42,000 7.5

42,000 - 48,800 8.1

48,800 - 56,000 8.7

56,000 - 63,600 9.3

63,600 - 71,500 9.9

71,500 - 88,500 11

88,500 - 107,000 12

107,000 - 126,000 14

126,000 - 147,000 15

147,000 - 169,000 16

169,000 - 191,000 17

191,000 - 215,000 19

215,000 - 279,000 22

279,000 - 347,000 25

>347,000 >25*

*Report distance as 25 miles

April 15, 1999 5 - 4Reference Table 2 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 60-Minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 5.5 0.1

5.5 - 46 0.2

46 - 120 0.3

120 - 220 0.4

220 - 420 0.6

420 - 650 0.8

650 - 910 1.0

910 - 1,200 1.2

1,200 - 1,600 1.4

1,600 - 1,900 1.6

1,900 - 2,300 1.8

2,300 - 2,600 2.0

2,600 - 2,900 2.2

2,900 - 3,400 2.4

3,400 - 3,700 2.6

3,700 - 4,100 2.8

4,100 - 4,400 3.0

4,400 - 4,800 3.2

4,800 - 5,200 3.4

5,200 - 5,600 3.6

5,600 - 5,900 3.8

5,900 - 6,200 4.0

6,200 - 6,700 4.2

6,700 - 7,000 4.4

7,000 - 7,400 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

7,400 - 7,700 4.8

7,700 - 8,100 5.0

8,100 - 8,500 5.2

8,500 - 8,900 5.4

8,900 - 9,200 5.6

9,200 - 9,600 5.8

9,600 - 10,000 6.0

10,000 - 10,400 6.2

10,400 - 11,700 6.8

11,700 - 13,100 7.5

13,100 - 14,500 8.1

14,500 - 15,900 8.7

15,900 - 17,500 9.3

17,500 - 19,100 9.9

19,100 - 22,600 11

22,600 - 26,300 12

26,300 - 30,300 14

30,300 - 34,500 15

34,500 - 38,900 16

38,900 - 43,600 17

43,600 - 48,400 19

48,400 - 61,500 22

61,500 - 75,600 25

>75,600 >25*

*Report distance as 25 miles

April 15, 1999 5 - 5Reference Table 3 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 10-minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 21 0.1

21 - 170 0.2

170 - 420 0.3

420 - 760 0.4

760 - 1,400 0.6

1,400 - 2,100 0.8

2,100 - 3,100 1.0

3,100 - 4,200 1.2

4,200 - 6,100 1.4

6,100 - 7,800 1.6

7,800 - 9,700 1.8

9,700 - 12,000 2.0

12,000 - 14,000 2.2

14,000 - 18,000 2.4

18,000 - 22,000 2.6

22,000 - 25,000 2.8

25,000 - 29,000 3.0

29,000 - 33,000 3.2

33,000 - 39,000 3.4

39,000 - 44,000 3.6

44,000 - 49,000 3.8

49,000 - 55,000 4.0

55,000 - 63,000 4.2

63,000 - 69,000 4.4

69,000 - 76,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

76,000 - 83,000 4.8

83,000 - 90,000 5.0

90,000 - 100,000 5.2

100,000 - 110,000 5.4

110,000 - 120,000 5.6

120,000 - 130,000 5.8

130,000 - 140,000 6.0

140,000 - 148,000 6.2

148,000 - 183,000 6.8

183,000 - 221,000 7.5

221,000 - 264,000 8.1

264,000 - 310,000 8.7

310,000 - 361,000 9.3

361,000 - 415,000 9.9

415,000 - 535,000 11

535,000 - 671,000 12

671,000 - 822,000 14

822,000 - 990,000 15

990,000 - 1,170,000 16

1,170,000 - 1,370,000 17

1,370,000 - 1,590,000 19

1,590,000 - 2,190,000 22

2,190,000 - 2,890,000 25

>2,890,000 >25*

*Report distance as 25 miles

April 15, 1999 5 - 6Reference Table 4 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 60-Minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 26 0.1

26 - 210 0.2

210 - 530 0.3

530 - 940 0.4

940 - 1,700 0.6

1,700 - 2,600 0.8

2,600 - 3,700 1.0

3,700 - 4,800 1.2

4,800 - 6,400 1.4

6,400 - 7,700 1.6

7,700 - 9,100 1.8

9,100 - 11,000 2.0

11,000 - 12,000 2.2

12,000 - 14,000 2.4

14,000 - 16,000 2.6

16,000 - 17,000 2.8

17,000 - 19,000 3.0

19,000 - 21,000 3.2

21,000 - 23,000 3.4

23,000 - 24,000 3.6

24,000 - 26,000 3.8

26,000 - 28,000 4.0

28,000 - 30,000 4.2

30,000 - 32,000 4.4

32,000 - 34,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

34,000 - 36,000 4.8

36,000 - 38,000 5.0

38,000 - 41,000 5.2

41,000 - 43,000 5.4

43,000 - 45,000 5.6

45,000 - 47,000 5.8

47,000 - 50,000 6.0

50,000 - 52,200 6.2

52,200 - 60,200 6.8

60,200 - 68,900 7.5

68,900 - 78,300 8.1

78,300 - 88,400 8.7

88,400 - 99,300 9.3

99,300 - 111,000 9.9

111,000 - 137,000 11

137,000 - 165,000 12

165,000 - 197,000 14

197,000 - 232,000 15

232,000 - 271,000 16

271,000 - 312,000 17

312,000 - 357,000 19

357,000 - 483,000 22

483,000 - 629,000 25

>629,000 >25*

*Report distance as 25 miles

April 15, 1999 5 - 7Reference Table 5Dense Gas Distances to Toxic Endpoint10-minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)12.21.71.51.10.80.70.50.50.30.20.20.20.10.1##23.02.42.11.51.10.90.70.70.40.30.30.20.20.1<0.1<0.154.83.73.02.21.71.51.21.00.70.50.40.30.30.20.10.1106.85.04.23.02.42.11.71.41.00.70.60.50.40.20.20.130118.76.85.23.93.42.82.41.71.31.10.90.70.40.30.25014119.36.85.04.23.53.02.21.71.41.10.90.60.40.31001915128.76.85.84.84.22.92.21.91.61.30.80.50.4150241815118.16.85.75.03.62.72.31.91.60.90.60.5250>25221914118.77.46.24.53.42.82.32.01.20.80.6500*>25>251914129.98.76.24.73.83.12.71.61.10.9750***23171512117.45.54.53.73.21.91.31.01,000***>25201714128.16.25.24.23.62.21.41.11,500 242016149.97.46.25.04.32.51.71.32,000** **>25231916118.76.85.64.82.91.91.52,500*****>252018129.38.16.25.33.22.11.63,000******2320149.98.76.85.63.42.21.74,000******>252216119.37.46.23.82.52.05,000*******251713118.76.84.22.72.17,500*******>252015129.98.74.93.22.510,000********241714119.35.53.62.815,000********>25201713116.24.23.220,000*********231915127.44.73.750,000*********>25>252118106.65.075,000***********>2521127.65.8100,000************24138.56.4150,000************>25159.87.4200,000*************17118.2*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)5 - 8Reference Table 6Dense Gas Distances to Toxic Endpoint60-minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)13.72.72.21.41.00.80.60.50.30.20.20.10.1<0.1##25.34.03.22.21.61.21.00.80.50.40.30.20.20.1<0.1<0.158.76.85.33.72.72.21.71.40.90.60.50.40.30.20.10.110129.38.15.34.03.32.72.21.41.00.80.60.50.30.20.1302216149.97.46.14.94.12.92.11.61.21.00.50.30.250>252118129.38.16.25.43.82.72.21.71.40.70.40.3100*>25>251813119.37.45.54.03.22.52.11.10.70.5150***221714119.96.84.94.03.12.71.40.90.6250***>25221814128.76.25.24.13.51.91.20.9500 >25252017129.37.45.85.02.91.81.3750** ***>25252215119.37.46.13.52.21.71,000******>25251712118.16.84.02.62.01,500*******>252016129.98.75.03.22.52,000********241714119.95.73.72.92,500********>25201613116.24.23.23,000*********211714126.84.53.54,000*********242016148.15.24.05,000*********>252217158.75.74.47,500**********>252118116.85.210,000***********2420127.46.015,000***********>2524149.36.820,000************>25169.98.150,000*************22141175,000*************>251713100,000**************1814150,000**************2116200,000**************2318*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)5 - 9Reference Table 7Dense Gas Distances to Toxic Endpoint10-minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)11.61.21.10.70.60.40.40.30.20.20.10.10.1###22.21.71.41.10.80.60.50.40.30.20.20.10.1<0.1##53.52.72.21.61.21.00.80.70.50.40.30.20.20.1<0.1#104.93.83.12.21.71.41.21.00.70.50.40.30.20.10.1<0.1308.16.25.33.72.92.42.01.71.20.90.70.60.40.20.10.150118.16.84.83.73.12.52.11.51.10.90.70.60.30.20.110015119.36.85.24.23.53.02.11.61.31.00.90.50.30.21501914128.16.15.24.33.62.51.91.61.21.10.60.40.2250241815118.16.85.44.63.32.42.01.61.40.70.50.3500>25>252115119.37.46.24.53.42.82.21.91.10.70.5750**>251814119.38.15.54.13.32.62.21.30.80.61,000***211613119.36.24.63.83.02.51.50.90.71,500***>25191612117.45.64.63.73.01.71.10.82,000 221815128.76.25.24.13.52.01.30.92,500** **242016149.96.85.84.73.82.21.41.13,000 >25221816117.46.25.04.22.41.61.24,000** ***252017128.76.85.64.82.71.71.35,000*****>252320149.98.16.25.33.01.91.47,500******>252416129.97.46.23.62.31.710,000*******>251914118.77.44.12.62.015,000********221613118.74.93.12.320,000********>251915129.95.53.52.750,000*********>252317158.15.13.875,000**********>2521179.66.04.5100,000***********2420116.85.1150,000***********>2523138.16.1200,000************>25148.96.7*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)5 - 10Reference Table 8Dense Gas Distances to Toxic Endpoint60-minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)12.61.91.51.10.70.60.40.40.20.20.10.10.1###23.82.92.31.51.10.90.70.60.40.20.20.10.1<0.1##56.24.73.92.61.91.51.20.90.60.40.30.20.20.1<0.1#109.36.85.63.92.92.31.81.50.90.70.50.40.30.20.1<0.13016129.97.45.34.33.42.91.91.31.00.70.60.30.20.1502216149.36.85.74.53.82.61.81.41.10.90.40.20.2100>252420149.98.16.85.73.82.72.21.71.40.70.40.3150*>25241712118.16.84.83.52.82.21.80.90.50.3250**>25221614119.36.24.53.72.92.41.20.70.5500***>25241916139.36.85.44.23.51.91.10.7750 >25241916118.16.85.24.32.41.41.01,000** ***>252219139.37.46.05.02.81.61.21,500******>252416129.37.46.23.42.11.52,000*******>251913118.77.44.02.51.82,500********2015129.38.14.52.82.13,000********221613118.74.93.02.24,000********>251916129.95.63.52.65,000*********211714116.24.03.07,500*********>252016147.44.83.610,000**********2419168.75.54.215,000**********>252219116.85.120,000***********>2521127.45.850,000************>2518118.775,000*************211310100,000*************241511150,000*************>251814200,000**************2015*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)5 - 11Reference Table 9 Distances to Toxic Endpoint for Anhydrous Ammonia Liquefied Under Pressure F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles)

(lbs/min)

Rural Urban

1 0.1 <0.1*

2 0.1 0.1

5 0.1 0.1

10 0.2 0.1

15 0.2 0.2

20 0.3 0.2

30 0.3 0.2

40 0.4 0.3

50 0.4 0.3

60 0.5 0.3

70 0.5 0.3

80 0.5 0.4

90 0.6 0.4

100 0.6 0.4

150 0.7 0.5

200 0.8 0.6

250 0.9 0.6

300 1.0 0.7

400 1.2 0.8

500 1.3 0.9

600 1.4 0.9

700 1.5 1.0

750 1.6 1.0

800 1.6 1.1

900 1.7 1.2 Release Rate Distance to Endpoint (miles) (lbs/min)

Rural Urban

1,000 1.8 1.2

1,500 2.2 1.5

2,000 2.6 1.7

2,500 2.9 1.9

3,000 3.1 2.0

4,000 3.6 2.3

5,000 4.0 2.6

6,000 4.4 2.8

7,000 4.7 3.1

7,500 4.9 3.2

8,000 5.1 3.3

9,000 5.4 3.4

10,000 5.6 3.6

15,000 6.9 4.4

20,000 8.0 5.0

25,000 8.9 5.6

30,000 9.7 6.1

40,000 11 7.0

50,000 12 7.8

75,000 15 9.5

100,000 18 10

150,000 22 13

200,000 ** 15

250,000 ** 17

750,000 ** **

*Report distance as 0.1 mile ** More than 25 miles (report distance as 25 miles)

April 15, 1999 5 - 12Reference Table 10 Distances to Toxic Endpoint for Non-liquefied Ammonia, Ammonia Liquefied by Refrigeration, or Aqueous Ammonia F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles)

(lbs/min)

Rural Urban

1 0.1

<0.1* 2 0.1

5 0.1

10 0.2 0.1

15 0.2 0.1

20 0.3 0.1

30 0.3 0.1

40 0.4 0.1

50 0.4 0.1

60 0.4 0.2

70 0.5 0.2

80 0.5 0.2

90 0.5 0.2

100 0.6 0.2

150 0.7 0.2

200 0.8 0.3

250 0.8 0.3

300 0.9 0.3

400 1.1 0.4

500 1.2 0.4

600 1.3 0.4

700 1.4 0.5

750 1.4 0.5

800 1.5 0.5

900 1.5 0.6 Release Rate Distance to Endpoint (miles) (lbs/min)

Rural Urban

1,000 1.6 0.6

1,500 2.0 0.7

2,000 2.2 0.8

2,500 2.5 0.9

3,000 2.7 1.0

4,000 3.1 1.1

5,000 3.4 1.2

6,000 3.7 1.3

7,000 4.0 1.4

7,500 4.1 1.5

8,000 4.2 1.5

9,000 4.5 1.6

10,000 4.7 1.7

15,000 5.6 2.0

20,000 6.5 2.4

25,000 7.2 2.6

30,000 7.8 2.8

40,000 8. 9 3.3

50,000 9.8 3.6

75,000 12 4.4

100,000 14 5.0

150,000 16 6.1

200,000 19 7.0

250,000 21 7.8

750,000 ** 13

*Report distance as 0.1 mile ** More than 25 miles (report distance as 25 miles)

April 15, 1999 5 - 13Reference Table 11 Distances to Toxic Endpoint for Chlorine F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles)

(lbs/min)

Rural Urban

1 0.2 0.1

2 0.3 0.1

5 0.5 0.2

10 0.7 0.3

15 0.8 0.4

20 1.0 0.4

30 1.2 0.5

40 1.4 0.6

50 1.5 0.6

60 1.7 0.7

70 1.8 0.8

80 1.9 0.8

90 2.0 0.9

100 2.2 0.9

150 2.6 1.2

200 3.0 1.3

250 3.4 1.5

300 3.7 1.6

400 4.2 1.9

500 4.7 2.1

600 5.2 2.3

700 5.6 2.5 Release Rate Distance to Endpoint (miles) (lbs/min)

Rural Urban

750 5.8 2.6

800 5.9 2.7

900 6.3 2.9

1,000 6.6 3.0

1,500 8.1 3.8

2,000 9.3 4.4

2,500 10 4.9

3,000 11 5.4

4,000 13 6.2

5,000 14 7.0

6,000 16 7.6

7,000 17 8.3

7,500 18 8.6

8,000 18 8.9

9,000 19 9.4

10,000 20 9.9

15,000 25 12

20,000 * 14

25,000 * 16

30,000 * 18

40,000 * 20

50,000 * *

* More than 25 miles (report distance as 25 miles)

April 15, 1999 5 - 14Reference Table 12 Distances to Toxic Endpoint for Anhydrous Sulfur Dioxide F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles)

(lbs/min)

Rural Urban

1 0.2 0.1

2 0.2 0.1

5 0.4 0.2

10 0.6 0.2

15 0.7 0.3

20 0.9 0.4

30 1.1 0.5

40 1.3 0.5

50 1.4 0.6

60 1.6 0.7

70 1.8 0.7

80 1.9 0.8

90 2.0 0.8

100 2.1 0.9

150 2.7 1.1

200 3.1 1.3

250 3.6 1.4

300 3.9 1.6

400 4.6 1.9

500 5.2 2.1

600 5.8 2.3

700 6.3 2.5 Release Rate Distance to Endpoint (miles) (lbs/min)

Rural Urban

750 6.6 2.6

800 6.8 2.7

900 7.2 2.9

1,000 7.7 3.1

1,500 9.6 3.8

2,000 11 4.5

2,500 13 5.0

3,000 14 5.6

4,000 17 6.5

5,000 19 7.3

6,000 21 8.1

7,000 23 8.8

7,500 24 9.1

8,000 25 9.5

9,000 * 10

10,000 * 11

15,000 * 13

20,000 * 16

25,000 * 18

30,000 * 19

40,000 * 23

50,000 * *

* More than 25 miles (report distance as 25 miles)

April 15, 1999 5 - 15Reference Table 13Distance to Overpressure of 1.0 psi for Vapor Cloud Explosions of500 - 2,000,000 Pounds of Regulated Flammable SubstancesBased on TNT Equivalent Method, 10 Percent Yield FactorQuantityin Cloud (pounds)5002,0005,00010,00020,00050,000100,000200,000500,0001,000,0002,000,000CAS No.Chemical NameDistance (Miles) to 1psi Overpressure75-07-0Acetaldehyde0.050.080.10.10.20.20.30.40.50.70.874-86-2Acetylene0.070.10.10.20.20.30.40.50.70.81.0598-73-2Bromotrifluoroethylene0.020.040.050.060.080.10.10.20.20.30.4106-99-01,3-Butadiene0.060.10.10.20.20.30.40.50.60.81.0106-97-8Butane0.060.10.10.20.20.30.40.50.60.81.025167-67-3Butene0.060.10.10.20.20.30.40.50.60.81.0590-18-12-Butene-cis0.060.10.10.20.20.30.40.50.60.81.0624-64-62-Butene-trans0.060.10.10.20.20.30.40.50.60.81.0106-98-91-Butene0.060.10.10.20.20.30.40.50.60.81.0107-01-72-Butene0.060.10.10.20.20.30.40.50.60.81.0463-58-1Carbon oxysulfide0.040.060.080.10.10.20.20.30.40.50.67791-21-1Chlorine monoxide0.020.030.040.050.060.080.10.10.20.20.3590-21-61-Chloropropylene0.050.080.10.10.20.20.30.40.50.60.8557-98-22-Chloropropylene0.050.080.10.10.20.20.30.40.50.60.8460-19-5Cyanogen0.050.080.10.10.20.20.30.40.50.60.875-19-4Cyclopropane0.060.10.10.20.20.30.40.50.60.81.04109-96-0Dichlorosilane0.040.060.080.10.10.20.20.30.40.50.675-37-6Difluoroethane0.040.060.090.10.10.20.20.30.40.50.6124-40-3Dimethylamine0.060.090.10.20.20.30.30.40.60.70.9463-82-12,2-Dimethylpropane0.060.10.10.20.20.30.40.50.60.81.074-84-0Ethane0.060.10.10.20.20.30.40.50.60.81.0107-00-6Ethyl acetylene0.060.10.10.20.20.30.40.50.60.81.075-04-7Ethylamine0.060.090.10.20.20.30.30.40.60.70.9April 15, 19995 - 16Reference Table 13 (continued)Quantityin Cloud (pounds)5002,0005,00010,00020,00050,000100,000200,000500,0001,000,0002,000,000CAS No.Chemical NameDistance (Miles) to 1psi Overpressure75-00-3Ethyl chloride0.050.080.10.10.20.20.30.40.50.60.874-85-1Ethylene0.060.10.10.20.20.30.40.50.70.81.060-29-7Ethyl ether0.060.090.10.20.20.30.30.40.60.70.975-08-1Ethyl mercaptan0.050.090.10.20.20.20.30.40.50.70.9109-95-5Ethyl nitrite0.050.070.10.10.20.20.30.30.50.60.71333-74-0Hydrogen0.090.10.20.20.30.40.50.60.91.11.475-28-5Isobutane0.060.10.10.20.20.30.40.50.60.81.078-78-4Isopentane0.060.10.10.20.20.30.40.50.60.81.078-79-5Isoprene0.060.10.10.20.20.30.40.50.60.81.075-31-0Isopropylamine0.060.090.10.20.20.30.30.40.60.70.975-29-6Isopropyl chloride0.050.080.10.10.20.20.30.40.50.60.874-82-8Methane0.070.10.10.20.20.30.40.50.70.81.074-89-5Methylamine0.060.090.10.20.20.30.30.40.60.70.9563-45-13-Methyl-1-butene0.060.10.10.20.20.30.40.50.60.81.0563-46-22-Methyl-1-butene0.060.10.10.20.20.30.40.50.60.81.0115-10-6Methyl ether0.050.090.10.10.20.30.30.40.50.70.9107-31-3Methyl formate0.040.070.10.10.20.20.30.30.40.60.7115-11-72-Methylpropene0.060.10.10.20.20.30.40.50.60.81.0504-60-91,3-Pentadiene0.060.10.10.20.20.30.40.50.60.81.0109-66-0Pentane0.060.10.10.20.20.30.40.50.60.81.0109-67-11-Pentene0.060.10.10.20.20.30.40.50.60.81.0646-04-82-Pentene, (E)-0.060.10.10.20.20.30.40.50.60.81.0627-20-32-Pentene, (Z)-0.060.10.10.20.20.30.40.50.60.81.0463-49-0Propadiene0.060.10.10.20.20.30.40.50.60.81.0April 15, 19995 - 17Reference Table 13 (continued)Quantityin Cloud (pounds)5002,0005,00010,00020,00050,000100,000200,000500,0001,000,0002,000,000CAS No.Chemical NameDistance (Miles) to 1psi Overpressure74-98-6Propane0.060.10.10.20.20.30.40.50.60.81.0115-07-1Propylene0.060.10.10.20.20.30.40.50.60.81.074-99-7Propyne0.060.10.10.20.20.30.40.50.60.81.07803-62-5Silane0.060.10.10.20.20.30.40.50.60.81.0116-14-3Tetrafluoroethylene0.020.030.040.050.070.090.10.10.20.20.375-76-3Tetramethylsilane0.060.10.10.20.20.30.40.50.60.81.010025-78-2Trichlorosilane0.030.040.060.080.10.10.20.20.30.40.479-38-9Trifluorochloroethylene0.020.030.050.060.070.10.10.20.20.30.375-50-3Trimethylamine0.060.10.10.20.20.30.40.40.60.81.0689-97-4Vinyl acetylene0.060.10.10.20.20.30.40.50.60.81.075-01-4Vinyl chloride0.050.080.10.10.20.20.30.40.50.60.8109-92-2Vinyl ethyl ether0.060.090.10.20.20.30.30.40.60.70.975-02-5Vinyl fluoride0.020.040.050.060.080.10.10.20.20.30.475-35-4Vinylidene chloride0.040.060.080.10.10.20.20.30.40.50.675-38-7Vinylidene fluoride0.040.060.090.10.10.20.20.30.40.50.6107-25-5Vinyl methyl ether0.060.090.10.20.20.30.30.40.60.70.9April 15, 19995 - 18

## 6 DETERMINING ALTERNATIVE RELEASE SCENARIOS

In Chapter 6

� Considerations for alternative release scenarios for regulated substances in Program 2 or Program 3 processes.

� Potential alternative scenarios for releases of flammable substances.

You are required to analyze at least one alternative release scenario for each listed toxic su bstance you have in a Program 2 or Program 3 process above its threshold quantity. You also are required to analyze one alternative release scenario for flammable substances in Program 2 or 3 processes as a class (i.e., you analyze one scenario involving a flammable su bstance as a representative scenario for all the re gulated flammable substances you have on site in Program 2 or Program 3 processes). You do not need to analyze an alternative scenario for each flammable substance. For example, if you have five listed substances – c hlorine, ammonia, hydrogen chloride, propane, and acetylene – above the threshold in Program 2 or 3 processes, you will need to analyze one alternative scenario each for chlorine, ammonia, and hydrogen chloride and a single alternative scenario to cover propane and acetylene (listed flammable substances). Even if you have a

substance above the thres hold in several processes or locations, you need only analyze one alternative

scenario for it.

According to the rule (40 CFR 68.28), alternative scenarios s hould be more likely to occur than the worst-case scenario and should reach an endpoint offsite, unless no such scenario exi sts. Release scenarios considered should include, but are not limited to, the following:

Transfer hose releases due to splits or sudden hose uncoupling; �

Process piping releases from failures at flanges, joints, welds, valves and valve seals, and drains or bleeds; �

Process vessel or pump releases due to cracks, seal failure, or drain, bleed, or plug failure; �

Vessel overfilling and spill, or overpressurization and venting through relief valves or rupture disks; and �

Shipping container mishandling or puncturing leading to a spill. �

Alternative release scenarios for toxic substances s hould be those that lead to concentrations above the toxic endpoint beyond your fenceline. Scenarios for flammable su bstances s hould have the potential to cause substantial damage, inc luding on-site damage. Those releases that have the potential to reach the public are of the greatest concern. You should consider unusual situations, such as start-up and shut-down, in selecting an appropriate alternative scenario.

For alternative release scenarios, you are allowed to consider active mitigation systems, such as interlocks, shutdown systems, pressure relieving devices, flares, emergency isolat ion systems, and fire water and deluge systems, as well as passive mitigation systems, as described in Sections 3.1.2 and 3.2.3.

For alternative release scenarios for regulated su bstances used in amm onia refrigeration, chemical distribution, propane distribution, warehouses, or POTWs, consult EPA's risk manag ement program guidance

April 15, 1999Chapter 6 Determining Alternative Release Scenarios

documents for these industry sectors.

You have a number of options for selecting release scenarios for toxic or flammable su bstances.

You may use your worst-case release scenario and apply your active mitigation system to limit the quantity released and the duration of the release. �

You may use information from your process h azards analysis, if you have c onducted one, to

select a scenario. �

You may review your accident history and choose an actual event as the basis of your

scenario. �

If you have not conducted a process h azards analysis, you may review your operat ions and identify possible events and failures. �

Whichever approach you select, the key information you need to define is the quantity to be released and the time over which it will be released; together, these allow you to estimate the release rate and use essentially the same methods you used for the worst-case analysis.

For flammable substances , the c hoice of alternative release scenarios is somewhat more complicated than for toxic substances, because the consequences of a release and the endp oint of concern may vary. For the flammable worst case, the consequence of concern is a vapor cloud explosion, with an overpressure endpoint. For alternative scenarios (e.g., fires), other endpoints (e.g., heat radiation) may need to be

considered.

Possible scenarios involving flammable su bstances inc lude:

Vapor cloud fires (flash fires) may result from dispersion of a cloud of flammable vapor and ignition of the cloud following dispersion. Such a fire could flash back and could represent a

severe heat radiation h azard to anyone in the area of the c loud. This guidance provides methods to estimate distances to a concentration equal to the lower flammability limit (LFL) for this type of fire. (See Sections 9.1, 9.2, and 10.1.) �

A pool fire, with potential radiant heat effects, may result from a spill of a flammable liquid. This guidance provides a simple method for estimating the distance from a pool fire to a radiant heat level that could cause second degree burns from a 40-second exposure. (See Section 10.2). �

A boiling liquid, expanding vapor explosion (BLEVE), leading to a fireball that may produce intense heat, may occur if a vessel containing flammable material ruptures explosively as a result of exposure to fire. Heat radiation from the fireball is the primary hazard; vessel fragments and overpressure from the explos ion also can result. BLEVEs are generally considered unlikely even ts; however, if you t hink a BLEVE is possible at your site, this guidance provides a method to estimate the distance at which radiant heat effects might lead to second degree burns. (See Section 10.3.) You also may want to consider models or �

April 15, 1999 6 - 2Chapter 6 Determining Alternative Release Scenarios

calculation methods to estimate effects of vessel fragmentat ion. (See Appendix A for references that may provide useful information for estimating such effects.)

For a vapor cloud explosion to occur, rapid release of a large quantity, turbulent conditions (caused by a turbulent release or congested conditions in the area of the release, or both), and other factors are generally necessary. Vapor cloud explosions generally are considered unlikely even ts; however, if c onditions at your site are conducive to vapor cloud explosions, you may want to consider a vapor cloud explosion as an alternative scenario. This guidance provides methods you may use to estimate the distance to 1 psi overpressure for a vapor cloud detonation, based on less conservative assumptions than the worst-case analysis. (See Section 10.4.) A vapor cloud deflagration, involving lower flame speeds than a detonation and resulting in less damaging blast effects, is more likely than a detonation. This guidance does not provide methods for estimating the effects of a deflagration, but you may use other methods of analysis if you want to consider such events. (See Appendix A for references that may provide useful information.) �

A jet fire may result from the puncture or rupture of a tank or pipeline containing a compressed or liquefied gas under pressure. The gas discharging from the hole can form a jet that "blows" into the air in the direction of the hole; the jet then may ignite. Jet fires could contribute to BLEVEs and fireballs if they impinge on tanks of flammable su bstances. A large horizontal jet fire may have the potential to pose an offsite hazard. This guidance does not include a method for estimating consequence distances for jet fires. If you want to consider a jet fire as an alternative scenario, you should consider other models or methods for the consequence analysis. (See Appendix A for references that may provide useful information.) �

If you carry out an alternative scenario analysis for a flammable mixture (i.e., a mixture that meets the criteria for NFPA 4), you need to consider all flammable components of the mixture, not just the regulated flammable substance or substances in the mixture (see Sect ion 5.2 on flammable mixtures). If the mixture contains both flammable and non-flammable components, the analysis should be c arried out consider ing only the flammable components.

Chapter 7 provides detailed information on calculating release rates for alternative release scenarios for toxic substances. If you can estimate release rates for the toxic gases and liq uids you have on site based on readily available information, you may skip Chapter 7 and go to Chapter 8. Chapter 8 describes how to estimate distances to the toxic endpoint for alternative scenarios for toxic su bstances. Chapters 9 pr ovides

information on calculation release rates for flammable su bstances. Chapter 10 describes how to estimate distances to flammable endpoints.

April 15, 1999 6 - 3Chapter 6 Determining Alternative Release Scenarios

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April 15, 1999 6 - 4

## 7 ESTIMATION OF RELEASE RATES FOR ALTERNATIVE

SCENARIOS FOR TOXIC SUBSTANCES

For the alternative scenario analysis, you may use typical meteorological conditions and typical ambient temperature and humidity for your site. This guidance assumes D atmospheric stability and wind speed of 3.0 meters per second (6.7 miles per hour) as conditions likely to be applicable to many sites.



### 7.1 Release Rates for Toxic Gases

In Section 7.1

� 7.1.1 Methods for unmitigated releases of toxic gases, including:

-- Release of toxic gas from a hole in a tank or pipe (for choked flow conditions, or maximum flow rate), -- Release of toxic gas from a pipe, based on the flow rate through the pipe, or based on a hole in the pipe (using the same method as for a hole in a tank), -- Puff releases (no method is provided; users are directed to use other methods), -- Gases liquefied under pressure, including gaseous releases from holes above the liquid level in the tank and releases from holes in the liquid space, and

-- Consideration of duration of releases of toxic gas.

� 7.1.2 Methods for adjusting the estimated release rate to account for active or passive mitigation, including:

-- Active mitigation to reduce the release duration (e.g., automatic shutoff valves),

-- Active mitigation to reduce the release rate to air, and

-- Passive mitigation (using the same method as for worst-case scenarios).



### 7.1.1 Unmitigated Releases of Toxic Gases

Gaseous Releases

Gaseous Release from Tank . Instead of assuming release of the entire contents of a vessel containing a toxic gas, you may decide to consider a more likely scenario as developed by the process h azards analysis, such as release from a hole in a vessel or pipe. To estimate a hole size you might assume, for example, the hole size that would result from shearing off a valve or pipe from a vessel containing a regulated su bstance. If you have a gas leak from a tank, you may use the following simplified equation to estimate a release rate based on hole size, tank pressure, and the properties of the gas. This equation applies to choked flow, or maximum gas flow rate. Choked flow generally would be expected for gases under pressure. (See Appendix D, Section D.6 for the derivation of this equation.)

April 15, 1999Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances



### QR � HA × P
t 

### × 1

T

t 

### × GF (7-1)

where: QR = Release rate (pounds per minute)

HA = Hole or puncture area (square inches) (from hazard evaluat ion or best estimate)

P

t = Tank pressure (pounds per square inch absolute (psi a)) (from process information; for liquefied gases, equilibrium vapor pressure at 25 C is o included in Exhibit B-1, Appendix B)

T

t = Tank temperature (K), where K is absolute temperature in kelvins; 25 C o (77 F) is 298 K o

GF = Gas Factor, incorporating discharge coefficient, ratio of specific heats, molecular weight, and conversion factors (listed for each regulated toxic gas in Exhibit B-1, Appendix B)

You can estimate the hole area from the size and shape of the hole. For a circular hole, you would

2 use the formula for the area of a circle (area = � r , where � is 3.14 and r is the radius of the circle; the radius is half the diameter).

This equation will give an estimate of the initial release rate. It will overestimate the overall release rate, because it does not take into account the decrease in the release rate as the pressure in the tank decreases. You may use a computer model or another calculation method if you want a more realistic estimate of the release rate. As discussed below, you may use this equation for releases of gases liquefied under pressure if the release would be primarily gas (e.g., if the hole is in the head space of the tank, well above the liquid level).

Example 19. Release of Toxic Gas from Tank (Diborane)

You have a tank that contains diborane gas at a pressure of 30 psia. The temperature of the tank and its contents is 298 K (25 � C). A valve on the side of the tank shears off, leaving a circular hole 2 1⁄2 inches in

2 diameter in the tank wall. You estimate the area from the formula for area of a circle ( � r , where r is the

2 radius). The radius of the hole is 1 1/4 inches, so the area is � × (1 1/4) , or 5 square inches. From Exhibit B-1, the Gas Factor for diborane is 17. Therefore, the release rate, from Equation 7-1, is:

QR = 5 × 30 × 1/(298) 1⁄2 × 17 = 148 p ounds per minute

Gaseous Release from Pipe . If shearing of a pipe may be an alternative scenario for a toxic gas at your site, you could use the usual flow rate through the pipe as the release rate and c arry out the estimat ion of distance as discussed in Chapter 8.

April 15, 1999 7 - 2Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

If you want to consider a release of toxic gas through a hole in a pipe as an alternative scenario, you may use the method described above for a gas release from a hole in a tank. This method neglects the effects of friction along the pipe and, therefore, provides a conservative estimate of the release rate.

Puff Releases . If a gaseous release from a hole in a tank or pipe is likely to be stopped very quickly (e.g., by a block valve), resulting in a puff of toxic gas that forms a vapor cloud rather than a plume, you may want to consider other methods for determining a consequence distance. A cloud of toxic gas resulting from a puff release will not exhibit the same behavior as a plume resulting from a longer release (e.g., a release over 10 minutes).

Liquefied Gases

Gases Liquefied Under Pressure . Gases liquefied under pressure may be released as gases, liquids, or a combination (two-phase), depending on a number of factors, including liquid level and the location of the hole relative to the liquid level. The resulting impact distances can vary greatly.

For releases from holes above the liquid level in a tank of gas liquefied under pressure, the release could be primarily gas, or the release may involve rapid vaporization of a fract ion of the liquefied gas andpossibly aerosolization (two-phase release). It is complex to determine which type of release (i.e., gas, twophase) will occur and the likely mix of gases and liquids in a two-phase release. The methods presented in this guidance do not definitively address this situation. As a rule of thumb, if the head space is large and the distance between the hole and the liquid level is relatively large given the height of the tank or vessel, you could assume the release is gaseous and, therefore, use Equation 7-1 above. (Exhibit B-1, Appendix B,

o includes the equilibrium vapor pressure in psia for listed toxic gases liquefied under pressure at 25 C; this pressure can be used in Equation 7-1.) However, use of this equation will not be conservative if the head space is small and the release from the hole is two-phased. In situations where you are unsure of whether the release would be gaseous or two-phase, you may want to consider other models or methods to c arry out a consequence analysis.

For a hole in the liquid space of a tank, you may use Equation 7-2 below to estimate the release rate.

o Exhibit B-1 in Appendix B gives the equilibrium vapor pressure in psia for listed toxic gases at 25 C; this is the pressure required to liquefy the gas at this temperature. You can estimate the gauge pressure in the tank from the equilibrium vapor pressure by subtracting the pressure of the ambient atmosphere (14.7 psi). Exhibit B-1 also gives the Density Factor (DF) for each toxic gas at its boiling point. This factor can be used

o to estimate the density of the liquefied gas (the density at 25 C would not be significantly different from the density at the boiling point for most of the listed gases). The equation to estimate the release rate is (see Appendix D, Section D.7.1, for more information):



### 11.7 669 QR � HA × 6.82 × LH � × P
g 

### (7-2) DF 2 

### DF

April 15, 1999 7 - 3Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

where: QR = Release rate (pounds per minute)

HA = Hole or puncture area (square inches) (from hazard evaluat ion or best estimate)

DF = Density Factor (listed for each regulated toxic gas in Exhibit B-1, Appendix B; 1/(DF x 0.033) is density in p ounds per cubic foot)

LH = Height of liquid column above hole (inches) (from hazard evaluat ion or best estimate)

P

g = Gauge pressure of the tank pressure (pounds per square inch gauge (psig), from vapor pressure of gas (listed in Exhibit B-1, Appendix B) minus atmospheric pressure (14.7 psi)

This equation gives the rate of release of liquid through the hole. For a gas liquefied under pressure, assume that the released liquid will i mmediately flash into vapor (or a vapor/aerosol mixture) and the release rate to air is the same as the liquid release rate. This equation gives an estimate of the initial release rate. It will overestimate the overall release rate, because it does not take into account the decrease in the release rate as the pressure in the tank and the height of the liquid in the tank decrease. You may use a computer model or another calculation method if you want a more realistic estimate of the release rate.

For a release from a broken pipe of a gas liquefied under pressure, see equations 7-4 to 7-6 below for liquid releases from pipes. Assume the released liquid flashes into vapor upon release and use the calculated

release rate as the release rate to air.

Gases Liquefied by Refrigeration . Gases liquefied by refrigeration alone may be treated as liquids. You may use the methods described in Section 7.2 for estimation of release rates.

Duration of Release

The duration of the release is used in choosing the appropriate generic reference table of distances, as discussed in Chapter 8. (You do not need to consider the duration of the release to use the chemical-specific reference tables.) You may calculate the maximum duration by dividing the quantity in the tank or the quantity that may be released from pipes by your calculated release rate. You may use 60 minutes as a default value for maximum release duration. If you know, and can su bstantiate, how long it is likely to take to stop the release, you may use that time as the release duration.



### 7.1.2 Mitigated Releases of Toxic Gases

For gases, passive mitigation may include enclosed spaces, as discussed in Section 3.1.2. Active mitigation for gases, which may be considered in analyzing alternative release scenarios, may include an assortment of techniques including automatic shutoff valves, rapid transfer systems ( emergency de inventory), and water/chemical sprays. These mitigation techniques have the effect of reducing either the release rate or the duration of the release, or both.

April 15, 1999 7 - 4Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

Active Mitigation

Active Mitigation to Reduce Release Duration . An example of a mitigation technique to reduce the release duration is automatic shutoff valves. If you have an estimate of the rate at which the gas will be released and the time it will take to shut off the release, you may estimate the quantity potentially released (release rate times time). You must be able to su bstantiate the time it w ill take to shut off the release. If the release will take place over a period of 10 minutes or more, you may use the release rate to estimate the distance to the toxic endpoint, as discussed in Chapter 8. For releases stopped in less than 10 minutes, multiply the initial release rate by the duration of release to estimate the quantity released, then divide the new quantity by 10 minutes to estimate a mitigated release rate that you may apply to the reference tables described in Chapter 8 to estimate the consequence distance. If the release would be stopped very quickly, you might want to consider other methods that will estimate consequence distances for a puff release.

Active Mitigation to Directly Reduce Release Rate to Air . Examples of mitigation techniques to directly reduce the release rate include scrubbers and flares. Use test data, manufacturer design specifications, or past experience to determine the fract ional reduction of the release rate by the mitigation technique. Apply this fract ion to the release rate that would have occurred without the mitigation technique. The initial release rate, without mitigation, may be the release rate for the alternative scenario (e.g., a release rate estimated from the equations presented earlier in this section) or the worst-case release rate. The mitigated release rate is:



### � � QR R 

### (1 FR )× QR (7-3)

where: QR R = Reduced release rate (pounds per minute)

FR = Fract ional reduction resulting from mitigation QR = Release rate without mitigation (pounds per minute)

Example 20. Water Spray Mitigation (Hydrogen Fluoride)

A bleeder valve on a hydrogen fluoride (HF) tank opens, releasing 660 p ounds per minute of HF. Water sprays are applied almost immediately. Experimental field and laboratory test data indicate that HF vapors could be reduced by 90 percent. The reduced release rate is:

QR R = (1 - 0.9) × (660 p ounds per minute) = 66 pounds per minute

In estimating the consequence distance for this release scenario, you would need to consider the release both before and after application of the water spray and determine which gives the greatest distance to the endpoint. You need to be able to substantiate the time needed to begin the water spray mitigation.

April 15, 1999 7 - 5Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

Passive Mitigation

The same simplified method used for worst-case releases may be used for alternative release scenarios to estimate the release rate to the outside air from a release in an enclosed space. For alternative scenarios, you may use a modified release quantity, if appropriate. You may also adjust the mitigation factor to account for the effects of ventilation, if appropriate for the alternative scenario you have chosen. Use the equations presented in Section 3.1.2 to estimate the release rate to the outside air.

Duration of Release

You should estimate the duration of the release either from your knowledge of the length of time it may take to stop the release (be prepared to substantiate your time estimate) or by dividing the quantity that may be released by your estimated release rate. (You do not need to consider the release duration to use the chemical-specific reference tables of distances.)



### 7.2 Release Rates for Toxic Liquids

In Section 7.2

� 7.2.1 Methods for estimating the liquid release rate and quantity released for toxic liquids released without mitigation, including:

-- Release of toxic liquid from a hole in a tank under atmospheric pressure (including toxic gases liquefied by refrigeration alone), -- Release of toxic liquid from a hole in the liquid space of a pressurized tank (the user is referred to equations provided in the section on toxic gases or in the technical appendix), and

-- Release of toxic liquid from a broken pipe.

� 7.2.2 Methods for estimating the liquid release rate and quantity released for toxic liquids released with mitigation measures that reduce the duration of the liquid release or the quantity of liquid released (e.g., automatic shutoff valves),

� 7.2.3 Methods for estimating the evaporation rate of toxic liquids from pools, accounting for:

-- Ambient temperature, -- Elevated temperature, -- Diked areas, -- Releases into buildings, -- Active mitigation to reduce the evaporation rate of the liquid,

o o -- Temperatures between 25 C and 50 C, and

-- Duration of the release.

� 7.2.4 Methods for estimating the evaporation rate for common water solutions of regulated toxic substances and for oleum.

April 15, 1999 7 - 6Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

This section describes methods for estimating liquid release rates from tanks and pipes. The released liquid is assumed to form a pool, and the evaporation rate from the pool is estimated as for the worst-case scenario. For the alternative scenario, you may assume the average wind speed in your area in the calculation of evaporation rate, instead of the worst-case wind speed of 1.5 meters per second (3.4 miles per hour). For the reference tables in this guidance, the wind speed for alternative scenarios is assumed to be 3.0 meters per second (6.7 miles per hour).

If you have sufficient information to estimate the quantity of liquid that might be released to an undiked area under an alternative scenario, you may go directly to Section 7.2.3 to estimate the evaporation rate from the pool and the release duration. After you have estimated the evaporation rate and release duration, go to Chapter 8 for instructions on estimating distance to the toxic endpoint.



### 7.2.1 Liquid Release Rate and Quantity Released for Unmitigated Releases

Release from Tank

Tank under Atmospheric Pressure . If you have a liquid stored in a tank at atmospheric pressure (including gases liquefied by refrigeration alone), you may use the following simple equation to estimate the liquid release rate from a hole in the tank below the liquid level. (See Appendix D, Section D.7.1, for the derivation of this equation.)



### QR L 

### � HA × LH × LLF (7-4)

where: QR L = Liquid release rate (pounds per minute)

HA = Hole or puncture area (square inches) (from hazard evaluat ion or best estimate)

LH = Height of liquid column above hole (inches) (from hazard evaluat ion or best estimate)

LLF = Liquid Leak Factor incorporating discharge coefficient and liquid density (listed for each toxic liquid in Exhibit B-2, Appendix B).

Remember that this equat ion only applies to liquids in tanks under atmospheric pressure. This equation will give an overestimate of the release rate, because it does not take into account the decrease in the release rate as the height of the liquid above the hole decreases. You may use a computer model or another calculation method if you want a more realistic estimate of the liquid release rate.

You may estimate the quantity that might be released by multiplying the liquid release rate from the above equation by the time (in minutes) that likely would be needed to stop the release. You should be able to substantiate the time needed to stop the release. Alternatively, you may assume the release w ould stop when the level of liquid in the tank drops to the level of the hole. You may estimate the quantity of liquid above that level in the tank from the dimensions of the tank, the liquid level at the start of the leak, and the level of the hole. Assume the estimated quantity is released into a pool and use the method and equations in Section 7.2.3 below to determine the evaporation rate of the liquid from the pool and the duration of the release. As discussed in Section 7.2.3, if you find that your estimated evaporation rate is greater than estimated liquid release rate, you should use the liquid release rate as the release rate to air.

April 15, 1999 7 - 7Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

Example 21. Liquid Release from Atmospheric Tank (Allyl Alcohol)

You have a tank that contains 20,000 p ounds of allyl alcohol at ambient temperature and pressure. A valve on the side of the tank shears, leaving a hole in the tank wall 5 square inches in area. The liquid column is 23 inches above the hole in the tank. From Exhibit B-2, the Liquid Leak Factor for allyl alcohol is 41. Therefore, from Equation 7-4, the liquid release rate is:

QR L = 5 × (23) 1⁄2 × 41 = 983 p ounds per minute

It takes 10 minutes to stop the release, so 10 minutes × 983 p ounds per minute = 9, 830 p ounds of allyl alcohol

released.

Pressurized Tank . If you have a liquid stored in a tank under pressure, you may estimate a release rate for liquid from a hole in the liquid space of the tank using the equation presented above for gases liquefied under pressure (Equation 7-2 in Section 7.1.1) or the equations in Appendix D, Section D.7.1.

Release from Pipe

If you have a liquid flowing through a pipe at approximately atmospheric pressure, and the pipeline remains at about the same height between the pipe inlet and the pipe break, you can estimate the quantity of liquid released from the flow rate in the pipe and the time it would take to stop the release by multiplying the flow rate by the time. For liquids at atmospheric pressure, assume the liquid is spilled into a pool and use the

methods in Section 7.2.3 below to estimate the release rate to air.

For the release of a liquid under pressure from a long pipeline, you may use the equations below (see Appendix D, Section D.7.2 for more information on these equations). These equations apply both to substances that are liq uid at ambient conditions and to gases liquefied under pressure. This method does not consider the effects of friction in the pipe. First estimate the initial operational flow velocity of the su bstance through the pipe using the initial operational flow rate as follows:



### FR × DF × 0.033 V �

a 

### (7-5) A

p

where: V

a = Initial operational flow velocity (feet per minute)

FR = Initial operational flow rate (pounds per minute)

DF = Density Factor (from Exhibit B-2, Appe ndix B)

A

p = Cross-sectional area of pipe (square feet)

You can estimate the cross-sectional area of the pipe from the diameter or radius (half the diameter

2 of the pipe) using the formula for the area of a circle (area = � r , where r is the radius).

The release velocity is then calculated based on the initial operational flow, any gravitational

April 15, 1999 7 - 8Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

accelerat ion or d ecelerat ion effects resulting from changes in the height of the pipeline, and the pressure difference between the pressure in the pipe and atmospheric pressure, using a form of the Bernoulli equation:



### � 197 × [28.4 × ( P T 

### 14.7) × DF ] � [5.97 × ( Z )] � [2.58×10

� 5 

### × V

� � V

b a 

### Z b a 2 

### ] (7-6)

where: V b = Release velocity (feet per minute)

P T = Total pressure on liquid in pipe (psia)

DF = Density factor, see Exhibit B-1 or Exhibit B-2

Z

a = Height of pipeline at inlet (feet)

Z

b = Height of pipeline at break (feet)

V

a = Operational velocity (feet per minute), calculated from Equation 7-5

Please note that if the height of the pipe at the release point is higher than the initial pipe height, then Z -Z is a b negative, and the height term will cause the estimated release velocity to decrease.

The release velocity can then be used to calculate a release rate as follows:



### V

b 

### × A
p


### � QR L 

### (7-7) DF × 0.033

where: QR L = Release rate (pounds per minute)

V

b = Release velocity (feet per minute)

DF = Density Factor

A

p = Cross-sectional area of pipe (square feet)

You may estimate the quantity released into a pool from the broken pipe by multiplying the liquid release rate (QR ) from the equation above by the time (in minutes) that likely would be needed to stop the L release (or to empty the pipeline). Assume the estimated quantity is released into a pool and use the method and equations described in Section 7.2.3 below to determine the evaporation rate of the liquid from the pool.

You must be able to su bstantiate the time needed to stop the release.

As noted above in Section 7.1.1, for a release from a pipe of gas liquefied under pressure, assume that the released liquid is immediately vaporized, and use the calculated liquid release rate as the release rate to air. If the release duration would be very short (e.g., because of active mitigation measures), determine the total quantity of the release as the release rate times the duration, then estimate a new release rate as the quantity divided by 10. This will give you a release rate that you can use with the 10-minute reference tables of distances in this guidance to estimate a distance to the endpoint.

In the case of very long pipes, release rates from a shear or hole will be lower than the estimates from this method because of pipe roughness and frictional head loss. If friction effects are d eemed considerable, an established method for calculating frictional head loss such as the Darcy formula may be used.

April 15, 1999 7 - 9Chapter 7

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### 7.2.2 Liquid Release Rate and Quantity Released for Mitigated Releases

For alternative release scenarios, you are permitted to take credit for both passive and active mitigation systems, or a combination if both are in place. Active mitigation techniques that reduce the rate of liquid release or the quantity released into the pool are discussed in this section. Active and passive mitigation to reduce the evaporation rate of liquid from a pool are discussed in the next section.

Active Mitigation to Red uce Quan tity Released

Examples of mitigation techniques to reduce the quantity released into the pool include automatic shutoff valves and emergency de inventory. You may use the equations in Section 7.2.1 above for calculating liquid release rate, if applicable. Estimate the approximate time needed to stop the release by the mitigation technique (you must be able to justify your estimate). Multiply the release rate times the duration of release to estimate quantity released. Assume the estimated quantity is released into a pool and use the method and equations described in Section 7.2.3 below to determine the evaporation rate of the liquid from the pool. You should also consider mitigation (active or passive) of evaporation from the pool, if applicable, as discussed in

Section 7.2.3 below.

Example 22. Mitigated Liquid Release

A bromine injection system suffers a hose failure; the greatly lowered system pressure triggers an automatic shutoff valve within 30 seconds of the release. The flow rate out of the ruptured hose is approximately 330 pounds per minute. Because the release occurred for only 30 seconds (0.5 minutes), the total quantity spilled was 330 x 0.5, or 165 p ounds.



### 7.2.3 Evaporation Rate from Liquid Pool

After you have estimated the quantity of liquid released, assume that the liquid forms a pool and calculate the evaporation rate from the pool as described below. You may account for both passive and active mitigation in estimating the release rate. Passive mitigation may include techniques already discussed in Section 3.2.3 such as dikes and trenches. Active mitigation to reduce the release rate of liquid in pools to the air may include an assortment of techniques including foam or tarp coverings and water or chemical sprays. Some methods of accounting for passive and active mitigation are discussed below.

If the calculated evaporation rate from the pool is greater than the liquid release rate you have estimated from the container, no pool would be formed, and calculating the release rate as the evaporation rate from a pool would not be appropriate. If the pool evaporation rate is greater than the liquid release rate, use the liquid release rate as the release rate to air. Consider this possibility particularly for relatively volatile liquids, gases liquefied by refrigeration, or liquids at elevated temperature that form pools with no mitigation.

April 15, 1999 7 - 10Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

Unmitigated

Ambient temperature . For pools with no mitigation, if the liquid is always at ambient temperature, find the Liquid Factor Ambient (LFA) and the Density Factor (DF) in Exhibit B-2 of Appendix B (see

o Appendix D, Section D.2.2 for the derivation of these factors). If your ambient temperature is between 25 C

o and 50 C, you may use this method to calculate the release rate, and then use the appropriate Temperature Correction Factor from Exhibit B-4, Appendix B, to adjust the release rate, as described below. For gases liquefied by refrigeration, use the Liquid Factor Boiling (L FB) and DF from Exhibit B-1. Calculate the release rate from the following equation for liquids at ambient temperature with no mitigation:



### QR QS × 2.4 × LFA × DF (7-8) �

where: QR = Release rate (pounds per minute) QS = Quantity released (pounds)

2.4 = Wind speed factor = 3.0 0.78 , where 3.0 meters per second (6.7 miles per hour) is the wind speed for the alternative scenario for purposes of this guidance

LFA = Liquid Factor Ambient

DF = Density Factor

This method assumes that the total quantity of liquid released spreads out to form a pool one centimeter in depth; it does not take into account evaporation as the liquid is released.

Example 23. Evaporation from Pool Formed by Liquid Released from Hole in Tank (Allyl Alcohol)

In Example 21, 9,830 p ounds of allyl alcohol were estimated to be released from a hole in a tank. From Exhibit B-2, the Density Factor for allyl alcohol is 0.58, and the Liquid Factor Ambient is 0. 0046. Assuming that the liquid is not released into a diked area or inside a building, the evaporation rate from the pool of allyl alcohol, from Equation 7-8, is:

QR = 9,830 × 2.4 × 0.0046 × 0.58 = 63 p ounds per minute

Elevated temperature . For pools with no mitigation, if the liquid is at an elevated temperature (above

o 50 C or at or close to its boiling point), find the Liquid Factor Boiling (L FB) and the Density Factor (DF) in Exhibit B-2 of Appendix B (see Appendix D, Section D.2.2, for the derivation of these factors). For liquids

o o at temperatures between 25 C and 50 C, you may use the method above for ambient temperature and apply the appropriate Temperature Correction Factor from Appendix B, Exhibit B-4, to the result, as discussed

o below. For liquids above 50 C, or close to their boiling points, or with no Temperature Correction Factors available, calculate the release rate of the liquid from the following equation:



### QR QS × 2.4 × LFB × DF (7-9) �

April 15, 1999 7 - 11Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

where: QR = Release rate (pounds per minute) QS = Quantity released (pounds)

2.4 = Wind speed factor = 3.0 0.78 , where 3.0 meters per second (6.7 miles per hour) is the wind speed for the alternative scenario for purposes of this guidance

LFB = Liquid Factor Boiling

DF = Density Factor

Mitigated

Diked Areas . If the toxic liquid will be released into an area where it will be contained by dikes, compare the diked area to the maximum area of the pool that could be formed, as described in Section 3.2.3 (see Equation 3-6). Also verify that the quantity spilled will be totally contained by the dikes. The smaller of the two areas should be used in determination of the evaporation rate. If the maximum area of the pool is smaller than the diked area, calculate the release rate as described for pools with no mitigation (above). If the diked area is smaller, and the spill will be totally contained, go to Exhibit B-2 in Appendix B to find the Liquid Factor Ambient (LFA), if the liquid is at ambient temperature, or the Liquid Factor Boiling (L FB), if

o o the liquid is at an elevated temperature. For temperatures between 25 C and 50 C, you may use the appropriate Temperature Correction Factor from Exhibit B-4, Appendix B, to adjust the release rate, as described below. For gases liquefied by refrigeration, use the LFB. Calculate the release rate from the diked area as follows for liquids at ambient temperature:



### QR � 2.4 × LFA × A (7-10)

or, for liquids at elevated temperatures or gases liquefied by refrigeration alone:



### QR � 2.4 × LFB × A (7-11)

where: QR = Release rate (pounds per minute)

2.4 = Wind speed factor = 3.0 0.78 , where 3.0 meters per second (6.7 miles per hour) is the wind speed for the alternative scenario for purposes of this guidance

LFA = Liquid Factor Ambient (listed in Exhibit B-2, Appendix B)

LFB = Liquid Factor Boiling (listed in Exhibit B-1 or B-2, Appendix B)

A = Diked area (square feet)

Releases Into Buildings . If a toxic liquid is released inside a building, compare the area of the building floor or any diked area that would contain the spill to the maximum area of the pool that could be formed; the smaller of the two areas should be used in determining the evaporation rate, as for the worst-case scenario. The maximum area of the pool is determined from Equation 3-6 in Section 3.2.3 for releases into diked areas. The area of the building floor is the length times width of the floor (in feet) (Equation 3-9).

If the floor area or diked area is smaller than the maximum pool size, estimate the outdoor evaporation rate from a pool the size of the floor area or diked area from Equation 7-10. If the maximum pool area is smaller, estimate the outdoor evaporation rate from a pool of maximum size from Equation 7-8.

April 15, 1999 7 - 12Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances

Estimate the rate of release of the toxic vapor from the building as five percent of the calculated outdoor evaporation rate (multiply your evaporation rate by 0.05). See Appendix D, Section D.2.4 for more information on releases into buildings.

Active Mitigation to Reduce Evaporation Rate . Examples of active mitigation techniques to reduce the evaporation rate from the pool include water sprays and foam or tarp covering. Use test data, manufacturer design specifications, or past experience to determine the fract ional reduction of the release rate by the mitigation technique. Apply this fract ion to the release rate (evaporation rate from the pool) that would have occurred without the mitigation technique, as follows:



### � QR RV 

### (1

� FR )× QR (7-12)

where: QR RV = Reduced evaporation rate (release rate to air) from pool (pounds per minute)

FR = Fract ional reduction resulting from mitigation QR = Evaporation rate from pool without mitigation (pounds per minute)

o Temperature Corrections for Liquids at Temperatures bet ween 25 and 50 C

o o o o If your liquid is at a temperature between 25 C (77 F) and 50 C ( 122 F), you may use the appropriate Temperature Correction Factor (T CF) from Exhibit B-4, Appe ndix B, to calculate a corrected

o o release rate. Calculate the release rate (QR) of the liquid at 25 C (77 F) as described above for unmitigated releases or releases in diked areas and multiply the release rate by the appropriate TCF as described in

Section 3.2.5.

Evaporation Rate Compared to Liquid Release Rate

If you estimated the quantity of liquid in the pool based on an estimated liquid release rate from a hole in a container or pipe, as discussed in Sections 7.2.1 and 7.2.2, compare the evaporation rate with the liquid release rate. If the evaporation rate from the pool is greater than the liquid release rate, use the liquid

release rate as the release rate to air.

Duration of Release

After you have estimated a release rate as described above, determine the duration of the vapor release from the pool (the time it will take for the liquid pool to evaporate completely). To estimate the time in minutes, divide the total quantity released (in pounds) by the release rate (in pounds per minute) (see Equation 3-5 in Section 3.2.2). If you are using the liquid release rate as the release rate to air, as discussed in the preceding p aragraph, estimate a liq uid release duration as discussed in Section 7.2.1 or 7.2.2. The duration could be the time it would take to stop the release or the time it would take to empty the tank or to release all the liquid above the level of the leak. If you have corrected the release rate for a temperatures

o above 25 C, use the corrected release rate to estimate the duration.

April 15, 1999 7 - 13Chapter 7

Estimation of Release Rates for Alternative Scenarios for Toxic Substances



### 7.2.4 Common Water Solutions and Oleum

You may use the methods described above in Sections 7.2.1, 7.2.2, and 7.2.3 for pure liquids to estimate the quantity of a solution of a toxic su bstance or oleum that may be sp illed into a pool. LFA, DF, and LLF values for several concentrations of ammonia, formaldehyde, hydrochloric acid, hydrofluoric acid, and nitric acid in water solution and for oleum are listed in Appendix B, Exhibit B-3. The LFA for a wind speed of 3.0 meters per second (6.7 miles per hour) should be used in the release rate calculations for alternative scenarios for pools of solutions at ambient temperature.

For unmitigated releases or releases with passive mitigation, follow the instructions in Section 7.2.3. If active mitigation measures are in place, you may estimate a reduced release rate from the instructions on active mitigation in Section 7.2.2. Use the total quantity of the solution as the quantity released from the vessel or pipeline (QS) in c arry ing out the calculation of the release rate to the atmosphere.

If the solution is at an elevated temperature, see Section 3.3. As discussed in Section 3.3, you may

treat the release of the substance in s olution as a release of the pure su bstance. Alternatively, if you have vapor pressure data for the solution at the release temperature, you may estimate the release rate from the equations in Appendix D, Sections D.2.1 and D.2.2.

If you estimated the quantity of solution in the pool based on an estimated liquid release rate from a hole in a container or pipe, as discussed in Sections 7.2.1 and 7.2.2, compare the evaporation rate with the liquid release rate. If the evaporation rate from the pool is greater than the liquid release rate, use the liquid

release rate as the release rate to air.

April 15, 1999 7 - 14

## 8 ESTIMATION OF DISTANCE TO THE ENDPOINT FOR

ALTERNATIVE SCENARIOS FOR TOXIC SUBSTANCES

In Chapter 8

� Reference tables of distances for alternative releases, including:

-- Generic reference tables (Exhibit 4), and -- Chemical-specific reference tables (Exhibit 5).

� Considerations include:

-- Gas density (neutrally buoyant or dense), -- Duration of release (10 minutes or 60 minutes), -- Topography (rural or urban).

For estimating consequence distances for alternative scenarios for toxic su bstances, this guidance provides four generic reference tables for neutrally buoyant gases and vapors and four for dense gases. The generic reference tables of distances (Reference Tables 14-21) are found at the end of Chapter 10. Thegeneric tables and the conditions for which each table is applicable are described in Exhibit 4. Four chemicalspecific tables also are provided for ammonia, chlorine, and sulfur dioxide. The chemical-specific reference tables follow the generic reference tables at the end of Chapter 10. These tables, and the applicable conditions, are described in Exhibit 5.

All the reference tables of distances for alternative scenarios were developed assuming D stability and a wind speed of 3.0 meters per second (6.7 miles per hour) as representative of likely conditions for many sites. Many wind speed and atmospheric stability combinations may be possible at different times in different parts of the country. If D stability and 3.0 meters per second are not reasonable conditions for your site, you may want to use other methods to estimate distances.

For simplicity, this guidance assumes ground level releases. This guidance, therefore, may overestimate the consequence distance if your alternative scenario involves a release above ground level, particularly for neutrally buoyant gases and vapors. If you want to assume an elevated release, you may want to consider other methods to determine the consequence distance.

The generic reference tables should be used for all toxic su bstances other than amm onia, chlorine, and sulfur dioxide. To use the generic reference tables, you need to consider the release rates estimated for gases and evaporation from liquid pools and the duration of the release. For the alternative scenarios, the duration of toxic gas releases may be longer than the 10 minutes assumed for the worst-case analysis for gases. You need to determine the appropriate toxic endpoint and whether the gas or vapor is neutrally buoyant or dense, using the tables in Appendix B and considering the conditions of the release. You may interpolate between entries in the reference tables.

April 15, 1999Chapter 8 Estimation of Distance to the Endpoint for Alternative Scenarios for Toxic Substances

Exhibit 4

Generic Reference Tables of Distances for Alternative Scenarios

Applicable Conditions Reference Table

Number Gas or Vapor Density Topography Release Duration (minutes)

Neutrally buoyant Rural 10 14

60 15

Urban 10 16

60 17

Dense Rural 10 18

60 19

Urban 10 20

60 21

Exhibit 5 Chemical-Specific Reference Tables of Distances for Alternative Scenarios

Substance Conditions of Release

Table Reference

Number Gas or Vapor Density Release Duration (minutes) Topography

Anhydrous ammonia liquefied under pressure Dense 10-60 Rural, urban 22

Non-liquefied ammonia, ammonia liquefied by refrigeration, or aqueous

ammonia Neutrally buoyant 10-60 Rural, urban 23

Chlorine Dense 10-60 Rural, urban 24

Sulfur dioxide (anhydrous) Dense 10-60 Rural, urban 25

April 15, 1999 8 - 2Chapter 8 Estimation of Distance to the Endpoint for Alternative Scenarios for Toxic Substances

Note the following concerning the use of the chemical-specific reference tables for ammonia, chlorine, and sulfur dioxide:

The table for anhydrous ammonia (Reference Table 22) applies only to flashing releases of ammonia liquefied under pressure. Use Table 23 for release of ammonia as a gas (e.g., evaporation from a pool or release from the vapor space of a tank). �

You may use these tables for releases of any duration. �

To use the reference tables of distances, follow these steps:

For Regulated Toxic Substa nces Other than Ammonia, Ch lorine, and Sulfur Dioxide

Find the toxic endpoint for the su bstance in Appe ndix B (Exhibit B-1 for toxic gases or Exhibit B-2 for toxic liquids). �

Determine whether the table for neutrally buoyant or dense gases and vapors is appropriate from Appendix B (Exhibit B-1 for toxic gases or Exhibit B-2, column for alternative case, for toxic liquids). A toxic gas that is lighter than air may behave as a dense gas upon release if it is liquefied under pressure, because the released gas may be mixed with liquid droplets, or if it is cold. Consider the state of the released gas when you decide which table is appropriate. �

Determine whether the table for rural or urban conditions is appropriate. �

-- Use the rural table if your site is in an open area with few obstruct ions.

-- Use the urban table if your site is in an urban or obstructed area.

Determine whether the 10-minute table or the 60-minute table is appropriate. �

-- Use the 10-minute table for releases from evaporating pools of common water

solutions and of oleum.

-- If you estimated the release duration for gas release or pool evaporation to be 10 minutes or less, use the 10-minute table.

-- If you estimated the release duration for gas release or pool evaporation to be more than 10 minutes, use the 60-minute table.

Neutrally Buoyant Gases or Vapors

If Exhibit B-1 or B-2 indicates the gas or vapor should be considered neutrally buoyant, and other factors would not cause the gas or vapor to behave as a dense gas, divide the estimated release rate (pounds per minute) by the toxic endpoint (milligrams per liter). �

April 15, 1999 8 - 3Chapter 8 Estimation of Distance to the Endpoint for Alternative Scenarios for Toxic Substances

Find the range of release rate/toxic endpoint values that includes your calculated release rate/toxic endpoint in the first column of the appropriate table (Reference Table 14, 15, 16, or 17), then find the corresponding distance to the right. �

Dense Gases or Vapors

If Exhibit B-1 or B-2 or consideration of other relevant factors indicates the su bstance should be considered a dense gas or vapor (heavier than air), find the distance in the appropriate table (Reference Table 18, 19, 20, or 21) as follows; �

-- Find the toxic endpoint closest to that of the su bstance by rea ding across the top of the table. If the endpoint of the su bstance is halfway between two values on the table, choose the value on the table that is smaller (to the left). Otherwise, choose the closest value to the right or the left.

-- Find the release rate closest to the release rate estimated for the su bstance at the left of the table. If the calculated release rate is halfway between two values on the table, choose the release rate that is larger (farther down on the table). Otherwise, choose the closest value (up or down on the table).

-- Read across from the release rate and down from the endpoint to find the distance corresponding to the toxic endpoint and release rate for your su bstance.

For Ammonia, Ch lorine, or Sulfur Dioxide

Find the appropriate chemical-specific table for your su bstance (see the descript ions of Reference Tables 22-25 in Exhibit 5). �

-- If you have ammonia liquefied by refrigeration alone, you may use Reference Table 23, even if the duration of the release is greater than 10 minutes.

-- If you have chlorine or sulfur dioxide liquefied by refrigeration alone, you may use the chemical-specific reference tables, even if the duration of the release is greater

than 10 minutes.

Determine whether rural or urban topography is applicable to your site. �

-- Use the rural column in the reference table if your site is in an open area with few

obstruct ions.

-- Use the urban column if your site is in an urban or o bstructed area.

Estimate the consequence distance as follows: �

-- In the left-hand column of the table, find the release rate closest to your calculated

release rate.

April 15, 1999 8 - 4Chapter 8 Estimation of Distance to the Endpoint for Alternative Scenarios for Toxic Substances

-- Read the corresponding distance from the appropriate column (urban or rural) to the right.

The development of the generic reference tables is discussed in Appendix D, Sections D.4.1 and

D.4.2. The development of the chemical-specific reference tables is discussed in industry-specific risk
management program guidance documents and a backup information document that are cited in Section

D.4.3. If you think the results of the method presented here overstate the potential consequences of a your alternative release scenario, you may choose to use other methods or models that take additional site-specific

factors into account.

Examples 24 and 25 below include the results of modeling using two other models, ALOHA and WHAZAN, for comparison with the results of the methods presented in this guidance. Appendix D, Section

D.4.5 provides additional information on this modeling.

Example 24. Gas Release of Chlorine

Assume that you calculated a release rate of 500 p ounds per minute of chlorine from a tank. A chemicalspecific table is provided for chlorine, so you do not need to consult Appendix B for information on chlorine. The topography of your site is urban. For a release of chlorine under average meteorology (D stability and 3 meters per second wind speed), go to Reference Table 24. The estimated release rate of 500 p ounds per minute, with urban topography, corresponds to a consequence distance of 0.4 miles.

Additional Modeling for Comparison

The ALOHA model gave a distance of 3.0 miles to the endpoint, using the same assumptions.

The WHAZAN model gave a distance of 3.2 miles to the endpoint, using the same assumptions and the dense cloud dispersion model.

April 15, 1999 8 - 5Chapter 8 Estimation of Distance to the Endpoint for Alternative Scenarios for Toxic Substances

Example 25. Allyl Alcohol Evaporating from Pool

In Example 23, the evaporation rate of allyl alcohol from a pool was calculated as 63 pounds per minute. The total quantity in the pool was estimated as 9, 830 p ounds; therefore, the pool would evaporate in 9, 830/63 or 156 minutes. You would use a 60-minute reference table to estimate the distance to the endpoint. From Exhibit B-2 in Appendix B, the toxic endpoint for allyl alcohol is 0. 036 mg/L, and the appropriate reference table for the alternative scenario analysis is a neutrally buoyant plume table. To find the distance from the neutrally buoyant plume tables, you need the release rate divided by the endpoint. In this case, it is 63/0.036, or 1,750. Assuming the release takes place in a rural location, you use Reference Table 15, applicable to neutrally buoyant plumes, 60

- minute releases, and rural conditions. From this table, you estimate the distance as 0.4 mile.

Additional Modeling for Comparison

The ALOHA model gave a distance of 0.7 mile to the endpoint for a release rate of 63 pounds per minute, using the same assumptions and the dense gas model.

The WHAZAN model gave a distance of 0.5 mile to the endpoint for a release rate of 63 pounds per minute, using the same assumptions and the buoyant plume dispersion model.

April 15, 1999 8 - 6

## 9 ESTIMATION OF RELEASE RATES FOR ALTERNATIVE

SCENARIOS FOR FLAMMABLE SUBSTANCES

In Chapter 9

� Methods to estimate a release rate to air for a flammable gas (9.1) or liquid (9.2).



### 9.1 Flammable Gases

Gaseous Release from Tank or Pipe

An alternative scenario for a release of a flammable gas may involve a leak from a vessel or piping. To estimate a release rate for flammable gases from hole size and storage conditions, you may use the method described above in Section 7.1.1 for toxic gases. This release rate may be used to determine the dispersion distance to the lower flammability limit (LFL), as described in Section 10.1. Exhibit C-2 in Appendix C includes Gas Factors (GF) that may be used in c arry ing out the calculations for each of the regulated flammable gases.

Example 26. Release Rate of Flammable Gas from Hole in Tank (Ethylene)

A pipe tears off a tank containing ethylene. The pipe is in the vapor space of the tank. The release rate from the hole can be estimated from Equation 7-1 in Section 7.1. You estimate that the pipe would leave a hole with an area (HA) of 5 square inches. The temperature inside the tank (T , absolute temperature, Kelvin) is 282 K,

t 9 � C, and the square root of the temperature is 16.8. The pressure in the tank (P ) is approximately 728 p ounds

t per square inch absolute (psia). From Exhibit C-2, Appendix C, the gas factor (GF) for ethylene is 18. From Equation 7-1, the release rate (QR) is:

QR = 5 × 728 × (1/16.8) × 18 = 3,900 p ounds per minute

Gases Liquefied Under Pressure

A vapor cloud fire is a possible result of a release of a gas liquefied under pressure. You may use the methods described in Section 7.1.1 for toxic gases liquefied under pressure to estimate the release rate from a hole in a tank for a flammable gas liquefied under pressure. The estimated release rate may be used to estimate the dispersion distance to the LFL for a vapor cloud fire.

Flammable gases that are liquefied under pressure may be released very rapidly, with partial vaporization of the liquefied gas and possible aerosol formation. Section 10.4 presents a method for estimating the consequences of a vapor cloud explosion from such a release of a gas liquefied under pressure.

April 15, 1999Chapter 9

Estimation of Release Rates for Alternative Scenarios for Flammable Substances

Gases Liquefied by Ref rigeration

Flammable gases liquefied by refrigeration alone can be treated as liquids for the alternative scenario analysis, as discussed in Section 9.2 and Section 10.2, below.



### 9.2 Flammable Liquids

You may estimate a release rate for flammable liquids by estimating the evaporation rate from a pool. Release rates also can be estimated for flammable gases liquefied by refrigeration alone by this method, if the liquefied gas is likely to form a pool upon release. You first need to estimate the quantity in the pool.

You may use the method discussed in Section 7.2.1 to estimate a rate of liquid release for flammable liquids into a pool from a hole in a tank or from a pipe shear. Exhibit C-3 in Appendix C includes liquid leak factors (LLF) for calculating release rate from a hole. Note that the LLF is appropriate only for atmospheric tanks. LLF values are not provided for liquefied flammable gases; you will need to estimate the quantity in the pool from other information for liquefied flammable gases.

Once you have an estimate of the quantity of flammable liquid in a pool, you may use the methods presented in Section 7.2.3 to estimate the evaporation rate from the pool. Liquid factors at ambient and boiling temperature (LFA and L FB) for liq uids for the calculation are listed in Exhibit C-3 in Appendix C, and LFBs for liquefied gases are listed in Exhibit C-2. Both passive and active mitigation measures (discussed in Sections 7.2.2 and 7.2.3) may be taken into account. You do not need to estimate the duration of the release, because this information is not used to estimate distance to the LFL, as discussed in the next chapter.

As for toxic liquids, if the rate of evaporation of the liquid from the pool is greater than the rate of release of the liquid from the container, you should use the liquid release rate, not the pool evaporation rate, as the rate of release to the air. You should expect rapid evaporation rates for liquefied flammable gases from a pool. All of the regulated flammable liquids are volatile, so the evaporation rate from a pool may be expected to be relatively high, particularly without mitigation.

April 15, 1999 9 - 2

## 10 ESTIMATION OF DISTANCE TO THE ENDPOINT FOR

ALTERNATIVE SCENARIOS FOR FLAMMABLE SUBSTANCES

In Chapter 10

� 10.1 Method to estimate the dispersion distance to the LFL for vapor cloud

fires.

� 10.2 Method to estimate the distance to the heat radiation endpoint for a pool fire involving a flammable liquid, based on the pool area and factors provided in the appendix.

� 10.3 Method to estimate the distance to the heat radiation endpoint for a fireball from a BLEVE, using a reference table of distances.

� 10.4 Alternative scenario analysis for vapor cloud explosions, using less conservative assumptions than for worst-case vapor cloud explosions.



### 10.1 Vapor Cloud Fires

The distance to the LFL represents the maximum distance at which the radiant heat effects of a vapor cloud fire might have serious consequences. Exhibit C-2, Appendix C, provides LCL data (in volume percent and milligrams per liter) for listed flammable gases; Exhibit C-3 provides these data for flammable liquids. This guidance provides reference tables for the alternative scenario conditions assumed in this guidance (D stability and wind speed 3.0 meters per second, ground level releases) for estimating the distance to the LCL. Release rate is the primary factor for determining distance to the flammable endpoint. Because the methods used in this guidance assumes that the vapor cloud release is in a steady state and that vapor cloud fires are nearly instantaneous events, release duration is not a critical factor for estimating vapor cloud fire distances. Thus, the reference tables for flammable substances are not broken out sep arately by release durat ion (e.g., 10 minutes, 60 minutes). The development of these tables is discussed further in Appendix D, Section D.4. The reference tables for flammable substances (Reference Tables 26-29 at the end of Chapter 10) are listed in

Exhibit 6.

To use the reference tables of distances to find the distance to the LFL from the release rate, follow these steps:

Find the LFL endpoint for the su bstance in Appe ndix C (Exhibit C-2 for flammable gases or Exhibit C-3 for flammable liquids). �

Determine from Appendix C whether the table for neutrally buoyant or dense gases and vapors is appropriate (Exhibit C-2 for flammable gases or Exhibit C-3 for flammable liquids). A gas that is lighter than air may behave as a dense gas upon release if it is liquefied under pressure, because the released gas may be mixed with liquid droplets, or if it is cold. Consider the state of the released gas when you decide which table is appropriate. �

April 15, 1999Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances

Determine whether the table for rural or urban conditions is appropriate.

-- Use the rural table if your site is in an open area with few obstruct ions.

-- Use the urban table if your site is in an urban or obstructed area. �

Exhibit 6 Reference Tables of Distances for Vapor Cloud Fires of Flammable Substances

Applicable Conditions Reference Table

Number Gas or Vapor Density Topography Release Duration (minutes)

Neutrally buoyant Rural 10 - 60 26

Urban 10 - 60 27

Dense Rural 10 - 60 28

Urban 10 - 60 29

Neutrally Buoyant Gases or Vapors

If Exhibit C-2 or C-3 indicates the gas or vapor should be considered neutrally buoyant, and other factors would not cause the gas or vapor to behave as a dense gas, divide the estimated release rate (pounds per minute) by the LFL endpoint (milligrams per liter). �

Find the range of release rate/LFL values that includes your calculated release rate/LFL in the first column of the appropriate table (Reference Table 26 or 27), then find the corresponding distance to the right. �

Dense Gases or Vapors

If Exhibit C-2 or C-3 or consideration of other relevant factors indicates the su bstance should be considered a dense gas or vapor (heavier than air), find the distance in the appropriate table (Reference Table 28 or 29) as follows: �

-- Find the LFL closest to that of the su bstance by rea ding across the top of the table. If the LFL of the substance is halfway between two values on the table, c hoose the value on the table that is smaller (to the left). Otherwise, choose the closest value to the right or the left.

-- Find the release rate closest to the release rate estimated for the su bstance at the left of the table. If the calculated release rate is halfway between two values on the

April 15, 1999 10 - 2Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances

table, choose the release rate that is larger (farther down on the table). Otherwise, choose the closest value (up or down on the table).

-- Read across from the release rate and down from the LFL to find the distance corresponding to the LFL and release rate for your su bstance.

Example 27. Flammable Gas Release (Ethylene)

In Example 26, you estimated a release rate for ethylene from a hole in a tank of 3,900 p ounds per minute. You want to estimate the distance to the LFL for a vapor cloud fire resulting from this release.

From Exhibit C-2, Appendix C, the LFL for ethylene is 31 mg/L, and the appropriate table for distance estimation is a neutrally buoyant gas table for flammable substances. Your site is in a rural area, so you would

use Reference Table 26.

To use the neutrally buoyant gas tables, you need to calculate release rate/endpoint. In this case, release rate/LFL = 3,900/31 or 126. On Reference Table 26, 126 falls in the range of release rate/LFL values corresponding to 0.2 miles.

April 15, 1999 10 - 3Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances

Example 28. Vapor Cloud Fire from Evaporating Pool of Flammable Liquid

You have a tank containing 20,000 p ounds of ethyl ether. A likely scenario for a release might be shearing of a pipe from the tank, with the released liquid forming a pool. You want to estimate the consequences of a vapor cloud fire that might result from evaporation of the pool and ignition of the vapor.

You first need to estimate the rate of release of the liquid from the tank. You can do this using Equation 7-4, Section 7.2.1. For this calculation, you need the area of the hole that would result from shearing the pipe (HA), the height of the liquid in the tank above the hole (LH), and the liquid leak factor (LLF) for ethyl ether, from Exhibit C-3 in Appendix C. The pipe diameter is 2 inches, so the cross sectional area of the hole would be 3.1 square inches. You estimate that the pipe is 2 feet, or 24 inches, below the level of the liquid when the tank is full. The square root of LH (24 inches) is 4.9. LLF for ethyl ether is 34. From Equation 7-4, the rate of release of the liquid from the hole is calculated as:

QR L = 3.1 × 4.9 × 34 = 520 p ounds per minute

You estimate that the release of the liquid could be stopped in about 10 minutes. In 10 minutes, 10 × 520, or 5,200 p ounds, would be released.

The liquid would be released into an area without dikes. To estimate the evaporation rate from the pool formed by the released liquid, you use Equation 7-8 from Section 7.2.3. To carry out the calculation, you need the Liquid Factor Ambient (LFA) and the Density Factor (DF) for ethyl ether. From Exhibit C-3, Appendix C, LFA for ethyl ether is 0.11 and DF is 0.69. The release rate to air is:

QR = 5,200 × 2.4 × 0.11 × 0.69 = 950 p ounds per minute

The evaporation rate from the pool is greater than the estimated liquid release rate; therefore, you use the liquid release rate of 520 p ounds per minute as the release rate to air. To estimate the maximum distance at which people in the area of the vapor cloud could suffer serious injury, estimate the distance to the lower flammability limit (LFL) (in milligrams per liter) for ethyl ether, from the appropriate reference table. From Exhibit C-3, Appendix C, LFL for ethyl ether is 57 mg/L, and the appropriate reference table is a dense gas table. Your site is in a rural area with few obstructions, so you use Reference Table 28.

From Reference Table 28, the closest LFL is 60 mg/L. The lowest release rate on the table is 1,500 p ounds per minute, which is higher than the evaporation rate estimated for the pool of ethyl ether. For a release rate less than 1,500 p ounds per minute, the distance to the LFL is less than 0.1 miles.

April 15, 1999 10 - 4Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances



### 10.2 Pool Fires

Pool fires may be considered as potential alternative scenarios for flammable liquids, including gases liquefied by refrigeration alone. You may find, however, that other scenarios will give a greater distance to the endpoint and, therefore, may be more appropriate as alternative scenarios. A "Pool Fire Factor" (PFF) has been derived for each of the regulated flammable liquids and most of the flammable gases to aid in the consequence analysis. The derivation of these factors is discussed in Appendix D, Section D.9. The PFF, listed in Appendix C, Exhibit C-2 for flammable gases and C-3 for flammable liquids, may be used to estimate a distance from the center of a pool fire where people could potentially r eceive second degree burns from a 40-second exposure. The heat radiation endpoint for this analysis is 5 kilowa tts per square meter

2 o o (kW/m ). Ambient temperature is assumed to be 25 C (77 F) for calculation of the PFF for flammable liquids.

To estimate a distance using the PFF, you first need to estimate the size of the p ool, in square feet, that might be formed by the release of a flammable su bstance. You may use the methods described above for toxic liquids to estimate pool size. Density factors (DF) for the estimation of pool size in undiked areas may be found for flammable gases and flammable liquids in Exhibits C-2 and C-3 of Appendix C. For flammable gases, the DF is based on the density at the boiling point. You may want to consider whether the released substance may evaporate too quickly to form a p ool of the maximum size, particularly for liquefied gases.

Distances may be estimated from the PFF and the p ool area as follows:



### d � PFF × A (10-1)

where: d = Distance (feet)

PFF = Pool Fire Factor (listed for each flammable su bstance in Appe ndix C, Exhibits C-2 and C-3)

A = Pool area (square feet)

April 15, 1999 10 - 5Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances

Example 29. Pool Fire of Flammable Liquid

For a tank containing 20,000 p ounds of ethyl ether, you want to estimate the consequences of a pool fire. You estimate that 15,000 p ounds would be released into an area without dikes, forming a pool. Assuming the liquid spreads to a depth of 1 centimeter (0.39 inches), you estimate the area of the pool formed from Equation 3-6, Section 3.2.3. For this calculation, you need the density factor (DF) for ethyl ether; from Exhibit C-3, Appendix C, DF for ethyl ether is 0.69. From Equation 3-6, the area of the pool is:

A = 15,000 × 0.69 = 10,400 square feet

You can use Equation 10-1 to estimate the distance from the center of the burning pool where the heat radiation

level would reach 5 kW/m . 2 For the calculation, you need the square root of the pool area (A) and the pool fire factor (PFF) for ethyl ether. The square root of A, 10,400 square feet, is 102 feet. From Exhibit C-3,

2 Appendix C, PFF for ethyl ether is 4.3. From Equation 10-1, the distance (d) to 5 kW/m is:

d = 4.3 × 102 = 440 feet (about 0.08 miles)

If you have a gas that is liquefied under pressure or under a combination of pressure and refrigeration, a pool fire is probably not an appropriate alternative scenario. A fire or explosion involving the flammable gas that is released to the air by a sudden release of pressure is likely to have the potential for serious effects at a greater distance than a pool fire (e.g., see the methods for analysis of BLEVEs and vapor cloud explosions in Sections 10.3 and 10.4 below, or see Appendix A for references that provide more information on consequence analysis for fires and explosions).



### 10.3 BLEVEs

If a fireball from a BLEVE is a potential release scenario at your site, you may use Reference Table 30 to estimate the distance to a potentially harmful radiant heat level. The table shows distances for a range of quantities to the radiant heat level that potentially could cause second degree burns to a person exposed for the duration of the fire. The quantity you use should be the total quantity in a tank that might be involved in a BLEVE. The equations used to derive this table of distances are presented in Appendix D, Section D.10. If you prefer, you may use the equations to estimate a distance for BLEVEs, or you may use a different

calculation method or model.



### 10.4 Vapor Cloud Explosion

If you have the potential at your site for the rapid release of a large quantity of a flammable vapor, particularly into a congested area, a vapor cloud explosion may be an appropriate alternative release scenario. For the consequence analysis, you may use the same methods as for the worst case to estimate consequence distances to an overpressure endpoint of 1 psi (see Section 5.1 and the equation in Appendix C). Instead of assuming the total quantity of flammable su bstance released is in the vapor c loud, you may estimate a smaller

April 15, 1999 10 - 6Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances

quantity in the cloud. You could base your estimate of the quantity in the cloud on the release rate estimated as described above for gases and liquids multiplied by the time required to stop the release.

To estimate the quantity in the cloud for a gas liquefied under pressure (not refrigerated), you may use the equation below. This equation incorporates a "flash fract ion factor" (FFF), listed in Appe ndix C, Exhibit C-2 for regulated flammable gases, to estimate the quantity that could be i mmediately flashed into vapor upon release. A factor of two is included to estimate the quantity that might be c arried a long as spray or aerosol. See Appendix D, Section D.11 for the derivation of this equation. The equation is:



### QF FFF × QS ×2 (10-2) �

where: QF = Quantity flashed into vapor plus aerosol (pounds) (cannot be larger than QS)

FFF = Flash fract ion factor (unitless) (listed in Appendix C, Exhibit C-2) (must be less than 1) QS = Quantity spilled (pounds) 2 = Factor to account for spray and aerosol

o o For derivation of the FFF, the temperature of the stored gas was assumed to be 25 C (77 F) (except as noted in Exhibit C-2). You may estimate the flash fract ion under other conditions using the equation presented in Appendix D, Section D.11.

You may estimate the distance to 1 psi for a vapor cloud explosion from the quantity in the cloud using Reference Table 13 (at the end of the worst-case analysis discussion) or from Equation C-1 in Appendix C. For the alternative scenario analysis, you may use a yield factor of 3 percent, instead of the yield factor of 10 percent used in the worst-case analysis. As discussed in Appendix D, Section D.11, the yield factor of 3 percent is representative of more likely events, based on data from past vapor cloud explosions. If you use the equation in Appendix C, use 0.03 instead of 0.1 in the calculation. If you use Reference Table 13, you can incorporate the lower yield factor by multiplying the distance you read from Reference Table 13 by 0.67.

April 15, 1999 10 - 7Chapter 10 Estimation of Distance to the Endpoint for Alternative Scenarios for Flammable Substances

Example 30. Vapor Cloud Explosion (Propane)

You have a tank containing 50,000 p ounds of propane liquefied under pressure at ambient temperature. You want to estimate the consequence distance for a vapor cloud explosion resulting from rupture of the tank.

You use Equation 10-2 to estimate the quantity that might be released to form a cloud. You base the calculation on the entire contents of the tank (QS = 50,000 p ounds). From Exhibit C-2 of Appendix C, the Flash Fraction Factor (FFF) for propane is 0.38. From Equation 10-2, the quantity flashed into vapor, plus the quantity that might be carried along as aerosol, (QF) is:

QF = 0.38 × 50,000 × 2 = 38,000 p ounds

You assume 38,000 p ounds of propane is in the flammable part of the vapor cloud. This quantity falls between 20,000 p ounds and 50, 000 p ounds in Reference Table 13; 50, 000 p ounds is the quantity closest to your quantity. From the table, the distance to 1 psi overpressure is 0.3 mile for 50, 000 p ounds of propane for a 10 percent yield factor. To change the yield factor to 3 percent, you multiply this distance by 0.67; then the

distance becomes 0.2 mile.

April 15, 1999 10 - 8Reference Table 14 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 10-Minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 64 0.1

64 - 510 0.2

510 - 1,300 0.3

1,300 - 2,300 0.4

2,300 - 4,100 0.6

4,100 - 6,300 0.8

6,300 - 8,800 1.0

8,800 - 12,000 1.2

12,000 - 16,000 1.4

16,000 - 19,000 1.6

19,000 - 22,000 1.8

22,000 - 26,000 2.0

26,000 - 30,000 2.2

30,000 - 36,000 2.4

36,000 - 42,000 2.6

42,000 - 47,000 2.8

47,000 - 54,000 3.0

54,000 - 60,000 3.2

60,000 - 70,000 3.4

70,000 - 78,000 3.6

78,000 - 87,000 3.8

87,000 - 97,000 4.0

97,000 - 110,000 4.2

110,000 - 120,000 4.4

120,000 - 130,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

130,000 - 140,000 4.8

140,000 - 160,000 5.0

160,000 - 180,000 5.2

180,000 - 190,000 5.4

190,000 - 210,000 5.6

210,000 - 220,000 5.8

220,000 - 240,000 6.0

240,000 - 261,000 6.2

261,000 - 325,000 6.8

325,000 - 397,000 7.5

397,000 - 477,000 8.1

477,000 - 566,000 8.7

566,000 - 663,000 9.3

663,000 - 769,000 9.9

769,000 - 1,010,000 11

1,010,000 - 1,280,000 12

1,280,000 - 1,600,000 14

1,600,000 - 1,950,000 15

1,950,000 - 2,340,000 16

2,340,000 - 2,770,000 17

2,770,000 - 3,240,000 19

3,240,000 - 4,590,000 22

4,590,000 - 6,190,000 25

>6,190,000 >25*

*Report distance as 25 miles

April 15, 1999 10 - 9Reference Table 15 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 60-Minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 79 0.1

79 - 630 0.2

630 - 1,600 0.3

1,600 - 2,800 0.4

2,800 - 5,200 0.6

5,200 - 7,900 0.8

7,900 - 11,000 1.0

11,000 - 14,000 1.2

14,000 - 19,000 1.4

19,000 - 23,000 1.6

23,000 - 27,000 1.8

27,000 - 32,000 2.0

32,000 - 36,000 2.2

36,000 - 42,000 2.4

42,000 - 47,000 2.6

47,000 - 52,000 2.8

52,000 - 57,000 3.0

57,000 - 61,000 3.2

61,000 - 68,000 3.4

68,000 - 73,000 3.6

73,000 - 79,000 3.8

79,000 - 84,000 4.0

84,000 - 91,000 4.2

91,000 - 97,000 4.4

97,000 - 100,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

100,000 - 108,000 4.8

108,000 - 113,000 5.0

113,000 - 120,000 5.2

120,000 - 126,000 5.4

126,000 - 132,000 5.6

132,000 - 140,000 5.8

140,000 - 150,000 6.0

150,000 - 151,000 6.2

151,000 - 171,000 6.8

171,000 - 191,000 7.5

191,000 - 212,000 8.1

212,000 - 233,000 8.7

233,000 - 256,000 9.3

256,000 - 280,000 9.9

280,000 - 332,000 11

332,000 - 390,000 12

390,000 - 456,000 14

456,000 - 529,000 15

529,000 - 610,000 16

610,000 - 699,000 17

699,000 - 796,000 19

796,000 - 1,080,000 22

1,080,000 - 1,410,000 25

>1,410,000 >25*

*Report distance as 25 miles

April 15, 1999 10 - 10Reference Table 16 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 10-Minute Release, Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint (miles)

0 - 160 0.1

160 - 1,400 0.2

1,400 - 3,600 0.3

3,600 - 6,900 0.4

6,900 - 13,000 0.6

13,000 - 22,000 0.8

22,000 - 31,000 1.0

31,000 - 42,000 1.2

42,000 - 59,000 1.4

59,000 - 73,000 1.6

73,000 - 88,000 1.8

88,000 - 100,000 2.0

100,000 - 120,000 2.2

120,000 - 150,000 2.4

150,000 - 170,000 2.6

170,000 - 200,000 2.8

200,000 - 230,000 3.0

230,000 - 260,000 3.2

260,000 - 310,000 3.4

310,000 - 340,000 3.6

340,000 - 390,000 3.8

390,000 - 430,000 4.0

430,000 - 490,000 4.2

490,000 - 540,000 4.4

540,000 - 600,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

600,000 - 660,000 4.8

660,000 - 720,000 5.0

720,000 - 810,000 5.2

810,000 - 880,000 5.4

880,000 - 950,000 5.6

950,000 - 1,000,000 5.8

1,000,000 - 1,100,000 6.0

1,100,000 - 1,220,000 6.2

1,220,000 - 1,530,000 6.8

1,530,000 - 1,880,000 7.5

1,880,000 - 2,280,000 8.1

2,280,000 - 2,710,000 8.7

2,710,000 - 3,200,000 9.3

3,200,000 - 3,730,000 9.9

3,730,000 - 4,920,000 11

4,920,000 - 6,310,000 12

6,310,000 - 7,890,000 14

7,890,000 - 9,660,000 15

9,660,000 - 11,600,000 16

11,600,000 - 13,800,000 17

13,800,000 - 16,200,000 19

16,200,000 - 23,100,000 22

23,100,000 - 31,300,000 25

>31,300,000 >25*

*Report distance as 25 miles

April 15, 1999 10 - 11Reference Table 17 Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divi ded by Endpoint 60-Minute Release, Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 200 0.1

200 - 1,700 0.2

1,700 - 4,500 0.3

4,500 - 8,600 0.4

8,600 - 17,000 0.6

17,000 - 27,000 0.8

27,000 - 39,000 1.0

39,000 - 53,000 1.2

53,000 - 73,000 1.4

73,000 - 90,000 1.6

90,000 - 110,000 1.8

110,000 - 130,000 2.0

130,000 - 150,000 2.2

150,000 - 170,000 2.4

170,000 - 200,000 2.6

200,000 - 220,000 2.8

220,000 - 240,000 3.0

240,000 - 270,000 3.2

270,000 - 300,000 3.4

300,000 - 320,000 3.6

320,000 - 350,000 3.8

350,000 - 370,000 4.0

370,000 - 410,000 4.2

410,000 - 430,000 4.4

430,000 - 460,000 4.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

460,000 - 490,000 4.8

490,000 - 520,000 5.0

520,000 - 550,000 5.2

550,000 - 580,000 5.4

580,000 - 610,000 5.6

610,000 - 640,000 5.8

640,000 - 680,000 6.0

680,000 - 705,000 6.2

705,000 - 804,000 6.8

804,000 - 905,000 7.5

905,000 - 1,010,000 8.1

1,010,000 - 1,120,000 8.7

1,120,000 - 1,230,000 9.3

1,230,000 - 1,350,000 9.9

1,350,000 - 1,620,000 11

1,620,000 - 1,920,000 12

1,920,000 - 2,250,000 14

2,250,000 - 2,620,000 15

2,620,000 - 3,030,000 16

3,030,000 - 3,490,000 17

3,490,000 - 3,980,000 19

3,980,000 - 5,410,000 22

5,410,000 - 7,120,000 25

>7,120,000 >25*

*Report distance as 25 miles

April 15, 1999 10 - 12Reference Table 18Dense Gas Distances to Toxic Endpoint10-minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)10.60.40.40.20.20.10.10.1<0.1<0.1######20.90.60.50.40.30.20.20.10.10.1<0.1<0.1####51.41.10.90.60.40.40.30.20.20.10.10.1<0.1###102.01.51.20.90.60.50.40.40.20.20.10.10.1<0.1<0.1#303.72.72.21.51.10.90.70.70.50.30.30.20.20.10.1<0.1505.03.73.02.11.91.21.00.90.60.40.40.30.20.20.10.11007.45.34.33.02.31.71.41.20.90.60.60.40.40.20.20.11508.76.85.53.82.82.31.91.61.10.80.70.60.50.30.20.2250128.77.45.03.73.02.42.11.41.10.90.70.50.40.30.25001713117.45.34.53.63.02.11.61.31.10.90.60.40.37502216139.36.85.64.53.82.71.91.61.31.10.70.50.41,000>251916118.16.85.24.53.12.32.21.51.30.80.60.41,500*2319139.98.16.85.63.92.92.41.91.61.00.70.62,000*>252215129.37.46.84.53.42.72.21.91.20.80.62,500**251713118.77.45.23.83.22.52.11.30.90.73,000**>251914129.38.15.74.23.52.82.41.41.00.84,000***221714119.36.84.94.13.32.81.71.10.95,000***>25191612117.45.64.73.73.12.11.31.17,500 241916139.36.85.84.74.02.41.61.310,000** **>25221816118.16.85.34.62.81.91.515,000*****>252219139.98.16.85.73.52.41.920,000******>252216119.37.46.84.02.82.250,000*******>2524181512106.54.53.675,000********>25221815137.85.44.4100,000*********>252117148.96.35.0150,000**********>252017117.46.0200,000***********2319128.56.8*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)10 - 13Reference Table 19Dense Gas Distances to Toxic Endpoint60-minute Release, Rural Conditions, D Stability, WindSpeed 3.0 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)10.50.40.30.20.20.10.10.1<0.1#######20.80.60.50.30.20.20.20.10.1<0.1<0.1<0.1####51.61.00.80.50.40.30.20.20.20.10.10.1<0.1###102.01.41.20.80.60.50.40.30.20.20.10.10.1<0.1<0.1#304.02.82.21.51.10.90.70.60.40.30.20.20.20.10.1<0.1505.53.93.12.11.51.21.00.80.60.40.30.30.20.10.10.11008.76.14.83.22.21.81.41.20.80.60.50.40.30.20.10.1150128.16.24.12.92.31.81.61.10.70.60.50.40.30.20.125017118.75.64.03.22.52.11.41.10.90.70.60.40.20.2500>2519149.36.25.03.93.32.21.61.31.00.90.50.40.3750*2519128.76.85.14.22.82.01.61.31.10.60.40.41,000*>252415118.16.15.23.42.41.91.51.30.70.50.41,500**>252014118.16.84.33.02.51.91.71.00.70.52,000***2417139.98.15.23.72.92.31.91.20.70.62,500***>251915129.36.04.33.42.72.21.30.90.73,000 221713116.84.83.83.02.51.51.00.84,000** **>252116148.75.84.73.63.01.71.20.95,000*****2519169.96.85.34.13.52.01.41.17,500*****>252520139.36.85.44.52.61.71.410,000******>252516118.76.85.43.12.11.615,000*******>252114118.77.44.02.62.120,000********251714118.74.83.12.550,000********>25>252519168.85.64.375,000**********>252520117.35.6100,000***********>2524149.46.8150,000************>2517118.7200,000*************201310*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)10 - 14Reference Table 20Dense Gas Distances to Toxic Endpoint10-minute Release, Urban Conditions, D Stability, WindSpeed 3.0 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)10.50.30.20.20.10.10.10.1<0.1#######20.70.50.40.30.20.20.10.10.1<0.1<0.1#####51.10.80.60.50.30.30.20.20.10.10.1<0.1<0.1###102.11.21.00.70.50.40.30.30.20.10.10.10.1<0.1##303.02.21.91.20.90.80.60.60.40.30.20.20.10.1<0.1#504.13.02.51.61.21.00.80.70.50.30.30.20.20.10.1<0.11005.84.33.52.71.81.41.21.00.70.60.40.40.30.20.10.11507.45.54.53.12.21.91.41.20.90.70.60.40.40.20.20.12509.97.45.84.13.02.52.01.71.10.90.70.60.50.30.20.150014118.75.94.33.62.92.51.71.21.00.80.70.40.30.27501713117.45.54.53.63.12.11.61.21.00.90.50.40.31,0002015128.76.25.34.33.52.51.81.51.21.00.60.40.31,500>251916118.16.25.24.53.02.21.81.51.20.70.50.42,000*2218129.37.46.25.23.72.72.21.71.40.90.60.52,500*242014118.76.86.03.83.02.21.91.71.00.70.63,000*>252216119.37.46.84.53.32.72.11.91.10.70.64,000**>251814118.77.45.34.03.22.62.11.20.90.75,000***2015129.98.75.84.43.62.92.41.40.90.77,500***>25191612117.45.54.53.63.01.81.20.910,000 221814128.76.25.24.23.62.11.41.115,000** **>25221816118.16.85.24.42.61.71.320,000*****>252018129.37.46.05.23.02.01.650,000******>25>252015129.78.35.03.32.675,000********25181512106.14.13.1100,000********>25211714127.04.73.7150,000*********>252117148.55.74.5200,000**********2419169.76.55.1*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)10 - 15Reference Table 21Dense Gas Distances to Toxic Endpoint60-minute Release, Urban Conditions, D Stability, WindSpeed 3.0 Meters per SecondReleaseRateToxic Endpoint (mg/L)0.00040.00070.0010.0020.00350.0050.00750.010.020.0350.050.0750.10.250.50.75(lbs/min)Distance (Miles)10.40.30.20.20.10.10.1<0.1########20.70.50.40.20.20.20.10.1<0.1<0.1######51.10.80.70.40.30.20.20.20.10.1<0.1<0.1<0.1###101.71.21.00.70.50.40.30.30.20.10.10.10.1<0.1##303.32.41.91.30.90.70.60.50.30.20.20.20.10.1<0.1#504.73.32.61.71.21.00.80.70.40.30.30.20.20.10.1<0.11007.45.24.12.71.91.51.21.00.70.50.40.30.30.20.10.11509.96.85.33.42.41.91.51.30.90.60.50.40.30.20.10.1250149.37.44.73.42.72.11.71.10.80.70.50.40.30.20.15002216127.45.24.23.22.71.71.21.00.80.70.40.20.2750>2520169.96.85.44.23.52.21.61.31.00.90.50.30.31,000*2419128.16.85.04.22.71.81.61.21.00.60.40.31,500*>25>2516118.76.85.53.51.92.01.61.30.70.50.42,000***1914118.16.84.23.02.21.91.60.90.60.42,500***2316129.37.44.93.42.72.11.71.00.60.53,000***>251814118.75.53.83.02.42.01.10.70.64,000 221713116.84.73.12.82.41.30.90.75,000** **>252016128.15.34.33.32.71.51.00.77,500*****252017116.85.64.33.52.01.20.910,000*****>252420138.76.85.24.32.41.51.115,000******>25>2517118.76.85.63.01.91.520,000********2014118.16.83.62.31.750,000********>25>252015136.64.03.175,000**********>2520168.75.33.9100,000***********2420106.34.7150,000***********>25>25148.26.1200,000*************169.97.3*> 25 miles (report distance as 25 miles)# <0.1 mile (report distance as 0.1 mile)10 - 16Reference Table 22 Distances to Toxic Endpoint for Anhydrous Ammonia Liquefied Under Pressure D Stability, Wind Speed 3.0 Meters per Second

Release Rate

(lbs/min) Distance to Endpoint (miles)

Rural Urban

<10 <0.1*

<0.1* 10 0.1

15 0.1

20 0.1

30 0.1

40 0.1

50 0.1

60 0.2 0.1

70 0.2 0.1

80 0.2 0.1

90 0.2 0.1

100 0.2 0.1

150 0.2 0.1

200 0.3 0.1

250 0.3 0.1

300 0.3 0.1

400 0.4 0.2

500 0.4 0.2

600 0.5 0.2

700 0.5 0.2

750 0.5 0.2

800 0.5 0.2 Release Rate (lbs/min) Distance to Endpoint (miles)

Rural Urban

900 0.6 0.2

1,000 0.6 0.2

1,500 0.7 0.3

2,000 0.8 0.3

2,500 0.9 0.3

3,000 1.0 0.4

4,000 1.2 0.4

5,000 1.3 0.5

7,500 1.6 0.5

10,000 1.8 0.6

15,000 2.2 0.7

20,000 2.5 0.8

25,000 2.8 0.9

30,000 3.1 1.0

40,000 3.5 1.1

50,000 3.9 1.2

75,000 4.8 1.4

100,000 5.4 1.6

150,000 6.6 1.9

200,000 7.6 2.1

250,000 8.4 2.3

* Report distance as 0.1 mile

April 15, 1999 10 - 17Reference Table 23 Distances to Toxic Endpoint for Non-liquefied Ammonia, Ammonia Liquefied by Refrigeration, or Aqueous Ammonia D Stability, Wind Speed 3.0 Meters per Second

Release Rate

(lbs/min) Distance to Endpoint (miles)

Rural Urban

<8 <0.1*

<0.1* 8 0.1

10 0.1

15 0.1

20 0.1

30 0.1

40 0.1

50 0.2 0.1

60 0.2 0.1

70 0.2 0.1

80 0.2 0.1

90 0.2 0.1

100 0.2 0.1

150 0.3 0.1

200 0.3 0.1

250 0.4 0.2

300 0.4 0.2

400 0.4 0.2

500 0.5 0.2

600 0.6 0.2

700 0.6 0.2

750 0.6 0.2 Release Rate (lbs/min) Distance to Endpoint (miles)

Rural Urban

800 0.7 0.2

900 0.7 0.3

1,000 0.8 0.3

1,500 1.0 0.4

2,000 1.2 0.4

2,500 1.2 0.4

3,000 1.5 0.5

4,000 1.8 0.6

5,000 2.0 0.7

7,500 2.2 0.7

10,000 2.5 0.8

15,000 3.1 1.0

20,000 3.6 1.2

25,000 4.1 1.3

30,000 4.4 1.4

40,000 5.1 1.6

50,000 5.8 1.8

75,000 7.1 2.2

100,000 8.2 2.5

150,000 10 3.1

200,000 12 3.5

* Report distance as 0.1 mile

April 15, 1999 10 - 18Reference Table 24 Distances to Toxic Endpoint for Chlorine D Stability, Wind Speed 3.0 Meters per Second

Release Rate

(lbs/min) Distance to Endpoint (miles)

Rural Urban

1 <0.1*

<0.1*
2 0.1

5 0.1

10 0.2 0.1

15 0.2 0.1

20 0.2 0.1

30 0.3 0.1

40 0.3 0.1

50 0.3 0.1

60 0.4 0.2

70 0.4 0.2

80 0.4 0.2

90 0.4 0.2

100 0.5 0.2

150 0.6 0.2

200 0.6 0.3

250 0.7 0.3

300 0.8 0.3

400 0.8 0.4

500 1.0 0.4

600 1.0 0.4

700 1.1 0.4 Release Rate (lbs/min) Distance to Endpoint (miles)

Rural Urban

750 1.2 0.4

800 1.2 0.5

900 1.2 0.5

1,000 1.3 0.5

1,500 1.6 0.6

2,000 1.8 0.6

2,500 2.0 0.7

3,000 2.2 0.8

4,000 2.5 0.8

5,000 2.8 0.9

7,500 3.4 1.2

10,000 3.9 1.3

15,000 4.6 1.6

20,000 5.3 1.8

25,000 5.9 2.0

30,000 6.4 2.1

40,000 7.3 2.4

50,000 8.1 2.7

75,000 9.8 3.2

100,000 11 3.6

150,000 13 4.2

200,000 15 4.8

* Report distance as 0.1 mile

April 15, 1999 10 - 19Reference Table 25 Distances to Toxic Endpoint for Sulfur Dioxide D Stability, Wind Speed 3.0 Meters per Second

Release Rate

(lbs/min) Distance to Endpoint (miles)

Rural Urban

1 <0.1*

<0.1*
2 0.1

5 0.1

10 0.2 0.1

15 0.2 0.1

20 0.2 0.1

30 0.2 0.1

40 0.3 0.1

50 0.3 0.1

60 0.4 0.2

70 0.4 0.2

80 0.4 0.2

90 0.4 0.2

100 0.5 0.2

150 0.6 0.2

200 0.6 0.2

250 0.7 0.3

300 0.8 0.3

400 0.9 0.4

500 1.0 0.4

600 1.1 0.4

700 1.2 0.4 Release Rate (lbs/min) Distance to Endpoint (miles)

Rural Urban

750 1.3 0.5

800 1.3 0.5

900 1.4 0.5

1,000 1.5 0.5

1,500 1.9 0.6

2,000 2.2 0.7

2,500 2.3 0.8

3,000 2.7 0.8

4,000 3.1 1.0

5,000 3.3 1.1

7,500 4.0 1.3

10,000 4.6 1.4

15,000 5.6 1.7

20,000 6.5 1.9

25,000 7.3 2.1

30,000 8.0 2.3

40,000 9.2 2.6

50,000 10 2.9

75,000 13 3.5

100,000 14 4.0

150,000 18 4.7

200,000 20 5.4

* Report distance as 0.1 mile

April 15, 1999 10 - 20Reference Table 26 Neutrally Buoyant Plume Distances to Lower Flammab ility Limit (LFL) For Release Rate Divided by LFL Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 28 0.1

28 - 40 0.1

40 - 60 0.1

60 - 220 0.2

220 - 530 0.3

530 - 860 0.4

860 - 1,300 0.5

1,300 - 1,700 0.6

1,700 - 2,200 0.7

2,200 - 2,700 0.8 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

2,700 - 3,300 0.9

3,300 - 3,900 1.0

3,900 - 4,500 1.1

4,500 - 5,200 1.2

5,200 - 5,800 1.3

5,800 - 6,800 1.4

6,800 - 8,200 1.6

8,200 - 9,700 1.8

9,700 - 11,000 2.0

11,000 - 13,000 2.2

Reference Table 27 Neutrally Buoyant Plume Distances to Lower Flammab ility Limit (LFL) For Release Rate Divided by LFL Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

0 - 68 0.1

68 - 100 0.1

100 - 150 0.1

150 - 710 0.2

710 - 1,500 0.3

1,500 - 2,600 0.4

2,600 - 4,000 0.5

4,000 - 5,500 0.6 Release Rate/Endpoint [(lbs/min)/(mg/L)] Distance to Endpoint

(miles)

5,500 - 7,300 0.7

7,300 - 9,200 0.8

9,200 - 11,000 0.9

11,000 - 14,000 1.0

14,000 - 18,000 1.2

18,000 - 26,000 1.4

26,000 - 31,000 1.6

31,000 - 38,000 1.8

April 15, 1999 10 - 21Reference Table 28Dense Gas Distances to Lower Flammability LimitRural Conditions, D Stability, WindSpeed 3.0 Meters per SecondReleaseRate(lbs/min)Lower Flammability Limit (mg/L)2730354045506070100>100Distance (Miles)<1,500##########1,500<0.1<0.1########2,0000.10.1<0.1#######2,5000.10.10.1<0.1######3,0000.10.10.10.1<0.1<0.1####4,0000.10.10.10.10.10.1<0.1###5,0000.10.10.10.10.10.10.1<0.1##7,5000.20.10.10.10.10.10.10.1<0.1#10,0000.20.20.10.10.10.10.10.10.1<0.1# < 0.1 mile (report distance as 0.1 mile)April 15, 199910 - 22Reference Table 29 Dense Gas Distances to Lower Flammability Limit Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release

Rate (lbs/min) Lower Flammability Limit (mg/L)

27 30 35 40 >40

Distance (Miles)

<5,000 # # # # #

5,000 <0.1 <0.1 # # #

7,500 0.1 0.1 <0.1 # #

10,000 0.1 0.1 0.1 <0.1 #

# < 0.1 mile (report distance as 0.1 mile)

April 15, 1999 10 - 23Reference Table 30Distance to Radiant Heat Dose at Potential Second Degree Burn Threshold Assuming Exposure for Duration of Fireball from BLEVE(Dose = [5 kW/m ]2 4/3x Exposure Time)Quantityin Fireball (pounds)1,0005,00010,00020,00030,00050,00075,000100,000200,000300,000500,000Duration of Fireball (seconds)3.55.97.59.410.812.714.815.517.418.720.3CAS No.Chemical NameDistance (miles) at which Exposure for Duration of Fireball MayCause Second Degree Burns75-07-0Acetaldehyde0.040.080.10.10.20.20.30.30.40.50.674-86-2Acetylene0.050.10.10.20.20.30.40.40.50.60.8598-73-2Bromotrifluoroethylene0.010.020.030.040.050.060.070.080.10.10.2106-99-01,3-Butadiene0.050.10.10.20.20.30.40.40.50.60.8106-97-8Butane0.050.10.10.20.20.30.40.40.50.60.8106-98-91-Butene0.050.10.10.20.20.30.40.40.50.60.8107-01-72-Butene0.050.10.10.20.20.30.40.40.50.60.825167-67-3Butene0.050.10.10.20.20.30.40.40.50.60.8590-18-12-Butene-cis0.050.10.10.20.20.30.40.40.50.60.8624-64-62-Butene-trans0.050.10.10.20.20.30.40.40.50.60.8463-58-1Carbon oxysulfide0.020.050.060.090.10.10.20.20.20.30.37791-21-1Chlorine monoxide0.010.020.020.030.030.040.050.060.080.090.1557-98-22-Chloropropylene0.030.070.10.10.20.20.20.30.40.40.5590-21-61-Chloropropylene0.030.070.10.10.20.20.20.30.40.40.5460-19-5Cyanogen0.030.070.10.10.20.20.20.30.40.40.575-19-4Cyclopropane0.050.10.10.20.20.30.40.40.50.60.84109-96-0Dichlorosilane0.020.040.060.080.10.10.20.20.20.30.375-37-6Difluoroethane0.020.050.070.10.10.10.20.20.30.30.4124-40-3Dimethylamine0.040.090.10.20.20.30.30.40.50.50.7463-82-12,2-Dimethylpropane0.050.10.10.20.20.30.40.40.50.60.874-84-0Ethane0.050.10.10.20.20.30.40.40.50.60.8107-00-6Ethyl acetylene0.050.10.10.20.20.30.40.40.50.60.8April 15, 199910 - 24Reference Table 30 (continued)Quantityin Fireball (pounds)1,0005,00010,00020,00030,00050,00075,000100,000200,000300,000500,000Duration of Fireball (seconds)3.55.97.59.410.812.714.815.517.418.720.3CAS No.Chemical NameDistance (miles) at which Exposure for Duration of Fireball MayCause Second Degree Burns75-04-7Ethylamine0.040.090.10.20.20.30.30.40.50.50.775-00-3Ethyl chloride0.030.070.090.10.20.20.20.30.30.40.574-85-1Ethylene0.050.10.10.20.20.30.40.40.50.60.860-29-7Ethyl ether0.040.090.10.20.20.20.30.30.50.50.775-08-1Ethyl mercaptan0.040.080.10.20.20.20.30.30.40.50.6109-95-5Ethyl nitrite0.030.060.090.10.10.20.20.30.30.40.51333-74-0Hydrogen0.080.20.20.30.40.50.60.60.91.01.275-28-5Isobutane0.050.10.10.20.20.30.40.40.50.60.878-78-4Isopentane0.050.10.10.20.20.30.40.40.50.60.878-79-5Isoprene0.050.10.10.20.20.30.40.40.50.60.775-31-0Isopropylamine0.040.090.10.20.20.30.30.40.50.60.775-29-6Isopropyl chloride0.040.070.10.10.20.20.30.30.40.40.574-82-8Methane0.050.10.10.20.20.30.40.40.60.60.874-89-5Methylamine0.040.080.10.20.20.20.30.30.40.50.6563-45-13-Methyl-1-butene0.050.10.10.20.20.30.40.40.50.60.8563-46-22-Methyl-1-butene0.050.10.10.20.20.30.40.40.50.60.7115-10-6Methyl ether0.040.080.10.20.20.20.30.30.40.50.6107-31-3Methyl formate0.030.060.080.10.10.20.20.20.30.40.4115-11-72-Methylpropene0.050.10.10.20.20.30.40.40.50.60.8504-60-91,3-Pentadiene0.050.10.10.20.20.30.30.40.50.60.7109-66-0Pentane0.050.10.10.20.20.30.40.40.50.60.8109-67-11-Pentene0.050.10.10.20.20.30.40.40.50.60.8646-04-82-Pentene, (E)-0.050.10.10.20.20.30.40.40.50.60.8April 15, 199910 - 25Reference Table 30 (continued)Quantityin Fireball (pounds)1,0005,00010,00020,00030,00050,00075,000100,000200,000300,000500,000Duration of Fireball (seconds)3.55.97.59.410.812.714.815.517.418.720.3CAS No.Chemical NameDistance (miles) at which Exposure for Duration of Fireball MayCause Second Degree Burns627-20-32-Pentene, (Z)-0.050.10.10.20.20.30.40.40.50.60.8463-49-0Propadiene0.050.10.10.20.20.30.40.40.50.60.874-98-6Propane0.050.10.10.20.20.30.40.40.50.60.8115-07-1Propylene0.050.10.10.20.20.30.40.40.50.60.874-99-7Propyne0.050.10.10.20.20.30.40.40.50.60.87803-62-5Silane0.050.10.10.20.20.30.40.40.50.60.7116-14-3Tetrafluoroethylene0.010.020.020.030.040.050.060.070.090.10.175-76-3Tetramethylsilane0.050.10.10.20.20.30.30.40.50.60.710025-78-2Trichlorosilane0.010.030.040.060.070.080.10.10.20.20.279-38-9Trifluorochloroethylene0.010.020.030.040.050.060.070.080.10.10.275-50-3Trimethylamine0.040.090.10.20.20.30.30.40.50.60.7689-97-4Vinyl acetylene0.050.10.10.20.20.30.40.40.50.60.875-01-4Vinyl chloride0.030.070.090.10.20.20.20.30.30.40.5109-92-2Vinyl ethyl ether0.040.090.10.20.20.20.30.30.40.50.675-02-5Vinyl fluoride0.010.020.030.040.050.060.080.090.10.10.275-35-4Vinylidene chloride0.020.050.070.090.10.10.20.20.30.30.475-38-7Vinylidene fluoride0.020.050.070.090.10.10.20.20.30.30.4107-25-5Vinyl methyl ether0.040.080.10.20.20.20.30.30.40.50.6April 15, 199910 - 26

## 11 ESTIMATING OFFSITE RECEPTORS

In Chapter 11

� How to estimate the number of offsite receptors potentially affected by your

worst-case and alternative scenarios.

� Where to find the data you need.

The rule requires that you estimate residential populations within the circle defined by the endpoint for your worst-case and alternative release scenarios. In addition, you must report in the RMP whether certain types of public receptors and environmental receptors are within the circles.

To estimate residential populations, you may use the most r ecent Census data or any other source of data that you believe is more accurate. Local authorities may be able to provide information on offsite receptors. You are not required to update Census data or conduct any surveys to develop your estimates. Census data are available in public libraries and in the La ndView system, which is available on CD-ROM (see box below). The rule requires that you estimate populations to two significant digits. For example, if there are 1,260 people wit hin the circle, you may report 1, 300 people. If the number of people is between 10 and 100, estimate to the nearest 10. If the number of people is less than 10, pr ovide the actual number.

How to obtain Census data and LandView

Census data can be found in publications of the Bureau of the Census, available in public libraries, including County and City Data Book

.

LandView ®III is a desktop mapping system that includes database extracts from EPA, the Bureau of the Census, the U.S. Geological Survey, the Nuclear Regulatory Commission, the Department of Transportation, and the Federal Emergency Management Agency. These databases are presented in a geographic context on maps that show jurisdictional boundaries, detailed networks of roads, rivers, and railroads, census block group and tract polygons, schools, hospitals, churches, cemeteries, airports, dams, and other landmark features.

CD-ROM for IBM-compatible PCS CD-TGR95-LV3-KIT $99 per disc (by region) or $549 for 11 disc set

U.S. Department of Commerce

Bureau of the Census

P.O. Box 277943 Atlanta, GA 30384-7943

Phone: 301-457-4100 (Customer Services -- orders) Fax: (888) 249-7295 (toll-free) Fax: (301) 457-3842 (local) Phone: ( 301) 457-1128 (Geography Staff -- content) http://www.census.gov/ftp/pub/geo/www/tiger/

Further information on LandView and other sources of Census data is available at the Bureau of the Census web site at www.census.gov.

April 15, 1999Chapter 11 Estimating Offsite Receptors

Census data are presented by Census tract. If your circle covers only a portion of the tract, you should develop an estimate for that portion. The easiest way to do this is to determine the population density per square mile (total population of the Census tract divided by the number of square miles in the tract) and apply that density figure to the number of square miles within your circle. Because there is likely to be considerable variation in actual densities within a Census tract, this number will be approximate. The rule, however, does not require you to correct the number.

Other public receptors must be noted in the RMP. If there are any sc hools, residences, hospitals, prisons, public recreational areas, or co mmercial, office, or industrial areas within the circle, you must report that. Any of these locations inhabited or occupied by the public at any time without restriction by the source is a public receptor. You are not required to develop a list of all institutions and areas; you must simply check off which types of receptors are within the circle. Most of these institutions or areas can be identified from local street maps. Recreational areas include public swimming pools, public parks, and other areas that are used for recreational activities (e.g., baseball fields). Co mmercial and industrial areas include shopping malls, strip malls, downtown business areas, industrial parks, etc. See EPA’s General Guidance for Risk Management Programs (40 CFR part 68) for further information on identifying public r eceptors.

Environmental r eceptors are defined as national or state parks, fore sts, or monuments; officially designated wildlife sanctuaries, preserves, or refuges; and Federal wilderness areas. All of these can be identified on local U.S. Geological Survey (USGS) maps (see box below). You are not required to locate each of these specifically. You are only required to check off in the RMP that these specific types of areas are within the circle. If any part of one of these r eceptors is within your circles, you must note that in the RMP.

Important: The rule does not require you to assess the likelihood, type, or severity of potential impacts on either public or environmental receptors. Identifying them as within the circle simply indicates that they could be adversely affected by the release.

April 15, 1999 11 - 2Chapter 11 Estimating Offsite Receptors

How to obtain USGS maps

The production of digital cartographic data and graphic maps comprises the largest component of the USGS National Mapping Program. The USGS's most familiar product is the 1:24, 000-scale Topographic Quadrangle Map. This is the primary scale of data produced, and depicts greater detail for a smaller area than intermediate-scale (1:50,000 and 1:100,000) and small-scale (1:250,000, 1:2,000,000 or smaller) pr oducts, which show selectively less detail for larger areas.

U.S. Geological Survey

508 National Center 12201 Sunrise Valley Drive Reston, VA 20192 Phone: ( 703) 648-4000 http://mapping.usgs.gov

To order USGS maps by fax, select, print, and complete one of the online forms and fax to 303-202-4693.

A list of the nearest commercial dealers is available at: http://mapping.usgs.gov/esic/usimage/dealers.html

For more information or ordering assistance, call 1-800-HELP-MAP, or write:

USGS Information Services

Box 25286 Denver, CO 80225

For additional information, contact any USGS Earth Science Information Center or call 1-800-USA-MAPS.

April 15, 1999 11 - 3Chapter 11 Estimating Offsite Receptors



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April 15, 1999 11 - 4

### 12 SUBMITTING OFFSI TE CONSEQUENCE ANALYSIS
INFORMATION FOR RI SK MANAGEMENT PLAN

In Chapter 12

 12.1 Information you are required to submit for worst-case scenarios for
toxic substances.

 12.2 Information you are required to submit for alternative scenarios for
toxic substances.

 12.3 Information you are required to submit for worst-case scenarios for
flammable substances.

 12.4 Information you are required to submit for alternative scenarios for
flammable substances.

For the offsite consequence analysis (OCA) component of the RMP you must provide information on your worst-case a nd alternative release scenario(s) for toxic and flammable regulated chemicals held above the threshold quantity. The re quirements for what information you must submit differ if your source has Program 1, Pr ogram 2, or Program 3 processes.

If your source has Program 1 processes, you must submit information on a worst-case

release scenario for each Program 1 process. If your source has Program 2 or Program 3 processes, you must provide information on one worst-case release for all toxic regulated substances present above the threshold quantity and one worst-case release scenario for all flammable regulated substances present above the threshold quantity. You may need to submit an additional worst-case scenario if a worst-case release from another part of the source would potentially affect public receptors different from those potentially affect ed by the initial worst-case scenario(s) for flammable and toxic regulated substances.

In addition to a worst-case release scenar io, sources with Program 2 and Program 3 processes must also provide information on altern ative release scenarios. Alternative releases are releases that could occur, other than the worst-case, that may result in concen trations, overpressures, or radiant heat that reach endpoints offsite. You must present information on one alternative release

scenario for each regulated toxic substance, including the s ubstance used for the worst-case release, held above the threshold quantity and one alternative release scenario to represent all flammable substances held above the threshold quantity. Th e types of documentation to submit are presented below for worst-case scenarios involving toxic su bstances, alternative s cenarios involving toxic substances, worst-case scenarios involving flammabl e substances, and alternative scenarios involving

flammable substances.



### 12.1 RMP Data Required for Worst-Case Scenarios for Toxic Substances

For worst-case scenarios involving toxic substances, you will have to submit the following information. See the RMP*eSubmit User Manual for complete instructions.

• Chemical name;

• Percentage weight of the regulated liquid toxic substance (if present in a mixture);

March 2009Chapter 12 Submitting Offsite Consequence Analysis Information for Risk Management Plan

Physical state of the chemical released (gas, liquid, refrigerated gas, gas liquefied by pressure); �

Model used (OCA or industry-specific guidance reference tables or modeling; name of other model used); �

Scenario (gas release or liquid spill and vaporization); � Quantity released (pounds); � Release rate (pounds per minute); � Duration of release (minutes) (10 minutes for gases; if you used OCA guidance for liquids, indicate either 10 or 60 minutes); �

Wind speed (meters per second) and stability class (1.5 meters per second and F stability unless you can show higher minimum wind speed or less stable atmosphere at all times during the last three years); �

Topography (rural or urban); � Distance to endpoint (miles, rounded to two significant digits); � Population within distance to endpoint (residential population rounded to two significant digits); �

Public receptors within the distance to endpoint (schools, residences, hospitals, prisons, recreation areas, co mmercial, office or industrial areas); �

Environmental r eceptors within the distance to endpoint (national or state parks, fore sts, or monuments; officially des ignated wildlife sanctuaries, preserves, or refuges; Federal wilderness areas); and �

Passive mitigation measures considered (dikes, enclosures, berms, drains, sumps, other). �



### 12.2 RMP Data Required for Alternative Scenarios for Toxic Substances

For alternative scenarios involving toxic su bstances held above the thres hold quantity in a Program 2 or Program 3 process, you will have to submit the following information. See the Risk Manag ement Plan

Data Elements G uide for complete instructions.

Chemical name; � Percentage weight of the regulated liquid toxic su bstance (if present in a mixture); � Physical state of the chemical released (gas, liquid, refrigerated gas, gas liquefied by pressure); �

Model used (OCA or industry-specific guidance reference tables or modeling; name of other model used); �

Scenario (transfer hose failure, pipe leak, vessel leak, overfilling, rupture disk/relief valve, excess flow valve, other); �

Quantity released (pounds); � Release rate (pounds per minute); � Duration of release (minutes) (if you used OCA guidance, indicate either 10 or 60 minutes); � Wind speed (meters per second) and stability class (3.0 meters per second and D stability if you use OCA guidance, otherwise use typical meteorological conditions at your site); �

Topography (rural or urban); � Distance to endpoint (miles, rounded to two significant digits); � Population within distance to endpoint (residential population rounded to two significant digits); �

April 12, 1999 12 - 2Chapter 12 Submitting Offsite Consequence Analysis Information for Risk Management Plan

Public receptors within the distance to endpoint (schools, residences, hospitals, prisons, recreation areas, co mmercial, office, or industrial areas); �

Environmental r eceptors within the distance to endpoint (national or state parks, fore sts, or monuments; officially des ignated wildlife sanctuaries, preserves, or refuges; Federal wilderness areas); �

Passive mitigation measures considered (dikes, enclosures, berms, drains, sumps, other); and � Active mitigation measures considered (sprinkler system, deluge system, water curtain, neutralization, excess flow valve, flares, scrubbers, emergency shutdown system, other). �



### 12.3 RMP Data Required for Worst-Case Scenarios for Flammable Substances

For worst-case scenarios involving flammable su bstances, you w ill have to submit the following information. See the Risk Manag ement Plan Data Elements G uide for complete instructions.

Chemical name; � Model used (OCA or industry-specific guidance reference tables or modeling; name of other model used); �

Scenario (vapor cloud explosion); � Quantity released (pounds); � Endpoint used (for vapor cloud explosions use 1 psi); � Distance to endpoint (miles, rounded to two significant digits); � Population within distance to endpoint (residential population rounded to two significant digits); �

Public receptors within the distance to endpoint (schools, residences, hospitals, prisons, recreation areas, co mmercial, office, or industrial areas); �

Environmental r eceptors within the distance to endpoint (national or state parks, fore sts, or monuments, officially designated wildlife sanctuaries, preserves, or refuges, Federal wilderness areas); and �

Passive mitigation measures considered (blast walls, other). �



### 12.4 RMP Data Required for Alternative Scenarios for Flammable Substances

For alternative scenarios involving flammable su bstances held above the thres hold quantity in a Program 2 or Program 3 process, you will have to submit the following information. See the Risk Management Plan Data Elements G uide for complete instructions.

Chemical name; � Model used (OCA or industry-specific guidance reference tables or modeling; name of other model used); �

Scenario (vapor cloud explosion, fireball, BLEVE, pool fire, jet fire, vapor cloud fire, other); � Quantity released (pounds); � Endpoint used (for vapor cloud explosions, the endpoint is 1 psi overpressure; for a fireball the endpoint is 5 kw/m 2 for 40 seconds. A lower flammability limit (expressed as a percentage) may be listed as specified in NFPA documents or other generally recognized sources; these are listed in the OCA Guidance); �

Distance to endpoint (miles, rounded to two significant digits); �

April 12, 1999 12 - 3Chapter 12 Submitting Offsite Consequence Analysis Information for Risk Management Plan

• Population within distance to endpoint (residential population rounded to two significant digits);

• Public receptors within the distance to endpoint (schools, residences, hospitals, prisons, recreation areas, commercial, o ffice, or industrial areas);

• Environmental receptors within the distance to endpoint (national or state parks, forests, or monuments, officially designated wildlife sanctuaries, preserves, or refuges, Federal wilderness areas);

• Passive mitigation measures considered (e.g., dikes, fire walls, blast walls, enclosures, other);
and

• Active mitigation measures considered (e.g., sprinkler system, deluge system, water curtain, excess flow valve, other).



### 12.5 Submitting RMPs

EPA has made RMP*eSubmit available to complete and file your RMP. RMP*eSubmit does the following:

• Provides a user-friendly, web-based RMP Subm ission System via EPA’s secure Central Data Exchange (CDX).

• Performs data quality checks, accepts limited graphics, and provides on-line help including defining data elements and providing instructions.

• Online reporting simplifies the process. It saves you time, and improves data quality and security.

• EPA uses industry-standard technology, incl uding encryption used by most commercial banks, as well as stringent user ID and password protocols to protect your information.

• You will be able to access your RMP online at any time.

• For a facility to submit their RMP, the certifier will first be required to set up a CDX account (or use their current one if the facility already submits data via CDX). Instructions for obtaining a CDX account and using RMP*eSubmit can be found at: www.epa.gov/emergencies/rmp

.

• Upon approval of the document in submission , a confirmation e-mail will be sent to the
certifier.



### 12.6 Other Required Documentation

Besides the information you are required to submit in your RMP, you must maintain other records of your offsite consequence analysis on site. Under 40 CFR 68.39, you must maintain the following records:



### • For worst-case scenarios, a description of the ve ssel or pipeline and substance selected as the worst case, the assumptions and parameters used , and the rationale for selection. Assumptions include any administrative controls and any passive mitigation systems that were used to limit the quantity that could be released. You must document that anticipated effects of these controls and systems on the release quantity and rate.

March 2009 12 - 4

### • For alternative release scenarios, a description of the scenarios identified the assumptions and parameters used, and the rationale for selection of the specific scenarios. Assumptions include any administrative controls and any passive mitigation systems that were used to limit the quantity that could be released. You must document that anticipated effects of these controls and systems on the release quantity and rate.



### • Documentation of estimated quantity released, release rate, and duration of the release.



### • Methodology used to determine distance to an endpoint.



### • Data used to estimate populations and environmental receptors potentially affected.

You are required to maintain these records for five years.

March 2009 12 - 5Chapter 12 Submitting Offsite Consequence Analysis Information for Risk Management Plan

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April 12, 1999 12 - 6

## AP P E NDI X A

REF E RENCES F O R CONS EQUENCE ANALYS I S M ETHODS

A

p r i l 15, 1999

## AP P E NDI X A R EF ERENCES F O R CONS EQUENCE ANALYS I S

M E T HODS

E x h i b i t A

- 1 l i sts r e f e r e n c e s th a t m a y pr ovide us e f ul inf or m a t ion f o r

m ode ling or c a lc ula t ion m e t hods

t h a t c ould b e us e d in t h e of f s it e c ons e q ue nc e a n a l y s e s

. T his e x hib it is not int e nde d t o b e a c o m p le t e lis t ing of

r e f e r e nc e s t h a t m a y b e us e d in t h e c ons e q ue nc e a n a l y s is ; a n y a p p r op r i a t e m ode l or m e t hod m a y b e us e d

.

A

p r i l 15, 1999Ap p e ndix A

Re f e r e nc e s f o r Cons e q ue nc e Ana l y s is Me thods



### E x hibit A

- 1

S e l ect ed Ref e r e n ces f o r In f o r m at i o n on Con s eq u e n ce An al ysi s M e t h od s

Ce n t e r fo r Pro c e s s Safe t y o f t h e A m e r i c an I n s t i t u t e o f Ch e m i c a l Engine e r s ( A I C hE)

. G uide line s for

E

v aluating the C harac te ristic s of V apor C loud E x

plosions, F lash F ire s, and B L EVEs

. Ne w Yor k:

A I C h E

, 1994.

Ce n t e r fo r Pro c e s s Safe t y o f t h e A m e r i c an I n s t i t u t e o f Ch e m i c a l Engine e r s ( A I C hE)

. G uide line s for U s e of

V

apor C loud D ispe rsion M ode ls , S e c ond Ed. Ne w Yor k: AI C hE, 1996.

Ce n t e r fo r Pro c e s s Safe t y o f t h e A m e r i c an I n s t i t u t e o f Ch e m i c a l Engine e r s ( A I C hE)

. I nte rnational

C onfe re nc e and W ork shop on M ode ling and M itigating the C onse que nc e s of A c c ide ntal R e le ase s of H azardous M ate rials

, S e pte m b e r 26- 29, 1995. N e w Y o r k : A I C h E

, 1995.

F e d e r a l E mer g e n c y M a n a g emen t A g e n c y , U

. S

. D e p a r t men t o f T r a n s p o r t a t ion, U.S

. Envir onm e n t a l P r o t e c t ion Age nc y

. H andbook of C h e m ic al H azard A naly sis P roc e dure s

. 1989.

Mad s e n , W arre n W

. an d Ro b e rt C. W a g n e r. " A n A c c u rat e Me t hodology f

o r

M ode ling t h e C h arac t e ri s t i c s o f

Ex p los ion Ef f e c t s

. " P roc e ss Safe ty P rogre ss , 13 ( J u l y 1994)

, 171- 175.

M e r c x , W.P

. M ., D.M

. J ohns on, a nd J

. P u t t o c k

. "Va lida t ion of S c a ling T e c hniq ue s f o r

Ex p e r i m e n t a l Va p o r C loud Ex p los ion I nve s t iga t ions ." P roc e ss Safe ty P rogre ss , 14 ( A pr i l 1995)

, 120.

M e r c x, W

. P

. M

. , R

. M

. M

. v a n W e e s , a n d G. Opsc hoor

. "C ur r e nt R e s e a r c h a t T N O on Va p o r C loud Ex p los ion

M ode lling." P roc e ss Safe ty P rogre ss , 12 ( O c t o b e r 1993)

, 222.

P r ugh, R i c h a r d W. "Q ua nt it a t ive Eva lua t ion of F i r e b a ll H azard s

. " P roc e ss Safe ty P rogre ss , 13 ( A pr i l 1994)

, 83- 91.

S c he ue r m a nn, K l a u s P

. "S t udie s Ab out t h e I n f lue nc e of T u r b ule nc e on t h e C our s e of Ex p los ions ." P r o ces s Safe ty P rogre ss , 13 ( O c t o b e r 1994)

, 219.

T N O Bu re au fo r I n d u s t r i a l Safe t y , N e t h e r l a n d s O r g a n i zat ion f o r

Ap p lie d S c ie nt if ic R e s e a r c h. M e thods for

the C alc ulation of the P h y sic al E ffe c t s

. T h e Ha gue , t h e Ne t h e r la nds : C o m m

i t t e e f

o r

t h e P r e ve nt ion

o f

D i s a ste r s , 1997.

T N O Bu re au fo r I n d u s t r i a l Safe t y , N e t h e r l a n d s O r g a n i zat ion f o r

Ap p lie d S c ie nt if ic R e s e a r c h. M e thods for

the C alc ulation of the P h y sic al E ffe c ts of the E s c ape of D ange rous M ate rial ( L iquids and G ase s)

. Voor b u r g , t h e Ne t h e r la nds : T N O ( C o m m

i s s ione d b y Dir e c t or a t e

- G e ne r a l of La b our )

, 1980.

T N O Bu re au fo r I n d u s t r i a l Safe t y , N e t h e r l a n d s O r g a n i zat ion f o r

Ap p lie d S c ie nt if ic R e s e a r c h. M e thods for

the C alc ulation of the P h y sic al E ffe c ts R e sulting from R e le ase s of H azardous M ate rials

. R ijs w ijk,

t h e Ne t h e r la nds : T N O ( C o m m

i s s ione d b y Dir e c t or a t e

- G e ne r a l of La b our )

, 1992.

T N O Bu re au fo r I n d u s t r i a l Safe t y , N e t h e r l a n d s O r g a n i zat ion f o r

Ap p lie d S c ie nt if ic R e s e a r c h. M e thods for

the D e te rm ination of P ossible D a m age to P e ople and O bje c ts R e sulting from R e le ase s of

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Re f e r e nc e s f o r Cons e q ue nc e Ana l y s is Me thods

H

azardous M ate rials

. R ijs w ijk, t h e Ne t h e r la nds : T N O ( C o m m

i s s ione d b y Dir e c t or a t e

- G e ne r a l of

L a bo u r )

, 1992.

T oum a , J a w a d S ., e t a l

. "P e r f o r m a n c e Eva lua t ion of De ns e G a s Dis p e r s ion M ode ls ." J ournal of A pplie d

M

e te orology

, 3 4 (Marc h 1995)

, 603- 615.

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. Envir onm e n t a l P r o t e c t ion Age nc y , F e de r a l Em e r ge nc y M a n a g emen t A g e n c y , U

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. D e p a r t men t o f

T r a n s p o r t a t ion. T e c hnic al G uidanc e for H azards A naly sis, E m e rge nc y P lanning for E x tre m e ly

H

azardous Substanc e s

. D ecemb er 1987.

U.S

. Envir onm e n t a l P r o t e c t ion Age nc y , O f f i c e of Air Q u a lit y P l a nning a nd S t a nda r d s

. W ork book of

Sc re e ning T e c hnique s for A sse ssing I m

pac ts of T o x i c A ir P ollutants

. E P A

- 450/4- 88- 009.

S e pte m b e r 1988.

U.S

. Envir onm e n t a l P r o t e c t ion Age nc y , O f f i c e of Air Q u a lit y P l a nning a nd S t a nda r d s

. G uidanc e on the

A

pplic ation of R e fine d D ispe rsion M ode ls for H azardous/T ox ic A ir R e le ase

. E P A

- 454/R

- 93- 002.

M a y 1993.

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. Envir onm e n t a l P r o t e c t ion Age nc y , O f f i c e of P ollut ion P r e ve nt ion a nd T o x i c S u bsta n c e s

. F lam m able

G ase s and L iquids and T h e ir H azards

. E P A 744- R

- 94- 002. F e br u a r y 1994.

A

p r i l 15, 1999 A - 3

## AP P E NDI X B

TOXI C S U BS TANCES

A

p r i l 15, 1999

## AP P E NDI X B T OXI C S U BS TANCES

B

. 1 D ata f o r T o x i c Subs tanc e s

T h e e x hib it s in t his s e c t ion of Ap p e ndix B p r ovide t h e da t a ne e d e d t o c arry o u t t h e c a l c u l a t ions f o r

r e gula t e d t o x i c s u bsta n c e s u s ing t h e m e t hods p r e s e n t e d in t h e t e x t of t his guida nc e

. Ex hib it B

- 1 p r e s e n t s da t a f o r

t o x i c ga s e s , Ex hib it B

- 2 p r e s e n t s da t a f o r

t o x i c liq uids , a nd Ex hib it B

- 3 p r e s e n t s da t a f o r

s e ve r a l

to xi c su bsta n c e s c o m m only f

ound in w a t e r s olut ion a nd f o r

ole um

. Ex hib it B

- 4 p r ovide s t e m p e r a t ur e

c o r r e c t ion f a c t o r s t h a t c a n b e us e d t o c o r r e c t t h e r e le a s e r a t e s e s t i m a t e d f o r

p ool e v a p or a t ion of t o x i c liq uids

o o t h at are re l e as e d at t e m p e rat u r e s b e t w e e n 2 5 C t o 5 0 C.

T h e de r iva t ion of t h e f

a c t o r s p r e s e n t e d in Ex hib it s B

- 1
- B

- 4 is dis c u s s e d in Ap p e ndix D. T h e da t a

us e d t o de ve lop t h e f

a c t o r s in Ex hib it s B

- 1 a nd B

- 2 a r e p r im a r ily f

r o m De s ign I n s t i t u t e f

o r

P h y s ic a l P r o p e r t y D a t a (D I PPR), A m e r i c an I n s t i t u t e o f Ch e m i c a l Engine e r s , P h y sic al and T h e r m ody nam ic P rope rtie s of P ure C

h e m ic als, D ata C o m pilation

. O t h e r s our c e s , inc luding t h e Na t iona l Lib rary o f Me d i c i n e ’s H azar dous

S u bsta n c e s D a ta ba n k ( H S D B ) a n d th e K irk

- O thm e r E

n c

y c lope dia of C h e m ic al T e c hnology

, w e re u s e d fo r
E x h i b i t s B-1 an d B-2 i f d a t a w e re n o t av ai l a b l e fro m t h e D I PPR c o m p i l a t ion. T h e f

a c t o r s in Ex hib it B

- 3

w e r e de ve lop e d us ing da t a p r im a r ily f

r o m P e rry 's C h e m ic al E ngine e rs' H andbook a nd t h e Ki r k-O t h m er
E

n c

y c lope dia of C h e m ic al T e c hnology

. T h e t e m p e r a t ur e c o r r e c t ion f a c t o r s in Ex hib it B

- 4 w e r e de ve lop e d

us ing va p o r p r e s s u r e da t a de r ive d f r o m t h e va p o r p r e s s u r e c o e f f i c i e n t s in t h e DI PPR c o m p i l a t ion.

A

p r i l 15, 1999Exhibit B-1DataforToxic GasesCASMolecularRatioofToxic EndpointaLiquid FactorBoiling(LFB)DensityFactor (DF)(Boiling)GasFactor(GF)kVaporPressure@25 C(psia)oReferenceTablebNumberChemicalNameWeightSpecificHeatsmg/LppmBasis7664-41-7Ammonia (anhydrous)c17.031.310.14200ERPG-20.0730.7114145Buoyantd7784-42-1Arsine77.951.280.00190.6EHS-LOC(IDLH)0.230.3030239Dense10294-34-5Borontrichloride117.171.150.0102EHS-LOC(Tox)e0.220.363622.7Dense7637-07-2Borontrifluoride67.811.200.02810EHS-LOC(IDLH)0.250.3128fDense7782-50-5Chlorine70.911.320.00873ERPG-20.190.3129113Dense10049-04-4Chlorinedioxide67.451.250.00281EHS-LOCequivalent(IDLH)g0.150.302824.3Dense506-77-4Cyanogenchloride61.471.220.03012EHS-LOCequivalent(Tox)h0.140.412623.7Dense19287-45-7Diborane27.671.170.00111ERPG-20.131.1317fBuoyantd75-21-8Ethyleneoxide44.051.210.09050ERPG-20.120.552225.4Dense7782-41-4Fluorine38.001.360.00392.5EHS-LOC(IDLH)0.350.3222fDense50-00-0Formaldehyde (anhydrous)c30.031.310.01210ERPG-20.100.591975.2Dense74-90-8Hydrocyanicacid27.031.300.01110ERPG-20.0790.721814.8Buoyantd7647-01-0Hydrogenchloride(anhydrous)c36.461.400.03020ERPG-20.150.4121684Dense7664-39-3Hydrogenfluoride(anhydrous)c20.011.400.01620ERPG-20.0660.511617.7Buoyanti7783-07-5Hydrogenselenide80.981.320.000660.2EHS-LOC(IDLH)0.210.2531151Dense7783-06-4Hydrogensulfide34.081.320.04230ERPG-20.130.5120302Dense74-87-3Methylchloride50.491.260.82400ERPG-20.140.482483.2Dense74-93-1Methylmercaptan48.111.200.04925ERPG-20.120.552329.2Dense10102-43-9Nitricoxide30.011.380.03125EHS-LOC(TLV)j0.210.3819fDense75-44-5Phosgene98.921.170.000810.2ERPG-20.200.353327.4DenseApril15,1999B -2Exhibit B-1 (continued)CASMolecularRatioofToxic EndpointaLiquid FactorBoiling(LFB)DensityFactor (DF)(Boiling)GasFactor(GF)kVaporPressure@25 C(psia)oReferenceTablebNumberChemicalNameWeightSpecificHeatsmg/LppmBasis7803-51-2Phosphine34.001.290.00352.5ERPG-20.150.6620567Dense7446-09-5Sulfurdioxide(anhydrous)64.071.260.00783ERPG-20.160.332758.0Dense7783-60-0Sulfurtetrafluoride108.061.300.00922EHS-LOC(Tox)e0.250.25(at -73C)o36293DenseNotes:a3Toxicendpointsarespecifiedin Appendix A to 40CFR part68in unitsofmg/L.Toconvertfromunitsofmg/Lto mg/m, multiplyby1,000.Toconvertmg/Ltoppm,usethefollowing equation:Endpointmg/L×1,000×24.5�EndpointppmMolecularWeightb"Buoyant"in the Reference Table columnrefersto the tablesforneutrallybuoyant gasesand vapors; "Dense"refersto the tablesfordensegasesand vapors.SeeAppendix D,Section D.4.4,formoreinformation on thechoiceofreferencetables.cSeeExhibit B-3ofthisappendix fordataon watersolutions.dGasesthatarelighterthanairmaybehaveasdensegasesupon releaseifliquefiedunderpressureorcold; considertheconditionsofreleasewhenchoosing theappropriate table.eLOC isbased on the IDLH-equivalent level estimated fromtoxicitydata.ofCannot beliquefiedat25C.gNot anEHS;LOC-equivalentvalue wasestimatedfromone-tenthofthe IDLH.hNot an EHS;LOC-equivalent value wasestimated fromone-tenth ofthe IDLH-equivalent level estimated fromtoxicitydata.iHydrogen fluorideislighterthanair,but maybehaveasadensegasupon releaseundersomecircumstances(e.g.,releaseunderpressure,high concentration in thereleased cloud)becauseofhydrogen bonding; considerthe conditionsofrelease when choosing the appropriate table.jLOC basedonThresholdLimit Value (TLV)-Time-weightedaverage (TWA)developedbythe AmericanConference ofGovernmental Industrial Hygienists(ACGIH).kUseGFforgasleaksunderchoked (maximum)flow conditions.April15,1999B -3Exhibit B-2Data forToxicLiquidsCASNumberChemicalNameWeightMolecularat25C(mm Hg)PressureVaporoToxicEndpointaLiquid FactorsFactor(DF)DensityFactor(LLF)LeakLiquidIReference Tablebmg/LppmBasisAmbient(LFA)Boiling(LFB)WorstCaseAlternativeCase107-02-8Acrolein56.062740.00110.5ERPG-20.0470.120.5840DenseDense107-13-1Acrylonitrile53.061080.07635ERPG-20.0180.110.6139DenseDense814-68-6Acrylylchloride90.511100.000900.2EHS-LOC(Tox)c0.0260.150.4454DenseDense107-18-6Allylalcohol58.0826.10.03615EHS-LOC(IDLH)0.00460.110.5841DenseBuoyantd107-11-9Allylamine57.102420.00321EHS-LOC(Tox)c0.0420.120.6436DenseDense7784-34-1Arsenoustrichloride181.28100.011EHS-LOC(Tox)c0.00370.210.23100DenseBuoyantd353-42-4Borontrifluoridecompoundwithmethyl ether (1:1)113.89110.0235EHS-LOC(Tox)c0.00300.160.4948DenseBuoyantd7726-95-6Bromine159.812120.00651ERPG-20.0730.230.16150DenseDense75-15-0Carbon disulfide76.143590.1650ERPG-20.0750.150.3960DenseDense67-66-3Chloroform119.381960.49100EHS-LOC(IDLH)0.0550.190.3371DenseDense542-88-1Chloromethylether114.9629.40.000250.05EHS-LOC(Tox)c0.00800.170.3763DenseDense107-30-2Chloromethylmethylether80.511990.00180.6EHS-LOC(Tox)c0.0430.150.4651DenseDense4170-30-3Crotonaldehyde70.0933.10.02910ERPG-20.00660.120.5841DenseBuoyantd123-73-9Crotonaldehyde,(E)-70.0933.10.02910ERPG-20.00660.120.5841DenseBuoyantd108-91-8Cyclohexylamine99.1810.10.1639EHS-LOC(Tox)c0.00250.140.5641DenseBuoyantd75-78-5Dimethyldichlorosilane129.061410.0265ERPG-20.0420.200.4651DenseDense57-14-71,1-Dimethylhydrazine60.101570.0125EHS-LOC(IDLH)0.0280.120.6238DenseDense106-89-8Epichlorohydrin92.5317.00.07620ERPG-20.00400.140.4257DenseBuoyantd107-15-3Ethylenediamine60.1012.20.49200EHS-LOC(IDLH)0.00220.130.5443DenseBuoyantd151-56-4Ethyleneimine43.072110.01810EHS-LOC(IDLH)0.0300.100.5840DenseDense110-00-9Furan68.086000.00120.4EHS-LOC(Tox)c0.120.140.5245DenseDense302-01-2Hydrazine32.0514.40.0118EHS-LOC(IDLH)0.00170.0690.4848BuoyantdBuoyantdApril15,1999B -4Exhibit B-2 (continued)CASNumberChemicalNameWeightMolecularat25C(mm Hg)PressureVaporoToxicEndpointaLiquid FactorsFactor(DF)DensityFactor(LLF)LeakLiquidIReference Tablebmg/LppmBasisAmbient(LFA)Boiling(LFB)WorstCaseAlternativeCase13463-40-6Iron,pentacarbonyl-195.90400.000440.05EHS-LOC(Tox)c0.0160.240.3370DenseDense78-82-0Isobutyronitrile69.1132.70.1450ERPG-20.00640.120.6337DenseBuoyantd108-23-6Isopropylchloroformate122.55280.1020EHS-LOC(Tox)c0.00800.170.4552DenseDense126-98-7Methacrylonitrile67.0971.20.00271EHS-LOC(TLV)e0.0140.120.6138DenseDense79-22-1Methylchloroformate94.501080.00190.5EHS-LOC(Tox)c0.0260.160.4058DenseDense60-34-4Methyl hydrazine46.0749.60.00945EHS-LOC(IDLH)0.00740.0940.5642DenseBuoyantd624-83-9Methyl isocyanate57.054570.00120.5ERPG-20.0790.130.5245DenseDense556-64-9Methyl thiocyanate73.12100.08529EHS-LOC(Tox)c0.00200.110.4551DenseBuoyantd75-79-6Methyltrichlorosilane149.481730.0183ERPG-20.0570.220.3861DenseDense13463-39-3Nickelcarbonyl170.734000.000670.1EHS-LOC(Tox)c0.140.260.3763DenseDense7697-37-2Nitricacid(100%)f63.0163.00.02610EHS-LOC(Tox)c0.0120.120.3273DenseDense79-21-0Peraceticacid76.0513.90.00451.5EHS-LOC(Tox)c0.00290.120.4058DenseBuoyantd594-42-3Perchloromethylmercaptan185.8760.00761EHS-LOC(IDLH)0.00230.200.2981DenseBuoyantd10025-87-3Phosphorusoxychloride153.3335.80.00300.5EHS-LOC(Tox)c0.0120.200.2980DenseDense7719-12-2Phosphorustrichloride137.331200.0285EHS-LOC(IDLH)0.0370.200.3175DenseDense110-89-4Piperidine85.1532.10.0226EHS-LOC(Tox)c0.00720.130.5741DenseBuoyantd107-12-0Propionitrile55.0847.30.00371.6EHS-LOC(Tox)c0.00800.100.6337DenseBuoyantd109-61-5Propylchloroformate122.5620.00.0102EHS-LOC(Tox)c0.00580.170.4552DenseBuoyantd75-55-8Propyleneimine57.101870.1250EHS-LOC(IDLH)0.0320.120.6139DenseDense75-56-9Propyleneoxide58.085330.59250ERPG-20.0930.130.5940DenseDense7446-11-9Sulfurtrioxide80.062630.0103ERPG-20.0570.150.2691DenseDense75-74-1Tetramethyllead267.3322.50.00400.4EHS-LOC(IDLH)0.0110.290.2496DenseDense509-14-8Tetranitromethane196.0411.40.00400.5EHS-LOC(IDLH)0.00450.220.3078DenseBuoyantdApril15,1999B -5Exhibit B-2 (continued)CASNumberChemicalNameWeightMolecularat25C(mm Hg)PressureVaporoToxicEndpointaLiquid FactorsFactor(DF)DensityFactor(LLF)LeakLiquidIReference Tablebmg/LppmBasisAmbient(LFA)Boiling(LFB)WorstCaseAlternativeCase7550-45-0Titaniumtetrachloride189.6912.40.0202.6ERPG-20.00480.210.2882DenseBuoyantd584-84-9Toluene2,4-diisocyanate174.160.0170.00701EHS-LOC(IDLH)0.0000060.160.4059BuoyantdBuoyantd91-08-7Toluene2,6-diisocyanate174.160.050.00701EHS-LOC(IDLH)g0.0000180.160.4059BuoyantdBuoyantd26471-62-5Toluenediisocyanate(unspecified isomer)174.160.0170.00701EHS-LOCequivalent(IDLH)h0.0000060.160.4059BuoyantdBuoyantd75-77-4Trimethylchlorosilane108.642310.05011EHS-LOC(Tox)c0.0610.180.5741DenseDense108-05-4Vinylacetatemonomer86.091130.2675ERPG-20.0260.150.5345DenseDenseNotes:a3Toxicendpointsarespecifiedin theAppendix A to 40CFR part68in unitsofmg/L.Toconvertfromunitsofmg/Lto mg/m,multiplyby1,000.Toconvertmg/Lto ppm,usethefollowing equation:EndpointppmEndpointmg/L×1,000×24.5�MolecularWeightb"Buoyant"in the Reference Table columnrefersto the tablesforneutrallybuoyant gasesand vapors; "Dense"refersto the tablesfordensegasesand vapors.SeeAppendix D,Section D.4.4,formoreinformation on thechoiceofreferencetables.cLOC isbased on IDLH-equivalent level estimated fromtoxicitydata.dUse dense gastable ifsubstance isat anelevatedtemperature.eLOC basedonThresholdLimit Value (TLV)-Time-weightedaverage (TWA)developedbythe AmericanConference ofGovernmental Industrial Hygienists(ACGIH).fSeeExhibit B-3ofthisappendix fordataon watersolutions.gLOC forthisisomerisbased on IDLHfortoluene 2,4-diisocyanate.hNot anEHS;LOC-equivalent valueisbased on IDLHfortoluene2,4-diisocyanate.iUse the LLFonlyforleaksfromtanksat atmospheric pressure.April15,1999B -6Exhibit B-3Data forWaterSolutionsofToxicSubstancesand forOleumForWind Speedsof1.5 and 3.0 MetersperSecond (m/s)RegulatedToxicEndpointaInitial10-min.Average VaporLiquid Factorat25CoDensityLiquidReference TablebCASSubstanceMolecularConcen-Pressure(mm Hg)(LFA)FactorLeakNumberinSolutionWeightmg/LppmBasistration(Wt %)1.5m/s3.0m/s1.5m/s3.0m/s(DF)Factor(LLF)WorstAlternative7664-41-7Ammonia17.030.14200ERPG-2303322480.0260.0190.5543BuoyantBuoyant242411840.0190.0140.5444BuoyantBuoyant201901480.0150.0110.5344BuoyantBuoyant50-00-0Formaldehyde30.0270.01210ERPG-2371.51.40.00020.00020.4453BuoyantBuoyant7647-01-0Hydrochloric36.460.03020ERPG-23878550.0100.00700.4157DenseBuoyantdacid3767480.00850.00620.4257DenseBuoyantd36c56420.00720.00530.4257DenseBuoyantd34c38290.00480.00370.4256DenseBuoyantd30c13120.00160.00150.4255BuoyantdBuoyantd7664-39-3Hydrofluoric20.010.01620ERPG-2701241070.0110.0100.3961BuoyantBuoyantacid5016150.00140.00130.4158BuoyantBuoyant7697-37-2Nitricacid63.010.02610EHS-9025220.00460.00400.3371DenseBuoyantdLOC(IDLH)8517160.00320.00290.3370DenseBuoyantd8010.2100.00190.00180.3370DenseBuoyantd8014-95-7Oleum-basedon SO380.06(SO)30.0103ERPG-230 (SO)33.5 (SO)33.4 (SO)30.00080.00070.2593BuoyantdBuoyantdNotes:aToxicendpointsarespecifiedin theAppendix A to 40CFR part68in unitsofmg/L.SeeNotesto Exhibit B-1orB-2forconverting to otherunits.b"Buoyant"in the Reference Table columnrefersto the tablesforneutrallybuoyant gasesand vapors; "Dense"refersto the tablesfordensegasesand vapors.SeeAppendix D,Section D.4.4,formoreinformation on thechoiceofreferencetables.cHydrochloricacid in concentrationsbelow 37percent isnot regulated.dUse dense gastable ifsubstance isat anelevatedtemperature.April15,1999B -7

### E x hibit B

- 4

T e m p er at ur e Cor r ect ion F a ct or s f o r L i quids E vapor at ing f r om P ool s at T e m p er at ur es

o o o o 

### B e t w een 25 C and 50 C ( 77 F and 122 F )

CAS

Num b e r Che m i c al Nam e P o i n t ( C ) B o ilin g

o T emp era t u re C o rrect ion F a ct or ( T C F )

30 C o (86 F ) o 35 C (95 F ) o

o 40 C (104 F ) o

o 45 C (113 F ) o

o 50 C (122 F ) o

o

107-02-8 A c r o l e i n 52. 69 1. 2 1

. 4 1. 7 2

. 0 2. 3

107-13-1 A c r y l o n i t r i l e 77. 35 1. 2 1

. 5 1. 8 2

. 1 2. 5

814-68-6 A c r y l y

l c h l o ri d e 75. 00 ND ND ND ND ND

107-18-6 A l l y l a l c ohol 9 7

. 0 8 1

. 3 1

. 7 2

. 2 2

. 9 3

. 6

107-11-9 A l l y l a m i n e 53. 30 1. 2 1

. 5 1. 8 2

. 1 2. 5

7784-34-1 A rs e nous tr ic hlor ide 130. 06 ND ND ND ND ND

353-42-4 B o r o n t r i f

l u o r i d e c o m p ound with

m e t h y

l e t h e r (1: 1 ) 126. 85 ND ND ND ND ND

7726-95-6 B ro m i n e 58. 75 1. 2 1

. 5 1. 7 2

. 1 2. 5

75-15-0 C a r bo n d i s u l f i d e 46. 22 1. 2 1

. 4 1. 6 1

. 9 L F B

67-66-3 C h l o r o f o r m 61. 18 1. 2 1

. 5 1. 8 2

. 1 2. 5

542-88-1 C h l o r o m e t h y

l e t h e r 104. 85 1. 3 1

. 6 2. 0 2

. 5 3. 1

107-30-2 C h l o r o m e t h y

l m e t h y

l e t h e r 59. 50 1. 2 1

. 5 1. 8 2

. 1 2. 5

4170-30-3 C ro t o n a l d e h y d e 104. 10 1. 3 1

. 6 2. 0 2

. 5 3. 1

123-73-9 C ro t o n a l d e h y d e , (E )

- 102. 22 1. 3 1

. 6 2. 0 2

. 5 3. 1

108-91-8 C y c l o h e x y l a m i n e 134. 50 1. 3 1

. 7 2. 1 2

. 7 3. 4

75-78-5 D i m e t h y

l d i c h l o r o s i l a n e 70. 20 1. 2 1

. 5 1. 8 2

. 1 2. 5

57-14-7 1

, 1 -Di m e t h y

l h y d ra z i n e 63. 90 ND ND ND ND ND

106-89-8 E pi c h l o ro h y d r i n 118. 50 1. 3 1

. 7 2. 1 2

. 7 3. 4

107-15-3 E t h y

l e n e d i a m i n e 36. 26 1. 3 1

. 8 L F B L F B L F B

151-56-4 E t h y

l e n e i m i n e 55. 85 1. 2 1

. 5 1. 8 2

. 2 2. 7

110-00-9 F u r a n 31. 35 1. 2 L F B L F B L F B L F B

302-01-2 H y d ra z i n e 113. 50 1. 3 1

. 7 2. 2 2

. 9 3. 6

13463-40-6 I ro n , pe n t acar b o n y l

- 102. 65 ND ND ND ND ND

78-82-0 I s o bu t y ro n i t r i l e 103. 61 1. 3 1

. 6 2. 0 2

. 5 3. 1

108-23-6 I s o pro p y l c h l o ro f o rm a t e 104. 60 ND ND ND ND ND

126-98-7 M e t h a c r y l o n i t r i l e 90. 30 1. 2 1

. 5 1. 8 2

. 2 2. 6

79-22-1 M e t h y

l c h l o ro f o rm a t e 70. 85 1. 3 1

. 6 1. 9 2

. 4 2. 9

60-34-4 M e t h y

l h y d r a z i n e 87. 50 ND ND ND ND ND

624-83-9 M e t h y

l i s o c y a n a t e 38. 85 1. 2 1

. 4 L F B L F B L F B

556-64-9 M e t h y

l t

h i o c y a n a t e 130. 00 ND ND ND ND ND

75-79-6 M e t h y

l t

r i c h l o r o s i l a n e 66. 40 1. 2 1

. 4 1. 7 2

. 0 2. 4

A

p r i l 15, 1999 B - 8

### E x hibit B

- 4 (c ontinue d)

CAS

Num b e r Che m i c al Nam e P o i n t ( C ) B o ilin g

o T emp era t u re C o rrect ion F a ct or ( T C F )

30 C o (86 F ) o 35 C (95 F ) o

o 40 C (104 F ) o

o 45 C (113 F ) o

o 50 C (122 F ) o

o

13463-39-3 N i c k e l c a r bo n y l 42. 85 ND ND ND ND ND

7697-37-2 N i t r i c a c i d 83. 00 1. 3 1

. 6 2. 0 2

. 5 3. 1

79-21-0 P e r a c e t i c a c i d 109. 85 1. 3 1

. 8 2. 3 3

. 0 3. 8

594-42-3 P e r c h l o ro m e t h y

l m e rc a p t a n 147. 00 ND ND ND ND ND

10025-87-3 P h o s ph o r u s o x y c h l o ri d e 105. 50 1. 3 1

. 6 1. 9 2

. 4 2. 9

7719-12-2 P h o s ph o r u s t r i c h l o r i d e 76. 10 1. 2 1

. 5 1. 8 2

. 1 2. 5

110-89-4 P i p e r i d i n e 106. 40 1. 3 1

. 6 2. 0 2

. 4 3. 0

107-12-0 P ro pi o n i t r i l e 97. 35 1. 3 1

. 6 1. 9 2

. 3 2. 8

109-61-5 P ro py l c h l o ro f o rm a t e 112. 40 ND ND ND ND ND

75-55-8 P ro py l e n e i m i n e 60. 85 1. 2 1

. 5 1. 8 2

. 1 2. 5

75-56-9 P ro py l e n e o x i d e 33. 90 1. 2 L F B L F B L F B L F B

7446-11-9 S u l f u r t r i o x i d e 44. 75 1. 3 1

. 7 L F B L F B L F B

75-74-1 T e t ra m e t h y

l l e a d 110. 00 ND ND ND ND ND

509-14-8 T e t ra n i t r o m e t h a n e 125. 70 1. 3 1

. 7 2. 2 2

. 8 3. 5

7550-45-0 T i t a n i u m t e t r a c h l o ri d e 135. 85 1. 3 1

. 6 2. 0 2

. 6 3. 2

584-84-9 T o l u e n e 2, 4-d i i s o c y a n a t e 251. 00 1. 6 2

. 4 3. 6 5

. 3 7. 7

91-08-7 T o l u e n e 2, 6-d i i s o c y a n a t e 244. 85 ND ND ND ND ND

26471-62-5 T o l u e n e d i i s o c y a n a t e (u n s pe c i f i e d

is om er ) 250. 00 1. 6 2

. 4 3. 6 5

. 3 7. 7

75-77-4 T ri m e t h y

l c h l o ro s i l a n e 57. 60 1. 2 1

. 4 1. 7 2

. 0 2. 3

108-05-4 V i n y l acetate m onom er 7 2

. 5 0 1

. 2 1 .5 1

. 9 2 .3 2

. 7

No te s :

ND: No d a t a a v a i l a bl e

. L

F B: Ch em ical ab o v e b o ilin g p o in t at th is tem p er atu r e; u s e L F B f o r an aly s is

.

A

p r i l 15, 1999 B - 9Ap p e ndix B

To x i c S u b s tan ces



### B

. 2 M ix tur e s C o ntaining T o x i c L i quids

I n c a s e of a s p ill of a liq uid m i x t u r e c ont a ining a r e gula t e d t o x i c s u bsta n c e ( w i t h th e e x c e pt ion of

c o m m on w a t e r s olut ions , dis c u s s e d in S e c t ion 3

. 3 in t h e t e x t ) , t h e a r e a of t h e p ool f o r m e d b y t h e e n t i r e liq uid

s p ill is de t e r m ine d a s de s c r i b e d in S e c t ion 3

. 2

. 2 or 3

. 2

. 3

. F o r t h e a r e a de t e r m ina t ion, if t h e de ns it y of t h e

m

i x t u r e is unknow n, t h e de ns it y of t h e r e gula t e d s u bsta n c e i n th e m i xtu r e m a y be a ssu m e d a s th e d e n s i t y o f

th e e n ti r e m i xtu r e

.

I f

t h e p a r t ia l va p o r p r e s s u r e of t h e r e gula t e d s u bsta n c e i n th e m i xtu r e i s know n, t h a t va p o r p r e s s u r e

m a y b e us e d t o de r ive a r e le a s e r a t e us ing t h e e q ua t ions in S e c t ion 3

. 2

. I f t h e p a r t ia l va p o r p r e s s u r e of t h e

r e gula t e d t o x i c s u bsta n c e i n th e m i xtu r e i s unknow n, it m a y b e e s t i m a t e d f r o m t h e va p o r p r e s s u r e of t h e p u r e

su bsta n c e ( l i ste d i n E x h i b i t B

- 2

, A ppe ndix B ) a nd t h e c onc e n t r a t ion in t h e m i x t u r e , if y ou a s s u m e t h e m i x t u r e is a n ide a l s olut ion, w h e r e a n ide a l s olut ion is one in w hic h t h e r e is c o m p le t e unif or m i t y of c ohe s ive f

o r c e s

. T his m e t hod m a y ove r e s t i m a t e or unde r e s t i m a t e t h e p a r t ia l p r e s s u r e f

o r

a r e gula t e d s u bsta n c e th a t i n t e r a c ts

w i t h t h e ot he r c o m p one nt s of a m i x t u r e or s olut ion. F o r e x a m p l e , w a t e r s olut ions a r e ge ne r a lly not ide a l

. T his m e t hod is like ly t o ove r e s t i m a t e t h e p a r t ia l p r e s s u r e of r e gula t e d s u bsta n c e s i n w a te r s olut ion if t h e r e is hy dr oge n b onding in t h e s olut ion ( e .g., s olut ions of a c ids or a l c ohols in w a t e r )

.

T o e s t i m a t e p a r t ia l p r e s s u r e f

o r

a r e gula t e d s u bsta n c e i n a m i xtu r e o r s olut ion, us e t h e f

ollow ing

s t e p s , b a s e d on R a oult ' s La w f

o r

ide a l s olut ions :

� D e t e rm i n e t h e m o l e frac t ion of t h e r e gula t e d s u bsta n c e i n th e m i xtu r e

.

-- T h e m o l e frac t ion of t h e r e gula t e d s u bsta n c e i n th e m i xtu r e i s th e n u m be r o f m o l e s of

t h e r e gula t e d s u bsta n c e i n th e m i xtu r e divide d b y t h e t o t a l num b e r of m ole s of a l l

su bsta n c e s i n th e m i xtu r e

.

- - I f t h e m ola r c onc e n t r a t ion ( m ole s p e r lit e r ) of e a c h c o m p one nt of t h e m i x t u r e is

know n, t h e m ole frac t ion m a y b e de t e r m ine d a s f ollow s :



### M × V X � r t

r n 

### (B -1 ) � M i 

### × V
t i � 1

or

( c a n c e ling out V ) : t



### M X � r

r n 

### (B -2 ) � M i i � 1

A

p r i l 15, 1999 B - 1 0Ap p e ndix B

To x i c S u b s tan ces

w h e r e : X

r = Mo l e frac t ion of r e gula t e d s u bsta n c e i n m i xtu r e ( unit le s s )

M

r = M ola r c onc e n t r a t ion of r e gula t e d s u bsta n c e i n m i xtu r e ( m o l e s pe r l i t e r )

V t = T o t a l volum e of m i x t u r e ( lit e r s )

n = Num b e r of c o m p one nt s of m i x t u r e
M i = M ola r c onc e n t r a t ion of e a c h c o m p one nt of m i x t u r e ( m ole s p e r lit e r )

F o r a m i x t u r e w i t h t h r e e c o m p one nt s , t his w ould c o r r e s p ond t o :



### M X

r 

### � r 

### (B -3 ) M � M � M

r 2 3

w h e r e : X

r = Mo l e frac t ion of r e gula t e d s u bsta n c e i n m i xtu r e ( unit le s s )

M

r = M ola r c onc e n t r a t ion of r e gula t e d s u bsta n c e ( f i r st c o m p o n e n t ) i n m i xtu r e ( m ole s p e r lit e r )

M 2 = M ola r c onc e n t r a t ion of s e c ond c o m p one nt of m i x t u r e ( m ole s p e r lit e r )

M 3 = M ola r c onc e n t r a t ion of a n y ot he r c o m p one nt s of m i x t u r e ( m ole s p e r lit e r )

- - I f t h e w e ight of e a c h of t h e c o m p one nt s of t h e m i x t u r e is know n, t h e m ole frac t i o n of

t h e r e gula t e d s u bsta n c e i n th e m i xtu r e m a y be c a l c u l a te d a s f ollow s :



### W

r 

### MW

r 

### X � (B -4 )

r n 

### W i 

### �
MW i i � 1

w h e r e : X

r = Mo l e frac t ion of t h e r e gula t e d s u bsta n c e W

r = We ight of t h e r e gula t e d s u bsta n c e
M W

r = M ole c ula r w e ight of t h e r e gula t e d s u bsta n c e

n = Num b e r of c o m p one nt s of t h e m i x t u r e W i = We ight of e a c h c o m p one nt of t h e m i x t u r e
M W i = M ole c ula r w e ight of e a c h c o m p one nt of t h e m i x t u r e

( Not e : We ight s c a n b e in a n y c ons is t e nt unit s

. )

F o r a m i x t u r e w i t h t h r e e c o m p one nt s , t his c o r r e s p onds t o :



### W

r 

### MW

r 

### X � (B -5 )

r 

### W W 2 

### W 3 r 

### � � MW MW MW

r 2 3

A

p r i l 15, 1999 B - 1 1Ap p e ndix B

To x i c S u b s tan ces

w h er e: X

r = M o l e frac t ion of t h e r e gula t e d s u bsta n c e W

r = W e ight of t h e r e gula t e d s u bsta n c e ( f i r st c o m p o n e n t o f th e m i xtu r e )

MW

r = M ole c ula r w e ight of t h e r e gula t e d s u bsta n c e W

2 = W e ight of t h e s e c ond c o m p one nt of t h e m i x t u r e MW 2 = M ole c ula r w e ight of t h e s e c ond c o m p one nt of t h e m i x t u r e W 3 = We ight of t h e t hir d c o m p one nt of t h e m i x t u r e
M W 3 = M ole c ula r w e ight of t h e t hir d c o m p one nt of t h e m i x t u r e

( Not e : We ight s c a n b e in a n y c ons is t e nt unit s

. )

� Es t i m a t e t h e p a r t ia l va p o r p r e s s u r e of t h e r e gula t e d s u bsta n c e i n th e m i xtu r e a s f ollow s :



### VP

m 

### � X

r 

### × VP
p 

### (B -6 )

w h e r e : V P

m = Part i a l v a p o r p r e s s u re o f t h e re gula t e d s u bsta n c e i n th e m i xtu r e ( m illim e t e r s

o f

mer cu r y ( mm H g ) )

X

r = Mo l e frac t ion of t h e r e gula t e d s u bsta n c e ( unit le s s )

VP = V a p or p r e s s u r e of t h e r e gula t e d s u bsta n c e i n pu r e f

o r m a t th e sa m e p

o t e m p e r a t ur e a s t h e m i x t u r e ( m m

Hg) ( v a p or p r e s s u r e a t 2 5 C is give n in

Ex hib it B

- 1 , Ap p e ndix B )

T h e e v a p or a t ion r a t e f

o r

t h e r e gula t e d s u bsta n c e i n th e m i xtu r e i s d e te r m i n e d a s f o r

pu r e su bsta n c e s ,

w i t h VP

m a s t h e va p o r p r e s s u r e

. I f t h e m i x t u r e c ont a ins m o r e t h a n one r e gula t e d t o x i c s u bsta n c e , c arry o u t

t h e a n a l y s is individua lly f

o r

e a c h of t h e r e gula t e d c o m p one nt s

. T h e r e le a s e r a t e e q ua t ion is :



### 0. 0035 × U 0. 78 

### × MW 2/ 3 

### × A × VP

� QR (B -7 ) T

w h e r e : Q R = Eva p o r a t ion r a t e ( p ounds p e r m inut e )

U = Wind s p e e d ( m e t e r s p e r s e c ond)

M W = M ole c ula r w e ight ( give n in Ex hib it B

- 2 , Ap p e ndix B )

A = S u r f a c e a r e a of p ool f o r m e d b y t h e e n t i r e q u a n t i t y of t h e m i x t u r e ( s q u a r e f e e t ) ( d e t e r m ine d a s de s c r i b e d in 3

. 2

. 2 )

VP = V a p or p r e s s u r e ( m m

Hg) ( V P

m f

r o m Eq ua t ion B

- 4 a b ove )

o o T = T e m p e r a t ur e ( K e lvin ( K ) ; t e m p e r a t ur e in C p lus 273, o r 298 f o r

25 C )

S e e Ap p e ndix D, S e c t ion D.2

. 1 f o r

m o r e dis c u s s ion of t h e e v a p or a t ion r a t e e q ua t ion. Eq ua t ion B

- 7

is de r ive d f r o m Eq ua t ion D- 1

.

Wor s t

- c a s e c ons e q ue nc e dis t a nc e s t o t h e t o x i c e ndp oint m a y b e e s t i m a t e d f r o m t h e r e le a s e r a t e us ing

t h e t a b l e s a nd ins t r uc t ions p r e s e n t e d in C h a p t e r 4

.

A

p r i l 15, 1999 B - 1 2

## AP P E NDI X C

F L AM M A BLE S U BS TANCES

A

p r i l 15, 1999

## AP P E NDIX C F LAM M A BLE S U BS TANCES

C. 1 E quat i on f o r E s t i m a t i on of Dis t ance t o 1 ps i Over pr es s u r e f o r Vapor Cl oud

E x pl os ions

F o r a w o r s t

- c a s e r e le a s e of f

l a m m a b l e ga s e s a nd vola t ile f

l a m m a b l e liq uids , t h e r e le a s e r a t e is not

c o n s i d e r e d

. Th e to ta l qu a n ti ty o f th e f

l a m m a bl e su bsta n c e i s a ssu m e d to f o r m a v a po r c loud. T h e e n t i r e

c ont e n t s of t h e c loud is a s s u m e d t o b e w i t hin t h e f

l a m m a b ilit y lim it s , a nd t h e c loud is a s s u m e d t o e x p lode

. F o r t h e w o r s t

- c a s e , a n a l y s is , 1 0 p e r c e n t of t h e f

l a m m a b l e va p o r in t h e c loud is a s s u m e d t o p a r t ic ip a t e in t h e

e x p los ion ( i .e ., t h e y i e ld f a c t o r is 0

. 1 0 )

. C ons e q ue nc e dis t a nc e s t o a n ove r p r e s s u r e le ve l of 1 p ound p e r

s q u a r e inc h ( p s i ) m a y b e de t e r m ine d us ing t h e f

ollow ing e q ua t ion, w hic h is b a s e d on t h e T N T

- e q uiva le nc y

m e t hod:

1/ 3 

### HC f 

### D � 17 × 0. 1 × W f 

### × (C -1 ) HC TN T

w h e r e : D = D i sta n c e to o v e r p r e ssu r e o f 1 psi ( m e t e r s)

W f = We ight of f

l a m m a b l e s u bsta n c e ( kilogr a m s or p ound s/2. 2)

Hc f = H e a t of c o m b us t ion of f

l a m m a b l e s u bsta n c e ( kilojoule s p e r kilogr a m ) ( lis t e d in Ex hib it C

- 1 )

HC TNT = H e a t of e x p los ion of t r init r o t olue ne ( T NT ) ( 4

, 680 kilojoule s p e r kilogr a m )

Th e f

a c to r 17 i s a c o n sta n t f o r

d a m a g e s a sso c i a t e d w i th 1. 0 psi o v e r p r e ssu r e s. Th e f

a c to r 0. 1

r e p r e s e n t s a n e x p los ion e f f i c i e n c y of 1 0 p e r c e n t

. T o c onve r t dis t a nc e s f r o m m e t e r s t o m ile s , m ult ip ly by 0. 00062.

Alt e r na t ive ly , us e t h e f

ollow ing e q ua t ion f o r

q u a n t i t y in p ounds a nd dis t a nc e in m ile s :

1/ 3 

### HC f 

### D mi 

### � 0. 0081 × 0. 1 × W lb 

### × (C -2 ) HC TN T

w h e r e : D mi = D i sta n c e to o v e r p r e ssu r e o f 1 psi ( m i l e s)

W lb = We ight of f

l a m m a b l e s u bsta n c e ( p ounds )

T h e s e e q ua t ions w e r e us e d t o de r ive R e f e r e nc e T a b l e 1 3 f o r

w o r s t

- c a s e dis t a nc e s t o t h e ove r p r e s s u r e

e ndp oint ( 1 p s i ) f o r

va p o r c loud e x p los ions

.



### C

. 2 M ix tur e s of F l am m a bl e Subs tanc e s

F o r a m i xtu r e o f f

l a m m a bl e su bsta n c e s , y o u m a y e sti m a te th e h e a t o f c o m b u st ion of t h e m i x t u r e f

r o m

t h e he a t s of c o m b us t ion of t h e c o m p one nt s of t h e m i x t u r e us ing t h e e q ua t ion b e low a nd t h e n us e t h e e q ua t ion give n in t h e p r e vious s e c t ion of t his a p p e ndix t o de t e r m ine t h e va p o r c loud e x p los ion dis t a nc e

. T h e he a t of

c o m b us t ion of t h e m i x t u r e m a y b e e s t i m a t e d a s f ollow s :

A

p r i l 15, 1999Ap p e ndix C

F l am m a b l e S u b s tan ces



### W W HC

m 

### � x 

### × HC

x 

### � y 

### × HC
y 

### (C -3 ) W W

m m

w h e r e : HC

m = H e a t of c o m b us t ion of m i x t u r e ( kilojoule s p e r kilogr a m )

W

x = We ight of c o m p one nt "X" in m i x t u r e ( kilogr a m s or p ound s/2. 2)

W

m = T o t a l w e ight of m i x t u r e ( kilogr a m s or p ound s/2. 2)

HC

x = H e a t of c o m b us t ion of c o m p one nt "X" ( kilojoule s p e r kilogr a m )

W
y = We ight of c o m p one nt "Y" in m i x t u r e ( kilogr a m s or p ound s/2. 2)

HC
y = H e a t of c o m b us t ion of c o m p one nt "Y" ( kilojoule s p e r kilogr a m )

He a t s of c o m b us t ion f o r

r e gula t e d f l a m m a b l e s u bsta n c e s a r e l i ste d i n E x h i b i t C

- 1 i n th e n e xt se c t i o n ( S e c t ion C

. 3 ) of t his a p p e ndix

.



### C

. 3 D ata f o r F l am m a bl e Subs tanc e s

T h e e x hib it s in t his s e c t ion of Ap p e ndix C p r ovide t h e da t a ne e d e d t o c arry o u t t h e c a l c u l a t ions f o r

r e gula t e d f l a m m a b l e s u bsta n c e s u s ing t h e m e t hods p r e s e n t e d in t h e t e x t of t his guida nc e

. Ex hib it C

- 1

p r e s e n t s he a t of c o m b us t ion da t a f o r

a ll r e gula t e d f l a m m a b l e s u bsta n c e s , E x h i b i t C

- 2 pr e s e n ts a ddit iona l da t a f o r

f

l a m m a b l e ga s e s , a nd Ex hib it C

- 3 p r e s e n t s a ddit iona l da t a f o r

f

l a m m a b l e liq uids

. T h e he a t s of

c o m b us t ion in Ex hib it C

- 1 a nd t h e da t a us e d t o de ve lop t h e f

a c t o r s in Ex hib it s C

- 2 a nd C

- 3 a r e p r im a r ily

f r o m De s ign I n s t i t u t e f

o r

P h y s ic a l P r o p e r t y Da t a , Am e r ic a n I n s t i t u t e of C h e m i c a l Engine e r s , P h y sic al and

T

h e r m ody nam ic P rope rtie s of P ure C h e m ic als, D ata C o m pilation

. T h e de r iva t ion of t h e f

a c t o r s p r e s e n t e d

in Ex hib it s C

- 2 a nd C

- 3 is dis c u s s e d in Ap p e ndix D.

A

p r i l 15, 1999 C - 2

### E x hibit C

- 1

He ats of C o m bus tion f o r F l am m a bl e Subs tanc e s

CAS No

. C h e m i c a l Na m e S t a t e P h y s i ca l

at 25 C o Co m b u s t i o n Hea t o f

( k

j ou l e /k g)

75- 07- 0 A c e t a l d e h y d e Ga s 25, 072

74- 86- 2 A c e t y l e n e [ E th y n e ] Ga s 48, 222

598- 73- 2 B r o m o tr i f luor oe t h y l e n e [ E t h e n e , b r om ot r i f luor o- ] G a s 1

, 967

106- 99- 0 1

, 3

- B u ta d i e n e Ga s 44, 548

106- 97- 8 B u t a n e G a s 45, 719

25167- 67- 3 B u t e n e G a s 45, 200 *

590- 18- 1 2

- B u te n e

- c i s Ga s 45, 171

624- 64- 6 2

- B u te n e

- t r a n s [ 2

- B u te n e , ( E ) ] Ga s 45, 069

106- 98- 9 1

- B u te n e Ga s 45, 292

107- 01- 7 2

- B u te n e Ga s 45, 100 *

463- 58- 1 Carb o n o x y s u l f i d e [Carb o n o x i d e s u l f i d e (CO S)] G a s 9

, 126

7791- 21- 1 C hlor ine m onox ide [ C hlor ine ox ide ] G a s 1

, 0 1 1 *

590- 21- 6 1

- C hlor op r o p y le ne [ 1 -Pro p e n e , 1

- c hlor o- ] Liq uid 2 3

, 0 0 0 *

557- 98- 2 2

- C hlor op r o p y le ne [ 1 -Pro p e n e , 2

- c hlor o- ] G a s 2 2

, 999

460- 19- 5 C y a noge n [ E t h a n e dinit r ile ] G a s 2 1

, 064

75- 19- 4 C y c l o p r o pa n e Ga s 46, 560

4109- 96- 0 D i c hlor os ila ne [ S ila ne , dic hlor o- ] G a s 8

, 225

7 5

- 3 7

- 6 Dif luor oe t h a n e [ E t h a n e , 1

, 1

- dif luor o- ] G a s 1 1

, 484

124- 40- 3 D i m e t h y l a m i n e [ M e th a n a m i n e , N

- m e t h y l

- ] G a s 35, 813

463- 82- 1 2

, 2

- D i m e t h y l p r o pa n e [Pro p a n e , 2

, 2

- d i m e t h y l

- ] G as 4 5

, 051

74- 84- 0 E th a n e G a s 47, 509

107- 00- 6 E th y l a c e t y l e n e [ 1

- B u ty n e ] G a s 45, 565

75- 04- 7 E th y l a m i n e [ E th a n a m i n e ] G a s 35, 210

7 5

- 0 0

- 3 E t h y l c hlor ide [ E t h a n e , c hlor o- ] G a s 1 9

, 917

74- 85- 1 E th y l e n e [ E th e n e ] Ga s 47, 145

A

p r i l 15, 1999 C - 3

### E x hibit C

- 1 (c ontinue d)

CAS No

. C h e m i c a l Na m e S t a t e P h y s i ca l

at 25 C o Co m b u s t i o n Hea t o f

( k

j ou l e /k g)

60- 29- 7 E th y l e t h e r [ E th a n e , 1, 1'

- o xy bi s- ] L i q u i d 33, 775

7 5

- 0 8

- 1 E t h y l m e r c a p t a n [ E t h a n e t hiol] Liq uid 2 7

, 948

109- 95- 5 E th y l n i t r i te [ N i t r o u s a c i d

, e t h y l e ste r ] Ga s 18, 000

1333- 74- 0 H y d r o g e n G a s 119, 950

7 5

- 2 8

- 5 I s o b u t a n e [Pro p a n e , 2

- m e t h y l ] G a s 4 5

, 576

78- 78- 4 I so pe n t a n e [ B u ta n e , 2- m e t h y l

- ] L i q u i d 44, 911

78- 79- 5 I so pr e n e [ 1

, 3

- B u ta d i e n e , 2- m e t h y l

- ] L i q u i d 43, 809

7 5

- 3 1

- 0 I s o p r o p y l am i n e [2 -Pro p a n a m i n e ] L i q u i d 3 6

, 484

7 5

- 2 9

- 6 I s o p r op y l c hlor ide [Pro p a n e , 2

- c hlor o- ] Liq uid 2 3

, 720

74- 82- 8 M e t h a n e Ga s 50, 029

74- 89- 5 M e t h y l a m i n e [ M e th a n a m i n e ] G a s 31, 396

563- 45- 1 3

- M e th y l

- 1

- b u t e n e G a s 44, 559

563- 46- 2 2

- M e th y l

- 1

- b u t e n e L i q u i d 44, 414

115- 10- 6 M e t h y l e t h e r [ M e th a n e , o x y b i s

- ] Ga s 28, 835

107- 31- 3 M e t h y l f o r m a t e [ F o r m i c a c i d

, m e t h y l e ste r ] L i q u i d 15, 335

115- 11- 7 2

- M e th y l pr o p e n e [ 1 -Pro p e n e , 2

- m e t h y l

- ] G as 4 4

, 985

504- 60- 9 1

, 3

- P e n t a d i e n e L i q u i d 43, 834

109- 66- 0 P e n ta n e L i q u i d 44, 697

109- 67- 1 1

- P e n t e n e L i q u i d 44, 625

646- 04- 8 2

- P e n t e n e , ( E )

- L i q u i d 44, 458

627- 20- 3 2

- P e n t e n e , ( Z )

- L i q u i d 44, 520

463- 49- 0 P r o pa d i e n e [ 1

, 2 -Pro p a d i e n e ] G as 4 6

, 332

74- 98- 6 P r o pa n e Ga s 46, 333

115- 07- 1 P r o py l e n e [ 1 -Pro p e n e ] G as 4 5

, 762

7 4

- 9 9

- 7 Pro p y n e [1 -Pro p y n e ] G as 4 6

, 165

7803- 62- 5 S i l a n e Ga s 44, 307

A

p r i l 15, 1999 C - 4

### E x hibit C

- 1 (c ontinue d)

CAS No

. C h e m i c a l Na m e S t a t e P h y s i ca l

at 25 C o Co m b u s t i o n Hea t o f

( k

j ou l e /k g)

116- 14- 3 T e t r a f luor oe t h y l e n e [ E t h e n e , t e t r a f luor o- ] G a s 1

, 284

75- 76- 3 T e t r a m e t h y l s i l a n e [ S i l a n e , te tr a m e t h y l

- ] L i q u i d 41, 712

10025- 78- 2 T r i c hlor os ila ne [ S ila ne , t r ic hlor o- ] Liq uid 3

, 754

7 9

- 3 8

- 9 T r i f luor oc hlor oe t h y l e n e [ E t h e n e , c hlor ot r i f luor o- ] G a s 1

, 837

75- 50- 3 T r i m e t h y l a m i n e [ M e th a n a m i n e , N

, N

- d i m e t h y l

- ] G a s 37, 978

689- 97- 4 Viny l a c e t y l e n e [ 1

- B u t e n- 3

- y n e ] G a s 4 5

, 357

7 5

- 0 1

- 4 Viny l c hlor ide [ E t h e n e , c hlor o- ] G a s 1 8

, 848

109- 92- 2 Viny l e t hy l e t he r [ E t h e n e , e t hox y

- ] Liq uid 3 2

, 909

7 5

- 0 2

- 5 Viny l f luor ide [ E t h e n e , f luor o- ] G a s 2

, 195

7 5

- 3 5

- 4 Viny lide ne c hlor ide [ E t h e n e , 1

, 1

- dic hlor o- ] Liq uid 1 0

, 354

7 5

- 3 8

- 7 Viny lide ne f

luor ide [ E t h e n e , 1

, 1

- dif luor o- ] G a s 1 0

, 807

107- 25- 5 Viny l m e t hy l e t he r [ E t h e n e , m e t hox y

- ] G a s 3 0

, 549

* Es tim ated h eat o f co m b u s tio n

A

p r i l 15, 1999 C - 5Exhibit C-2DataforFlammableGasesCASMolecularSpecificRatioofLimits(Vol%)FlammabilityLFL(mg/L)Factor(GF)GasgFactorBoilingLiquid(LFB)Factor(Boiling)Density(DF)ReferenceTableaFactor(PFF)PoolFireFractionFactorFlash(FFF)fNumberChemicalNameWeightHeatsLower(LFL)UpperUFL75-07-0Acetaldehyde44.051.184.060.072220.110.62Dense2.70.01874-86-2Acetylene26.041.232.580.027170.120.78Buoyantb4.80.23f598-73-2Bromotrifluoroethylene160.921.11c37.0c41c0.25c0.29cDense0.42c0.15c106-99-01,3-Butadiene54.091.122.011.544240.140.75Dense5.50.15106-97-8Butane58.121.091.59.036250.140.81Dense5.90.1525167-67-3Butene56.111.101.79.539240.140.77Dense5.60.14590-18-12-Butene-cis56.111.121.69.737240.140.76Dense5.60.11624-64-62-Butene-trans56.111.111.89.741240.140.77Dense5.60.12106-98-91-Butene56.111.111.69.337240.140.78Dense5.70.17107-01-72-Butene56.111.101.79.739240.140.77Dense5.60.12463-58-1Carbon oxysulfide60.081.2512.029.0290260.180.41Dense1.30.297791-21-1Chlorinemonoxide86.911.2123.5NA830310.19NADense0.15NA557-98-22-Chloropropylene76.531.124.516.0140290.160.54Dense3.30.011460-19-5Cyanogen52.041.176.032.0130240.150.51Dense2.50.4075-19-4Cyclopropane42.081.182.410.441220.130.72Dense5.40.234109-96-0Dichlorosilane101.011.164.096.0160330.200.40Dense1.30.08475-37-6Difluoroethane66.051.143.718.0100270.170.48Dense1.60.23124-40-3Dimethylamine45.081.142.814.452220.120.73Dense3.70.090463-82-12,2-Dimethylpropane72.151.071.47.541270.160.80Dense6.40.1174-84-0Ethane30.071.192.913.036180.140.89Dense5.40.75107-00-6Ethylacetylene54.091.112.032.944240.130.73Dense5.40.09175-04-7Ethylamine45.081.133.514.064220.120.71Dense3.60.040April15,1999C -6Exhibit C-2 (continued)CASMolecularSpecificRatioofLimits(Vol%)FlammabilityLFL(mg/L)Factor(GF)GasgFactorBoilingLiquid(LFB)Factor(Boiling)Density(DF)ReferenceTableaFactor(PFF)PoolFireFractionFactorFlash(FFF)fNumberChemicalNameWeightHeatsLower(LFL)UpperUFL75-00-3Ethylchloride64.511.153.815.4100270.150.53Dense2.60.05374-85-1Ethylene28.051.242.736.031180.140.85Buoyantb5.40.63f109-95-5Ethylnitrite75.071.304.050.0120300.160.54Dense2.0NA1333-74-0Hydrogen2.021.414.075.03.35.0eedeNA75-28-5Isobutane58.121.091.88.443250.150.82Dense6.00.2374-82-8Methane16.041.305.015.033140.151.1Buoyant5.60.87f74-89-5Methylamine31.061.194.920.762190.100.70Dense2.70.12563-45-13-Methyl-1-butene70.131.081.59.143260.150.77Dense6.00.030115-10-6Methylether46.071.153.327.364220.140.66Dense3.40.22115-11-72-Methylpropene56.111.101.88.841240.140.77Dense5.70.18463-49-0Propadiene40.071.162.12.134210.130.73Dense5.20.2074-98-6Propane44.101.132.09.536220.140.83Dense5.70.38115-07-1Propylene42.081.152.011.034210.140.79Dense5.50.3574-99-7Propyne40.071.161.739.928210.120.72Dense4.90.187803-62-5Silane32.121.24ccc19ceeDensee0.41f116-14-3Tetrafluoroethylene100.021.1211.060.0450330.290.32Dense0.250.6979-38-9Trifluorochloroethylene116.471.118.438.7400350.260.33Dense0.340.2775-50-3Trimethylamine59.111.102.011.648250.140.74Dense4.80.12689-97-4Vinylacetylene52.081.132.231.747240.130.69Dense5.40.08675-01-4Vinylchloride62.501.183.633.092260.160.50Dense2.40.1475-02-5Vinylfluoride46.041.202.621.749230.170.57Dense0.280.3775-38-7Vinylidenefluoride64.041.165.521.3140270.220.42Dense1.80.50April15,1999C -7Exhibit C-2 (continued)CASMolecularSpecificRatioofLimits(Vol%)FlammabilityLFL(mg/L)Factor(GF)GasgFactorBoilingLiquid(LFB)Factor(Boiling)Density(DF)ReferenceTableaFactor(PFF)PoolFireFractionFactorFlash(FFF)fNumberChemicalNameWeightHeatsLower(LFL)UpperUFL107-25-5Vinylmethylether58.081.122.639.062250.170.57Dense3.70.093Notes:NA:Data not availablea"Buoyant"in the Reference Table columnrefersto the tablesforneutrallybuoyant gasesand vapors; "Dense"refersto the tablesfordensegasesand vapors.SeeAppendix D,Section D.4.4,formoreinformation on thechoiceofreferencetables.bGasesthatarelighterthanairmaybehaveasdensegasesupon releaseifliquefiedunderpressureorcold; considertheconditionsofreleasewhenchoosing theappropriate table.cReported to bespontaneouslycombustible.dMuchlighterthanair;table ofdistancesforneutrallybuoyant gasesnotappropriate.ePool formation unlikely.ofCalculatedat298 K(25C)withthefollowingexceptions:Acetylenefactorat250 KasreportedinTNO,MethodsfortheCalculation of thePhysicalEffectsof theEscapeof DangerousMaterial(1980).Ethylenefactorcalculatedatcriticaltemperature,282 K.Methanefactorcalculatedatcriticaltemperature,191 K.Silanefactorcalculatedatcriticaltemperature,270 K.gUseGFforgasleaksunderchoked (maximum)flow conditions.April15,1999C -8Exhibit C-3Data forFlammableLiquidsCASChemical NameMolecular(Vol%)FlammabilityLimit(mg/L)LFLLiquid FactorsFactorDensityFactor(LLF)LiquidLeakaTableReferencebFactor(PFF)PoolFireNumberWeightLower(LFL)Upper(UFL)Ambient(LFA)Boiling(LFB)590-21-61-Chloropropylene76.534.516.01400.110.150.5245Dense3.260-29-7Ethylether74.121.948.0570.110.150.6934Dense4.375-08-1Ethylmercaptan62.142.818.0710.100.130.5840Dense3.378-78-4Isopentane72.151.47.6410.140.150.7930Dense6.178-79-5Isoprene68.122.09.0560.110.140.7232Dense5.575-31-0Isopropylamine59.112.010.4480.100.130.7133Dense4.175-29-6Isopropylchloride78.542.810.7900.110.160.5741Dense3.1563-46-22-Methyl-1-butene70.131.49.6400.120.150.7531Dense5.8107-31-3Methylformate60.055.920.01400.100.130.5046Dense1.8504-60-91,3-Pentadiene68.121.613.1440.0770.140.7233Dense5.3109-66-0Pentane72.151.38.0380.100.150.7830Dense5.8109-67-11-Pentene70.131.58.7430.130.150.7731Dense5.8646-04-82-Pentene,(E)-70.131.410.6400.100.150.7631Dense5.6627-20-32-Pentene,(Z)-70.131.410.6400.100.150.7531Dense5.675-76-3Tetramethylsilane88.231.5NA540.170.170.5940Dense6.310025-78-2Trichlorosilane135.451.290.5660.180.230.3764Dense0.68109-92-2Vinylethylether72.111.728.0500.100.150.6536Dense4.275-35-4Vinylidenechloride96.947.3NA2900.150.180.4454Dense1.6Notes:NA:Data not available.aUse the LLFonlyforleaksfromtanksat atmospheric pressure.b"Dense"inthe Reference Table columnreferstothe tablesfordense gasesandvapors.See AppendixD,SectionD.4.4,formoreinformation on thechoiceofreference tables.April15,1999C -9

## AP P E NDI X D

TECHNI CAL BACKGROUND

A

p r i l 15, 1999

## AP P E NDI X D TECHNI CAL BACKGROUND

D. 1 Wor s t

- C as e Rel e as e Rat e f o r Gas e s

D. 1. 1 U nm it igat ed Rel e as e

T h e a s s u m p t ion t h a t t h e t o t a l q u a n t i t y of t o x i c ga s is r e le a s e d in 1 0 m inut e s is t h e s a m e a s s u m p t ion

us e d in EP A' s T e c hnic al G uidanc e for H azards A naly sis ( 1987)

.



### D

. 1. 2 G as e o us R e l e as e I n s i de B u il ding

T h e m i t iga t ion f a c t o r f

o r

ga s e ous r e le a s e ins ide a b uilding is b a s e d on a doc um e n t e n t i t l e d

, R isk

M

itigation in L and U s e P lanning: I ndoor R e le ase s of T o x i c G ase s , by S

. R

. P o r t e r

. Th i s pa pe r pr e s e n te d

t h r e e r e le a s e s c e n a r ios a nd dis c u s s e d t h e m i t iga t ing e f f e c t s t h a t w ould oc c u r in a b uilding w i t h a volum e of 1, 000 c u bi c m e t e r s a t th r e e d i f f e r e n t b uilding a i r e x c h a nge r a t e s

. T h e r e is a c onc e r n t h a t a b uilding m a y not
b e a b le t o w i t h s t a nd t h e p r e s s u r e s of a ve r y la r g e r e le a s e

. How e v e r , t his p a p e r indic a t e d t h a t r e le a s e r a t e s of

a t l e a st 2, 000 p ounds p e r m inut e c ould b e w i t h s t ood b y a b uilding.

Ana ly z ing t h e da t a in t his p a p e r s e ve r a l w a y s , t h e va lue of 5 5 p e r c e n t emer g e d a s r e p r es en t ing t h e

m

i t iga t ion t h a t c ould oc c u r f

o r

a r e le a s e s c e n a r io int o a b uilding. Da t a a r e p r ovide d on t h e m a x i m u m r e le a s e

r a t e in a b uilding a nd t h e m a x i m u m r e le a s e r a t e f

r o m a b uilding. M a king t his dir e c t c o m p a r i s on a t t h e low e r

m a x i m u m r e le a s e r a t e ( 3 .3 6 kg/ s ) ga ve a r e le a s e r a t e f

r o m t h e b uilding of 5 5 p e r c e n t of t h e r e le a s e r a t e int o

t h e b uilding. Us ing inf or m a t ion p r ovide d on a not he r m a x i m u m r e le a s e r a t e ( 1 0

. 9 kg/ m in) a nd a c c ount ing f o r

t h e t i m e f

o r

t h e r e le a s e t o a c c u m ula t e in t h e b uilding, a p p r ox im a t e l y 5 5 p e r c e n t emer g e d a g a i n

.

T h e c hoic e of b uilding ve nt ila t ion r a t e s a f f e c t s t h e r e s ult s

. T h e p a p e r p r e s e n t e d m i t iga t ion f o r

t h r e e dif f e r e nt ve nt ila t ion r a t e s , 0

. 5

, 3

, a nd 1 0 a i r c h a nge s p e r hour

. A ve nt ila t ion r a t e of 0

. 5 c h a nge s p e r hour is

r e p r e s e n t a t ive of s p e c i a lly de s igne d, “ g a s

- t ight ” b uildings , b a s e d on t h e P o r t e r r e f e r e nc e

. EP A de c ide d t h a t

t his ve nt ila t ion r a t e w a s a p p r op r i a t e f

o r

t his a n a l y s is

. A m i t iga t ion f a c t o r of 5 5 p e r c e n t m a y b e us e d in t h e

e v e n t of a ga s e ous r e le a s e w hic h doe s not de s t r oy t h e b uilding int o w hic h it is r e le a s e d

. T his f a c t o r m a y

ove r s t a t e t h e m i t iga t ion p r ovide d b y a b uilding w i t h a highe r ve nt ila t ion r a t e

.

F o r r e le a s e s of a m m onia , c hlor ine , a nd s ulf ur

diox ide , f a c t o r s s p e c i f i c t o t h e c h e m i c a ls , t h e

c ondit ions of t h e r e le a s e , a nd b uilding ve nt ila t ion r a t e s ha ve b e e n de ve lop e d t o e s t i m a t e m i t iga t ion of r e le a s e s in b uildings

. F o r inf or m a t ion on t h e s e f

a c t o r s a nd e s t i m a t ion of m i t iga t e d r e le a s e r a t e s , s e e B a cku p
I nform ation for the H azard A sse ssm e nts in the R M

P

O

ffsite C onse que nc e A naly sis G uidanc e , the

G uidanc e for W aste w ate r T r e atm e nt F a c ilitie s and the G uidanc e for A m m onia R e frige ration - A nhy drous

A m m onia, A que ous A m m onia, C hlorine and Sulfur D iox ide

. S e e a l s o t h e indus t r y

- s p e c i f i c guida nc e doc um e n t s f o r

a m m onia r e f r ige r a t ion a nd P O T W s

.



### D. 2 Wor s t

- C as e Rel e as e Rat e f o r L i quids

D. 2. 1 E vapor at ion Rat e E quat i on

T h e e q ua t ion f o r

e s t i m a t ing t h e e v a p or a t ion r a t e of a liq uid f r o m a p ool is f r o m t h e T e c hnic al

G uidanc e for H azards A naly sis , Ap p e ndix G

. T h e s a m e a s s u m p t ions a r e m a de f

o r

de t e r m ina t ion of

A

p r i l 15, 1999Ap p e ndix D

T e c hnic a l Ba c kgr ound

m a x i m u m p ool a r e a ( i .e ., t h e p ool is a s s u m e d t o b e 1 c e n t i m e t e r ( 0

. 033 f e e t ) d e e p )

. Th e e v a p o r a t ion r a t e

e q ua t ion ha s b e e n m odif ie d t o inc lude a dif f e r e nt m a s s t r a n s f e r

c o e f f i c i e n t f o r

w a t e r , t h e r e f e r e nc e c o m p ound.

F o r t his doc um e n t

, a va lue of 0

. 6 7 c e n t i m e t e r s p e r s e c ond is us e d a s t h e m a s s t r a n s f e r

c o e f f i c i e n t

, ins t e a d of

t h e va lue of 0

. 2 4 c i t e d in t h e T e c hnic al G uidanc e for H azards A naly sis

. T h e va lue of 0

. 6 7 is b a s e d on

Dona ld M a c K a y a nd R ona ld S

. M a t s ugu, "Eva p o r a t ion R a t e s of Liq uid Hy dr oc a r b on S p ills on La nd a n d

Wa t e r , " C anadian J ournal of C h e m ic al E ngine e ring , Augus t 1973, p. 434. Th e e v a p o r a t ion e q ua t ion

b eco mes :



### 0. 284 × U 0. 78 

### × MW 2/ 3 

### × A × VP

� QR (D -1 ) 82. 05 × T

w h er e: QR = Eva p o r a t ion r a t e ( p ounds p e r m inut e )

U = Wind s p e e d ( m e t e r s p e r s e c ond)

MW = M ole c ula r w e ight ( give n in Ex hib it s B

- 1 a nd B

- 2 , Ap p e ndix B

, f o r

t o x i c

su bsta n c e s a n d E x h i b i ts C

- 2 a n d C

- 3

, A ppe ndix C

, f o r

f

l a m m a b l e

su bsta n c e s )

A = S ur f a c e a r e a of p ool f o r m e d b y t h e e n t i r e q u a n t i t y of t h e m i x t u r e ( s q u a r e f e e t ) ( d e t e r m ine d a s de s c r i b e d in S e c t ion 3

. 2

. 2 of t h e t e x t )

VP = V a p o r pr e ssu r e ( m m

H g )

o T = T e m p e r a t u r e o f r e l e a s e d su bsta n c e ( K e lvin ( K ) ; t e m p e r a t ur e in C p lus 273,

o o r

298 f o r

25 C )



### D. 2. 2 F act o r s f o r E vapor at ion Rat e E s t i m a t e s

Liq uid F a c t o r s

. T h e liq uid f a c t o r s , Liq uid F a c t o r Am b i e n t ( L F A ) a nd Liq uid F a c t o r B oiling ( L FB),

us e d t o e s t i m a t e t h e e v a p or a t ion r a t e f

r o m a liq uid p ool ( s e e S e c t ion 3

. 2 of t his guida nc e doc um e n t ) , a r e de r ive d a s de s c r i b e d in t h e T e c hnic al G uidanc e for H azards A naly sis , Ap p e ndix G

, w i t h t h e f

ollow ing

d i ffe re n c e s :

� Th e m a ss tr a n sf e r

c o e f f i c i e n t o f w a te r i s a ssu m e d to be 0. 67, a s d i s c u sse d a b o v e ; th e v a l u e of

t h e f

a c t o r t h a t inc lude s c onve r s ion f a c t o r s , t h e m a s s t r a n s f e r

c o e f f i c i e n t f o r

w a t e r , a nd t h e

m ole c ula r w e ight of w a t e r t o t h e one

- t hir d p o w e r , give n a s 0

. 106 i n th e T e c hnic al G uidanc e i s 0. 284 i n th i s guida nc e

.

� D e n s i t y o f a l l su bsta n c e s w a s a ssu m e d to be th e d e n s i t y o f w a te r i n th e T e c hnic al G uidanc e ;

t h e de ns it y w a s inc lude d in t h e liq uid f a c t o r s

. F o r t his guida nc e doc um e n t

, de ns it y is not
inc lude d in t h e LF A a nd LF B va lue s p r e s e n t e d in t h e t a b l e s ; ins t e a d , a s e p arat e D e n s i t y F a c t o r ( D F ) ( dis c u s s e d b e low ) is p r ovide d t o b e us e d in t h e e v a p or a t ion r a t e e s t i m a t ion.

Wit h t h e s e m odif ic a t ions , t h e LF A is :



### 0. 284 × MW 2/ 3 

### × VP LF A � (D -2 ) 82. 05 × 298

w h er e: MW = M ole c ula r w e ight

A

p r i l 15, 1999 D - 2Ap p e ndix D

T e c hnic a l Ba c kgr ound

VP = V ap o r p r e s s u re at am b i e n t t e m p e rat u r e (m m

H g )

o 298 K ( 25 C ) = A m bi e n t te m p e r a t u r e a n d te m p e r a t u r e o f r e l e a s e d su bsta n c e

L FB i s :



### 0. 284 × MW 2/ 3 

### × 760 LF B � (D -3 ) 82. 05 × BP

w h er e: MW = M ole c ula r w e ight

7 6 0 = V a p or p r e s s u r e a t b oiling t e m p e r a t ur e ( m m

Hg)

BP = B oiling p oint ( K )

LF A a nd LF B va lue s w e r e de ve lop e d f

o r

a ll t o x i c a nd f l a m m a b l e r e gula t e d liq uids , a nd LF B va lue s , t o b e us e d f

o r

a n a l y s is of ga s e s liq ue f i e d b y r e f r ige r a t ion, w e r e de ve lop e d f

o r

t o x i c a nd f l a m m a b l e ga s e s

.

De ns it y F a c t o r

. B e c a us e s o m e of t h e r e gula t e d liq uids ha ve de ns it ie s ve r y dif f e r e nt f r o m t h a t of

w a te r , th e d e n s i t y o f e a c h su bsta n c e w a s u s e d to d e v e l o p a D e n s i t y F a c to r ( D F ) f o r

th e d e te r m i n a t ion of

m a x i m u m p ool a r e a f o r

t h e e v a p or a t ion r a t e e s t i m a t ion. DF va lue s w e r e de ve lop e d f

o r

t o x i c a nd f l a m m a b l e liq uids a t a m b i e n t t e m p e r a t ur e a nd f o r

t o x i c a nd f l a m m a b l e ga s e s a t t h e i r b oiling p oint s

. T h e de ns it y f

a c t o r is :



### 1 DF � (D -4 ) d × 0

. 033

2 w h er e: DF = D e n si ty f

a c to r ( 1/( l bs/f t ) )

d = D e n s i t y o f th e su bsta n c e i n p ounds p e r c u b i c f oot
0

. 0 3 3 = D e p t h of p ool f o r

m a x i m u m a r e a ( f e e t )

T e m p e r a t ur e C o r r e c t ion F a c t o r s . T e m p e r a t ur e c o r r e c t ion f a c t o r s w e r e de ve lop e d f

o r

t o x i c liq uids

o r e l e a s ed a t t emp er a t u r es a b o v e 2 5 C

, t h e t emp er a t u r e u s ed f

o r

d e v e l o p men t o f t h e L F A s

. T h e t emp er a t u r e

c o r r e c t ion f a c t o r s a r e b a s e d on va p o r p r e s s u r e s c a lc ula t e d f r o m t h e c o e f f i c i e n t s p r ovide d in P h y sic al and

T

h e r m ody nam ic P rope rtie s of P ure C h e m ic als, D ata C o m pilation , de ve lop e d b y t h e De s ign I n s t i t u t e f

o r Ph y s i c al Pro p e rt y D a t a (D I PPR), A m e r i c an I n s t i t u t e o f Ch e m i c a l Engine e r s

. T h e f

a c t o r s a r e c a lc ula t e d a s f ollow s :



### VP T 

### × 298

� TC F T 

### VP 298 

### × T (D -5 )

w h er e: TCF T = T e m p e r a t ur e C o r r e c t ion F a c t o r a t t e m p e r a t ur e T

VP T = V ap o r p r e s s u re at t e m p e rat u r e T

VP 298 = V a p o r pr e ssu r e a t 298 K

T = T e m p e r a t u r e ( K ) o f r e l e a s e d su bsta n c e

o o F a c t o r s w e r e de ve lop e d a t int e r va ls of 5 C f o r

t e m p e r a t ur e s up t o 5 0 C

.

A

p r i l 15, 1999 D - 3Ap p e ndix D

T e c hnic a l Ba c kgr ound

No c o r r e c t ion f a c t o r w a s d eemed n eces s a r y f

o r

ch a n g e s i n t h e d e n s i t y o f t h e r e gula t e d t o x i c liq uids

w i t h c h a nge s in t e m p e r a t ur e , a l t hough t h e de ns it y c ould a f f e c t t h e p ool a r e a a nd r e le a s e r a t e e s t i m a t e s

. Ana ly s i s of t h e t e m p e r a t ur e de p e nde nc e of t h e de ns it y of t h e s e liq uids indic a t e d t h a t t h e c h a nge s in de ns it y

w i th te m p e r a t u r e w e r e v e r y sm a l l c o m p a r e d to th e c h a n g e s i n v a po r pr e ssu r e w i th te m p e r a t u r e

.



### D. 2. 3 C om m o n Wat er Sol u t i ons and Ol eum

Wa t e r s olut ions of r e gula t e d t o x i c s u bsta n c e s m u st be a n a l y z e d so m e w h a t d i f f e r e n t l y f

r o m pu r e to xi c liq uids

. Ex c e p t f o r

s olut ions of r e la t ive ly low c onc e n t r a t ion, t h e e v a p or a t ion r a t e va r i e s w i t h t h e

c onc e n t r a t ion of t h e s olut ion. At one s p e c i f i c c onc e n t r a t ion, t h e c o m p os it ion of t h e liq uid doe s not c h a nge a s

e v a p or a t ion oc c u r s

. F o r c onc e n t r a t e d s olut ions of vola t ile s u bsta n c e s , th e e v a p o r a t ion r a t e f

r o m a p ool m a y de c r e a s e , ve r y r a p idly in s o m e c a s e s , a s t h e t o x i c s u bsta n c e vola t iliz e s a nd it s c onc e n t r a t ion in t h e p ool

de c r e a s e s

. T o a n a l y z e t h e s e c h a nge s , EP A us e d s p r e a ds he e t s t o e s t i m a t e t h e va p o r p r e s s u r e , c onc e n t r a t ion,

a nd r e le a s e r a t e a t va r ious t i m e int e r va ls f o r

r e gula t e d t o x i c s u bsta n c e s i n w a te r s olut ion e v a p or a t ing f r o m

p ools

. I n a ddit ion t o t h e s p r e a ds he e t a n a l y s is , EP A us e d t h e ALO HA m ode l w i t h a n a ddit iona l s t e p

- f unc t ion

f e a t ur e ( not a v a ila b l e in t h e p u b lic ve r s ion)

. Wit h t his s t e p

- f unc t ion f e a t ur e , c h a nge s in t h e r e le a s e r a t e c ould

b e inc or p o r a t e d a nd t h e e f f e c t s of t h e s e c h a nge s on t h e c ons e q ue nc e dis t a nc e a n a l y z e d

. T h e r e s ult s of t h e

s p r e a ds he e t c a lc ula t ions a nd t h e m ode l w e r e f

ound t o b e in good a g r eemen t

. T h e d i s t a n ce r e s u l t s o b t a i n e d

f r o m t h e s p r e a ds he e t a n a l y s is a nd t h e m ode l f o r

va r ious s olut ions w e r e c o m p a r e d w i t h t h e r e s ult s f r o m

va r ious t i m e a v e r a g e s t o e x a m ine t h e s e ns it ivit y of t h e r e s ult s

. An a v e r a ging t i m e of 1 0 m inut e s w a s f ound t o give r e a s ona b l e a g r eemen t w i t h t h e s t e p

- f u n c t ion m ode l f o r

m o s t s u bsta n c e s a t v a r ious c onc e n t r a t ions

. T h e

s p r e a ds he e t a n a l y s is a l s o indic a t e d t h a t t h e f

i r s t 1 0 m inut e s of e v a p or a t ion w a s t h e m o s t im p o r t a n t

, a nd t h e

e v a p or a t ion r a t e in t h e f

i r s t 1 0 m inut e s like ly c ould b e us e d t o e s t i m a t e t h e dis t a nc e t o t h e e ndp oint

.

O l e u m is a s olut ion of s ulf ur

t r iox ide in s ulf ur ic a c id. S ulf ur

t r iox ide e v a p or a t ing f r o m ole um

e x h i b i t s re l e as e c h arac t e ri s t i c s s i m i l ar t o t h o s e o f t o x i c s u bsta n c e s e v a p o r a t ing f r o m w a t e r s olut ions

. A n a l y s i s o f o l e u m re l e as e s , t h e r e f o r e , w a s c arri e d o u t i n t h e s a m e w a y as fo r w a t e r s olut ions

.

NO AA de ve lop e d a c o m p ut e r iz e d c a lc ula t ion m e t hod t o e s t i m a t e p a r t ia l va p o r p r e s s u r e s a nd r e le a s e

r a t e s f o r

r e gula t e d t o x i c s u bsta n c e i n s olut ion a s a f unc t ion of c onc e n t r a t ion, b a s e d on va p o r p r e s s u r e da t a fro m P e rry 's C h e m ic al E ngine e rs' H andbook a nd ot he r s our c e s

. Us ing t his m e t hod a nd s p r e a ds he e t

c a lc ula t ions , EP A e s t i m a t e d p a r t ia l va p o r p r e s s u r e s a nd e v a p or a t ion r a t e s a t one

- m inut e int e r va ls ove r 1 0

m

inut e s f o r

s olut ions of va r ious c onc e n t r a t ions

. T h e 1 0

- m inut e t i m e p e r iod w a s c hos e n b a s e d on t h e ALO HA r e s ult s a nd ot he r c a lc ula t ions

. F o r e a c h one

- m inut e int e r va l, EP A e s t i m a t e d t h e c onc e n t r a t ion of t h e

s olut ion b a s e d on t h e q u a n t i t y e v a p or a t e d in t h e p r e vious int e r va l a nd e s t i m a t e d t h e p a r t ia l va p o r p r e s s u r e b a s e d on t h e c onc e n t r a t ion. T h e s e e s t i m a t e d va p o r p r e s s u r e s w e r e us e d t o c a lc ula t e a n a v e r a g e va p o r

p r e s s u r e ove r t h e 1 0

- m inut e p e r iod; t his a v e r a g e va p o r p r e s s u r e w a s us e d t o de r ive Liq uid F a c t o r Am b i e n t ( L F A ) va lue s , a s de s c r i b e d a b ove f

o r

liq uids

. Us e of t h e s e f

a c t o r s is int e nde d t o give a n e v a p or a t ion r a t e t h a t

a c c ount s f o r

t h e de c r e a s e in e v a p or a t ion r a t e e x p e c t e d t o t a ke p l a c e a s t h e s olut ion e v a p or a t e s

.

De ns it y F a c t o r s ( D F ) w e r e de ve lop e d f

o r

s olut ions of va r ious c onc e n t r a t ions f r o m da t a in P e rry 's

C

h e m ic al E ngine e rs' H andbook a nd ot he r s our c e s , a s dis c u s s e d a b ove f

o r

liq uids

.

B e c a us e s olut ions do not ha ve de f ine d b oiling p oint s , EP A did not de ve lop Liq uid F a c t o r B oiling (L FB) v a l u e s fo r s olut ions

. As a s i m p le a nd c ons e r va t ive a p p r oa c h , t h e q u a n t i t y of a r e gula t e d s u bsta n c e i n a

s olut ion a t a n e l e v a t e d t e m p e r a t ur e s is t r e a t e d a s a p u r e s u bsta n c e

. Th e L F B f o r

th e pu r e su bsta n c e , o r th e

A

p r i l 15, 1999 D - 4Ap p e ndix D

T e c hnic a l Ba c kgr ound

LF A a nd a t e m p e r a t ur e c o r r e c t ion f a c t o r , is us e d t o e s t i m a t e t h e init ia l e v a p or a t ion r a t e of t h e r e gula t e d

su bsta n c e f

r o m th e s olut ion. O nly t h e f

i r s t 1 0 m inut e s of e v a p or a t ion a r e c ons ide r e d, a s f o r

s olut ions a t

a m b i e n t t e m p e r a t ur e s , b e c a us e t h e r e le a s e r a t e w ould de c r e a s e r a p idly a s t h e s u bsta n c e e v a p o r a t e s a n d th e

c onc e n t r a t ion in t h e s olut ion de c r e a s e s

. T his a p p r oa c h w ill like ly give a n ove r e s t i m a t e of t h e r e le a s e r a t e a n d

of

t h e c ons e q ue nc e dis t a nc e

.



### D

. 2

. 4 R el ea ses In si d e B u i l d i n g s

I f

a liq uid is r e le a s e d ins ide a b uilding, it s r e le a s e t o t h e out s ide a i r w ill b e m i t iga t e d in t w o w a y s

. F i r s t

, t h e e v a p or a t ion r a t e of t h e liq uid m a y b e m u c h low e r ins ide a b uilding t h a n out s ide

. T his is due t o w ind

s p e e d , w hic h dir e c t ly a f f e c t s t h e e v a p or a t ion r a t e

. T h e s e c ond m i t iga t ing f a c t o r is t h a t t h e b uilding p r ovide s

r e s i s t a nc e t o dis c h a r g e of c ont a m ina t e d a i r t o t h e out door s

.

I n t his m e t hod, a c ons e r va t ive w ind s p e e d , U, of 0

. 1 m e t e r p e r s e c ond ( m / s ) w a s a s s u m e d in t h e b uilding. ( S e e e nd of t e x t f o r

a jus t i f i c a t ion of t his w ind s p e e d .) F o r a r e le a s e out door s in a w o r s t

- c a s e

s c e n a r io, U is s e t t o 1

. 5 m / s , a nd f o r

a n a l t e r n a t ive s c e n a r io, U is s e t t o 3 m / s

. T h e e v a p or a t ion r a t e e q ua t ion

is :



### � QR U 0. 78 

### × ( LF A

, LF B )× A (D -6 )

w h er e: QR = R e l e a s e r a t e ( p ounds p e r m inut e ( l bs/m i n ) )

U = Wind s p e e d ( m e t e r s p e r s e c ond ( m / s ) )

LF A = Liq uid F a c t o r Am b i e n t

LF B = Liq uid F a c t o r B oiling

2 A = A r e a of p ool ( s q u a r e f

e e t ( f t ) )

As c a n b e s e e n , if U ins ide a b uilding is only 0

. 1

, t h e n t h e e v a p or a t ion r a t e ins ide a b uilding w ill b e m u c h

low e r t h a n a c o r r e s p onding e v a p or a t ion r a t e out s ide ( a s s u m ing t h e t e m p e r a t ur e is t h e s a m e )

. T h e r a t e w ill only b e ( 0

. 1/1. 5) 0. 78

, a b o u t 12 pe r c e n t o f th e r a t e f

o r

a w o r st c a se , a n d ( 0

. 1/3) 0. 78

, a b o u t se v e n pe r c e n t o f th e

rat e fo r an al t e rn at i v e c a s e

.

T h e e v a p or a t e d liq uid m i x e s w i t h a nd c ont a m ina t e s t h e a i r in t h e b uilding. Wha t EP A is ult im a t e l y int e r e s t e d in is t h e r a t e a t w hic h t his c ont a m ina t e d a i r e x it s t h e b uilding. I n or de r t o c a lc ula t e t h e r e le a s e of

c ont a m ina t e d a i r out s ide t h e b uilding, EP A a d a p t e d a m e t hod f r o m a n UK He a l t h a nd Safe t y E x e c u t i v e p a p e r

e n ti tl e d

, R isk M itigation in L and U s e P lanning: I ndoor R e le ase s of T o x i c G ase s , b y S. R. Po rt e r

. E P A

a s s u m e d t h a t t h e t i m e f

o r

c o m p le t e e v a p or a t ion of t h e liq uid p ool w a s one hour

. T h e r a t e a t w hic h

c ont a m ina t e d a i r w a s r e le a s e d f

r o m t h e b uilding dur ing liq uid e v a p or a t ion ( b a s e d on t h e p a p e r ) w a s a s s u m e d

t o b e e q ua l t o t h e e v a p or a t ion r a t e p lus t h e b uilding ve nt ila t ion r a t e ( no p r e s s u r e b uildup in b uilding)

. T h e b uilding ve nt ila t ion r a t e w a s s e t e q ua l t o 0

. 5 a i r c h a nge s p e r hour

. T his ve nt ila t ion r a t e is r e p r e s e n t a t ive of a

s p e c i a lly de s igne d, “ g a s

- t ight ” b uilding. ( T he m i t iga t ion f a c t o r de ve lop e d b a s e d on t his t y p e of b uilding

w ould ove r s t a t e t h e m i t iga t ion p r ovide d b y a b uilding w i t h highe r ve nt ila t ion r a t e s .) EP A us e d a b uilding

3 2 2 w i t h a volum e of 1

, 000 c u bi c m e t e r s ( m ) a n d a f loor a r e a of 200 m ( 2

, 152 f t ) a s a n e x a m pl e f

o r

th i s

a n a l y s is

. EP A a s s u m e d t h a t t h e liq uid p ool w ould c ove r t h e e n t i r e b uilding f loor , r e p r e s e n t ing a c ons e r va t ive

s cen a r i o

.

A

p r i l 15, 1999 D - 5Ap p e ndix D

T e c hnic a l Ba c kgr ound

T o p r ovide a c ons e r va t ive e s t i m a t e , EP A c a lc ula t e d t h e e v a p or a t ion r a t e f

o r

a s p ill of a vola t ile liq uid, c a r b on dis ulf ide ( C S )

, unde r a m b i e n t c ondit ions ins ide t h e b uilding: 2

QR = 0. 1 0. 78 × 0. 075 × 2, 152 = 26. 8 p ounds p e r m inut e ( l bs/m i n )

3 Ne x t

, t his e v a p or a t ion r a t e w a s c onve r t e d t o c u b i c m e t e r s p e r m inut e ( m / m in) us ing t h e ide a l ga s la w ( t he m ole c ula r w e ight of C S is 7 6

. 1 ) : 2

3 3 26. 8 l bs/m i n × 454 g r a m s pe r p ound ( g / l b ) × 1 m ole C S /76. 1 g × 0. 0224 m / m o l e = 3. 58 m / m i n

. 2

3 T h e ve nt ila t ion r a t e of t h e b uilding is 0

. 5 c h a nge s p e r hour , w hic h e q ua ls 500 m pe r hour , or 8

. 3 3

3 m / m in. T h e r e f or e , dur ing e v a p or a t ion, c ont a m ina t e d a i r is le a ving t h e b uilding a t a r a t e of 8

. 3 3 + 3

. 5 8

, or

3 11. 9 m / m i n

.

EP A us e d a n it e r a t ive c a lc ula t ion f o r

c a r b on dis ulf ide le a ving a b uilding us ing t h e a b ove c a lc ula t e d

p a r a m e t e r s

. Dur ing t h e f

i r s t m inut e of e v a p or a t ion, 2 6

. 8 lb s of p u r e c a r b on dis ulf ide e v a p or a t e s , a nd EP A

a s s u m e d t his e v e nly dis p e r s e s t h r ough t h e b uilding s o t h a t t h e c onc e n t r a t ion of C S in t h e b uilding a i r is 2 3 3 0. 0268 l bs/m ( a ssu m ing 1000 m volum e in t h e b uilding)

. C ont a m ina t e d a i r is e x it ing t h e b uilding a t a r a t e

3 o f

11. 9 m / m i n , so E P A d e d u c e d th a t 11. 9 × 0. 0268 = 0. 319 l bs o f c a r b o n d i s u l f i d e e x i t th e b uilding in t h e f i r s t m inut e , le a ving 2 6

. 5 lb s s t ill e v e nly dis p e r s e d ins ide

. S inc e t his r e le a s e oc c u r s ove r one m inut e , t h e

r e l e a s e r a t e o f th e c a r b o n d i s u l f i d e to th e o u tsi d e i s 0. 319 l bs/m i n

. D u r ing t h e s e c ond m inut e , a not he r 2 6

. 8

lb s of p u r e c a r b on dis ulf ide e v a p or a t e s a nd dis p e r s e s , s o t h a t t h e b uilding now c ont a ins 2 6

. 8 + 2 6

. 5 = 5 3

. 3

l bs o f c a r b o n d i s u l f i d e , o r 0. 0533 l bs/m

. 3 C o n t a m i n a te d a i r i s st ill e x it ing t h e b uilding a t a r a t e of 1 1

. 9

3 m / m i n , so 11. 9 × 0. 05328 = 0. 634 l bs o f c a r b o n d i s u l f i d e a r e r e l e a s e d

, l e a ving 5 2

. 6 lb s ins ide

. Aga in, t his

r e le a s e oc c u r s ove r one m inut e s o t h a t t h e r a t e of c a r b on dis ulf ide e x it ing t h e b uilding in t e r m s of

c o n t a m i n a te d a i r i s 0. 634 l bs/m i n

. E P A c o n t inue d t o p e r f o r m t his e s t i m a t ion ove r a p e r iod of one hour

. T h e

r a t e of r e le a s e of c a r b on dis ulf ide e x it ing t h e b uilding in t h e c ont a m ina t e d a i r a t t h e s i x t y m inut e m a r k is 1 3

. 7

l bs/m i n

. Th i s r e pr e s e n ts th e m a xi m u m r a t e o f c a r b o n d i s u l f i d e l e a ving t h e b uilding. Af t e r a ll of t h e c a r b on dis ulf ide is e v a p or a t e d , t h e r e is a dr op in t h e c onc e n t r a t ion of c a r b on dis ulf ide in t h e c ont a m ina t e d a i r le a ving

t h e b uilding b e c a us e t h e e v a p or a t ion of c a r b on dis ulf ide no longe r c ont r i b u t e s t o t h e ove r a ll c ont a m ina t ion of

t h e ai r.

Not e t h a t if t h e s a m e s i z e p ool of c a r b on dis ulf ide f

o r m e d out s ide , t h e r e le a s e r a t e f

o r

a w o r s t

- c a s e

s c e n a r io w ould b e :

QR = 1. 5 0. 78 × 0. 075 × 2, 152 = 221 l bs/m i n

.

an d fo r an al t e rn at i v e c a s e :

QR = 3 0. 78 × 0. 075 × 2, 152 = 380 l bs/m i n

.

T h e m a x i m u m r e le a s e r a t e of c a r b on dis ulf ide in t h e c ont a m ina t e d b uilding a i r , a s s u m ing a 1

, 000 m 3

b uilding w i t h a b uilding e x c h a nge r a t e of 0

. 5 a i r c h a nge s p e r hour , w a s only a b out 6 p e r c e n t ( 1 3

. 7 ÷ 2 2 1

l bs/m i n x 100) o f th e w o r st- c a se sc e n a r i o r a t e , a n d only a b out 3

. 6 p e r c e n t ( 1 3

. 7 ÷ 380 l bs/m i n x 100) o f th e

a l t e r n a t ive s c e n a r io r a t e

. EP A s e t a n ove r a ll b uilding m i t iga t ion f a c t o r e q ua l t o 1 0 p e r c e n t a nd f ive p e r c e n t

,

r e s p e c t ive ly , in or de r t o b e c ons e r va t ive

. P l e a s e not e t h a t ( a t a c ons t a nt ve nt ila t ion r a t e of 0

. 5 c h a nge s p e r

A

p r i l 15, 1999 D - 6Ap p e ndix D

T e c hnic a l Ba c kgr ound

hour ) a s t h e s i z e of t h e b uilding inc r e a s e s , t h e m a x i m u m r a t e of c ont a m ina t e d a i r le a ving t h e b uilding w ill

de c r e a s e , a l t hough only s light ly , b e c a us e of t h e b a la nc ing e f f e c t of b uilding volum e a nd ve nt ila t ion r a t e

. O b vious ly , a highe r ve nt ila t ion r a t e w ill y i e ld a highe r m a x i m u m r e le a s e r a t e of c ont a m ina t e d a i r f

r o m t h e b uilding.

F o r a r e le a s e ins ide a b uilding, EP A a s s u m e d a b uilding a i r ve loc it y of 0

. 1 m / s

. T his c ons e r va t ive

va lue w a s de r ive d b y s e t t ing t h e s i z e of t h e ve nt ila t ion f a n e q ua l t o 1

. 0 m

. 2 T his f a n is e x c h a nging a i r f

r o m

3 t h e b uilding w i t h t h e out s ide a t a r a t e of 0

. 5 c h a nge s p e r hour

. F o r a 1

, 000 m b uilding, t his va lue b e c o m e s

3 3 3 500 m / hour , or 0

. 1 4 m / s

. Dividing 0

. 1 4 m / s b y t h e a r e a of t h e f

a n y i e lds a ve loc it y of 0

. 1 4 m / s , w hic h w a s

r ounde d dow n t o 0

. 1 m / s

.



### D

. 3 T ox ic E ndpoints

T h e t o x i c e ndp oint s f o r

r e gula t e d t o x i c s u bsta n c e s , w h i c h a r e spe c i f i e d i n th e RMP Ru l e , are

p r e s e n t e d in Ap p e ndix B

, Ex hib it s B

- 1 , B

- 2 , a nd B

- 3

. T h e e ndp oint s w e r e c hos e n a s f ollow s , in or de r of

p r ef er en ce:

( 1 ) E m e r ge nc y R e s p ons e P l a nning G uide line 2 ( E R P G

- 2 )

, de ve lop e d b y t h e Am e r ic a n I ndus t r ia l Hy gie ne As s o c i a t ion, if a v a ila b l e ;

( 2 ) L ev el o f C o n cer n ( L O C ) d e r i v e d f

o r

ex t r emel y h azar dous s u bsta n c e s ( E H S s) r e gula t e d

unde r s e c t ion 302 o f th e E m e r g e n c y P l a nning a nd C o m m

unit y R ight

- t o- K now Ac t ( E PCRA ) ( s ee t h e T e c hnic al G uidanc e for H azards A naly sis f o r

m o r e inf or m a t ion on LO C s ) ; t h e LO C f o r

EHS s is b a s e d on:

- - O n e- t e n t h o f t h e Immed i a t e l y D a n g e r o u s t o L i f e a n d H e a l t h ( I DLH) le ve l,

de ve lop e d b y t h e Na t iona l I n s t i t u t e of O c c u p a t iona l Safe t y an d H e al t h (N I O SH ),

us ing I DLH va lue s de ve lop e d b e f o r e 1994,

or , if no I DLH va lue is a v a ila b l e ,

- - O n e

- t e nt h of a n e s t i m a t e d I DLH de r ive d f r o m t o x i c i t y da t a ; t h e I DLH is e s t i m a t e d

a s de s c r i b e d in Ap p e ndix D of t h e T e c hnic al G uidanc e for H azards A naly sis

.

Not e t h a t t h e LO C s w e r e not up da t e d us ing I DLHs p u b lis he d in 1994 a n d l a te r , b e c a us e NI O S H r e vis e d it s m e t hodology f

o r

t h e I DLHs

. T h e EHS LO C s b a s e d on

e a r lie r I DLHs w e r e r e vie w e d b y EP A’ s S c ie nc e Advis or y B o a r d , a nd EP A de c ide d

t o r e t a in t h e m e t hodology t h a t w a s r e vie w e d.

ER P G

- 2 is de f ine d a s t h e m a x i m u m a i r b or ne c onc e n t r a t ion b e low w hic h it is b e lie ve d ne a r l y a l l

individua ls c ould b e e x p o s e d f o r

up t o one hour w i t hout e x p e r i e n c ing or de ve lop ing ir r e ve r s ib le or ot he r

s e r ious he a l t h e f f e c t s or s y m p t o m s t h a t c ould im p a ir a n individua l' s a b ilit y t o t a ke p r ot e c t ive a c t ion.

I DLH ( p r e

- 1994) c o n c e n tr a t ions w e r e de f ine d in t h e NI O S H Po cket G uide to C h e m ic al H azards as

r e p r e s e n t ing t h e m a x i m u m c onc e n t r a t ion f r o m w hic h, in t h e e v e n t of r e s p i r a t or f

a ilur e , one c ould e s c a p e

w i t hin 3 0 m inut e s w i t hout a r e s p i r a t or a nd w i t hout e x p e r i e n c ing a n y e s c a p e

- i m p a i r ing ( e .g., s e ve r e e y e

A

p r i l 15, 1999 D - 7Ap p e ndix D

T e c hnic a l Ba c kgr ound

ir r i t a t ion) or ir r e ve r s ib le he a l t h e f f e c t s

. ( A s not e d a b ove , LO C s f o r

EHS s w e r e not up da t e d t o r e f l e c t 1994

a nd la t e r I DLHs .)

T h e e s t i m a t e d I DLH is de r ive d f r o m a nim a l t o x i c i t y da t a , in or de r of p r e f e r r e d da t a , a s f ollow s :

� F r o m m e dia n le t h a l c onc e n t r a t ion ( L C 50 ) ( inha la t ion) : 0

. 1 x LC 50

� F r o m low e s t le t h a l c onc e n t r a t ion ( L C LO ) ( inha la t ion) : 1 x LC LO

� Fro m m e d i a n l e t h al d o s e (L D 50 ) (o ral ): 0

. 0 1 x L D 50

� Fro m l o w e s t l e t h al d o s e (L D LO ) (o ral ): 0

. 1 x L D LO

T h e t o x i c e ndp oint s b a s e d on LO C s f o r

EHS s p r e s e n t e d in t h e t a b l e s in Ap p e ndix B a r e , in s o m e

c a s e s , dif f e r e nt f r o m t h e LO C s lis t e d in t h e T e c hnic al G uidanc e for H azards A naly sis

, b eca u s e s o me o f t h e LO C s w e r e up da t e d b a s e d on I DLHs t h a t w e r e p u b lis he d a f t e r t h e de ve lop m e n t of t h e LO C s ( a nd b e f o r e 1994) o r o n n e w o r r e v i s e d to xi c i ty d a ta

.



### D

. 4 R e f e r e n c e T a bl e s f o r D i s t anc e s to T o x i c and F l am m a bl e E ndpoints

D. 4. 1 N eut r al l y B u oyant Gas e s

To xi c S u bsta n c e s

. R e f e r e n c e ta bl e s f o r

d i sta n c e s to to xi c e n d p o i n ts f o r

n e u t r a l l y bu o y a n t g a se s a n d

va p o r s w e r e de r ive d f r o m t h e G a us s i a n m ode l us ing t h e longit udina l dis p e r s ion c o e f f i c i e n t s b a s e d on w o r k b y Be al s ( G uide to L o c al D iffusion of A ir Pollutants , T e c hnic a l R e p o r t 214. S c o tt A i r F o r c e B a s e , I llinois : U

. S

. A i r F o r c e , A i r W e a t h e r S e r v i c e , 1971)

. Th e r e a s o n s f o r

u s ing t h e B e a l s dis p e r s ion c o e f f i c i e n t s a r e dis c u s s e d b e low

.

Longit udina l dis p e r s ion ( dis p e r s ion in t h e a long- w ind dir e c t ion) is ge ne r a t e d m o s t l y b y ve r t ic a l w ind

s h e a r

. Wind s h e a r r e s ult s f r o m t h e t e nde nc y of t h e w ind s p e e d t o a s s u m e a w ind p r of ile

— t he s p e e d is low e s t

ne x t t o t h e gr ound a nd inc r e a s e s w i t h he ight unt il it r e a c he s a n a s y m p t o t i c va lue a t a p p r ox im a t e l y a f e w hundr e d f

e e t a b ove t h e s u r f a c e

. T o a c c ount f o r

s h e ar-d ri v e n d i s p e rs ion, a n y a i r dis p e r s ion m ode l int e nde d f o r

m ode ling s hor t

- dur a t ion r e le a s e s m u s t inc lude e i t h e r (a) a fo rm u l a t ion t h a t a c c ount s , e i t h e r im p lic it ly or

e x p lic it ly , f o r

t h e he ight

- d e p e nde nc e of w ind s p e e d or ( b ) s o m e t y p e of p a r a m e t e r iz a t ion t h a t c onve r t s s h e a r

e f

f e c t int o �
x , t h e s t a nda r d de via t ion f unc t ion in t h e a long- w ind dir e c t ion.

B e c a us e t h e s t a nda r d G a us s i a n f o r m ula doe s not inc or p o r a t e �
x ( i t inc lude s only � y a nd �
z , t h e

c r os s w ind a nd hor iz ont a l f unc t ions )

, ve r y f

e w a l t e r n a t e w a y s t o f o r m ula t e �
x ha ve b e e n p r op os e d

. T h e

s i m p le s t m e t hod w a s p r op os e d b y T u r n e r ( W ork book of A t m osphe ric D ispe rsion E stim ate s , Re p o rt PB-1 9 1

482. R e se a r c h Tr i a ngle Park

, N o r t h Car olina : O f f i c e of Air P r ogr a m s , U.S

. Envir onm e n t a l P r o t e c t ion

A g e n c y , 1970)

, w h o s ugge s t e d s i m p ly s e t t ing �
x e q ua l t o � y . T e x t b ooks s u c h a s t h a t b y P a s q uill a nd S m it h ( A t m osphe ric D iffusion

, 3r d e d

. N e w Y o r k : H a l ste a d P r e ss, 1983) d e sc r i be a w e l l

- know n a n a l y t ic m ode l.

How e v e r , t his m ode l is m o r e c o m p le x t h a n a G a us s i a n m ode l b e c a us e a c c o r ding t o it , dis p e r s ion de p e nds on

w ind s h e a r a nd t h e ve r t ic a l va r i a t ion of t h e ve r t ic a l dif f u s ion c o e f f i c i e n t

. Wils on ( Along- w ind Dif f u s ion of

S o u r c e Tr a n si e n ts, A t m osphe ric E n v ironm e n t 15: 489- 495, 1981) pr o p o s e d a n o t h e r m e t hod in w hic h �
x is

A

p r i l 15, 1999 D - 8Ap p e ndix D

T e c hnic a l Ba c kgr ound

de t e r m ine d a s a f unc t ion of w ind s h e a r , b u t in a f o r m t h a t c a n t h e n b e us e d in a G a us s i a n m ode l. How e v e r , it

is now b e lie ve d t h a t Wils on' s f o r m ula t ion give s �
x va lue s t h a t a r e t oo la r g e

.

T o a void t h e p r ob le m s of t h e a n a l y t ic m e t hod a nd Wils on' s f o r m ula t ion, w e c hos e t o inc lude a f o r m ula t ion f o r �
x d e r i v e d f

r o m w o r k by B e a l s ( 1971)

. W e h a d th r e e r e a s o n s f o r doing s o

. F i r s t

, in t e r m s of

m a gnit ude , B e a l s ' �
x f

e ll in t h e m idr a nge of t h e a l t e r n a t ive f

o r m ula t ions t h a t w e r e vie w e d. S e c ond, B e a l s ' �
x indir e c t ly a c c ount s f o r

w ind s h e a r b y us ing ( unp ub lis he d) e x p e r i m e n t a l da t a

. T hir d, b o t h t h e ALO HA a n d

DEG ADI S m ode ls inc or p o r a t e t h e B e a l s m e t hodology

.

W h e n a su bsta n c e i s d i spe r s e d d o w n w ind, t h e c onc e n t r a t ion in t h e a i r c h a nge s ove r t i m e

. T o a s s e s s th e h e a l th e f f e c ts o f po te n t i a l e xpo su r e to th e su bsta n c e , th e a v e r a g e c o n c e n tr a t ion of t h e s u bsta n c e o v e r

s o m e t i m e p e r iod is de t e r m ine d. Ave r a ging t i m e is t h e t i m e int e r va l ove r w hic h t h e ins t a nt a n e ous

c onc e n t r a t ion of t h e h azar dous m a t e r i a l in t h e va p o r c loud is a v e r a g e d

. Ave r a ging t i m e s hould ge ne r a lly b e

e q ua l t o or s hor t e r t h a n e i t h e r t h e r e le a s e dur a t ion or c loud dur a t ion a nd, if p o s s i b l e , s hould r e f l e c t t h e

e x p o s u r e t i m e a s s o c i a t e d w i t h t h e t o x i c e x p o s u r e guide line of int e r e s t

. T h e e x p o s u r e t i m e a s s o c i a t e d w i t h t h e

t o x i c e ndp oint s s p e c i f i e d unde r t h e RMP Ru l e i n c lude 3 0 m inut e s f o r

t h e Immed i a t e l y D a n g e r o u s t o L i f e a n d

He a l t h ( I DLH) le ve l a nd 6 0 m inut e s f o r

t h e Em e r ge nc y R e s p ons e P l a nning G uide line ( E R P G )

. F o r t h e

ne ut r a lly b uoy a n t t a b l e s , t h e 1 0

- m inut e r e le a s e s c e n a r io w a s m ode le d us ing a 1 0

- m inut e a v e r a ging t i m e

. T h e
6 0

- m inut e r e le a s e s c e n a r io w a s m ode le d us ing a 3 0

- m inut e a v e r a ging t i m e t o b e c ons is t e nt w i t h t h e 3 0

-

m

inut e e x p o s u r e t i m e a s s o c i a t e d w i t h t h e I DLH. A 6 0

- m inut e a v e r a ging t i m e m a y ha ve unde r p r e dic t e d

c ons e q ue nc e dis t a nc e s a nd, t h e r e f or e , w a s not us e d f

o r

de ve lop m e n t of t h e dis t a nc e t a b l e s f o r

t his guida nc e

.

C loud dis p e r s ion f r o m a r e le a s e of f

init e dur a t ion ( 1 0 a nd 6 0

- m inut e r e le a s e s ) is c a lc ula t e d us ing a n

e q ua t ion s p e c i f i e d in t h e NO AA p u b lic a t ion A L O H A TM 5. 0 T h e ore tic al D e sc ription , T e c hnic a l M e m o r a ndum

NO S O R C A 6 5

, Augus t 1992.

F l a m m a bl e S u bsta n c e s

. T h e r e f e r e nc e t a b l e s of dis t a nc e s f o r

va p o r c loud f i r e s of ne ut r a lly b uoy a n t
f l a m m a bl e su bsta n c e s w e r e d e r i v e d u s ing t h e s a m e m ode l a s f o r

t o x i c s u bsta n c e s , a s d e sc r i be d a b o v e

. Th e

e ndp oint f o r

m ode ling w a s t h e low e r f

l a m m a b ilit y lim it ( L F L )

. F o r f

l a m m a b l e s u bsta n c e s , a n a v e r a ging t i m e of

0

. 1 m inut e ( s ix s e c onds ) w a s us e d , b e c a us e f

i r e s a r e c ons ide r e d t o b e ne a r l y ins t a nt a n e ous e v e n t s

.

D i sta n c e s o f i n t e r e st f o r

f

l a m m a bl e su bsta n c e s a r e g e n e r a l l y m u c h sh o r te r th a n f o r

to xi c su bsta n c e , b e c a us e t h e LF L c onc e n t r a t ions a r e m u c h la r g e r t h a n t h e t o x i c e ndp oint s

. F o r t h e s hor t dis t a nc e s f ound in

m ode ling t h e f

l a m m a b l e s u bsta n c e s , m o d e ling r e s ult s w e r e f

ound t o b e t h e s a m e f

o r

1 0

- m inut e a nd longe r

r e le a s e s ; t h e r e f or e , one t a b l e of dis t a nc e s f o r

r u r a l c ondit ions a nd one t a b l e f

o r

ur b a n c ondit ions , a p p lic a b le

f o r

b o t h 1 0

- m inut e a nd longe r r e le a s e s , w e r e de ve lop e d f

o r

f

l a m m a b l e s u bsta n c e s

.



### D

. 4

. 2 D en se G a ses

To xi c S u bsta n c e s

. T h e r e f e r e nc e t a b l e s f o r

de ns e ga s e s w e r e de ve lop e d us ing t h e w ide ly a ccep t e d

S LAB m ode l, de ve lop e d b y La w r e n c e Live r m or e Na t iona l La b o r a t or y

. S LAB s olve s c ons e r va t ion e q ua t ions

of

m a s s , m o m e n t u m , e n e r gy , a nd s p e c i e s f o r

c ont inuous , f init e dur a t ion, a nd ins t a nt a n e ous r e le a s e s

. T h e

r e f e r e nc e t a b l e s w e r e b a s e d on t h e e v a p or a t ing p ool a lgor it hm

.

F o r t h e r e f e r e nc e t a b l e s w e r e de ve lop e d b a s e d on m ode ling r e le a s e s of hy dr oge n c hlor ide ( H C l )

. HC l

w a s c hos e n b a s e d on a S LAB m ode ling a n a l y s is of a r a nge of dis p e r s ion b e ha vior f

o r

r e le a s e s of r e gula t e d

A

p r i l 15, 1999 D - 9Ap p e ndix D

T e c hnic a l Ba c kgr ound

de ns e ga s e s or va p o r s w i t h dif f e r e nt m ole c ula r w e ight s

. T his a n a l y s is s how e d t h a t r e le a s e s of HC l ge ne r a lly

p r ovide d c ons e r va t ive r e s ult s unde r a va r i e t y of s t a b ilit y / w ind s p e e d c o m b ina t ions , r e le a s e r a t e s , a nd t o x i c

e ndp oint s

.

S i m ila r t o t h e m ode ling of ne ut r a lly b uoy a n t p lum e s , t h e 1 0

- m inut e r e le a s e s c e n a r io of t o x i c

c h e m i c a ls w a s m ode le d us ing a 1 0

- m inut e a v e r a ging t i m e

. T h e 6 0

- m inut e r e le a s e s c e n a r io w a s m ode le d

us ing a 3 0

- m inut e a v e r a ging t i m e t o b e c ons is t e nt w i t h t h e 3 0

- m inut e e x p o s u r e t i m e a s s o c i a t e d w i t h t h e
I DLH.

F o r a ll de ns e ga s t a b l e s , t h e r e f e r e nc e he ight f o r

t h e w ind s p e e d w a s 1 0 m e t e r s

. R e la t ive hum idit y

o w a s a ssu m e d to be 50 pe r c e n t, a n d th e a m bi e n t te m p e r a t u r e w a s 25 C

. Th e so u r c e a r e a w a s th e sm a l l e st

va lue t h a t s t ill e n a b le d t h e m ode l t o r un f o r

a ll r e le a s e r a t e s

. T h e s u r f a c e r oughne s s f a c t o r w a s one m e t e r f

o r

u r b a n s cen a r i o s a n d t h r ee cen t i met er s f o r

r u r a l s cen a r i o s

.

F l a m m a bl e S u bsta n c e s

. F o r t h e r e f e r e nc e t a b l e s f o r

dis p e r s ion of de ns e f

l a m m a b l e ga s e s a nd va p o r s , f o r

a n a l y s is of va p o r c loud f i r e s , t h e s a m e m ode l w a s us e d a s f o r

t o x i c s u bsta n c e s , a s d e sc r i be d a b o v e , a n d

t h e s a m e a s s u m p t ions w e r e m a de

. F o r t h e dis p e r s ion of f

l a m m a b l e c h e m i c a ls , a v e r a ging t i m e s hould b e ve r y

s m a ll ( i .e ., no m o r e t h a n a f e w s e c onds )

, b e c a us e f

l a m m a b l e va p o r s ne e d only b e e x p o s e d t o a n ignit ion

s our c e f

o r

a s hor t p e r iod of t i m e t o init ia t e t h e c o m b us t ion p r oc e s s

. T hus , b o t h t h e 1 0

- m inut e a nd 6 0

- m inut e

r e f e r e n c e ta bl e s f o r

f

l a m m a bl e su bsta n c e s u s e a n a v e r a ging t i m e of 1 0 s e c onds

. T h e 1 0

- m inut e a nd 6 0

-

m

inut e t a b l e s w e r e c o m b ine d f o r

f

l a m m a b l e s u bsta n c e s be c a u s e th e m o d e ling r e s ult s w e r e f

ound t o b e t h e

s a me.



### D. 4. 3 C h e m i cal

- S p eci f i c Ref e r e n ce Tab l es

T h e c h e m i c a l- s p e c i f i c r e f e r e nc e t a b l e s of dis t a nc e s f o r

a m m onia , c hlor ine , a nd s ulf ur

diox ide w e r e d e v e l o p ed f

o r

E P A ’ s r i s k ma n a g emen t p r o g r a m guida nc e f

o r

a m m onia r e f r ige r a t ion a nd f o r

P O T W s

. F o r inf or m a t ion on t h e c h e m i c a l- s p e c i f i c m ode ling a nd de ve lop m e n t of t h e c h e m i c a l- s p e c i f i c r e f e r e nc e t a b l e s , s e e
B a c k up I nform ation for the H azard A sse ssm e nts in the R M

P

O

ffsite C onse que nc e A naly sis G uidanc e , the

G uidanc e for W aste w ate r T r e atm e nt F a c ilitie s and the G uidanc e for A m m onia R e frige ration - A nhy drous

A m m onia, A que ous A m m onia, C hlorine and Sulfur D iox ide

. S e e a l s o t h e indus t r y

- s p e c i f i c guida nc e doc um e n t s f o r

a m m onia r e f r ige r a t ion a nd P O T W s

.

T h e m ode ling c arri e d o u t fo r aq u e o u s am m onia a l s o is a p p lie d in t his guida nc e t o a m m onia r e le a s e d

a s a ne ut r a lly b uoy a n t p lum e in ot he r s i t u a t ions

. T h e t a b l e s of dis t a nc e s de r ive d f r o m t his m ode ling w ould

a p p l y t o e v a p or a t ion of a m m onia f r o m a w a t e r s olut ion, e v a p or a t ion of a m m onia liq ue f i e d b y r e f r ige r a t ion, or

a m m onia r e le a s e s f r o m t h e va p o r s p a c e of a ve s s e l, b e c a us e t h e a m m onia w ould b e ha ve a s a ne ut r a lly

bu o y a n t pl u m e ( o r po ssi bl y bu o y a n t i n so m e c a se s)

.



### D. 4. 4 C h o i ce of Ref e r e n ce Tab l e f o r Di sp er si on Di st an ces

Ga se s

. Ex hib it B

- 1 of Ap p e ndix B indic a t e s w h e t he r t h e r e f e r e nc e t a b l e s f o r

ne ut r a lly b uoy a n t or de ns e ga s e s s hould b e us e d f

o r

e a c h of t h e r e gula t e d t o x i c ga s e s

. Ex hib it C

- 2 , Ap p e ndix C

, p r ovide s t his

inf or m a t ion f o r

f

l a m m a b l e ga s e s

. T h e c hoic e of r e f e r e nc e t a b l e p r e s e n t e d in t h e s e e x hib it s is b a s e d on t h e

m ole c ula r w e ight of t h e r e gula t e d s u bsta n c e c o m p a r e d to a i r ; h o w e v e r , a n u m be r o f f

a c to r s th a t m a y c a u s e a

su bsta n c e w i th a m o l e c u l a r w e ight s i m ila r t o or s m a lle r t h a n t h e m ole c ula r w e ight of a i r t o b e ha ve a s a de ns e

A

p r i l 15, 1999 D - 10Ap p e ndix D

T e c hnic a l Ba c kgr ound

ga s s hould b e c ons ide r e d in s e le c t ing t h e a p p r op r i a t e t a b l e

. F o r e x a m p l e , a c old ga s m a y b e ha ve a s a de ns e

ga s , e v e n if it is light e r t h a n a i r a t a m b i e n t t e m p e r a t ur e

. G a s e s liq ue f i e d unde r p r e s s u r e m a y b e r e le a s e d a s a

m

i x t u r e of va p o r a nd liq uid dr op le ts; be c a u s e o f pr e s e n c e o f l i q uid m i x e d w i t h t h e va p o r , a ga s t h a t is light e r

t h a n a i r m a y b e ha ve a s a de ns e ga s in s u c h a r e le a s e

. A ga s t h a t p oly m e r iz e s or f

o r m s hy dr oge n b onds ( e .g., hy dr oge n f luor ide ) a l s o m a y b e ha ve a s a de ns e ga s

.

Liq uids a nd S olut ions

. Ex hib it s B

- 2 a nd B

- 3 , Ap p e ndix B

, a nd Ex hib it C

- 3 , Ap p e ndix C

, indic a t e

t h e r e f e r e nc e t a b l e of dis t a nc e s t o b e us e d f

o r

e a c h r e gula t e d liq uid. T h e m e t hodology p r e s e n t e d in t his guida nc e f

o r

c ons e q ue nc e a n a l y s is f o r

liq uids a nd s olut ions a s s u m e s e v a p or a t ion f r o m a p ool. All of t h e liq uids r e gula t e d unde r C AA s e c t ion 1 1 2 (r) h a v e m o l e c u l ar w e ight s gr e a t e r t h a n t h e m ole c ula r w e ight of a i r ;

t h e r e f or e , t h e i r va p o r w ould b e he a vie r t h a n a i r

. How e v e r , b e c a us e t h e va p o r f

r o m a p ool w ill m i x w i t h a i r a s it e v a p or a t e s , t h e init ia l de ns it y of t h e va p o r w i t h r e s p e c t t o a i r m a y not in a ll c a s e s indic a t e w h e t he r t h e va p o r

r e le a s e d f

r o m a p ool s hould b e m ode le d a s a de ns e ga s or a ne ut r a lly b uoy a n t ga s

. I f t h e r a t e of r e le a s e f

r o m

t h e p ool is r e la t ive ly low , t h e va p o r-ai r m i x t u re t h at i s g e n e rat e d m a y b e n e u t ral l y b u o y an t e v e n i f t h e v a p o r i s d e n s e r t h an ai r, b e c a u s e t h e m i x t u re m a y c o n t ai n a re l a t i v e l y s m al l frac t ion of t h e de ns e r

- t ha n- a i r va p o r ; i.e

. , it m a y b e m o s t l y a i r

. T his m a y b e t h e c a s e p a r t ic ula r l y f

o r

s o m e of t h e r e gula t e d t o x i c liq uids w i t h r e la t ive ly

low vola t ilit y

. All of t h e r e gula t e d f l a m m a b l e s u bsta n c e s h a v e r e l a ti v e l y high vola t ilit y ; t h e r e f e r e nc e t a b l e s f o r

de ns e ga s e s a r e a s s u m e d t o b e a p p r op r i a t e f

o r

a n a l y z ing dis p e r s ion of t h e s e f

l a m m a b l e liq uids

.

T o ide nt if y

t o x i c liq uids w i t h m ole c ula r w e ight gr e a t e r t h a n a i r t h a t m ight b e ha ve a s ne ut r a lly

b uoy a n t ga s e s w h e n e v a p or a t ing f r o m a p ool, EP A us e d t h e ALO HA m ode l f o r

p ool e v a p or a t ion of a num b e r

o f

su bsta n c e s w i th a r a n g e o f m o l e c u l a r w e ight s a nd va p o r p r e s s u r e s

. M ode ling w a s c arri e d o u t fo r F

s t a b ilit y a nd w ind s p e e d 1

. 5 m e t e r s p e r s e c ond ( w or s t

- c a s e c ondit ions ) a nd f o r

D s t a b ilit y a nd w ind s p e e d 3

. 0

m e t e r s p e r s e c ond ( a l t e r n a t ive

- c a s e c ondit ions )

. P ool s p r e a d t o a de p t h of one c e n t i m e t e r w a s a s s u m e d

. Addit iona l m ode ling w a s c arri e d o u t fo r c o m p ari s o n as s u m ing dif f e r e nt p ool a r e a s a nd de p t h s

. T h e

m ole c ula r w e ight

- v a p or p r e s s u r e c o m b ina t ions a t w hic h ALO HA us e d t h e ne ut r a lly b uoy a n t ga s m ode l w e r e

us e d t o de ve lop t h e r e f e r e nc e t a b l e c hoic e s give n in Ex hib it B

- 2 ( f o r

liq uids ) a nd B

- 3 ( f o r

s olut ions ) in Ap p e ndix B

. T h e ne ut r a lly b uoy a n t t a b l e s s hould ge ne r a lly give r e a s ona b l e r e s ult s f o r

p ool e v a p or a t ion

unde r a m b i e n t c ondit ions w h e n indic a t e d f

o r

liq uids

. At e l e v a t e d t e m p e r a t ur e s , how e v e r , e v a p or a t ion r a t e s

w ill b e gr e a t e r , a nd t h e de ns e ga s t a b l e s s hould b e us e d

.

T h e liq uids f o r

w hic h t h e ne ut r a lly b uoy a n t t a b l e is ide nt if ie d f o r

t h e w o r s t c a s e p r ob a b ly c a n b e

e x p e c t e d t o b e ha ve a s ne ut r a lly b uoy a n t va p o r s w h e n e v a p or a t ing f r o m p ools unde r a m b i e n t c ondit ions in

m o s t s i t u a t ions , b u t t h e r e m a y b e c a s e s w h e n t h e y e x hib it de ns e ga s b e ha vior

. O t h e r liq uids , f o r

w hic h t h e

ne ut r a lly b uoy a n t t a b l e s a r e not indic a t e d f

o r

t h e w o r s t c a s e , m ight r e le a s e ne ut r a lly b uoy a n t va p o r s unde r

o s o m e c ondit ions ( e .g., r e la t ive ly s m a ll p ools , t e m p e r a t ur e not m u c h a b ove 2 5 C )

. S i m ila r l y , t h e liq uids f o r

w hic h t h e ne ut r a lly b uoy a n t t a b l e s a r e indic a t e d a s a p p r op r i a t e f

o r

a l t e r n a t ive s c e n a r io a n a l y s is p r ob a b ly c a n b e c ons ide r e d t o b e ha ve a s ne ut r a lly b uoy a n t va p o r s unde r t h e a l t e r n a t ive s c e n a r io c ondit ions in m o s t c a s e s ; how e v e r , t h e r e m a y b e c a s e s w h e r e t h e y w ill b e ha ve a s de ns e ga s e s , a nd t h e r e m a y b e ot he r liq uids t h a t in

s o m e c a s e s w ould e x hib it ne ut r a lly b uoy a n t b e ha vior w h e n e v a p or a t ing. T h e r e f e r e nc e t a b l e c hoic e s s how n in Ex hib it B

- 2 a r e int e nde d t o r e f l e c t t h e m o s t like ly b e ha vior of t h e s u bsta n c e s; th e y w ill not p r e dic t
b e ha vior of t h e lis t e d s u bsta n c e s e v a p o r a t ing unde r a ll c ondit ions

.

A

p r i l 15, 1999 D - 11Ap p e ndix D

T e c hnic a l Ba c kgr ound



### D. 4. 5 A ddit i onal M o del i ng f o r Com p ar is on

M ode ling w a s c arri e d o u t fo r t w o w o rs t

- c a s e e x am p l e s an d t w o al t e rn at i v e -c as e e x am p l e s , u s ing t w o dif f e r e nt m ode ls , f o r

c o m p a r i s on w i t h t h e r e s ult s ob t a ine d f r o m t h e m e t hods a nd dis t a nc e t a b l e s in t his guida nc e

. T his m ode ling is dis c u s s e d b e low

.

ALO HA M ode l

. T h e Ar e a l Loc a t ions of H azar dous At m o s p h e r e s ( ALO HA) s y s t e m w a s de ve lop e d joint ly b y NO AA a nd EP A. ALO HA Ve r s ion 5

. 2

. 1 w a s us e d f

o r

t h e c o m p a r i s on m ode ling. T h e p a r a met er s f o r

ALO HA m ode ling w e r e t h e s a m e a s s p e c i f i e d in t his guida nc e doc um e n t f o r

w o r s t

- c a s e a nd a l t e r n a t ive

sc e n a r i o s

. Th e su bsta n c e s m o d e l e d a r e i n c lude d in ALO HA’ s c h e m i c a l da t a b a s e , s o no c h e m i c a l da t a w e r e

e n t e r e d f o r

m ode ling. F o r c ons is t e nc y w i t h t h e m e t hodology us e d t o de ve lop t h e r e f e r e nc e t a b l e s of dis t a nc e s ,

a w ind s p e e d he ight of 1 0 m e t e r s w a s s e le c t e d f

o r

ALO HA m ode ling.

F o r a l l o f th e su bsta n c e s m o d e l e d

, th e d i r e c t so u r c e m o d e l w a s c h o s e n f o r

A L O H A m o d e ling, a nd t h e

r e le a s e r a t e e s t i m a t e d us ing t h e guida nc e m e t hodology w a s e n t e r e d a s t h e r e le a s e r a t e f

o r

ALO HA. ALO HA

se l e c t e d th e d e n s e g a s m o d e l to e sti m a te th e d i sta n c e s to th e e n d p o i n ts i n a l l c a se s.

WHAZAN M ode l

. T h e W o r l d Ban k H azard A n a l y s i s ( WHAZAN) s y s t e m w a s de ve lop e d b y T e c hnic a I n t e r n a t iona l in c olla b o r a t ion w i t h t h e Wor ld B a nk. T h e 1988 v e r s ion of WHAZAN w a s us e d f

o r

t h e c o m p a r i s on m ode ling. T h e p a r a m e t e r s f o r

a t m o s p h e r ic s t a b ilit y , w ind s p e e d , a nd a m b i e n t t e m p e r a t ur e

a nd hum idit y w e r e t h e s a m e a s s p e c i f i e d in t his guida nc e doc um e n t

. F o r s u r f a c e r oughne s s , WHAZAN

r e q uir e s e n t r y of a “ r oughne s s p a r a m e t e r ,” r a t he r t h a n a he ight

. B a s e d on t h e dis c u s s ion of t his p a r a met er i n

t h e WHAZAN T h e o r y M a nua l, a r oughne s s p a r a m e t e r of 0

. 0 7 ( c or r e s p onding t o f l a t la nd, f e w t r e e s ) w a s

c hos e n a s e q uiva le nt t o t h e s u r f a c e r oughne s s of 3 c e n t i m e t e r s us e d t o r e p r e s e n t r u r a l t o p ogr a p hy in m ode ling

t o de ve lop t h e dis t a nc e t a b l e s f o r

t his guida nc e

. A r oughne s s p a r a m e t e r of 0

. 1 7 ( f o r

w oods or r u r a l a r e a or indus t r ia l s i t e ) w a s c hos e n a s e q uiva le nt t o 1 m e t e r , w hic h w a s us e d t o de ve lop t h e ur b a n dis t a nc e t a b l e s

. Da t a w e r e a dde d t o t h e WHAZAN c h e m i c a l da t a b a s e f

o r

a c r y lonit r ile a nd a lly l a l c ohol; e t hy le ne ox ide a n d

c hlor ine w e r e a l r e a d y inc lude d in t h e da t a b a s e

.

F o r WHAZAN m ode ling of t h e ga s e s e t hy le ne ox ide a nd c hlor ine a nd t h e liq uid a c r y lonit r ile , t h e WHAZAN de ns e c loud dis p e r s ion m ode l w a s us e d

. F o r t h e a l t e r n a t ive

- c a s e r e le a s e of a lly l a l c ohol, t h e b uoy a n t p lum e dis p e r s ion m ode l w a s us e d f

o r

c ons is t e nc y w i t h t h e guida nc e m e t hodology

. T h e r e le a s e r a t e s

e s t i m a t e d us ing t h e guida nc e m e t hodology w e r e e n t e r e d a s t h e r e le a s e r a t e s f o r

a ll of t h e WHAZAN

m ode ling.

T h e WHAZAN de ns e c loud dis p e r s ion r e q uir e s a “ volum e dilut ion f a c t o r ” a s one of it s inp ut s

. T his

f a c t o r w a s not e x p l a ine d; it w a s p r e s um e d t o a c c ount f o r

dilut ion of p r e s s u r i z e d ga s e s w i t h a i r up on r e le a s e

. F o r t h e ga s e s m ode le d, t h e de f a ult dilut ion f a c t o r of 6 0 w a s us e d ; f o r

a c r y lonit r ile , a dilut ion f a c t o r of 0 w a s

e n te r e d

. Th i s f a c to r a ppe a r s to h a v e l i ttl e e f f e c t o n th e d i sta n c e r e su l ts.



### D

. 5 Wor s t-C as e C o ns e que nc e A n al ys is f o r F l am m a bl e Subs tanc e s

T h e e q ua t ion us e d f

o r

t h e va p o r c loud e x p los ion a n a l y s is f o r

t h e w o r s t c a s e involving f l a m m a b l e

su bsta n c e s i s give n in Ap p e ndix C

. T his e q ua t ion is b a s e d on t h e T N T

- e q uiva le nc y m e t hod of t h e UK He a l t h

an d Safe t y E x e c u t i v e , as p r e s e n t e d i n t h e p u b l i c at ion of t h e C e nt e r f

o r

C h e m i c a l P r o c e s s Safe t y o f t h e Am e r ic a n I n s t i t u t e of C h e m i c a l Engine e r s ( A I C hE)

, G uide line s for E v aluating the C harac te ristic s of V apor

A

p r i l 15, 1999 D - 12Ap p e ndix D

T e c hnic a l Ba c kgr ound

C loud E x

plosions, F lash F ire s, and B L EVEs ( 1994)

. Th e a ssu m pt ion w a s m a de f

o r

t h e w o r s t c a s e t h a t t h e

to ta l qu a n ti ty o f th e r e l e a s e d su bsta n c e i s i n th e f

l a m m a bl e pa r t o f th e c loud. T h e AI C hE doc um e n t li sts th i s

a s s u m p t ion a s one of a num b e r t h a t ha ve b e e n us e d f

o r

va p o r c loud e x p los ion b l a s t p r e dic t ion; it w a s c hos e n

a s a c ons e r va t ive a s s u m p t ion f o r

t h e w o r s t

- c a s e a n a l y s is

. T h e y i e ld f a c t o r of 1 0 p e r c e n t w a s a c ons e r va t ive

w o r s t

- c a s e a s s u m p t ion, b a s e d on inf or m a t ion p r e s e n t e d in t h e AI C hE doc um e n t

. Ac c o r ding t o t h e AI C h E

doc um e n t

, r e p o r t e d va lue s f o r

T N T e q uiva le nc y f

o r

va p o r c loud e x p los ions r a nge f

r o m a frac t ion of one

p e r c e n t t o t e ns of p e r c e n t ; f o r

m o s t m a jor va p o r c loud e x p los ions , t h e r a nge is one t o t e n p e r c e n t

.

T h e e ndp oint f o r

t h e va p o r c loud e x p los ion a n a l y s is , 1 p s i , is r e p o r t e d t o c a us e da m a ge s u c h a s

s h a t t e r ing of gla s s w indow s a nd p a r t ia l de m olit ion of hous e s

. S kin la c e r a t ion f r o m f

l y ing gla s s a l s o is

r e p o r t e d

. T his e ndp oint w a s c hos e n f o r

t h e c ons e q ue nc e a n a l y s is b e c a us e of t h e p o t e nt ia l f o r

s e r ious injur ie s

t o p e op le f

r o m t h e p r op e r t y da m a ge t h a t m ight r e s ult f r o m a n e x p los ion.

T h e T N T e q uiva le nt m ode l w a s c hos e n a s t h e b a s i s f o r

t h e c ons e q ue nc e a n a l y s is b e c a us e of it s

s i m p lic it y a nd w ide us e

. T his m ode l doe s not t a ke int o a c c ount s i t e

- s p e c i f i c f a c t o r s a nd m a ny c h e m i c a ls p e c i f i c f a c t o r s t h a t m a y a f f e c t t h e r e s ult s of a va p o r c loud e x p los ion. O t h e r m e t hods a r e a v a ila b l e f

o r

va p o r

c loud e x p los ion m ode ling; s e e t h e lis t of r e f e r e nc e s in Ap p e ndix A f o r

s o m e p u b lic a t ions t h a t inc lude

inf or m a t ion on ot he r va p o r c loud e x p los ion m ode ling m e t hods

.



### D. 6 A l t er nat i ve Scenar io Anal ys is f o r Gas e s

T h e e q ua t ion f o r

e s t i m a t ing r e le a s e r a t e of a ga s f r o m a hole in a t a nk is b a s e d on t h e e q ua t ions f o r

g a s d i s ch a r g e r a t e p r es en t e d i n t h e H andbook of C h e m ic al H azard A naly sis P roc e dure s b y t h e Fe d e ral

E mer g e n c y M a n a g emen t A g e n c y ( F E M A )

, D O T

, a n d E P A

, a n d eq u a t ions in EP A' s W ork book of Sc re e ning

T

e c hnique s for A sse ssing I m

pac ts of T o x i c A ir P ollutants

. T h e e q ua t ion f o r

a n ins t a nt a n e ous dis c h a r g e unde r non- c hoke d f low c ondit ions is :



### m � C d 

### A h 

### 2 p 0 

### � 0 

### �

�

� 1 p 1



### p 0 2

�



### � p 1



### p 0 � � 1

� 

### (D -7 )

w h er e: m = D i s c h arg e rat e (k g / s )

C

d = D i s ch a r g e co ef f i ci en t

2 A h = O p e ning a r e a ( m )

� = Rat i o o f s p e c i fi c h e at s

p 0 = T an k p r e s s u re (Pas c a l s )

p 1 = A m b i e n t p r e s s u re (Pas c a l s )

3 � 0 = D e n si ty ( k g / m )

Unde r c hoke d f low c ondit ions ( m a x im um f

low r a t e ) , t h e e q ua t ion b e c o m e s :

A

p r i l 15, 1999 D - 13Ap p e ndix D

T e c hnic a l Ba c kgr ound

� � 1 

### 2 �

� 1 

### (D -8 ) m � C d 

### A h 

### � p 0 

### � 0 

### � � 1

F o r de ve lop m e n t of t h e e q ua t ion a nd ga s f a c t o r s p r e s e n t e d in t his guida nc e , de ns it y ( � ) w a s r e w r i tte n

a s a f unc t ion of p r e s s u r e a nd m ole c ula r w e ight , b a s e d on t h e ide a l ga s la w :



### p 0 

### MW � � (D -9 ) R T
t

w h er e: MW = M ole c ula r w e ight ( kilogr a m s p e r kilom ole )

R = G a s c o n sta n t ( 8

, 314 J oule s p e r de gr e e

- kilom ole )

T

t = T an k t e m p e rat u r e (K )

T h e c hoke d f low e q ua t ion c a n b e r e w r it t e n:

� � 1 

### 1 2 MW �

� 1 

### (D -1 0 ) � m � C d 

### A h 

### p 0 

### � � 1 8314 T

t

T o de r ive t h e e q ua t ion p r e s e n t e d in t h e guida nc e , a ll t h e c h e m i c a l- s p e c i f i c p r op e r t i e s , c ons t a nt s , a n d

a p p r op r i a t e c onve r s ion f a c t o r s w e r e c o m b ine d int o t h e "G a s F a c t o r " ( G F )

. T h e dis c h a r g e c o e f f i c i e n t w a s

a s s u m e d t o ha ve a va lue of 0

. 8

, b a s e d on t h e s c r e e ning va lue r e c o m m e nde d in EP A' s W ork book of Sc re e ning

T

e c hnique s for A sse ssing I m

pac ts of T o x i c A ir P ollutants

. T h e G F w a s de r ive d a s f ollow s :

� � 1 

### 2 �

� 1 

### MW (D -1 1 ) � GF � 132. 2 × 6, 895 × 6

. 4516×10

� 4 

### × 0

. 8 � � 1 8314

w h e r e : 132. 2 = C onve r s ion f a c t o r f

o r

l bs/m i n to k g / s
6

, 8 9 5 = C onve r s ion f a c t o r f

o r

p s i t o P a s c a ls ( p ) 0 6. 4516 x 10 -4 = C onve r s ion f a c t o r f

o r

s q u a r e inc he s t o s q u a r e m e t e r s ( A ) h

G F va lue s w e r e c a lc ula t e d f o r

a ll ga s e s r e gula t e d unde r C AA s e c t ion 1 1 2 (r) an d are l i s t e d i n Ap p e ndix B

, Ex hib it B

- 1 , f o r

t o x i c ga s e s a nd Ap p e ndix C

, Ex hib it C

- 2 , f o r

f

l a m m a b l e ga s e s

.

A

p r i l 15, 1999 D - 14Ap p e ndix D

T e c hnic a l Ba c kgr ound

F r o m t h e e q ua t ion f o r

c hoke d f low a b ove a nd t h e e q ua t ion f o r

t h e G F a b ove , t h e init ia l r e le a s e r a t e f o r

a ga s f r o m a hole in a t a nk c a n b e w r it t e n a s :



### QR � HA × P
t 

### × 1

T

t 

### × GF (D -1 2 )

w h er e: QR = R e l e a s e r a t e ( p ounds p e r m inut e )

HA = Hole a r e a ( s q u a r e inc he s )

P

t = T a n k pr e ssu r e ( psi a )

T

t = T an k t e m p e rat u r e (K )



### D. 7 A l t er nat i ve Scenar io Anal ys is f o r L i quids

D

. 7

. 1 R el ea ses fr o m H o l e s i n Ta n k s

T h e e q ua t ion f o r

e s t i m a t ing r e le a s e r a t e of a liq uid f r o m a hole in a t a nk is b a s e d on t h e e q ua t ions f o r liq uid r e le a s e r a t e p r e s e n t e d in t h e H andbook of C h e m ic al H azard A naly sis P roc e dure s by F E M A

, D OT,

a nd EP A a nd EP A' s W ork book of Sc re e ning T e c hnique s for A sse ssing I m

pac ts of T o x i c A ir P ollutants

. T h e e q ua t ion f o r

t h e ins t a nt a n e ous r e le a s e r a t e is :



### � � m � A h 

### C d 

### � l 

### 2 g � l 

### H L 

### H h 

### � 2 P 0 

### P

a 

### (D -1 3 )

w h er e: m = Dis c h a r g e r a t e ( kilogr a m s p e r s e c ond)

A h = O p e ning a r e a ( s q u a r e m e t e r s )

C

d = Dis c h a r g e c o e f f i c i e n t ( unit le s s )

g = G r a vit a t iona l c ons t a nt ( 9 .8 m e t e r s p e r s e c ond s q u a r e d)

� l = Liq uid de ns it y ( kilogr a m s p e r c u b i c m e t e r )

P

0 = S t o rag e p r e s s u re (Pas c a l s )

P

a = A m b i e n t p r e s s u re (Pas c a l s )

H

L = Liq uid he ight a b ove b o t t o m of c ont a ine r ( m e t e r s )

H

h = H e ight of op e ning ( m e t e r s )

A ve r s ion of t his e q ua t ion is p r e s e n t e d in t h e guida nc e f

o r

us e w i t h da t a f ound in Ap p e ndix B

, f o r

ga s e s liq ue f i e d unde r p r e s s u r e

. T h e e q ua t ion in t h e t e x t w a s de r ive d us ing t h e c onve r s ion f a c t o r s lis t e d b e low

a nd de ns it y f

a c t o r s a nd e q uilib r ium va p o r p r e s s u r e or t a nk p r e s s u r e va lue s lis t e d in Ap p e ndix B

, Ex hib it B

- 1

. Eq ua t ion D- 1 3 b e c o m e s :



### QR � 132. 2× 6. 4516× 10
� 4 

### ×0

. 8 × HA 16. 018× d × [ 2× 9. 8× 16. 018× d × LH × 0

. 0254 � 2 P
g 

### × 6895] 

### (D -1 4 )

A

p r i l 15, 1999 D - 15Ap p e ndix D

T e c hnic a l Ba c kgr ound

w h er e: QR = R e l e a s e r a t e ( p ounds p e r m inut e )

HA = Hole a r e a ( s q u a r e inc he s )

132. 2 = C onve r s ion f a c t o r f

o r

kilogr a m s p e r s e c ond t o p ounds p e r m inut e
6. 4516 x 10 -4 = C onve r s ion f a c t o r f

o r

s q u a r e inc he s t o s q u a r e m e t e r s ( HA )

0

. 8 = D i s ch a r g e co ef f i ci en t ( 0

. 8 )

d = Liq uid de ns it y ( p ounds p e r c u b i c f oot ) ; c a n de r ive d b y us ing t h e d e n s i t y f

a c to r : 1/( D F x0. 033)

1 6

. 0 1 8 = C onve r s ion f a c t o r f

o r

p ounds p e r c u b i c f e e t t o kilogr a m s p e r c u b i c

met er s ( D )

9

. 8 = G r a vit a t iona l c ons t a nt ( m e t e r s p e r s e c ond s q u a r e d)

LH = H e ight of liq uid a b ove hole ( inc he s )

2

. 5 4 x 1 0 -2 = C onve r s ion f a c t o r f

o r

inc he s t o m e t e r s ( LH)

P

g = G a u g e pr e ssu r e i n ta n k ( psi )

6

, 8 9 5 = C onve r s ion f a c t o r f

o r

p s i t o P a s c a ls ( P
g )

Af t e r c o m b ining t h e c onve r s ion f a c t o r s a nd inc or p o r a t ing t h e de ns it y f

a c t o r ( D F )

, t his e q ua t ion b e c o m e s :



### 0. 7 669 QR � HA × 6

. 8 2 × LH � × P
g 

### (D -1 5 ) DF 2 

### DF

F o r liq uids s t o r e d a t a m b i e n t p r e s s u r e , Eq ua t ion D- 1 3 b e c o m e s :



### � m � A h 

### C d 

### � l 

### 2 g H L 

### H h 

### (D -1 6 )

T o de r ive t h e e q ua t ion p r e s e n t e d in t h e guida nc e f

o r

liq uids unde r a m b i e n t p r e s s u r e , a ll t h e c h e m i c a ls p e c i f i c p r op e r t i e s , c ons t a nt s , a nd c onve r s ion f a c t o r s w e r e c o m b ine d int o t h e "Liq uid Le a k F a c t o r " ( LLF )

. T h e dis c h a r g e c o e f f i c i e n t w a s a s s u m e d t o ha ve a va lue of 0

. 8

, b a s e d on t h e s c r e e ning va lue r e c o m m e nde d in

EP A' s W ork book of Sc re e ning T e c hnique s for A sse ssing I m

pac ts of T o x i c A ir P ollutants

. T h e LLF w a s de r ive d a s f ollow s :



### LLF � 132. 2 × 6. 4516 × 1 0

� 4 

### × 0

. 1594 × 0

. 8 × 2×9

. 8× � l 

### (D -1 7 )

w h er e: LLF = Liq uid Le a k F a c t o r ( p ounds p e r m inut e

- inc he s 2. 5 )

132. 2 = C onve r s ion f a c t o r f

o r

kilogr a m s p e r s e c ond t o p ounds p e r m inut e ( m )

6. 4516 x 10 -4 = C onve r s ion f a c t o r f

o r

s q u a r e inc he s t o s q u a r e m e t e r s ( A h )

0. 1594 = C onve r s ion f a c t o r f

o r

s q u a r e r oot of inc he s t o s q u a r e r oot of m e t e r s ( H L - H h )

0

. 8 = D i s ch a r g e co ef f i ci en t ( 0

. 8 )

9

. 8 = G r a vit a t iona l c ons t a nt ( m e t e r s p e r s e c ond s q u a r e d)

� l = Liq uid de ns it y ( kilogr a m s p e r c u b i c m e t e r )

A

p r i l 15, 1999 D - 16Ap p e ndix D

T e c hnic a l Ba c kgr ound

LLF va lue s w e r e c a lc ula t e d f o r

a ll liq uids r e gula t e d unde r C AA s e c t ion 1 1 2 (r) an d are l i s t e d i n Ap p e ndix B

, Ex hib it B

- 2 , f o r

t o x i c liq uids a nd Ap p e ndix C

, Ex hib it C

- 3 , f o r

f

l a m m a b l e liq uids

.

F r o m t h e e q ua t ion f o r

liq uid r e le a s e r a t e f

r o m a hole in a t a nk a t a m b i e n t p r e s s u r e a nd t h e e q ua t ion

f o r

t h e LLF , t h e init ia l r e le a s e r a t e f

o r

a liq uid f r o m a t a nk unde r a t m o s p h e r ic p r e s s u r e c a n b e w r it t e n a s :



### QR L 

### � HA × LH × LLF (D -1 8 )

w h er e: QR L = Liq uid r e le a s e r a t e ( p ounds p e r m inut e )

HA = Hole a r e a ( s q u a r e inc he s )

LH = H e ight of liq uid a b ove hole ( inc he s )



### D. 7. 2 R el eas e s f r om P i pes

T h e e q ua t ion us e d t o e s t i m a t e r e le a s e s of liq uids f r o m p i p e s is t h e B e r noulli e q ua t ion. I t a s s u m e s

t h a t t h e de ns it y of t h e liq uid is c ons t a nt a nd doe s not a c c ount f o r

los s e s in ve loc it y due t o w a ll f r i c t ion. T h e

e q ua t ion f ollow s :



### � � �

� � ( P

a 

### P b 

### ) g ( Z

a 

### Z b 

### ) ( V b 2 

### V

a 2 

### ) (D -1 9 ) D g
c 

### 2 g
c

w h er e: P

a = P r e s s u r e a t p i p e inle t (Pas c a l s )

P

b = Pre s s u re at p i p e o u t l e t (Pas c a l s )

Z

a = H e ight a b ove da t u m p l a n e a t p i p e inle t ( m e t e r s )

Z

b = H e ight a b ove da t u m p l a n e a t p i p e r e le a s e ( m e t e r s )

g = G r a vit a t iona l a ccel er a t ion ( 9 .8 m e t e r s p e r s e c ond s q u a r e d)

g c = N e w t on' s la w p r op or t iona lit y f

a c t o r ( 1 .0 )

V

a = O p e r a t iona l ve loc it y ( m e t e r s p e r s e c ond)

V

b = R e l e a s e ve loc it y ( m e t e r s p e r s e c ond)

D = D e n s i t y of liq uid ( kilogr a m s p e r c u b i c m e t e r )

I s ola t ing V y i e lds : b



### � 2 g
c 

### ( P

a 

### P b 

### )

� � 2 g ( Z

a 

### � Z b 

### ) � V

a 2 

### (D -2 0 ) V

b 

### D

T o de ve lop t h e e q ua t ion p r e s e n t e d in t h e t e x t

, c onve r s ion f a c t o r s f o r

Englis h unit s a nd c ons t a nt s

w e r e inc or p o r a t e d a s f ollow s :

A

p r i l 15, 1999 D - 17Ap p e ndix D

T e c hnic a l Ba c kgr ound



### 2×6895×( P T 

### � 14. 7) × DF ×0. 033 V

b 

### � 197 � ( 2 ×9. 8 ×0. 3048×( Z

a 

### � Z b 

### ) � 0. 00508 2 

### × V

a 2 

### 16. 08 (D -2 1 )

w h er e: V b = R e l e a s e ve loc it y ( f e e t p e r m inut e )

1 9 7 = C onve r s ion f a c t o r f

o r

m e t e r s p e r s e c ond t o f e e t p e r m inut e 6895 = C onve r s ion f a c t o r f

o r

p s i t o P a s c a ls

P T = T o t a l pi pe pr e ssu r e ( psi )

14. 7 = A t m o sph e r i c pr e ssu r e ( psi )

1 6

. 0 8 = C onve r s ion f a c t o r f

o r

p ounds p e r c u b i c f oot t o kilogr a m s p e r c u b i c m e t e r
DF = D e n si ty f

a c to r ( 1/( 0. 033 D F ) = d e n s i t y i n p ounds p e r c u b i c f oot )

2 9

. 8 = G r a vit a t iona l a ccel er a t ion ( m e t e r s p e r s e c ond )

0. 3048 = C onve r s ion f a c t o r f

o r

f

e e t t o m e t e r s
Z - Z b = C ha nge in p i p e e l e v a t ion, inle t t o out le t ( f e e t )

a 0. 00508= C onve r s ion f a c t o r f

o r

f

e e t p e r m inut e t o m e t e r s p e r s e c ond

V = O p e r a t iona l ve loc it y ( f e e t p e r m inut e )

a



### D. 8 V apor Cl oud F i r e s

F a c to r s f o r

l e a k s f r o m ta n k s f o r

f

l a m m a bl e su bsta n c e s ( G F a n d L L F ) w e r e d e r i v e d a s d e sc r i be d f

o r

to xi c su bsta n c e s ( s e e a b o v e )

.

T h e e ndp oint f o r

e s t i m a t ing im p a c t dis t a nc e s f o r

va p o r c loud f i r e s of f

l a m m a b l e s u bsta n c e s i s th e low e r f

l a m m a b ilit y lim it ( L F L )

. T h e LF L is one of t h e e ndp oint s f o r

r e le a s e s of f

l a m m a b l e s u bsta n c e s

s p e c i fi e d i n t h e RMP Ru l e

. I t w a s c h o s e n t o p r ovide a r e a s ona b l e , b u t not ove r l y c ons e r va t ive , e s t i m a t ion of

t h e p o s s i b l e e x t e nt of a va p o r c loud f i r e

.



### D. 9 P ool F i r e s

A f a c t o r us e d f

o r

e s t i m a t ing t h e dis t a nc e t o a he a t r a dia t ion le ve l f r o m a p ool f i r e t h a t c ould c a us e

s e c ond de gr e e b u r n s f r o m a 4 0

- s e c ond e x p o s u r e w a s de ve lop e d b a s e d on e q ua t ions p r e s e n t e d in t h e AI C h E

doc um e n t

, G uide line s for E v aluating the C harac te ristic s of V apor C loud E x

plosions, F lash F ire s, and

BL EVEs a nd in t h e Ne t h e r la nds T N O doc um e n t

, M e thods for the D e te rm ination of P ossible D a m age to

P e ople and O bje c ts R e sulting from R e le ase s of H azardous M ate rials ( 1992)

. Th e A I C h E a n d TN O

doc um e n t s p r e s e n t a p oint

- s our c e m ode l t h a t a s s u m e s t h a t a s e le c t e d frac t ion of t h e he a t of c o m b us t ion is

e m i t t e d a s r a dia t ion in a ll dir e c t ions

. T h e r a dia t ion p e r unit a r e a r ecei v e d b y a t a r g et a t s o me d i s t a n ce f r o m

t h e p oint s our c e is give n b y :


### f m H � q � 4 � x c

2 a 

### (D -2 2 )

A

p r i l 15, 1999 D - 18Ap p e ndix D

T e c hnic a l Ba c kgr ound

w h er e: q = R a dia t ion p e r unit a r e a r e c e i v e d by th e r e c e pto r ( W a tts pe r squ a r e m e t e r )

m = R a t e of c o m b us t ion ( kilogr a m s p e r s e c ond)

� = A t m os p h e r ic t r a n s m is s ivit y a H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m ) f = Frac t ion of he a t of c o m b us t ion r a dia t e d

x = Dis t a nc e f

r o m p oint s our c e t o r ecep t o r ( met er s )

T h e frac t ion of c o m b us t ion e n e r gy dis s i p a t e d a s t h e r m a l r a dia t ion ( f in t h e e q ua t ion a b ove ) is

r e p o r t e d t o r a nge f

r o m 0

. 1 t o 0

. 4

. T o de ve lop f a c t o r s f o r

e s t i m a t ing dis t a nc e s f o r

p ool f i r e s , t his frac t ion w a s

a s s u m e d t o b e 0

. 4 f o r

a ll t h e r e gula t e d f l a m m a b l e s u bsta n c e s

. Th e h e a t r a d i a t ion le ve l ( q ) w a s a s s u m e d t o b e 5 kilow a tts ( 5

, 000 W a tts) pe r squ a r e m e t e r

. Th i s l e v e l i s r e po r t e d to c a u s e se c ond de gr e e b u r n s f r o m a 4 0

-

s e c ond e x p o s u r e

. O n e of t h e e ndp oint s f o r

r e le a s e s of f

l a m m a b l e s u bsta n c e s spe c i f i e d i n th e RMP Ru l e i s 5

kilow a tts pe r squ a r e m e t e r f

o r

40 se c onds

. I t w a s a s s u m e d t h a t p e op le w ould b e a b le t o e s c a p e f

r o m t h e he a t
in 4 0 s e c onds

. T h e a t m o s p h e r ic t r a n s m is s ivit y ( �
a ) w a s a ssu m e d e q u a l to o n e

.

F o r a p ool f i r e of a f l a m m a b l e s u bsta n c e w i th a b oiling p oint a b ove t h e a m b i e n t t e m p e r a t ur e , t h e

c o m b us t ion r a t e c a n b e e s t i m a t e d b y t h e f

ollow ing e m p ir ic a l e q ua t ion:



### 0. 0010 H A

c 

### m � H

v 

### � C
p 

### ( T b 

### � T

a 

### ) (D -2 3 )

w h er e: m = R a t e of c o m b us t ion ( kilogr a m s p e r s e c ond)

H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

H = H e a t of va p o r i z a t ion ( J oule s p e r kilogr a m )

v C = Liq uid he a t c a p a c i t y ( J oule s p e r kilogr a m

- d e g r e e K )
p A = P ool a r e a ( s q u a r e m e t e r s )

T

b = B oiling t e m p e r a t ur e ( K )

T = A mb i e n t t emp er a t u r e ( K )

a 0. 0010 = C o n sta n t

C o m b ining Eq ua t ions D- 2 2 a nd D- 2 3 ( a b ove )

, a nd a s s u m ing a he a t r a dia t ion le ve l of 5

, 000 W a tts

p e r s q u a r e m e t e r , give s t h e f

ollow ing e q ua t ion f o r

liq uid p ools of s u bsta n c e s w i th b oiling p oint s a b ove

a m b i en t t emp er a t u r e:



### 0. 0010 A

H

v 

### � C
p 

### ( T b 

### � T

a 

### ) (D -2 4 )

x � H 0. 4

c 

### 4 � q

or

A

p r i l 15, 1999 D - 19Ap p e ndix D

T e c hnic a l Ba c kgr ound



### 0. 0001 A

x � H

c 

### � 5, 000 � ( H

v 

### C
p 

### ( T b 

### � T

a 

### )) (D -2 5 )

w h er e: x = Dis t a nc e f

r o m p oint s our c e t o r ecep t o r ( met er s )

q = R a dia t ion p e r unit a r e a r e c e i v e d by th e r e c e pto r = 5, 000 W a tts pe r squ a r e

met er
H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m ) f = Frac t ion of he a t of c o m b us t ion r a dia t e d = 0

. 4

H

v = H e a t of va p o r i z a t ion ( J oule s p e r kilogr a m )

C

p = Liq uid he a t c a p a c i t y ( J oule s p e r kilogr a m

- d e g r e e K e lvin)

A = P ool a r e a ( s q u a r e m e t e r s )

T

b = B oiling t e m p e r a t ur e ( K )

T

a = A mb i e n t t emp er a t u r e ( K )

0. 0010 = C o n sta n t

F o r a p ool f i r e of a f l a m m a b l e s u bsta n c e w i th a b oiling p oint b e low t h e a m b i e n t t e m p e r a t ur e ( i .e ., liq ue f i e d ga s e s ) t h e c o m b us t ion r a t e c a n b e e s t i m a t e d b y t h e f

ollow ing e q ua t ion, b a s e d on t h e T N O

doc um e n t :



### 0. 0010 H A

c 

### m � (D -2 6 ) H

v

w h er e: m = R a t e of c o m b us t ion ( kilogr a m s p e r s e c ond)

H

v = H e a t of va p o r i z a t ion ( J oule s p e r kilogr a m )

H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

A = P ool a r e a ( s q u a r e m e t e r s )

0. 0010 = C o n sta n t

T h e n t h e e q ua t ion f o r

dis t a nc e a t w hic h t h e r a dia t ion r e c e i v e d e q u a l s 5, 000 W a tts pe r squ a r e m e t e r be c o m e s :



### 0. 0001 A

x � H (D -2 7 )

c 

### 5, 000 � H

v

w h er e: x = Dis t a nc e f

r o m p oint s our c e t o r ecep t o r ( met er s )

5

, 0 0 0 = R a dia t ion p e r unit a r e a r e c e i v e d by th e r e c e pto r ( W a tts pe r squ a r e m e t e r )

H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

H

v = H e a t of va p o r i z a t ion ( J oule s p e r kilogr a m )

A = P ool a r e a ( s q u a r e m e t e r s )

0. 0001 = D e r i v e d c o n sta n t ( s e e e q u a t ions D- 2 0 a nd D- 2 1 )

A

p r i l 15, 1999 D - 20Ap p e ndix D

T e c hnic a l Ba c kgr ound

A "P ool F i r e F a c t o r " (PFF) w a s c a l c u l a t e d fo r e a c h re gula t e d f l a m m a b l e liq uid a nd ga s ( t o b e a p p lie d

t o ga s e s liq ue f i e d b y r e f r ige r a t ion) t o a llow e s t i m a t ion of t h e dis t a nc e t o t h e he a t r a dia t ion le ve l t h a t w ould

le a d t o s e c ond de gr e e b u r n s

. F o r t h e de r iva t ion of t his f a c t o r , a m b i e n t t e m p e r a t ur e w a s a s s u m e d t o b e 298 K

o (2 5 C). O t h e r fac t o rs are d i s c u s s e d ab o v e

. T h e PFF fo r l i q uids w i t h b oiling p oint s a b ove a m b i e n t

t e m p e r a t ur e w a s de r ive d a s f ollow s :



### 0. 0001 PFF � H

c 

### �

� 5, 000 � [ H

v 

### C
p 

### ( T b 

### 298) ] (D -2 8 )

w h e r e : 5

, 0 0 0 = R a dia t ion p e r unit a r e a r e c e i v e d by th e r e c e pto r ( W a tts pe r squ a r e m e t e r )

H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

H

v = H e a t of va p o r i z a t ion ( J oule s p e r kilogr a m )

C

p = Liq uid he a t c a p a c i t y ( J oule s p e r kilogr a m

- d e g r e e K )

T

b = B oiling t e m p e r a t ur e ( K )

298 = A ssu m e d a m bi e n t te m p e r a t u r e ( K )

0. 0001 = D e r i v e d c o n sta n t ( s e e a b o v e )

F o r liq uids w i t h b oiling p oint s b e low a m b i e n t t e m p e r a t ur e , t h e PFF i s d e ri v e d as f ollow s :



### 0. 0001 PFF � H (D -2 9 )

c 

### 5, 000 � H

v

w h e r e : 5

, 0 0 0 = R a dia t ion p e r unit a r e a r e c e i v e d by th e r e c e pto r ( W a tts pe r squ a r e m e t e r )

H

c = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

H

v = H e a t of va p o r i z a t ion ( J oule s p e r kilogr a m )

0. 0001 = D e r i v e d c o n sta n t ( s e e a b o v e )

Dis t a nc e s w h e r e e x p o s e d p e op le c ould p o t e nt ia lly s u f f e r

s e c ond de gr e e b u r n s c a n b e e s t i m a t e d a s t h e
PFF m u l t i p l i e d b y t h e s q u are ro o t o f t h e p ool a r e a ( in s q u a r e f

e e t )

, a s dis c u s s e d in t h e t e x t

.



### D. 1 0 B LEVEs

R e f e r e nc e T a b l e 3 0

, t h e t a b l e of dis t a nc e s f o r

B LEVEs , w a s de ve lop e d b a s e d on e q ua t ions p r e s e n t e d

in t h e AI C hE doc um e n t

, G uide line s for E v aluating the C harac te ristic s of V apor C loud E x

plosions, F lash

F

ire s, and B L EVEs

. T h e Hy m e s p oint

- s our c e m ode l f o r

a f i r e b a ll, a s c i t e d in t h e AI C hE doc um e n t

, us e s t h e f ollow ing e q ua t ion f o r

t h e r a dia t ion r ecei v e d b y a r ecep t o r :



### 2. 2 �

a 

### R H

c 

### m f 0. 67



### q � (D -3 0 ) 4 � L 2

w h er e: q = R a dia t ion r e c e i v e d by th e r e c e pto r ( W a tts pe r squ a r e m e t e r )

m

f = M a s s of f

u e l in t h e f

i r e b a ll ( kg)

A

p r i l 15, 1999 D - 21Ap p e ndix D

T e c hnic a l Ba c kgr ound

�
a = A t m os p h e r ic t r a n s m is s ivit y
H = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

c R = Rad i a t i v e frac t ion of he a t of c o m b us t ion

L = D i s t a n ce f r o m f i r e b a l l cen t e r t o r ecep t o r ( met er s )

� = 3

. 1 4

Hy m e s ( a s c i t e d b y AI C hE) s ugge sts th e f

ollow ing va lue s f o r

R :

R = 0

. 3 f o r

ve s s e ls b u r s t ing b e low r e lie f va lve p r e s s u r e
R = 0

. 4 f o r

ve s s e ls b u r s t ing a t or a b ove r e lie f va lve p r e s s u r e

F o r de ve lop m e n t of R e f e r e nc e T a b l e 3 0

, t h e f

ollow ing c ons e r va t ive a s s u m p t ions w e r e m a de :

R = 0

. 4

�
a = 1

T h e e f f e c t s of r a dia nt he a t on a n e x p o s e d p e r s on de p e nd on b o t h t h e int e n s i t y of t h e r a dia t ion a nd t h e dur a t ion of t h e e x p o s u r e

. F o r de ve lop m e n t of t h e t a b l e of dis t a nc e s f o r

B LEVEs , it w a s a s s u m e d t h a t t h e

t i m e of e x p o s u r e w ould e q ua l t h e dur a t ion of t h e f

i r e b a ll. T h e AI C hE doc um e n t give s t h e f

ollow ing

e q ua t ions f o r

dur a t ion of a f i r e b a ll:



### t

c 

### � 0. 45 m f

1/ 3 

### fo r m f 

### < 30, 000 kg (D -3 1 )

an d



### t

c 

### � 2. 6 m f

1/ 6 

### fo r m f 

### > 30, 000 kg (D -3 2 )

w h er e: m f = Mas s o f fu e l (k g )

t

c = C om b u s t ion dur a t ion ( s e c onds )

Ac c o r ding t o s e ve r a l s our c e s ( e .g., Eis e n b e r g , e t a l

., V ulne rability M ode l, A Sim ulation Sy ste m for

A sse ssing D a m age R e sulting from M arine Spills ; M uda n, T h e r m al R adiation H azards from H y droc arbon

Pool F ire s ( c it ing K

. B u e t t n e r)), t h e e ffe c t s o f t h e r m a l rad i a t ion a r e ge ne r a lly p r op or t iona l t o r a dia t ion

int e n s i t y t o t h e f

our

- t hir ds p o w e r t i m e s t i m e of e x p o s u r e

. T hus , a t h e r m a l "dos e " c a n b e e s t i m a t e d us ing t h e f ollow ing e q ua t ion:



### Dos e � tq 4/ 3 

### (D -3 3 )

w h er e: t = Dur a t ion of e x p o s u r e ( s e c onds )

2 q = R a dia t ion int e n s i t y ( W a tts/m )

T h e t h e r m a l "dos e " t h a t c ould c a us e s e c ond- de gr e e b u r n s w a s e s t i m a t e d a s s u m ing 4 0 s e c onds a s t h e dur a t ion of e x p o s u r e a nd 5

, 000 W a tts/m 2 a s th e r a d i a t ion int e n s i t y

. T h e c o r r e s p onding dos e is 3

, 420, 000 ( W a tts/m ) 2 4 / 3

- se c ond.

A

p r i l 15, 1999 D - 22Ap p e ndix D

T e c hnic a l Ba c kgr ound

F o r e s t i m a t ing t h e dis t a nc e f

r o m a f i r e b a ll a t w hic h a r e c e p t o r m ight r e c e ive e nough t h e r m a l r a dia t ion

t o c a us e s e c ond de gr e e b u r n s , t h e dos e e s t i m a t e d a b ove w a s s u bsti tu te d i n t o th e e q u a t ion f o r

r a dia t ion

re c e i v e d fro m a fi re b a l l :

3 

### 3, 420, 000 4 

### (D -3 4 ) q � t

3/

4 

### 2. 2 �

a 

### R H

c 

### m f 0. 67 

### 3, 420, 000

� (D -3 5 )
t 4 � L 2



### 2. 2 �

a 

### R H

c 

### m f 0. 67 

### L � 3/ 4 

### (D -3 6 ) 3, 420, 000 4 � t

w h er e: L = D i s t a n ce f r o m f i r e b a l l cen t e r t o r ecep t o r ( met er s )

q = R a dia t ion r e c e i v e d by th e r e c e pto r ( W a tts pe r squ a r e m e t e r )

m

f = M a s s of f

u e l in t h e f

i r e b a ll ( kg)

� = A t m os p h e r ic t r a n s m is s ivit y ( a s s u m e d t o b e 1 )

a H = H e a t of c o m b us t ion ( J oule s p e r kilogr a m )

c R = Rad i a t i v e frac t ion of he a t of c o m b us t ion ( a s s u m e d t o b e 0

. 4 )

t = Dur a t ion of t h e f

i r e b a ll ( s e c onds ) ( e s t i m a t e d f r o m t h e e q ua t ions a b ove ) ;

a s s u m e d t o b e dur a t ion of e x p o s u r e

Eq ua t ion D- 3 6 w a s us e d t o de ve lop t h e r e f e r e nc e t a b l e f

o r

B LEVEs p r e s e n t e d in t h e t e x t ( R e f e r e nc e Ta bl e 30)

.



### D. 11 Al t e r n at ive Scenar io Anal ys is f o r Vapor Cl oud E x pl os ions

Ac c o r ding t o T

. A. K l e t z , in "Unc onf ine d Va p o r C loud Ex p los ions " ( Ele ve nt h Los s P r e ve nt ion

S y m p o s i u m , spo n s o r e d by A I C h E

, 1977)

, u n c o n f i n e d v a po r c loud e x p los ions a l m o s t a l w a y s r e s ult f r o m t h e

r e le a s e of f

l a s hing liq uids

. F o r t his r e a s on, t h e q u a n t i t y in t h e c loud f o r

t h e a l t e r n a t ive s c e n a r io va p o r c loud

e x p los ion in t his guida nc e is b a s e d on t h e frac t ion f l a s he d f r o m t h e r e le a s e of a f l a m m a b l e ga s liq ue f i e d unde r

p r e s s u r e

. T h e guida nc e p r ovide s a m e t hod t o e s t i m a t e t h e q u a n t i t y in t h e c loud f r o m t h e frac t ion f l a s he d int o

va p o r p lus t h e q u a n t i t y t h a t m ight b e c arri e d a long a s a e r o s ol. T h e r e c o m m e nda t ion t o us e t w ic e t h e q u a n t i t y f l a s he d a s t h e m a s s in t h e c loud ( s o long a s it doe s not e x ceed t h e t o t a l a m ount of f

l a m m a b l e s u bsta n c e

a v a ila b l e ) is b a s e d on t h e m e t hod r e c o m m e n d e d b y t h e U K H e al t h an d Safe t y E x e c u t i v e (H SE ), as c i t e d i n t h e AI C hE doc um e n t

, G uide line s for E v aluating the C harac te ristic s of V apor C loud E x

plosions, F lash F ire s, and B L EVEs

. T h e f

a c t o r of t w o is int e nde d t o a llow f

o r

s p r a y a nd a e r o s ol f o r m a t ion.

A

p r i l 15, 1999 D - 23Ap p e ndix D

T e c hnic a l Ba c kgr ound

T h e e q ua t ion f o r

t h e f

l a s h frac t ion, f o r

p o s s i b l e us e in f o r

t h e a l t e r n a t ive s c e n a r io a n a l y s is , is b a s e d

on t h e Ne t h e r la nds T N O doc um e n t

, M e thods for the C alc ulation of the P h y sic al E ffe c ts of the E s c ape of

D ange rous M ate rial ( 1980)

, C h a pte r 4, " S pr a y R e l e a s e

. " Th e f

ollow ing e q ua t ion is p r ovide d:



### T

b 

### T b 

### C l 

### T l 

### � X � X ln (D -3 7 )

vap
, a vap
, b 

### T l 

### h

v 

### T b

w h er e: X = W e ight frac t ion of va p o r a f t e r e x p a ns ion

v ap, a X

v ap, b = W e ight frac t ion of va p o r b e f o r e e x p a ns ion ( a s s u m e d t o b e 0 f o r

c a lc ula t ion

o f

t h e fl as h frac t ion)

T

b = B oiling t e m p e r a t ur e of ga s c o m p r e s s e d t o liq uid ( K )

T

l = T e m p e r a t ur e of s t o r e d ga s c o m p r e s s e d t o liq uid ( K )

C l = S p e c i f i c he a t of ga s c o m p r e s s e d t o liq uid ( J oule s / kilogr a m

- K )

h = H e a t of e v a p or a t ion of ga s c o m p r e s s e d t o liq uid ( J oule s / kilogr a m )

v

T o d e v e l o p a Fl as h Frac t ion F a c t o r (FFF) fo r u s e i n c o n s e q u e n c e an al y s i s , c o m p re s s e d g a s e s w e re

o a ssu m e d to be sto r e d a t 25 C ( 298 K ) ( e xc e pt i n c a se s w h e r e th e g a s c ould not b e liq ue f i e d a t t h a t

t e m p e r a t ur e )

. T h e e q ua t ion f o r FFF i s :



### T b 

### C l 

### 298 FFF � ln (D -3 8 ) h

v 

### T b

w h er e: T b = B oiling t e m p e r a t ur e of ga s c o m p r e s s e d t o liq uid ( K )

C l = S p e c i f i c he a t of ga s c o m p r e s s e d t o liq uid ( J oule s / kilogr a m

- K )

h = H e a t of e v a p or a t ion of ga s c o m p r e s s e d t o liq uid ( J oule s / kilogr a m )

v 2 9 8 = T e m p e r a t ur e of s t o r e d ga s c o m p r e s s e d t o liq uid ( K )

T h e r e c o m m e nda t ion t o us e a y i e ld f a c t o r of 0

. 0 3 f o r

t h e a l t e r n a t ive s c e n a r io a n a l y s is f o r

va p o r c loud

e x p los ions a l s o is b a s e d on t h e UK HS E m e t hod c i t e d b y AI C hE. Ac c o r ding t o t h e AI C hE doc um e n t

, t his

r e c o m m e nda t ion is b a s e d on s u r v e y s s how ing t h a n m o s t m a jor va p o r c loud e x p los ions ha ve de ve lop e d

be tw e e n 1 pe r c e n t a n d 3 pe r c e n t o f a v a i l a bl e e n e r g y

.

A

p r i l 15, 1999 D - 24

## AP P E NDI X E

WO RK S H EETS F O R O F F S ITE CO NS EQ UENCE ANALYS IS

Us in g th e M e th o d s in th is Gu idan c e

A

p r i l 15, 1999

### W O RK S H EET 1
WORS T- CAS E ANALYS I S F O R TOXI C GAS

1. S e l ect S cen ar i o ( def i ned by r u le f o r w o r s t

cas e as r e leas e of lar g es t quantity

over 10 minutes ) Guidanc e Ref e r e n c e

� I d en t i f y

t o x i c gas Nam e : CAS n u m b e r :

- - C h a pt er 2

S ect i o n 3. 1

� I d e n t i fy la r g e s t q u a n t it y in

la r g e s t v e s s e l o r p i p e lin e Quantity ( pounds ) :

� I d en t i f y

wo r s t

- case

me t e o r o l o g ic a l c o n d it io n s A t m o s p he r i c s t ability c l as s : F

Wi n d sp eed : 1. 5 m / s A m bient tem p er atur e : 25 C o



### R e lativ e hum idity : 50%

2. Det e r m in e Rel e as e Rat e

� E s t i m a t e r e l ease r a t e Quantity/10 min, except

gas es liquef i ed by

r

e f

r ige r ation in s o me c a s e s R e le as e r a te ( l bs /min):

W

ill r e le as e alw a y s take plac e in e n c l os ur e ?

(If y e s , g o t o n e x t s t e p ) S ect i o n 3. 1. 1

� Rev i se r e l ease r a t e t o

acco un t f o r passi v e m i t i g at i o n (e n c l o s u re ) Can rel e ase cau s e f a i l u re of en cl osu r e? ( I f y e s, use un m it i g at ed r e l ease r a t e )

Fact or t o accou n t f

o r en cl osu r e : 0. 55

M itigate d r

e le as e r a te ( l bs /min): S ect i o n 3. 1. 2

3. D e te r m ine D i s t anc e to the E ndpoint Spe c i f i e d by R u l e

� I d e n t i f y

e n d p o i n t E n dpoint ( m g/L) : E xhi bi

t B

- 1

� D e t e r m i n e g a s d e ns i t y C

ons ider conditions ( e

. g

. , liquef i ed under pr es s u r e ) Den s e : Neutr a lly buoyant : E xhi bi

t B

- 1

� Det e r m i n e si t e t o po gr aph y
R u r a l and ur ban def i ned by

ru l e Ru ra l : Ur ban : S ect i o n 2. 1

� Det e r m i n e appr o p r i at e

r e f e r e n ce t a b l e o f di st an ces Us e 10- minute tables Ref e ren ce t abl e u s ed ( number ) : C h a pt er 4

Ref e r e n c e T a b l es 1- 12

� F i n d di st an ce o n r e f e r e n c e

ta b l e R e leas e r a te/endpoint ( n eutr ally buoyant) :

Dis t ance to endpoint (m i ) : C h a pt er 4

Ref e r e n c e T a b l es 1- 12

A

p r i l 15, 1999 E - 1

### W O RK S H EET 2
WORS T- CAS E ANALYS I S F O R TOXI C LI QUI D

1. S e l ect S cen ar i o ( def i ned by r u le f o r w o r s t

cas e as r e leas e of lar g es t quantity to f

o r m an evapor ating pool) Guidanc e Ref e r e n c e

� I d en t i f y

t o x i c l i qui d

� I d en t i f y

co n cen t r at i o n f

o r

s o lu t i o n s o r mix t u r e s Nam e : CAS n u m b e r :

- - C

o nc e n tr ation in s o lution or m i xtur e ( w t %): C h a pt er 2

S ect i o n 3. 2

S e c t io n 3

. 2

. 4

f o r m i x t u re s

� I d e n t i fy la r g e s t q u a n t it y in

la r g e s t v e s s e l o r p i p e lin e Quantity ( pounds ) : Quantity of r e

gulate d s u bs tanc e in m i xtur e :

� I d en t i f y

wo r s t

- case

me t e o r o l o g ic a l c o n d it io n s A t m o s p he r i c s t ability c l as s : F

Wi n d sp eed : 1. 5 m / s A m bient tem p er atur e : 25 C o



### R e lativ e hum idity : 50%

2. Det e r m in e Rel e as e Rat e

� Det e r m i n e t e m p er at ur e o f

s p ille d liq u i d

M u s t be highes t maximum daily temper atur e or pr oces s temper atur e, or boiling point f

o r gas es liquef i ed by

r

e f

r ige r ation T e m p er atur e of liquid (C ) : o 

### S ect i o n 3. 2

S e c t io n 3

. 1

. 3

� Det e r m i n e appr o p r i at e l i qui d f act o r s f o r r e l ease r a t e

e s t ima t i o n LF A : LF B : DF : TC F : S ect i o n 3. 2,

E x h i b it s B- 2,

B

- 4

Sect i o n 3. 3,

E xhi bi

t B

- 3

fo r w a t e r

so l u t i o n s

E

s tim ate M axim u m P ool A r ea

� E s t ima t e ma x imu m p o o l

ar ea Spilled liquid f o r m s pool 1 cm deep M axim u m pool ar ea ( f

t ): 2 

### S e c t io n 3

. 2

. 3

E quat i o n 3- 6

A

p r i l 15, 1999 E - 2

### W O RK S H EET 2 ( c o n t i n u e d )

E

s tim ate P ool A r e a for Spill into Dike d A r e a

� E s t i m a t e di ked ar ea C

ons ider f

a ilur e of dikes or

over f

l ow of diked ar ea Diked ar ea ( f

t ): 2



### I

s diked ar ea s m aller than m axim u m ar ea?

____ ( I f n o , use m a x i m u m ar ea t o est i m a t e r e l ease r a t e )
Diked volum e ( f

t ): 3 

### Spille d v o lum e ( f

t ): 3



### I

s s p ille d v o lum e s m alle r than dike d v o lum e ?

___ (If n o , e s t i m a t e o v e r f l o w ) Overf l ow vol u m e ( f

t ): 3 

### Overf l ow area ( f

t ): 2 

### Sect i o n 3. 2. 3

� Ch o o s e po o l ar ea f o r r e l ease

r a te e s ti m a ti on
M a

xi mum area, di ked area,

or s u m of diked ar ea and

over f

l ow ar ea P ool ar ea ( f

t ): 2 

### S ect i o n 3. 2. 3

E

s tim ate R e leas e R a te f r

om P ool

� E s t i m a t e r e l ease r a t e f o r

un di ked po o l ( m ax i m u m po o l

ar ea)

B a s e d on quantity s p illed,

LF A or LF B

, and DF R e le as e r a te ( l bs /min): S ect i o n 3. 2. 2

Sect i o n 3. 2. 4 ( mix t u r e s )

E quat i o n 3- 3

o r 3- 4

� E s t i m a t e r e l ease r a t e f o r di

ked po o l ( u s e po o l ar ea fr o m p r e v io u s s e c t io n )

B a s e d on pool ar ea and LF A

or LF B R e le as e r a te ( l bs /min): S ect i o n 3. 2. 2

Sect i o n 3. 2. 4 ( mix t u r e s )

E quat i o n 3- 7

o r 3- 8

� Rev i se r e l ease r a t e f o r

r e le a s e in b u ild in g A

pply f a ctor to r e leas e r a te R e le as e r a te if outs ide ( l bs /min) ( U s e r e l eas e r a t e f o r un di ked o r di ked po o l )

Fact or t o accou n t f

o r en cl osu r e : 0. 1

Revi sed rel e a s e ra t e ( l bs /min): S ect i o n 3. 2. 3

E q u a t i o n s 3

- 9

, 3- 10

� Rev i se r e l ease r a t e f o r

t e m p er at ur e A

pply appr opr iate TC F

to
rel e a s e ra t e Revi sed rel e a s e ra t e ( l bs /min): S ect i o n 3. 2. 5

E quat i o n 3- 11

� E s t i m a t e dur at i o n o f r e l ease R e le as e dur a tion ( m in ): S ect i o n 3. 2. 2

E quat i o n 3- 5

A

p r i l 15, 1999 E - 3

### W O RK S H EET 2 ( c o n t i n u e d )

3. D e te r m ine D i s t anc e to the E ndpoint

� I d e n ti f y

e n d p o i n t
S

peci f

i ed by rul e E n dpoint ( m g /

L): E x h i b it B

- 2

� D e t e r m i n e va p o r d e ns it y Den s e : Neutr a lly buoyant : E xhi bi

t B

- 2

� Det e r m i n e si t e t o po gr aph y
R u r a l and ur ban def i ned by

ru l e Ru ra l : Ur ban : S ect i o n 2. 1

� Det e r m i n e appr o p r i at e

r e f e r e n ce t a b l e o f di st an ces
B a s e d on r e leas e dur ation,

vapor dens ity, topogr aphy Ref e ren ce t abl e u s ed ( number ) : C h a pt er 4

Ref e r e n c e T a b l es 1- 12

� F i n d di st an ce o n r e f e r e n c e

ta b l e R e leas e r a te/endpoint ( n eutr ally buoyant) : Dis t ance to endpoint ( m i): C h a pt er 4

Ref e r e n c e T a b l es 1- 12

A

p r i l 15, 1999 E - 4

### W O RK S H EET 3
WORS T- CAS E ANALYS I S F O R F L AM M A B LE S U B S TANCE

1. S e l ect S cen ar i o ( def i ned by r u le f o r w o r s t

cas e as vapor cloud explos i on of

lar g es t quantity) Guidanc e Ref e r e n c e

� I d en t i f y

f

l am m a b l e

s u bs t a nc e Nam e : CAS n u m b e r :

- - C h a pt er 2

S e c t i o n 3

. 1

� I d e n t i fy la r g e s t q u a n t it y in

la r g e s t v e s s e l o r p i p e lin e C

ons ider total quantity of f

l ammable s ubs tance, including non- r e gulated

s ubs tances in f l ammable

mi xt ures Quantity ( pounds ) :

2. D e te r m ine D i s t anc e to the yield f a ctor as s u med to be E ndpoint ( e ndpoint s p ecif i ed by the r u le as 1 ps i ov

10% f o r TN T- equivalent model) er pr es s u r e ;

� E s t i m a t e di s t an ce t o 1 ps i

usi n g Ref e r e n ce T a b l e
F i nd quantity, r e ad dis t ance f

r

om table Dis t ance to 1 ps i ( m i): C h a pt er 5

Ref e r e n c e Ta b l e 1 3

� A l t e r n at i v el y , est i m a t e di s t an ce t o 1 ps i us i n g equat i o n F o r pur e sub s t a n ce: He at of c o m b us tion ( kJ/ kg) : F o r m i x t u re : Heat of com b us tion of m a jor com ponent ( kJ/ kg) : Heats of com b us tion of other com ponents ( kJ/ kg) : , ,

Dis t ance to 1 ps i ( m i )

. Ch apt e r 5

A

ppen d i x C

. 1

A ppen d i x C

. 2

E xhi bi

t C

- 1

A

p r i l 15, 1999 E - 5

### W O RK S H EET 4
ALTERNATI V E S C ENARI O ANALYS I S F O R TOXI C GAS

1. S e l ect S cen ar i o G u i d an ce Ref e r e n c e

� I d en t i f y

t o x i c gas Nam e : CAS n u m b e r :

- - C h a pt er 6
Ch ap t e r 7

S ect i o n 7. 1

� I d en t i f y

co n d i t i o n s o f

s t or a g e or p r oc e s s i n g of tox i c

gas
Tr eat gas es liquef i ed by

r

e f

r iger ation as liquids N o n
- l i q u e f

i ed p r essu ri zed g a s : G

a s l i q u e f

i ed u n d er p r essu re : In t a n k : I

n pipeline : Oth e r ( d escri b e) :

� Dev e l o p al t e r n at i v e

scen ar i o

� Mo r e l i k el y

t h an wo r s t

case

� S h o u l d r each en dpo i n t

o ff s i t e D e scri b e scen a r i o :

� I d en t i f y

av er age

me t e o r o l o g ic a l c o n d it io n s A t m o s p he r i c s t ability c l as s : D

Wi n d sp eed : 3. 0 m / s A m bient tem p er atur e : 25 C o



### R e lativ e hum idity : 50%

2. Det e r m in e Rel e as e Rat e

� E s t i m a t e gas r e l ease r a t e f r o m h o l e i n t a n k ( c h o ked/

ma x imu m flo w ) fo r

� P r essur i zed gas

� Gas l i quef i ed un der

pr essur e r e l eased f r o m v a po r

space Hole ar e a ( i n ): 2



### T

a n k p r essu re ( p s i a ):
Tank te m p e r atur e ( K ):

GF : R e le as e r a te ( l bs /min): S ect i o n 7. 1. 1

E quat i o n 7- 1

E x h i b it B

- 1

� E s t i m a t e f l as h i n g l i qui d

r e l e a s e r a te f r om h o l e i n ta n k

� Gas l i quef i ed un der

pr essur e r e l eased f r o m li qui d

space Hole ar e a ( i n ): 2



### T

a n k p r essu re ( p s i g ):

DF : Liquid he ight abov e hole ( i n ):

R e le as e r a te ( l bs /min): S ect i o n 7. 1. 2

E q u a ti on 7

- 2

E x h i b it B

- 1

A

p r i l 15, 1999 E - 6

### W O RK S H EET 4 ( c o n t i n u e d )

� E s t i m a t e f l as h i n g l i qui d

r e l ease r a t e f r o m b r eak i n l o ng p i p e l i n e

� Gas l i quef i ed un der

p r e s s u r e c o mp le t e ly fillin g pi

pel i n e I n itial flow r a te ( l bs /min):

DF : I

n itial flow v e l oc ity ( f

t/min):

P i

p e p r essu re ( p s i ):

C

h ange in pipe elevation ( f

t):

C

r

os s
- s ectional pipe ar ea ( f

t ): 2



### R e le as e r a te ( l bs /min): S ect i o n s 7. 1. 1

an d 7. 2. 1

E xhi bi

t B

- 1

� E s t i m a t e r e l ease dur at i o n T i m e to s t op r e leas e ( m in ):

T

i m e to em pty tank or pipe ( m in ):

De fault r e le as e dur a tion : 60 m i n S ect i o n 7. 1. 1

� Rev i se r e l ease r a t e f o r

p a s s i v e mit ig a t io n ( e n c lo s u r e ) R e le as e r a te if outs ide ( l bs /min):

Fact or t o accou n t f

o r en cl osu r e : 0. 55

Revi sed rel e a s e ra t e ( l bs /min): S ect i o n 7. 1. 2

S e c t io n 3

. 1

. 2

� Rev i se r e l ease r a t e f o r

a c t iv e mit ig a t io n A c tiv e m itigation te c hnique us e d :

T

i m e to s t op r e leas e us ing active technique ( m in ):

F

r

ac tional r e le as e r a te r e duc tion by ac tiv e

te c hnique : Revi sed rel e a s e ra t e ( l b/min) :

� E s t i m a t e r e l ease dur at i o n ( m it i g at ed r e l ease) R e le as e dur a tion ( m in ): S ect i o n 7. 1. 2

� O t h e r re l e a s e ra t e

e s t ima t i o n R e le as e r a te ( l b/min) : M e thod of r e le as e r a te e s tim ation ( d escri b e) :

R e le as e dur a tion ( m in ):

3. D e te r m ine D i s t anc e to the E ndpoint

� I d e n ti f y

e n d p o i n t Speci f

i ed by rul e E n dpoint ( m g /

L): E x h i b it B

- 1

� D e t e r m i n e g a s d e ns it y C

ons ider conditions ( e

. g

. , liquef i ed under pr es s u r e ,

r

e f

r ige r ation) Den s e : Neutr a lly buoyant : E xhi bi

t B

- 1

� Det e r m i n e si t e t o po gr aph y
R u r a l and ur ban def i ned by

ru l e Ru ra l : Ur ban : S ect i o n 2. 1

A

p r i l 15, 1999 E - 7

### W O RK S H EET 4 ( c o n t i n u e d )

� Det e r m i n e appr o p r i at e

r e f e r e n ce t a b l e o f di st an ces
B a s e d on r e leas e dur ation,

vapor dens ity, and

topogr aphy Ref e ren ce t abl e u s ed ( number ) : C h a pt er 8

Ref e r e n c e T a b l es 14- 25

� F i n d di st an ce o n r e f e r e n c e

ta b l e R e leas e r a te/endpoint ( n eutr ally buoyant) : Dis t ance to endpoint ( m i): C h a pt er 8

Ref e r e n c e T a b l es 14- 25

A

p r i l 15, 1999 E - 8

### W O RK S H EET 5
ALTERNATI V E S C ENARI O ANALYS I S F O R TOXI C LI QUI D

1. S e l ect S cen ar i o G u i d an ce Ref e r e n c e

� I d en t i f y

t o x i c l i qui d I n clude

gas es liquef i ed by

r

e f

r ige r ation

� I d en t i f y

co n cen t r at i o n f

o r

s o lu t i o n s o r mix t u r e s Nam e : CAS n u m b e r :

- - C

o nc e n tr ation in s o lution or m i xtur e ( w t %): Ch ap t e r 6
Ch ap t e r 7

S ect i o n 7. 2

� I d en t i f y

co n d i t i o n s o f

s t or a g e or p r oc e s s i n g of tox i c l i qui d At m o sp h e ri c t a n k : P

r

essu ri zed t

a n k : P i

pe line : Oth e r ( d escri b e) :

� Dev e l o p al t e r n at i v e

scen ar i o

� Mo r e l i k el y

t h an wo r s t

case

� S h o u l d r each en dpo i n t

o ff s i t e D e scri b e scen a r i o :

� I d e n ti f y

m e te or ol og i c a l

c o n d it io n s A t m o s p he r i c s t ability c l as s : F

Wi n d sp eed : 3. 0 m / s A m bient tem p er atur e : 25 C o



### R e lativ e hum idity : 50%

2. Det e r m in e Rel e as e Rat e

De te r m ine L i quid R e le as e R a te and Quantity R e le as e d into P ool

� E s t i m a t e l i qui d r e l eas e r a t e fr o m h o le in a t mo s p h e r i c t a n k Hole ar e a ( i n ): 2



### LLF : Liquid he ight abov e hole ( i n ):

L i quid r e le as e r a te ( l bs /min): Sect i o n 7. 2. 1

E q u a t i o n 7

- 4

E xhi bi

t B

- 2

� E s t i m a t e l i qui d r e l eas e r a t e f r o m b r eak i n l o n g pi pel i n e I n itial flow r a te ( l bs /min):

DF : I

n itial flow v e l oc ity ( f

t/min):

P i

p e p r essu re ( p s i ):

C

h ange in pipe elevation ( f

t):

C

r

os s
- s ectional pipe ar ea ( f

t ): 2



### L i quid r e le as e r a te ( l bs /min): Sect i o n 7. 2. 1

E quat i o n s 7- 5

- 7- 7

E xhi bi

t B

- 2

� E s t i m a t e l i qui d r e l eas e dur at i o n T i m e to s t op r e leas e ( m in ):

T

i m e t o em pt

y t a n k t o l evel of h o l e ( m in ): S ect i o n 7. 2. 1

A

p r i l 15, 1999 E - 9

### W O RK S H EET 5 ( c o n t i n u e d )

� R e v i s e l i qui d r e l eas e d u r a t io n fo r a c t iv e mit ig a t io n A c tiv e m itigation te c hnique ( d escri b e) :

T

i m e to s t op r e leas e ( m in ): S ect i o n 7. 2. 2

� E s t i m a t e quan t i t y

o f l

i qui d

r e l eas ed i n t o po o l Liquid r e leas e r a te times
dur ation Quantity of liquid r e le as e d ( l b s ): S ect i o n s 7. 2. 1,

7. 2. 2, 7. 2. 3

Deter m ine P ool A r ea and E v apor ation R a te f r

om P ool

� Det e r m i n e t e m p er at ur e o f

s p ille d liq u i d T e m p er atur e of liquid ( C ): o 

### S ect i o n 7. 2. 3

� Det e r m i n e appr o p r i at e li qui d f act o r s f o r r e l ease r a t e

e s t i m a t i o n LF A : LF B : DF : TC F : S ect i o n s 7. 2. 3,

3. 2, an d

E xhi bi

t s B

- 2

, B- 4

S ect i o n 3. 3

a n d E xhi bi

t B

3 f o r wat e r

so l u t i o n s

E s t i ma t e M a x i mu m Po o l A r e a

� E s t ima t e ma x imu m p o o l

ar ea Spilled liquid f o r m s pool 1 cm deep M axim u m pool ar ea ( f

t ): 2 

### S e c t io n 7

. 2

. 3

, 3. 2. 3 E quat i o n 3- 6

E s tim a te P o o l A r e a f o r Spil l into D i k e d A r e a

� E s t i m a t e di ked ar ea C

ons ide r pos s i bility of f

a ilur e of

dikes or over f

l ow of diked

ar ea Diked ar ea ( f

t ): 2



### I

s diked ar ea s m aller than m axim u m ar ea?

____ ( I f n o , use m a x i m u m ar ea t o est i m a t e r e l ease r a t e )
Diked volum e ( f

t ): 3 

### Spille d v o lum e ( f

t ): 3



### I

s s p ille d v o lum e s m alle r than dike d v o lum e ?

___ (If n o , e s t i m a t e o v e r f l o w ) Overf l ow vol u m e ( f

t ): 3 

### Overf l ow area ( f

t ): 2 

### Sect i o n 7. 2. 3,

3. 2. 3

� Ch o o s e po o l ar ea f o r

ev apo r at i o n r a t e est i m a t i o n
M a

xi mum area, di ked area,

or s u m of diked ar ea and

over f

l ow ar ea P ool ar ea ( f

t ): 2 

### S ect i o n 7. 2. 3,

3. 2. 3

A

p r i l 15, 1999 E - 1 0

### W O RK S H EET 5 ( c o n t i n u e d )

E s t i m a t e Rel e as e Rat e f r om P ool

� E s t i m a t e r e l ease r a t e f o r

un di ked po o l

B a s e d on quantity s p illed,

LF A or LF B

, and DF R e le as e r a te ( l bs /min): S ect i o n 7. 2 3

Sect i o n 3. 2. 4 ( mix t u r e s )

E quat i o n 7- 8

o r 7- 9

� E s t i m a t e r e l ease r a t e f o r di

ked po o l ( u s e po o l ar ea f r o m pr ev i o us s ect i o n )

B a s e d on pool ar ea and LF A

or LF B R e le as e r a te ( l bs /min): S ect i o n s 7. 2. 3,

3. 2. 2

Sect i o n 3. 2. 4 ( mix t u r e s )

E quat i o n 7- 10

o r 7- 11

� Rev i se r e l ease r a t e f o r

t e m p er at ur e A

pply appr opr iate TC F

to
rel e a s e ra t e Revi sed rel e a s e ra t e ( l bs /min): S ect i o n s 7. 2. 3,

3

. 2

. 5

E quat i o n 3- 11

� Rev i se r e l ease r a t e f o r

r e le a s e in b u ild in g A

pply f a ctor to r e leas e r a te R e le as e r a te if outs ide ( l bs /min):

Fact or t o accou n t f

o r en cl osu r e : 0. 05

Revi sed rel e a s e ra t e ( l bs /min): S ect i o n s 7. 2. 3,

3

. 2

. 3

� Rev i se r e l ease r a t e f o r

a c t iv e mit ig a t io n t e c h n i q u e A c tiv e m itigation te c hnique us e d :

F

r

ac tional r e le as e r a te r e duc tion by ac tiv e

te c hnique : Revi sed rel e a s e ra t e ( l b/min) : S ect i o n 7. 2. 3

� Co m p ar e l i qui d r e l ease r a t e

an d po o l ev apo r at i o n r a t e

� Ch o o s e sm al l e r r e l ease r a t e

as r e l ease r a t e f o r an al y s i s R e le as e r a te ( l b/min) : S ect i o n 7. 2. 3

3. D e te r m ine D i s t anc e to the E ndpoint

� I d e n ti f y

e n d p o i n t
S

peci f

i ed by rul e E n dpoint ( m g /

L): E x h i b it B

- 2

� D e t e r m i n e va p o r d e ns it y Den s e : Neutr a lly buoyant : E xhi bi

t B

- 2

� Det e r m i n e si t e t o po gr aph y
R u r a l and ur ban def i ned by

ru l e Ru ra l : Ur ban : S ect i o n 2. 1

A

p r i l 15, 1999 E - 1 1

### W O RK S H EET 5 ( c o n t i n u e d )

� Det e r m i n e appr o p r i at e

r e f e r e n ce t a b l e o f di st an ces
B a s e d on r e leas e dur ation,

vapor dens ity, and

topogr aphy Ref e ren ce t abl e u s ed ( number ) : C h a pt er 8

Ref e r e n c e T a b l es 14- 25

� F i n d di st an ce o n r e f e r e n c e

ta b l e R e leas e r a te/endpoint ( n eutr ally buoyant) : Dis t ance to endpoint ( m i): C h a pt er 8

Ref e r e n c e T a b l es 14- 25

A

p r i l 15, 1999 E - 1 2

### W O RK S H EET 6
ALTERNATI V E S C ENARI O ANALYS I S F O R F L AM M A B LE S U B S TANCE

1. S e l ect S cen ar i o G u i d an ce Ref e r e n c e

� I d en t i f y

f

l am m a b l e

s u bs t a nc e Nam e : CAS n u m b e r :

- - C h a pt er 6

� I d en t i f y

co n d i t i o n s o f

s t or a g e or p r oc e s s i n g of

f l a m m a bl e s u bs t a nc e

Tr eat gas es liquef i ed by

r

e f

r iger ation as liquids N o n
- l i q u e f

i ed p r essu ri zed g a s : G

a s l i q u e f

i ed u n d er p r essu re : Gas lique fie d by r e fr ige r ation : L i q u i d

u n d er a t m o sp h e ri c p r essu re : L i q u i d

u n d er p r essu re g r ea t e r t h a n a t m o sp h e ri c : Oth e r ( d escri b e) :

� I d en t i f y

appr o p r i at e

scen ar i o

� V a p o r c l o u d f i re

� P o o l f

i re

� B L EV E/ f i re b a l l

� Vapo r cl o ud ex pl o s i o n

� O t h e r (n o t c o v e re d b y OCA Gui d an ce) ( d escri b e) : A lter n ative s cenar io/type of f

i r

e or explos ion

2. Det e r m in e Rel e as e Rat e

Deter m ine R e leas e R a te f o r V apor C l oud F i r

e

� F o r gas r e l eases an d

f l ash i n g l i qui d r e l eases, see Wo rksh eet 4 R e le as e r a te ( l bs /min): S ect i o n 9. 1

S ect i o n 7. 1

E quat i o n s 7- 1,

7- 2, 7- 3

E xhi bi

t C

- 2

� F o r l i qui d r e l eases ( n o n

f l a s hi ng )

, see W o rksheet 5 L i quid r e le as e r a te ( l bs /min):

L i quid r e le as e dur a tion ( m in ): Quantity in pool ( l b s ):

R e le as e r a te to air ( l bs /min): S ect i o n 9. 2

S ect i o n 7. 2

E quat i o n s 7- 4

- 7- 12

E xhi bi

t C

- 3

Deter m ine P ool A r ea f o r P ool F i r

e

E s t i m a t e po o l ar ea: See

Wo rksh eet 5 Quantity in pool ( l b s ):

P ool ar ea ( f

t ): 2 

### Sect i o n s 10. 2

S ect i o n 7. 2

E xhi bi

t s C

- 2

, C- 3

A

p r i l 15, 1999 E - 1 3

### W O RK S H EET 6 ( c o n t i n u e d )

De te r m ine Quantity for B L E V E

D e t e r min e q u a n t it y in t a n k Quantity ( l b s ): S e c t io n 1 0

. 3

Deter m ine Quantity f o r V apor C l oud E xplos ion

D e t e r min e q u a n t it y in t a n k Quantity ( l b s ): S e c t io n 1 0

. 4

3. D e te r m ine D i s t anc e to the E ndpoint

� I d en t i f y

en dpo i n t sui t ab l e f o r scen ar i o

� L F L

� 5 kW /m f o r 40 2



### seco n d s

� 1 ps i o v er pr es s u r e E n dpoint : Ch apt e r 6

E x h i b i t s C- 2,

C -3

Deter m ine Dis t ance to L F L f o r V apor C l oud F i r

e

� D e t e r m i n e va p o r d e ns it y Den s e : Neutr a lly buoyant : E xhi bi

t B

- 2

� Det e r m i n e si t e t o po gr aph y
R u r a l and ur ban def i ned by

ru l e Ru ra l : Ur ban : S ect i o n 2. 1

� Det e r m i n e appr o p r i at e

r e f e r e n ce t a b l e o f di st an ces
B a s e d on vapor dens ity and

topogr aphy Ref e ren ce t abl e u s ed ( number ) : S ect i o n 10. 1

Ref e r e n c e T a b l es 26- 29

� F i n d di st an ce o n r e f e r e n c e

ta b l e R e leas e r a te/endpoint ( n eutr ally buoyant) : Di st

an ce t o L F L ( m i): S ect i o n 10. 1

Ref e r e n c e T a b l es 26- 29

Deter m ine Dis t ance to Heat R adiation E n dpoint f o r P ool F i r

e

� Cal c ul at e di st an ce t o 5

kW /m 2 

### PF F : P ool ar ea ( f

t ): 2



### Dis t an ce ( f

t): S ect i o n 10. 2

E quat i o n 10- 1

A

p r i l 15, 1999 E - 1 4

### W O RK S H EET 6 ( c o n t i n u e d )

Deter m ine Dis t ance to Heat R adiation E n dpoint f o r B L E V E

Det e r m i n e di st an ce f o r

r a d i a t io n fr o m fir e b a ll equi v a l e n t t o 5 kW /m f o r 40 2



### seco n d s Quantity ( l b s ):

Dis t an ce ( m i): S ect i o n 10. 3

R e fe r e n c e T a b l e 30

Deter m ine Dis t ance to Over pr es s u r e E n dpoint F o r V apor C l oud E xplos ion

Det e r m i n e di st an ce t o 1 psi Quantity in cloud can be

les s than total quantity

Y

i eld f a ctor can be les s than 10% FFF : Quantity flas he d : Y

i el d f a ct or : Dis t ance to 1 ps i ( m i): S ect i o n 10. 4

E xhi bi

t C

- 2

Ref e r e n c e Ta b l e 1 3

A

p r i l 15, 1999 E - 1 5

## AP P E NDI X F

CHEM I CAL ACCI DENT P R EVENTI ON P R OVI S I O NS

As co dif i ed at 40 CF R part 68 as o f Ju ly 1, 1998VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00032 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T Pt. 67, App. A

local agent, any noncompliance penalties owed by the source owner or operator shall be paid to the State or local agent.

A PPENDIX A TO P ART 67—T ECHNICAL S UPPORT D OCUMENT

N OTE : EPA will make copies of appendix A available from: Director, Stationary Source Compliance Division, EN–341, 401 M Street, SW., Washington, DC 20460.

[54 FR 25259, June 20, 1989]

A PPENDIX B TO P ART 67—I NSTRUCTION M ANUAL

N OTE : EPA will make copies of appendix B available from: Director, Stationary Source Compliance Division, EN–341, 401 M Street, SW., Washington, DC 20460.

[54 FR 25259, June 20, 1989]

A PPENDIX C TO P ART 67—C OMPUTER P ROGRAM

N OTE : EPA will make copies of appendix C available from: Director, Stationary Source Compliance Division, EN–341, 401 M Street, SW., Washington, DC 20460.

[54 FR 25259, June 20, 1989]

PART 68—CHEMICAL ACCIDENT PREVENTION PROVISIONS

Subpart A—General

Sec.
68.1 Scope.
68.2 Stayed provisions.
68.3 Definitions.
68.10 Applicability.
68.12 General requirements.
68.15 Management.

Subpart B—Hazard Assessment

68.20 Applicability.
68.22 Offsite consequence analysis parameters. 68.25 Worst-case release scenario analysis.
68.28 Alternative release scenario analysis.
68.30 Defining offsite impacts—population.
68.33 Defining offsite impacts—environment. 68.36 Review and update.
68.39 Documentation.
68.42 Five-year accident history.

Subpart C—Program 2 Prevention Program

68.48 Safety information.
68.50 Hazard review.
68.52 Operating procedures. 40 CFR Ch. I (7–1–98 Edition)

68.54 Training.

68.56 Maintenance.

68.58 Compliance audits.

68.60 Incident investigation.

Subpart D—Program 3 Prevention Program

68.65 Process safety information.

68.67 Process hazard analysis.

68.69 Operating procedures.

68.71 Training.

68.73 Mechanical integrity.

68.75 Management of change.

68.77 Pre-startup review.

68.79 Compliance audits.

68.81 Incident investigation.

68.83 Employee participation.

68.85 Hot work permit.

68.87 Contractors.

Subpart E—Emergency Response

68.90 Applicability.

68.95 Emergency response program.

Subpart F—Regulated Substances for
Accidental Release Prevention

68.100 Purpose.

68.115 Threshold determination.

68.120 Petition process.

68.125 Exemptions.

68.130 List of substances.

Subpart G—Risk Management Plan

68.150 Submission.

68.155 Executive summary.

68.160 Registration.

68.165 Offsite consequence analysis.

68.168 Five-year accident history.

68.170 Prevention program/Program 2.

68.175 Prevention program/Program 3.

68.180 Emergency response program.

68.185 Certification.

68.190 Updates.

Subpart H—Other Requirements

68.200 Recordkeeping.

68.210 Availability of information to the public.

68.215 Permit content and air permittingauthority or designated agency requirements.
68.220 Audits.

A PPENDIX A TO P ART 68—T ABLE OF T OXIC E NDPOINTS

A UTHORITY : 42 U.S.C. 7412(r), 7601(a)(1),
7661–7661f.

S OURCE : 59 FR 4493, Jan. 31, 1994, unless
otherwise noted.

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Subpart A—General

§ 68.1 Scope.

This part sets forth the list of regulated substances and thresholds, the petition process for adding or deletingsubstances to the list of regulated substances, the requirements for owners oroperators of stationary sources concerning the prevention of accidentalreleases, and the State accidental release prevention programs approvedunder section 112(r). The list of substances, threshold quantities, and accident prevention regulations promulgated under this part do not limit in any way the general duty provisions under section 112(r)(1).

§ 68.2 Stayed provisions.

(a) Notwithstanding any other provision of this part, the effectiveness of the following provisions is stayed from March 2, 1994 to December 22, 1997.

(1) In Sec. 68.3, the definition of ‘‘stationary source,’’ to the extent thatsuch definition includes naturally occurring hydrocarbon reservoirs or transportation subject to oversight or regulation under a state natural gas or hazardous liquid program for which the state has in effect a certification to DOT under 49 U.S.C. 60105;

(2) Section 68.115(b)(2) of this part, to the extent that such provision requiresan owner or operator to treat as a regulated flammable substance:

(i) Gasoline, when in distribution orrelated storage for use as fuel for internal combustion engines;

(ii) Naturally occurring hydrocarbonmixtures prior to entry into a petroleum refining process unit or a naturalgas processing plant. Naturally occurring hydrocarbon mixtures include any of the following: condensate, crude oil, field gas, and produced water, each as defined in paragraph (b) of this section;

(iii) Other mixtures that contain a regulated flammable substance andthat do not have a National Fire Protection Association flammability hazard rating of 4, the definition of which is in the NFPA 704, Standard Systemfor the Identification of the Fire Hazards of Materials, National Fire Protection Association, Quincy, MA, 1990, available from the National Fire Pro­ § 68.2

tection Association, 1 Batterymarch Park, Quincy, MA 02269–9101; and

(3) Section 68.130(a). (b) From March 2, 1994 to December 22, 1997, the following definitions shall apply to the stayed provisions described in paragraph (a) of this section:

Condensate means hydrocarbon liquidseparated from natural gas that condenses because of changes in temperature, pressure, or both, and remains liquid at standard conditions.

Crude oil means any naturally occurring, unrefined petroleum liquid.

Field gas means gas extracted from a production well before the gas enters a natural gas processing plant.

Natural gas processing plant meansany processing site engaged in the extraction of natural gas liquids from field gas, fractionation of natural gas liquids to natural gas products, or both. A separator, dehydration unit,heater treater, sweetening unit, compressor, or similar equipment shall notbe considered a ‘‘processing site’’ unless such equipment is physically located within a natural gas processing plant (gas plant) site.

Petroleum refining process unit means a process unit used in an establishmentprimarily engaged in petroleum refining as defined in the Standard Industrial Classification code for petroleumrefining (2911) and used for the following: Producing transportation fuels (such as gasoline, diesel fuels, and jet fuels), heating fuels (such as kerosene,fuel gas distillate, and fuel oils), or lubricants; separating petroleum; or separating, cracking, reacting, or reforming intermediate petroleum streams. Examples of such units include, but are not limited to, petroleum based solvent
units, alkylation units, catalytic hydrotreating, catalytic hydrorefining,catalytic hydrocracking, catalytic reforming, catalytic cracking, crude distillation, lube oil processing, hydrogenproduction, isomerization, polymerization, thermal processes, and blending,sweetening, and treating processes. Petroleum refining process units include sulfur plants.

Produced water means water extracted from the earth from an oil or natural gas production well, or that is

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separated from oil or natural gas after

extraction.

[59 FR 4493, Jan. 31, 1994, as amended at 61 FR 31731, June 20, 1996]

§ 68.3 Definitions.

For the purposes of this part:
Accidental release means an unanticipated emission of a regulated substance or other extremely hazardous substance into the ambient air from a stationary source.

Act means the Clean Air Act as amended (42 U.S.C. 7401 et seq .)

Administrative controls mean written procedural mechanisms used for hazard control.

Administrator means the administrator of the U.S. Environmental Protection Agency.

AIChE/CCPS means the American Institute of Chemical Engineers/Center for Chemical Process Safety.

API means the American Petroleum
Institute.

Article means a manufactured item, as defined under 29 CFR 1910.1200(b),that is formed to a specific shape or design during manufacture, that has end use functions dependent in whole or in part upon the shape or design during end use, and that does not release orotherwise result in exposure to a regulated substance under normal conditions of processing and use.

ASME means the American Society of Mechanical Engineers.

CAS means the Chemical Abstracts
Service.

Catastrophic release means a majoruncontrolled emission, fire, or explosion, involving one or more regulated substances that presents imminent and substantial endangerment to public health and the environment.

Classified information means ‘‘classified information’’ as defined in the Classified Information Procedures Act, 18 U.S.C. App. 3, section 1(a) as ‘‘any
information or material that has beendetermined by the United States Government pursuant to an executive order, statute, or regulation, to requireprotection against unauthorized disclosure for reasons of national security.’’

Condensate means hydrocarbon liquidseparated from natural gas that condenses due to changes in temperature, 40 CFR Ch. I (7–1–98 Edition)

pressure, or both, and remains liquid at
standard conditions.

Covered process means a process that has a regulated substance present inmore than a threshold quantity as determined under § 68.115.

Crude oil means any naturally occurring, unrefined petroleum liquid.

Designated agency means the state, local, or Federal agency designated by
the state under the provisions of § 68.215(d) .

DOT means the United States Department of Transportation.

Environmental receptor means natural areas such as national or state parks,forests, or monuments; officially designated wildlife sanctuaries, preserves,refuges, or areas; and Federal wilderness areas, that could be exposed atany time to toxic concentrations, radiant heat, or overpressure greater than or equal to the endpoints provided in § 68.22(a) , as a result of an accidental
release and that can be identified on local U. S. Geological Survey maps.

Field gas means gas extracted from a production well before the gas enters a natural gas processing plant.

Hot work means work involving electric or gas welding, cutting, brazing, orsimilar flame or spark-producing operations.

Implementing agency means the state or local agency that obtains delegation for an accidental release prevention program under subpart E, 40 CFR part
63. The implementing agency may, but is not required to, be the state or local air permitting agency. If no state or local agency is granted delegation, EPA will be the implementing agency for that state.

Injury means any effect on a humanthat results either from direct exposure to toxic concentrations; radiant heat; or overpressures from accidental releases or from the direct consequences of a vapor cloud explosion (such as flying glass, debris, and other projectiles) from an accidental release and that requires medical treatment or hospitalization.

Major change means introduction of anew process, process equipment, or regulated substance, an alteration of process chemistry that results in any change to safe operating limits, or

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other alteration that introduces a new hazard.

Mechanical integrity means the process of ensuring that process equipment is fabricated from the proper materialsof construction and is properly installed, maintained, and replaced to prevent failures and accidental releases.

Medical treatment means treatment, other than first aid, administered by a physician or registered professional personnel under standing orders from a physician.

Mitigation or mitigation system means specific activities, technologies, orequipment designed or deployed to capture or control substances upon loss of containment to minimize exposure of the public or the environment. Passive mitigation means equipment, devices, or technologies that function without human, mechanical, or other energyinput. Active mitigation means equipment, devices, or technologies thatneed human, mechanical, or other energy input to function.

NFPA means the National Fire Protection Association.

Natural gas processing plant (gas plant) means any processing site engaged in the extraction of natural gas liquids from field gas, fractionation of mixednatural gas liquids to natural gas products, or both, classified as North American Industrial Classification System(NAICS) code 211112 (previously Standard Industrial Classification (SIC) code 1321).

Offsite means areas beyond the property boundary of the stationary source,and areas within the property boundary to which the public has routine and unrestricted access during or outside business hours.

OSHA means the U.S. Occupational Safety and Health Administration. Owner or operator means any person who owns, leases, operates, controls, or supervises a stationary source.

Petroleum refining process unit means a process unit used in an establishmentprimarily engaged in petroleum refining as defined in NAICS code 32411 for petroleum refining (formerly SIC code2911) and used for the following: Producing transportation fuels (such as gasoline, diesel fuels, and jet fuels), heating fuels (such as kerosene, fuel § 68.3

gas distillate, and fuel oils), or lubricants; Separating petroleum; or Separating, cracking, reacting, or reforming intermediate petroleum streams. Examples of such units include, but are not limited to, petroleum based solvent units, alkylation units, catalytic hydrotreating, catalytic hydrorefining,catalytic hydrocracking, catalytic reforming, catalytic cracking, crude distillation, lube oil processing, hydrogenproduction, isomerization, polymerization, thermal processes, and blending,sweetening, and treating processes. Petroleum refining process units include sulfur plants.

Population means the public.

Process means any activity involving a regulated substance including any use, storage, manufacturing, handling,

or on-site movement of such substances, or combination of these activities. For the purposes of this definition, any group of vessels that are interconnected, or separate vessels that are located such that a regulatedsubstance could be involved in a potential release, shall be considered a single process.

Produced water means water extracted from the earth from an oil or natural gas production well, or that is separated from oil or natural gas after

extraction.

Public means any person except employees or contractors at the stationary source.

Public receptor means offsite residences, institutions (e.g., schools, hospitals), industrial, commercial, and office buildings, parks, or recreationalareas inhabited or occupied by the public at any time without restriction by the stationary source where members of the public could be exposed to toxicconcentrations, radiant heat, or overpressure, as a result of an accidental release.

Regulated substance is any substance listed pursuant to section 112(r)(3) of the Clean Air Act as amended, in § 68.130.

Replacement in kind means a replacement that satisfies the design specifications.

RMP means the risk management plan required under subpart G of this part.

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SIC means Standard Industrial Classification.

Stationary source means any buildings, structures, equipment, installations, or substance emitting stationaryactivities which belong to the same industrial group, which are located on

one or more contiguous properties, which are under the control of the same person (or persons under common control), and from which an accidentalrelease may occur. The term stationary source does not apply to transportation, including storage incident totransportation, of any regulated substance or any other extremely hazardous substance under the provisions of this part. A stationary source includes transportation containers used for storage not incident to transportation
and transportation containers connected to equipment at a stationarysource for loading or unloading. Transportation includes, but is not limited to, transportation subject to oversight or regulation under 49 CFR parts 192, 193, or 195, or a state natural gas or hazardous liquid program for which the state has in effect a certification to DOT under 49 U.S.C. section 60105. Astationary source does not include naturally occurring hydrocarbon reservoirs. Properties shall not be considered contiguous solely because of a railroad or pipeline right-of-way.

Threshold quantity means the quantity specified for regulated substances pursuant to section 112(r)(5) of the Clean Air Act as amended, listed in § 68.130 and determined to be present at a stationary source as specified in § 68.115 of this part.

Typical meteorological conditions means the temperature, wind speed, cloud cover, and atmospheric stability class, prevailing at the site based on data gathered at or near the site or from a local meteorological station.

Vessel means any reactor, tank, drum, barrel, cylinder, vat, kettle, boiler, pipe, hose, or other container.

Worst-case release means the release of the largest quantity of a regulated substance from a vessel or process linefailure that results in the greatest distance to an endpoint defined in § 68.22(a).

[59 FR 4493, Jan. 31, 1994, as amended at 61 FR 31717, June 20, 1996; 63 FR 644, Jan. 6, 1998] 40 CFR Ch. I (7–1–98 Edition)

§ 68.10 Applicability.

(a) An owner or operator of a stationary source that has more than athreshold quantity of a regulated substance in a process, as determined under § 68.115, shall comply with the requirements of this part no later than the latest of the following dates:

(1) June 21, 1999; (2) Three years after the date on which a regulated substance is first listed under § 68.130; or

(3) The date on which a regulated
substance is first present above a threshold quantity in a process.

(b) Program 1 eligibility requirements. A covered process is eligible for Program 1 requirements as provided in § 68.12(b) if it meets all of the following requirements:

(1) For the five years prior to the submission of an RMP, the process hasnot had an accidental release of a regulated substance where exposure to thesubstance, its reaction products, overpressure generated by an explosion involving the substance, or radiant heatgenerated by a fire involving the substance led to any of the following offsite:

(i) Death; (ii) Injury; or (iii) Response or restoration activities for an exposure of an environmental receptor;

(2) The distance to a toxic or flammable endpoint for a worst-case release assessment conducted under Subpart B and § 68.25 is less than the distance to

any public receptor, as defined in § 68.30; and

(3) Emergency response procedures
have been coordinated between the stationary source and local emergency planning and response organizations.

(c) Program 2 eligibility requirements. A covered process is subject to Program 2 requirements if it does notmeet the eligibility requirements of either paragraph (b) or paragraph (d) of
this section.

(d) Program 3 eligibility requirements. A covered process is subject to Program 3 if the process does not meet the requirements of paragraph (b) ofthis section, and if either of the following conditions is met:

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(1) The process is in SIC code 2611, 2812, 2819, 2821, 2865, 2869, 2873, 2879, or 2911; or

(2) The process is subject to the
OSHA process safety management standard, 29 CFR 1910.119.

(e) If at any time a covered process no longer meets the eligibility criteriaof its Program level, the owner or operator shall comply with the requirements of the new Program level that applies to the process and update the RMP as provided in § 68.190.

(f) The provisions of this part shall not apply to an Outer Continental Shelf (‘‘OCS’’) source, as defined in 40
CFR 55.2.

[61 FR 31717, June 20, 1996, as amended at 63 FR 645, Jan. 6, 1998]

§ 68.12 General requirements.

(a) General requirements. The owneror operator of a stationary source subject to this part shall submit a single RMP, as provided in §§ 68.150 to 68.185. The RMP shall include a registration that reflects all covered processes.

(b) Program 1 requirements. In addition to meeting the requirements of paragraph (a) of this section, the owner or operator of a stationary source witha process eligible for Program 1, as provided in § 68.10(b), shall:

(1) Analyze the worst-case release scenario for the process(es), as provided in § 68.25; document that the nearest public receptor is beyond the distanceto a toxic or flammable endpoint defined in § 68.22(a); and submit in the
RMP the worst-case release scenario as provided in § 68.165;

(2) Complete the five-year accident history for the process as provided in § 68.42 of this part and submit it in the RMP as provided in § 68.168;

(3) Ensure that response actions have been coordinated with local emergency planning and response agencies; and

(4) Certify in the RMP the following: ‘‘Based on the criteria in 40 CFR 68.10, the distance to the specified endpoint for the worst-case accidental release scenario for the following process(es) is
less than the distance to the nearestpublic receptor: [list process(es)]. Within the past five years, the process(es) has (have) had no accidental release that caused offsite impacts provided in the risk management program rule (40 § 68.12

CFR 68.10(b)(1)). No additional measures are necessary to prevent offsite impacts from accidental releases. In the event of fire, explosion, or a releaseof a regulated substance from the process(es), entry within the distance tothe specified endpoints may pose a danger to public emergency responders.Therefore, public emergency responders should not enter this area except as arranged with the emergency contact indicated in the RMP. The undersignedcertifies that, to the best of my knowledge, information, and belief, formedafter reasonable inquiry, the information submitted is true, accurate, and complete. [Signature, title, date signed].’’

(c) Program 2 requirements. In addition to meeting the requirements of paragraph (a) of this section, the owner or operator of a stationary source witha process subject to Program 2, as provided in § 68.10(c), shall:

(1) Develop and implement a management system as provided in § 68.15;

(2) Conduct a hazard assessment as provided in §§ 68.20 through 68.42;

(3) Implement the Program 2 prevention steps provided in §§ 68.48 through
68.60or implement the Program 3 prevention steps provided in §§ 68.65 through 68.87;

(4) Develop and implement an emergency response program as provided in §§ 68.90 to 68.95; and

(5) Submit as part of the RMP the data on prevention program elements for Program 2 processes as provided in § 68.170.

(d) Program 3 requirements. In addition to meeting the requirements of paragraph (a) of this section, the owner or operator of a stationary source witha process subject to Program 3, as provided in § 68.10(d) shall:

(1) Develop and implement a management system as provided in § 68.15;

(2) Conduct a hazard assessment as provided in §§ 68.20 through 68.42;

(3) Implement the prevention requirements of §§ 68.65 through 68.87;

(4) Develop and implement an emergency response program as provided in §§ 68.90 to 68.95 of this part; and

(5) Submit as part of the RMP the data on prevention program elements

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for Program 3 processes as provided in § 68.175.

[61 FR 31718, June 20, 1996]

§ 68.15 Management.

(a) The owner or operator of a stationary source with processes subjectto Program 2 or Program 3 shall develop a management system to overseethe implementation of the risk management program elements.

(b) The owner or operator shall assign a qualified person or position that has the overall responsibility for thedevelopment, implementation, and integration of the risk management program elements.

(c) When responsibility for implementing individual requirements of this part is assigned to persons otherthan the person identified under paragraph (b) of this section, the names orpositions of these people shall be documented and the lines of authority defined through an organization chart or similar document.

[61 FR 31718, June 20, 1996]

Subpart B—Hazard Assessment

S OURCE : 61 FR 31718, June 20, 1996, unless
otherwise noted.

§ 68.20 Applicability.

The owner or operator of a stationary source subject to this part shall prepare a worst-case release scenario analysis as provided in § 68.25 of thispart and complete the five-year accident history as provided in § 68.42. The owner or operator of a Program 2 and 3 process must comply with all sections in this subpart for these processes.

§ 68.22 Offsite consequence analysis parameters. (a) Endpoints. For analyses of offsite consequences, the following endpoints shall be used:

(1) Toxics. The toxic endpoints provided in appendix A of this part.

(2) Flammables. The endpoints forflammables vary according to the scenarios studied:

(i) Explosion. An overpressure of 1 psi.

(ii) Radiant heat/exposure time. A radiant heat of 5 kw/m 2 for 40 seconds. 40 CFR Ch. I (7–1–98 Edition)

(iii) Lower flammability limit. A lower flammability limit as provided in NFPA documents or other generally recognized sources.

(b) Wind speed/atmospheric stabilityclass. For the worst-case release analysis, the owner or operator shall use a wind speed of 1.5 meters per second and F atmospheric stability class. If the owner or operator can demonstratethat local meteorological data applicable to the stationary source show ahigher minimum wind speed or less stable atmosphere at all times during the previous three years, these minimumsmay be used. For analysis of alternative scenarios, the owner or operator may use the typical meteorological conditions for the stationary source.

(c) Ambient temperature/humidity. For worst-case release analysis of a regulated toxic substance, the owner or operator shall use the highest daily maximum temperature in the previous three years and average humidity forthe site, based on temperature/humidity data gathered at the stationarysource or at a local meteorological station; an owner or operator using the
RMP Offsite Consequence Analysis Guidance may use 25 ° C and 50 percent humidity as values for these variables. For analysis of alternative scenarios, the owner or operator may use typical temperature/humidity data gathered atthe stationary source or at a local meteorological station.

(d) Height of release. The worst-case release of a regulated toxic substance shall be analyzed assuming a ground level (0 feet) release. For an alternative scenario analysis of a regulated toxicsubstance, release height may be determined by the release scenario.

(e) Surface roughness. The owner or operator shall use either urban or rural topography, as appropriate. Urban means that there are many obstacles in the immediate area; obstacles include buildings or trees. Rural means there are no buildings in the immediate area and the terrain is generally flat and unobstructed.

(f) Dense or neutrally buoyant gases. The owner or operator shall ensurethat tables or models used for dispersion analysis of regulated toxic substances appropriately account for gas density.

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(g) Temperature of released substance. For worst case, liquids other than gases liquified by refrigeration only shall be considered to be releasedat the highest daily maximum temperature, based on data for the previous three years appropriate for thestationary source, or at process temperature, whichever is higher. For alternative scenarios, substances may be considered to be released at a processor ambient temperature that is appropriate for the scenario.

§ 68.25 Worst-case release scenario analysis.

(a) The owner or operator shall analyze and report in the RMP:

(1) For Program 1 processes, one worst-case release scenario for each Program 1 process;

(2) For Program 2 and 3 processes: (i) One worst-case release scenario that is estimated to create the greatestdistance in any direction to an endpoint provided in appendix A of thispart resulting from an accidental release of regulated toxic substancesfrom covered processes under worstcase conditions defined in § 68.22;

(ii) One worst-case release scenario that is estimated to create the greatestdistance in any direction to an endpoint defined in § 68.22(a) resulting froman accidental release of regulated flammable substances from covered processes under worst-case conditions defined in § 68.22; and

(iii) Additional worst-case releasescenarios for a hazard class if a worstcase release from another covered process at the stationary source potentially affects public receptors different fromthose potentially affected by the worstcase release scenario developed under paragraphs (a)(2)(i) or (a)(2)(ii) of this

section.

(b) Determination of worst-case release quantity. The worst-case release quantity shall be the greater of the following:

(1) For substances in a vessel, the greatest amount held in a single vessel, taking into account administrativecontrols that limit the maximum quantity; or

(2) For substances in pipes, the greatest amount in a pipe, taking into ac­ § 68.25

count administrative controls that limit the maximum quantity.

(c) Worst-case release scenario—toxic

gases. (1) For regulated toxic substances that are normally gases at ambient temperature and handled as a gas or as a liquid under pressure, the owner

or operator shall assume that thequantity in the vessel or pipe, as determined under paragraph (b) of this section, is released as a gas over 10 minutes. The release rate shall be assumed to be the total quantity divided by 10 unless passive mitigation systems are in place.

(2) For gases handled as refrigerated liquids at ambient pressure:

(i) If the released substance is notcontained by passive mitigation systems or if the contained pool would have a depth of 1 cm or less, the owneror operator shall assume that the substance is released as a gas in 10 minutes;

(ii) If the released substance is contained by passive mitigation systems in a pool with a depth greater than 1 cm, the owner or operator may assume that the quantity in the vessel or pipe, as determined under paragraph (b) of this section, is spilled instantaneouslyto form a liquid pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance and at the conditions specified in paragraph (d) of this section.

(d) Worst-case release scenario—toxic liquids. (1) For regulated toxic substances that are normally liquids atambient temperature, the owner or operator shall assume that the quantity in the vessel or pipe, as determined under paragraph (b) of this section, is spilled instantaneously to form a liquid pool.

(i) The surface area of the pool shall be determined by assuming that theliquid spreads to 1 centimeter deep unless passive mitigation systems are in place that serve to contain the spilland limit the surface area. Where passive mitigation is in place, the surface area of the contained liquid shall be used to calculate the volatilization

rate.

(ii) If the release would occur onto a surface that is not paved or smooth, the owner or operator may take into

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account the actual surface characteristics.

(2) The volatilization rate shall account for the highest daily maximum temperature occurring in the past three years, the temperature of thesubstance in the vessel, and the concentration of the substance if the liquid spilled is a mixture or solution.

(3) The rate of release to air shall be determined from the volatilization rateof the liquid pool. The owner or operator may use the methodology in the
RMP Offsite Consequence AnalysisGuidance or any other publicly available techniques that account for the modeling conditions and are recognized by industry as applicable as part of current practices. Proprietary modelsthat account for the modeling conditions may be used provided the owner or operator allows the implementingagency access to the model and describes model features and differences from publicly available models to local emergency planners upon request.

(e) Worst-case release scenario— flammables. The owner or operator shallassume that the quantity of the substance, as determined under paragraph (b) of this section, vaporizes resultingin a vapor cloud explosion. A yield factor of 10 percent of the available energy released in the explosion shall be used to determine the distance to the explosion endpoint if the model used is based on TNT-equivalent methods.

(f) Parameters to be applied. The owner or operator shall use the parameters defined in § 68.22 to determine distanceto the endpoints. The owner or operator may use the methodology providedin the RMP Offsite Consequence Analysis Guidance or any commercially orpublicly available air dispersion modeling techniques, provided the techniques account for the modeling conditionsand are recognized by industry as applicable as part of current practices. Proprietary models that account for the modeling conditions may be used provided the owner or operator allows the implementing agency access to the model and describes model features and differences from publicly available models to local emergency planners upon request.

(g) Consideration of passive mitigation

. Passive mitigation systems may be 40 CFR Ch. I (7–1–98 Edition)

considered for the analysis of worstcase provided that the mitigation system is capable of withstanding the release event triggering the scenario and
would still function as intended.

(h) Factors in selecting a worst-case scenario. Notwithstanding the provisions of paragraph (b) of this section, the owner or operator shall select as the worst case for flammable regulatedsubstances or the worst case for regulated toxic substances, a scenario basedon the following factors if such a scenario would result in a greater distance to an endpoint defined in § 68.22(a) beyond the stationary source boundarythan the scenario provided under paragraph (b) of this section:

(1) Smaller quantities handled athigher process temperature or pressure; and

(2) Proximity to the boundary of the stationary source.

§ 68.28 Alternative release scenario analysis.

(a) The number of scenarios. The owner or operator shall identify and analyze at least one alternative releasescenario for each regulated toxic substance held in a covered process(es) and
at least one alternative release scenario to represent all flammable substances held in covered processes.

(b) Scenarios to consider. (1) For each scenario required under paragraph (a) of this section, the owner or operator
shall select a scenario:

(i) That is more likely to occur than
the worst-case release scenario under § 68.25; and

(ii) That will reach an endpoint offsite, unless no such scenario exists.

(2) Release scenarios considered should include, but are not limited to, the following, where applicable:

(i) Transfer hose releases due to splits or sudden hose uncoupling;

(ii) Process piping releases from failures at flanges, joints, welds, valves and valve seals, and drains or bleeds;

(iii) Process vessel or pump releases due to cracks, seal failure, or drain, bleed, or plug failure;

(iv) Vessel overfilling and spill, or overpressurization and venting through relief valves or rupture disks; and

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(v) Shipping container mishandling and breakage or puncturing leading to a spill.

(c) Parameters to be applied. Theowner or operator shall use the appropriate parameters defined in § 68.22 to determine distance to the endpoints. The owner or operator may use either the methodology provided in the RMP Offsite Consequence Analysis Guidanceor any commercially or publicly available air dispersion modeling techniques, provided the techniques account for the specified modeling conditions and are recognized by industry as applicable as part of current practices. Proprietary models that account for the modeling conditions may be used provided the owner or operator allows the implementing agency access to the model and describes model features and differences from publicly available models to local emergency planners upon request.

(d) Consideration of mitigation. Active and passive mitigation systems may be considered provided they are capable of withstanding the event that triggered the release and would still be functional.

(e) Factors in selecting scenarios. The owner or operator shall consider the following in selecting alternative release scenarios:

(1) The five-year accident history provided in § 68.42; and

(2) Failure scenarios identified under § 68.50 or § 68.67.

§ 68.30 Defining offsite impacts—population.
(a) The owner or operator shall estimate in the RMP the population within a circle with its center at the point of the release and a radius determined by the distance to the endpoint defined in § 68.22(a).

(b) Population to be defined. Population shall include residential population. The presence of institutions (schools, hospitals, prisons), parks andrecreational areas, and major commercial, office, and industrial buildings shall be noted in the RMP.

(c) Data sources acceptable. The owner or operator may use the most recentCensus data, or other updated information, to estimate the population potentially affected. § 68.39

(d) Level of accuracy. Population shall be estimated to two significant digits.

§ 68.33 Defining offsite impacts—environment.
(a) The owner or operator shall list in the RMP environmental receptors within a circle with its center at thepoint of the release and a radius determined by the distance to the endpoint defined in § 68.22(a) of this part.

(b) Data sources acceptable. Theowner or operator may rely on information provided on local U.S. Geological Survey maps or on any data source containing U.S.G.S. data to identify environmental receptors.

68.36 Review and update.

(a) The owner or operator shall review and update the offsite consequence analyses at least once every five years.

(b) If changes in processes, quantities stored or handled, or any other aspectof the stationary source might reasonably be expected to increase or decrease the distance to the endpoint by a factor of two or more, the owner oroperator shall complete a revised analysis within six months of the change and submit a revised risk management plan as provided in § 68.190.

§ 68.39 Documentation.

The owner or operator shall maintain the following records on the offsite consequence analyses:

(a) For worst-case scenarios, a description of the vessel or pipeline andsubstance selected as worst case, assumptions and parameters used, andthe rationale for selection; assumptions shall include use of any administrative controls and any passive mitigation that were assumed to limit thequantity that could be released. Documentation shall include the anticipated effect of the controls and mitigation on the release quantity and rate.

(b) For alternative release scenarios,a description of the scenarios identified, assumptions and parameters used, and the rationale for the selection of specific scenarios; assumptions shallinclude use of any administrative controls and any mitigation that were assumed to limit the quantity that could

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be released. Documentation shall include the effect of the controls and mitigation on the release quantity and

rate.

(c) Documentation of estimatedquantity released, release rate, and duration of release.

(d) Methodology used to determine distance to endpoints.

(e) Data used to estimate population
and environmental receptors potentially affected.

§ 68.42 Five-year accident history.

(a) The owner or operator shall include in the five-year accident history all accidental releases from coveredprocesses that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries,evacuations, sheltering in place, property damage, or environmental damage.

(b) Data required. For each accidental release included, the owner or operator shall report the following information:

(1) Date, time, and approximate duration of the release;

(2) Chemical(s) released; (3) Estimated quantity released in pounds;

(4) The type of release event and its

source;

(5) Weather conditions, if known; (6) On-site impacts; (7) Known offsite impacts; (8) Initiating event and contributing factors if known;

(9) Whether offsite responders were notified if known; and

(10) Operational or process changes that resulted from investigation of the release.

(c) Level of accuracy. Numerical estimates may be provided to two significant digits.

Subpart C—Program 2 Prevention Program

S OURCE : 61 FR 31721, June 20, 1996, unless
otherwise noted.

§ 68.48 Safety information.

(a) The owner or operator shall compile and maintain the following up-todate safety information related to the 40 CFR Ch. I (7–1–98 Edition)

regulated substances, processes, and equipment:

(1) Material Safety Data Sheets that

meet the requirements of 29 CFR 1910.1200(g);

(2) Maximum intended inventory ofequipment in which the regulated substances are stored or processed;

(3) Safe upper and lower temperatures, pressures, flows, and compositions;

(4) Equipment specifications; and (5) Codes and standards used to design, build, and operate the process.

(b) The owner or operator shall ensure that the process is designed incompliance with recognized and generally accepted good engineering practices. Compliance with Federal or stateregulations that address industry-specific safe design or with industry-specific design codes and standards may be used to demonstrate compliance with this paragraph.

(c) The owner or operator shall update the safety information if a majorchange occurs that makes the information inaccurate.

§ 68.50 Hazard review.

(a) The owner or operator shall conduct a review of the hazards associated with the regulated substances, process,and procedures. The review shall identify the following:

(1) The hazards associated with the process and regulated substances;

(2) Opportunities for equipment malfunctions or human errors that could cause an accidental release;

(3) The safeguards used or needed tocontrol the hazards or prevent equipment malfunction or human error; and

(4) Any steps used or needed to detect
or monitor releases.

(b) The owner or operator may usechecklists developed by persons or organizations knowledgeable about the process and equipment as a guide to conducting the review. For processes designed to meet industry standards orFederal or state design rules, the hazard review shall, by inspecting all equipment, determine whether theprocess is designed, fabricated, and operated in accordance with the applicable standards or rules.

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(c) The owner or operator shall document the results of the review and ensure that problems identified are resolved in a timely manner.

(d) The review shall be updated at least once every five years. The owner or operator shall also conduct reviewswhenever a major change in the process occurs; all issues identified in the review shall be resolved before startup of the changed process.

§ 68.52 Operating procedures.

(a) The owner or operator shall prepare written operating procedures that provide clear instructions or steps for safely conducting activities associated with each covered process consistent with the safety information for thatprocess. Operating procedures or instructions provided by equipment manufacturers or developed by persons or organizations knowledgeable about the process and equipment may be used asa basis for a stationary source’s operating procedures.

(b) The procedures shall address the following:

(1) Initial startup; (2) Normal operations; (3) Temporary operations; (4) Emergency shutdown and operations;

(5) Normal shutdown; (6) Startup following a normal or emergency shutdown or a major change that requires a hazard review;

(7) Consequences of deviations andsteps required to correct or avoid deviations; and

(8) Equipment inspections. (c) The owner or operator shall ensure that the operating procedures are updated, if necessary, whenever amajor change occurs and prior to startup of the changed process.

§ 68.54 Training.

(a) The owner or operator shall ensure that each employee presently operating a process, and each employee newly assigned to a covered process have been trained or tested competent in the operating procedures provided in § 68.52 that pertain to their duties. For those employees already operating a process on June 21, 1999, the owner or operator may certify in writing that the employee has the required knowl­ § 68.56

edge, skills, and abilities to safelycarry out the duties and responsibilities as provided in the operating procedures.

(b) Refresher training. Refresher training shall be provided at least every three years, and more often if necessary, to each employee operating a process to ensure that the employee
understands and adheres to the current operating procedures of the process. The owner or operator, in consultationwith the employees operating the process, shall determine the appropriate frequency of refresher training.

(c) The owner or operator may use training conducted under Federal orstate regulations or under industryspecific standards or codes or trainingconducted by covered process equipment vendors to demonstrate compliance with this section to the extentthat the training meets the requirements of this section.

(d) The owner or operator shall ensure that operators are trained in any updated or new procedures prior to startup of a process after a major change.

§ 68.56 Maintenance.

(a) The owner or operator shall prepare and implement procedures tomaintain the on-going mechanical integrity of the process equipment. The owner or operator may use procedures or instructions provided by coveredprocess equipment vendors or procedures in Federal or state regulations orindustry codes as the basis for stationary source maintenance procedures.

(b) The owner or operator shall train or cause to be trained each employee involved in maintaining the on-going mechanical integrity of the process. To ensure that the employee can perform the job tasks in a safe manner, each such employee shall be trained in the hazards of the process, in how to avoid or correct unsafe conditions, and in theprocedures applicable to the employee’s job tasks.

(c) Any maintenance contractor shall
ensure that each contract maintenance employee is trained to perform the

maintenance procedures developed under paragraph (a) of this section.

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(d) The owner or operator shall perform or cause to be performed inspections and tests on process equipment. Inspection and testing procedures shallfollow recognized and generally accepted good engineering practices. The frequency of inspections and tests of process equipment shall be consistent with applicable manufacturers’ recommendations, industry standards or codes, good engineering practices, and prior operating experience.

§ 68.58 Compliance audits.

(a) The owner or operator shall certify that they have evaluated compliance with the provisions of this subpart at least every three years to verify that the procedures and practices developed under the rule are adequate and are being followed.

(b) The compliance audit shall be conducted by at least one person knowledgeable in the process.

(c) The owner or operator shall develop a report of the audit findings.

(d) The owner or operator shall promptly determine and document an appropriate response to each of the findings of the compliance audit and document that deficiencies have been corrected.

(e) The owner or operator shall retain the two (2) most recent compliance audit reports. This requirement doesnot apply to any compliance audit report that is more than five years old.

§ 68.60 Incident investigation.

(a) The owner or operator shall investigate each incident which resulted in, or could reasonably have resulted in a catastrophic release.

(b) An incident investigation shall be initiated as promptly as possible, but not later than 48 hours following the
incident.

(c) A summary shall be prepared at the conclusion of the investigation which includes at a minimum:

(1) Date of incident; (2) Date investigation began; (3) A description of the incident; (4) The factors that contributed to the incident; and,

(5) Any recommendations resulting from the investigation.

(d) The owner or operator shallpromptly address and resolve the inves40 CFR Ch. I (7–1–98 Edition)

tigation findings and recommendations. Resolutions and corrective actions shall be documented.

(e) The findings shall be reviewed with all affected personnel whose job tasks are affected by the findings.

(f) Investigation summaries shall be retained for five years.

Subpart D—Program 3 Prevention Program

S OURCE : 61 FR 31722, June 20, 1996, unless
otherwise noted.

§ 68.65 Process safety information.

(a) In accordance with the schedule set forth in § 68.67, the owner or operator shall complete a compilation ofwritten process safety information before conducting any process hazardanalysis required by the rule. The compilation of written process safety information is to enable the owner or operator and the employees involved in operating the process to identify and understand the hazards posed by those processes involving regulated substances. This process safety information shall include information pertaining to the hazards of the regulated substancesused or produced by the process, information pertaining to the technology ofthe process, and information pertaining to the equipment in the process.

(b) Information pertaining to the hazards of the regulated substances in the process. This information shall consist of at least the following:

(1) Toxicity information; (2) Permissible exposure limits; (3) Physical data; (4) Reactivity data: (5) Corrosivity data; (6) Thermal and chemical stability data; and

(7) Hazardous effects of inadvertent mixing of different materials that could foreseeably occur.

N OTE TO PARAGRAPH (b): Material Safety Data Sheets meeting the requirements of 29 CFR 1910.1200(g) may be used to comply with this requirement to the extent they containthe information required by this subparagraph.

(c) Information pertaining to the technology of the process.

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(1) Information concerning the technology of the process shall include at least the following:

(i) A block flow diagram or simplified process flow diagram;

(ii) Process chemistry; (iii) Maximum intended inventory; (iv) Safe upper and lower limits for such items as temperatures, pressures, flows or compositions; and,

(v) An evaluation of the consequences of deviations.

(2) Where the original technical information no longer exists, such information may be developed in conjunction with the process hazard analysisin sufficient detail to support the analysis.

(d) Information pertaining to the equipment in the process.

(1) Information pertaining to the equipment in the process shall include:

(i) Materials of construction; (ii) Piping and instrument diagrams (P&ID’s);

(iii) Electrical classification; (iv) Relief system design and design basis;

(v) Ventilation system design; (vi) Design codes and standards employed;

(vii) Material and energy balances for processes built after June 21, 1999; and

(viii) Safety systems (e.g. interlocks, detection or suppression systems).

(2) The owner or operator shall document that equipment complies with recognized and generally accepted good engineering practices.

(3) For existing equipment designed and constructed in accordance with codes, standards, or practices that are no longer in general use, the owner or operator shall determine and documentthat the equipment is designed, maintained, inspected, tested, and operating in a safe manner.

§ 68.67 Process hazard analysis.

(a) The owner or operator shall perform an initial process hazard analysis(hazard evaluation) on processes covered by this part. The process hazard analysis shall be appropriate to the complexity of the process and shallidentify, evaluate, and control the hazards involved in the process. The owneror operator shall determine and document the priority order for conducting § 68.67

process hazard analyses based on a rationale which includes such considerations as extent of the process hazards,number of potentially affected employees, age of the process, and operatinghistory of the process. The process hazard analysis shall be conducted as soon as possible, but not later than June 21,1999. Process hazards analyses completed to comply with 29 CFR 1910.119(e) are acceptable as initial process hazards analyses. These process hazard analyses shall be updated and revalidated, based on their completion
date.

(b) The owner or operator shall useone or more of the following methodologies that are appropriate to determine and evaluate the hazards of the process being analyzed.

(1) What-If; (2) Checklist; (3) What-If/Checklist; (4) Hazard and Operability Study (HAZOP);

(5) Failure Mode and Effects Analysis (FMEA);

(6) Fault Tree Analysis; or (7) An appropriate equivalent methodology.

(c) The process hazard analysis shall
address:

(1) The hazards of the process; (2) The identification of any previous incident which had a likely potential for catastrophic consequences.

(3) Engineering and administrative controls applicable to the hazards andtheir interrelationships such as appropriate application of detection methodologies to provide early warning ofreleases. (Acceptable detection methods might include process monitoring
and control instrumentation with alarms, and detection hardware such as hydrocarbon sensors.);

(4) Consequences of failure of engineering and administrative controls;

(5) Stationary source siting; (6) Human factors; and (7) A qualitative evaluation of a range of the possible safety and health effects of failure of controls.

(d) The process hazard analysis shall be performed by a team with expertise in engineering and process operations, and the team shall include at least one employee who has experience and knowledge specific to the process being

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evaluated. Also, one member of the team must be knowledgeable in thespecific process hazard analysis methodology being used.

(e) The owner or operator shall establish a system to promptly address the team’s findings and recommendations; assure that the recommendations are resolved in a timely manner and thatthe resolution is documented; document what actions are to be taken; complete actions as soon as possible; develop a written schedule of whenthese actions are to be completed; communicate the actions to operating,
maintenance and other employees whose work assignments are in the process and who may be affected by the recommendations or actions.

(f) At least every five (5) years after the completion of the initial process hazard analysis, the process hazardanalysis shall be updated and revalidated by a team meeting the requirements in paragraph (d) of this section,to assure that the process hazard analysis is consistent with the currentprocess. Updated and revalidated process hazard analyses completed to comply with 29 CFR 1910.119(e) are acceptable to meet the requirements of this paragraph.

(g) The owner or operator shall retain process hazards analyses and updates or revalidations for each process covered by this section, as well as thedocumented resolution of recommendations described in paragraph (e) of this section for the life of the process.

§ 68.69 Operating procedures.

(a) The owner or operator shall develop and implement written operatingprocedures that provide clear instructions for safely conducting activitiesinvolved in each covered process consistent with the process safety information and shall address at least the following elements.

(1) Steps for each operating phase: (i) Initial startup; (ii) Normal operations; (iii) Temporary operations; (iv) Emergency shutdown including the conditions under which emergencyshutdown is required, and the assignment of shutdown responsibility to qualified operators to ensure that 40 CFR Ch. I (7–1–98 Edition)

emergency shutdown is executed in a safe and timely manner.

(v) Emergency operations; (vi) Normal shutdown; and, (vii) Startup following a turnaround, or after an emergency shutdown.

(2) Operating limits: (i) Consequences of deviation; and (ii) Steps required to correct or avoid deviation.

(3) Safety and health considerations: (i) Properties of, and hazards presented by, the chemicals used in the

process;

(ii) Precautions necessary to preventexposure, including engineering controls, administrative controls, and personal protective equipment;

(iii) Control measures to be taken if physical contact or airborne exposure

occurs;

(iv) Quality control for raw materialsand control of hazardous chemical inventory levels; and,

(v) Any special or unique hazards. (4) Safety systems and their functions.

(b) Operating procedures shall be readily accessible to employees who work in or maintain a process.

(c) The operating procedures shall bereviewed as often as necessary to assure that they reflect current operating practice, including changes that result from changes in process chemicals, technology, and equipment, and changes to stationary sources. Theowner or operator shall certify annually that these operating procedures
are current and accurate.

(d) The owner or operator shall develop and implement safe work practices to provide for the control of hazards during operations such as lockout/ tagout; confined space entry; openingprocess equipment or piping; and control over entrance into a stationary

source by maintenance, contractor, laboratory, or other support personnel. These safe work practices shall applyto employees and contractor employees.

§ 68.71 Training.

(a) Initial training. (1) Each employeepresently involved in operating a process, and each employee before being involved in operating a newly assigned process, shall be trained in an overview

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of the process and in the operating procedures as specified in § 68.69. The training shall include emphasis on the specific safety and health hazards,emergency operations including shutdown, and safe work practices applicable to the employee’s job tasks.

(2) In lieu of initial training for thoseemployees already involved in operating a process on June 21, 1999 an owner or operator may certify in writing thatthe employee has the required knowledge, skills, and abilities to safelycarry out the duties and responsibilities as specified in the operating procedures.

(b) Refresher training. Refresher training shall be provided at least everythree years, and more often if necessary, to each employee involved in operating a process to assure that the employee understands and adheres to the current operating procedures of theprocess. The owner or operator, in consultation with the employees involvedin operating the process, shall determine the appropriate frequency of refresher training.

(c) Training documentation. The owner or operator shall ascertain that eachemployee involved in operating a process has received and understood the training required by this paragraph. The owner or operator shall prepare a record which contains the identity of the employee, the date of training, andthe means used to verify that the employee understood the training.

§ 68.73 Mechanical integrity.

(a) Application. Paragraphs (b) through (f) of this section apply to the following process equipment:

(1) Pressure vessels and storage tanks;

(2) Piping systems (including piping components such as valves);

(3) Relief and vent systems and devices;

(4) Emergency shutdown systems; (5) Controls (including monitoringdevices and sensors, alarms, and interlocks) and,

(6) Pumps. (b) Written procedures. The owner or operator shall establish and implementwritten procedures to maintain the ongoing integrity of process equipment. § 68.73

(c) Training for process maintenance

activities. The owner or operator shalltrain each employee involved in maintaining the on-going integrity of process equipment in an overview of thatprocess and its hazards and in the procedures applicable to the employee’s job tasks to assure that the employee can perform the job tasks in a safe

manner.

(d) Inspection and testing. (1) Inspections and tests shall be performed on process equipment.

(2) Inspection and testing procedures shall follow recognized and generally accepted good engineering practices.

(3) The frequency of inspections andtests of process equipment shall be consistent with applicable manufacturers’ recommendations and good engineeringpractices, and more frequently if determined to be necessary by prior operating experience.

(4) The owner or operator shall document each inspection and test that has been performed on process equipment. The documentation shall identify the date of the inspection or test, the nameof the person who performed the inspection or test, the serial number or other identifier of the equipment onwhich the inspection or test was performed, a description of the inspection or test performed, and the results of the inspection or test.

(e) Equipment deficiencies. The owner or operator shall correct deficiencies in equipment that are outside acceptablelimits (defined by the process safety information in § 68.65) before further use or in a safe and timely manner when necessary means are taken to assure safe operation.

(f) Quality assurance. (1) In the construction of new plants and equipment, the owner or operator shall assure thatequipment as it is fabricated is suitable for the process application for which they will be used.

(2) Appropriate checks and inspections shall be performed to assure that equipment is installed properly and consistent with design specifications and the manufacturer’s instructions.

(3) The owner or operator shall assure that maintenance materials, spare parts and equipment are suitable for the process application for which they will be used.

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§ 68.75 Management of change.

(a) The owner or operator shall establish and implement written proceduresto manage changes (except for ‘‘replacements in kind’’) to process chemicals, technology, equipment, and procedures; and, changes to stationary sources that affect a covered process.

(b) The procedures shall assure thatthe following considerations are addressed prior to any change:

(1) The technical basis for the proposed change;

(2) Impact of change on safety and health;

(3) Modifications to operating procedures;

(4) Necessary time period for the change; and,

(5) Authorization requirements for the proposed change.

(c) Employees involved in operating a process and maintenance and contractemployees whose job tasks will be affected by a change in the process shall be informed of, and trained in, the change prior to start-up of the process or affected part of the process.

(d) If a change covered by this paragraph results in a change in the process safety information required by § 68.65 ofthis part, such information shall be updated accordingly.

(e) If a change covered by this paragraph results in a change in the operating procedures or practices required by § 68.69, such procedures or practices shall be updated accordingly.

§ 68.77 Pre-startup review.

(a) The owner or operator shall perform a pre-startup safety review fornew stationary sources and for modified stationary sources when the modification is significant enough to require a change in the process safety information.

(b) The pre-startup safety reviewshall confirm that prior to the introduction of regulated substances to a

process:

(1) Construction and equipment is in accordance with design specifications;

(2) Safety, operating, maintenance, and emergency procedures are in place and are adequate;

(3) For new stationary sources, aprocess hazard analysis has been performed and recommendations have 40 CFR Ch. I (7–1–98 Edition)

been resolved or implemented before startup; and modified stationarysources meet the requirements contained in management of change, § 68.75.

(4) Training of each employee involved in operating a process has been completed.

§ 68.79 Compliance audits.

(a) The owner or operator shall certify that they have evaluated compliance with the provisions of this section at least every three years to verifythat the procedures and practices developed under the standard are adequate and are being followed.

(b) The compliance audit shall be conducted by at least one person knowledgeable in the process.

(c) A report of the findings of the audit shall be developed.

(d) The owner or operator shall promptly determine and document an appropriate response to each of the findings of the compliance audit, and document that deficiencies have been corrected.

(e) The owner or operator shall retain the two (2) most recent compliance audit reports.

§ 68.81 Incident investigation.

(a) The owner or operator shall investigate each incident which resulted in, or could reasonably have resulted in acatastrophic release of a regulated substance.

(b) An incident investigation shall be initiated as promptly as possible, but not later than 48 hours following the
incident.

(c) An incident investigation team shall be established and consist of at least one person knowledgeable in the process involved, including a contract employee if the incident involved work of the contractor, and other personswith appropriate knowledge and experience to thoroughly investigate and analyze the incident.

(d) A report shall be prepared at the conclusion of the investigation which includes at a minimum:

(1) Date of incident; (2) Date investigation began; (3) A description of the incident; (4) The factors that contributed to the incident; and,

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(5) Any recommendations resulting from the investigation.

(e) The owner or operator shall establish a system to promptly address and resolve the incident report findings andrecommendations. Resolutions and corrective actions shall be documented.

(f) The report shall be reviewed with all affected personnel whose job tasksare relevant to the incident findings including contract employees where applicable.

(g) Incident investigation reports shall be retained for five years.

§ 68.83 Employee participation.

(a) The owner or operator shall develop a written plan of action regarding the implementation of the employee participation required by this

section.

(b) The owner or operator shall consult with employees and their representatives on the conduct and development of process hazards analyses andon the development of the other elements of process safety management in this rule.

(c) The owner or operator shall provide to employees and their representatives access to process hazard analyses and to all other information required to be developed under this rule.

§ 68.85 Hot work permit.

(a) The owner or operator shall issuea hot work permit for hot work operations conducted on or near a covered

process.

(b) The permit shall document thatthe fire prevention and protection requirements in 29 CFR 1910.252(a) have been implemented prior to beginningthe hot work operations; it shall indicate the date(s) authorized for hot work; and identify the object on whichhot work is to be performed. The permit shall be kept on file until completion of the hot work operations.

§ 68.87 Contractors.

(a) Application. This section applies to contractors performing maintenanceor repair, turnaround, major renovation, or specialty work on or adjacent to a covered process. It does not apply

to contractors providing incidental services which do not influence process safety, such as janitorial work, food § 68.87

and drink services, laundry, delivery or other supply services.

(b) Owner or operator responsibilities. (1) The owner or operator, when selecting a contractor, shall obtain and evaluate information regarding the contract owner or operator’s safety performance and programs.

(2) The owner or operator shall inform contract owner or operator of the known potential fire, explosion, or toxic release hazards related to the contractor’s work and the process.

(3) The owner or operator shall explain to the contract owner or operator the applicable provisions of subpart E of this part.

(4) The owner or operator shall develop and implement safe work practices consistent with § 68.69(d), to control the entrance, presence, and exit of the contract owner or operator and contract employees in covered process

areas.

(5) The owner or operator shall periodically evaluate the performance ofthe contract owner or operator in fulfilling their obligations as specified in paragraph (c) of this section.

(c) Contract owner or operator responsibilities. (1) The contract owner or operator shall assure that each contractemployee is trained in the work practices necessary to safely perform his/ her job.

(2) The contract owner or operatorshall assure that each contract employee is instructed in the known potential fire, explosion, or toxic release hazards related to his/her job and the process, and the applicable provisions of the emergency action plan.

(3) The contract owner or operatorshall document that each contract employee has received and understood the training required by this section. Thecontract owner or operator shall prepare a record which contains the identity of the contract employee, the dateof training, and the means used to verify that the employee understood the training.

(4) The contract owner or operatorshall assure that each contract employee follows the safety rules of the stationary source including the safe work practices required by § 68.69(d).

(5) The contract owner or operator shall advise the owner or operator of

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any unique hazards presented by the contract owner or operator’s work, or of any hazards found by the contract owner or operator’s work.

Subpart E—Emergency Response

S OURCE : 61 FR 31725, June 20, 1996, unless
otherwise noted.

§ 68.90 Applicability.

(a) Except as provided in paragraph (b) of this section, the owner or operator of a stationary source with Program 2 and Program 3 processes shall comply with the requirements of § 68.95.

(b) The owner or operator of stationary source whose employees will notrespond to accidental releases of regulated substances need not comply with § 68.95 of this part provided that they meet the following:

(1) For stationary sources with any regulated toxic substance held in a process above the threshold quantity, the stationary source is included in the community emergency response plan developed under 42 U.S.C. 11003;

(2) For stationary sources with only regulated flammable substances held in a process above the threshold quantity, the owner or operator has coordinatedresponse actions with the local fire department; and

(3) Appropriate mechanisms are in place to notify emergency responders when there is a need for a response.

§ 68.95 Emergency response program.

(a) The owner or operator shall develop and implement an emergency response program for the purpose of protecting public health and the environment. Such program shall include the following elements:

(1) An emergency response plan,
which shall be maintained at the stationary source and contain at least the following elements:

(i) Procedures for informing the public and local emergency response agencies about accidental releases;

(ii) Documentation of proper first-aidand emergency medical treatment necessary to treat accidental human exposures; and 40 CFR Ch. I (7–1–98 Edition)

(iii) Procedures and measures for emergency response after an accidental release of a regulated substance;

(2) Procedures for the use of emergency response equipment and for its inspection, testing, and maintenance;

(3) Training for all employees in relevant procedures; and

(4) Procedures to review and update, as appropriate, the emergency responseplan to reflect changes at the stationary source and ensure that employees are informed of changes.

(b) A written plan that complies withother Federal contingency plan regulations or is consistent with the approach in the National Response Team’s Integrated Contingency Plan
Guidance (‘‘One Plan’’) and that,among other matters, includes the elements provided in paragraph (a) of this section, shall satisfy the requirements of this section if the owner or operator also complies with paragraph (c) of this

section.

(c) The emergency response plan developed under paragraph (a)(1) of this
section shall be coordinated with the community emergency response plan developed under 42 U.S.C. 11003. Uponrequest of the local emergency planning committee or emergency response officials, the owner or operator shallpromptly provide to the local emergency response officials informationnecessary for developing and implementing the community emergency response plan.

Subpart F—Regulated Substances for Accidental Release Prevention

S OURCE : 59 FR 4493, Jan. 31, 1994, unless otherwise noted. Redesignated at 61 FR 31717, June 20, 1996.

§ 68.100 Purpose.

This subpart designates substances to be listed under section 112(r)(3), (4),and (5) of the Clean Air Act, as amended, identifies their threshold quantities, and establishes the requirementsfor petitioning to add or delete substances from the list.

§ 68.115 Threshold determination.

(a) A threshold quantity of a regulated substance listed in § 68.130 is

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present at a stationary source if thetotal quantity of the regulated substance contained in a process exceeds the threshold.

(b) For the purposes of determiningwhether more than a threshold quantity of a regulated substance is present at the stationary source, the following exemptions apply:

(1) Concentrations of a regulated toxic
substance in a mixture. If a regulated substance is present in a mixture and the concentration of the substance is below one percent by weight of the mixture, the amount of the substance in the mixture need not be considered when determining whether more than a threshold quantity is present at the stationary source. Except for oleum, toluene 2,4-diisocyanate, toluene 2,6­ diisocyanate, and toluene diisocyanate(unspecified isomer), if the concentration of the regulated substance in the mixture is one percent or greater by weight, but the owner or operator can demonstrate that the partial pressureof the regulated substance in the mixture (solution) under handling or storage conditions in any portion of the process is less than 10 millimeters of mercury (mm Hg), the amount of thesubstance in the mixture in that portion of the process need not be considered when determining whether more than a threshold quantity is present atthe stationary source. The owner or operator shall document this partial pressure measurement or estimate.

(2) Concentrations of a regulated flammable substance in a mixture. (i) General provision. If a regulated substance ispresent in a mixture and the concentration of the substance is below one percent by weight of the mixture, the mixture need not be considered when determining whether more than a threshold quantity of the regulated substance is present at the stationarysource. Except as provided in paragraph (b)(2) (ii) and (iii) of this section,
if the concentration of the substance is one percent or greater by weight of themixture, then, for purposes of determining whether a threshold quantity is present at the stationary source, the entire weight of the mixture shall betreated as the regulated substance unless the owner or operator can demonstrate that the mixture itself does § 68.115

not have a National Fire ProtectionAssociation flammability hazard rating of 4. The demonstration shall be in
accordance with the definition of flammability hazard rating 4 in the NFPA704, Standard System for the Identification of the Hazards of Materials for Emergency Response, National Fire Protection Association, Quincy, MA,
1996. Available from the National Fire
Protection Association, 1 Batterymarch Park, Quincy, MA 02269– 9101. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5
U.S.C. 552(a) and 1 CFR part 51. Copies may be inspected at the Environmental Protection Agency Air Docket (6102), Attn: Docket No. A–96–O8, Waterside Mall, 401 M. St. SW., Washington DC; or at the Office of Federal Register at 800 North Capitol St., NW, Suite 700, Washington, DC. Boiling point andflash point shall be defined and determined in accordance with NFPA 30, Flammable and Combustible LiquidsCode, National Fire Protection Association, Quincy, MA, 1996. Available
from the National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02269–9101. This incorporationby reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be inspected at the Environmental Protection Agency Air Docket (6102), Attn: Docket No. A–96– O8, Waterside Mall, 401 M. St. SW.,Washington DC; or at the Office of Federal Register at 800 North Capitol St., NW., Suite 700, Washington, DC. The owner or operator shall document the
National Fire Protection Association flammability hazard rating.

(ii) Gasoline. Regulated substances ingasoline, when in distribution or related storage for use as fuel for internalcombustion engines, need not be considered when determining whether

more than a threshold quantity is present at a stationary source.

(iii) Naturally occurring hydrocarbon

mixtures. Prior to entry into a naturalgas processing plant or a petroleum refining process unit, regulated substances in naturally occurring hydrocarbon mixtures need not be considered when determining whether more than a

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threshold quantity is present at a stationary source. Naturally occurring hydrocarbon mixtures include anycombination of the following: condensate, crude oil, field gas, and produced water, each as defined in § 68.3 of this part.

(3) Articles. Regulated substances contained in articles need not be considered when determining whether more than a threshold quantity is present at the stationary source.

(4) Uses. Regulated substances, when in use for the following purposes, need not be included in determining whether

more than a threshold quantity is present at the stationary source:

(i) Use as a structural component of the stationary source;

(ii) Use of products for routine janitorial maintenance;

(iii) Use by employees of foods, drugs,cosmetics, or other personal items containing the regulated substance; and

(iv) Use of regulated substances present in process water or non-contactcooling water as drawn from the environment or municipal sources, or use of regulated substances present in air used either as compressed air or as part of combustion.

(5) Activities in laboratories. If a regulated substance is manufactured, processed, or used in a laboratory at a stationary source under the supervision ofa technically qualified individual as defined in § 720.3(ee) of this chapter, the quantity of the substance need not be considered in determining whether athreshold quantity is present. This exemption does not apply to:

(i) Specialty chemical production; (ii) Manufacture, processing, or useof substances in pilot plant scale operations; and

(iii) Activities conducted outside the laboratory.

[59 FR 4493, Jan. 31, 1994. Redesignated at 61 FR 31717, June 20, 1996, as amended at 63 FR 645, Jan. 6, 1998]

§ 68.120 Petition process.

(a) Any person may petition the Administrator to modify, by addition ordeletion, the list of regulated substances identified in § 68.130. Based onthe information presented by the petitioner, the Administrator may grant or deny a petition. 40 CFR Ch. I (7–1–98 Edition)

(b) A substance may be added to thelist if, in the case of an accidental release, it is known to cause or may be reasonably anticipated to cause death, injury, or serious adverse effects to
human health or the environment.

(c) A substance may be deleted from the list if adequate data on the health
and environmental effects of the substance are available to determine thatthe substance, in the case of an accidental release, is not known to cause and may not be reasonably anticipatedto cause death, injury, or serious adverse effects to human health or the

environment.

(d) No substance for which a national primary ambient air quality standard
has been established shall be added to the list. No substance regulated undertitle VI of the Clean Air Act, as amended, shall be added to the list.

(e) The burden of proof is on the petitioner to demonstrate that the criteriafor addition and deletion are met. A petition will be denied if this demonstration is not made.

(f) The Administrator will not acceptadditional petitions on the same substance following publication of a final notice of the decision to grant or deny a petition, unless new data becomesavailable that could significantly affect the basis for the decision.

(g) Petitions to modify the list of regulated substances must contain the following:

(1) Name and address of the petitioner and a brief description of the organization(s) that the petitioner represents, if applicable;

(2) Name, address, and telephonenumber of a contact person for the petition;

(3) Common chemical name(s), common synonym(s), Chemical Abstracts Service number, and chemical formula and structure;

(4) Action requested (add or delete a substance);

(5) Rationale supporting the petitioner’s position; that is, how the substance meets the criteria for addition and deletion. A short summary of the
rationale must be submitted along with a more detailed narrative; and

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(6) Supporting data; that is, the petition must include sufficient information to scientifically support the request to modify the list. Such information shall include:

(i) A list of all support documents; (ii) Documentation of literature searches conducted, including, but notlimited to, identification of the database(s) searched, the search strategy, dates covered, and printed results;

(iii) Effects data (animal, human, and
environmental test data) indicatingthe potential for death, injury, or serious adverse human and environmental impacts from acute exposure following an accidental release; printed copies of the data sources, in English, should be provided; and

(iv) Exposure data or previous accident history data, indicating the potential for serious adverse human
health or environmental effects from an accidental release. These data mayinclude, but are not limited to, physical and chemical properties of the substance, such as vapor pressure; modeling results, including data and assumptions used and model documentation; and historical accident data, citing
data sources.

(h) Within 18 months of receipt of apetition, the Administrator shall publish in the F EDERAL R EGISTER a notice either denying the petition or granting the petition and proposing a listing.

§ 68.125 Exemptions.

Agricultural nutrients. Ammonia used as an agricultural nutrient, when heldby farmers, is exempt from all provisions of this part.

§ 68.130 List of substances.

(a) Regulated toxic and flammable substances under section 112(r) of the
Clean Air Act are the substances listedin Tables 1, 2, 3, and 4. Threshold quantities for listed toxic and flammable substances are specified in the tables.

(b) The basis for placing toxic and
flammable substances on the list of regulated substances are explained in
the notes to the list. § 68.130

T ABLE 1 TO § 68.130.—L IST OF R EGULATED

T OXIC S UBSTANCES AND T HRESHOLD Q UAN

TITIES FOR A CCIDENTAL R ELEASE P REVENTION
[Alphabetical Order—77 Substances]

Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

Acrolein [2­ 107–02–8 5,000 b

Propenal]

. Acrylonitrile [2­ 107–13–1 20,000 b

Propenenitrile]

. Acrylyl chloride [2­ 814–68–6 5,000 b

Propenoyl chloride]

. Allyl alcohol [2­ 107–18–61 15,000 b

Propen-l-ol]

. Allylamine [2­ 107–11–9 10,000 b

Propen-l-amine]

. Ammonia (anhy­ 7664–41–7 10,000 a, b

drous)

. Ammonia (conc 7664–41–7 20,000 a, b

20% or greater)

. Arsenous tri­ 7784–34–1 15,000 b

chloride

. Arsine

.................. 7784–42–1 1,000 b
Boron trichloride 10294–34–5 5,000 b

[Borane, trichloro-]

. Boron trifluoride 7637–07–2 5,000 b

[Borane, trifluoro-]

. Boron trifluoride 353–42–4 15,000 b

compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane]]-, T-4-

. Bromine

............... 7726–95–6 10,000 a, b Carbon disulfide

.. 75–15–0 20,000 b Chlorine

............... 7782–50–5 2,500 a, b Chlorine dioxide 10049–04–4 1,000 c

[Chlorine oxide (ClO2)]

. Chloroform [Meth­ 67–66–3 20,000 b

ane, trichloro-]

. Chloromethyl 542–88–1 1,000 b

ether [Methane, oxybis[chloro-]

. Chloromethyl 107–30–2 5,000 b

methyl ether [Methane, chloromethoxy-]

. Crotonaldehyde 4170–30–3 20,000 b

[2-Butenal]

. Crotonaldehyde, 123–73–9 20,000 b

(E)- [2-Butenal, (E)-]

. Cyanogen chlo­ 506–77–4 10,000 c

ride

. Cyclohexylamine 108–91–8 15,000 b

[Cyclohexanamine]

. Diborane

.............. 19287–45–7 2,500 b Dimethyldichloros­ 75–78–5 5,000 b

ilane [Silane,
dichlorodimethyl-]

. 1,1­ 57–14–7 15,000 b

Dimethylhydrazine [Hydrazine, 1,1-dimethyl-]

.

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T ABLE 1 TO § 68.130.—L IST OF R EGULATED T ABLE 1 TO § 68.130.—L IST OF R EGULATED

T OXIC S UBSTANCES AND T HRESHOLD Q UAN

- T OXIC S UBSTANCES AND T HRESHOLD Q UAN

TITIES FOR A CCIDENTAL R ELEASE P REVEN

- TITIES FOR A CCIDENTAL R ELEASE P REVEN

TION —Continued TION —Continued

[Alphabetical Order—77 Substances] [Alphabetical Order—77 Substances]

Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

Epichlorohydrin 106–89–8 20,000 b

[Oxirane, (chloromethyl)-]

. Ethylenediamine 107–15–3 20,000 b

[1,2­ Ethanediamine]

. Ethyleneimine 151–56–4 10,000 b

[Aziridine]

. Ethylene oxide 75–21–8 10,000 a, b

[Oxirane]

. Fluorine

............... 7782–41–4 1,000 b Formaldehyde 50–00–0 15,000 b

(solution)

. Furan

................... 110–00–9 5,000 b Hydrazine

............ 302–01–2 15,000 b Hydrochloric acid 7647–01–0 15,000 d

(conc 37% or greater)

. Hydrocyanic acid 74–90–8 2,500 a, b Hydrogen chloride 7647–01–0 5,000 a

(anhydrous) [Hydrochloric acid]

. Hydrogen fluoride/ 7664–39–3 1,000 a, b

Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid]

. Hydrogen sele­ 7783–07–5 500 b

nide

. Hydrogen sulfide 7783–06–4 10,000 a, b Iron, 13463–40–6 2,500 b

pentacarbonyl­ [Iron carbonyl(Fe(CO)5), (TB5-11)-]

. Isobutyronitrile 78–82–0 20,000 b

[Propanenitrile, 2-methyl-]

. Isopropyl 108–23–6 15,000 b

chloroformate[Carbonochloridic acid, 1­ methylethyl ester]

. Methacrylonitrile 126–98–7 10,000 b

[2­ Propenenitrile, 2-methyl-]

. Methyl chloride 74–87–3 10,000 a

[Methane, chloro-]

. Methyl 79–22–1 5,000 b

chloroformate[Carbonochloridic acid, methylester]

. Methyl hydrazine 60–34–4 15,000 b

[Hydrazine, methyl-]

. Methyl isocyanate 624–83–9 10,000 a, b

[Methane, isocyanato-]

. Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

Methyl mercaptan 74–93–1 10,000 b

[Methanethiol]

. Methyl 556–64–9 20,000 b

thiocyanate [Thiocyanic acid, methyl ester]

. Methyltrichlorosil­ 75–79–6 5,000 b

ane [Silane, trichloromethyl-]

. Nickel carbonyl

.... 13463–39–3 1,000 b Nitric acid (conc 7697–37–2 15,000 b

80% or greater)

. Nitric oxide [Nitro­ 10102–43–9 10,000 b

gen oxide (NO)]

. Oleum (Fuming 8014–95–7 10,000 e

Sulfuric acid) [Sulfuric acid,
mixture with sulfur trioxide] 1

. Peracetic acid 79–21–0 10,000 b

[Ethaneperoxoic acid]

. Perchloromethyl­ 594–42–3 10,000 b

mercaptan[Methanesulfenyl chloride, trichloro-]

. Phosgene [Car­ 75–44–5 500 a, b

bonic dichloride]

. Phosphine

........... 7803–51–2 5,000 b Phosphorus 10025–87–3 5,000 b

oxychloride [Phosphoryl chloride]

. Phosphorus tri­ 7719–12–2 15,000 b

chloride [Phosphorous trichloride]

. Piperidine

............ 110–89–4 15,000 b Propionitrile 107–12–0 10,000 b

[Propanenitrile]

. Propyl 109–61–5 15,000 b

chloroformate[Carbonochloridic acid, propylester]

. Propyleneimine 75–55–8 10,000 b

[Aziridine, 2­ methyl-]

. Propylene oxide 75–56–9 10,000 b

[Oxirane, methyl-]

. Sulfur dioxide (an­ 7446–09–5 5,000 a, b

hydrous)

. Sulfur tetrafluoride 7783–60–0 2,500 b

[Sulfur fluoride (SF4), (T-4)-]

. Sulfur trioxide

...... 7446–11–9 10,000 a, b Tetramethyllead 75–74–1 10,000 b

[Plumbane, tetramethyl-]

. Tetranitromethane 509–14–8 10,000 b

[Methane, tetranitro-]

.

58VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00055 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T Environmental Protection Agency § 68.130

T ABLE 1 TO § 68.130.—L IST OF R EGULATED T ABLE 1 TO § 68.130.—L IST OF R EGULATED

T OXIC S UBSTANCES AND T HRESHOLD Q UAN

- T OXIC S UBSTANCES AND T HRESHOLD Q UAN

TITIES FOR A CCIDENTAL R ELEASE P REVEN

- TITIES FOR A CCIDENTAL R ELEASE P REVEN

TION —Continued TION —Continued

[Alphabetical Order—77 Substances] [Alphabetical Order—77 Substances]

Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

Titanium tetra­ 7550–45–0 2,500 b

chloride [Titanium chloride (TiCl4) (T-4)-]

. Toluene 2,4­ 584–84–9 10,000 a

diisocyanate [Benzene, 2,4­ diisocyanato-1­ methyl-] 1

. Toluene 2,6­ 91–08–7 10,000 a

diisocyanate [Benzene, 1,3­ diisocyanato-2­ methyl-] 1

. Toluene 26471–62–5 10,000 a

diisocyanate (unspecifiedisomer) [Benzene, 1,3­diisocyanatomethyl-] 1

. Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

Trimethylchlorosil­ 75–77–4 10,000 b

ane [Silane, chlorotrimethyl-]

. Vinyl acetate 108–05–4 15,000 b

monomer [Acetic acid ethenyl ester]

.

1 The mixture exemption in § 68.115(b)(1) does not apply to the substance.

N OTE : Basis for Listing:

a Mandated for listing by Congress.
b On EHS list, vapor pressure 10 mmHg or greater.

c Toxic gas.
d Toxicity of hydrogen chloride, potential to release hydrogen chloride, and history of accidents.

e Toxicity of sulfur trioxide and sulfuric acid, potential to release sulfur trioxide, and history of accidents.

T ABLE 2 TO § 68.130.—L IST OF R EGULATED T OXIC S UBSTANCES AND T HRESHOLD Q UANTITIES FOR A CCIDENTAL R ELEASE P REVENTION

[CAS Number Order—77 Substances]

CAS No. Chemical name Threshold quantity

(lbs) Basis for listing

50–00–0

..................... 57–14–7

..................... 60–34–4

..................... 67–66–3

..................... 74–87–3

..................... 74–90–8

..................... 74–93–1

..................... 75–15–0

..................... 75–21–8

..................... 75–44–5

..................... 75–55–8

..................... 75–56–9

..................... 75–74–1

..................... 75–77–4

..................... 75–78–5

..................... 75–79–6

..................... 78–82–0

..................... 79–21–0

..................... 79–22–1

..................... 91–08–7

..................... 106–89–8

................... 107–02–8

................... 107–11–9

................... 107–12–0

................... 107–13–1

................... 107–15–3

................... 107–18–6

................... 107–30–2

................... 108–05–4

................... 108–23–6

................... 108–91–8

................... 109–61–5

................... 110–00–9

................... 110–89–4

................... 123–73–9

................... Formaldehyde (solution)

.................................................................................... 1,1-Dimethylhydrazine [Hydrazine, 1,1-dimethyl-]

............................................. Methyl hydrazine [Hydrazine, methyl-]

.............................................................. Chloroform [Methane, trichloro-]

........................................................................ Methyl chloride [Methane, chloro-]

.................................................................... Hydrocyanic acid

............................................................................................... Methyl mercaptan [Methanethiol]

...................................................................... Carbon disulfide

................................................................................................. Ethylene oxide [Oxirane]

................................................................................... Phosgene [Carbonic dichloride]

......................................................................... Propyleneimine [Aziridine, 2-methyl-]

................................................................ Propylene oxide [Oxirane, methyl-]

................................................................... Tetramethyllead [Plumbane, tetramethyl-]

......................................................... Trimethylchlorosilane [Silane, chlorotrimethyl-]

................................................. Dimethyldichlorosilane [Silane, dichlorodimethyl-]

............................................ Methyltrichlorosilane [Silane, trichloromethyl-]

.................................................. Isobutyronitrile [Propanenitrile, 2-methyl-]

......................................................... Peracetic acid [Ethaneperoxoic acid]

................................................................ Methyl chloroformate [Carbonochloridic acid, methylester]

.............................. Toluene 2,6-diisocyanate [Benzene, 1,3-diisocyanato-2-methyl-] 1

................... Epichlorohydrin [Oxirane, (chloromethyl)-]

........................................................ Acrolein [2-Propenal]

......................................................................................... Allylamine [2-Propen-1-amine]

.......................................................................... Propionitrile [Propanenitrile]

............................................................................... Acrylonitrile [2-Propenenitrile]

............................................................................ Ethylenediamine [1,2-Ethanediamine]

............................................................... Allyl alcohol [2-Propen-1-ol]

............................................................................... Chloromethyl methyl ether [Methane, chloromethoxy-]

..................................... Vinyl acetate monomer [Acetic acid ethenyl ester]

........................................... Isopropyl chloroformate [Carbonochloridic acid, 1-methylethyl ester]

.............. Cyclohexylamine [Cyclohexanamine]

................................................................ Propyl chloroformate [Carbonochloridic acid, propylester]

................................ Furan

.................................................................................................................. Piperidine

........................................................................................................... Crotonaldehyde, (E)- [2-Butenal, (E)-]

............................................................... 15,000 15,000 15,000 20,000 10,000 2,500 10,000 20,000 10,000

500 10,000 10,000 10,000 10,000 5,000 5,000 20,000 10,000 5,000 10,000 20,000 5,000 10,000 10,000 20,000 20,000 15,000 5,000 15,000 15,000 15,000 15,000 5,000 15,000 20,000 b
b
b
b

a a, b
b
b a, b a, b
b
b
b
b
b
b
b
b
b

a b
b
b
b
b
b
b
b
b
b
b
b
b
b
b

59VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00056 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T § 68.130 40 CFR Ch. I (7–1–98 Edition)

T ABLE 2 TO § 68.130.—L IST OF R EGULATED T OXIC S UBSTANCES AND T HRESHOLD Q UANTITIES FOR A CCIDENTAL R ELEASE P REVENTION —Continued

[CAS Number Order—77 Substances]

CAS No. Chemical name Threshold quantity

(lbs) Basis for listing

126–98–7

................... 151–56–4

................... 302–01–2

................... 353–42–4

...................

506–77–4

................... 509–14–8

................... 542–88–1

................... 556–64–9

................... 584–84–9

................... 594–42–3

................... 624–83–9

................... 814–68–6

................... 4170–30–3

................. 7446–09–5

................. 7446–11–9

................. 7550–45–0

................. 7637–07–2

................. 7647–01–0

................. 7647–01–0

................. 7664–39–3

................. 7664–41–7

................. 7664–41–7

................. 7697–37–2

................. 7719–12–2

................. 7726–95–6

................. 7782–41–4

................. 7782–50–5

................. 7783–06–4

................. 7783–07–5

................. 7783–60–0

................. 7784–34–1

................. 7784–42–1

................. 7803–51–2

................. 8014–95–7

................. 10025–87–3

............... 10049–04–4

............... 10102–43–9

............... 10294–34–5

............... 13463–39–3

............... 13463–40–6

............... 19287–45–7

............... 26471–62–5

............... Methacrylonitrile [2-Propenenitrile, 2-methyl-]

................................................... Ethyleneimine [Aziridine]

................................................................................... Hydrazine

........................................................................................................... Boron trifluoride compound with methyl ether (1:1) [Boron,

trifluoro[oxybis[methane]]-, T-4-

. Cyanogen chloride

............................................................................................. Tetranitromethane [Methane, tetranitro-]

........................................................... Chloromethyl ether [Methane, oxybis[chloro-]

................................................... Methyl thiocyanate [Thiocyanic acid, methyl ester]

........................................... Toluene 2,4-diisocyanate [Benzene, 2,4-diisocyanato-1-methyl-] 1

................... Perchloromethylmercaptan [Methanesulfenyl chloride, trichloro-]

..................... Methyl isocyanate [Methane, isocyanato-]

........................................................ Acrylyl chloride [2-Propenoyl chloride]

.............................................................. Crotonaldehyde [2-Butenal]

............................................................................... Sulfur dioxide (anhydrous)

................................................................................. Sulfur trioxide

..................................................................................................... Titanium tetrachloride [Titanium chloride (TiCl4) (T-4)-]

................................... Boron trifluoride [Borane, trifluoro-]

................................................................... Hydrochloric acid (conc 37% or greater)

........................................................... Hydrogen chloride (anhydrous) [Hydrochloric acid]

.......................................... Hydrogen fluoride/Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid] Ammonia (anhydrous)

....................................................................................... Ammonia (conc 20% or greater)

....................................................................... Nitric acid (conc 80% or greater)

...................................................................... Phosphorus trichloride [Phosphorous trichloride]

.............................................. Bromine

.............................................................................................................. Fluorine

.............................................................................................................. Chlorine

.............................................................................................................. Hydrogen sulfide

................................................................................................ Hydrogen selenide

............................................................................................. Sulfur tetrafluoride [Sulfur fluoride (SF4), (T-4)-]

.............................................. Arsenous trichloride

........................................................................................... Arsine

................................................................................................................. Phosphine

.......................................................................................................... Oleum (Fuming Sulfuric acid) [Sulfuric acid, mixture with sulfur trioxide] 1

....... Phosphorus oxychloride [Phosphoryl chloride]

................................................. Chlorine dioxide [Chlorine oxide (ClO 2 )]

........................................................... Nitric oxide [Nitrogen oxide (NO)]

..................................................................... Boron trichloride [Borane, trichloro-]

.................................................................. Nickel carbonyl

.................................................................................................. Iron, pentacarbonyl- [Iron carbonyl (Fe(CO) 5 ), (TB-5-11)-]

............................... Diborane

............................................................................................................Toluene diisocyanate (unspecified isomer) [Benzene, 1,3-diisocyanatomethyl1] 1

. 10,000 10,000 15,000 15,000

10,000 10,000 1,000 20,000 10,000 10,000 10,000 5,000 20,000 5,000 10,000 2,500 5,000 15,000 5,000 1,000 10,000 20,000 15,000 15,000 10,000 1,000 2,500 10,000

500 2,500 15,000 1,000 5,000 10,000 5,000 1,000 10,000 5,000 1,000 2,500 2,500 10,000 b
b
b
b

c b
b
b

a b a, b
b
b a, b a, b
b
b
d

a a, b a, b a, b
b
b a, b
b a, b a, b
b
b
b
b
b

e b

c b
b
b
b
b

a

1 The mixture exemption in § 68.115(b)(1) does not apply to the substance. N OTE : Basis for Listing:

a Mandated for listing by Congress. b On EHS list, vapor pressure 10 mmHg or greater.

c Toxic gas. d Toxicity of hydrogen chloride, potential to release hydrogen chloride, and history of accidents.

e Toxicity of sulfur trioxide and sulfuric acid, potential to release sulfur trioxide, and history of accidents.

T ABLE 3 TO § 68.130.—L IST OF R EGULATED F LAMMABLE S UBSTANCES AND T HRESHOLD Q UANTITIES

FOR A CCIDENTAL R ELEASE P REVENTION
[Alphabetical Order—63 Substances]

Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

Acetaldehyde

.................................................................................................................. Acetylene [Ethyne]

.......................................................................................................... Bromotrifluorethylene [Ethene, bromotrifluoro-]

.............................................................. 1,3-Butadiene

.................................................................................................................. Butane

............................................................................................................................. 1-Butene

......................................................................................................................... 2-Butene

......................................................................................................................... Butene

............................................................................................................................. 75–07–0
74–86–2
598–73–2
106–99–0
106–97–8
106–98–9
107–01–7
25167–67–3 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 g f
f
f
f
f
f
f

60VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00057 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T Environmental Protection Agency § 68.130

T ABLE 3 TO § 68.130.—L IST OF R EGULATED F LAMMABLE S UBSTANCES AND T HRESHOLD Q UANTITIES

FOR A CCIDENTAL R ELEASE P REVENTION —Continued

[Alphabetical Order—63 Substances]

Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

2-Butene-cis

.................................................................................................................... 2-Butene-trans [2-Butene, (E)]

....................................................................................... Carbon oxysulfide [Carbon oxide sulfide (COS)]

........................................................... Chlorine monoxide [Chlorine oxide]

............................................................................... 2-Chloropropylene [1-Propene, 2-chloro-]

...................................................................... 1-Chloropropylene [1-Propene, 1-chloro-]

...................................................................... Cyanogen [Ethanedinitrile]

.............................................................................................. Cyclopropane

.................................................................................................................. Dichlorosilane [Silane, dichloro-]

.................................................................................... Difluoroethane [Ethane, 1,1-difluoro-]

............................................................................. Dimethylamine [Methanamine, N-methyl-]

..................................................................... 2,2-Dimethylpropane [Propane, 2,2-dimethyl-]

............................................................... Ethane

............................................................................................................................. Ethyl acetylene [1-Butyne]

.............................................................................................. Ethylamine [Ethanamine]

................................................................................................ Ethyl chloride [Ethane, chloro-]

...................................................................................... Ethylene [Ethene]

........................................................................................................... Ethyl ether [Ethane, 1,1’-oxybis-]

................................................................................... Ethyl mercaptan [Ethanethiol]

......................................................................................... Ethyl nitrite [Nitrous acid, ethyl ester]

............................................................................. Hydrogen

........................................................................................................................ Isobutane [Propane, 2-methyl]

....................................................................................... Isopentane [Butane, 2-methyl-]

...................................................................................... Isoprene [1,3-Butadinene, 2-methyl-]

............................................................................. Isopropylamine [2-Propanamine]

.................................................................................... Isopropyl chloride [Propane, 2-chloro-]

.......................................................................... Methane

.......................................................................................................................... Methylamine [Methanamine]

........................................................................................... 3-Methyl-1-butene

........................................................................................................... 2-Methyl-1-butene

........................................................................................................... Methyl ether [Methane, oxybis-]

..................................................................................... Methyl formate [Formic acid, methyl ester]

.................................................................... 2-Methylpropene [1-Propene, 2-methyl-]

........................................................................ 1,3-Pentadinene

.............................................................................................................. Pentane

........................................................................................................................... 1-Pentene

....................................................................................................................... 2-Pentene, (E)­

............................................................................................................... 2-Pentene, (Z)­

............................................................................................................... Propadiene [1,2-Propadiene]

.......................................................................................... Propane

.......................................................................................................................... Propylene [1-Propene]

.................................................................................................... Propyne [1-Propyne]

....................................................................................................... Silane

.............................................................................................................................. Tetrafluoroethylene [Ethene, tetrafluoro-]

....................................................................... Tetramethylsilane [Silane, tetramethyl-]

......................................................................... Trichlorosilane [Silane, trichloro-]

................................................................................... Trifluorochloroethylene [Ethene, chlorotrifluoro-]

............................................................ Trimethylamine [Methanamine, N,N-dimethyl-]

.............................................................. Vinyl acetylene [1-Buten-3-yne]

...................................................................................... Vinyl chloride [Ethene, chloro-]

....................................................................................... Vinyl ethyl ether [Ethene, ethoxy-]

................................................................................. Vinyl fluoride [Ethene, fluoro-]

........................................................................................ Vinylidene chloride [Ethene, 1,1-dichloro-]

..................................................................... Vinylidene fluoride [Ethene, 1,1-difluoro-]

...................................................................... Vinyl methyl ether [Ethene, methoxy-]

........................................................................... 590–18–1

624–64–6

463–58–1

7791–21–1

557–98–2

590–21–6

460–19–5

75–19–4

4109–96–0

75–37–6

124–40–3

463–82–1

74–84–0

107–00–6

75–04–7

75–00–3

74–85–1

60–29–7

75–08–1

109–95–5

1333–74–0

75–28–5

78–78–4

78–79–5

75–31–0

75–29–6

74–82–8

74–89–5

563–45–1

563–46–2

115–10–6

107–31–3

115–11–7

504–60–9

109–66–0

109–67–1

646–04–8

627–20–3

463–49–0

74–98–6

115–07–1

74–99–7

7803–62–5

116–14–3

75–76–3

10025–78–2

79–38–9

75–50–3

689–97–4

75–01–4

109–92–2

75–02–5

75–35–4

75–38–7

107–25–5 10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000 f

f

f

f

g

g
f

f

f

f

f

f

f

f

f

f

f

g

g
f

f

f

g

g

g

g
f

f

f

g
f

g
f

f

g

g

g

g
f

f

f

f

f

f

g

g
f

f

f a, f

g
f

g
f

f

N OTE : Basis for Listing:

a Mandated for listing by Congress.
f Flammable gas.

g Volatile flammable liquid.

61VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00058 Fmt 8010 Sfmt 8006 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T § 68.130 40 CFR Ch. I (7–1–98 Edition)

T ABLE 4 TO § 68.130.—L IST OF R EGULATED F LAMMABLE S UBSTANCES AND T HRESHOLD Q UANTITIES

FOR A CCIDENTAL R ELEASE P REVENTION

[CAS Number Order—63 Substances]

CAS No. Chemical name CAS No. Threshold quantity

(lbs) Basis for listing

60–29–7

..................... 74–82–8

..................... 74–84–0

..................... 74–85–1

..................... 74–86–2

..................... 74–89–5

..................... 74–98–6

..................... 74–99–7

..................... 75–00–3

..................... 75–01–4

..................... 75–02–5

..................... 75–04–7

..................... 75–07–0

..................... 75–08–1

..................... 75–19–4

..................... 75–28–5

..................... 75–29–6

..................... 75–31–0

..................... 75–35–4

..................... 75–37–6

..................... 75–38–7

..................... 75–50–3

..................... 75–76–3

..................... 78–78–4

..................... 78–79–5

..................... 79–38–9

..................... 106–97–8

................... 106–98–9

................... 196–99–0

................... 107–00–6

................... 107–01–7

................... 107–25–5

................... 107–31–3

................... 109–66–0

................... 109–67–1

................... 109–92–2

................... 109–95–5

................... 115–07–1

................... 115–10–6

................... 115–11–7

................... 116–14–3

................... 124–40–3

................... 460–19–5

................... 463–49–0

................... 463–58–1

................... 463–82–1

................... 504–60–9

................... 557–98–2

................... 563–45–1

................... 563–46–2

................... 590–18–1

................... 590–21–6

................... 598–73–2

................... 624–64–6

................... 627–20–3

................... 646–04–8

................... 689–97–4

................... 1333–74–0

................. 4109–96–0

................. 7791–21–1

................. 7803–62–5

................. 10025–78–2

............... 25167–67–3

............... Ethyl ether [Ethane, 1,1 ′ -oxybis-]

........................................... Methane

................................................................................. Ethane

.................................................................................... Ethylene [Ethene]

................................................................... Acetylene [Ethyne]

................................................................. Methylamine [Methanamine]

.................................................. Propane

.................................................................................. Propyne [1-Propyne]

.............................................................. Ethyl chloride [Ethane, chloro-]

.............................................. Vinyl chloride [Ethene, chloro-]

.............................................. Vinyl fluoride [Ethene, fluoro-]

................................................ Ethylamine [Ethanamine]

....................................................... Acetaldehyde

.......................................................................... Ethyl mercaptan [Ethanethiol]

................................................ Cyclopropane

......................................................................... Isobutane [Propane, 2-methyl]

............................................... Isopropyl chloride [Propane, 2-chloro-]

.................................. Isopropylamine [2-Propanamine]

........................................... Vinylidene chloride [Ethene, 1,1-dichloro-]

............................ Difluoroethane [Ethane, 1,1-difluoro-]

.................................... Vinylidene fluoride [Ethene, 1,1-difluoro-]

.............................. Trimethylamine [Methanamine, N, N-dimethyl-]

..................... Tetramethylsilane [Silane, tetramethyl-]

................................. Isopentane [Butane, 2-methyl-]

.............................................. Isoprene [1,3,-Butadiene, 2-methyl-]

...................................... Trifluorochloroethylene [Ethene, chlorotrifluoro-]

................... Butane

.................................................................................... 1-Butene

................................................................................. 1,3-Butadiene

......................................................................... Ethyl acetylene [1-Butyne]

..................................................... 2-Butene

................................................................................. Vinyl methyl ether [Ethene, methoxy-]

................................... Methyl formate [Formic acid, methyl ester]

........................... Pentane

.................................................................................. 1-Pentene

............................................................................... Vinyl ethyl ether [Ethene, ethoxy-]

......................................... Ethyl nitrite [Nitrous acid, ethyl ester]

.................................... Propylene [1-Propene]

........................................................... Methyl ether [Methane, oxybis-]

............................................. 2-Methylpropene [1-Propene, 2-methyl-]

............................... Tetrafluoroethylene [Ethene, tetrafluoro-]

.............................. Dimethylamine [Methanamine, N-methyl-]

............................. Cyanogen [Ethanedinitrile]

..................................................... Propadiene [1,2-Propadiene]

................................................. Carbon oxysulfide [Carbon oxide sulfide (COS)]

................... 2,2-Dimethylpropane [Propane, 2,2-dimethyl-]

...................... 1,3-Pentadiene

....................................................................... 2-Chloropropylene [1-Propene, 2-chloro-]

............................. 3-Methyl-1-butene

.................................................................. 2-Methyl-1-butene

.................................................................. 2-Butene-cis

........................................................................... 1-Chloropropylene [1-Propene, 1-chloro-]

............................. Bromotrifluorethylene [Ethene, bromotrifluoro-]

..................... 2-Butene-trans [2-Butene, (E)]

............................................... 2-Pentene, (Z)-

....................................................................... 2-Pentene, (E)-

....................................................................... Vinyl acetylene [1-Buten-3-yne]

............................................. Hydrogen

................................................................................ Dichlorosilane [Silane, dichloro-]

............................................ Chlorine monoxide [Chlorine oxide]

....................................... Silane

..................................................................................... Trichlorosilane [Silane,trichloro-]

............................................ Butene

.................................................................................... 60–29–7
74–82–8
74–84–0
74–85–1
74–86–2
74–89–5
74–98–6
74–99–7
75–00–3
75–01–4
75–02–5
75–04–7
75–07–0
75–08–1
75–19–4
75–28–5
75–29–6
75–31–0
75–35–4
75–37–6
75–38–7
75–50–3
75–76–3
78–78–4
78–79–5
79–38–9
106–97–8
106–98–9
106–99–0
107–00–6
107–01–7
107–25–5
107–31–3
109–66–0
109–67–1
109–92–2
109–95–5
115–07–1
115–10–6
115–11–7
116–14–3
124–40–3
460–19–5
463–49–0
463–58–1
463–82–1
504–60–9
557–98–2
563–45–1
563–46–2
590–18–1
590–21–6
598–73–2
624–64–6
627–20–3
646–04–8
689–97–4
1333–74–0
4109–96–0
7791–21–1
7803–62–5
10025–78–2
25167–67–3 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 10,000 g f
f
f
f
f
f
f
f a, f
f
f

g
g f
f

g
g
g f
f
f

g
g
g f
f
f
f
f
f
f

g
g
g
g f
f
f
f
f
f
f
f
f
f
f

g f

g f

g f
f

g
g f
f
f
f
f

g f

Note: Basis for Listing: a Mandated for listing by Congress. f Flammable gas. g Volatile flammable liquid.
[59 FR 4493, Jan. 31, 1994. Redesignated at 61 FR 31717, June 20, 1996, as amended at 62 FR 45132, Aug. 25, 1997; 63 FR 645, Jan. 6, 1998]

62VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00059 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T Environmental Protection Agency

Subpart G—Risk Management Plan

S OURCE : 61 FR 31726, June 20, 1996, unless
otherwise noted.

§ 68.150 Submission.

(a) The owner or operator shall submit a single RMP that includes the information required by §§ 68.155 through
68.185 for all covered processes. The RMP shall be submitted in a methodand format to a central point as specified by EPA prior to June 21, 1999.

(b) The owner or operator shall submit the first RMP no later than the latest of the following dates:

(1) June 21, 1999; (2) Three years after the date on which a regulated substance is first listed under § 68.130; or

(3) The date on which a regulated
substance is first present above a threshold quantity in a process.

(c) Subsequent submissions of RMPs shall be in accordance with § 68.190.

(d) Notwithstanding the provisions of §§ 68.155 to 68.190, the RMP shall exclude classified information. Subject to appropriate procedures to protect such information from public disclosure, classified data or information excluded from the RMP may be made availablein a classified annex to the RMP for review by Federal and state representatives who have received the appropriate security clearances.

§ 68.155 Executive summary.

The owner or operator shall provide in the RMP an executive summary thatincludes a brief description of the following elements:

(a) The accidental release prevention and emergency response policies at the stationary source;

(b) The stationary source and regulated substances handled;

(c) The worst-case release scenario(s) and the alternative release scenario(s), including administrative controls andmitigation measures to limit the distances for each reported scenario;

(d) The general accidental releaseprevention program and chemical-specific prevention steps;

(e) The five-year accident history; § 68.165

(f) The emergency response program;
and

(g) Planned changes to improve safety.

§ 68.160 Registration.

(a) The owner or operator shall complete a single registration form and include it in the RMP. The form shall cover all regulated substances handled in covered processes.

(b) The registration shall include the following data:

(1) Stationary source name, street, city, county, state, zip code, latitude, and longitude;

(2) The stationary source Dun and Bradstreet number;

(3) Name and Dun and Bradstreetnumber of the corporate parent company;

(4) The name, telephone number, andmailing address of the owner or operator;

(5) The name and title of the person or position with overall responsibility for RMP elements and implementation;

(6) The name, title, telephone number, and 24-hour telephone number of the emergency contact;

(7) For each covered process, thename and CAS number of each regulated substance held above the threshold quantity in the process, the maximum quantity of each regulated substance or mixture in the process (in pounds) to two significant digits, the SIC code, and the Program level of the

process;

(8) The stationary source EPA identifier;

(9) The number of full-time employees at the stationary source;

(10) Whether the stationary source is subject to 29 CFR 1910.119;

(11) Whether the stationary source is subject to 40 CFR part 355;

(12) Whether the stationary source has a CAA Title V operating permit;
and

(13) The date of the last safety inspection of the stationary source by a Federal, state, or local governmentagency and the identity of the inspecting entity.

§ 68.165 Offsite consequence analysis.

(a) The owner or operator shall submit in the RMP information:

63VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00060 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T § 68.168

(1) One worst-case release scenario for each Program 1 process; and

(2) For Program 2 and 3 processes,one worst-case release scenario to represent all regulated toxic substances held above the threshold quantity andone worst-case release scenario to represent all regulated flammable substances held above the threshold quantity. If additional worst-case scenarios for toxics or flammables are required by § 68.25(a)(2)(iii), the owner or operator shall submit the same information

on the additional scenario(s). The owner or operator of Program 2 and 3 processes shall also submit information on one alternative release scenario for each regulated toxic substance held above the threshold quantity and one alternative release scenario to represent all regulated flammable substances held above the threshold quantity.

(b) The owner or operator shall submit the following data:

(1) Chemical name; (2) Physical state (toxics only); (3) Basis of results (give model name if used);

(4) Scenario (explosion, fire, toxic gasrelease, or liquid spill and vaporization);

(5) Quantity released in pounds; (6) Release rate; (7) Release duration; (8) Wind speed and atmospheric stability class (toxics only);

(9) Topography (toxics only); (10) Distance to endpoint; (11) Public and environmental receptors within the distance;

(12) Passive mitigation considered;
and

(13) Active mitigation considered (alternative releases only);

§ 68.168 Five-year accident history.

The owner or operator shall submit in the RMP the information provided in § 68.42(b) on each accident covered by § 68.42(a).

§ 68.170 Prevention program/Program 2.
(a) For each Program 2 process, the owner or operator shall provide in the
RMP the information indicated inparagraphs (b) through (k) of this sec40 CFR Ch. I (7–1–98 Edition)

tion. If the same information applies to more than one covered process, theowner or operator may provide the information only once, but shall indicateto which processes the information applies.

(b) The SIC code for the process. (c) The name(s) of the chemical(s)
covered.

(d) The date of the most recent review or revision of the safety information and a list of Federal or state regulations or industry-specific design
codes and standards used to demonstrate compliance with the safety information requirement.

(e) The date of completion of the most recent hazard review or update.

(1) The expected date of completionof any changes resulting from the hazard review;

(2) Major hazards identified; (3) Process controls in use; (4) Mitigation systems in use; (5) Monitoring and detection systems in use; and

(6) Changes since the last hazard review.

(f) The date of the most recent review or revision of operating procedures.

(g) The date of the most recent review or revision of training programs;

(1) The type of training provided— classroom, classroom plus on the job, on the job; and

(2) The type of competency testing
used.

(h) The date of the most recent review or revision of maintenance procedures and the date of the most recent equipment inspection or test and the equipment inspected or tested.

(i) The date of the most recent compliance audit and the expected date of completion of any changes resulting from the compliance audit.

(j) The date of the most recent incident investigation and the expecteddate of completion of any changes resulting from the investigation.

(k) The date of the most recentchange that triggered a review or revision of safety information, the hazardreview, operating or maintenance procedures, or training.

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§ 68.175 Prevention program/Program 3.
(a) For each Program 3 process, theowner or operator shall provide the information indicated in paragraphs (b) through (p) of this section. If the same information applies to more than one covered process, the owner or operator

may provide the information onlyonce, but shall indicate to which processes the information applies.

(b) The SIC code for the process. (c) The name(s) of the substance(s)
covered.

(d) The date on which the safety information was last reviewed or revised.

(e) The date of completion of the most recent PHA or update and the technique used.

(1) The expected date of completion of any changes resulting from the PHA;

(2) Major hazards identified; (3) Process controls in use; (4) Mitigation systems in use; (5) Monitoring and detection systems in use; and

(6) Changes since the last PHA. (f) The date of the most recent review or revision of operating procedures.

(g) The date of the most recent review or revision of training programs;

(1) The type of training provided— classroom, classroom plus on the job, on the job; and

(2) The type of competency testing
used.

(h) The date of the most recent review or revision of maintenance procedures and the date of the most recent equipment inspection or test and the equipment inspected or tested.

(i) The date of the most recent change that triggered management of change procedures and the date of themost recent review or revision of management of change procedures.

(j) The date of the most recent prestartup review.

(k) The date of the most recent compliance audit and the expected date of completion of any changes resulting from the compliance audit;

(l) The date of the most recent incident investigation and the expecteddate of completion of any changes resulting from the investigation;

(m) The date of the most recent review or revision of employee participation plans; § 68.190

(n) The date of the most recent review or revision of hot work permit procedures;

(o) The date of the most recent review or revision of contractor safety procedures; and

(p) The date of the most recent evaluation of contractor safety performance.

§ 68.180 Emergency response program.

(a) The owner or operator shall provide in the RMP the following information:

(1) Do you have a written emergency response plan?

(2) Does the plan include specific actions to be taken in response to an accidental releases of a regulated substance?

(3) Does the plan include procedures for informing the public and local agencies responsible for responding to accidental releases?

(4) Does the plan include information on emergency health care?

(5) The date of the most recent review or update of the emergency response plan;

(6) The date of the most recent emergency response training for employees.

(b) The owner or operator shall provide the name and telephone number of the local agency with which the plan is coordinated.

(c) The owner or operator shall list other Federal or state emergency plan requirements to which the stationary source is subject.

§ 68.185 Certification.

(a) For Program 1 processes, the owner or operator shall submit in theRMP the certification statement provided in § 68.12(b)(4).

(b) For all other covered processes, the owner or operator shall submit in the RMP a single certification that, tothe best of the signer’s knowledge, information, and belief formed after reasonable inquiry, the information submitted is true, accurate, and complete.

§ 68.190 Updates.

(a) The owner or operator shall review and update the RMP as specified in paragraph (b) of this section and
submit it in a method and format to a

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central point specified by EPA prior to June 21, 1999.

(b) The owner or operator of a stationary source shall revise and update the RMP submitted under § 68.150 as follows:

(1) Within five years of its initial submission or most recent update required by paragraphs (b)(2) through (b)(7) of this section, whichever is later.

(2) No later than three years after anewly regulated substance is first listed by EPA;

(3) No later than the date on which a

new regulated substance is first present in an already covered process above a threshold quantity;

(4) No later than the date on which a regulated substance is first present above a threshold quantity in a new

process;

(5) Within six months of a change that requires a revised PHA or hazard review;

(6) Within six months of a changethat requires a revised offsite consequence analysis as provided in § 68.36; and

(7) Within six months of a changethat alters the Program level that applied to any covered process.

(c) If a stationary source is no longersubject to this part, the owner or operator shall submit a revised registration to EPA within six months indicating that the stationary source is no longer covered.

Subpart H—Other Requirements

S OURCE : 61 FR 31728, June 20, 1996, unless
otherwise noted.

§ 68.200 Recordkeeping.

The owner or operator shall maintain records supporting the implementationof this part for five years unless otherwise provided in subpart D of this part.

§ 68.210 Availability of information to the public.
(a) The RMP required under subpart G of this part shall be available to the public under 42 U.S.C. 7414(c).

(b) The disclosure of classified information by the Department of Defenseor other Federal agencies or contractors of such agencies shall be con40 CFR Ch. I (7–1–98 Edition)

trolled by applicable laws, regulations,or executive orders concerning the release of classified information.

§ 68.215 Permit content and air permitting authority or designated agency requirements.
(a) These requirements apply to any stationary source subject to this part 68 and parts 70 or 71 of this chapter. The 40 CFR part 70 or part 71 permit for the stationary source shall contain:

(1) A statement listing this part as an applicable requirement;

(2) Conditions that require the source owner or operator to submit:

(i) A compliance schedule for meeting the requirements of this part by the date provided in § 68.10(a) or;

(ii) As part of the compliance certification submitted under 40 CFR 70.6(c)(5), a certification statement that the source is in compliance with all requirements of this part, including the registration and submission of the
RMP.

(b) The owner or operator shall submit any additional relevant information requested by the air permitting authority or designated agency.

(c) For 40 CFR part 70 or part 71 permits issued prior to the deadline for registering and submitting the RMPand which do not contain permit conditions described in paragraph (a) of this section, the owner or operator or airpermitting authority shall initiate permit revision or reopening according to the procedures of 40 CFR 70.7 or 71.7 to incorporate the terms and conditions consistent with paragraph (a) of this

section.

(d) The state may delegate the authority to implement and enforce the requirements of paragraph (e) of this section to a state or local agency or agencies other than the air permitting authority. An up-to-date copy of anydelegation instrument shall be maintained by the air permitting authority.The state may enter a written agreement with the Administrator under which EPA will implement and enforce the requirements of paragraph (e) of
this section.

(e) The air permitting authority or the agency designated by delegation or agreement under paragraph (d) of this section shall, at a minimum:

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(1) Verify that the source owner or operator has registered and submittedan RMP or a revised plan when required by this part;

(2) Verify that the source owner oroperator has submitted a source certification or in its absence has submitted a compliance schedule consistent with paragraph (a)(2) of this section;

(3) For some or all of the sources subject to this section, use one or more mechanisms such as, but not limitedto, a completeness check, source audits, record reviews, or facility inspections to ensure that permitted sourcesare in compliance with the requirements of this part; and

(4) Initiate enforcement action based on paragraphs (e)(1) and (e)(2) of this section as appropriate.

§ 68.220 Audits.

(a) In addition to inspections for the purpose of regulatory development andenforcement of the Act, the implementing agency shall periodically audit RMPs submitted under subpart G of this part to review the adequacy of such RMPs and require revisions ofRMPs when necessary to ensure compliance with subpart G of this part.

(b) The implementing agency shall select stationary sources for audits based on any of the following criteria:

(1) Accident history of the stationary

source;

(2) Accident history of other stationary sources in the same industry;

(3) Quantity of regulated substances present at the stationary source;

(4) Location of the stationary sourceand its proximity to the public and environmental receptors;

(5) The presence of specific regulated substances;

(6) The hazards identified in the RMP; and

(7) A plan providing for neutral, random oversight.

(c) Exemption from audits. A stationary source with a Star or Merit ranking under OSHA’s voluntary protection program shall be exempt from audits under paragraph (b)(2) and (b)(7) of this

section.

(d) The implementing agency shall have access to the stationary source, supporting documentation, and any § 68.220

area where an accidental release could

occur.

(e) Based on the audit, the implementing agency may issue the owner or operator of a stationary source a written preliminary determination of necessary revisions to the stationary source’s RMP to ensure that the RMP meets the criteria of subpart G of this part. The preliminary determination shall include an explanation for thebasis for the revisions, reflecting industry standards and guidelines (such as AIChE/CCPS guidelines and ASME and API standards) to the extent that suchstandards and guidelines are applicable, and shall include a timetable for their implementation.

(f) Written response to a preliminary determination. (1) The owner or operatorshall respond in writing to a preliminary determination made in accordance with paragraph (e) of this section. The response shall state the owner or operator will implement the revisionscontained in the preliminary determination in accordance with the timetable included in the preliminary determination or shall state that the owner or operator rejects the revisions in whole or in part. For each rejected revision, the owner or operator shallexplain the basis for rejecting such revision. Such explanation may include substitute revisions.

(2) The written response under paragraph (f)(1) of this section shall be received by the implementing agencywithin 90 days of the issue of the preliminary determination or a shorter period of time as the implementingagency specifies in the preliminary determination as necessary to protect public health and the environment. Prior to the written response being due and upon written request from the owner or operator, the implementingagency may provide in writing additional time for the response to be received.

(g) After providing the owner or operator an opportunity to respond underparagraph (f) of this section, the implementing agency may issue the owneror operator a written final determination of necessary revisions to the stationary source’s RMP. The final determination may adopt or modify the revisions contained in the preliminary

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determination under paragraph (e) of this section or may adopt or modify the substitute revisions provided in the response under paragraph (f) of this
section. A final determination that adopts a revision rejected by the owneror operator shall include an explanation of the basis for the revision. A final determination that fails to adopt a substitute revision provided underparagraph (f) of this section shall include an explanation of the basis forfinding such substitute revision unreasonable.

(h) Thirty days after completion ofthe actions detailed in the implementation schedule set in the final determination under paragraph (g) of this section, the owner or operator shall be 40 CFR Ch. I (7–1–98 Edition)

in violation of subpart G of this part and this section unless the owner or operator revises the RMP prepared under subpart G of this part as requiredby the final determination, and submits the revised RMP as required under § 68.150.

(i) The public shall have access to the preliminary determinations, responses, and final determinations under this section in a manner consistent with § 68.210.

(j) Nothing in this section shall preclude, limit, or interfere in any way with the authority of EPA or the stateto exercise its enforcement, investigatory, and information gathering authorities concerning this part under the Act.

68VerDate 25<JUN>98 07:40 Jul 22, 1998 Jkt 179149 PO 00000 Frm 00065 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm02 PsN: 179149T Environmental Protection Agency Pt. 68, App. AAPPENDIXATOPART68—TABLEOFTOXICENDPOINTS[As defined in §68.22 of this part]CAS No.Chemical nameToxic end­point (mg/L)107–02–8..........................................107–13–1..........................................814–68–6..........................................107–18–6..........................................107–11–9..........................................7664–41–7........................................7664–41–7........................................7784–34–1........................................7784–42–1........................................10294–34–5......................................7637–07–2........................................353–42–4..........................................7726–95–6........................................75–15–0............................................7782–50–5........................................10049–04–4......................................67–66–3............................................542–88–1..........................................107–30–2..........................................4170–30–3........................................123–73–9..........................................506–77–4..........................................108–91–8..........................................19287–45–7......................................75–78–5............................................57–14–7............................................106–89–8..........................................107–15–3..........................................151–56–4..........................................75–21–8............................................7782–41–4........................................50–00–0............................................110–00–9..........................................302–01–2..........................................7647–01–0........................................74–90–8............................................7647–01–0........................................7664–39–3........................................7783–07–5........................................7783–06–4........................................13463–40–6......................................78–82–0............................................108–23–6..........................................126–98–7..........................................Acrolein [2-Propenal]....................................................................................................................................................................................Acrylonitrile [2-Propenenitrile].......................................................................................................................................................................Acrylyl chloride [2-Propenoyl chloride].........................................................................................................................................................Allyl alcohol [2-Propen-1-ol]..........................................................................................................................................................................Allylamine [2-Propen-1-amine]......................................................................................................................................................................Ammonia (anhydrous)...................................................................................................................................................................................Ammonia (conc 20% or greater)..................................................................................................................................................................Arsenous trichloride......................................................................................................................................................................................Arsine............................................................................................................................................................................................................Boron trichloride [Borane, trichloro-].............................................................................................................................................................Boron trifluoride [Borane, trifluoro-]..............................................................................................................................................................Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro[oxybis[methane]]-, T-4......................................................................Bromine.........................................................................................................................................................................................................Carbon disulfide............................................................................................................................................................................................Chlorine.........................................................................................................................................................................................................Chlorine dioxide [Chlorine oxide (ClO2)]......................................................................................................................................................Chloroform [Methane, trichloro-]...................................................................................................................................................................Chloromethyl ether [Methane, oxybis[chloro-]..............................................................................................................................................Chloromethyl methyl ether [Methane, chloromethoxy-]................................................................................................................................Crotonaldehyde [2-Butenal]..........................................................................................................................................................................Crotonaldehyde, (E)-, [2-Butenal, (E)-].........................................................................................................................................................Cyanogen chloride........................................................................................................................................................................................Cyclohexylamine [Cyclohexanamine]...........................................................................................................................................................Diborane........................................................................................................................................................................................................Dimethyldichlorosilane [Silane, dichlorodimethyl-]........................................................................................................................................1,1-Dimethylhydrazine [Hydrazine, 1,1-dimethyl-]........................................................................................................................................Epichlorohydrin [Oxirane, (chloromethyl)-]...................................................................................................................................................Ethylenediamine [1,2-Ethanediamine]..........................................................................................................................................................Ethyleneimine [Aziridine]...............................................................................................................................................................................Ethylene oxide [Oxirane]...............................................................................................................................................................................Fluorine.........................................................................................................................................................................................................Formaldehyde (solution)...............................................................................................................................................................................Furan.............................................................................................................................................................................................................Hydrazine......................................................................................................................................................................................................Hydrochloric acid (conc 37% or greater)......................................................................................................................................................Hydrocyanic acid...........................................................................................................................................................................................Hydrogen chloride (anhydrous) [Hydrochloric acid].....................................................................................................................................Hydrogen fluoride/Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid]...........................................................................................Hydrogen selenide........................................................................................................................................................................................Hydrogen sulfide...........................................................................................................................................................................................Iron, pentacarbonyl- [Iron carbonyl (Fe(CO)5), (TB–5–11)-]........................................................................................................................Isobutyronitrile [Propanenitrile, 2-methyl-]....................................................................................................................................................Isopropyl chloroformate [Carbonochloride acid, 1-methylethyl ester]..........................................................................................................Methacrylonitrile [2-Propenenitrile, 2-methyl-]..............................................................................................................................................0.00110.0760.000900.0360.00320.140.140.0100.00190.0100.0280.0230.00650.160.00870.00280.490.000250.00180.0290.0290.0300.160.00110.0260.0120.0760.490.0180.0900.00390.0120.00120.0110.0300.0110.0300.0160.000660.0420.000440.140.100.0027

69VerDate 25<JUN>98 14:03 Jul 30, 1998 Jkt 179149 PO 00000 Frm 00066 Fmt 8010 Sfmt 8010 Y:\SGML\179149T.XXX pfrm07 PsN: 179149T Pt. 68, App. A 40 CFR Ch. I (7–1–98 Edition)

70APPENDIXATOPART68—TABLEOFTOXICENDPOINTS—Continued[As defined in §68.22 of this part]CAS No.Chemical nameToxic end­point (mg/L)74–87–3............................................79–22–1............................................60–34–4............................................624–83–9..........................................74–93–1............................................556–64–9..........................................75–79–6............................................13463–39–3......................................7697–37–2........................................10102–43–9......................................8014–95–7........................................79–21–0............................................594–42–3..........................................75–44–5............................................7803–51–2........................................10025–87–3......................................7719–12–2........................................110–89–4..........................................107–12–0..........................................109–61–5..........................................75–55–8............................................75–56–9............................................7446–09–5........................................7783–60–0........................................7446–11–9........................................75–74–1............................................509–14–8..........................................7750–45–0........................................584–84–9..........................................91–08–7............................................26471–62–5......................................75–77–4............................................108–05–4..........................................Methyl chloride [Methane, chloro-]...............................................................................................................................................................Methyl chloroformate [Carbonochloridic acid, methylester]..........................................................................................................................Methyl hydrazine [Hydrazine, methyl-].........................................................................................................................................................Methyl isocyanate [Methane, isocyanato-]...................................................................................................................................................Methyl mercaptan [Methanethiol]..................................................................................................................................................................Methyl thiocyanate [Thiocyanic acid, methyl ester]......................................................................................................................................Methyltrichlorosilane [Silane, trichloromethyl-].............................................................................................................................................Nickel carbonyl..............................................................................................................................................................................................Nitric acid (conc 80% or greater)..................................................................................................................................................................Nitric oxide [Nitrogen oxide (NO)].................................................................................................................................................................Oleum (Fuming Sulfuric acid) [Sulfuric acid, mixture with sulfur trioxide]....................................................................................................Peracetic acid [Ethaneperoxoic acid]...........................................................................................................................................................Perchloromethylmercaptan [Methanesulfenyl chloride, trichloro-]................................................................................................................Phosgene [Carbonic dichloride]....................................................................................................................................................................Phosphine.....................................................................................................................................................................................................Phosphorus oxychloride [Phosphoryl chloride].............................................................................................................................................Phosphorus trichloride [Phosphorous trichloride].........................................................................................................................................Piperidine......................................................................................................................................................................................................Propionitrile [Propanenitrile]..........................................................................................................................................................................Propyl chloroformate [Carbonochloridic acid, propylester]...........................................................................................................................Propyleneimine [Aziridine, 2-methyl-]...........................................................................................................................................................Propylene oxide [Oxirane, methyl-]..............................................................................................................................................................Sulfur dioxide (anhydrous)............................................................................................................................................................................Sulfur tetrafluoride [Sulfur fluoride (SF4), (T-4)-]..........................................................................................................................................Sulfur trioxide................................................................................................................................................................................................Tetramethyllead [Plumbane, tetramethyl-]....................................................................................................................................................Tetranitromethane [Methane, tetranitro-]......................................................................................................................................................Titanium tetrachloride [Titanium chloride (TiCl4) (T-4)-]..............................................................................................................................Toluene 2,4-diisocyanate [Benzene, 2,4-diisocyanato-1-methyl-]................................................................................................................Toluene 2,6-diisocyanate [Benzene, 1,3-diisocyanato-2-methyl-]................................................................................................................Toluene diisocyanate (unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-].........................................................................................Trimethylchlorosilane [Silane, chlorotrimethyl-]............................................................................................................................................Vinyl acetate monomer [Acetic acid ethenyl ester]......................................................................................................................................0.820.00190.00940.00120.0490.0850.0180.000670.0260.0310.0100.00450.00760.000810.00350.00300.0280.0220.00370.0100.120.590.00780.00920.0100.00400.00400.0200.00700.00700.00700.0500.26[61 FR 31729, June 20, 1996, as amended at 62 FR 45132, Aug. 25, 1997]963federal register 

### Wednesday January 6, 1999



# Part IV



# Environmental Protection Agency

40 CFR Part 68

Accidental Release Prevention Requirements; Risk Management Programs Under Clean Air Act Section 112(r)(7), Amendments; Final Rule

### 964 Federal Register / Vol. 64, No. 3 / Wednesday, January 6, 1999 / Rules and Regulations

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 68

[FRL–6214–9]

RIN 2050–AE46

Accidental Release Prevention Requirements; Risk Management Programs Under Clean Air Act Section 112(r)(7); Amendments

AGENCY : Environmental Protection Agency (EPA).

ACTION : Final rule.

SUMMARY : This action modifies the chemical accident prevention rule codified in 40 CFR Part 68. The chemical accident prevention rule requires owners and operators of stationary sources subject to the rule to submit a risk management plan (RMP) by June 21, 1999, to a central location specified by EPA. In this action, EPA is amending the rule to: add four mandatory and five optional RMP data elements, establish specific procedures for protecting confidential business information when submitting RMPs, adopt the government’s use of a new industry classification system, and make technical corrections and clarifications to Part 68. However, as stated in the proposed rule for these amendments, this action does not address issues concerning public access to offsite consequence analysis data in the RMP.

DATES : The rule is effective February 5,
1999.

ADDRESSES : Supporting material used in developing the proposed rule and final rule is contained in Docket A–98–08. The docket is available for public inspection and copying between 8:00

a.m. and 5:30 p.m., Monday through Friday (except government holidays) at Room 1500, 401 M Street SW, Washington, DC 20460. A reasonable fee may be charged for copying. FOR FURTHER INFORMATION CONTACT : Sicy Jacob or John Ferris, Chemical Emergency Preparedness and Prevention Office, Environmental Protection Agency (5104), 401 M Street SW, Washington, DC 20460, (202) 260– 7249 or (202) 260–4043, respectively; or the Emergency Planning and Community Right-to-Know Hotline at 800–424–9346 (in the Washington, DC metropolitan area, (703) 412–9810). You may wish to visit the Chemical Emergency Preparedness and Prevention Office (CEPPO) Internet site, at www.epa.gov/ceppo.

SUPPLEMENTARY INFORMATION :
Regulated Entities

Entities potentially regulated by this action are those stationary sources that have more than a threshold quantity of a regulated substance in a process. Regulated categories and entities include:

Category Examples of regulated entities

Chemical Manufacturers

..................................... Basic chemical manufacturing, petrochemicals, resins, agricultural chemicals, pharmaceuticals, paints, cleaning compounds.
Petroleum

............................................................ Refineries. Other Manufacturing

........................................... Paper, electronics, semiconductors, fabricated metals, industrial machinery, food processors. Agriculture

........................................................... Agricultural retailers. Public Sources

.................................................... Drinking water and waste water treatment systems.
Utilities

................................................................. Electric utilities. Other

................................................................... Propane retailers and users, cold storage, warehousing, and wholesalers. Federal Sources

.................................................. Military and energy installations.

This table is not meant to be exhaustive, but rather provides a guide for readers to indicate those entities likely to be regulated by this action. The table lists entities EPA is aware of that could potentially be regulated by this action. Other entities not listed in the table could also be regulated. To determine whether a stationary source is regulated by this action, carefully examine the provisions associated with the list of substances and thresholds under § 68.130 and the applicability criteria under § 68.10. If you have questions regarding applicability of this action to a particular entity, consult the hotline or persons listed in the preceding FOR FURTHER INFORMATION

CONTACT section.

Table of Contents

I. Introduction and Background

A. Statutory Authority
B. Background
II. Summary of the Final Rule
III. Discussion of Issues

A. NAICS Codes
B. RMP Data Elements
C. Prevention Program Reporting
D. Confidential Business Information
E. Other Issues F. Technical Corrections
IV. Section-by-Section Discussion of the Final Rule
V. Judicial Review
VI. Administrative Requirements

A. Docket
B. Executive Order 12866
C. Executive Order 12875
D. Executive Order 13045
E. Executive Order 13084
F. Regulatory Flexibility
G. Paperwork Reduction
H. Unfunded Mandates Reform Act
I. National Technology Transfer and

Advancement Act
J. Congressional Review Act

I. Introduction and Background

A. Statutory Authority

These amendments are being promulgated under sections 112(r) and 301(a)(1) of the Clean Air Act (CAA) as amended (42 U.S.C. 7412(r), 7601(a)(1)).

B. Background

The 1990 CAA Amendments added section 112(r) to provide for the prevention and mitigation of accidental chemical releases. Section 112(r) mandates that EPA promulgate a list of ‘‘regulated substances,’’ with threshold quantities. Processes at stationary sources that contain a threshold quantity of a regulated substance are subject to accidental release prevention regulations promulgated under CAA section 112(r)(7). EPA promulgated the list of regulated substances on January 31, 1994 (59 FR 4478) (the ‘‘List Rule’’) and the accidental release prevention regulations creating the risk management program requirements on June 20, 1996 (61 FR 31668) (the ‘‘RMP Rule’’). Together, these two rules are codified as 40 CFR Part 68. EPA amended the List Rule on August 25, 1997 (62 FR 45132), to change the listed concentration of hydrochloric acid. On January 6, 1998 ( 63 FR 640), EPA amended the List Rule to delist Division
1.1 explosives (classified by DOT), to clarify certain provisions related to regulated flammable substances and to clarify the transportation exemption.

Part 68 requires that sources with more than a threshold quantity of a regulated substance in a process develop and implement a risk management program that includes a five-year accident history, offsite consequence analyses, a prevention

### 965 Federal Register / Vol. 64, No. 3 / Wednesday, January 6, 1999 / Rules and Regulations

program, and an emergency response program. In Part 68, processes are divided into three categories (Programs 1 through 3). Processes that have no potential impact on the public in the case of accidental releases have minimal requirements (Program 1). Processes in Programs 2 and 3 have additional requirements based on the potential for offsite consequences associated with the worst-case accidental release and their accident history. Program 3 is also triggered if the processes are subject to OSHA’s Process Safety Management (PSM) Standard. By June 21, 1999, sources must submit to a location designated by EPA, a risk management plan (RMP) that summarizes their implementation of the risk management
program.

When EPA promulgated the risk management program regulations, it stated that it intended to work toward electronic submission of RMPs. The Accident Prevention Subcommittee of the CAA Advisory Committee convened an Electronic Submission Workgroup to examine technical and practical issues associated with creating a national electronic repository for RMPs. Based on workgroup recommendations, EPA is in the process of developing two systems, a user-friendly PC-based submission system (RMP*Submit) and a database of RMPs (RMP*Info).

The Electronic Submission Workgroup also recommended that EPA add some mandatory and optional data elements to the RMP and asked EPA to clarify how confidential business information (CBI) submitted in the RMP would be handled. Based on these recommendations and requests for clarifications, EPA proposed amendments to Part 68 on April 17, 1998 (63 FR 19216). These amendments proposed to replace the use of Standard Industrial Classification (SIC) codes with the North American Industry Classification System (NAICS) codes, add four mandatory data elements to the RMP, add five optional data elements to the RMP, establish specific requirements for submission of information claimed CBI, and make technical corrections and clarifications to the rule. EPA received 47 written comments on the proposed rule. Today’s rule reflects EPA’s consideration of all comments; major issues raised by commenters and EPA’s responses are discussed in Section III of this preamble. A summary of all comments submitted and EPA’s responses can be found in a document entitled, Accidental Release Prevention Requirements; Risk Management Programs Under Clean Air Act Section 112(r)(7); Amendments: Summary and Response to Comments, in the Docket (see ADDRESSES ).

II. Summary of the Final Rule

NAICS Codes

On January 1, 1997, the U.S. Government, in cooperation with the governments of Canada and Mexico, adopted a new industry classification system, the North American Industry Classification System (NAICS), to replace the Standard Industrial Classification (SIC) codes (April 9, 1997, 62 FR 17288). The applicability of some Part 68 requirements (i.e., Program 3 prevention requirements) is determined, in part, by SIC codes, and Part 68 also requires the reporting of SIC codes in the RMP. Therefore, EPA is revising Part 68 to replace all references to ‘‘SIC code’’ with ‘‘NAICS code.’’ In addition, EPA is replacing, as proposed, the nine SIC codes subject to Program 3 prevention program requirements with ten NAICS codes, as follows:

NAICS Sector
32211 Pulp mills
32411 Petroleum refineries
32511 Petrochemical manufacturing
325181 Alkalies and chlorine
325188 All other inorganic chemical manufacturing
325192 Other cyclic crude and intermediate manufacturing
325199 All other basic organic chemical manufacturing
325211 Plastics and resins
325311 Nitrogen fertilizer
32532 Pesticide and other agricultural chemicals NAICS codes are either five or six digits, depending on the degree to which the sector is subdivided.

RMP Data Elements

As proposed, EPA is adding four new data elements to the RMP: latitude/ longitude method and description, CAA Title V permit number, percentage weight of a toxic substance in a liquid mixture, and NAICS code for each process that had an accidental release reported in the five-year accident history. EPA is also adding five optional data elements: local emergency planning committee (LEPC) name, source or parent company e-mail address, source homepage address, phone number at the source for public inquiries, and status under OSHA’s Voluntary Protection Program (VPP).

Prevention Program Reporting

EPA is not revising Sections 68.170 and 68.175 as proposed. Prevention program reporting, therefore, will not be changed to require a prevention program for each portion of a process for which a Process Hazard Analysis (PHA) or hazard review was conducted. Instead, EPA plans to create functions within RMP*Submit to provide stationary sources with a flexible way of explaining the scope and content of each prevention program they implement at their facility.

Confidential Business Information

EPA is clarifying how confidential business information (CBI) submitted in the RMP will be handled. EPA has determined that the information required by certain RMP data elements does not meet the criteria for CBI and therefore may not be claimed as such. The Agency is also requiring submission of substantiation at the time a CBI claim is filed.

Finally, EPA is promulgating several of the technical corrections and clarifications, as proposed in the Federal Register , April 17, 1998 (63 FR 19216).

III. Discussion of Issues

EPA received 47 comments on the proposed rule. The commenters included chemical manufacturers, petroleum refineries, environmental groups, trade associations, a state agency, and members of the public. The major issues raised by commenters are addressed briefly below. The Agency’s complete response to comments received on this rulemaking is available in the docket (see ADDRESSES ). The document is titled Accidental Release Prevention Requirements; Risk Management Programs Under Clean Air Act Section 112(r)(7); Amendments: Summary and Response to Comments.

A. NAICS Codes

Two commenters asked that sources be given the option to use either SIC codes or NAICS codes, or both, in their initial RMP because the NAICS system is new and may not be familiar to sources. EPA disagrees with this suggestion. EPA intends to provide several outreach mechanisms to assist sources in identifying their new NAICS code. RMP*Submit will provide a ‘‘pick list’’ that will make it easier for sources to find the appropriate code. Also, selected NAICS codes are included in the General Guidance for Risk Management Programs (July 1998) and in the industry-specific guidance documents that EPA is developing. EPA will also utilize the Emergency Planning and Community Right-to-Know Hotline at 800–424–9346 (or 703–412–9810) and its web site at www.epa.gov/ceppo/, to assist sources in determining the source’s NAICS codes. EPA also notes that the Internal Revenue Service is planning to require businesses to

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provide NAICS-based activity codes on their 1998 tax returns, so many sources will have become familiar with their NAICS codes by the June 1999 RMP deadline.

EPA believes it is necessary and appropriate to change from SIC codes to NAICS codes at this time. EPA recognizes that NAICS codes were developed for statistical purposes by the Office of Management and Budget (OMB). In the notice of April 9, 1997 (62 FR 17288) OMB stated that the ‘‘[u]se of NAICS for nonstatistical purposes (e.g., administrative, regulatory, or taxation) will be determined by the agency or agencies that have chosen to use the SIC for nonstatistical purposes.’’ EPA has determined that NAICS is appropriate in this rule for several reasons. First, the reason the SIC codes were replaced by NAICS codes is because the SIC codes no longer accurately represent today’s industries. The SIC codes will become more obsolete over time because OMB will no longer be supporting the SIC codes; therefore, no new or modified SIC codes will be developed to reflect future changes in industries. Second, as the SIC codes become obsolete, most users of SIC codes will likely change to NAICS codes over time, so future data sharing and consistency will be enhanced by use of NAICS codes in the RMP program. Third, through this rulemaking process, EPA has analyzed specific conversions of SIC codes to NAICS codes for the RMP program and was able to identify NAICS codes that were applicable to fulfilling the purposes of this rule. Finally, because the RMP reporting requirement is new, it is reasonable to begin the program with NAICS codes now rather than converting to them later.

Three commenters expressed support for the ten NAICS codes that EPA proposed to use in place of the nine SIC codes referenced in section 68.10(d)(1) of Part 68 and one commenter partially objected. Section 68.10(d)(1) provides that processes in the referenced codes are subject to Program 3 requirements (if not eligible for Program 1). One commenter objected to EPA’s proposal to replace the SIC code for pulp and paper mills with only the NAICS code for pulp mills that do not also produce paper or paperboard. The commenter asked EPA to reexamine the accident history of paper and paperboard mills. As discussed in the preamble of the proposed rule, EPA reviewed the accident history data prior to proposing the new NAICS codes. Neither facilities that classify themselves as paper mills (NAICS Code 322121) nor paperboard mills (NAICS code 32213) met the accident history criteria that EPA used to select industrial sectors for Program
3. EPA notes that a pulp process at a paper or a paperboard mill may still be subject to Program 3 as long as the process contains more than a threshold quantity of a regulated substance and is not eligible for Program 1. Section 68.10(d)(1) uses industrial codes to classify processes, not facilities as a whole. Since section 68.10(d)(1) will continue to list the code for pulp mills, pulpmaking processes will continue to be subject to Program 3. In addition, under section 68.10(d)(2), paper processes will be in Program 3 (unless eligible for Program 1) if they are subject to OSHA’s Process Safety Management (PSM) standard. Most pulp and paper processes are, in fact, subject to this standard.

One commenter objected to assigning NAICS codes to a process rather than the source as a whole. EPA first notes that the requirement to assign a SIC code to a process was adopted in the original RMP rulemaking two years ago. Today’s rule does not change that requirement except to substitute NAICS for SIC codes. In any event, EPA is today modifying Part 68 to clarify that sources provide the NAICS code that ‘‘most closely corresponds to the process.’’ EPA believes that assigning an industry code to a process will help implementing agencies and the public understand what the covered process does; using the code makes it possible to provide this information without requiring a detailed explanation from the source. In addition, the primary NAICS code for a source as a whole may not reflect the activity of the covered

process.

B. RMP Data Elements

EPA proposed to add, as optional RMP data elements: local emergency planning committee (LEPC), source (or parent company) E-mail address, source homepage address, phone number at the source for public inquiries, and OSHA Voluntary Protection Program (VPP) status. EPA also proposed to add, as mandatory data elements: method and description of latitude/longitude, Title V permit number, percent weight of a toxic substance in a liquid mixture, and NAICS code (only in the five-year accident history section).

Commenters generally supported the new optional data elements. One commenter requested that the optional elements be made mandatory. EPA disagrees with this comment. While the elements are useful, many sources covered by this rule will not have e-mail addresses or home pages. The RMP will provide both addresses and phone numbers so that the public will have methods to reach the source. EPA has learned that in some areas there are no functioning LEPCs, therefore, at this time, EPA will not add this as a mandatory data element. However, in most cases, the LEPC for an area can be determined by contacting the local government or the State Emergency Response Commission (SERC) for which the area is located. Therefore, reporting these data elements will remain optional at this time.

One commenter supported adding the listing of local emergency planning committee in the RMP data elements as an optional data element. The commenter stated that, although it is an optional data element, this listing will enhance the ability of local responders and emergency planners to adequately prepare and train for emergency events.

Of the data elements that were proposed to be mandatory, one commenter objected to the addition of latitude/longitude method and description. The commenter stated that it was not clear in the proposal why the method and description information is needed. EPA is seeking latitude/ longitude method and description in accordance with its Locational Data Policy. Several EPA regulations require sources to provide their latitude and longitude, so that EPA can more readily locate facilities and communicate data between Agency offices. Sharing of data between EPA offices reduces duplication of information. Latitude/ longitude method and description provides information needed by EPA offices, and other users of the data, to rectify discrepancies that may appear in the latitude and longitude information provided by the source under various EPA requirements. Documentation of the method by which the latitude and longitude are determined and a description of the location point referenced by the latitude and longitude (e.g., administration building) will permit data users to evaluate the accuracy of those coordinates, thus addressing EPA data sharing and integration objectives.

EPA believes this information will also facilitate EPA-State coordination of environmental programs, including the chemical accident prevention rule. The State/EPA Data Management Program is a successful multi-year initiative linking State environmental regulatory agencies and EPA in cooperative action. The Program’s goals include improvements in data quality and data integration based on location identification. Therefore, as proposed, the latitude/ longitude method and description will be added to the existing RMP data

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elements. RMP*Submit will provide a list of methods and descriptions from which sources may choose.

EPA also proposed to require that sources report the percentage weight (weight percent) of a toxic substance in a mixture in the offsite consequence analysis (OCA) and the accident history sections of the RMP. This information is necessary for users of RMP data to understand how worst case and alternative release scenarios have been modeled. EPA has decided to require reporting of the weight percent of toxic substance in a liquid mixture because this information is necessary to understand the volatilization rate, which determines the downwind dispersion distance of the substance. The volatilization rate is affected by the vapor pressure of the substance in the mixture. For example, a spill of 70 percent hydrofluoric acid (HF) will volatilize more quickly than a spill of the same quantity of HF in a 50 percent solution; consequently, over a 10­ minute period, the 70 percent solution will travel further. Reviewers of the RMP data, including local emergency planning committees, need to know the weight percent to be able to evaluate the results reported in the offsite consequence analysis and the impacts reported in the accident history. Without knowing the weight percent of the substance in the mixture, users of the data may compare scenarios or incidents that appear to involve the same chemical in the same physical state, but in fact involve the same chemical held in a different physical

state.

One commenter stated that for gas mixtures, percentage by volume (or volume percent) should be required to be reported rather than weight percent. In this final rule, EPA does not require reporting of the weight percent (or volume percent) of a regulated substance in a gas mixture. If a source handles regulated substances in a gaseous mixture (e.g., chlorine with hydrogen chloride), the quantity of a particular regulated substance in the mixture is what is reported in the RMP, since that is what would be released into the air. Its percentage weight in the mixture is irrelevant.

Another commenter objected to this data element, claiming that it could result in reverse engineering and create a competitive disadvantage. EPA does not believe that this requirement would create a competitive disadvantage, since similar information is available to the public under Emergency Planning and Community Right-to-Know Act (EPCRA) of 1986. Even so, if it were to have such an effect, sources can claim this element as CBI if it can meet the criteria for CBI claims in 40 CFR Part 2. Another commenter stated that the public would be concerned if the percentages did not add to 100, in the event that the sourcehandles both regulated and nonregulated substances. EPA believes that because a source must model only one substance in a release scenario, the source need not report the percentages of the other substances in the mixture. Therefore, it is expected that the weight percent for mixtures would not always add up to 100, because the mixture could contain non-regulated substances.

A third commenter suggested that requiring sources to report percentage weight of a toxic substance in a liquid mixture would create confusion with the reporting of mixtures containing flammable regulated substances.

In the January 6, 1998 rule (63 FR 640), EPA clarified that flammable regulated substances in mixtures are only covered by the RMP rule if the entire mixture meets the National Fire Protection Association (NFPA) criteria of 4, thus the entire mixture becomes the regulated substance. As a result, the percentage of flammables in a mixture is not relevant under the rule and the requirement to report the percentage weight will only apply to toxic substances in a liquid mixture.

Finally, in the Federal Register notice of June 20, 1996 (61 FR 31688), EPA clarified the relationship between the risk management program and the air permit program under Title V of the CAA for sources subject to both requirements. Under section 502(b)(5)(A), permitting authorities must have the authority to assure compliance by all covered sources with each applicable CAA standard, regulation or requirement, including the regulations implementing section 112(r)(7). Requiring sources covered by Title V and section 112(r) to provide their Title V permit number will help Title V permitting authorities assure that each source is complying with the RMP rule.

In summary, with the exception of adding the phrase ‘‘that most closely corresponds to the process’’ in sections 68.42(b)(4), 68.160(b)(7), 68.170(b), and 68.175(b), EPA has decided to finalize the optional and mandatory data elements as they were proposed.

C. Prevention Program Reporting

The final RMP rule, issued June 20, 1996 (61 FR 31668), requires sources to report their prevention program for each ‘‘process.’’ Because the applicable definition of ‘‘process’’ is broad, multiple production and storage units might be a single, complex ‘‘process.’’ However, the Agency realizes that some elements of a source’s prevention program for a process may not be applicable to every portion of the process. In such a situation, reporting prevention program information for the process as a whole could be misleading without an explanation of which prevention program element applies to which part of the process. In order to get more specific information on which prevention program practices apply to different production and storage units within a process, EPA proposed to revise the rule to require prevention program reporting for each part of the process for which a separate process hazard analysis (PHA) or hazard review was conducted. EPA further proposed deleting the second sentence from both sections 68.170(a) and 68.175(a), which presently states that, ‘‘[i]f the same information applies to more than one covered process, the owner or operator may provide the information only once, but shall indicate to which process the information applies.’’

A number of industry commenters objected to the proposed revisions as wrongly assuming that a one-to-one relationship exists between a prevention program and a PHA. The commenters asserted that EPA’s proposed revision did not reflect how facilities conduct PHAs or implement prevention measures and would cause significant duplicate reporting, creating unnecessary extra work for facility personnel. One commenter explained that depending on a source’s circumstances, it might conduct a PHA for each production line, including all of its different units, or it might conduct a PHA for each common element of its different production lines. Accordingly, the commenters claimed that EPA’s proposal to require the owner/operator to submit separate prevention program information for every portion of a process covered by a PHA would result in multiple submissions of much of the same material, and would add no value to process safety or accidental release prevention. Commenters also opposed the deletion of the second sentence in sections 68.170(a) and 68.175(a). One commenter noted that many of the elements of the prevention program will not only be common to a process, but will be common to an entire stationary source. Thus commenters argued that EPA’s proposals would result in redundant submittals and place an unjustified burden on the regulated community.

EPA acknowledges that PHAs do not necessarily determine the scope of prevention program measures. Moreover, EPA agrees that duplicative

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reporting should be reduced as much as possible. At the same time, EPA, implementing agencies, and other users of RMP data need to have information that is detailed enough to understand the hazards posed by, and the safety practices used for, particular parts of processes and equipment. EPA recognizes that some aspects of prevention programs are likely to be implemented facility-wide, rather than on a process or unit basis, whereas other aspects may apply to a particular process or only to particular units within a process. For example, most sources are likely to develop an employee participation plan and asystem for hot work permits facilitywide, rather than on a process or unit basis. For sources having processes that include several units (e.g., multiple reactors or purification systems), the hazards, process controls, and mitigation systems may vary among the individual units. For example, one may have a deluge fire control system while another may have a runaway reaction quench system.

EPA has concluded that its proposed changes to prevention program reporting would not lead sources to prepare RMPs that accurately and efficiently communicate the hazards posed by different aspects of covered processes and the safety practices used to address those hazards. The Agency now believes that no rule changes are necessary to ensure that RMPs convey that information. The current rule already requires prevention program reporting, and the issue has been how to efficiently convey that information in sufficient detail. EPA believes that its electronic program for submitting RMPs can be designed to provide for sufficient specificity in prevention program reporting without requiring duplicative reporting. In particular, the Agency plans to create a comment/text field in RMP*Submit for specifying which parts of a prevention program apply to which portions of a particular process. For example, if a deluge system only applies to a certain part of the overall process, the source would indicate in the comment/text screen the portions of the process to which the deluge system applies.

To reduce the burden of reporting, EPA also plans to create a function in RMP*Submit which will allow a source to automatically copy prevention program data previously entered for one process to fill blank fields in another process’s prevention program. The source could then edit any of the data elements that are different. For example, where the prevention programs for two processes are identical (e.g., two identical storage tanks that are considered separate processes), the source could copy the data entered for one to fill in the blank field for the other. If some of the data elements vary between the prevention programs, the source will be able to autofill and change only those items that vary among processes or units.

Although the autofill option will minimize the burden of reporting common data elements for those sources filing electronically, EPA has decided not to delete the sentence, in both sections 68.170(a) and 68.175(a), which states, ‘‘[i]f the same information applies to more than one covered process, the owner or operator may provide the information only once, but shall indicate to which processes the information applies ’’, as proposed.

D. Confidential Business Information (CBI)

1. Background

A central element of the chemical accident prevention program as established by the Clean Air Act and implemented by Part 68 is providing state and local governments and the public with information about the risk of chemical accidents in their communities and what stationary sources are doing to prevent such accidents. As explained in the preamble to the final RMP rule (61 FR 31668, June 20, 1996), every covered stationary source is required to develop and implement a risk management program and provide information about that program in its RMP. Under CAA section 112(r)(7)(B)(iii), a source’s RMP must be registered with EPA and also submitted to the Federal Chemical Safety and Hazard Investigation Board (‘‘the Board’’), the state in which the source is located, and any local entity responsible for emergency response or planning. That section also provides that RMPs ‘‘shall be available to the public under section 114(c)’’ of the CAA. Section 114(c) gives the public access to information obtained under the Clean Air Act except for information (other than emission data) that would divulge trade secrets.

As noted previously, in the final RMP rule EPA announced its plan to develop a centralized system for submitting electronic versions of RMPs that would reduce the paperwork burden on both industry and receiving agencies and provide ready public access to RMP data. Under the system, a covered source would submit its RMP on computer diskette, which would be entered into a central database that all interested parties could access electronically. The system would thus make it possible for a single RMP submission to reach all interested parties, including those identified in section 112(r)(7)(B)(iii). 1

An important assumption underlying the Agency’s central submission plan was that RMPs would rarely, if ever, contain confidential business information (CBI). Following publication of the final rule, concerns were raised that at least some of the information required to be reported in RMPs could be CBI in the case of particular sources. While the June 20, 1996 rule provided for protection of CBI under section 114(c) (see section 68.210(a)), EPA was asked to address how CBI would be protected in the context of the electronic programs being developed for RMP submission and public access.

In the April 17, 1998 proposal to revise the RMP rule, EPA made several proposals concerning protection of CBI. It first reviewed the information requirements for RMPs (sections 68.155–185) and proposed to find that certain required data elements would not entail divulging information that could meet the test for CBI set forth in the Agency’s comprehensive CBI regulations at 40 CFR Part 2. 2 Information provided in response to those requirements could not be claimed CBI. EPA also requested comment on whether some information that might be claimed as CBI (e.g., worst-case release rate or duration) would be ‘‘emission data’’ and thus publicly available under section 114(c) even if CBI.

EPA administers a variety of statutes pertaining to the protection of the environment, each with its own data collection requirements and requirements for disclosure of information to the public. In the implementation of these statutes, the Agency collects emission, chemical, process, waste stream, financial, and other data from facilities in many, if not most, sectors of American business. Companies may consider some of this information vital to their competitive

1 It is important to note that, as discussed in Section III. E of this preamble, this rule does not address issues concerning public access to offsite consequence analysis data in the RMP.

2 Information is CBI if (1) the business has asserted a claim which has not expired, been waived, or been withdrawn; (2) the business has
shown that it has taken and will continue to take reasonable steps to protect the information from disclosure; (3) the information is not and has not been reasonably obtainable by the public (other than governmental bodies) by use of legitimate means; (4) no statute requires disclosure of the information; and (5) disclosure of the information is likely to cause substantial harm to the business’ competitive position. 40 CFR section 2.208.

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position, and claim it as confidential business information (CBI).

In the course of implementing statutes, the Agency may have a need to communicate some or all of the information it collects to the public as the basis for a rulemaking, to its contractors, or in response to requests pursuant to the Freedom of Information Act (FOIA). Information found to be CBI is exempt from disclosure under FOIA. To manage both CBI claims and FOIA requests, EPA has promulgated in 40 CFR Part 2, Subpart B a set of procedures for reviewing CBI claims, releasing information found not to be CBI, and where authorized, disclosing CBI. Subpart B lists the criteria that information must meet in order to be considered CBI, as well as the special handling requirements the Agency must follow when disclosing CBI to authorized representatives.

For RMP requirements that might entail divulging CBI, EPA proposed that a source be required to substantiate a CBI claim to EPA at the time that it makes the claim. Under EPA’s Part 2 regulations, a source claiming CBI generally is required to substantiate the claim only when EPA needs to make the information public as part of some proceeding (e.g., a rulemaking) or EPA receives a request from the public (e.g., under the Freedom of Information Act (FOIA)) for the information. In view of the public information function of RMPs and the interest already expressed by members of the public in them, EPA proposed ‘‘up-front substantiation’’ of CBI claims to ensure that information not meeting CBI criteria would be made available to the public as soon aspossible. This approach of requiring upfront substantiation is the same as that used for trade secret claims filed under the Emergency Planning and Community Right-to-Know Act (EPCRA) of 1986. 3

3 Section 302 of EPCRA (codified in 40 CFR Part 355) requires any facility having more than a threshold planning quantity of an extremely hazardous substance (EHS) to notify its state emergency response commission (SERC) and local emergency planning committee (LEPC) that the facility is subject to emergency planning. The vast majority of toxic substances listed in 40 CFR
Section 68.130 were taken from the EHS list. Section 303 of EPCRA requires LEPCs to prepare an emergency response plan for the community that is under their jurisdiction. Section 303 of EPCRA also requires that facilities subject to section 302 shall provide any information required by their LEPC necessary for developing and implementing the emergency plan. Section 304 of EPCRA requires an
immediate notification of a release of an EHS or
Hazardous Substances listed in 40 CFR Section
302.4 above a reportable quantity to state and localentities. Section 304 also requires a written followup which includes among other things, the chemical name, quantity released and any known or anticipated health risks associated with the In addition, EPA proposed that any source claiming CBI submit two versions of its RMP: (1) a redacted (‘‘sanitized’’), electronic version, which would become part of RMP*Info, and (2) an unsanitized (unredacted) paper copy of the RMP (see proposed section 68.151(c)). The electronic database of RMPs would contain only the redacted version unless and until EPA ruled against all or part of the source’s CBI claim, in keeping with the Part 2 procedures. In this way, the public would have access only to the non-CBI elements of sources’ RMPs. EPA further stated that state and local agencies could receive the unredacted RMPs by requesting them from EPA under the Part 2 regulations. Those regulations authorize EPA to provide CBI to an agency having implementation responsibilities under the CAA if the agency either demonstrates that it has the authority under state or local law to compel such information directly from the source or that it will ‘‘provide adequate protection to the interests of affected businesses’’ (40 CFR 2.301(h)(3)).

The following sections of this preamble summarize and respond to thecomments EPA received on the CBIrelated aspects of its proposal. At the outset, however, EPA wants to emphasize that it does not anticipate many CBI claims being made in connection with RMPs. The Agency developed the RMP data elements with the issue of CBI in mind. It sought to define data elements that would provide basic information about a source’s risk management program without requiring it to reveal CBI. To have done otherwise would have risked creating RMPs that were largely unavailable to the public. EPA continues to believe that the required RMP data elements will rarely require that a business divulge CBI. The Agency will carefully monitor the CBI claims made. If it appears that the number of claims being made is jeopardizing the public information

release. Sections 311 and 312 of EPCRA (codified in 40 CFR Part 370) require facilities that are subject to OSHA Hazard Communication Standard (HCS), to provide information to its SERC, LEPC and local fire department. This information includes the hazards posed by its chemicals, and inventory information, including average daily amount, maximum quantity and general location. Section 313 of EPCRA (codified in 40 CFR Part 372) requires certain facilities that are in specific industries (including chemical manufacturers) and that manufacture, process, or otherwise use a toxic chemical above specified threshold amounts to report, among other things, the annual quantity of the toxic chemical entering each environmental medium. Most facilities covered by CAA 112(r) are covered by one or more of these sections of EPCRA. Section 322 of EPCRA (codified in Part 350) allows facilities to claim only the chemical identity as
trade secret. objective of the chemical accident prevention program, EPA will consider ways of revising RMPs, including further rulemakings or revising the underlying program, to ensure that important health and safety information is available to the public.

2. RMP Data Elements Found Not CBI

Fifteen commenters representing environmental groups and members of the public opposed allowing some or all RMP data to be claimed as CBI in light of the public’s interest in the information RMPs will provide. A number of commenters urged EPA not to allow the following RMP data elements (and supporting documents) to be claimed as CBI:

• Mitigation measures considered by the firm in its offsite consequence analysis,

• Major process hazards identified by the firm,

• Process controls in use,

• Mitigation systems in use,

• Monitoring and detection systems in use, and

• Changes since the last hazard

review.

In addition, one commenter contended that even chemical identity and quantity should be ineligible for CBI protection, since the requirement to submit an RMP only applies to facilities using a few well-known, extremely hazardous chemicals, and the public’s right to know should always outweigh a company’s claim to CBI.

Along the same lines, a number of commenters urged EPA to develop a ‘‘corporate sunshine rule’’ that would allow confidentiality concerns to be overridden if the protected information is needed by the public and experts to understand and assess safety issues. Another commenter recommended that a business claiming a chemical’s identity as CBI should be required to provide the generic name of the chemical and information about its adverse health effects so the public can determine the potential risks.

One commenter argued that some of the RMP data that EPA suggested could reveal CBI, (e.g., release rate), were not ‘‘emission data,’’ because the worst case scenario data are theoretical estimates, and do not represent any real emissions, past or present.

Representatives of the chemical and petroleum industries disagreed with EPA’s proposal to list the data elements that EPA believed could not reveal CBI in any case. These commenters asserted that EPA could not anticipate all the ways in which information required by a data element might reveal CBI, and accordingly urged the Agency to make

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case-by-case determinations on CBI claims. They also contended that ‘‘emission data’’ under section 114(c) does not extend to data on possible, as opposed to actual, emissions, and thus that RMP information concerning potential accidental releases would not qualify as ‘‘emission data,’’ which must be made available to the public.

As pointed out above, an important purpose of the chemical accident prevention program required by section 112(r) is to inform the public of the risk of accidents in their communities and the methods sources are employing to reduce such risks. EPA therefore believes that as much RMP data as possible should be available to the public as soon as possible. However, section 112(r)(7)(B)(iii) requires that RMPs be made ‘‘available to the public under section 114(c),’’ which provides for protection of trade secret information (other than emission data). Given the statute’s direction to protect whatever trade secret information is contained in an RMP, EPA is not authorized to release such information even when the public’s need for such information arguably outweighs a business’ interest in its confidentiality. The Agency also cannot issue a ‘‘corporate sunshine rule’’ that conflicts with existing law requiring EPA (and other agencies) to protect trade secret information.

As explained above (and in more detail in the proposed rule), EPA examined each RMP data element to determine which would require information that might, depending on a business’ circumstances, meet the CBI criteria set forth in EPA’s regulations implementing section 114(c) and other information-related legal requirements. The point of this exercise was to both protect potential trade secret information and promote the public information purpose of RMPs by identifying which RMP information might reveal CBI in a particular case and by precluding CBI claims for information that could not reveal CBI in any case. EPA presented the results of its analysis and an explanation of why certain data elements could entail the reporting of CBI depending on a business’ circumstances and why others could not. No commenter provided any specific examples or explanations that contradicted the Agency’s rationale for its determinations of which data elements could or could not result in reporting of CBI.

However, EPA is deleting from the list of 40 CFR Part 68.151(b)(1) the reference to 40 CFR Part 68.160(b)(9), to allow forthe possibility of the number of fulltime employees at the stationary source to be claimed as CBI. Upon further review, EPA was unable to determine that providing the number of employees at the stationary source could never entail divulging information that could meet the test for CBI set forth in the Agency’s comprehensive CBI regulations at 40 CFR Part 2. Therefore, EPA has removed this element from the list of data elements that can not be claimed CBI in Part 68. With this exception, EPA is promulgating the list of RMP data elements for which CBI claims are precluded, as proposed (Section 68.151(b)).

EPA’s justifications for its specific CBI findings appear in an appendix to this preamble. A more detailed analysis of all RMP data elements and CBI determinations is available in the docket (see ADDRESSES ). The Agency continues to find no reasonable basis for anticipating that the listed elements will in any case require a business to reveal CBI that is not ‘‘emission data.’’ The information required by each of the listed data elements either fails to meet the criteria for CBI set forth in EPA’s CBI regulations at Part 2 or meets the Part 2 definition of ‘‘emission data.’’ In many cases, the information is available to the public through other reports filed with EPA, states, or local agencies (e.g., reports required by Emergency Planning and Community Right-to-Know Act (EPCRA) sections 312 and 313 provide general facility identification information and reports of most accidental releases are available through several Federal databases including EPA’s Emergency Release Notification System and Accidental Release Information Program databases).

In order to preclude CBI claims for other data elements, the Agency would have to show that the information required by a data element either was ‘‘emission data’’ under section 114(c) or could not, under any circumstances, reveal CBI. As explained below, EPA does not believe such a showing can be made for any of the data elements not on the list. Therefore, CBI claims made for information required by data elements not on the list will be evaluated on a case-by-case basis according to the procedures contained in 40 CFR Part 2 (except that substantiation will have to accompany the claims, as discussed below).

The Agency agrees with the commenters who argued that information about potential accidental releases is not ‘‘emission data’’ under section 114(c). EPA’s existing policy statement (see 56 FR 7042, Feb. 21, 1991) on what information may be considered ‘‘emission data’’ was developed to implement sections 110 and 114(a) of the CAA, which the Agency generally invokes when it seeks to gather technical data from a source
about its actual emissions to the air. While the policy is not explicitly limited in its scope, EPA believes it would be inappropriate to apply it to RMP data elements concerning hypothetical, as opposed to actual,
releases to the air. Under the definition of ‘‘emission data’’ contained in Part 2, information is ‘‘emission data’’ if it is (1) ‘‘necessary to determine the identity, amount, frequency, concentration, or
other characteristics * * * of any

emission which has been emitted by the source,’’ (2) ‘‘necessary to determine the identity, amount, frequency, concentration, or other characteristics
* * * of the emissions which, under an applicable standard or limitation, the

source was authorized to emit ;’’ or (3) general facility identification information regarding the source which distinguishes it from other sources (40 CFR section 2.301(a)(2)(i) (emphasis added)). Under these criteria, EPA has concluded that only the RMP data elements relating to source-level registration information (sections68.160(b)(1)–(6), (8)–(13)) and the fiveyear accident history (section 68.168)
are ‘‘emission data.’’ Of the RMP data elements, only the five-year accident history involves actual, past emissions to the environment; the other data elements would not, therefore, qualify as ‘‘emission data’’ under the first prong of the Part 2 definition. Moreover, the data elements relating to a source’s offsite consequence analysis, prevention program and emergency response program do not attempt to identify or otherwise reflect ‘‘authorized’’ emissions; the data elements instead reflect the source’s potential for accidental releases. Accordingly, these data elements would not be ‘‘emission data’’ under the second prong of the definition. As for the third prong, some of the source-level data are ‘‘emission data’’ because they help identify a source. Most other RMP data elements are reported on a process level and are not generally used to distinguish one source from another.

The Agency believes it is unable to show that the remaining data elements could not, under any circumstances, reveal CBI. EPA continues to believe that it is theoretically possible for the remaining data elements (the elements not listed in section 68.151(b)) to reveal CBI either directly or through reverse engineering, depending on the circumstances of a particular case. At the same time, EPA believes that, in practice, the remaining data elements will rarely reveal CBI. The purpose of

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the data in the RMP is for a source to articulate its hazards, and the steps it takes to prevent accidental releases. In general, the kinds of information specifying the source’s hazards and risk management program are not likely to be competitively sensitive.

In particular, covered processes at the vast majority of stationary sources subject to the RMP rule are too common and well-known to support a CBI claim for information related to such processes. For example, covered public drinking water and wastewater treatment plants generally use common regulated substances in standard processes (i.e., chlorine used for disinfection). Also, covered processes at many sources involve the storage of regulated substances that the sources sell (e.g., propane, ammonia), so the processes are already public knowledge. Other covered processes involve the use of well-known combinations of regulated substances such as refrigerants. RMP information regarding these types of processes should not include CBI.

Even in the case of unusual or unique processes, it is generally unlikely that RMP information could be used to reveal CBI through reverse engineering. To begin with, required RMP information is general enough that it is unlikely to provide a basis for reverse engineering a process. For example, a source must report in its RMP whether overpressurization is a hazard and whether relief valves are used to control pressure, but it is not required to report information on actual pressures used, flow rates, chemical composition, or the configuration of equipment. Moreover, while RMP information may provide some data that could be used in an attempt to discover CBI information through reverse engineering, it typically will not provide enough data for such an attempt to succeed, because the source is not required to provide a detailed description of the chemistry or production volume of the process. Businesses claiming CBI based on the threat of reverse engineering will be required to show how reverse engineering could in fact succeed with the information that the RMP would otherwise make public, together with other publicly available information. A business unable to do so will have its claim denied.

While EPA is requiring that a source claiming a chemical’s identity as CBI provide the generic category or class name of the chemical, the RMP does not require sources to provide information about the adverse health effects of the chemical. Chemicals were included in the section 112(r) program because they are acutely toxic or flammable; health effects related to chronic exposure were not considered because they are addressed by other rules (see List Rule at 59 FR 4481). EPA believes that generic names are sufficient to indicatethe general health concerns from shortterm exposures. Should a member of the public desire more information, EPA encourages the use of EPCRA section 322(h), which provides a means for the public to obtain information about the adverse health effects of a chemical covered by that statute, where the chemical’s identity has been claimed a trade secret. The public will find this provision of EPCRA useful because most sources subject to the RMP rule are also subject to EPCRA.

3. Up-front Substantiation of CBI Claims

One commenter supported the proposal to require CBI claims to be substantiated at the time they are made. Another commenter stated that there is no compelling need to require up-front substantiation. The commenter stated that up-front substantiation would place a sizable burden on both industry and EPA and would be in direct conflict with the Paperwork Reduction Act. The commenter claimed that, with the exception of EPCRA, where a submitter is allowed to claim only one data element—chemical identity—as CBI, it is EPA’s standard procedure not to require submitters to provide written substantiation unless a record has been requested. Further, the commenter stated that the Agency has not shown any reason for departing from that procedure in this rule.

EPA believes that requiring up-front substantiation of CBI claims made for RMP data has ample precedent, is fully consistent with the Agency’s CBI regulations and the Paperwork Reduction Act, and is critical to achieving the public information purposes of the accident prevention program. EPCRA is not the only example of an up-front substantiation requirement. The Agency has also required up-front substantiation in several other regulatory contexts, including those where, like here, providing the public with health and safety information is an important objective [see e.g., 40 CFR section 725.94, 40 CFR section 710.38, and 40 CFR section 720.85 (regulations promulgated under Toxic Substances Control Act)].

Even under its general CBI regulations, the Agency need not wait for a request to release data to require businesses to substantiate their CBI claims. When EPA expects to get a request to release data claimed confidential, the Agency is to initiate ‘‘at the earliest practicable time’’ the regulations’’ procedures for making CBI determinations (40 CFR section 2.204(a)(3)). Those procedures include calling on affected businesses to substantiate their claims (see 40 CFR section 2.204(e)). Since state and local agencies, environmental groups, academics and others have already indicated their interest in obtaining complete RMP data (see comments received on this rulemaking, available in the DOCKET), EPA fully expects to get requests for RMP data claimed CBI. Consequently, even if EPA did not establish an up-front substantiation requirement in this rule, under the Agency’s general CBI regulations it could require businesses claiming CBI for RMP data to substantiate their claims without first receiving a request torelease the data. Establishing an upfront requirement in this rule will simply allow EPA to obtain substantiation of CBI claims without having to request it in every instance.

Requiring up-front substantiation for RMP CBI claims is consistent with the Paperwork Reduction Act. Any burden posed by this requirement has already been evaluated as part of the Information Collection Request (ICR) associated with this rulemaking. EPA disagrees that up-front substantiation will impose a substantial or undue burden. As noted above, under EPA’s current CBI regulations, a source claiming CBI could and probably would be required to provide substantiation for its claim, in view of the public interest in RMP information. A requirement to submit substantiation with the claim should thus make little difference to the source. Moreover, a source presumably does not make any claim of CBI lightly. Before filing a CBI claim, the source must first determine whether the claim meets the criteria specified in 40 CFR section 2.208. Up-front substantiation only requires that the source document that determination at the time it files its claim. Since it would be sensible for a source to document the basis of its CBI claim for its own purposes (e.g., in the case of a request for substantiation), EPA expects that many sources already prepare documentation for their CBI claims by the time they file them. Also, submitting substantiation at the time of claim reduces any additional burden later, such as reviewing the Agency’s request, retrieving the relevant information, etc. Therefore, providing documentation at the time of filing should impose no additional burden.

In view of the public informationfunction of RMPs, EPA believes that upfront substantiation is clearly warranted

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for CBI claims made for RMP data. Upfront substantiation will ensure that sources filing claims have carefully considered whether the data they seek to protect in fact meets the criteria for protection. Given the public interest already expressed in RMP data, EPA expects that CBI claims for RMP data will have to be substantiated at some point. Up-front substantiation will save EPA and the public time and resources that would otherwise be required to respond to each CBI claim with a request for substantiation. EPA is therefore promulgating the up-front substantiation requirement as proposed.

4. State and Local Agency Access to Unredacted RMPs

One commenter objected to EPA’s statement in the proposal that it would provide unredacted (unsanitized) versions of the RMPs to a state and local agency only upon meeting the criteria required by the EPA’s CBI rules at 40
CFR Part 2. 4 The commenter, an association of fire fighters, argued that the Agency’s position was inconsistent with CAA section 112(r)(7)(B)(iii), which provides that RMPs ‘‘shall . . . be submitted to the Chemical Safety and Hazard Investigation Board [a federal agency], to the State in which the stationary source is located, and to any local agency or entity having responsibility for planning for or responding to accidental releases which may occur at such source . . . .’’ The commenter claimed that this provision entitles the specified entities, including local fire departments, to receive unredacted RMPs without having to make the showings required by EPA’s CBI regulations.

EPA is not resolving this issue today. The Agency has reviewed the relevant statutory text and legislative history, as well as analogous provisions of EPCRA, and believes that arguments can be made on both sides of this issue. While section 112(r)(7)(B)(iii) calls for RMPs to be submitted to states, local entities and the Board, it is not clear that Congress intended CBI contained in RMPs to be provided to those entities without ensuring appropriate protection of CBI.

4 Section 2.301(h)(3) provides that a State or local government may obtain CBI from EPA under two circumstances: (1) it provides EPA a written opinion from its chief legal officer or counsel stating that the State or local agency has the authority under applicable State or local law to compel the business to disclose the information directly; or (2) the businesses whose information is
disclosed are informed and the State or local government has shown to a EPA legal office’s
satisfaction that its disclosure of the information will be governed by State or local law and by ‘‘procedures which will provide adequate protection to the interests of affected businesses.’’ At stake in resolving this issue are two important interests—local responders’ interest in unrestricted access to information that may be critical to their safety and effectiveness in responding to emergencies and businesses’ interest in protecting sensitive information from their competitors. Before making a final decision on this issue, EPA believes it would benefit from further public input. Because EPA stated that it would not provide unredacted RMPs to states and local agencies, those interested in protecting CBI may not have considered it necessary to lay out the legal and policy arguments supporting their views. State and local agencies, many of which in the past have expressed concern about the potential administrative burden of receiving RMPs directly from sources, also did not comment on the issue. EPA has therefore decided to accept additional comments on this issue alone. (Additional comments on any other issues addressed in this rulemaking will not be considered or addressed, since the Agency is taking final action on them here.) Comments should be mailed to the persons listed in the preceding

FOR FURTHER INFORMATION CONTACT section. In the meantime, unredacted RMPs will be available to states, local agencies and the Board under the terms of the Agency’s existing CBI regulations at 40 CFR section 2.301(h)(3) (for state and local agencies) and 40 CFR section 2.209(c) (for the Board).

Section 112(r)(7)(B)(iii) states in relevant part:

[RMPs] shall also be submitted to the Chemical Safety and Hazard Investigation Board, to the State in which the stationary source is located, and to any local agency or entity having responsibility for planning for or responding to accidental releases which may occur at such source, and shall be available to the public under section 114(c) of [the Act]. Section 114(c) provides for the public availability of any information obtained by EPA under the Clean Air Act, except for information (other than emissions data) that would divulge trade secrets.

From a public policy perspective, there are some obvious advantages to reading section 112(r)(7)(B)(iii) in the way the commenter suggests. Local fire departments and other local responders are typically the first to arrive at the scene of chemical accidents in their jurisdictions. RMP information that first responders could find helpful include chemical identity, chemical quantity, and potential source of an accident. Under EPA’s regulations, however, any or all of this information could be claimed CBI. In addition, state and local authorities are often in the best position to assess the adequacy of a source’s risk management program and to initiate a dialogue with the facility should its RMP indicate a need for improvement. However, state and local authorities’ ability to provide this contribution to community safety would be impeded to the extent a source claimed key information as CBI. While states and local agencies may obtain information claimed CBI under EPA’s CBI regulations (assuming they can make the requisite showing), the time required to obtain the necessary authority or findings from state or local and EPA officials could be substantial.

At the same time, there are also public policy reasons for ensuring protection of CBI contained in RMPs. Congress has in many statutes, including the CAA and EPCRA, provided for the protection of trade secrets to safeguard the competitive position of private businesses. Businesses’ ability to maintain the confidentiality of trade secrets helps ensure competition in the
U.S. economy and U.S. businesses’ competitive position in the world economy. Protection of trade secrets also encourages innovation, which is an important contributor to economic growth.

A reading of section 112(r)(7)(B)(iii) that demands submission of unredacted RMPs to states, local entities, and the Board may lead to widespread public access to information claimed CBI. For purposes of section 112(r)(7)(B)(iii), ‘‘any local agency or entity having responsibility for planning for or responding to accidental releases’’ includes local emergency planning committees (LEPCs) established under EPCRA. Section 301(c) of EPCRA provides that LEPCs must include representatives from both the public and private sectors, including the media and facilities subject to EPCRA requirements. Submission of an unredacted RMP to an LEPC would thus entail release of CBI to some members of the public and potentially even competitors. 5 More generally, local agencies may not be subject to any legal requirement to protect CBI and may lack the knowledge and resources to address CBI claims. Arguably, it would be

5 EPA does not believe that submission of an RMP containing CBI to the statutorily specified entities would defeat a source’s ability to claim information as CBI for purposes of section 114(c) and EPA’s CBI regulations. Under those regulations, information that has been released to the public cannot be claimed CBI. Release of a RMP containing CBI to the entities specified by section 112(r)(7)(B)(iii), including LEPCs, would not constitute such a release. EPCRA similarly provides that disclosure of
trade secret information to an LEPC does not prevent a facility from claiming the information confidential (see EPCRA section 322(b)(1)).

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anomalous for Congress to require EPA to protect trade secrets contained in RMPs against release to the public only to risk divulging the same information by requiring submission of unredacted RMPs to a broad range of entities that may not have the need or capacity to protect CBI themselves. It would also appear inconsistent with the approach Congress took to protecting trade secrets in EPCRA, where Congress did not provide for release of trade secret chemical identity information to local agencies.

Relatedly, many state and local agencies objected to EPA’s original proposal in the RMP proposed rulemaking (58 FR 54190, October 20, 1993) that sources submit RMPs directly to States, local agencies, and the Board, as well as EPA. They noted that managing the information contained in RMPs would be difficult without a significant expenditure of typically scarce resources. Many states and local agencies thus supported EPA’s final decision to develop an electronic submission and distribution system that would allow covered sources to submit their RMPs to EPA, which would make them available to states, local agencies, and the Board, as well as the general public. If the statute is read to require submission of RMP information to state and local agencies, and the Board, to the extent it is claimed as CBI, the resource concerns raised by State and local agencies commenters likely would be raised to that extent again.

EPA also questions the extent to which states, local entities and the Board would be disadvantaged if they did not receive unredacted RMPs without making the showings required by EPA’s CBI regulations. As noted earlier, EPA expects that relatively little RMP information will be CBI. RMP datawill only rarely contain CBI, and the upfront substantiation will minimize the number of CBI claims it receives by ensuring that sources carefully examine the basis for any claims before submitting them. Consequently, the Agency believes that a state or local agency will rarely confront a redacted
RMP.

Moreover, EPCRA provides state and local entities, including fire departments, with access to much of the pertinent data already. EPA’s regulations under EPCRA cover a universe of sources and chemicals that includes most, if not all, the sources and substances covered by the RMP rule. The EPCRA regulations require reporting of some of the same information required by the RMP rule, including chemical identity. EPCRA withholds from public release only chemical identities that are trade secrets and the location of specific chemicals where a facility so requests. In practice, relatively few facilities have requested trade secret protection for a chemical’s identity.

Additionally, EPCRA section 312(f) empowers local fire departments to conduct on-site inspections at facilities subject to EPCRA section 312(a) and obtain information on chemical location. Most facilities subject to EPCRA section 312(a) are also subject to the RMP rule. On-site inspections could also provide information on hazards and mitigation measures. In addition, EPCRA section 303(d)(3) authorizes LEPCs, which include representatives of fire departments, to request from facilities covered by EPCRA section 302(b) such information as may be necessary to prepare an emergency response plan and to include such information in the plan as appropriate. Some sources subject to the RMP rule are also covered by EPCRA section 302(b).

In light of the points made above, EPA questions whether section 112(r)(7)(B)(iii) should be interpreted to require submission of unredacted RMPs containing CBI to the statutorily specified entities without provision being made for protecting CBI. EPA invites the public to provide any additional comment or information relevant to interpreting the submission requirement of section 112(r)(7)(B)(iii).

5. Other CBI Issues

Two commenters disagreed with EPA’s statement that a source cannot make a CBI claim for information available to the public under EPCRA or another statute. They claimed that a request for information under EPCRA cannot supersede the CBI provisions applicable to data collected under the authorities of the CAA or Toxic Substances Control Act or any other regulatory program.

EPA does not agree with this comment. Claims of CBI may not be upheld if the information is properly obtainable or made public under other statutes or authorities. For example, chemical quantity on site is available to the public under EPCRA Tier II reporting. In addition, under EPCRA section 303(d)(3), LEPCs have the authority to request any information they need to develop and implement community emergency response plans. If information obtained through such a request is included in the community plan, it will become available to the public under EPCRA section 324. Information obtainable or made public under EPCRA would not be eligible for CBI protection under 40 CFR section 2.208, which specifically excludes from CBI protection information already available to the public. Filing a CBI claim under the CAA or another statute does not protect information if it is legitimately requested and made public under other federal, state, or local law. Information obtainable or made public (through proper means) under existing statutes cannot be CBI under EPA’s CBI regulations.

6. Actions Taken

In summary, the Agency is adding two sections (68.151 and 68.152) to Part
68. Section 68.151 sets forth the procedures for a source to follow when asserting a CBI claim and lists data elements that can not be claimed as CBI. This section also requires sources filing CBI claims to provide the information claimed confidential, in a format to be specified by EPA, instead of the unsanitized paper copy of the RMP as discussed in the proposal. Section
68.152 sets forth the procedures for substantiating CBI claims. Sources claiming CBI are required to submit their substantiation of their claims at the same time they submit their RMPs.

E. Other Issues

Two commenters asked why EPA had proposed to drop the phrase ‘‘if used’’ in section 68.165(b)(3) where the rule asks for the basis of the offsite consequence analysis results. EPA has decided to retain the language, since sources will have a choice of using either EPA’s RMP guidance documents or a model. Where a model is used, the source will have to provide the name of the model. These commenters also asked why EPA proposed to drop (alternative releases only) from section 68.165(b)(13). EPA has also decided to retain the parenthetical language.

One commenter stated that EPA should allow sources to submit RMPs either electronically or in hard copy. The commenter stated that not allowing hard copy submissions will be burdensome on many sources who have never filed an electronic report to the government before. As stated in the April proposal, EPA is allowing sources to submit RMPs on paper. Paper submitters are asked to fill out a simple paper form to tell EPA why they are unable to file electronically.

Two commenters objected to placing offsite consequence analysis (OCA) data, particularly worst-case release scenarios, on the Internet, for security reasons. Issues related to public access to OCA data are beyond the scope of this rulemaking, as this action is limited to the issues discussed above. It does

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not include decisions regarding how the public will access the OCA data elements of the RMPs. Statements in the preamble about EPA providing public access to RMP data are not intended to address which portions of the RMP data will be electronically available.

A number of commenters were concerned about a statement EPA made in the preamble to the proposed rule regarding the definition of ‘‘process’’, and stated that EPA’s interpretation of ‘‘process’’ is not consistent with the interpretation the Occupational Safety and Health Administration (OSHA) uses in its process safety management (PSM) standard (29 CFR 1910.119). In this rulemaking, EPA did not propose any changes to the definition of process nor is it adopting any changes to the definition. As EPA stated in the preamble to the final RMP rule, it will interpret ‘‘process’’ consistently with OSHA’s interpretation of that term (29 CFR 1910.119). Therefore, if a source is subject to the PSM rule, the limits of its process(es) for purposes of OSHA PSM will be the limits of its process(es) for purposes of RMP (except in cases involving atmospheric storage tanks containing flammable regulated substances, which are exempt from PSM but not RMP). If a source is not covered by OSHA PSM and is complicated from an engineering perspective, it should consider contacting its implementing agency for advice on determining process boundaries. EPA and OSHA are coordinating the agencies’ approach to common issues, such as the interpretation of ‘‘process’’.

F. Technical Corrections

When Part 68 was promulgated, the text of section 68.79(a), was drawn from the OSHA PSM standard, but it was not revised to reflect the different structure of EPA’s rule. The OSHA PSM standard is contained in a single section; EPA’s Program 3 prevention program is contained in a subpart. Rather than referencing ‘‘this section,’’ the paragraph should have referenced the ‘‘subpart.’’ Therefore, as proposed, EPA is changing ‘‘section’’ to ‘‘subpart’’ in section 68.79(a).

Under section 68.180(b), EPA intended that all covered sources report the name and telephone number of the agency with which they coordinate emergency response activities, even if the source is not required to have an emergency response plan. However, the rule refers only to coordinating the emergency plan. In this action, EPA is revising this section to refer to the local agency with which emergency response activities and the emergency response plan is coordinated. IV. Section-by-Section Discussion of the Final Rule

In Section 68.3, Definitions, the definition of SIC is removed and replaced by the definition of NAICS.

Section 68.10, Applicability, is revised to replace the SIC codes with NAICS codes, as discussed above.

Section 68.42, Five-Year Accident History, is revised to require the percentage concentration by weight of regulated toxic substances released in a liquid mixture and the five- or six-digit NAICS code that most closely corresponds to the process that had the release. The phrase ‘‘five- or six-digit’’ has been added before the NAICS code to clarify the level of detail required for NAICS code reporting.

Section 68.79, Compliance Audits, the word ‘‘section’’ in paragraph (a) is replaced by ‘‘subpart.’’

Section 68.150, Submission, is revised by adding a paragraph to state that procedures for asserting CBI claims and determining the sufficiency of such claims are provided in new Sections
68.151 and 68.152.

Section 68.151 is added to set forth the procedures to assert a CBI claim and list data elements that may not be claimed as CBI, as discussed above.

Section 68.152 is added to set forth procedures for substantiating CBI claims, as proposed.

Section 68.160, Registration, is revised by adding the requirements to report the method and description of latitude and longitude, replacing SIC codes with five- or six-digit NAICS codes, and adding the requirement to report Title V permit number, when applicable. This section is also revised to include optional data elements. The phrase ‘‘five- or six-digit’’ has been added before NAICS code to clarify the level of detail required for NAICS code reporting.

Section 68.165, Offsite Consequence Analysis, is revised by adding the requirement that the percentage weight of a regulated toxic substance in a liquid mixture be reported.

Section 68.170, Prevention Program/ Program 2, is revised to replace SIC codes with five- or six-digit NAICS codes, as is Section 68.175.

Section 68.180, Emergency Response Program, is revised to clarify that paragraph (b) covers both the coordination of response activities and plans, as proposed.

V. Judicial Review

The proposed rule amending the accidental release prevention requirements; under section 112(r)(7) was proposed in the Federal Register on April 17, 1998. This Federal Register action announces EPA’s final decision on the amendments. Under section 307(b)(1) of the CAA, judicial review of this action is available only by filing a petition for review in the U.S. Court of Appeals for the District of Columbia Circuit on or before March 8, 1999. Under section 307(b)(2) of the CAA, the requirements that are the subject of today’s action may not be challenged later in civil or criminal proceedings brought by EPA to enforce these requirements.

VI. Administrative Requirements

A. Docket

The docket is an organized and complete file of all the information considered by the EPA in the development of this rulemaking. The docket is a dynamic file, because it allows members of the public and industries involved to readily identify and locate documents so that they can effectively participate in the rulemaking process. Along with the proposed and promulgated rules and their preambles, the contents of the docket serve as the record in the case of judicial review. (See section 307(d)(7)(A) of the CAA.)

The official record for this rulemaking, as well as the public version, has been established for this rulemaking under Docket No. A–98–08 (including comments and data submitted electronically). A public version of this record, including printed, paper versions of electronic comments, which does not include any information claimed as CBI, is available for inspection from 8:00 a.m. to 5:30 p.m., Monday through Friday, excluding legal holidays. The official rulemaking record is located at the address in

ADDRESSES at the beginning of this document.

B. Executive Order 12866

Under Executive Order (E.O.) 12866, [58 FR 51,735 (October 4, 1993)], the Agency must determine whether the regulatory action is ‘‘significant’’, and therefore subject to OMB review and the requirements of the E.O. The Order defines ‘‘significant regulatory action’’ as one that is likely to result in a rule that may:

(1) Have an annual effect on the economy of $100 million or more or adversely affect in a material way the economy, a sector of the economy, productivity, competition, jobs, the environment, public health or safety, or state, local or tribal government or communities;

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(2) Create a serious inconsistency or otherwise interfere with an action taken or planned by another agency;

(3) Materially alter the budgetary impact of entitlements, grants, user fees, or loan programs or the rights and obligations of recipients thereof; or

(4) Raise novel legal or policy issues arising out of legal mandates, the President’s priorities, or the principles set forth in the E.O.

Pursuant to the terms of Executive Order 12866, OMB has notified EPA that it considers this a ‘‘significant regulatory action’’ within the meaning of the Executive Order. EPA has submitted this action to OMB for review. Changes made in response to OMB suggestions or recommendations will be documented in the public record.

C. Executive Order 12875

Under Executive Order 12875, EPA may not issue a regulation that is not required by statute and that creates a mandate upon a State, local or tribal government, unless the Federal government provides the funds necessary to pay the direct compliance costs incurred by those governments, or EPA consults with those governments. If EPA complies by consulting, Executive Order 12875 requires EPA to provide to the Office of Management and Budget a description of the extent of EPA’s prior consultation with representatives of affected State, local and tribal governments, the nature of their concerns, copies of any written communications from the governments, and a statement supporting the need to issue the regulation. In addition, Executive Order 12875 requires EPA to develop an effective process permitting elected officials and other representatives of State, local and tribal governments ‘‘to provide meaningful and timely input to the development of regulatory proposals containing significant unfunded mandates.’’

EPA has concluded that this rule may create a nominal mandate on State, local or tribal governments and that the Federal government will not provide the funds necessary to pay the direct costs incurred by these governments in complying with the mandate. Specifically, some public entities may be covered sources and will have to add the new data elements to their RMP. In developing this rule, EPA consulted with state, local and tribal governments to enable them to provide meaningful and timely input in the development of this rule. Even though this rule revises Part 68 in a way that does not significantly change the burden imposed by the underlying rule, EPA has taken efforts to involve state and local entities in this regulatory effort. Specifically, much of the rule responds to issues raised by the Electronic Submission Workgroup discussed above, which includes State and local government stakeholders. In addition, EPA has recently conducted seminars with tribal governments; however, there were no concerns raised on any issues that are covered in this rule. EPA discussed the need for issuing this regulation in sections II and III in this preamble. Also, EPA provided OMB with copies of the comments to the proposed rule.

D. Executive Order 13045

Executive Order 13045: ‘‘Protection of Children from Environmental Health Risks and Safety Risks’’ (62 FR 19885, April 23, 1997) applies to any rule that: (1) is determined to be ‘‘economically significant’’ as defined under E.O. 12866, and (2) concerns an environmental health or safety risk that EPA has reason to believe may have a disproportionate effect on children. If the regulatory action meets both criteria, the Agency must evaluate the environmental health or safety effects of the planned rule on children, and explain why the planned regulation is preferable to other potentially effective and reasonably feasible alternatives considered by the Agency.

This final rule is not subject to the
E.O. 13045 because it is not ‘‘economically significant’’ as defined in
E.O. 12866, and because it does not involve decisions based on environmental health or safety risks.

E. Executive Order 13084

Under Executive Order 13084, EPA may not issue a regulation that is not required by statute, that significantly or uniquely affects the communities of Indian tribal governments, and that imposes substantial direct compliance costs on those communities, unless the Federal government provides the funds necessary to pay the direct compliance costs incurred by the tribal governments, or EPA consults with those governments. If EPA complies by consulting, Executive Order 13084 requires EPA to provide to the Office of Management and Budget, in a separately identified section of the preamble to the rule, a description of the extent of EPA’s prior consultation with representatives of affected tribal governments, a summary of the nature of their concerns, and a statement supporting the need to issue the regulation. In addition, Executive Order 13084 requires EPA to develop an effective process permitting elected and other representatives of Indian tribal governments ‘‘to provide meaningful and timely input in the development of regulatory policies on matters that significantly or uniquely affect their communities.’’

Today’s rule does not significantly or uniquely affect the communities of Indian tribal governments. Two of the amendments made by this rule, the addition of RMP data elements and the conversion of SIC codes to NAICS codes, impose only minimal burden on any sources that may be owned or operated by tribal governments, such as drinking water and waste water treatment systems. The third amendment made by this rule addresses the procedures for submission of confidential business information in the RMP. The sources that are mentioned above handle chemicals that are known to public (e.g., chlorine for use of disinfection, propane used for fuel, etc.). EPA does not, therefore, expect RMP information on these types of processes to include CBI, so any costs related to CBI will not fall on Indian tribal governments. Accordingly, the requirements of section 3(b) of Executive Order 13084 do not apply to this rule.

Notwithstanding the non-applicability of E. O. 13084, EPA has recently conducted seminars with the tribal governments. However, there were no concerns raised on any issues that are covered in this rule.

F. Regulatory Flexibility

EPA has determined that it is not necessary to prepare a regulatory flexibility analysis in connection with this final rule. EPA has also determined that this action will not have a significant economic impact on a substantial number of small entities. Two of the amendments made by this rule, the addition of RMP data elements and the conversion of SIC codes to NAICS codes, impose only minimal burden on small entities. Moreover, those small businesses that claim CBI when submitting the RMP will not face any costs beyond those imposed by the existing CBI regulations. Even considering the costs of CBI substantiation, however, there is no significant economic impact on a substantial number of small entities. EPA estimates that very few small entities (approximately 500) will claim CBI and that these few entities represent a small fraction of the small entities (less than 5 percent) affected by the RMP rule. Finally, EPA estimates that those small businesses filing CBI will experience a cost which is significantly less than one percent of their annual sales. For a more detailed analysis of the

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small entity impacts of CBI submission, see Document Number, IV-B–02, available in the docket for this rulemaking (see ADDRESSES section).

G. Paperwork Reduction

1. General

The information collection requirements in this rule have been submitted for approval to the Office of Management and Budget (OMB) under the Paperwork Reduction Act, 44 U.S.C.
3501 et seq. An Information Collection Request (ICR) document has been prepared by EPA (ICR No. 1656.05) and a copy may be obtained from Sandy Farmer, by mail at Office of Policy, Regulatory Information Division, U.S. Environmental Protection Agency (2137), 401 M St, SW, Washington, DC 20460, by e-mail at farmer.sandy@epamail.epa.gov or by calling (202) 260–2740. A copy may also be downloaded off the Internet at http:/ /www.epa.gov/icr. The information requirements are not effective until OMB approves them.

The submission of the RMP is mandated by section 112(r)(7) of the CAA and demonstrates compliance with Part 68 consistent with section 114(c) of the CAA. The information collected also will be made available to state and local governments and the public to enhance their preparedness, response, and prevention activities. Certain information in the RMP may be claimed as confidential business information under 40 CFR Part 2 and Part 68.

This rule will impose very little burden on affected sources. First, EPA estimates that the new data elements will require only a nominal burden, .25 hours for a typical source, because latitude and longitude method and description will be selected from a list of options, the Title V permit number is available to any source to which Title V applies, and the percentage weight of a toxic substance in a liquid mixture is usually provided by the supplier of the mixture. Second, the NAICS code provision is simply a change from one code to another. 6 Third, as discussed above in the preamble, EPA believes that the CBI provisions of this rule will add no additional burden beyond what sources otherwise would face in

6 EPA intends to provide several outreach mechanisms to assist sources in identifying their new NAICS code. RMP*Submit will provide a ‘‘pick list’’ that will make it easier for sources to find the appropriate code. Also, selected NAICS codes are included in the General Guidance for Risk Management Programs (July 1998) and in the industry-specific guidance documents that EPA is developing. EPA will also utilize the Emergency Planning and Community Right-to-Know Hotline at 800–424–9346 (or 703–412–9810) to assist sources in determining the source’s NAICS codes. complying with the CBI rules in 40 CFR Part 2. The Agency has calculated the burden of substantiations made for purposes of this rule below.

Burden means the total time, effort, or financial resources expended by persons to generate, maintain, retain, or disclose or provide information to or for a Federal agency. This includes the time needed to review instructions; develop, acquire, install, and utilize technology and system for the purposes of collecting, validating, and verifying information, processing and maintaining information, and disclosing and providing information; adjust the existing ways to comply with any previously applicable instructions and requirements; train personnel to be able to respond to a collection of information; search data sources; complete and review the collection of information; and transmit or otherwise disclose the information.

An agency may not conduct or sponsor, and a person is not required to respond to a collection of information unless it displays a currently valid OMB control number. The OMB control numbers for EPA’s regulations are listed in 40 CFR Part 9 and 48 CFR Chapter
15.

2. CBI Burden

In the Notice of Proposed Rulemaking for these amendments, EPA proposed to amend existing 40 CFR Part 68 to add two sections which would clarify the procedures for submitting RMPs that contain confidential business information (CBI). As proposed, CBI would be handled in much the same way as it presently is under other EPA programs, except that EPA would require sources claiming CBI to submit documentation substantiating their CBI claims at the time such claims were made and EPA also would not permit CBI claims for certain data elements which clearly are not CBI. Aside from these procedural changes, however, the proposed rule was substantively identical to the existing rules governing the substantiation of CBI claims, presently codified in 40 CFR Part 2.

At the time it proposed these amendments, EPA estimated the public reporting burden for CBI claims to be 15 hours for chemical manufacturers with Program 3 processes, the only kinds of facilities that EPA expects to be able to claim CBI for any RMP data elements. This estimate was premised upon EPA’s assessment that it would require 8.5 hours per claim to develop and submit the CBI substantiation and 6.5 hours to complete an unsanitized version of the RMP, for a total of 15 hours. EPA also estimated that approximately 20 percent of the 4000 chemical manufacturers (out of 64,200 stationary sources estimated to be covered by the RMP rule) may file CBI claims (800 sources). The 800 sources represent a conservative projection based on the Agency’s experience under EPCRA program. Consequently, the total annual public reporting burden for filing CBI claims was estimated to be approximately 12,000 hours over three years (800 facilities multiplied by an average burden of 15 hours), or an annual burden of 4,000 hours (Information Collection Request No. 1656.04).

a. Comment received. EPA received one comment on the ICR developed for the proposed rule, opposing up-front substantiation of any CBI claims. The commenter stated that ‘‘[t]his is a major departure from standard EPA procedure, and would impose a substantial and unjustified burden for several years.’’The commenter further added that upfront substantiation would significantly increase the burden of this rule, and that up-front substantiation unnecessarily increases the volume and potential loss of CBI documents. The commenter also stated that the estimate of 15 hours for chemical manufacturers ‘‘seems unreasonably low,’’ and cited the EPA burden estimate of 27.7 to 33.2 hours per claim (with an average of 28.8) under the trade secret provisions of
EPCRA.

In the preamble to the proposed rule, EPA estimated that 20 percent of the 4,000 chemical manufacturers will file a CBI claim. The commenter contends that ‘‘[t]he EPA analysis * * * excludes facilities in other industries that will need to file CBI claims.’’

Finally, the commenter stated that claiming multiple data elements as CBI will increase reporting burden.

b. EPA response. Burden Estimates: EPA disagrees with these comments. As pointed out above, the requirement to submit up-front substantiation of CBI claims imposes no additional burden. In addition, the total burden of the CBI provisions of this rule are not understated. EPA has re-examined its analysis in light of the commenter’s concerns and has determined—contrary to the commenter’s claim—that its initial estimate of the total burden associated with preparing and claiming CBI was likely too conservative. As explained below, the Agency’s best available information indicates that the process of documenting and submitting a claim of CBI should impose a burden of approximately 9.5 hours per CBI claimant.

First, EPA believes that the requirement to submit, at the time a source claims information as CBI,

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substantiation demonstrating that the material truly is CBI imposes no burden on sources beyond that which presently exists under EPA’s CBI regulations in Part 2. In order to decide whether they might properly claim CBI for a given piece of information, a source must determine if the criteria stated in section
2.208 of 40 CFR Part 2 are satisfied. Naturally, a source goes through this process before a CBI claim is made. EPA agrees that most programs do not require the information that forms the basis for the substantiation to be submitted at the time of the claim; however, a facility must still determine whether or not a claim can be substantiated. Because existing rules require sources to formulate a legitimate basis for claiming CBI, even if those rules do not require immediate documentation, and because the Agency fully expects requests for RMP information which will necessitate sources’ submitting suchdocumentation, EPA believes that upfront submission will not increase the burden of the regulation.

Second, in response to the commenter’s claim that the Agency had underestimated the total burden associated with CBI claims, EPA undertook a review of recent information collection requests (ICRs) covering data similar to that required to be submitted in an RMP. Initially, EPA examined the ICR prepared for Part 2 itself (ICR No. 1665.02, OMB Control No. 2020–0003). Under an analysis contained in the Statement of Support for the ICR, the Agency estimated that it takes approximately 9.4 hours to substantiate claims of CBI, prepare documentation, and submit such documentation to EPA. Next, the Agency reviewed a survey conducted by the Agency (under Office of Management and Budget clearance

# 2070–0034), to present the average burden associated with indicating confidential business information claims for certain data elements under the proposed inventory update rule (IUR) amendment under TSCA section
8. This survey specifically asked affected industry how long it would take to prepare CBI claims for two data elements—chemical identity and production volume range information. Part 68 also requires similar information (e.g., chemical identity and maximum quantity in a process) to be included in a source’s RMP and, indeed, EPA anticipates that they will be the data elements most likely to be claimed CBI. The average burden estimates for chemical identity were between 1.82 and 3.13 hours, and the average burden estimates for production volume in ranges were between 0.87 and 2.08 hours. Thus, assuming that the average source claims both chemical identity and the maximum quantity in a process as CBI, a conservative estimate for the reporting burden would be 5.21 hours. Finally, EPA examined the burden estimate upon which it relied at proposal. That estimate predicted that the average CBI claim would take 15 hours, of which 8.5 would be developing and submitting the CBI claim, and 6.5 would be completing an unsanitized version of the RMP. In view of EPA’s current plan not to require a source claiming CBI to submit a full, unsanitized RMP, but instead to submit only the particular elements claimed as CBI, the Agency expects the latter burden to decrease to 1 hour, for a total burden of 9.5 hours.

In light of its extensive research of the burden hours involved in preparing and submitting CBI claims, EPA believes that the total burden estimate was not understated in the April proposal. Rather, other ICRs and the ICR proposal, combined with the changes to the method of documenting CBI claims, indicate that a burden estimate between
5.21 and 9.5 hours is appropriate for this final rule. EPA has selected the most conservative of these, 9.5 hours, in its ICR for this final rule.

EPA rejected one ICR’s burden estimate as being inapplicable to the present rulemaking. Although the commenter urged the Agency to adopt the estimate associated with trade secret claims under EPCRA (28 hours), EPA believes that the estimates discussed above are more accurate for several reasons. First, the EPCRA figures are based upon a survey with a very small sample size, as compared to the TSCA survey cited previously. Second, most (if not all) of the facilities submitting RMPs are likely to already be reporting under sections 311 and 312 or section 313 of EPCRA, and many of the manufacturers submitting an RMP are subject to TSCA reporting requirements; thus, most sources likely to claim CBI for an RMP data element will have already done some analysis of whether or not such information would reveal legitimately confidential matter.

Other Facilities Can Claim CBI: The Agency does not agree with the commenter’s claim that facilities other than chemical manufacturers might be expected to claim CBI for information contained in their RMPs. The other industries affected by the RMP rule (e.g., propane retailers, publicly owned treatment works) will not be disclosing in the RMP information that is likely to cause substantial harm to the business’s competitive position. For example, covered public drinking water and wastewater treatment plants generally use common regulated substances in standard processes (i.e., chlorine used for disinfection). Also, covered processes at many sources involve the storage of regulated substances that the sources sell (e.g., propane, ammonia), so the processes are already public knowledge. Other covered processes involve the use of well-known combinations of regulated substances such as refrigerants. Therefore, it is not likely that these businesses would claim information as CBI.

As a point of comparison, EPA notes that of the 869,000 facilities that are estimated to be required to report under sections 311 and 312 of EPCRA, approximately 58 facilities have submitted trade secret claims for under those sections. For this reason, EPA believes the estimate of 800 sources may, in fact, be an overestimate of the number of sources claiming CBI.

Reporting Multiple Data Elements: The Agency disagrees with the commenters assertion that it has underestimated the reporting burden on sources’ claiming multiple data elements as CBI. The burden figures stated above are based on the Agency’s estimates of the average number of data elements that a typical source will likely claim CBI.

Public reporting of the new RMP data elements is estimated to require an average of .25 hours for all sources (64,200 sources) and substantiating CBI claims is estimated to take approximately 9.5 hours for certain chemical manufacturing sources (800 sources). The aggregate increase in burden over that estimated in the previous Information Collection Request (ICR) for part 68 is estimated to be about 23,650 hours over three years, or an annual burden of 7,883 hours for the three years covered by the ICR.

H. Unfunded Mandates Reform Act

Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), P.L. 104– 4, establishes requirements for Federal agencies to assess the effects of their regulatory actions on State, local, and tribal governments and the private sector. Under section 202 of the UMRA, EPA generally must prepare a written statement, including a cost-benefit analysis, for proposed and final rules with ‘‘Federal mandates’’ that may result in expenditures to State, local, and tribal governments, in the aggregate, or to the private sector, of $100 million or more in any one year. Before promulgating an EPA rule for which a written statement is needed, section 205

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of the UMRA generally requires EPA to identify and consider a reasonable number of regulatory alternatives andadopt the least costly, most costeffective or least burdensome alternative that achieves the objectives of the rule. The provisions of section 205 do not apply when they are inconsistent with applicable law. Moreover, section 205 allows EPA to adopt an alternative other than the least costly, most cost-effective or least burdensome alternative if the Administrator publishes with the final rule an explanation why that alternative was not adopted. Before EPA establishes any regulatory requirements that may significantly or uniquely affect small governments, including tribal governments, it must have developed under section 203 of the UMRA a small government agency plan. The plan must provide for notifying potentially affected small governments, enabling officials of affected small governments to have meaningful and timely input in the development of EPA regulatory proposals with significant Federal intergovernmental mandates, and informing, educating, and advising small governments on compliance with the regulatory requirements.

EPA has determined that this rule does not contain a Federal mandate that may result in expenditures of $100 million or more for state, local, and tribal governments, in the aggregate, or the private sector in any one year. The EPA has determined that the total nationwide capital cost for these rule amendments is zero and the annual nationwide cost for these amendments is less than $1 million. Thus, today’s rule is not subject to the requirements of sections 202 and 205 of the Unfunded Mandates Act.

EPA has determined that this rule contains no regulatory requirements that might significantly or uniquely affect small governments. Small governments are unlikely to claim information confidential, because sources owned or operated by these entities (e.g., drinking water and waste water treatment systems), handle chemicals that are known to public. The new data elements and the conversion of SIC codes to NAICS codes impose only minimal burden on these entities.

I. National Technology Transfer and Advancement Act

Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (‘‘NTTAA’’), Pub L. 104– 113, section 12(d)(15 U.S.C. 272 note), directs EPA to use voluntary consensus standards in its regulatory activities unless to do so would be inconsistent with applicable law or otherwise impractical. Voluntary consensus standards are technical standards (e.g., materials specifications, test methods, sampling procedures, business practices) that are developed or adopted by voluntary consensus standards bodies. The NTTAA requires EPA to provide Congress, through OMB, explanations when the Agency decides not to use available and applicable voluntary consensus standards.

This action does not involve technical standards. Therefore, EPA did not consider the use of any voluntary consensus standards.

J. Congressional Review Act

The Congressional Review Act, 5
U.S.C. section 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States. EPA will submit a report containing this rule and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register . This action is not a ‘‘major rule’’ as defined by 5 U.S.C. section 804(2). This rule will be effective February 5, 1999.

A PPENDIX TO P REAMBLE —D ATA E LEMENTS T HAT M AY N OT BE C LAIMED AS CBI

Rule element

68.160(b)(1) Stationary source name, street,

city, county, state, zip code, latitude, and longitude, method for obtaining latitude and longitude, and description of location that latitude and longitude represent

.68.160(b)(2) Stationary source Dun and Bradstreet number. 68.160(b)(3) Name and Dun and Bradstreet

number of the corporate parent company. 68.160(b)(4) The name, telephone number, and

mailing address of the owner/operator. 68.160(b)(5) The name and title of the person

or position with overall responsibility for RMP elements and implementation

. 68.160(b)(6) The name, title, telephone number,

and 24-hour telephone number of the emergency contact

. 68.160(b)(7) Program level and NAICS code of

the process

.68.160(b)(8) The stationary source EPA identifier

. 68.160(b)(10) Whether the stationary source is

subject to 29 CFR 1910.119

. 68.160(b)(11) Whether the stationary source is

subject to 40 CFR Part 355

.

68.160(b)(12) If the stationary source has a

CAA Title V operating permit, the permit number

. Comment

This information is filed with EPA and other agencies under other regulations and is made

available to the public and, therefore, does not meet the criteria for CBI claims. It is also
available in business and other directories.

This information provides no information that would affect a source’s competitive position.

This information is filed with state and local agencies under EPCRA and is made available to

the public and, therefore, does not meet the criteria for CBI claims.

This information provides no information that would affect a source’s competitive position.

This information provides no information that would affect a source’s competitive position.

This information provides no information that would affect a source’s competitive position.

Sources are required to notify the state and local agencies if they are subject to this rule; this

information is available to the public and, therefore, does not meet the criteria for CBI
claims. This information will be known to state and federal air agencies and is available to the public

and, therefore, does not meet the criteria for CBI claims.

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A PPENDIX TO P REAMBLE —D ATA E LEMENTS T HAT M AY N OT BE C LAIMED AS CBI—Continued

Rule element

68.160(b)(13) The date of the last safety inspection and the identity of the inspecting entity

. 68.165(b)(4) Basis of the results (give model

name if used)

.68.165(b)(9) Wind speed and atmospheric stability class (toxics only)

. 68.165(b)(10) Topography (toxics only)

............. 68.165(b)(11) Distance to an endpoint

...............

68.165(b)(12) Public and environmental receptors within the distance

. 68.168 Five-year accident history

.......................

68.170(b), (d), (e)(1), and (f)–(k) 68.175(b), (d), (e)(1), and (f)–(p)NAICS code, prevention program compliance dates and information

. 68.180 Emergency response program

............... Comment

This information provides no information that would affect a source’s competitive position.

Without the chemical name and quantity, this reveals no business information.

This information provides no information that would affect a source’s competitive position.

Without the chemical name and quantity, this reveals no business information.By itself, this information provides no confidential information. Other elements that would reveal chemical identity or quantity may be claimed as CBI.By itself, this information provides no confidential information. Other elements that would reveal chemical identity or quantity may be claimed as CBI. Sources are required to report most of these releases and information (chemical released,

quantity, impacts) to the federal, state, and local agencies under CERCLA and EPCRA; these data are available to the public and, therefore, do not meet the criteria for CBI claims. Much of this information is also available from the public media.

NAICS codes and the prevention program compliance dates and information provide no information that would affect a source’s competitive position. This information provides no information that would affect a source’s competitive position.

List of Subjects in 40 CFR Part 68

Environmental protection, Administrative practice and procedure, Air pollution control, Chemicals, Hazardous substances, Intergovernmental relations, Reporting and recordkeeping requirements.

Dated: December 29, 1998.
Carol M. Browner,

Administrator.

For the reasons set out in the preamble, title 40, chapter I, subchapter C, part 68 of the Code of Federal Regulations is amended to read as follows:

PART 68—CHEMICAL ACCIDENT PREVENTION PROVISIONS

1. The authority citation for Part 68 continues to read as follows:

Authority: 42 U.S.C. 7412(r), 7601(a)(1),
7661–7661f.

2. Section 68.3 is amended by removing the definition of SIC and by adding in alphabetical order the definition for NAICS to read as follows:

§ 68.3 Definitions.

* * * * *

NAICS means North American Industry Classification System.

* * * * *

3. Section 68.10 is amended by revising paragraph (d)(1) to read as follows:

§ 68.10 Applicability.

* * * * *

(d) * * * (1) The process is in NAICS code 32211, 32411, 32511, 325181, 325188, 325192, 325199, 325211, 325311, or 32532; or

* * * * *

4. Section 68.42 is amended by revising paragraph (b)(3), redesignating paragraphs (b)(4) through (b)(10) as paragraphs (b)(5) through (b)(11) and by adding a new paragraph (b)(4) to read as follows:

§ 68.42 Five-year accident history.

* * * * *

(b) * * * (3) Estimated quantity released in pounds and, for mixtures containing regulated toxic substances, percentage concentration by weight of the released regulated toxic substance in the liquid mixture;

(4) Five- or six-digit NAICS code that most closely corresponds to the process;

* * * * *

5. Section 68.79 is amended by revising paragraph (a) to read as follows:

§ . 68.79 Compliance audits.

(a) The owner or operator shall certify that they have evaluated compliance with the provisions of this subpart at least every three years to verify that procedures and practices developed under this subpart are adequate and are being followed.

* * * * *

6. Section 68.150 is amended by adding paragraph (e) to read as follows:

§ 68.150 Submission.

* * * * *

(e) Procedures for asserting that information submitted in the RMP is entitled to protection as confidential business information are set forth in §§ 68.151 and 68.152. 7. Section 68.151 is added to read as follows:

§ 68.151 Assertion of claims of
confidential business information.

(a) Except as provided in paragraph (b) of this section, an owner or operator of a stationary source required to report or otherwise provide information under this part may make a claim of confidential business information for any such information that meets the criteria set forth in 40 CFR 2.301.

(b) Notwithstanding the provisions of 40 CFR part 2, an owner or operator of a stationary source subject to this part may not claim as confidential business information the following information:

(1) Registration data required by § 68.160(b)(1) through (b)(6) and (b)(8), (b)(10) through (b)(13) and NAICS code and Program level of the process set forth in § 68.160(b)(7);

(2) Offsite consequence analysis data required by § 68.165(b)(4), (b)(9), (b)(10), (b)(11), and (b)(12).

(3) Accident history data required by § 68.168;

(4) Prevention program data required by § 68.170(b), (d), (e)(1), (f) through (k);

(5) Prevention program data required by § 68.175(b), (d), (e)(1), (f) through (p); and

(6) Emergency response program data required by § 68.180.

(c) Notwithstanding the procedures specified in 40 CFR part 2, an owner or operator asserting a claim of CBI with respect to information contained in its RMP, shall submit to EPA at the time it submits the RMP the following:

(1) The information claimed confidential, provided in a format to be specified by EPA;

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(2) A sanitized (redacted) copy of the RMP, with the notation ‘‘CBI’’ substituted for the information claimed confidential, except that a generic category or class name shall be substituted for any chemical name or identity claimed confidential; and

(3) The document or documents substantiating each claim of confidential business information, as described in § 68.152.

8. Section 68.152 is added to read as follows:

§ 68.152 Substantiating claims of
confidential business information.

(a) An owner or operator claiming that information is confidential business information must substantiate that claim by providing documentation that demonstrates that the claim meets the substantive criteria set forth in 40 CFR
2.301.

(b) Information that is submitted as part of the substantiation may be claimed confidential by marking it as confidential business information. Information not so marked will be treated as public and may be disclosed without notice to the submitter. If information that is submitted as part of the substantiation is claimed confidential, the owner or operator must provide a sanitized and unsanitized version of the substantiation.

(c) The owner, operator, or senior official with management responsibility of the stationary source shall sign a certification that the signer has personally examined the information submitted and that based on inquiry of the persons who compiled the information, the information is true, accurate, and complete, and that those portions of the substantiation claimed as confidential business information would, if disclosed, reveal trade secrets or other confidential business information.

9. Section 68.160 is amended by revising paragraphs (b)(1), (b)(7), and (b)(12) and adding paragraphs (b)(14) through (b)(18) to read as follows:

§ 68.160 Registration.

* * * * *

(b) * * * (1) Stationary source name, street, city, county, state, zip code, latitude and longitude, method for obtaining latitude and longitude, and description of location that latitude and longitude represent;

* * * * *

(7) For each covered process, the name and CAS number of each regulated substance held above the threshold quantity in the process, the maximum quantity of each regulated substance or mixture in the process (in pounds) to two significant digits, the five- or six-digit NAICS code that most closely corresponds to the process, and the Program level of the process;

* * * * *

(12) If the stationary source has a CAA Title V operating permit, the permit number; and

* * * * *

(14) Source or Parent Company E-Mail Address (Optional);

(15) Source Homepage address (Optional)

(16) Phone number at the source for public inquiries (Optional);

(17) Local Emergency Planning Committee (Optional);

(18) OSHA Voluntary Protection Program status (Optional); 10. Section 68.165 is amended by revising paragraph (b) to read as follows:

§ 68.165 Offsite consequence analysis.

* * * * *

(b) The owner or operator shall submit the following data:

(1) Chemical name; (2) Percentage weight of the chemical in a liquid mixture (toxics only);

(3) Physical state (toxics only); (4) Basis of results (give model name if used); (5) Scenario (explosion, fire, toxic gas release, or liquid spill and evaporation);

(6) Quantity released in pounds; (7) Release rate; (8) Release duration; (9) Wind speed and atmospheric stability class (toxics only);

(10) Topography (toxics only); (11) Distance to endpoint; (12) Public and environmental receptors within the distance;

(13) Passive mitigation considered; and

(14) Active mitigation considered (alternative releases only);

11. Section 68.170 is amended by revising paragraph (b) to read as follows:

§ 68.170 Prevention program/Program 2.

* * * * *

(b) The five- or six-digit NAICS code that most closely corresponds to the

process.
* * * * *

12. Section 68.175 is amended by revising paragraph (b) to read as follows:

§ 68.175 Prevention program/Program 3.

* * * * *

(b) The five- or six-digit NAICS code that most closely corresponds to the

process.
* * * * *

13. Section 68.180 is amended by revising paragraph (b) to read as follows:

§ 68.180 Emergency response program.

* * * * *

(b) The owner or operator shall provide the name and telephone number of the local agency with which emergency response activities and the emergency response plan is coordinated.

* * * * *
[FR Doc. 99–231 Filed 1–5–99; 8:45 am]

BILLING CODE 6560–50–P