United States
           Environmental Protection
           Agency
Office of Solid Waste
and Emergency Response
(5104)
EPA 550-B-99-009
April 1999
www.epa.gov/ceppo/
           RISK MANAGEMENT
           PROGRAM GUIDANCE
           FOR  OFFSITE
           CONSEQUENCE
           ANALYSIS
Chemical Emergency Preparedness and Prevention Office
            Pnnied on recycled paper

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This 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 substances regulated
under section 112(r) of the Clean Air Act. This document does not substitute for EPA's regulations, nor is it
a regulation itself.  Thus, it cannot impose legally binding requirements on EPA, States, or the regulated
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.

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                                    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	
        1.2     This Guidance Compared to Other Models
        1.3     Number of Scenarios to Analyze	
        1.4     Modeling Issues 	
        1.5     Steps for Performing the Analysis	
                1.5.1   Worst-Case Analysis for Toxic Gases	
                1.5.2   Worst-Case Analysis for Toxic Liquids	
                1.5.3   Worst-Case Analysis for Flammable Substances  	
                1.5.4   Alternative Scenario Analysis for Toxic Gases	
                1.5.5   Alternative Scenario Analysis for Toxic Liquids	
                1.5.6   Alternative Scenario Analysis for Flammable Substances
        1.6     Additional Sources of Information	  1-10

2       Determining Worst-Case Scenario  	 2-1

        2.1     Definition of Worst-Case Scenario  	 2-1
        2.2     Determination of Quantity for the Worst-Case Scenario	 2-3
        2.3     Selecting Worst-Case Scenarios	 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
                       Between 25 °C and 50 °C	  3-12

        3.3     Release Rates for Common Water Solutions of Toxic Substances and for Oleum	  3-14

4       Estimation of Worst-Case Distance to Toxic Endpoint 	 4-1


April 15, 1999                                       \

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                                   TABLE OF CONTENTS
                                          (Continued)
Chapter                                                                                    Page

5       Estimation of Distance to Overpressure Endpoint for Flammable Substances 	  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 Substances:
        13     Distance to Overpressure of 1.0 psi for Vapor Cloud Explosions
               of 500 - 2,000,000 Pounds  of Regulated Flammable Substances	  5-16

6       Determining Alternative Release Scenarios	  6-1

7       Estimation of Release Rates for Alternative Scenarios for Toxic Substances 	  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

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                                   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 Substances  	  8-1

9       Estimation of Release Rates for Alternative Scenarios for Flammable Substances	  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                                      111

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                                   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 Substances:
        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 Receptors	  11-1

12      Submitting Offsite Consequence Analysis  Information for Risk Management Plan	  12-1

        12.1    RMP Data Required for Worst-Case Scenarios for Toxic Substances	  12-1
        12.2    RMP Data Required for Alternative Scenarios for Toxic Substances  	  12-2
        12.3    RMP Data Required for Worst-Case Scenarios for Flammable Substances	  12-3
        12.4    RMP Data Required for Alternative Scenarios for Flammable Substances  	  12-3
        12.5    Submitting RMPs	  12-4
        12.6    Other Required Documentation	  12-4

APPENDICES

Appendix A:  References for Consequence Analysis Methods  	A-l

Appendix B:  Toxic Substances  	B-l

        B. 1     Data for Toxic Substances	B-l
        B.2     Mixtures  Containing Toxic Liquids	B-10


April 15, 1999                                     iv

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                                   TABLE OF CONTENTS
                                         (Continued)
APPENDICES                                                                           Page


Appendix C: Flammable Substances	  C-l

       C. 1     Equation for Estimation of Distance to 1 psi Overpressure for Vapor Cloud
               Explosions  	  C-l
       C.2     Mixtures of Flammable Substances	  C-l
       C.3     Data for Flammable Substances	  C-2

Appendix D: Technical Background	D-l

       D. 1     Worst-Case Release Rate for Gases  	D-l
               D. 1.1   Unmitigated Release  	D-l
               D. 1.2   Gaseous Release Inside Building	D-l

       D.2     Worst-Case Release Rate for Liquids 	D-l
               D.2.1   Evaporation Rate Equation	D-l
               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 Substances	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

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                                   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-l

       Worksheet 1.  Worst-case Analysis for Toxic Gas	  E-l
       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-l3

Appendix F: Chemical Accident Prevention Provisions	  F-l
April 15, 1999                                     VI

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                                      LIST OF EXHIBITS

Exhibit                                                                                      Page

1       Required Parameters for Modeling  	  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-l     Data for Toxic Gases	B-2

B-2     Data for Toxic Liquids	B-4

B-3     Data for Water Solutions of Toxic Substances and for Oleum	B-7

B-4     Temperature Correction Factors for Liquids Evaporating from Pools at Temperatures
        Between 25 °C and 50 °C (77 °F and 122 °F) 	B-8

C-l     Heats of Combustion for Flammable Substances	 C-3

C-2     Data for Flammable Gases	 C-6

C-3     Data for Flammable Liquids  	 C-9
April 15, 1999                                      vii

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                 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 CFRpart 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 NA1CS
       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
Chemical
manufacturers



Petroleum refineries
Pulp and paper
Food processors
Polyurethane foam
Non-metallic mineral
products
Metal products
NAICS
Codes
325




32411
322
311
32615
327
331
332
SIC
Codes
28




2911
26
20
3086
32
33
34
Examples of Potentially Regulated
Entities
Petrochemicals
Industrial gas
Alkalies and chlorine
Industrial inorganics
Industrial organics
Plastics and resins
Agricultural chemicals
Soap, cleaning compounds
Explosives
Miscellaneous chemical manufacturing
Petroleum refineries
Paper mills
Pulp mills
Paper products
Dairy products
Fruits and vegetables
Meat products
Seafood products
Plastic foam products
Glass and glass products
Other non-metallic mineral products
Primary metal manufacturing
Fabricated metal products
April 15, 1999
                                           Vlll

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Category
Machinery
manufacturing
Computer and
electronic equipment
Electric equipment
Transportation
equipment
Food distributors
Chemical distributors
Farm supplies
Propane dealers
Warehouses
Water treatment
Wastewater treatment
Electric utilities
Propane users
Federal facilities
NAICS
Codes
333
334
335
336
4224
4228
42269
42291
454312
4931
22131
22132
56221
22111


SIC
Codes
35
36
36
37
514
518
5169
5191
5171
5984
422
4941
4952
4933
4911


Examples of Potentially Regulated
Entities
Industrial machinery
Farm machinery
Other machinery
Electronic equipment
Semiconductors
Lighting
Appliance manufacturing
Battery manufacturing
Motor vehicles and parts
Aircraft
Frozen and refrigerated foods
Beer and wines
Chemical wholesalers
Agricultural retailers and wholesalers
Propane retailers and wholesalers
Refrigerated warehouses
Warehouse storing chemicals
Drinking water treatment systems
Sewerage systems
Wastewater treatment
Waste treatment
Electric power generation
Manufacturing facilities
Large institutions
Commercial facilities
Military installations
Department of Energy installations
April 15, 1999
                                                            IX

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                              Roadmap to Offsite Consequence Analysis Guidance by Type of Chemical
                           Type of Chemical and Release Scenario
         Applicable Sections and Appendices
                                                                    Toxic Gas
       Worst-Case Scenario
               1) Define Worst Case
               2) Select Scenario
               3) Calculate Release Rates
                       Unmitigated
                       Passive Mitigation
                       Refrigerated
               4) Find Toxic Endpoint
               5) Determine Reference Table and Distance
                       Dense or Neutrally Buoyant Plume
                       Chemical-Specific Tables (ammonia, chlorine, sulfur dioxide)
                       Urban or Rural
                       Release Duration
Section 2.1
Sections 2.2 and 2.3

Section 3.1.1
Section 3.1.2
Section 3.1.3
Appendix B (Exhibit B-1)
Section 3.1.3, 3.2.3
Chapter 4 and Appendix B (Exhibit B-l)
Chapter 4
Section 2.1 and Chapter 4
Section 2.1
       Alternative Scenario
               1) Define Alternative Scenario
               2) Select Scenario
               3) Calculate Release Rates
                       Unmitigated (from tanks and pipes)
                       Active or Passive Mitigation
               4) Find Toxic Endpoint
               5) Determine Reference Table and Distance
                       Dense or Neutrally Buoyant Plume
                       Chemical-Specific Tables (ammonia, chlorine, sulfur dioxide)
                       Urban or Rural
                       Release Duration
Chapter 6
Chapter 6

Section 7.1.1
Section 7.1.2
Appendix B (Exhibit B-1)

Chapter 8 and Appendix B (Exhibit B-l)
Chapter 8
Section 2.1 and Chapter 8
Section 7.1
April 15, 1999

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                       Roadmap to Offsite Consequence Analysis Guidance by Type of Chemical (continued)
                           Type of Chemical and Release Scenario
         Applicable Sections and Appendices
                                                                  Toxic Liquid
       Worst-Case Scenario
               1) Define Worst Case
               2) Select Scenario
               3) Calculate Release Rates
                       Releases from Pipes
                       Unmitigated Pool Evaporation
                       Passive Mitigation (dikes, buildings)
                       Release at Ambient Temperature
                       Release at Elevated Temperature
                       Releases of Mixtures
                       Temperature Corrections for Liquids at 25-50 °C
                       Releases of Solutions
               4) Find Toxic Endpoint
                       For Liquids/Mixtures
                       For Solutions
               5) Determine Reference Table and Distance
                       Dense or Neutrally Buoyant Plume (liquids)
                       Dense or Neutrally Buoyant Plume (solutions)
                       Chemical Specific Table (aqueous ammonia)
                       Urban or Rural
                       Release Duration (liquids)
                       Release Duration (solutions)
Section 2.1
Sections 2.2 and 2.3

Section 3.2.1
Section 3.2.2
Section 3.2.3
Section 3.2.2, 3.2.3
Section 3.2.2, 3.2.3
Section 3.2.4 and Appendix B (Section B.2)
Section 3.2.5 and Appendix B (Exhibit B-4)
Section 3.3 and Appendix B (Exhibit B-3)

Appendix B (Exhibit B-2)
Appendix B (Exhibit B-3)

Chapter 4 and Appendix B (Exhibit B-2)
Chapter 4 and Appendix B (Exhibit B-3)
Chapter 4
Section 2.1 and Chapter 4
Section 3.2.2
Chapter 4
April 15, 1999
                                                                       XI

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                       Roadmap to Offsite Consequence Analysis Guidance by Type of Chemical (continued)
                           Type of Chemical and Release Scenario
         Applicable Sections and Appendices
                                                                  Toxic Liquid
       Alternative Scenario
               1) Define Alternative Scenario
               2) Select Scenario
               3) Calculate Release Rates
                       Unmitigated (from tanks and pipes)
                       Active or Passive Mitigation
                       Release at Ambient Temperature
                       Release at Elevated Temperature
                       Release of Solution
               4) Find Toxic Endpoint
                       For Liquids/Mixtures
                       For Solutions
               5) Determine Reference Table and Distance
                       Dense or Neutrally Buoyant Plume (liquids/mixtures)
                       Dense or Neutrally Buoyant Plume (solutions)
                       Chemical-Specific Table (aqueous ammonia)
                       Urban or Rural
                       Release Duration (liquids/mixtures)
                       Release Duration (solutions)
Chapter 6
Chapter 6
Section 7.2
Section 7.2.1
Section 7.2.2
Section 7.2.3
Section 7.2.3
Sections 7.2.4 and 3.3 and Appendix B (Exhibit B-3)

Appendix B (Exhibit B-2)
Appendix B (Exhibit B-3)

Chapter 8 and Appendix B (Exhibit B-2)
Chapter 8 and Appendix B (Exhibit B-3)
Chapter 8
Section 2.1 and Chapter 8
Section 7.2
Chapter 8
April 15, 1999
                                                                      Xll

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                       Roadmap to Offsite Consequence Analysis Guidance by Type of Chemical (continued)
                           Type of Chemical and Release Scenario
         Applicable Sections and Appendices
                                                              Flammable Substance
       Worst-Case Scenario
               1) Define Worst Case
               2) Select Scenario
               3) Determine Distance to Overpressure Endpoint
                       For Pure Flammable Substances
                       For Flammable Mixtures
Sections 5.1 and 2.1
Sections 5.1, 2.2, and 2.3

Section 5.1
Section 5.2
       Alternative Scenario
               1) Define Alternative Scenario
               2) Select Scenario
               3) For Vapor Cloud Fires
                       Calculate Release Rates (gases)
                       Calculate Release Rates (liquids)
                       Find Lower Flammability Limit (gases)
                       Find Lower Flammability Limit (liquids)
                       Dense or Neutrally Buoyant (gases)
                       Dense or Neutrally Buoyant (liquids)
                       Urban or Rural
                       Release Duration
                       Determine Distance
               4) For Pool Fires
               5)ForBLEVEs
               6) For Vapor Cloud Explosions
Chapter 6
Chapter 6

Section 9.1 and Appendix C (Exhibit C-2)
Section 9.2 and Appendix C (Exhibit C-3)
Appendix C (Exhibit C-2)
Appendix C (Exhibit C-3)
Appendix C (Exhibit C-2)
Appendix C (Exhibit C-3)
Section 10.1
Section 10.1
Section 10.1
Section 10.2 and Appendix C (Exhibit C-3)
Section 10.3
Section 10.4
April 15, 1999
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April 15, 1999                                     xiv

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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 http://www.epa.gov/ceppo/.

        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 worst-case release scenario, and

+      Alternative release scenarios.

        To simplify the analysis and ensure comparability, EPA has defined the worst-case 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 short-term 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 worst-case 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.
April 15, 1999

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Chapter 1
Introduction
                                                      TM
                                         RMP*Comp
  To assist those using this guidance, the National Oceanic and Atmospheric Administration (NOAA) and
  EPA have developed a software program, RMP*Comp™, that performs the calculations described in
  this document. This software can be downloaded from the EPA/CEPPO Internet website at
  http://www.epa.gov/ceppo/ds-epds.htnrfcomp.
        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 substances, 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 distances 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 appropriate for the substance and scenario, you should consider choosing a different model 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*Submit system accepts only numerical
entries (i.e., it will not accept a "greater than" distance).  If you do enter a distance in RMP*Submit 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.
April 15, 1999
                                                1 -2

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                                              Exhibit 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.
For flammable substances, endpoint is overpressure of 1 pound per square
inch (psi) for vapor cloud explosions.
Endpoints for toxic substances are specified in part 68 Appendix A.
For flammable substances, endpoint is:
4-Overpressure of 1 psi for vapor cloud explosions, or
4-Radiant heat level of 5 kilowatts per square meter (kW/m2) for 40
seconds for heat from fires (or equivalent dose), or
4-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 meteorological
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 gathered 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(1))
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 14-17 for neutrally
buoyant gases and Tables 18-21 for dense gases, or Tables 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 at25°C or the boiling point of the released
substance, and also provides temperature correction factors.
Substances may be considered to be released at a process 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 temperature
correction factors.
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        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 carry 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 substances in Program 2  and
                Program 3  processes;

        •        One worst-case release scenario to represent all regulated flammable substances in Program
                2 and Program 3 processes;

        •        One alternative release scenario for each regulated toxic substance in Program 2 and
                Program 3  processes; and

        •        One alternative release scenario to represent all regulated flammable substances 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 facility would affect different public

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	Introduction

receptors. For example, worst-case release scenarios for 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-SPECIFIC RISK MANAGEMENT PROGRAMS

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

  •f      Propane storage facilities        +      Warehouses
  +      Chemical distributors           +      Ammonia refrigeration
  •f      Waste water treatment plants     +      Small propane retailers & users

  The industry-specific guidances are available from EPA at http://www.epa.gov/ceppo/.

  Industry-specific guidances developed by EPA take the place of this guidance document and the General
  Guidance for Risk Management Programs for the industries addressed.  If an industry-specific program
  exists for your process(es), you should use it as your basic guidance because it will provide more
  information that is specific to your process, including dispersion modeling.
        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 release. 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 distances obtained using these tables are not intended to be precise predictions of the exact
distances that 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-case 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 such  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 large 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,

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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 planning 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 carry out an offsite
consequence analysis. Before carrying out one or more worst-case and/or alternative release analyses, you
will need to obtain several pieces of information about the regulated substances you have, the area
surrounding your site, and typical meteorological conditions:

        •        Determine whether each regulated substance 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 substance.

        •        For toxic substances, determine whether the substance is stored as a gas, as a liquid, 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 substances.

        •        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-l  and B-2). For alternative scenarios
                involving a vapor cloud fire, you will also need this information for flammable substances
                (see Appendix C, Exhibits C-2 and C-3).

        •        For toxic substances, determine whether the topography (surface 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;

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	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 carrying 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 substances. Sections 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 carrying 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 parameters 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 duration 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 substances that are liquids 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:
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        •       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 substances and of oleum (Section 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 duration 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 substances (i.e., gases and liquids) (see
Appendix E, Worksheet 3,  for a worksheet for this analysis):

Step 1: Determine worst-case scenario.  Identify the appropriate flammable substance, quantity, and worst-
        case 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 substance, using the assumptions required by the rule
        (Chapter 5). This guidance provides  a reference table of distances (Reference Table 13) for worst-
        case 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 exists. (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).

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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 duration 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 substances that are liquids 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 substances and of oleum (Section 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 duration 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 substances (i.e., gases
and liquids) (see Appendix E, Worksheet 6, for a worksheet for this analysis):
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Step 1: Select alternative scenario.  Identify the flammable substance, and choose the quantity and type of
        event for the alternative scenario 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 (Section 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 released substance and the topography of your
               site, and  estimate distance to the endpoint 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 Reference 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 requirements may be found at 40 CFR part 68. The relevant
sections were published in the Federal Register on January 31, 1994 (59 FR4478)  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 January 6, 1998 (63 FR 640). A consolidated copy of these regulations is available in
Appendix F.

        EPA is working with industry and local, state, and federal government agencies to  assist sources in
complying with these requirements. For more information, refer to the General Guidance for Risk
Management Programs Appendix 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 federal levels for your questions.  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 at the home page of EPA's Chemical Emergency Preparedness and Prevention
Office (http://www.epa.gov/ceppo/). Please check the site regularly, as additional materials are posted when
they become available.  If you do not have  access to the Internet, you can call EPA's hotline at (800) 424-
9346.
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        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 substance 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 Appendix A to part 68 for toxic substances). 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
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 include 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 buildings or other obstructions (e.g., hills,
trees), you should assume open (rural) conditions. If your site is in an area with many obstructions, even if it
is in a remote location that would not usually be considered urban, you should assume urban conditions.

               Toxic Gases

        Toxic gases include all regulated toxic substances that are gases at ambient temperature (25 °C, 77
°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.

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        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 substances are  specified in the rule (40 CFR
part 68, Appendix A). Exhibit B-l of Appendix B lists the endpoint 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 carried in pipelines, 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 substance in the vessel, whichever is higher (40
CFR 68.25(d)(2)). The  release rate to air is estimated as the rate of evaporation 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, Appendix A).

                Flammable Substances

        For all regulated flammable substances, you must assume that the worst-case release results in a
vapor cloud containing the total quantity of the substance that could be released from a vessel or pipeline.
For the worst-case consequence analysis, you must assume the vapor cloud detonates. If you use a TNT-
equivalent 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 pound 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.)
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                                                                        Determining Worst-Case Scenarios
                Effect of Required Assumptions
        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 substance
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 amount in a single vessel. For substances 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 hazard (toxicity or flammability) for which a substance is regulated
(i.e., even if a regulated toxic substance is also flammable, you only need to consider toxicity in your analysis;
even if a regulated flammable substance 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 substance held above its threshold, you must
determine which substance produces the greatest distance to its endpoint and report on that substance. 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 substances present above the threshold quantity and one
worst-case analysis representing all flammable regulated substances present above the threshold  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 substance in a class, the substance chosen for the consequence
analysis for each  hazard for Program 2 and 3 processes should be the substance that has the potential to cause
the greatest offsite consequences. Choosing the toxic regulated substance that might lead to the greatest
offsite consequences may require a screening analysis of the toxic regulated substances on site, because the
potential consequences are dependent on a number of factors, including quantity, toxicity, and volatility.

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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 substances for the worst-case analysis for Program 2 or
                3 if you have  other regulated toxics, but you may want to consider carrying out a worst-case
                analysis to demonstrate potential Program 1 eligibility.

        For flammable substances, you must consider the consequences of a vapor cloud 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 cloud, its heat of combustion, and other factors that are assumed to be the same for all
flammable substances.  In most cases, the  analysis probably should 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 combustion.  In
some cases, a regulated flammable substance that is close to the fenceline might have a greater potential
offsite impact than a larger quantity farther from the fenceline.

        You are likely to estimate smaller worst-case distances for flammable substances than for similar
quantities of most toxic substances. Because the distance to the endpoint may be relatively small, you may
find it worthwhile to carry out  a worst-case analysis  for each process containing flammable substances to
demonstrate potential eligibility for Program 1, unless there are public receptors close to the process.
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        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 substances 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 substance.  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.
        Regulated substances that are gases at ambient temperature (25 °C, 77 °F) should 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 refrigeration alone that would form a pool
one centimeter (0.033 foot) or less in depth should 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.
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                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:
                                                                                               (3-1)
                                                      10
where:
QR
QS
Release rate (pounds per minute)
Quantity released (pounds)
   Example 1. Gas Release (Diborane)

   You have a tank containing 2,500 pounds 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 pounds/10 minutes = 250 pounds 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:
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                                         OR  =     . x  0.55
                                                 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 pounds per minute.
   The mitigated release to the outside air from the building would be:

                  QR = 250 pounds/minute x 0.55 = 138 pounds 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 assuming 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-l 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 substance.  Use Equation 3-
8 in Section 3.2.3 for the release rate.  The Liquid Factor Boiling (LFB) for each toxic gas, needed to use
Equation 3-8, is listed in Exhibit B-l 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 substances, 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.)

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

   You have a refrigerated tank containing 50,000 pounds of liquid chlorine at ambient pressure.  A diked area
   around the chlorine tank of 275 square feet is sufficient to hold all of the spilled liquid chlorine. Once the
   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 x 0.19 x 275 = 73 pounds 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:

                              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
                      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
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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 liquids (other than gases liquefied by
refrigeration) are released at the highest maximum daily temperature for the previous three years or at process
temperature, whichever is higher.  This chapter provides methods to estimate the release rate at 25 °C (77 °F)
or at the boiling point, and also provides a method to correct the release rate at 25 °C for releases at
temperatures between 25 °C and 50 °C.

        The calculation methods provided in this section apply to substances that are liquids 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 shear). Therefore, the length would be the full length of pipe
carrying 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 Appendix B, Exhibit B-2. Density in
pounds per cubic foot is equal to  1/(DF times 0.033).) Assume the estimated quantity (in pounds) 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
Factor (DF) in Exhibit B-2 of Appendix B. The LFA and DF apply to liquids  at 25 °C; if your ambient
temperature is between 25  °C and 50 °C, you may use the method described here and then apply a
Temperature Correction Factor (TCP), as discussed in Section 3.2.5 below, to correct the calculated release
rate. Calculate the release  rate of the liquid at 25 °C from the following equation:

                                 QR = QS x 1.4  x LFA x DF                            (3-3)
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where:
QR
QS
1.4

LFA
DF
Release rate (pounds per minute)
Quantity released (pounds)
Wind speed factor = 1.5078, where 1.5 meters per second (3.4 miles per
hour) is the wind speed for the worst case
Liquid Factor Ambient
Density Factor
   Example 4. Unmitigated Liquid Release at Ambient Temperature (Acrylonitrile)

   You have a tank containing 20,000 pounds 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 x 1.4x0.018x0.61 = 307 pounds per minute

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

                          t = 20,000 pounds/307 pounds per minute = 65 minutes
                       Elevated Temperature

        If the liquid is at an elevated temperature (above 50 °C or at or close to the boiling point), find the
Liquid Factor Boiling (LFB) 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 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.
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 x  1.4 x LFB  x  DF
                                                                               (3-4)
where:
QR
QS
1.4

LFB
DF
Release rate (pounds per minute)
Quantity released (pounds)
Wind speed factor = 1.5078, where 1.5 meters per second (3.4 miles per
hour) is the wind speed for the worst case
Liquid Factor Boiling
Density Factor
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   Example 5. Unmitigated Release at Elevated Temperature (Acrylonitrile)

   You have a tank containing 20,000 pounds 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 x  1.4x0.11  x 0.61 = 1,880 pounds per minute

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

                   t = 20,000 pounds/1880 pounds 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
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:
where:          t       =       Duration of the release (minutes)
                QR     =       Release rate (pounds per minute) (use release rate corrected for
                                temperature, QRc, if appropriate)
                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:
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                                         A =  QS x 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 (LFB), if the liquid is at an elevated temperature. For liquids at
temperatures between 25 °C and 50 °C, you may use the method described here and then apply a
Temperature Correction Factor (TCP),  as discussed in Section 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  x LFA  x A                                (3-7)

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

                                      QR =  1.4  x LFB  x A                                (3-8)

where:         QR     =      Release rate (pounds per minute)
                1.4     =      Wind speed factor = 1.5078, 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 x DF  x 0.033 (DF x 0.033 is
               equal to I/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.

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                        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 surface 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)

   You have a tank containing 20,000 pounds 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 x 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 x 0.16 x
   0.033, or 106 cubic feet. The spilled 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  x 0.073 x 100 = 10 pounds per minute

   The maximum duration of the release would be:

                          t = 20,000 pounds/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.
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                       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 x  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 obstacles.

        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 hour)), using 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:

                                         QRB = 0.1  x  QR                                (3.10)

where:          QRB   =       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.
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   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 x 0.073 x 100 = 10 pounds per minute

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

                   QRB = 0.1 x 10 pounds per minute = 1 pound per minute
                3.2.4   Mixtures Containing Toxic Liquids

        Mixtures containing regulated toxic substances do not have to be considered if the concentration of
the regulated substance in the mixture is below one percent by weight or if you can demonstrate that the
partial vapor pressure of the regulated substances in the mixture is below 10 millimeters of mercury (mm
Hg).  Regulated substances present as by-products 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 Sections 3.2.2 or 3.2.3 using the quantity of the
                regulated substance in the mixture and the liquid factor (LFA or LFB) and density factor for
                the regulated substance in pure form.  This is a simple approach that likely will give
                conservative results.

        •       If you know the partial pressure of the regulated substance 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 substance (in most cases, this assumption is unlikely to have a large
                        effect on the results).

        •       You may estimate  the partial pressure of the regulated substance 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

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                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 solutions 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.
                   OR= 0.0035  x l.Q x (53.06r/a x 30.500 x  51.
                                               298
                   QR = 262 pounds per minute
   Example 8.  Mixture Containing Toxic Liquid (Acrylonitrile)

   You have a tank containing 50,000 pounds 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 pounds; N,N-dimethylformamide = 30,000 pounds.) 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,=	(20.000/53.061
                       (20,000/53.06) + (30,000/73.09)

                   Xr=    377
                       377+410

                   >^ = 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):
                   VPm = 0.48x 108 = 51.8 mmHg

   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 pounds
   and the Density Factor for acrylonitrile is 0.61 in Exhibit B-2; therefore:

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

   Now calculate the evaporation rate for acrylonitrile in the mixture from Equation B-5 using the VPm and A
   calculated above:
                3.2.5   Release Rate Correction for Toxic Liquids Released at Temperatures
                        Between 25 °C and 50 °C

        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

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                                                                                           Chapter 3
                                                                      Release Rates for Toxic Substances
°C to estimate from a pool at the higher temperature using Temperature Correction Factors (TCP) provided in
Appendix B, Exhibit B-4.  Calculate a corrected release rate as follows:

        •      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 TCP for your liquid in the column for the appropriate temperature.

        •      Estimate a corrected release rate (QRc) by multiplying the estimated release rate by the TCP;
               i.e.,

                                       QRC =  QR x  TCP                               (3.11)


               where:  QRC    =       Corrected release rate
                       QR     =       Release rate calculated for 25 °C
                       TCP    =       Temperature Correction Factor (from Exhibit B-4, Appendix 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.
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Chapter 3
Release Rates for Toxic Substances
   Example 9. Liquid Release at Ambient Temperature Between 25 °C and 50 °C (Bromine)

   Assume the tank containing 20,000 pounds of bromine, from Example 6, is at an ambient temperature of 35 °C
   (95 °F). As in Example 6, the total quantity in the tank is spilled into a diked enclosure that completely contains
   the spill.  The surface area is 100 square feet. In Example 6, the release rate (QR) at 25 °C was calculated from
   Equation  3-7 to be 10 pounds per minute.  To adjust the release rate for the temperature of 35 °C, you find the
   Temperature Correction Factor (TCP) for bromine at 35 °C from Exhibit B-4 in Appendix B. The TCP at this
   temperature is 1.5; the corrected release rate (QRC) at 3 5 °C, from Equation 3 -11, is

                                  QRC =10x1.5 = 15 pounds per minute

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

                         t = 20,000 pounds/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 solution of sulfur trioxide in sulfuric acid) also is discussed in this section.

        The vapor pressure and evaporation rate of a substance in solution depends on its concentration in
the solution. If a concentrated water solution containing a volatile toxic substance is spilled, 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 substance in the solution decreases.  At
much lower concentrations, water may evaporate more quickly than the toxic substance.  There is one
concentration at which the composition of the solution does not change as evaporation occurs.  For most
situations of interest, the concentration exceeds this concentration, and the toxic substance evaporates more
quickly than water.

        For estimating release rates from solutions, this guidance lists liquid 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
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                                                                                             Chapter 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 pool 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 substance will 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 substance in solution. Use the
               total quantity of the solution as the quantity released (QS) in carrying 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.
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Chapter 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 pounds 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 x 9,000 x 0.0085 = 107 pounds 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 substance and its release rate from the solution will be much higher. This
                guidance does not include temperature correction factors for evaporation rates of regulated
                substances from solutions. If you know the partial vapor pressure of the toxic substance in
                solution at the relevant temperature, you can carry out the calculation 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 substance from the solution will decrease rapidly as its
                concentration decreases.

        •       Unknown Vapor Pressure. If you do not know the vapor pressure of the substance 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 substances includes several substances that, in their pure form,  are
                        gases under ambient conditions, but that may commonly be found in water
                        solutions. These substances include 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 solution is released as a gas over 10

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                                                                                               Chapter 3
                                                                        Release Rates for Toxic Substances
                        minutes, as discussed in Section 3.1 above. You may determine the amount of pure
                        substance in the solution 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 pounds 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 x 0.37 pounds of hydrogen chloride, or 18,500 pounds. You assume the
   entire 18,500 pounds is released over 10 minutes. From Equation 3-1, the release rate is 18,500 divided by 10,
   or 1,850 pounds 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
                        between 25 °C and 50 °C, you may use the LFA and the temperature correction
                        factors for the pure substance, as described in Section 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 substance remaining
                        inside the diked area and the quantity of pure substance spilled outside the diked
                        area in carrying out the release rate analysis as discussed in Section 3.2.3.

April 15, 1999                                       3-17

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Chapter 3
Release Rates for Toxic Substances
   Example 12. Evaporation Rate for Liquid in Water Solution at Elevated Temperature (Nitric Acid)

   You have 18,000 pounds of 90 percent nitric acid solution in a high temperature process.  The solution would
   contain 18,000 x 0.90 pounds of nitric acid, or 16,200 pounds. You assume 16,200 pounds 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 Boiling
   (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 x 1.4 x 0.12 x 0.32 = 870 pounds 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

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        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 carried out to develop separate reference tables. These generic reference
tables can be used to estimate distances using the specified toxic endpoint for each substance 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 speed
of 1.5 meters per second (3.4 miles per hour) and F stability.  To use the reference tables, you need the worst-
case 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 less; 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 Equation 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 ammonia, 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, 1999

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Chapter 4
Estimation of Worst-Case Distance to Toxic Endpoint
        Remember that these reference tables provide 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 Substances Other than Ammonia, Chlorine, and Sulfur Dioxide

        •        Find the toxic endpoint for the substance in Appendix 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-l 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 obstructions.

                       Use the urban table if your site is in an urban or obstructed area.  The urban tables
                       are appropriate if there are many obstructions 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                                       4-2

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                                                                                          Chapter 4
                                                      Estimation of Worst-Case Distance to Toxic Endpoint
                                             Exhibit 2
                   Generic Reference Tables of Distances for Worst-case Scenarios
Applicable Conditions
Gas or Vapor Density
Neutrally buoyant
Dense
Topography
Rural
Urban
Rural
Urban
Release Duration
(minutes)
10
60
10
60
10
60
10
60
Reference Table
Number
1
2
3
4
5
6
7
8
                                             Exhibit 3
             Chemical-Specific Reference Tables of Distances for Worst-case Scenarios
Substance
Anhydrous ammonia
liquefied under pressure
Non-liquefied ammonia,
ammonia liquefied by
refrigeration, or aqueous
ammonia
Chlorine
Sulfur dioxide (anhydrous)
Applicable Conditions
Gas or Vapor
Density
Dense
Neutrally buoyant
Dense
Dense
Topography
Rural, Urban
Rural, Urban
Rural, Urban
Rural, Urban
Release Duration
(minutes)
10
10
10
10
Reference
Table
Number
9
10
11
12
April 15, 1999
                                               4-:

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Chapter 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 substance
                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 substance by reading across the top of
                       the table. If the endpoint of the substance 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 substance 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 substance.

        For Ammonia, Chlorine, or Sulfur Dioxide

        •       Find the appropriate chemical-specific table for your substance (see the descriptions 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
                       obstructions.
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                                                                                             Chapter 4
                                                        Estimation of Worst-Case Distance to Toxic Endpoint
                       Use the urban column if your site is in an urban or obstructed area.  The urban
                       column is appropriate if there are many obstructions 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 DA.2.
The development of Reference Tables 9-12 is discussed in industry-specific risk management program
guidance documents and a backup information document that are cited in Section DAS. 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 Hazardous Atmospheres (ALOHA) and the World Bank Hazards 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 carried out for development of
the reference tables of distances. Appendix D, Section DAS, provides information on the modeling carried
out with ALOHA and WHAZAN.
   Example 13. Gas Release (Diborane)

   In Example 1, you estimated a release rate for diborane gas of 250 pounds 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                                       4-5

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Chapter 4
Estimation of Worst-Case Distance to Toxic Endpoint
   Example 14. Gas Release (Ethylene Oxide)

   You have a tank containing 10,000 pounds 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 pounds/10 minutes = 1,000 pounds per minute

   From Exhibit B-l, 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 pounds 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 pounds per minute for acrylonitrile from a pool formed by the release
   of 20,000 pounds 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 pounds per minute is 250 pounds 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 pounds 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 pounds per minute,
   using the same assumptions and the dense cloud dispersion model.
April 15, 1999
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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 cloud 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 substance. The method 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 substance is in the cloud 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 substance that is not in a mixture with other
substances, you may estimate the consequence distance for a given quantity of a regulated flammable
substance using Reference Table  13.  This table provides distances to 1 psi overpressure  for vapor cloud
explosions of quantities from 500 to 2,000,000 pounds. These distances were estimated  by a TNT-
equivalent model, Equation C-l in Appendix C, Section C. 1, using the worst-case assumptions described
above and data provided in Exhibit C-l, Appendix C. If you prefer, you may calculate your worst-case
consequence distance for flammable substances from the heat of combustion of the flammable substance and
Equation C-l or C-2.
April 15, 1999

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Chapter 5
Estimation of Distance to Overpressure Endpoint for Flammable Substances
   Example 16. Vapor Cloud Explosion (Propane)

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

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

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

                          D = 0.3 miles
        5.2    Flammable Mixtures

        If you have more than 10,000 pounds of a mixture of flammable substances that meets the criteria
for listing under CAA section 112(r) (flash point below 22.8 °C (73 °F), boiling point below 37.8 °C (100
°F), National Fire Protection Association (NFPA) flammability hazard rating of 4), you may need to carry 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 substances.)  You
should carry out the analysis using the total quantity of all regulated flammable substance 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 should include them in the quantity used in the analysis.

        For simplicity, you may carry out the worst-case analysis based on the predominant regulated
flammable component of the mixture or a major component of the mixture with the highest heat of
combustion if the whole vapor cloud consists of flammable substances (see Exhibit C-l, Appendix 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-l 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 -'.

-------
                                                                                                  Chapter 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 pounds of ethylene (the reactant) and 2,000 pounds 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:

                            HCm = [ (8,000/2.2)  x 47,145 1 + [ (2,000/2.2)  x  45,576]
                                     (10,000/2.2)                 (10,000/2.2)

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

                            HCm = 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 x  [ 0.1 x 10,000 x (46,831/4,680) ]1/'

                            D = 0.2 miles
   Example 18. Vapor Cloud Explosion of Flammable Mixture (Ethylene and Isobutane)

   You have 10,000 pounds 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-l, Appendix C). From
   Reference Table 13, the distance to 1 psi overpressure is 0.2 miles for 10,000 pounds of ethylene; this distance
   would also apply to the 10,000-pound mixture of ethylene and isobutane.
April 15, 1999

-------
                                      Reference Table 1
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        10-Minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-4.4
4.4-37
37-97
97- 180
180-340
340 - 530
530 - 760
760- 1,000
1,000-1,500
1,500- 1,900
1,900-2,400
2,400 - 2,900
2,900 - 3,500
3,500 - 4,400
4,400 - 5,100
5,100 - 5,900
5,900 - 6,800
6,800 - 7,700
7,700 - 9,000
9,000 - 10,000
10,000-11,000
11,000- 12,000
12,000 - 14,000
14,000- 15,000
15,000-16,000
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
16,000-18,000
18,000- 19,000
19,000-21,000
21,000-23,000
23,000 - 24,000
24,000 - 26,000
26,000 - 28,000
28,000 - 29,600
29,600 - 35,600
35,600 - 42,000
42,000 - 48,800
48,800 - 56,000
56,000 - 63,600
63,600-71,500
71,500-88,500
88,500 - 107,000
107,000 - 126,000
126,000 - 147,000
147,000 - 169,000
169,000- 191,000
191,000-215,000
215,000-279,000
279,000 - 347,000
>347,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                             5-4

-------
                                      Reference Table 2
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        60-Minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-5.5
5.5-46
46 - 120
120-220
220 - 420
420 - 650
650-910
910-1,200
1,200- 1,600
1,600-1,900
1,900-2,300
2,300 - 2,600
2,600 - 2,900
2,900 - 3,400
3,400 - 3,700
3,700-4,100
4,100-4,400
4,400 - 4,800
4,800 - 5,200
5,200 - 5,600
5,600 - 5,900
5,900 - 6,200
6,200 - 6,700
6,700 - 7,000
7,000 - 7,400
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
7,400 - 7,700
7,700 - 8,100
8,100 - 8,500
8,500 - 8,900
8,900 - 9,200
9,200 - 9,600
9,600 - 10,000
10,000 - 10,400
10,400- 11,700
11,700-13,100
13,100- 14,500
14,500-15,900
15,900- 17,500
17,500-19,100
19,100-22,600
22,600 - 26,300
26,300 - 30,300
30,300 - 34,500
34,500 - 38,900
38,900 - 43,600
43,600 - 48,400
48,400-61,500
61,500-75,600
>75,600
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                             5 - 5

-------
                                      Reference Table 3
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        10-minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-21
21 - 170
170-420
420 - 760
760-1,400
1,400-2,100
2,100-3,100
3,100-4,200
4,200-6,100
6,100-7,800
7,800 - 9,700
9,700 - 12,000
12,000 - 14,000
14,000- 18,000
18,000-22,000
22,000 - 25,000
25,000 - 29,000
29,000 - 33,000
33,000 - 39,000
39,000 - 44,000
44,000 - 49,000
49,000 - 55,000
55,000 - 63,000
63,000 - 69,000
69,000 - 76,000
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
76,000 - 83,000
83,000 - 90,000
90,000-100,000
100,000- 110,000
110,000-120,000
120,000- 130,000
130,000-140,000
140,000 - 148,000
148,000-183,000
183,000-221,000
221,000-264,000
264,000-310,000
310,000-361,000
361,000-415,000
415,000-535,000
535,000-671,000
671,000-822,000
822,000 - 990,000
990,000-1,170,000
1,170,000- 1,370,000
1,370,000-1,590,000
1,590,000-2,190,000
2,190,000-2,890,000
>2,890,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                             5-6

-------
                                      Reference Table 4
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        60-Minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-26
26-210
210-530
530 - 940
940-1,700
1,700-2,600
2,600 - 3,700
3,700 - 4,800
4,800 - 6,400
6,400 - 7,700
7,700 - 9,100
9,100- 11,000
11,000-12,000
12,000 - 14,000
14,000 - 16,000
16,000 - 17,000
17,000-19,000
19,000-21,000
21,000-23,000
23,000 - 24,000
24,000 - 26,000
26,000 - 28,000
28,000 - 30,000
30,000 - 32,000
32,000 - 34,000
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
34,000 - 36,000
36,000 - 38,000
38,000-41,000
41,000-43,000
43,000 - 45,000
45,000 - 47,000
47,000 - 50,000
50,000 - 52,200
52,200 - 60,200
60,200 - 68,900
68,900 - 78,300
78,300 - 88,400
88,400 - 99,300
99,300- 111,000
111,000-137,000
137,000- 165,000
165,000-197,000
197,000-232,000
232,000-271,000
271,000-312,000
312,000-357,000
357,000 - 483,000
483,000 - 629,000
>629,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                      *Report distance as 25 miles
April 15, 1999
                                             5-7

-------
                                                               Reference Table 5
                                                     Dense Gas Distances to Toxic Endpoint
                                10-minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (mg/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
2.2
3.0
4.8
6.8
11
14
19
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.7
2.4
3.7
5.0
8.7
11
15
18
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.5
2.1
3.0
4.2
6.8
9.3
12
15
19
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.1
1.5
2.2
3.0
5.2
6.8
8.7
11
14
19
23
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.8
1.1
1.7
2.4
3.9
5.0
6.8
8.1
11
14
17
20
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
0.7
0.9
1.5
2.1
3.4
4.2
5.8
6.8
8.7
12
15
17
20
23
>25
*
*
*
*
*
*
*
*
*
*
*
*
0.5
0.7
1.2
1.7
2.8
3.5
4.8
5.7
7.4
9.9
12
14
16
19
20
23
>25
*
*
*
*
*
*
*
*
*
*
0.5
0.7
1.0
1.4
2.4
3.0
4.2
5.0
6.2
8.7
11
12
14
16
18
20
22
25
>25
*
*
*
*
*
*
*
*
0.3
0.4
0.7
1.0
1.7
2.2
2.9
3.6
4.5
6.2
7.4
8.1
9.9
11
12
14
16
17
20
24
>25
*
*
*
*
*
*
0.2
0.3
0.5
0.7
1.3
1.7
2.2
2.7
3.4
4.7
5.5
6.2
7.4
8.7
9.3
9.9
11
13
15
17
20
23
>25
*
*
*
*
0.2
0.3
0.4
0.6
1.1
1.4
1.9
2.3
2.8
3.8
4.5
5.2
6.2
6.8
8.1
8.7
9.3
11
12
14
17
19
>25
*
*
*
*
0.2
0.2
0.3
0.5
0.9
1.1
1.6
1.9
2.3
3.1
3.7
4.2
5.0
5.6
6.2
6.8
7.4
8.7
9.9
11
13
15
21
>25
*
*
*
0.1
0.2
0.3
0.4
0.7
0.9
1.3
1.6
2.0
2.7
3.2
3.6
4.3
4.8
5.3
5.6
6.2
6.8
8.7
9.3
11
12
18
21
24
>25
*
0.1
0.1
0.2
0.2
0.4
0.6
0.8
0.9
1.2
1.6
1.9
2.2
2.5
2.9
3.2
3.4
3.8
4.2
4.9
5.5
6.2
7.4
10
12
13
15
17
#
<0.1
0.1
0.2
0.3
0.4
0.5
0.6
0.8
1.1
1.3
1.4
1.7
1.9
2.1
2.2
2.5
2.7
3.2
3.6
4.2
4.7
6.6
7.6
8.5
9.8
11
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.6
0.9
1.0
1.1
1.3
1.5
1.6
1.7
2.0
2.1
2.5
2.8
3.2
3.7
5.0
5.8
6.4
7.4
8.2
* > 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                                     5-:

-------
                                                              Reference Table 6
                                                     Dense Gas Distances to Toxic Endpoint
                                60-minute Release, Rural Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (mg/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
3.7
5.3
8.7
12
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
2.7
4.0
6.8
9.3
16
21
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
2.2
3.2
5.3
8.1
14
18
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.4
2.2
3.7
5.3
9.9
12
18
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.0
1.6
2.7
4.0
7.4
9.3
13
17
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.8
1.2
2.2
3.3
6.1
8.1
11
14
18
25
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.6
1.0
1.7
2.7
4.9
6.2
9.3
11
14
20
25
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.5
0.8
1.4
2.2
4.1
5.4
7.4
9.9
12
17
22
25
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.3
0.5
0.9
1.4
2.9
3.8
5.5
6.8
8.7
12
15
17
20
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
0.2
0.4
0.6
1.0
2.1
2.7
4.0
4.9
6.2
9.3
11
12
16
17
20
21
24
>25
*
*
*
*
*
*
*
*
*
0.2
0.3
0.5
0.8
1.6
2.2
3.2
4.0
5.2
7.4
9.3
11
12
14
16
17
20
22
>25
*
*
*
*
*
*
*
*
0.1
0.2
0.4
0.6
1.2
1.7
2.5
3.1
4.1
5.8
7.4
8.1
9.9
11
13
14
16
17
21
24
>25
*
*
*
*
*
*
0.1
0.2
0.3
0.5
1.0
1.4
2.1
2.7
3.5
5.0
6.1
6.8
8.7
9.9
11
12
14
15
18
20
24
>25
*
*
*
*
*
<0.1
0.1
0.2
0.3
0.5
0.7
1.1
1.4
1.9
2.9
3.5
4.0
5.0
5.7
6.2
6.8
8.1
8.7
11
12
14
16
22
>25
*
*
*
#
<0.1
0.1
0.2
0.3
0.4
0.7
0.9
1.2
1.8
2.2
2.6
3.2
3.7
4.2
4.5
5.2
5.7
6.8
7.4
9.3
9.9
14
17
18
21
23
#
<0.1
0.1
0.1
0.2
0.3
0.5
0.6
0.9
1.3
1.7
2.0
2.5
2.9
3.2
3.5
4.0
4.4
5.2
6.0
6.8
8.1
11
13
14
16
18
* > 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                                     5-9

-------
                                                               Reference Table 7
                                                     Dense Gas Distances to Toxic Endpoint
                                10-minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (mg/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
1.6
2.2
3.5
4.9
8.1
11
15
19
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.2
1.7
2.7
3.8
6.2
8.1
11
14
18
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.1
1.4
2.2
3.1
5.3
6.8
9.3
12
15
21
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.7
1.1
1.6
2.2
3.7
4.8
6.8
8.1
11
15
18
21
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.6
0.8
1.2
1.7
2.9
3.7
5.2
6.1
8.1
11
14
16
19
22
24
>25
*
*
*
*
*
*
*
*
*
*
*
0.4
0.6
1.0
1.4
2.4
3.1
4.2
5.2
6.8
9.3
11
13
16
18
20
22
25
>25
*
*
*
*
*
*
*
*
*
0.4
0.5
0.8
1.2
2.0
2.5
3.5
4.3
5.4
7.4
9.3
11
12
15
16
18
20
23
>25
*
*
*
*
*
*
*
*
0.3
0.4
0.7
1.0
1.7
2.1
3.0
3.6
4.6
6.2
8.1
9.3
11
12
14
16
17
20
24
>25
*
*
*
*
*
*
*
0.2
0.3
0.5
0.7
1.2
1.5
2.1
2.5
3.3
4.5
5.5
6.2
7.4
8.7
9.9
11
12
14
16
19
22
>25
*
*
*
*
*
0.2
0.2
0.4
0.5
0.9
1.1
1.6
1.9
2.4
3.4
4.1
4.6
5.6
6.2
6.8
7.4
8.7
9.9
12
14
16
19
>25
*
*
*
*
0.1
0.2
0.3
0.4
0.7
0.9
1.3
1.6
2.0
2.8
3.3
3.8
4.6
5.2
5.8
6.2
6.8
8.1
9.9
11
13
15
23
>25
*
*
*
0.1
0.1
0.2
0.3
0.6
0.7
1.0
1.2
1.6
2.2
2.6
3.0
3.7
4.1
4.7
5.0
5.6
6.2
7.4
8.7
11
12
17
21
24
>25
*
0.1
0.1
0.2
0.2
0.4
0.6
0.9
1.1
1.4
1.9
2.2
2.5
3.0
3.5
3.8
4.2
4.8
5.3
6.2
7.4
8.7
9.9
15
17
20
23
>25
#
<0.1
0.1
0.1
0.2
0.3
0.5
0.6
0.7
1.1
1.3
1.5
1.7
2.0
2.2
2.4
2.7
3.0
3.6
4.1
4.9
5.5
8.1
9.6
11
13
14
#
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.7
0.8
0.9
1.1
1.3
1.4
1.6
1.7
1.9
2.3
2.6
3.1
3.5
5.1
6.0
6.8
8.1
8.9
#
#
#
<0.1
0.1
0.1
0.2
0.2
0.3
0.5
0.6
0.7
0.8
0.9
1.1
1.2
1.3
1.4
1.7
2.0
2.3
2.7
3.8
4.5
5.1
6.1
6.7
* > 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                                    5- 10

-------
                                                               Reference Table 8
                                                     Dense Gas Distances to Toxic Endpoint
                                60-minute Release, Urban Conditions, F Stability, Wind Speed 1.5 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (mg/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
2.6
3.8
6.2
9.3
16
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.9
2.9
4.7
6.8
12
16
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.5
2.3
3.9
5.6
9.9
14
20
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
1.1
1.5
2.6
3.9
7.4
9.3
14
17
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.7
1.1
1.9
2.9
5.3
6.8
9.9
12
16
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.6
0.9
1.5
2.3
4.3
5.7
8.1
11
14
19
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.4
0.7
1.2
1.8
3.4
4.5
6.8
8.1
11
16
19
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.4
0.6
0.9
1.5
2.9
3.8
5.7
6.8
9.3
13
16
19
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
0.2
0.4
0.6
0.9
1.9
2.6
3.8
4.8
6.2
9.3
11
13
16
19
20
22
>25
*
*
*
*
*
*
*
*
*
*
0.2
0.2
0.4
0.7
1.3
1.8
2.7
3.5
4.5
6.8
8.1
9.3
12
13
15
16
19
21
>25
*
*
*
*
*
*
*
*
0.1
0.2
0.3
0.5
1.0
1.4
2.2
2.8
3.7
5.4
6.8
7.4
9.3
11
12
13
16
17
20
24
>25
*
*
*
*
*
*
0.1
0.1
0.2
0.4
0.7
1.1
1.7
2.2
2.9
4.2
5.2
6.0
7.4
8.7
9.3
11
12
14
16
19
22
>25
*
*
*
*
*
0.1
0.1
0.2
0.3
0.6
0.9
1.4
1.8
2.4
3.5
4.3
5.0
6.2
7.4
8.1
8.7
9.9
11
14
16
19
21
>25
*
*
*
*
#
<0.1
0.1
0.2
0.3
0.4
0.7
0.9
1.2
1.9
2.4
2.8
3.4
4.0
4.5
4.9
5.6
6.2
7.4
8.7
11
12
18
21
24
>25
*
#
#
<0.1
0.1
0.2
0.2
0.4
0.5
0.7
1.1
1.4
1.6
2.1
2.5
2.8
3.0
3.5
4.0
4.8
5.5
6.8
7.4
11
13
15
18
20
#
#
#
<0.1
0.1
0.2
0.3
0.3
0.5
0.7
1.0
1.2
1.5
1.8
2.1
2.2
2.6
3.0
3.6
4.2
5.1
5.8
8.7
10
11
14
15
* > 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                                    5- 11

-------
                                        Reference Table 9
           Distances to Toxic Endpoint for Anhydrous Ammonia Liquefied Under Pressure
                          F Stability, Wind Speed 1.5 Meters per Second
Release Rate
(Ibs/min)
1
2
5
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
750
800
900
Distance to Endpoint (miles)
Rural
0.1
0.1
0.1
0.2
0.2
0.3
0.3
0.4
0.4
0.5
0.5
0.5
0.6
0.6
0.7
0.8
0.9
1.0
1.2
1.3
1.4
1.5
1.6
1.6
1.7
Urban
0.1*
0.1
0.1
0.1
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.4
0.4
0.4
0.5
0.6
0.6
0.7
0.8
0.9
0.9
1.0
1.0
1.1
1.2
Release Rate
(Ibs/min)
1,000
1,500
2,000
2,500
3,000
4,000
5,000
6,000
7,000
7,500
8,000
9,000
10,000
15,000
20,000
25,000
30,000
40,000
50,000
75,000
100,000
150,000
200,000
250,000
750,000
Distance to Endpoint (miles)
Rural
1.8
2.2
2.6
2.9
3.1
3.6
4.0
4.4
4.7
4.9
5.1
5.4
5.6
6.9
8.0
8.9
9.7
11
12
15
18
22
**
**
**
Urban
1.2
1.5
1.7
1.9
2.0
2.3
2.6
2.8
3.1
3.2
3.3
3.4
3.6
4.4
5.0
5.6
6.1
7.0
7.8
9.5
10
13
15
17
**
*Report distance as 0.1 mile
** More than 25 miles (report distance as 25 miles)
April 15, 1999
                                              5-12

-------
                                       Reference 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
(Ibs/min)
1
2
5
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
750
800
900
Distance to Endpoint (miles)
Rural
0.1
0.1
0.1
0.2
0.2
0.3
0.3
0.4
0.4
0.4
0.5
0.5
0.5
0.6
0.7
0.8
0.8
0.9
1.1
1.2
1.3
1.4
1.4
1.5
1.5
Urban
0.1*
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.4
0.4
0.4
0.5
0.5
0.5
0.6
Release Rate
(Ibs/min)
1,000
1,500
2,000
2,500
3,000
4,000
5,000
6,000
7,000
7,500
8,000
9,000
10,000
15,000
20,000
25,000
30,000
40,000
50,000
75,000
100,000
150,000
200,000
250,000
750,000
Distance to Endpoint (miles)
Rural
1.6
2.0
2.2
2.5
2.7
3.1
3.4
3.7
4.0
4.1
4.2
4.5
4.7
5.6
6.5
7.2
7.8
8.9
9.8
12
14
16
19
21
**
Urban
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.5
1.6
1.7
2.0
2.4
2.6
2.8
3.3
3.6
4.4
5.0
6.1
7.0
7.8
13
*Report distance as 0.1 mile
** More than 25 miles (report distance as 25 miles)
April 15, 1999
                                              5-13

-------
                                        Reference Table 11
                             Distances to Toxic Endpoint for Chlorine
                           F Stability, Wind Speed 1.5 Meters per Second
Release Rate
(Ibs/min)
1
2
5
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
Distance to Endpoint (miles)
Rural
0.2
0.3
0.5
0.7
0.8
1.0
1.2
1.4
1.5
1.7
1.8
1.9
2.0
2.2
2.6
3.0
3.4
3.7
4.2
4.7
5.2
5.6
Urban
0.1
0.1
0.2
0.3
0.4
0.4
0.5
0.6
0.6
0.7
0.8
0.8
0.9
0.9
1.2
1.3
1.5
1.6
1.9
2.1
2.3
2.5
Release Rate
(Ibs/min)
750
800
900
1,000
1,500
2,000
2,500
3,000
4,000
5,000
6,000
7,000
7,500
8,000
9,000
10,000
15,000
20,000
25,000
30,000
40,000
50,000
Distance to Endpoint (miles)
Rural
5.8
5.9
6.3
6.6
8.1
9.3
10
11
13
14
16
17
18
18
19
20
25
*
*
*
*
*
Urban
2.6
2.7
2.9
3.0
3.8
4.4
4.9
5.4
6.2
7.0
7.6
8.3
8.6
8.9
9.4
9.9
12
14
16
18
20
*
                                                         : More than 25 miles (report distance as 25 miles)
April 15, 1999
                                              5-14

-------
                                       Reference Table 12
                     Distances to Toxic Endpoint for Anhydrous Sulfur Dioxide
                          F Stability, Wind Speed 1.5 Meters per Second
Release Rate
(Ibs/min)
1
2
5
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
Distance to Endpoint (miles)
Rural
0.2
0.2
0.4
0.6
0.7
0.9
1.1
1.3
1.4
1.6
1.8
1.9
2.0
2.1
2.7
3.1
3.6
3.9
4.6
5.2
5.8
6.3
Urban
0.1
0.1
0.2
0.2
0.3
0.4
0.5
0.5
0.6
0.7
0.7
0.8
0.8
0.9
1.1
1.3
1.4
1.6
1.9
2.1
2.3
2.5
Release Rate
(Ibs/min)
750
800
900
1,000
1,500
2,000
2,500
3,000
4,000
5,000
6,000
7,000
7,500
8,000
9,000
10,000
15,000
20,000
25,000
30,000
40,000
50,000
Distance to Endpoint (miles)
Rural
6.6
6.8
7.2
7.7
9.6
11
13
14
17
19
21
23
24
25
*
*
*
*
*
*
*
*
Urban
2.6
2.7
2.9
3.1
3.8
4.5
5.0
5.6
6.5
7.3
8.1
8.8
9.1
9.5
10
11
13
16
18
19
23
*
                                                        : More than 25 miles (report distance as 25 miles)
April 15, 1999
                                              5-15

-------
                                                      Reference Table 13
       Distance to Overpressure of 1.0 psi for Vapor Cloud Explosions of 500 - 2,000,000 Pounds of Regulated Flammable Substances
                                    Based on TNT Equivalent Method, 10 Percent Yield Factor
Quantity in Cloud (pounds)
CAS No.
75-07-0
74-86-2
598-73-2
106-99-0
106-97-8
25167-67-3
590-18-1
624-64-6
106-98-9
107-01-7
463-58-1
7791-21-1
590-21-6
557-98-2
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
Chemical Name
Acetaldehyde
Acetylene
Bromotrifluoroethylene
1,3-Butadiene
Butane
Butene
2-Butene-cis
2-Butene-trans
1 -Butene
2-Butene
Carbon oxysulfide
Chlorine monoxide
1 -Chloropropylene
2-Chloropropylene
Cyanogen
Cyclopropane
Dichlorosilane
Difluoroethane
Dimethylamine
2,2-Dimethylpropane
Ethane
Ethyl acetylene
Ethvlamine
500
2,000
5,000
10,000
20,000
50,000
100,000
200,000
500,000
1,000,000
2,000,000
Distance (Miles) to 1 psi Overpressure
0.05
0.07
0.02
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.04
0.02
0.05
0.05
0.05
0.06
0.04
0.04
0.06
0.06
0.06
0.06
0.06
0.08
0.1
0.04
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.06
0.03
0.08
0.08
0.08
0.1
0.06
0.06
0.09
0.1
0.1
0.1
0.09
0.1
0.1
0.05
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.08
0.04
0.1
0.1
0.1
0.1
0.08
0.09
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.06
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.1
0.05
0.1
0.1
0.1
0.2
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.08
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.1
0.06
0.2
0.2
0.2
0.2
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.1
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.08
0.2
0.2
0.2
0.3
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.4
0.1
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.2
0.1
0.3
0.3
0.3
0.4
0.2
0.2
0.3
0.4
0.4
0.4
0.3
0.4
0.5
0.2
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.3
0.1
0.4
0.4
0.4
0.5
0.3
0.3
0.4
0.5
0.5
0.5
0.4
0.5
0.7
0.2
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.4
0.2
0.5
0.5
0.5
0.6
0.4
0.4
0.6
0.6
0.6
0.6
0.6
0.7
0.8
0.3
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.5
0.2
0.6
0.6
0.6
0.8
0.5
0.5
0.7
0.8
0.8
0.8
0.7
0.8
1.0
0.4
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.6
0.3
0.8
0.8
0.8
1.0
0.6
0.6
0.9
1.0
1.0
1.0
0.9
April 15, 1999
                                                            5-16

-------
                                                         Reference Table 13 (continued)
Quantity in Cloud (pounds)
CAS No.
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
Chemical Name
Ethyl chloride
Ethylene
Ethyl ether
Ethyl mercaptan
Ethyl nitrite
Hydrogen
Isobutane
Isopentane
Isoprene
Isopropylamine
Isopropyl chloride
Methane
Methylamine
3 -Methyl- 1-butene
2-Methyl-l-butene
Methyl ether
Methyl formate
2-Methylpropene
1,3-Pentadiene
Pentane
1-Pentene
2-Pentene, (E)-
2-Pentene, (Z)-
Propadiene
500
2,000
5,000
10,000
20,000
50,000
100,000
200,000
500,000
1,000,000
2,000,000
Distance (Miles) to 1 psi Overpressure
0.05
0.06
0.06
0.05
0.05
0.09
0.06
0.06
0.06
0.06
0.05
0.07
0.06
0.06
0.06
0.05
0.04
0.06
0.06
0.06
0.06
0.06
0.06
0.06
0.08
0.1
0.09
0.09
0.07
0.1
0.1
0.1
0.1
0.09
0.08
0.1
0.09
0.1
0.1
0.09
0.07
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.2
0.2
0.4
0.3
0.3
0.3
0.3
0.2
0.3
0.3
0.3
0.3
0.3
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.4
0.3
0.3
0.3
0.5
0.4
0.4
0.4
0.3
0.3
0.4
0.3
0.4
0.4
0.3
0.3
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.5
0.4
0.4
0.3
0.6
0.5
0.5
0.5
0.4
0.4
0.5
0.4
0.5
0.5
0.4
0.3
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.7
0.6
0.5
0.5
0.9
0.6
0.6
0.6
0.6
0.5
0.7
0.6
0.6
0.6
0.5
0.4
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.8
0.7
0.7
0.6
1.1
0.8
0.8
0.8
0.7
0.6
0.8
0.7
0.8
0.8
0.7
0.6
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.8
1.0
0.9
0.9
0.7
1.4
1.0
1.0
1.0
0.9
0.8
1.0
0.9
1.0
1.0
0.9
0.7
1.0
1.0
1.0
1.0
1.0
1.0
1.0
April 15, 1999
                                                                     5-17

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                                                       Reference Table 13 (continued)
Quantity in Cloud (pounds)
CAS No.
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
Chemical Name
Propane
Propylene
Propyne
Silane
Tetrafluoroethylene
Tetramethylsilane
Trichlorosilane
Trifluorochloroethylene
Trimethylamine
Vinyl acetylene
Vinyl chloride
Vinyl ethyl ether
Vinyl fluoride
Vinylidene chloride
Vinylidene fluoride
Vinyl methyl ether
500
2,000
5,000
10,000
20,000
50,000
100,000
200,000
500,000
1,000,000
2,000,000
Distance (Miles) to 1 psi Overpressure
0.06
0.06
0.06
0.06
0.02
0.06
0.03
0.02
0.06
0.06
0.05
0.06
0.02
0.04
0.04
0.06
0.1
0.1
0.1
0.1
0.03
0.1
0.04
0.03
0.1
0.1
0.08
0.09
0.04
0.06
0.06
0.09
0.1
0.1
0.1
0.1
0.04
0.1
0.06
0.05
0.1
0.1
0.1
0.1
0.05
0.08
0.09
0.1
0.2
0.2
0.2
0.2
0.05
0.2
0.08
0.06
0.2
0.2
0.1
0.2
0.06
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.07
0.2
0.1
0.07
0.2
0.2
0.2
0.2
0.08
0.1
0.1
0.2
0.3
0.3
0.3
0.3
0.09
0.3
0.1
0.1
0.3
0.3
0.2
0.3
0.1
0.2
0.2
0.3
0.4
0.4
0.4
0.4
0.1
0.4
0.2
0.1
0.4
0.4
0.3
0.3
0.1
0.2
0.2
0.3
0.5
0.5
0.5
0.5
0.1
0.5
0.2
0.2
0.4
0.5
0.4
0.4
0.2
0.3
0.3
0.4
0.6
0.6
0.6
0.6
0.2
0.6
0.3
0.2
0.6
0.6
0.5
0.6
0.2
0.4
0.4
0.6
0.8
0.8
0.8
0.8
0.2
0.8
0.4
0.3
0.8
0.8
0.6
0.7
0.3
0.5
0.5
0.7
1.0
1.0
1.0
1.0
0.3
1.0
0.4
0.3
1.0
1.0
0.8
0.9
0.4
0.6
0.6
0.9
April 15, 1999
                                                                  5-18

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        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 substance
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 substance as a representative scenario for all the regulated
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 - chlorine,
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 threshold in several processes or locations, you need only analyze one alternative
scenario for it.

        According to the rule (40 CFR 68.28), alternative scenarios should be more likely to occur than the
worst-case scenario and should reach an endpoint offsite, unless no such scenario exists.  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 should be those that lead to concentrations above
the toxic endpoint beyond your fenceline. Scenarios  for flammable substances should have the potential to
cause substantial damage, including 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 isolation 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 substances used in ammonia refrigeration, chemical
distribution, propane distribution, warehouses, or POTWs, consult EPA's risk management program guidance

April 15, 1999

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Chapter 6
Determining Alternative Release Scenarios
documents for these industry sectors.

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

        •       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 hazards analysis, if you have conducted 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 hazards analysis, you may review your operations 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 choice of alternative release scenarios is somewhat more complicated
than for toxic substances, because the consequences of a release and the endpoint 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 substances include:

        •       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 hazard to anyone in the area of the cloud. 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 explosion also can result. BLEVEs are
                generally considered unlikely events; however, if you think 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                                      6-2

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                                                                                            Chapter 6
                                                                 Determining Alternative Release Scenarios
                calculation methods to estimate effects of vessel fragmentation.  (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 events; however, if conditions 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 substances.
                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 Section 5.2  on flammable mixtures). If the mixture
contains both flammable and non-flammable components, the analysis should be carried out considering 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 liquids 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 substances. Chapters 9 provides
information on calculation release rates for flammable substances.  Chapter 10 describes how to estimate
distances to flammable endpoints.
April 15, 1999

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Chapter 6
Determining Alternative Release Scenarios
                                   This page intentionally left blank.
April 15, 1999                                       6-4

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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 hazards 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 substance.
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, 1999

-------
Chapter 7
Estimation of Release Rates for Alternative Scenarios for Toxic Substances
                                    QR  = HA  x pf
                                              x  GF
                                                                                (7-1)
where:
QR
HA
                Tt

                GF
Release rate (pounds per minute)
Hole or puncture area (square inches) (from hazard evaluation or best
estimate)
Tank pressure (pounds per square inch absolute (psia)) (from process
information; for liquefied gases, equilibrium vapor pressure at 25 °C is
included in Exhibit B-l, Appendix B)
Tank temperature (K), where K is absolute temperature in kelvins; 25 °C
(77 °F) is 298 K
Gas Factor, incorporating discharge coefficient, ratio of specific heats,
molecular weight, and conversion factors (listed for each regulated toxic gas
in Exhibit B-l, Appendix B)
        You can estimate the hole area from the size and shape of the hole.  For a circular hole, you would
use the formula for the area of a circle (area = Tir2, where n 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 1A inches in
      diameter in the tank wall. You estimate the area from the formula for area of a circle (itr2, where r is the
      radius). The radius of the hole is 1 1/4 inches, so the area is it x (1  1/4)2, or 5 square inches.  From Exhibit
      B-l, the Gas Factor for diborane is 17. Therefore, the release rate, from Equation 7-1, is:

                      QR = 5 x  30 x l/(298)'/2 x 17 = 148 pounds 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 carry out the estimation of
distance as discussed in Chapter 8.
April 15, 1999
                                                  7-2

-------
                                                                                             Chapter 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 fraction of the liquefied gas and
possibly aerosolization (two-phase release).  It is complex to determine which type of release (i.e., gas, two-
phase) 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-l, Appendix B,
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 carry 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.
Exhibit B-l 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
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):
                          QR  = HA  x 6.82
LH +       x  Pg                   (7.2)
                 g                   ^   '
                                                 DF2            DF
April 15, 1999                                       1 -'.

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Chapter 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 evaluation 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 pounds per cubic foot)
                LH     =      Height of liquid column above hole (inches) (from hazard evaluation or best
                               estimate)
                Pg      =      Gauge pressure of the tank pressure (pounds per square inch gauge (psig),
                               from vapor pressure of gas (listed in Exhibit B-l, 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 immediately 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 substantiate,  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 deinventory),
and water/chemical sprays. These mitigation techniques have the effect of reducing either the release rate or
the duration of the release, or both.
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                                       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  substantiate the time it will 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 fractional reduction of the release rate by the mitigation
technique. Apply this fraction 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:
                                       QRR  =  (1  -  FK) x  QR
                                                                                 (7-3)
where:
QRR
FR
QR
Reduced release rate (pounds per minute)
Fractional reduction resulting from mitigation
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 pounds 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:

           QRR    = (1 - 0.9) x (660 pounds 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
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Chapter 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,
                              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.
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                                                                                            Chapter 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.)
                                    QRL = HA x   lH  x LLF                             (7-4)
where:          QRL    =      Liquid release rate (pounds per minute)
                HA    =      Hole or puncture area (square inches) (from hazard evaluation or best
                               estimate)
                LH    =      Height of liquid column above hole (inches) (from hazard evaluation 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 equation 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 would 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.

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Chapter 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 pounds 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:

                   QRL = 5 x  (23)'/2 x 41 = 983 pounds per minute

   It takes 10 minutes to stop the release, so 10 minutes x 983 pounds per minute = 9,830 pounds 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 liquid 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 substance
through the pipe using the initial operational flow rate as follows:

                                      „      FR  x DF x  0.033

                                       •=                                                     <7-5)
where:          Va      =       Initial operational flow velocity (feet per minute)
                FR     =       Initial operational flow rate (pounds per minute)
                DF     =       Density Factor (from Exhibit B-2, Appendix B)
                Ap      =       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
of the pipe) using the formula for the area of a circle (area = Tir2, where r is the radius).

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


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                                                                                              Chapter 7
                                      Estimation of Release Rates for Alternative Scenarios for Toxic Substances
acceleration or deceleration 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:

  Vb  =197  x ^[28.4 x  (PT  - 14.7)  x DF\ +  [5.97 x  (Zfl - Z6)]  + [2.58xlQ-5  x F/] (?_6)
where:          Vb      =       Release velocity (feet per minute)
                PT      =       Total pressure on liquid in pipe (psia)
                DF     =       Density factor, see Exhibit B-1 or Exhibit B-2
                Za      =       Height of pipeline at inlet (feet)
                Zb      =       Height of pipeline at break (feet)
                Va      =       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 Za-Zb is
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  x A
                                        QRL =  	*	P—                                 (7-7)
                                           L    DF x 0.033                                 v    '
where:          QRL    =       Release rate (pounds per minute)
                Vb      =       Release velocity (feet per minute)
                DF     =       Density Factor
                Ap      =       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 (QRL) from the equation above by the time (in minutes) that likely would be needed to stop the
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 substantiate 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 deemed considerable, an
established method for calculating frictional head loss such as the Darcy formula may be used.
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Chapter 7
Estimation of Release Rates for Alternative Scenarios for Toxic Substances
                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 Reduce Quantity Released

        Examples of mitigation techniques to reduce the quantity released into the pool include automatic
shutoff valves and emergency deinventory.  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 pounds.
                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.
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                                                                                            Chapter 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
Appendix D, Section D.2.2 for the derivation of these factors). If your ambient temperature is between 25 °C
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 (LFB) and DF from Exhibit B-l.  Calculate the
release rate from the following equation for liquids at ambient temperature with no mitigation:

                                  QR  =  QS x 2.4 x LFA  x DF                           (7-8)


where:          QR     =      Release rate (pounds per minute)
                QS     =      Quantity released (pounds)
                2.4     =      Wind speed factor  = 3.0078, 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 pounds 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 x 2.4 x  0.0046 x 0.58 = 63 pounds per minute
        Elevated temperature. For pools with no mitigation, if the liquid is at an elevated temperature (above
50 °C or at or close to its boiling point), find the Liquid Factor Boiling (LFB) 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
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
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 x 2.4 x LFB x  DF                            (7-9)
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Chapter 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 = 3.0078, 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 (LFB), if
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  x LFA  x A                              (7-10)


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

                                      QR = 2.4  x LFB  x A                              (7-11)


where:          QR     =       Release rate (pounds per minute)
                2.4     =       Wind speed factor = 3.0078, 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.

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                                                                                             Chapter 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 fractional reduction of the release rate
by the mitigation technique. Apply this fraction to the release rate (evaporation rate from the pool) that
would have occurred without the mitigation technique, as follows:

                                       QRRV=  (l-FR)  x QR                               (7.12)

where:          Q^RV  =      Reduced evaporation rate (release rate to air) from pool (pounds per
                               minute)
                FR     =      Fractional reduction resulting from mitigation
                QR     =      Evaporation rate from pool without mitigation (pounds per minute)

                       Temperature Corrections for Liquids at Temperatures between 25 and 50 °C

        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 (TCP) from Exhibit B-4, Appendix B, to calculate a corrected
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 TCP 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  paragraph, estimate a liquid 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
above 25 °C, use the corrected release rate to estimate the duration.
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Chapter 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 substance or oleum that may be spilled 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 carrying 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 solution as a release of the pure substance. 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.
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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 substances, 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. The
generic tables and the conditions for which each table is applicable are described in Exhibit 4. Four chemical-
specific 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 substances other than ammonia, 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, 1999

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Chapter 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
Gas or Vapor Density
Neutrally buoyant
Dense
Topography
Rural
Urban
Rural
Urban
Release Duration
(minutes)
10
60
10
60
10
60
10
60
Reference Table
Number
14
15
16
17
18
19
20
21
                                              Exhibit 5
              Chemical-Specific Reference Tables of Distances for Alternative Scenarios
Substance
Anhydrous ammonia
liquefied under pressure
Non-liquefied ammonia,
ammonia liquefied by
refrigeration, or aqueous
ammonia
Chlorine
Sulfur dioxide (anhydrous)
Conditions of Release
Gas or Vapor
Density
Dense
Neutrally buoyant
Dense
Dense
Release Duration
(minutes)
10-60
10-60
10-60
10-60
Topography
Rural, urban
Rural, urban
Rural, urban
Rural, urban
Reference
Table
Number
22
23
24
25
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                                                                                            Chapter 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 Substances Other than Ammonia, Chlorine, and Sulfur Dioxide

        •       Find the toxic endpoint for the substance in Appendix 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 obstructions.

                       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).
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Chapter 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 substance
                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 substance by reading across the top of
                       the table. If the endpoint of the  substance 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 substance 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 substance.

        For Ammonia, Chlorine, or Sulfur Dioxide

        •       Find the appropriate chemical-specific table for  your substance (see the descriptions 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
                       obstructions.

                       Use the urban column if your site is in an urban or obstructed 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                                       8-4

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                                                                                              Chapter 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
DA.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
DAS. 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 pounds per minute of chlorine from a tank. A chemical-
   specific 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 pounds 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
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Chapter 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 pounds; 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

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        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 carrying 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 (Tt, absolute temperature, Kelvin) is 282 K,
   9°C, and the square root of the temperature is 16.8.  The pressure in the tank (Pt) is approximately 728 pounds
   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 x 728 x (1/16.8) x 18 = 3,900 pounds 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.
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Chapter 9
Estimation of Release Rates for Alternative Scenarios for Flammable Substances	

                Gases Liquefied by Refrigeration

        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 LFB) for liquids 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

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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  separately by release duration (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 substance in Appendix 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.
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Chapter 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 obstructions.

                       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
Gas or Vapor Density
Neutrally buoyant
Dense
Topography
Rural
Urban
Rural
Urban
Release Duration
(minutes)
10-60
10-60
10-60
10-60
Reference Table
Number
26
27
28
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 substance
                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 substance by reading across the top of the table.
                       If the LFL of the substance 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 substance at the left
                       of the table.  If the calculated release rate is halfway between two values on the
April 15, 1999
                                                10-2

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                                                                                                 Chapter 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 substance.
   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 pounds 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
                                                   10-3

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Chapter 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 pounds 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:

                            QRL     =        3.1x4.9x34
                                     =        520 pounds per minute

   You estimate that the release of the liquid could be stopped in about 10 minutes. In 10 minutes, 10 x 520, or
   5,200 pounds, 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     =        5,200x2.4x0.11x0.69
                                     =        950 pounds 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 pounds 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 pounds per
   minute, which is higher than  the evaporation rate estimated for the pool of ethyl  ether.  For a release rate less
   than 1,500 pounds per minute, the distance to the LFL is less than 0.1 miles.
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                                                                                          Chapter 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 receive second degree burns
from a 40-second exposure.  The heat radiation endpoint for this analysis is 5 kilowatts per square meter
(kW/m2).  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 pool, in square feet,
that might be formed by the release of a flammable substance. 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 pool of the maximum size, particularly for liquefied gases.

        Distances may be estimated from the  PFF and the pool area as follows:

                                          d = PFF x  JA                                  (10-1)

where:         d       =       Distance (feet)
               PFF   =       Pool Fire Factor (listed for each flammable substance in Appendix C,
                               Exhibits C-2 and C-3)
               A       =       Pool area (square feet)
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Chapter 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 pounds of ethyl ether, you want to estimate the consequences of a pool fire. You
   estimate that 15,000 pounds 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 x 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/m2. 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,
   Appendix C, PFF for ethyl ether is 4.3. From Equation 10-1, the distance (d) to 5 kW/m2 is:

                                d = 4.3  x 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 substance released is in the vapor cloud, you may estimate a smaller
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                                                                                           Chapter 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 fraction factor" (FFF), listed in Appendix C,
Exhibit C-2 for regulated flammable gases, to estimate the quantity that could be immediately flashed into
vapor upon release. A factor of two is included to estimate the quantity that might be carried along as spray
or aerosol. See Appendix D, Section D. 11 for the derivation of this equation. The equation is:

                                       QF = FFF  x QS x 2                               (10-2)

where:          QF    =       Quantity flashed into vapor plus aerosol (pounds) (cannot be larger than
                               QS)
                FFF   =       Flash fraction  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

        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 fraction 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-l 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                                      10-7

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Chapter 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 pounds 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 pounds).  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 x 50,000 x 2 = 38,000 pounds

   You assume 38,000 pounds of propane is in the flammable part of the vapor cloud.  This quantity falls between
   20,000 pounds and 50,000 pounds in Reference Table 13; 50,000 pounds is the quantity closest to your
   quantity.  From the table, the distance to 1 psi overpressure is 0.3 mile for 50,000 pounds 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

-------
                                      Reference Table 14
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        10-Minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-64
64-510
510-1,300
1,300-2,300
2,300-4,100
4,100-6,300
6,300 - 8,800
8,800 - 12,000
12,000 - 16,000
16,000- 19,000
19,000-22,000
22,000 - 26,000
26,000 - 30,000
30,000 - 36,000
36,000 - 42,000
42,000 - 47,000
47,000 - 54,000
54,000 - 60,000
60,000 - 70,000
70,000 - 78,000
78,000 - 87,000
87,000 - 97,000
97,000-110,000
110,000- 120,000
120,000-130,000
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
130,000-140,000
140,000 - 160,000
160,000-180,000
180,000- 190,000
190,000-210,000
210,000-220,000
220,000 - 240,000
240,000-261,000
261,000-325,000
325,000 - 397,000
397,000 - 477,000
477,000 - 566,000
566,000 - 663,000
663,000 - 769,000
769,000-1,010,000
1,010,000- 1,280,000
1,280,000-1,600,000
1,600,000- 1,950,000
1,950,000-2,340,000
2,340,000 - 2,770,000
2,770,000 - 3,240,000
3,240,000 - 4,590,000
4,590,000-6,190,000
>6, 190,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                            10-9

-------
                                      Reference Table 15
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        60-Minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-79
79-630
630-1,600
1,600-2,800
2,800 - 5,200
5,200 - 7,900
7,900-11,000
11,000- 14,000
14,000-19,000
19,000-23,000
23,000 - 27,000
27,000 - 32,000
32,000 - 36,000
36,000 - 42,000
42,000 - 47,000
47,000 - 52,000
52,000 - 57,000
57,000-61,000
61,000-68,000
68,000 - 73,000
73,000 - 79,000
79,000 - 84,000
84,000-91,000
91,000-97,000
97,000 - 100,000
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
100,000 - 108,000
108,000- 113,000
113,000-120,000
120,000 - 126,000
126,000-132,000
132,000- 140,000
140,000-150,000
150,000- 151,000
151,000-171,000
171,000- 191,000
191,000-212,000
212,000-233,000
233,000 - 256,000
256,000 - 280,000
280,000 - 332,000
332,000 - 390,000
390,000 - 456,000
456,000 - 529,000
529,000-610,000
610,000-699,000
699,000 - 796,000
796,000- 1,080,000
1,080,000-1,410,000
>1,410,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                            10- 10

-------
                                      Reference Table 16
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        10-Minute Release, Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-160
160- 1,400
1,400-3,600
3,600 - 6,900
6,900-13,000
13,000-22,000
22,000-31,000
31,000-42,000
42,000 - 59,000
59,000 - 73,000
73,000 - 88,000
88,000 - 100,000
100,000 - 120,000
120,000- 150,000
150,000-170,000
170,000-200,000
200,000 - 230,000
230,000 - 260,000
260,000-310,000
310,000-340,000
340,000 - 390,000
390,000 - 430,000
430,000 - 490,000
490,000 - 540,000
540,000 - 600,000
Distance to Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
600,000 - 660,000
660,000 - 720,000
720,000 - 810,000
810,000 - 880,000
880,000 - 950,000
950,000- 1,000,000
1,000,000-1,100,000
1,100,000- 1,220,000
1,220,000-1,530,000
1,530,000- 1,880,000
1,880,000-2,280,000
2,280,000-2,710,000
2,710,000-3,200,000
3,200,000 - 3,730,000
3,730,000 - 4,920,000
4,920,000-6,310,000
6,310,000-7,890,000
7,890,000 - 9,660,000
9,660,000-11,600,000
11,600,000- 13,800,000
13,800,000-16,200,000
16,200,000-23,100,000
23,100,000-31,300,000
>3 1,300,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                            10- 11

-------
                                      Reference Table 17
     Neutrally Buoyant Plume Distances to Toxic Endpoint for Release Rate Divided by Endpoint
        60-Minute Release, Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
0-200
200- 1,700
1,700-4,500
4,500 - 8,600
8,600 - 17,000
17,000-27,000
27,000 - 39,000
39,000 - 53,000
53,000 - 73,000
73,000 - 90,000
90,000-110,000
110,000- 130,000
130,000-150,000
150,000- 170,000
170,000-200,000
200,000 - 220,000
220,000 - 240,000
240,000 - 270,000
270,000 - 300,000
300,000 - 320,000
320,000 - 350,000
350,000 - 370,000
370,000-410,000
410,000-430,000
430,000 - 460,000
Distance to
Endpoint
(miles)
0.1
0.2
0.3
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
460,000 - 490,000
490,000 - 520,000
520,000 - 550,000
550,000 - 580,000
580,000-610,000
610,000-640,000
640,000 - 680,000
680,000 - 705,000
705,000 - 804,000
804,000 - 905,000
905,000-1,010,000
1,010,000- 1,120,000
1,120,000-1,230,000
1,230,000- 1,350,000
1,350,000-1,620,000
1,620,000- 1,920,000
1,920,000-2,250,000
2,250,000 - 2,620,000
2,620,000 - 3,030,000
3,030,000 - 3,490,000
3,490,000 - 3,980,000
3,980,000 - 5,410,000
5,410,000-7,120,000
>7, 120,000
Distance to
Endpoint
(miles)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
6.2
6.8
7.5
8.1
8.7
9.3
9.9
11
12
14
15
16
17
19
22
25
>25*
                                                                       *Report distance as 25 miles
April 15, 1999
                                            10- 12

-------
                                                           Reference Table 18
                                                  Dense Gas Distances to Toxic Endpoint
                             10-minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (mg/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
0.6
0.9
1.4
2.0
3.7
5.0
7.4
8.7
12
17
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.4
0.6
1.1
1.5
2.7
3.7
5.3
6.8
8.7
13
16
19
23
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
0.4
0.5
0.9
1.2
2.2
3.0
4.3
5.5
7.4
11
13
16
19
22
25
>25
*
*
*
*
*
*
*
*
*
*
*
0.2
0.4
0.6
0.9
1.5
2.1
3.0
3.8
5.0
7.4
9.3
11
13
15
17
19
22
>25
*
*
*
*
*
*
*
*
*
0.2
0.3
0.4
0.6
1.1
1.9
2.3
2.8
3.7
5.3
6.8
8.1
9.9
12
13
14
17
19
24
>25
*
*
*
*
*
*
*
0.1
0.2
0.4
0.5
0.9
1.2
1.7
2.3
3.0
4.5
5.6
6.8
8.1
9.3
11
12
14
16
19
22
>25
*
*
*
*
*
*
0.1
0.2
0.3
0.4
0.7
1.0
1.4
1.9
2.4
3.6
4.5
5.2
6.8
7.4
8.7
9.3
11
12
16
18
22
>25
*
*
*
*
*
0.1
0.1
0.2
0.4
0.7
0.9
1.2
1.6
2.1
3.0
3.8
4.5
5.6
6.8
7.4
8.1
9.3
11
13
16
19
22
>25
*
*
*
*
<0.1
0.1
0.2
0.2
0.5
0.6
0.9
1.1
1.4
2.1
2.7
3.1
3.9
4.5
5.2
5.7
6.8
7.4
9.3
11
13
16
24
>25
*
*
*
<0.1
0.1
0.1
0.2
0.3
0.4
0.6
0.8
1.1
1.6
1.9
2.3
2.9
3.4
3.8
4.2
4.9
5.6
6.8
8.1
9.9
11
18
22
>25
*
*
#
<0.1
0.1
0.1
0.3
0.4
0.6
0.7
0.9
1.3
1.6
2.2
2.4
2.7
3.2
3.5
4.1
4.7
5.8
6.8
8.1
9.3
15
18
21
>25
*
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.6
0.7
1.1
1.3
1.5
1.9
2.2
2.5
2.8
3.3
3.7
4.7
5.3
6.8
7.4
12
15
17
20
23
#
#
<0.1
0.1
0.2
0.2
0.4
0.5
0.5
0.9
1.1
1.3
1.6
1.9
2.1
2.4
2.8
3.1
4.0
4.6
5.7
6.8
10
13
14
17
19
#
#
#
<0.1
0.1
0.2
0.2
0.3
0.4
0.6
0.7
0.8
1.0
1.2
1.3
1.4
1.7
2.1
2.4
2.8
3.5
4.0
6.5
7.8
8.9
11
12
#
#
#
<0.1
0.1
0.1
0.2
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.3
1.6
1.9
2.4
2.8
4.5
5.4
6.3
7.4
8.5
#
#
#
#
<0.1
0.1
0.1
0.2
0.2
0.3
0.4
0.4
0.6
0.6
0.7
0.8
0.9
1.1
1.3
1.5
1.9
2.2
3.6
4.4
5.0
6.0
6.8
> 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                                 10- 13

-------
                                                       Reference Table 19
                                             Dense Gas Distances to Toxic Endpoint
                        60-minute Release, Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (nig/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
0.5
0.8
1.6
2.0
4.0
5.5
8.7
12
17
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.4
0.6
1.0
1.4
2.8
3.9
6.1
8.1
11
19
25
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.3
0.5
0.8
1.2
2.2
3.1
4.8
6.2
8.7
14
19
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.2
0.3
0.5
0.8
1.5
2.1
3.2
4.1
5.6
9.3
12
15
20
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
0.2
0.2
0.4
0.6
1.1
1.5
2.2
2.9
4.0
6.2
8.7
11
14
17
19
22
>25
*
*
*
*
*
*
*
*
*
*
0.1
0.2
0.3
0.5
0.9
1.2
1.8
2.3
3.2
5.0
6.8
8.1
11
13
15
17
21
25
>25
*
*
*
*
*
*
*
*
0.1
0.2
0.2
0.4
0.7
1.0
1.4
1.8
2.5
3.9
5.1
6.1
8.1
9.9
12
13
16
19
25
>25
*
*
*
*
*
*
*
0.1
0.1
0.2
0.3
0.6
0.8
1.2
1.6
2.1
3.3
4.2
5.2
6.8
8.1
9.3
11
14
16
20
25
>25
*
*
*
*
*
*
<0.1
0.1
0.2
0.2
0.4
0.6
0.8
1.1
1.4
2.2
2.8
3.4
4.3
5.2
6.0
6.8
8.7
9.9
13
16
21
25
>25
*
*
*
*
#
<0.1
0.1
0.2
0.3
0.4
0.6
0.7
1.1
1.6
2.0
2.4
3.0
3.7
4.3
4.8
5.8
6.8
9.3
11
14
17
>25
*
*
*
*
#
<0.1
0.1
0.1
0.2
0.3
0.5
0.6
0.9
1.3
1.6
1.9
2.5
2.9
3.4
3.8
4.7
5.3
6.8
8.7
11
14
25
>25
*
*
*
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.7
1.0
1.3
1.5
1.9
2.3
2.7
3.0
3.6
4.1
5.4
6.8
8.7
11
19
25
>25
*
*
#
#
<0.1
0.1
0.2
0.2
0.3
0.4
0.6
0.9
1.1
1.3
1.7
1.9
2.2
2.5
3.0
3.5
4.5
5.4
7.4
8.7
16
20
24
>25
*
#
#
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1.0
1.2
1.3
1.5
1.7
2.0
2.6
3.1
4.0
4.8
8.8
11
14
17
20
#
#
#
<0.1
0.1
0.1
0.1
0.2
0.2
0.4
0.4
0.5
0.7
0.7
0.9
1.0
1.2
1.4
1.7
2.1
2.6
3.1
5.6
7.3
9.4
11
13
#
#
#
#
<0.1
0.1
0.1
0.1
0.2
0.3
0.4
0.4
0.5
0.6
0.7
0.8
0.9
1.1
1.4
1.6
2.1
2.5
4.3
5.6
6.8
8.7
10
> 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                             10- 14

-------
                                                      Reference Table 20
                                             Dense Gas Distances to Toxic Endpoint
                        10-minute Release, Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (nig/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
0.5
0.7
1.1
2.1
3.0
4.1
5.8
7.4
9.9
14
17
20
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.3
0.5
0.8
1.2
2.2
3.0
4.3
5.5
7.4
11
13
15
19
22
24
>25
*
*
*
*
*
*
*
*
*
*
*
0.2
0.4
0.6
1.0
1.9
2.5
3.5
4.5
5.8
8.7
11
12
16
18
20
22
>25
*
*
*
*
*
*
*
*
*
*
0.2
0.3
0.5
0.7
1.2
1.6
2.7
3.1
4.1
5.9
7.4
8.7
11
12
14
16
18
20
>25
*
*
*
*
*
*
*
*
0.1
0.2
0.3
0.5
0.9
1.2
1.8
2.2
3.0
4.3
5.5
6.2
8.1
9.3
11
11
14
15
19
22
>25
*
*
*
*
*
*
0.1
0.2
0.3
0.4
0.8
1.0
1.4
1.9
2.5
3.6
4.5
5.3
6.2
7.4
8.7
9.3
11
12
16
18
22
>25
*
*
*
*
*
0.1
0.1
0.2
0.3
0.6
0.8
1.2
1.4
2.0
2.9
3.6
4.3
5.2
6.2
6.8
7.4
8.7
9.9
12
14
18
20
>25
*
*
*
*
0.1
0.1
0.2
0.3
0.6
0.7
1.0
1.2
1.7
2.5
3.1
3.5
4.5
5.2
6.0
6.8
7.4
8.7
11
12
16
18
>25
*
*
*
*
<0.1
0.1
0.1
0.2
0.4
0.5
0.7
0.9
1.1
1.7
2.1
2.5
3.0
3.7
3.8
4.5
5.3
5.8
7.4
8.7
11
12
20
25
>25
*
*
#
<0.1
0.1
0.1
0.3
0.3
0.6
0.7
0.9
1.2
1.6
1.8
2.2
2.7
3.0
3.3
4.0
4.4
5.5
6.2
8.1
9.3
15
18
21
>25
*
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.6
0.7
1.0
1.2
1.5
1.8
2.2
2.2
2.7
3.2
3.6
4.5
5.2
6.8
7.4
12
15
17
21
24
#
#
<0.1
0.1
0.2
0.2
0.4
0.4
0.6
0.8
1.0
1.2
1.5
1.7
1.9
2.1
2.6
2.9
3.6
4.2
5.2
6.0
9.7
12
14
17
19
#
#
<0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.7
0.9
1.0
1.2
1.4
1.7
1.9
2.1
2.4
3.0
3.6
4.4
5.2
8.3
10
12
14
16
#
#
#
<0.1
0.1
0.1
0.2
0.2
0.3
0.4
0.5
0.6
0.7
0.9
1.0
1.1
1.2
1.4
1.8
2.1
2.6
3.0
5.0
6.1
7.0
8.5
9.7
#
#
#
#
<0.1
0.1
0.1
0.2
0.2
0.3
0.4
0.4
0.5
0.6
0.7
0.7
0.9
0.9
1.2
1.4
1.7
2.0
3.3
4.1
4.7
5.7
6.5
#
#
#
#
#
<0.1
0.1
0.1
0.1
0.2
0.3
0.3
0.4
0.5
0.6
0.6
0.7
0.7
0.9
1.1
1.3
1.6
2.6
3.1
3.7
4.5
5.1
> 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                             10- 15

-------
                                                      Reference Table 21
                                             Dense Gas Distances to Toxic Endpoint
                        60-minute Release, Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release
Rate
(Ibs/mln)
1
2
5
10
30
50
100
150
250
500
750
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
50,000
75,000
100,000
150,000
200,000
Toxic Endpoint (nig/L)
0.0004
0.0007
0.001
0.002
0.0035
0.005
0.0075
0.01
0.02
0.035
0.05
0.075
0.1
0.25
0.5
0.75
Distance (Miles)
0.4
0.7
1.1
1.7
3.3
4.7
7.4
9.9
14
22
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.3
0.5
0.8
1.2
2.4
3.3
5.2
6.8
9.3
16
20
24
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.2
0.4
0.7
1.0
1.9
2.6
4.1
5.3
7.4
12
16
19
>25
*
*
*
*
*
*
*
*
*
*
*
*
*
*
0.2
0.2
0.4
0.7
1.3
1.7
2.7
3.4
4.7
7.4
9.9
12
16
19
23
>25
*
*
*
*
*
*
*
*
*
*
*
0.1
0.2
0.3
0.5
0.9
1.2
1.9
2.4
3.4
5.2
6.8
8.1
11
14
16
18
22
>25
*
*
*
*
*
*
*
*
*
0.1
0.2
0.2
0.4
0.7
1.0
1.5
1.9
2.7
4.2
5.4
6.8
8.7
11
12
14
17
20
25
>25
*
*
*
*
*
*
*
0.1
0.1
0.2
0.3
0.6
0.8
1.2
1.5
2.1
3.2
4.2
5.0
6.8
8.1
9.3
11
13
16
20
24
>25
*
*
*
*
*
*
<0.1
0.1
0.2
0.3
0.5
0.7
1.0
1.3
1.7
2.7
3.5
4.2
5.5
6.8
7.4
8.7
11
12
17
20
>25
*
*
*
*
*
*
#
<0.1
0.1
0.2
0.3
0.4
0.7
0.9
1.1
1.7
2.2
2.7
3.5
4.2
4.9
5.5
6.8
8.1
11
13
17
20
>25
*
*
*
*
#
<0.1
0.1
0.1
0.2
0.3
0.5
0.6
0.8
1.2
1.6
1.8
1.9
3.0
3.4
3.8
4.7
5.3
6.8
8.7
11
14
>25
*
*
*
*
#
#
<0.1
0.1
0.2
0.3
0.4
0.5
0.7
1.0
1.3
1.6
2.0
2.2
2.7
3.0
3.1
4.3
5.6
6.8
8.7
11
20
>25
*
*
*
#
#
<0.1
0.1
0.2
0.2
0.3
0.4
0.5
0.8
1.0
1.2
1.6
1.9
2.1
2.4
2.8
3.3
4.3
5.2
6.8
8.1
15
20
24
>25
*
#
#
<0.1
0.1
0.1
0.2
0.3
0.3
0.4
0.7
0.9
1.0
1.3
1.6
1.7
2.0
2.4
2.7
3.5
4.3
5.6
6.8
13
16
20
>25
*
#
#
#
<0.1
0.1
0.1
0.2
0.2
0.3
0.4
0.5
0.6
0.7
0.9
1.0
1.1
1.3
1.5
2.0
2.4
3.0
3.6
6.6
8.7
10
14
16
#
#
#
#
<0.1
0.1
0.1
0.1
0.2
0.2
0.3
0.4
0.5
0.6
0.6
0.7
0.9
1.0
1.2
1.5
1.9
2.3
4.0
5.3
6.3
8.2
9.9
#
#
#
#
#
<0.1
0.1
0.1
0.1
0.2
0.3
0.3
0.4
0.4
0.5
0.6
0.7
0.7
0.9
1.1
1.5
1.7
3.1
3.9
4.7
6.1
7.3
> 25 miles (report distance as 25 miles)
# <0.1 mile (report distance as 0.1 mile)
                                                             10- 16

-------
                                      Reference Table 22
          Distances to Toxic Endpoint for Anhydrous Ammonia Liquefied Under Pressure
                          D Stability, Wind Speed 3.0 Meters per Second
Release Rate
(Ibs/min)
<10
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
750
800
Distance to Endpoint (miles)
Rural
<0.1*
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.4
0.4
0.5
0.5
0.5
0.5
Urban
0.1*
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
Release Rate
(Ibs/min)
900
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
25,000
30,000
40,000
50,000
75,000
100,000
150,000
200,000
250,000
Distance to Endpoint (miles)
Rural
0.6
0.6
0.7
0.8
0.9
1.0
1.2
1.3
1.6
1.8
2.2
2.5
2.8
3.1
3.5
3.9
4.8
5.4
6.6
7.6
8.4
Urban
0.2
0.2
0.3
0.3
0.3
0.4
0.4
0.5
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.4
1.6
1.9
2.1
2.3
* Report distance as 0.1 mile
April 15, 1999
                                            10-17

-------
                                      Reference 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
(Ibs/min)
<8
8
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
750
Distance to Endpoint (miles)
Rural
0.1*
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.4
0.4
0.4
0.5
0.6
0.6
0.6
Urban
O.I*
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
Release Rate
(Ibs/min)
800
900
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
25,000
30,000
40,000
50,000
75,000
100,000
150,000
200,000
Distance to Endpoint (miles)
Rural
0.7
0.7
0.8
1.0
1.2
1.2
1.5
1.8
2.0
2.2
2.5
3.1
3.6
4.1
4.4
5.1
5.8
7.1
8.2
10
12
Urban
0.2
0.3
0.3
0.4
0.4
0.4
0.5
0.6
0.7
0.7
0.8
1.0
1.2
1.3
1.4
1.6
1.8
2.2
2.5
3.1
3.5
* Report distance as 0.1 mile
April 15, 1999
                                            10-18

-------
                                       Reference Table 24
                             Distances to Toxic Endpoint for Chlorine
                          D Stability, Wind Speed 3.0 Meters per Second
Release Rate
(Ibs/min)
1
2
5
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
Distance to Endpoint (miles)
Rural
<0.1*
0.1
0.1
0.2
0.2
0.2
0.3
0.3
0.3
0.4
0.4
0.4
0.4
0.5
0.6
0.6
0.7
0.8
0.8
1.0
1.0
1.1
Urban
0.1*
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.4
0.4
0.4
0.4
Release Rate
(Ibs/min)
750
800
900
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
25,000
30,000
40,000
50,000
75,000
100,000
150,000
200,000
Distance to Endpoint (miles)
Rural
1.2
1.2
1.2
1.3
1.6
1.8
2.0
2.2
2.5
2.8
3.4
3.9
4.6
5.3
5.9
6.4
7.3
8.1
9.8
11
13
15
Urban
0.4
0.5
0.5
0.5
0.6
0.6
0.7
0.8
0.8
0.9
1.2
1.3
1.6
1.8
2.0
2.1
2.4
2.7
3.2
3.6
4.2
4.8
* Report distance as 0.1 mile
April 15, 1999
                                             10-19

-------
                                       Reference Table 25
                          Distances to Toxic Endpoint for Sulfur Dioxide
                          D Stability, Wind Speed 3.0 Meters per Second
Release Rate
(Ibs/min)
1
2
5
10
15
20
30
40
50
60
70
80
90
100
150
200
250
300
400
500
600
700
Distance to Endpoint (miles)
Rural
0.1*
0.1
0.1
0.2
0.2
0.2
0.2
0.3
0.3
0.4
0.4
0.4
0.4
0.5
0.6
0.6
0.7
0.8
0.9
1.0
1.1
1.2
Urban
0.1*
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.4
0.4
0.4
0.4
Release Rate
(Ibs/min)
750
800
900
1,000
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
15,000
20,000
25,000
30,000
40,000
50,000
75,000
100,000
150,000
200,000
Distance to Endpoint (miles)
Rural
1.3
1.3
1.4
1.5
1.9
2.2
2.3
2.7
3.1
3.3
4.0
4.6
5.6
6.5
7.3
8.0
9.2
10
13
14
18
20
Urban
0.5
0.5
0.5
0.5
0.6
0.7
0.8
0.8
1.0
1.1
1.3
1.4
1.7
1.9
2.1
2.3
2.6
2.9
3.5
4.0
4.7
5.4
 : Report distance as 0.1 mile
April 15, 1999
                                              10-20

-------
                                    Reference Table 26
             Neutrally Buoyant Plume Distances to Lower Flammability 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)]
0-28
28-40
40-60
60 - 220
220 - 530
530-860
860 - 1,300
1,300 - 1,700
1,700 - 2,200
2,200 - 2,700
Distance to
Endpoint
(miles)
0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
2,700 - 3,300
3,300 - 3,900
3,900 - 4,500
4,500 - 5,200
5,200 - 5,800
5,800 - 6,800
6,800 - 8,200
8,200 - 9,700
9,700- 11,000
11,000- 13,000
Distance to
Endpoint
(miles)
0.9
1.0
1.1
1.2
1.3
1.4
1.6
1.8
2.0
2.2
                                    Reference Table 27
             Neutrally Buoyant Plume Distances to Lower Flammability 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)]
0-68
68 - 100
100- 150
150-710
710- 1,500
1,500 - 2,600
2,600 - 4,000
4,000 - 5,500
Distance to
Endpoint
(miles)
0.1
0.1
0.1
0.2
0.3
0.4
0.5
0.6
Release Rate/Endpoint
[(lbs/min)/(mg/L)]
5,500 - 7,300
7,300 - 9,200
9,200- 11,000
11,000- 14,000
14,000- 18,000
18,000-26,000
26,000-31,000
31,000-38,000
Distance to
Endpoint
(miles)
0.7
0.8
0.9
1.0
1.2
1.4
1.6
1.8
April 15, 1999
                                          10-21

-------
                                                        Reference Table 28
                                          Dense Gas Distances to Lower Flammability Limit
                                   Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release
Rate
(Ibs/min)
<1,500
1,500
2,000
2,500
3,000
4,000
5,000
7,500
10,000
Lower Flammability Limit (mg/L)
27
30
35
40
45
50
60
70
100
>100
Distance (Miles)
#
<0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.2
#
<0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
#
#
<0.1
0.1
0.1
0.1
0.1
0.1
0.1
#
#
#
<0.1
0.1
0.1
0.1
0.1
0.1
#
#
#
#
<0.1
0.1
0.1
0.1
0.1
#
#
#
#
<0.1
0.1
0.1
0.1
0.1
#
#
#
#
#
<0.1
0.1
0.1
0.1
#
#
#
#
#
#
<0.1
0.1
0.1
#
#
#
#
#
#
#
<0.1
0.1
#
#
#
#
#
#
#
#
<0.1
       #  < 0.1 mile (report distance as 0.1 mile)
April 15, 1999
                                                               10-22

-------
                                      Reference Table 29
                        Dense Gas Distances to Lower Flammability Limit
                 Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second
Release
Rate
(Ibs/min)
<5,000
5,000
7,500
10,000
Lower Flammability Limit (mg/L)
27
30
35
40
>40
Distance (Miles)
#
<0.1
0.1
0.1
#
<0.1
0.1
0.1
#
#
<0.1
0.1
#
#
#
<0.1
#
#
#
#
                      # < 0.1 mile (report distance as 0.1 mile)
April 15, 1999
                                            10-23

-------
                                                      Reference Table 30
    Distance to Radiant Heat Dose at Potential Second Degree Burn Threshold Assuming Exposure for Duration of Fireball from BLEVE
                                             (Dose = [5 kW/rn2]4'3 x Exposure Time)
Quantity in Fireball (pounds)
Duration of Fireball (seconds)
CAS No.
75-07-0
74-86-2
598-73-2
106-99-0
106-97-8
106-98-9
107-01-7
25167-67-3
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
Chemical Name
Acetaldehyde
Acetylene
Bromotrifluoroethylene
1,3-Butadiene
Butane
1-Butene
2-Butene
Butene
2-Butene-cis
2-Butene-trans
Carbon oxysulfide
Chlorine monoxide
2-Chloropropylene
1 -Chloropropylene
Cyanogen
Cyclopropane
Dichlorosilane
Difluoroethane
Dimethylamine
2,2-Dimethylpropane
Ethane
Ethyl acetylene
1,000
3.5
5,000
5.9
10,000
7.5
20,000
9.4
30,000
10.8
50,000
12.7
75,000
14.8
100,000
15.5
200,000
17.4
300,000
18.7
500,000
20.3
Distance (miles) at which Exposure for Duration of Fireball May Cause Second Degree Burns
0.04
0.05
0.01
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.02
0.01
0.03
0.03
0.03
0.05
0.02
0.02
0.04
0.05
0.05
0.05
0.08
0.1
0.02
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.05
0.02
0.07
0.07
0.07
0.1
0.04
0.05
0.09
0.1
0.1
0.1
0.1
0.1
0.03
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.06
0.02
0.1
0.1
0.1
0.1
0.06
0.07
0.1
0.1
0.1
0.1
0.1
0.2
0.04
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.09
0.03
0.1
0.1
0.1
0.2
0.08
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.05
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.1
0.03
0.2
0.2
0.2
0.2
0.1
0.1
0.2
0.2
0.2
0.2
0.2
0.3
0.06
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.1
0.04
0.2
0.2
0.2
0.3
0.1
0.1
0.3
0.3
0.3
0.3
0.3
0.4
0.07
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.2
0.05
0.2
0.2
0.2
0.4
0.2
0.2
0.3
0.4
0.4
0.4
0.3
0.4
0.08
0.4
0.4
0.4
0.4
0.4
0.4
0.4
0.2
0.06
0.3
0.3
0.3
0.4
0.2
0.2
0.4
0.4
0.4
0.4
0.4
0.5
0.1
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.2
0.08
0.4
0.4
0.4
0.5
0.2
0.3
0.5
0.5
0.5
0.5
0.5
0.6
0.1
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.3
0.09
0.4
0.4
0.4
0.6
0.3
0.3
0.5
0.6
0.6
0.6
0.6
0.8
0.2
0.8
0.8
0.8
0.8
0.8
0.8
0.8
0.3
0.1
0.5
0.5
0.5
0.8
0.3
0.4
0.7
0.8
0.8
0.8
April 15, 1999
                                                            10-24

-------
                                                          Reference Table 30 (continued)
Quantity in Fireball (pounds)
Duration of Fireball (seconds)
CAS No.
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
Chemical Name
Ethylamine
Ethyl chloride
Ethylene
Ethyl ether
Ethyl mercaptan
Ethyl nitrite
Hydrogen
Isobutane
Isopentane
Isoprene
Isopropylamine
Isopropyl chloride
Methane
Methylamine
3 -Methyl- 1-butene
2-Methyl-l-butene
Methyl ether
Methyl formate
2-Methylpropene
1,3-Pentadiene
Pentane
1-Pentene
2-Pentene, (EV
1,000
3.5
5,000
5.9
10,000
7.5
20,000
9.4
30,000
10.8
50,000
12.7
75,000
14.8
100,000
15.5
200,000
17.4
300,000
18.7
500,000
20.3
Distance (miles) at which Exposure for Duration of Fireball May Cause Second Degree Burns
0.04
0.03
0.05
0.04
0.04
0.03
0.08
0.05
0.05
0.05
0.04
0.04
0.05
0.04
0.05
0.05
0.04
0.03
0.05
0.05
0.05
0.05
0.05
0.09
0.07
0.1
0.09
0.08
0.06
0.2
0.1
0.1
0.1
0.09
0.07
0.1
0.08
0.1
0.1
0.08
0.06
0.1
0.1
0.1
0.1
0.1
0.1
0.09
0.1
0.1
0.1
0.09
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.08
0.1
0.1
0.1
0.1
0.1
0.2
0.1
0.2
0.2
0.2
0.1
0.3
0.2
0.2
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.1
0.4
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.2
0.3
0.2
0.3
0.2
0.2
0.2
0.5
0.3
0.3
0.3
0.3
0.2
0.3
0.2
0.3
0.3
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.2
0.4
0.3
0.3
0.2
0.6
0.4
0.4
0.4
0.3
0.3
0.4
0.3
0.4
0.4
0.3
0.2
0.4
0.3
0.4
0.4
0.4
0.4
0.3
0.4
0.3
0.3
0.3
0.6
0.4
0.4
0.4
0.4
0.3
0.4
0.3
0.4
0.4
0.3
0.2
0.4
0.4
0.4
0.4
0.4
0.5
0.3
0.5
0.5
0.4
0.3
0.9
0.5
0.5
0.5
0.5
0.4
0.6
0.4
0.5
0.5
0.4
0.3
0.5
0.5
0.5
0.5
0.5
0.5
0.4
0.6
0.5
0.5
0.4
1.0
0.6
0.6
0.6
0.6
0.4
0.6
0.5
0.6
0.6
0.5
0.4
0.6
0.6
0.6
0.6
0.6
0.7
0.5
0.8
0.7
0.6
0.5
1.2
0.8
0.8
0.7
0.7
0.5
0.8
0.6
0.8
0.7
0.6
0.4
0.8
0.7
0.8
0.8
0.8
April 15, 1999
                                                                     10-25

-------
                                                          Reference Table 30 (continued)
Quantity in Fireball (pounds)
Duration of Fireball (seconds)
CAS No.
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
Chemical Name
2-Pentene, (Z)-
Propadiene
Propane
Propylene
Propyne
Silane
Tetrafluoroethylene
Tetramethylsilane
Trichlorosilane
Trifluorochloroethylene
Trimethylamine
Vinyl acetylene
Vinyl chloride
Vinyl ethyl ether
Vinyl fluoride
Vinylidene chloride
Vinylidene fluoride
Vinyl methyl ether
1,000
3.5
5,000
5.9
10,000
7.5
20,000
9.4
30,000
10.8
50,000
12.7
75,000
14.8
100,000
15.5
200,000
17.4
300,000
18.7
500,000
20.3
Distance (miles) at which Exposure for Duration of Fireball May Cause Second Degree Burns
0.05
0.05
0.05
0.05
0.05
0.05
0.01
0.05
0.01
0.01
0.04
0.05
0.03
0.04
0.01
0.02
0.02
0.04
0.1
0.1
0.1
0.1
0.1
0.1
0.02
0.1
0.03
0.02
0.09
0.1
0.07
0.09
0.02
0.05
0.05
0.08
0.1
0.1
0.1
0.1
0.1
0.1
0.02
0.1
0.04
0.03
0.1
0.1
0.09
0.1
0.03
0.07
0.07
0.1
0.2
0.2
0.2
0.2
0.2
0.2
0.03
0.2
0.06
0.04
0.2
0.2
0.1
0.2
0.04
0.09
0.09
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.04
0.2
0.07
0.05
0.2
0.2
0.2
0.2
0.05
0.1
0.1
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.05
0.3
0.08
0.06
0.3
0.3
0.2
0.2
0.06
0.1
0.1
0.2
0.4
0.4
0.4
0.4
0.4
0.4
0.06
0.3
0.1
0.07
0.3
0.4
0.2
0.3
0.08
0.2
0.2
0.3
0.4
0.4
0.4
0.4
0.4
0.4
0.07
0.4
0.1
0.08
0.4
0.4
0.3
0.3
0.09
0.2
0.2
0.3
0.5
0.5
0.5
0.5
0.5
0.5
0.09
0.5
0.2
0.1
0.5
0.5
0.3
0.4
0.1
0.3
0.3
0.4
0.6
0.6
0.6
0.6
0.6
0.6
0.1
0.6
0.2
0.1
0.6
0.6
0.4
0.5
0.1
0.3
0.3
0.5
0.8
0.8
0.8
0.8
0.8
0.7
0.1
0.7
0.2
0.2
0.7
0.8
0.5
0.6
0.2
0.4
0.4
0.6
April 15, 1999
                                                                     10-26

-------
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 recent 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 LandView 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 within 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, provide 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, 1999

-------
Chapter 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 schools, residences, hospitals,
prisons, public recreational areas, or commercial, 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).  Commercial and industrial areas include shopping
malls, strip malls, downtown business areas, industrial parks, etc. See EPA's General Guidance for Risk
Management Programs (40 CFRpart 68) for further information on identifying public receptors.

        Environmental  receptors are defined as national or state parks, forests, 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 receptors 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                                       11-2

-------
                                                                                                Chapter 11
                                                                                Estimating Offsite Receptors
  How to obtain TJSGS 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) products, 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                                        11-3

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Chapter 11
Estimating Offsite Receptors
                               This page intentionally left blank.
April 15, 1999                                    11-4

-------
12     SUBMITTING OFFSITE CONSEQUENCE ANALYSIS
        INFORMATION FOR RISK 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 and alternative release scenario(s) for toxic and flammable regulated chemicals held above
the threshold quantity. The requirements for what information you must submit differ if your source has
Program 1, Program 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 affected
by the initial worst-case scenario(s) for flammable and toxic regulated substances.

        In addition to a worst-case release scenario, sources with Program 2 and Program 3 processes must
also provide information on alternative release scenarios.  Alternative releases are releases that could occur,
other than the worst-case, that may result in concentrations, overpressures, or radiant heat that reach
endpoints offsite.  You must present information on one alternative release scenario for each regulated toxic
substance, including the substance 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.  The
types of documentation to submit are presented below for worst-case scenarios involving toxic substances,
alternative scenarios involving toxic substances, worst-case scenarios involving flammable 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*Submit User Manual for complete instructions.

        •      Chemical name;
        •      Percentage weight of the regulated liquid toxic substance (if present in a mixture);
April 12, 1999

-------
Chapter 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, commercial, office 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); 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 substances held above the threshold quantity in a Program 2
or Program 3 process, you will have to submit the following information. See the Risk Management Plan
Data Elements Guide for complete instructions.

        •       Chemical name;
        •       Percentage weight of the regulated liquid toxic substance (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                                      12-2

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                                                                                          Chapter 12
	Submitting Offsite Consequence Analysis Information for Risk Management Plan

        •      Public receptors within the distance to endpoint (schools, residences, hospitals, prisons,
               recreation areas, commercial, office, 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 (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 substances, you will have to submit the following
information.  See the Risk Management Plan Data Elements Guide 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, commercial, office, 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);  and
        •      Passive mitigation measures considered (blast walls, other).

        12.4   RMP Data Required for Alternative  Scenarios for Flammable Substances

        For alternative scenarios involving flammable substances held above the threshold quantity in a
Program 2 or Program 3 process, you will have to submit the following information. See the Risk
Management Plan Data Elements Guide 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/m2 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                                      12-3

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Chapter 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, office, 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's automated tool for submitting RMPs, RMP*Submit is available free from the EPCRA hotline
(on disk) or can be downloaded from www.epa.gov/ceppo/. The RMP*Submit  User's Manual provides
detailed instructions for each data element.  RMP*Submit does the following:

        •      Provides a user-friendly, PC-based RMP Submission System available on diskettes and via
               the Internet;
        •      Uses a standards-based, open systems architecture so private companies can create
               compatible  software; and
        •      Performs data quality checks, accept limited graphics, and provide on-line help including
               defining data elements and providing instructions.

The software runs on Windows 3.1 and above.  There will not be a DOS or MAC version.

        If you are unable to submit electronically for any reason, just fill out the Electronic Waiver form
available in the RMP*Submit User's Manual and send it in with your RMP.  See the RMP*Submit User's
Manual for more information on the Electronic Waiver.

        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 vessel 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.
        •      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
April 12, 1999                                      12-4

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                                                                                             Chapter 12
	Submitting Offsite Consequence Analysis Information for Risk Management Plan

                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.
April 12, 1999                                       12-5

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                       APPENDIX A




     REFERENCES FOR CONSEQUENCE ANALYSIS METHODS
April 15, 1999

-------
APPENDIX A    REFERENCES FOR CONSEQUENCE ANALYSIS
                   METHODS

      Exhibit A-1 lists references that may provide useful information for modeling or calculation methods
that could be used in the offsite consequence analyses. This exhibit is not intended to be a complete listing of
references that may be used in the consequence analysis; any appropriate model or method may be used.
April 15, 1999

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Appendix A
References for Consequence Analysis Methods
                                          Exhibit A-l
           Selected References for Information on Consequence Analysis Methods

Center for Process Safety of the American Institute of Chemical Engineers (AIChE).  Guidelines for
       Evaluating the Characteristics of Vapor Cloud Explosions, Flash Fires, andBLEVEs. New York:
       AIChE, 1994.

Center for Process Safety of the American Institute of Chemical Engineers (AIChE).  Guidelines for Use of
       Vapor Cloud Dispersion Models, Second Ed. New York: AIChE, 1996.

Center for Process Safety of the American Institute of Chemical Engineers (AIChE).  International
       Conference and Workshop on Modeling and Mitigating the Consequences of Accidental Releases
       of Hazardous Materials, September 26-29, 1995. New York: AIChE, 1995.

Federal Emergency Management Agency, U.S. Department of Transportation, U.S. Environmental Protection
       Agency.  Handbook oj'Chemical Hazard Analysis Procedures.  1989.

Madsen, Warren W. and Robert C. Wagner.  "An Accurate Methodology for Modeling the Characteristics of
       Explosion Effects."  Process Safety Progress, 13 (July 1994), 171-175.

Mercx, W.P.M., D.M. Johnson, and J. Puttock. "Validation of Scaling Techniques for Experimental Vapor
       Cloud Explosion Investigations."  Process Safety Progress, 14 (April 1995), 120.

Mercx, W.P.M., R.M.M. van Wees, and G. Opschoor. "Current Research at TNO on Vapor Cloud Explosion
       Modelling." Process Safety Progress, 12 (October 1993), 222.

Prugh, Richard W.  "Quantitative Evaluation of Fireball Hazards." Process Safety Progress, 13 (April
       1994), 83-91.

Scheuermann, Klaus P. "Studies About the Influence of Turbulence on the Course of Explosions." Process
       Safety Progress, 13 (October 1994), 219.

TNO Bureau for Industrial Safety, Netherlands Organization for Applied Scientific Research. Methods for
       the Calculation of the Physical Effects.  The Hague, the Netherlands: Committee for the Prevention
       of Disasters, 1997.

TNO Bureau for Industrial Safety, Netherlands Organization for Applied Scientific Research. Methods for
       the Calculation of the Physical Effects of the Escape of Dangerous Material (Liquids and Gases).
       Voorburg, the Netherlands:  TNO (Commissioned by Directorate-General of Labour), 1980.

TNO Bureau for Industrial Safety, Netherlands Organization for Applied Scientific Research. Methods for
       the Calculation of the Physical Effects Resulting from Releases of Hazardous Materials. Rijswijk,
       the Netherlands:  TNO (Commissioned by Directorate-General of Labour), 1992.

TNO Bureau for Industrial Safety, Netherlands Organization for Applied Scientific Research. Methods for
       the Determination of Possible Damage to People and Objects Resulting from Releases of

April 15, 1999                                    A - 2

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                                                                                     Appendix A
                                                          References for Consequence Analysis Methods
       Hazardous Materials. Rijswijk, the Netherlands:  TNO (Commissioned by Directorate-General of
       Labour), 1992.

Touma, Jawad S., et al.  "Performance Evaluation of Dense Gas Dispersion Models." Journal of Applied
       Meteorology, 34 (March 1995), 603-615.

U.S. Environmental Protection Agency, Federal Emergency Management Agency, U.S. Department of
       Transportation. Technical Guidance for Hazards Analysis, Emergency Planning for Extremely
       Hazardous Substances. December 1987.

U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards. Workbook of
       Screening Techniques for Assessing Impacts of Toxic Air Pollutants. EPA-450/4-88-009.
       September 1988.

U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards. Guidance on the
       Application of Refined Dispersion Models for Hazardous/Toxic Air Release. EPA-454/R-93-002.
       May 1993.

U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxic Substances. Flammable
       Gases and Liquids and Their Hazards. EPA 744-R-94-002.  February 1994.
April 15, 1999                                    A - 3

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                        APPENDIX B




                     TOXIC SUBSTANCES
April 15, 1999

-------
APPENDIX B    TOXIC SUBSTANCES

        B.I    Data for Toxic Substances

        The exhibits in this section of Appendix B provide the data needed to carry out the calculations for
regulated toxic substances using the methods presented in the text of this guidance. Exhibit B-l presents
data for toxic gases, Exhibit B-2 presents data for toxic liquids, and Exhibit B-3 presents data for several
toxic substances commonly found in water solution and for oleum. Exhibit B-4 provides temperature
correction factors that can be used to correct the release rates estimated for pool evaporation of toxic liquids
that are released at temperatures between 25 °C to 50 °C.

        The derivation of the factors presented in Exhibits B-l - B-4 is discussed in Appendix D. The data
used to develop the factors in Exhibits B-l and B-2 are primarily from Design Institute for Physical Property
Data (DIPPR), American Institute of Chemical Engineers, Physical and Thermodynamic Properties of Pure
Chemicals, Data Compilation.  Other sources, including the National Library of Medicine's Hazardous
Substances Databank (HSDB) and the Kirk-Othmer Encyclopedia of Chemical Technology,  were used for
Exhibits B-1 and B-2 if data were not available from the DIPPR compilation. The factors in Exhibit B-3
were developed using data primarily from Perry's Chemical Engineers' Handbook and the Kirk-Othmer
Encyclopedia of Chemical Technology.  The temperature correction factors in Exhibit B-4 were developed
using vapor pressure data derived from the vapor pressure coefficients  in the DIPPR compilation.
April 15, 1999

-------
                                                       Exhibit B-l
                                                   Data for Toxic Gases
CAS
Number
7664-41-7
7784-42-1
10294-34-5
7637-07-2
7782-50-5
10049-04-4
506-77-4
19287-45-7
75-21-8
7782-41-4
50-00-0
74-90-8
7647-01-0
7664-39-3
7783-07-5
7783-06-4
74-87-3
74-93-1
10102-43-9
75-44-5
Chemical Name
Ammonia (anhydrous)0
Arsine
Boron trichloride
Boron trifluoride
Chlorine
Chlorine dioxide
Cyanogen chloride
Diborane
Ethylene oxide
Fluorine
Formaldehyde (anhydrous)0
Hydrocyanic acid
Hydrogen chloride
(anhydrous)0
Hydrogen fluoride
(anhydrous)0
Hydrogen selenide
Hydrogen sulfide
Methyl chloride
Methyl mercaptan
Nitric oxide
Phosgene
Molecular
Weight
17.03
77.95
117.17
67.81
70.91
67.45
61.47
27.67
44.05
38.00
30.03
27.03
36.46
20.01
80.98
34.08
50.49
48.11
30.01
98.92
Ratio of
Specific
Heats
1.31
1.28
1.15
1.20
1.32
1.25
1.22
1.17
1.21
1.36
1.31
1.30
1.40
1.40
1.32
1.32
1.26
1.20
1.38
1.17
Toxic Endpoint3
mg/L
0.14
0.0019
0.010
0.028
0.0087
0.0028
0.030
0.0011
0.090
0.0039
0.012
0.011
0.030
0.016
0.00066
0.042
0.82
0.049
0.031
0.00081
ppm
200
0.6
2
10
3
1
12
1
50
2.5
10
10
20
20
0.2
30
400
25
25
0.2
Basis
ERPG-2
EHS-LOC (IDLH)
EHS-LOC (Toxe)
EHS-LOC (IDLH)
ERPG-2
EHS-LOC
equivalent (IDLH)8
EHS-LOC
equivalent (Tox)
ERPG-2
ERPG-2
EHS-LOC (IDLH)
ERPG-2
ERPG-2
ERPG-2
ERPG-2
EHS-LOC (IDLH)
ERPG-2
ERPG-2
ERPG-2
EHS-LOC (TLVj)
ERPG-2
Liquid Factor
Boiling
(LFB)
0.073
0.23
0.22
0.25
0.19
0.15
0.14
0.13
0.12
0.35
0.10
0.079
0.15
0.066
0.21
0.13
0.14
0.12
0.21
0.20
Density
Factor (DF)
(Boiling)
0.71
0.30
0.36
0.31
0.31
0.30
0.41
1.13
0.55
0.32
0.59
0.72
0.41
0.51
0.25
0.51
0.48
0.55
0.38
0.35
Gas
Factor
(GF)k
14
30
36
28
29
28
26
17
22
22
19
18
21
16
31
20
24
23
19
33
Vapor
Pressure
@25 °C (psia)
145
239
22.7
f
113
24.3
23.7
f
25.4
f
75.2
14.8
684
17.7
151
302
83.2
29.2
f
27.4
Reference
Table"
Buoyant4
Dense
Dense
Dense
Dense
Dense
Dense
Buoyant4
Dense
Dense
Dense
Buoyant4
Dense
Buoyant1
Dense
Dense
Dense
Dense
Dense
Dense
April 15, 1999
                                                           B-2

-------
                                                            Exhibit B-l (continued)
CAS
Number
7803-51-2
7446-09-5
7783-60-0
Chemical Name
Phosphine
Sulfur dioxide (anhydrous)
Sulfur tetrafluoride
Molecular
Weight
34.00
64.07
108.06
Ratio of
Specific
Heats
1.29
1.26
1.30
Toxic Endpoint3
mg/L
0.0035
0.0078
0.0092
ppm
2.5
3
2
Basis
ERPG-2
ERPG-2
EHS-LOC (Toxe)
Liquid Factor
Boiling
(LFB)
0.15
0.16
0.25
Density
Factor (DF)
(Boiling)
0.66
0.33
0.25
(at -73 °C)
Gas
Factor
(GF)k
20
27
36
Vapor
Pressure
@25 °C (psia)
567
58.0
293
Reference
Table"
Dense
Dense
Dense
Notes:

a Toxic endpoints are specified in Appendix A to 40 CFR part 68 in units of mg/L.  To convert from units of mg/L to mg/m3, multiply by 1,000.  To convert mg/L to
ppm, use the following equation:
                                                     Endpoint
                                                             ppm
EndpointmgjL  x  1,000 x 24.5
     Molecular Weight
b "Buoyant" in the Reference Table column refers to the tables for neutrally buoyant gases and vapors; "Dense" refers to the tables for dense gases and vapors.  See
Appendix D, Section D.4.4, for more information on the choice of reference tables.
0 See Exhibit B-3 of this appendix for data on water solutions.
  Gases that are lighter than air may behave as dense gases upon release if liquefied under pressure or cold; consider the conditions of release when choosing the
appropriate table.
e LOG is based on the IDLH-equivalent level estimated from toxicity data.
f Cannot be liquefied at 25 °C.
8 Not  an EHS; LOC-equivalent value was estimated from one-tenth of the IDLH.
h Not  an EHS; LOC-equivalent value was estimated from one-tenth of the IDLH-equivalent level estimated from toxicity data.
1 Hydrogen fluoride is lighter than air, but may behave as a dense gas upon release under some circumstances (e.g., release under pressure, high concentration in the
released cloud) because of hydrogen bonding; consider the conditions of release when choosing the appropriate table.
J LOG based on Threshold Limit Value (TLV) - Time-weighted average (TWA) developed by the American Conference of Governmental Industrial Hygienists
(ACGIH).
  Use  GF for gas leaks under choked (maximum) flow conditions.
April 15, 1999
                                                                       B-3

-------
                                                        Exhibit B-2
                                                  Data for Toxic Liquids
CAS
Number
107-02-8
107-13-1
814-68-6
107-18-6
107-11-9
7784-34-1
353-42-4
7726-95-6
75-15-0
67-66-3
542-88-1
107-30-2
4170-30-3
123-73-9
108-91-8
75-78-5
57-14-7
106-89-8
107-15-3
151-56-4
110-00-9
302-01-2
Chemical Name
Acrolein
Acrylonitrile
Acrylyl chloride
Allyl alcohol
Allylamine
Arsenous trichloride
Boron trifluoride compound
with methyl ether (1:1)
Bromine
Carbon disulfide
Chloroform
Chloromethyl ether
Chloromethyl methyl ether
Crotonaldehyde
Crotonaldehyde, (E)-
Cyclohexylamine
Dimethyldichlorosilane
1 , 1 -Dimethylhydrazine
Epichlorohydrin
Ethylenediamine
Ethyleneimine
Furan
Hvdrazine
Molecular
Weight
56.06
53.06
90.51
58.08
57.10
181.28
113.89
159.81
76.14
119.38
114.96
80.51
70.09
70.09
99.18
129.06
60.10
92.53
60.10
43.07
68.08
32.05
Vapor
Pressure
at 25 °C
(mmHg)
274
108
110
26.1
242
10
11
212
359
196
29.4
199
33.1
33.1
10.1
141
157
17.0
12.2
211
600
14.4
Toxic Endpoint3
mg/L
0.0011
0.076
0.00090
0.036
0.0032
0.01
0.023
0.0065
0.16
0.49
0.00025
0.0018
0.029
0.029
0.16
0.026
0.012
0.076
0.49
0.018
0.0012
0.011
ppm
0.5
35
0.2
15
1
1
5
1
50
100
0.05
0.6
10
10
39
5
5
20
200
10
0.4
8
Basis
ERPG-2
ERPG-2
EHS-LOC (Toxc)
EHS-LOC (IDLH)
EHS-LOC (Toxc)
EHS-LOC (Toxc)
EHS-LOC (Toxc)
ERPG-2
ERPG-2
EHS-LOC (IDLH)
EHS-LOC (Toxc)
EHS-LOC (Toxc)
ERPG-2
ERPG-2
EHS-LOC (Toxc)
ERPG-2
EHS-LOC (IDLH)
ERPG-2
EHS-LOC (IDLH)
EHS-LOC (IDLH)
EHS-LOC (Toxc)
EHS-LOC (IDLH)
Liquid Factors
Ambient
(LFA)
0.047
0.018
0.026
0.0046
0.042
0.0037
0.0030
0.073
0.075
0.055
0.0080
0.043
0.0066
0.0066
0.0025
0.042
0.028
0.0040
0.0022
0.030
0.12
0.0017
Boiling
(LFB)
0.12
0.11
0.15
0.11
0.12
0.21
0.16
0.23
0.15
0.19
0.17
0.15
0.12
0.12
0.14
0.20
0.12
0.14
0.13
0.10
0.14
0.069
Density
Factor
(DF)
0.58
0.61
0.44
0.58
0.64
0.23
0.49
0.16
0.39
0.33
0.37
0.46
0.58
0.58
0.56
0.46
0.62
0.42
0.54
0.58
0.52
0.48
Liquid
Leak
Factor
(LLF)1
40
39
54
41
36
100
48
150
60
71
63
51
41
41
41
51
38
57
43
40
45
48
Reference Tableb
Worst
Case
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Buoyant
Alternative
Case
Dense
Dense
Dense
Buoyant
Dense
Buoyant
Buoyant
Dense
Dense
Dense
Dense
Dense
Buoyant
Buoyant
Buoyant
Dense
Dense
Buoyant
Buoyant
Dense
Dense
Buoyant
April 15, 1999
                                                           B-4

-------
                                                  Exhibit B-2 (continued)
CAS
Number
13463-40-6
78-82-0
108-23-6
126-98-7
79-22-1
60-34-4
624-83-9
556-64-9
75-79-6
13463-39-3
7697-37-2
79-21-0
594-42-3
10025-87-3
7719-12-2
110-89-4
107-12-0
109-61-5
75-55-8
75-56-9
7446-11-9
75-74-1
509-14-8
Chemical Name
Iron, pentacarbonyl-
Isobutyronitrile
Isopropyl chloroformate
Methacrylonitrile
Methyl chloroformate
Methyl hydrazine
Methyl isocyanate
Methyl thiocyanate
Methyltrichlorosilane
Nickel carbonyl
Nitric acid (100%)f
Peracetic acid
Perchloromethylmercaptan
Phosphorus oxychloride
Phosphorus trichloride
Piperidine
Propionitrile
Propyl chloroformate
Propyleneimine
Propylene oxide
Sulfur trioxide
Tetramethyllead
Tetranitromethane
Molecular
Weight
195.90
69.11
122.55
67.09
94.50
46.07
57.05
73.12
149.48
170.73
63.01
76.05
185.87
153.33
137.33
85.15
55.08
122.56
57.10
58.08
80.06
267.33
196.04
Vapor
Pressure
at 25 °C
(mmHg)
40
32.7
28
71.2
108
49.6
457
10
173
400
63.0
13.9
6
35.8
120
32.1
47.3
20.0
187
533
263
22.5
11.4
Toxic Endpoint3
mg/L
0.00044
0.14
0.10
0.0027
0.0019
0.0094
0.0012
0.085
0.018
0.00067
0.026
0.0045
0.0076
0.0030
0.028
0.022
0.0037
0.010
0.12
0.59
0.010
0.0040
0.0040
ppm
0.05
50
20
1
0.5
5
0.5
29
3
0.1
10
1.5
1
0.5
5
6
1.6
2
50
250
3
0.4
0.5
Basis
EHS-LOC (Toxc)
ERPG-2
EHS-LOC (Toxc)
EHS-LOC (TLVe)
EHS-LOC (Toxc)
EHS-LOC (IDLH)
ERPG-2
EHS-LOC (Toxc)
ERPG-2
EHS-LOC (Toxc)
EHS-LOC (Toxc)
EHS-LOC (Toxc)
EHS-LOC (IDLH)
EHS-LOC (Toxc)
EHS-LOC (IDLH)
EHS-LOC (Toxc)
EHS-LOC (Toxc)
EHS-LOC (Toxc)
EHS-LOC (IDLH)
ERPG-2
ERPG-2
EHS-LOC (IDLH)
EHS-LOC (IDLH)
Liquid Factors
Ambient
(LFA)
0.016
0.0064
0.0080
0.014
0.026
0.0074
0.079
0.0020
0.057
0.14
0.012
0.0029
0.0023
0.012
0.037
0.0072
0.0080
0.0058
0.032
0.093
0.057
0.011
0.0045
Boiling
(LFB)
0.24
0.12
0.17
0.12
0.16
0.094
0.13
0.11
0.22
0.26
0.12
0.12
0.20
0.20
0.20
0.13
0.10
0.17
0.12
0.13
0.15
0.29
0.22
Density
Factor
(DF)
0.33
0.63
0.45
0.61
0.40
0.56
0.52
0.45
0.38
0.37
0.32
0.40
0.29
0.29
0.31
0.57
0.63
0.45
0.61
0.59
0.26
0.24
0.30
Liquid
Leak
Factor
(LLF)1
70
37
52
38
58
42
45
51
61
63
73
58
81
80
75
41
37
52
39
40
91
96
78
Reference Tableb
Worst
Case
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Alternative
Case
Dense
Buoyant
Dense
Dense
Dense
Buoyant
Dense
Buoyant
Dense
Dense
Dense
Buoyant
Buoyant
Dense
Dense
Buoyant
Buoyant
Buoyant
Dense
Dense
Dense
Dense
Buoyant
April 15, 1999
                                                            B-5

-------
                                                           Exhibit B-2 (continued)
CAS
Number
7550-45-0
584-84-9
91-08-7
26471-62-5
75-77-4
108-05-4
Chemical Name
Titanium tetrachloride
Toluene 2,4-diisocyanate
Toluene 2,6-diisocyanate
Toluene diisocyanate
(unspecified isomer)
Trimethylchlorosilane
Vinyl acetate monomer
Molecular
Weight
189.69
174.16
174.16
174.16
108.64
86.09
Vapor
Pressure
at 25 °C
(mmHg)
12.4
0.017
0.05
0.017
231
113
Toxic Endpoint3
mg/L
0.020
0.0070
0.0070
0.0070
0.050
0.26
ppm
2.6
1
1
1
11
75
Basis
ERPG-2
EHS-LOC (IDLH)
EHS-LOC (IDLH8)
EHS-LOC equivalent
(IDLH11)
EHS-LOC (Toxc)
ERPG-2
Liquid Factors
Ambient
(LFA)
0.0048
0.000006
0.000018
0.000006
0.061
0.026
Boiling
(LFB)
0.21
0.16
0.16
0.16
0.18
0.15
Density
Factor
(DF)
0.28
0.40
0.40
0.40
0.57
0.53
Liquid
Leak
Factor
(LLF)1
82
59
59
59
41
45
Reference Tableb
Worst
Case
Dense
Buoyant
Buoyant
Buoyant
Dense
Dense
Alternative
Case
Buoyant
Buoyant
Buoyant
Buoyant
Dense
Dense
Notes:
a Toxic endpoints are specified in the Appendix A to 40 CFR part 68 in units of mg/L. To convert from units of mg/L to mg/m3, multiply by 1,000. To convert mg/L
to ppm, use the following equation:
                                                     Endpoint
                                                                   Endpoint
                                                                           'mg/L
1,000 x 24.5
                                                             ppm
                                                                        Molecular Weight
b "Buoyant" in the Reference Table column refers to the tables for neutrally buoyant gases and vapors; "Dense" refers to the tables for dense gases and vapors.  See
Appendix D, Section D.4.4, for more information on the choice of reference tables.
0 LOG is based on IDLH-equivalent level estimated from toxicity data.
  Use dense gas table if substance is at an elevated temperature.
e LOG based on Threshold Limit  Value (TLV) - Time-weighted average (TWA) developed by the American Conference of Governmental Industrial Hygienists
(ACGIH).
f See Exhibit B-3 of this appendix for data on water solutions.
8 LOG for this isomer is based on IDLH for toluene 2,4-diisocyanate.
h Not an EHS; LOC-equivalent value is based on IDLH for toluene 2,4-diisocyanate.
1 Use the LLF only for leaks from tanks at atmospheric pressure.
April 15, 1999
                                                                       B-6

-------
                                                                Exhibit B-3
                                     Data for Water Solutions of Toxic Substances and for Oleum
                                       For Wind Speeds of 1.5 and 3.0 Meters per Second (m/s)
CAS
Number
7664-41-7
50-00-0
7647-01-0
7664-39-3
7697-37-2
8014-95-7
Regulated
Substance
in Solution
Ammonia
Formaldehyde
Hydrochloric
acid
Hydrofluoric
acid
Nitric acid
Oleum - based
onSO3
Molecular
Weight
17.03
30.027
36.46
20.01
63.01
80.06
(S03)
Toxic Endpoint3
mg/L
0.14
0.012
0.030
0.016
0.026
0.010
ppm
200
10
20
20
10
3
Basis
ERPG-2
ERPG-2
ERPG-2
ERPG-2
EHS-
LOC
(IDLH)
ERPG-2
Initial
Concen-
tration
(Wt %)
30
24
20
37
38
37
36C
34C
30C
70
50
90
85
80
30 (SO3)
10-min. Average Vapor
Pressure (nun Hg)
1.5 m/s
332
241
190
1.5
78
67
56
38
13
124
16
25
17
10.2
3.5 (S03)
3.0 m/s
248
184
148
1.4
55
48
42
29
12
107
15
22
16
10
3.4 (S03)
Liquid Factor at 25° C
(LFA)
1.5 m/s
0.026
0.019
0.015
0.0002
0.010
0.0085
0.0072
0.0048
0.0016
0.011
0.0014
0.0046
0.0032
0.0019
0.0008
3.0 m/s
0.019
0.014
0.011
0.0002
0.0070
0.0062
0.0053
0.0037
0.0015
0.010
0.0013
0.0040
0.0029
0.0018
0.0007
Density
Factor
(DF)
0.55
0.54
0.53
0.44
0.41
0.42
0.42
0.42
0.42
0.39
0.41
0.33
0.33
0.33
0.25
Liquid
Leak
Factor
(LLF)
43
44
44
53
57
57
57
56
55
61
58
71
70
70
93
Reference Tableb
Worst
Buoyant
Buoyant
Buoyant
Buoyant
Dense
Dense
Dense
Dense
Buoyant
Buoyant
Buoyant
Dense
Dense
Dense
Buoyant
Alternative
Buoyant
Buoyant
Buoyant
Buoyant
Buoyant d
Buoyant d
Buoyant d
Buoyant d
Buoyant d
Buoyant
Buoyant
Buoyant d
Buoyant d
Buoyant d
Buoyant d
Notes:

a Toxic endpoints are specified in the Appendix A to 40 CFR part 68 in units of mg/L. See Notes to Exhibit B-l or B-2 for converting to other units.
b "Buoyant" in the Reference Table column refers to the tables for neutrally buoyant gases and vapors; "Dense" refers to the tables for dense gases and vapors. See
Appendix D, Section D.4.4, for more information on the choice of reference tables.
0 Hydrochloric acid in concentrations below 37 percent is not regulated.
d Use dense gas table if substance is at an elevated temperature.
April 15, 1999
                                                                    B-7

-------
                                    Exhibit B-4
  Temperature Correction Factors for Liquids Evaporating from Pools at Temperatures
                      Between 25 °C and 50 °C (77 °F and 122 °F)
CAS
Number
107-02-8
107-13-1
814-68-6
107-18-6
107-11-9
7784-34-1
353-42-4
7726-95-6
75-15-0
67-66-3
542-88-1
107-30-2
4170-30-3
123-73-9
108-91-8
75-78-5
57-14-7
106-89-8
107-15-3
151-56-4
110-00-9
302-01-2
13463-40-6
78-82-0
108-23-6
126-98-7
79-22-1
60-34-4
624-83-9
556-64-9
75-79-6
Chemical Name
Acrolein
Acrylonitrile
Acrylyl chloride
Allyl alcohol
Allylamine
Arsenous trichloride
Boron trifluoride compound with
methyl ether (1:1)
Bromine
Carbon disulfide
Chloroform
Chloromethyl ether
Chloromethyl methyl ether
Crotonaldehyde
Crotonaldehyde, (E)-
Cyclohexylamine
Dimethyldichlorosilane
1 , 1 -Dimethylhydrazine
Epichlorohydrin
Ethylenediamine
Ethyleneimine
Fur an
Hydrazine
Iron, pentacarbonyl-
Isobutyronitrile
Isopropyl chloroformate
Methacrylonitrile
Methyl chloroformate
Methyl hydrazine
Methyl isocyanate
Methyl thiocyanate
Methyltrichlorosilane
Boiling
Point
(°C)
52.69
77.35
75.00
97.08
53.30
130.06
126.85
58.75
46.22
61.18
104.85
59.50
104.10
102.22
134.50
70.20
63.90
118.50
36.26
55.85
31.35
113.50
102.65
103.61
104.60
90.30
70.85
87.50
38.85
130.00
66.40
Temperature Correction Factor (TCP)
30 °C
(86 °F)
1.2
1.2
ND
1.3
1.2
ND
ND
1.2
1.2
1.2
1.3
1.2
1.3
1.3
1.3
1.2
ND
1.3
1.3
1.2
1.2
1.3
ND
1.3
ND
1.2
1.3
ND
1.2
ND
1.2
35 °C
(95 °F)
1.4
1.5
ND
1.7
1.5
ND
ND
1.5
1.4
1.5
1.6
1.5
1.6
1.6
1.7
1.5
ND
1.7
1.8
1.5
LFB
1.7
ND
1.6
ND
1.5
1.6
ND
1.4
ND
1.4
40 °C
(104 °F)
1.7
1.8
ND
2.2
1.8
ND
ND
1.7
1.6
1.8
2.0
1.8
2.0
2.0
2.1
1.8
ND
2.1
LFB
1.8
LFB
2.2
ND
2.0
ND
1.8
1.9
ND
LFB
ND
1.7
45 °C
(113°F)
2.0
2.1
ND
2.9
2.1
ND
ND
2.1
1.9
2.1
2.5
2.1
2.5
2.5
2.7
2.1
ND
2.7
LFB
2.2
LFB
2.9
ND
2.5
ND
2.2
2.4
ND
LFB
ND
2.0
50 °C
(122 °F)
2.3
2.5
ND
3.6
2.5
ND
ND
2.5
LFB
2.5
3.1
2.5
3.1
3.1
3.4
2.5
ND
3.4
LFB
2.7
LFB
3.6
ND
3.1
ND
2.6
2.9
ND
LFB
ND
2.4
April 15, 1999
                                        B-8

-------
                                            Exhibit B-4 (continued)
CAS
Number
13463-39-3
7697-37-2
79-21-0
594-42-3
10025-87-3
7719-12-2
110-89-4
107-12-0
109-61-5
75-55-8
75-56-9
7446-11-9
75-74-1
509-14-8
7550-45-0
584-84-9
91-08-7
26471-62-5
75-77-4
108-05-4
Chemical Name
Nickel carbonyl
Nitric acid
Peracetic acid
Perchloromethylmercaptan
Phosphorus oxychloride
Phosphorus trichloride
Piperidine
Propionitrile
Propyl chloroformate
Propyleneimine
Propylene oxide
Sulfur trioxide
Tetramethyllead
Tetranitromethane
Titanium tetrachloride
Toluene 2,4-diisocyanate
Toluene 2,6-diisocyanate
Toluene diisocyanate (unspecified
isomer)
Trimethylchlorosilane
Vinyl acetate monomer
Boiling
Point
(°C)
42.85
83.00
109.85
147.00
105.50
76.10
106.40
97.35
112.40
60.85
33.90
44.75
110.00
125.70
135.85
251.00
244.85
250.00
57.60
72.50
Temperature Correction Factor (TCP)
30 °C
(86 °F)
ND
1.3
1.3
ND
1.3
1.2
1.3
1.3
ND
1.2
1.2
1.3
ND
1.3
1.3
1.6
ND
1.6
1.2
1.2
35 °C
(95 °F)
ND
1.6
1.8
ND
1.6
1.5
1.6
1.6
ND
1.5
LFB
1.7
ND
1.7
1.6
2.4
ND
2.4
1.4
1.5
40 °C
(104 °F)
ND
2.0
2.3
ND
1.9
1.8
2.0
1.9
ND
1.8
LFB
LFB
ND
2.2
2.0
3.6
ND
3.6
1.7
1.9
45 °C
(113°F)
ND
2.5
3.0
ND
2.4
2.1
2.4
2.3
ND
2.1
LFB
LFB
ND
2.8
2.6
5.3
ND
5.3
2.0
2.3
50 °C
(122 °F)
ND
3.1
3.8
ND
2.9
2.5
3.0
2.8
ND
2.5
LFB
LFB
ND
3.5
3.2
7.7
ND
7.7
2.3
2.7
Notes:

ND:
LFB:
No data available.
Chemical above boiling point at this temperature; use LFB for analysis.
      April 15, 1999
                                                      B-9

-------
Appendix B
Toxic Substances _

        B.2     Mixtures Containing Toxic Liquids

        In case of a spill of a liquid mixture containing a regulated toxic substance (with the exception of
common water solutions, discussed in Section 3.3 in the text), the area of the pool formed by the entire liquid
spill is determined as described in Section 3.2.2 or 3.2.3. For the area determination, if the density of the
mixture is unknown, the density of the regulated substance in the mixture may be assumed as the density of
the entire mixture.

        If the partial vapor pressure of the regulated substance in the mixture is known, that vapor pressure
may be used to derive a release rate using the equations in Section 3.2.  If the partial vapor pressure of the
regulated toxic substance in the mixture is unknown, it may be estimated from the vapor pressure of the pure
substance (listed in Exhibit B-2, Appendix B) and the concentration in the mixture, if you assume the mixture
is an ideal solution, where an ideal solution is one in which there is complete uniformity of cohesive forces.
This method may overestimate or underestimate the partial pressure for a regulated substance that interacts
with the other components of a mixture or solution. For example, water solutions are generally not ideal.
This method is likely to overestimate the partial pressure of regulated substances in water solution  if there is
hydrogen bonding in the solution (e.g., solutions of acids or alcohols in water).

        To estimate partial pressure for a regulated substance in a mixture or solution, use the following
steps, based on Raoult's Law for ideal solutions:

        •        Determine the mole fraction of the regulated substance in the mixture.

                       The mole fraction of the regulated substance in the mixture is the number of moles
                       of the regulated substance in the mixture divided by the total number of moles of all
                       substances in the mixture.

                       If the molar concentration (moles per liter) of each component of the mixture is
                       known, the mole fraction may be determined as follows:
                                               Mr x  v
                                      xr =  — : -
                                                                                              (B-l)
                or (canceling out Vt):

                                                  Mr

                                                                                              (B-2)
April 15, 1999                                      B - 10

-------
                                                                                        Appendix B
                                                                                   Toxic Substances
        where:  X,.      =      Mole fraction of regulated substance in mixture (unitless)
               Mr      =      Molar concentration of regulated substance in mixture (moles per liter)
               Vt      =      Total volume of mixture (liters)
               n       =      Number of components of mixture
               M;      =      Molar concentration of each component of mixture (moles per liter)
        For a mixture with three components, this would correspond to:
                                                M
                                                  r
                                                M2
                                                                                           (B-3)
        where:  X,.      =      Mole fraction of regulated substance in mixture (unitless)
               Mr      =      Molar concentration of regulated substance (first component) in mixture
                              (moles per liter)
               M2      =      Molar concentration of second component of mixture (moles per liter)
               M3      =      Molar concentration of any other components of mixture (moles per liter)

                       If the weight of each of the components of the mixture is known, the mole fraction
                       of the regulated substance in the mixture may be calculated as follows:
                                                   wr
                                        X.  =
                                                  MW
                                                      r i
                                          r
                                               T
                                               7~t(MWi


        where:  X,.      =      Mole fraction of the regulated substance
               Wr     =      Weight of the regulated substance
               MWr   =      Molecular weight of the regulated substance
               n       =      Number of components of the mixture
               W;     =      Weight of each component of the mixture
               MWj   =      Molecular weight of each component of the mixture

               (Note: Weights can be in any consistent units.)

For a mixture with three components, this corresponds to:
                                                      (B-4)
                                                 MW
                                                      r
_»?,
MW

                                                                                           (B-5)
                                                 MW
                                                      2
April 15, 1999                                    B - 11

-------
Appendix B
Toxic Substances

        where:
       Xr
        Wr
       MWr
        W2
       MW2
       W3
       MW
                              Mole fraction of the regulated substance
                              Weight of the regulated substance (first component of the mixture)
                              Molecular weight of the regulated substance
                              Weight of the second component of the mixture
                              Molecular weight of the second component of the mixture
                              Weight of the third component of the mixture
                              Molecular weight of the third component of the mixture
               (Note: Weights can be in any consistent units.)

               Estimate the partial vapor pressure of the regulated substance in the mixture as follows:
                                                       VP
                                                                                            (B-6)
where:  VP
        VP
                              Partial vapor pressure of the regulated substance in the mixture (millimeters
                              of mercury (mm Hg))
                              Mole fraction of the regulated substance (unitless)
                              Vapor pressure of the regulated substance in pure form at the same
                              temperature as the mixture (mm Hg) (vapor pressure at 25 °C is given in
                              Exhibit B-l, Appendix B)
        The evaporation rate for the regulated substance in the mixture is determined as for pure substances,
with VPm as the vapor pressure.  If the mixture contains more than one regulated toxic substance, carry out
the analysis individually for each of the regulated components. The release rate equation is:

                          0.0035
                                                                A  x VP


where:  QR
        U
        MW
        A

        VP
        T
                              Evaporation rate (pounds per minute)
                              Wind speed (meters per second)
                              Molecular weight (given in Exhibit B-2, Appendix B)
                              Surface area of pool formed by the entire quantity of the mixture (square
                              feet) (determined as described in 3.2.2)
                              Vapor pressure (mm Hg) (VPm from Equation B-4 above)
                              Temperature (Kelvin (K); temperature in °C plus 273, or 298 for 25 °C)
        See Appendix D, Section D.2. 1 for more discussion of the evaporation rate equation.  Equation B-7
is derived from Equation D- 1 .

        Worst-case consequence distances to the toxic endpoint may be estimated from the release rate using
the tables and instructions presented in Chapter 4.
April 15, 1999
                                               B - 12

-------
                        APPENDIX C




                  FLAMMABLE SUBSTANCES
April 15, 1999

-------
APPENDIX C    FLAMMABLE SUBSTANCES

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

        For a worst-case release of flammable gases and volatile flammable liquids, the release rate is not
considered. The total quantity of the flammable substance is assumed to form a vapor cloud. The entire
contents of the cloud is assumed to be within the flammability limits, and the cloud is assumed to explode.
For the worst-case, analysis, 10 percent of the flammable vapor in the cloud is assumed to participate in the
explosion (i.e., the yield factor is 0. 10). Consequence distances to an overpressure level of 1 pound per
square inch (psi) may be determined using the following equation, which is based on the TNT-equivalency
method:

                                         (               HCf } 1/3
                              D = 17  x   o.l x  Wfx -—J-\                          (C-l)
                                         ^             NLTNT)

where:         D      =      Distance to overpressure of 1 psi (meters)
               Wf    =      Weight of flammable substance (kilograms or pounds/2.2)
               Hcf    =      Heat of combustion of flammable substance (kilojoules per kilogram)
                             (listed in Exhibit C-l)
               HCTNT  =      Heat of explosion of trinitrotoluene (TNT) (4,680 kilojoules per kilogram)

        The factor  17 is a constant for damages associated with  1.0 psi overpressures. The factor 0. 1
        represents an explosion efficiency of 10 percent.  To convert distances from meters to miles, multiply
        by 0.00062.

        Alternatively, use the following equation for quantity in pounds and distance in miles:

                                                             HCf
                           D   =  0.0081  x   o.l  x  w,,  x - f—
                            mi                        Ib
where:         Dmi    =       Distance to overpressure of 1 psi (miles)
               Wlb    =       Weight of flammable substance (pounds)

        These equations were used to derive Reference Table 13 for worst-case distances to the overpressure
endpoint (1 psi) for vapor cloud explosions.

        C.2    Mixtures of Flammable Substances

        For a mixture of flammable substances, you may estimate the heat of combustion of the mixture from
the heats of combustion of the components of the mixture using the equation below and then use the equation
given in the previous section of this appendix to determine the vapor cloud explosion distance. The heat of
combustion of the mixture may be estimated as follows:
April 15, 1999

-------
Appendix C
Flammable Substances
                                        w
                               HCm  = -^
                                  m     W,
                                          ^
                               HC  +  -
                                   x    W,
                                HC,,
(C-3)
where:
HCm
Wx
wm
HCX
wy
HCy
Heat of combustion of mixture (kilojoules per kilogram)
Weight of component "X" in mixture (kilograms or pounds/2.2)
Total weight of mixture (kilograms or pounds/2.2)
Heat of combustion of component "X" (kilojoules per kilogram)
Weight of component "Y" in mixture (kilograms or pounds/2.2)
Heat of combustion of component "Y" (kilojoules per kilogram)
        Heats of combustion for regulated flammable substances are listed in Exhibit C-1 in the next section
(Section C.3) of this appendix.

        C.3    Data for Flammable Substances

        The exhibits in this section of Appendix C provide the data needed to carry out the calculations for
regulated flammable substances using the methods presented in the text of this guidance. Exhibit C-l
presents heat of combustion data for all regulated flammable substances, Exhibit C-2 presents additional data
for flammable gases, and Exhibit C-3 presents additional data for flammable liquids.  The heats of
combustion in Exhibit C-l and the data used to develop the factors in Exhibits C-2 and C-3 are primarily
from Design Institute for Physical Property Data, American Institute of Chemical Engineers, Physical and
Thermodynamic Properties of Pure Chemicals, Data Compilation. The derivation of the factors presented
in Exhibits C-2 and C-3 is discussed in Appendix D.
April 15, 1999
                                              C-2

-------
                                    Exhibit C-l
                    Heats of Combustion for Flammable Substances
CAS No.
75-07-0
74-86-2
598-73-2
106-99-0
106-97-8
25167-67-3
590-18-1
624-64-6
106-98-9
107-01-7
463-58-1
7791-21-1
590-21-6
557-98-2
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
Chemical Name
Acetaldehyde
Acetylene [Ethyne]
Bromotrifluoroethylene [Ethene, bromotrifluoro-]
1,3 -Butadiene
Butane
Butene
2-Butene-cis
2-Butene-trans [2-Butene, (E)]
1 -Butene
2-Butene
Carbon oxysulfide [Carbon oxide sulfide (COS)]
Chlorine monoxide [Chlorine oxide]
1-Chloropropylene [1-Propene, 1-chloro-]
2-Chloropropylene [1-Propene, 2-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]
Physical
State
at 25° C
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Liquid
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Gas
Heat of
Combustion
(kjoule/kg)
25,072
48,222
1,967
44,548
45,719
45,200*
45,171
45,069
45,292
45,100*
9,126
1,011*
23,000*
22,999
21,064
46,560
8,225
11,484
35,813
45,051
47,509
45,565
35,210
19,917
47,145
April 15, 1999
                                       C-3

-------
                                  Exhibit C-l (continued)
CAS No.
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
Chemical Name
Ethyl ether [Ethane, l,l'-oxybis-]
Ethyl mercaptan [Ethanethiol]
Ethyl nitrite [Nitrous acid, ethyl ester]
Hydrogen
Isobutane [Propane, 2-methyl]
Isopentane [Butane, 2-methyl-]
Isoprene [1,3 -Butadiene, 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-Pentadiene
Pentane
1-Pentene
2-Pentene, (E)-
2-Pentene, (Z)-
Propadiene [1,2-Propadiene]
Propane
Propylene [1-Propene]
Propyne [1-Propyne]
Silane
Physical
State
at 25° C
Liquid
Liquid
Gas
Gas
Gas
Liquid
Liquid
Liquid
Liquid
Gas
Gas
Gas
Liquid
Gas
Liquid
Gas
Liquid
Liquid
Liquid
Liquid
Liquid
Gas
Gas
Gas
Gas
Gas
Heat of
Combustion
(kjoule/kg)
33,775
27,948
18,000
119,950
45,576
44,911
43,809
36,484
23,720
50,029
31,396
44,559
44,414
28,835
15,335
44,985
43,834
44,697
44,625
44,458
44,520
46,332
46,333
45,762
46,165
44,307
April 15, 1999
                                            C-4

-------
                                   Exhibit C-l (continued)
CAS No.
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
Chemical Name
Tetrafluoroethylene [Ethene, tetrafluoro-]
Tetramethylsilane [Silane, tetramethyl-]
Trichlorosilane [Silane, trichloro-]
Trifluorochloroethylene [Ethene, chlorotrifluoro-]
Trimethylamine [Methanamine, N,N-dimethyl-]
Vinyl acetylene [l-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-]
Physical
State
at 25° C
Gas
Liquid
Liquid
Gas
Gas
Gas
Gas
Liquid
Gas
Liquid
Gas
Gas
Heat of
Combustion
(kjoule/kg)
1,284
41,712
3,754
1,837
37,978
45,357
18,848
32,909
2,195
10,354
10,807
30,549
' Estimated heat of combustion
April 15, 1999
                                             C-5

-------
                                                     Exhibit C-2
                                              Data for Flammable Gases
CAS
Number
75-07-0
74-86-2
598-73-2
106-99-0
106-97-8
25167-67-3
590-18-1
624-64-6
106-98-9
107-01-7
463-58-1
7791-21-1
557-98-2
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
Chemical Name
Acetaldehyde
Acetylene
Bromotrifluoroethylene
1,3-Butadiene
Butane
Butene
2-Butene-cis
2-Butene-trans
1 -Butene
2-Butene
Carbon oxysulfide
Chlorine monoxide
2-Chloropropylene
Cyanogen
Cyclopropane
Dichlorosilane
Difluoroethane
Dimethylamine
2,2-Dimethylpropane
Ethane
Ethyl acetylene
Ethvlamine
Molecular
Weight
44.05
26.04
160.92
54.09
58.12
56.11
56.11
56.11
56.11
56.11
60.08
86.91
76.53
52.04
42.08
101.01
66.05
45.08
72.15
30.07
54.09
45.08
Ratio of
Specific
Heats
1.18
1.23
1.11
1.12
1.09
1.10
1.12
1.11
1.11
1.10
1.25
1.21
1.12
1.17
1.18
1.16
1.14
1.14
1.07
1.19
1.11
1.13
Flammability
Limits (Vol %)
Lower
(LFL)
4.0
2.5
C
2.0
1.5
1.7
1.6
1.8
1.6
1.7
12.0
23.5
4.5
6.0
2.4
4.0
3.7
2.8
1.4
2.9
2.0
3.5
Upper
UFL
60.0
80.0
37.0
11.5
9.0
9.5
9.7
9.7
9.3
9.7
29.0
NA
16.0
32.0
10.4
96.0
18.0
14.4
7.5
13.0
32.9
14.0
LFL
(mg/L)
72
27
C
44
36
39
37
41
37
39
290
830
140
130
41
160
100
52
41
36
44
64
Gas
Factor
(GF)S
22
17
41C
24
25
24
24
24
24
24
26
31
29
24
22
33
27
22
27
18
24
22
Liquid
Factor
Boiling
(LFB)
0.11
0.12
0.25C
0.14
0.14
0.14
0.14
0.14
0.14
0.14
0.18
0.19
0.16
0.15
0.13
0.20
0.17
0.12
0.16
0.14
0.13
0.12
Density
Factor
(Boiling)
(DF)
0.62
0.78
0.29C
0.75
0.81
0.77
0.76
0.77
0.78
0.77
0.41
NA
0.54
0.51
0.72
0.40
0.48
0.73
0.80
0.89
0.73
0.71
Reference
Table3
Dense
Buoyant
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Pool Fire
Factor
(PFF)
2.7
4.8
0.42C
5.5
5.9
5.6
5.6
5.6
5.7
5.6
1.3
0.15
3.3
2.5
5.4
1.3
1.6
3.7
6.4
5.4
5.4
3.6
Flash
Fraction
Factor
(FFF/
0.018
0.23f
0.15C
0.15
0.15
0.14
0.11
0.12
0.17
0.12
0.29
NA
0.011
0.40
0.23
0.084
0.23
0.090
0.11
0.75
0.091
0.040
April 15, 1999
                                                        C-6

-------
                                                  Exhibit C-2 (continued)
CAS
Number
75-00-3
74-85-1
109-95-5
1333-74-0
75-28-5
74-82-8
74-89-5
563-45-1
115-10-6
115-11-7
463-49-0
74-98-6
115-07-1
74-99-7
7803-62-5
116-14-3
79-38-9
75-50-3
689-97-4
75-01-4
75-02-5
75-38-7
Chemical Name
Ethyl chloride
Ethylene
Ethyl nitrite
Hydrogen
Isobutane
Methane
Methylamine
3 -Methyl- 1-butene
Methyl ether
2-Methylpropene
Propadiene
Propane
Propylene
Propyne
Silane
Tetrafluoroethylene
Trifluorochloroethylene
Trimethylamine
Vinyl acetylene
Vinyl chloride
Vinyl fluoride
Vinvlidene fluoride
Molecular
Weight
64.51
28.05
75.07
2.02
58.12
16.04
31.06
70.13
46.07
56.11
40.07
44.10
42.08
40.07
32.12
100.02
116.47
59.11
52.08
62.50
46.04
64.04
Ratio of
Specific
Heats
1.15
1.24
1.30
1.41
1.09
1.30
1.19
1.08
1.15
1.10
1.16
1.13
1.15
1.16
1.24
1.12
1.11
1.10
1.13
1.18
1.20
1.16
Flammability
Limits (Vol %)
Lower
(LFL)
3.8
2.7
4.0
4.0
1.8
5.0
4.9
1.5
3.3
1.8
2.1
2.0
2.0
1.7
C
11.0
8.4
2.0
2.2
3.6
2.6
5.5
Upper
UFL
15.4
36.0
50.0
75.0
8.4
15.0
20.7
9.1
27.3
8.8
2.1
9.5
11.0
39.9
C
60.0
38.7
11.6
31.7
33.0
21.7
21.3
LFL
(mg/L)
100
31
120
3.3
43
33
62
43
64
41
34
36
34
28
C
450
400
48
47
92
49
140
Gas
Factor
(GF)S
27
18
30
5.0
25
14
19
26
22
24
21
22
21
21
19 c
33
35
25
24
26
23
27
Liquid
Factor
Boiling
(LFB)
0.15
0.14
0.16
e
0.15
0.15
0.10
0.15
0.14
0.14
0.13
0.14
0.14
0.12
e
0.29
0.26
0.14
0.13
0.16
0.17
0.22
Density
Factor
(Boiling)
(DF)
0.53
0.85
0.54
e
0.82
1.1
0.70
0.77
0.66
0.77
0.73
0.83
0.79
0.72
e
0.32
0.33
0.74
0.69
0.50
0.57
0.42
Reference
Table3
Dense
Buoyant
Dense
d
Dense
Buoyant
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Pool Fire
Factor
(PFF)
2.6
5.4
2.0
e
6.0
5.6
2.7
6.0
3.4
5.7
5.2
5.7
5.5
4.9
e
0.25
0.34
4.8
5.4
2.4
0.28
1.8
Flash
Fraction
Factor
(FFF/
0.053
0.63f
NA
NA
0.23
0.87f
0.12
0.030
0.22
0.18
0.20
0.38
0.35
0.18
0.41f
0.69
0.27
0.12
0.086
0.14
0.37
0.50
April 15, 1999
                                                            C-7

-------
                                                             Exhibit C-2 (continued)
CAS
Number
107-25-5
Chemical Name
Vinyl methyl ether
Molecular
Weight
58.08
Ratio of
Specific
Heats
1.12
Flammability
Limits (Vol %)
Lower
(LFL)
2.6
Upper
UFL
39.0
LFL
(mg/L)
62
Gas
Factor
(GF)S
25
Liquid
Factor
Boiling
(LFB)
0.17
Density
Factor
(Boiling)
(DF)
0.57
Reference
Table3
Dense
Pool Fire
Factor
(PFF)
3.7
Flash
Fraction
Factor
(FFF/
0.093
Notes:

NA: Data not available
a "Buoyant" in the Reference Table column refers to the tables for neutrally buoyant gases and vapors; "Dense" refers to the tables for dense gases and vapors. See
Appendix D, Section D.4.4, for more information on the choice of reference tables.
  Gases that are lighter than air may behave as dense gases upon release if liquefied under pressure or cold; consider the conditions of release when choosing the
appropriate table.
0 Reported to be spontaneously combustible.
  Much lighter than air; table of distances for neutrally buoyant gases not appropriate.
e Pool formation unlikely.
f Calculated at 298 K (25 °C) with the following exceptions:
         Acetylene factor at 250 K as reported in TNO, Methods for the Calculation of the Physical Effects of the Escape of Dangerous Material (1980).
         Ethylene factor calculated at critical temperature, 282 K.
         Methane factor calculated at critical temperature, 191 K.
         Silane factor calculated at critical temperature, 270 K.
8 Use GF for gas leaks under choked (maximum) flow conditions.
April 15, 1999

-------
                                                                 Exhibit C-3
                                                       Data for Flammable Liquids
CAS
Number
590-21-6
60-29-7
75-08-1
78-78-4
78-79-5
75-31-0
75-29-6
563-46-2
107-31-3
504-60-9
109-66-0
109-67-1
646-04-8
627-20-3
75-76-3
10025-78-2
109-92-2
75-35-4
Chemical Name
1 -Chloropropylene
Ethyl ether
Ethyl mercaptan
Isopentane
Isoprene
Isopropylamine
Isopropyl chloride
2-Methyl-l-butene
Methyl formate
1,3-Pentadiene
Pentane
1-Pentene
2-Pentene, (E)-
2-Pentene, (Z)-
Tetramethylsilane
Trichlorosilane
Vinyl ethyl ether
Vinylidene chloride
Molecular
Weight
76.53
74.12
62.14
72.15
68.12
59.11
78.54
70.13
60.05
68.12
72.15
70.13
70.13
70.13
88.23
135.45
72.11
96.94
Flammabiliry Limit
(Vol%)
Lower
(LFL)
4.5
1.9
2.8
1.4
2.0
2.0
2.8
1.4
5.9
1.6
1.3
1.5
1.4
1.4
1.5
1.2
1.7
7.3
Upper
(UFL)
16.0
48.0
18.0
7.6
9.0
10.4
10.7
9.6
20.0
13.1
8.0
8.7
10.6
10.6
NA
90.5
28.0
NA
LFL
(mg/L)
140
57
71
41
56
48
90
40
140
44
38
43
40
40
54
66
50
290
Liquid Factors
Ambient
(LFA)
0.11
0.11
0.10
0.14
0.11
0.10
0.11
0.12
0.10
0.077
0.10
0.13
0.10
0.10
0.17
0.18
0.10
0.15
Boiling
(LFB)
0.15
0.15
0.13
0.15
0.14
0.13
0.16
0.15
0.13
0.14
0.15
0.15
0.15
0.15
0.17
0.23
0.15
0.18
Density
Factor
0.52
0.69
0.58
0.79
0.72
0.71
0.57
0.75
0.50
0.72
0.78
0.77
0.76
0.75
0.59
0.37
0.65
0.44
Liquid Leak
Factor
(LLF)a
45
34
40
30
32
33
41
31
46
33
30
31
31
31
40
64
36
54
Reference
Table"
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Dense
Pool Fire
Factor
(PFF)
3.2
4.3
3.3
6.1
5.5
4.1
3.1
5.8
1.8
5.3
5.8
5.8
5.6
5.6
6.3
0.68
4.2
1.6
Notes:
NA: Data not available.
a Use the LLF only for leaks from tanks at atmospheric pressure.
b "Dense" in the Reference Table column refers to the tables for dense gases and vapors.
reference tables.
See Appendix D, Section D.4.4, for more information on the choice of
April 15, 1999
                                                                     C-9

-------
                         APPENDIX D




                  TECHNICAL BACKGROUND
April 15, 1999

-------
APPENDIX D     TECHNICAL BACKGROUND

        D.I    Worst-Case Release Rate for Gases

               D.I.I  Unmitigated Release

        The assumption that the total quantity of toxic gas is released in 10 minutes is the same assumption
used in EPA's Technical Guidance for Hazards Analysis (1987).

               D.I.2  Gaseous Release Inside Building

        The mitigation factor for gaseous release inside a building is based on a document entitled, Risk
Mitigation in Land Use Planning: Indoor Releases of Toxic Gases, by S.R. Porter.  This paper presented
three release scenarios and discussed the mitigating effects that would occur in a building with a volume of
1,000 cubic meters at three different building air exchange rates. There is a concern that a building may not
be able to withstand the pressures of a very large release.  However, this paper indicated that release rates of
at least 2,000 pounds per minute could be withstood by a building.

        Analyzing the data in this paper several ways, the value of 55 percent emerged as representing the
mitigation that could occur for a release scenario into a building. Data are provided on the maximum release
rate in a building and the maximum release rate from a building. Making this direct comparison at the lower
maximum release rate  (3.36 kg/s) gave a release rate from the building of 55 percent of the release rate into
the building. Using information provided on another maximum release rate (10.9 kg/min) and accounting for
the time for the release to accumulate in the building, approximately 55 percent emerged again.

        The choice of building ventilation rates affects the results. The paper presented mitigation for three
different ventilation rates, 0.5, 3, and 10 air changes per hour. A ventilation rate of 0.5 changes per hour is
representative of specially designed, "gas-tight" buildings, based on the Porter reference.  EPA decided that
this ventilation rate was appropriate for this analysis. A mitigation factor of 55 percent may be used in the
event of a gaseous release which does not destroy the building into which it is released. This factor may
overstate the mitigation provided by a building with a higher ventilation rate.

        For releases of ammonia, chlorine, and sulfur dioxide, factors specific to the chemicals, the
conditions of the release, and building ventilation rates have been developed to estimate mitigation of releases
in buildings. For information on these factors and estimation of mitigated release rates, see Backup
Information for the Hazard Assessments in the RMP Offsite Consequence Analysis Guidance, the
Guidance for Wastewater Treatment Facilities and the Guidance for Ammonia Refrigeration -Anhydrous
Ammonia, Aqueous Ammonia, Chlorine and Sulfur Dioxide.  See also the industry-specific guidance
documents for  ammonia refrigeration and POTWs.

        D.2    Worst-Case Release Rate for Liquids

               D.2.1  Evaporation Rate Equation

        The equation for estimating the evaporation rate of a liquid from a pool is from the Technical
Guidance for Hazards Analysis, Appendix G.  The same assumptions are made for determination of


April 15, 1999

-------
Appendix D
Technical Background _

maximum pool area (i.e., the pool is assumed to be 1 centimeter (0.033 feet) deep). The evaporation rate
equation has been modified to include a different mass transfer coefficient for water, the reference compound.
For this document, a value of 0.67 centimeters per second is used as the mass  transfer coefficient, instead of
the value of 0.24 cited in the Technical Guidance for Hazards Analysis.  The value of 0.67 is based on
Donald MacKay and Ronald S. Matsugu, "Evaporation Rates of Liquid Hydrocarbon Spills on Land and
Water," Canadian Journal of Chemical Engineering, August  1973, p. 434. The evaporation equation
becomes:
                                  0.284 x  U°™ x MW   x  A  x  VP
                                               82.05 x  T                                 *D~1*

where:         QR     =      Evaporation rate (pounds per minute)
               U      =      Wind speed (meters per second)
               MW    =      Molecular weight (given in Exhibits B- 1 and B-2, Appendix B, for toxic
                              substances and Exhibits C-2 and C-3, Appendix C, for flammable
                              substances)
               A       =      Surface area of pool formed by the entire quantity of the mixture (square
                              feet) (determined as described in Section 3.2.2 of the text)
               VP     =      Vapor pressure (mm Hg)
               T       =      Temperature of released substance (Kelvin (K); temperature in °C plus 273,
                              or 298 for 25 °C)

               D.2.2  Factors for Evaporation Rate Estimates

        Liquid Factors.  The liquid factors, Liquid Factor Ambient (LFA) and Liquid Factor Boiling (LFB),
used to estimate the evaporation rate from a liquid pool (see Section 3.2 of this guidance document), are
derived as described in the Technical Guidance for Hazards Analysis, Appendix G, with the following
differences:

        •       The mass transfer coefficient of water is assumed to be 0.67, as discussed above; the value
               of the factor that includes conversion factors, the mass transfer coefficient for water, and the
               molecular weight of water to the one-third power, given  as 0. 106 in the Technical Guidance
               is 0.284 in this guidance.

        •       Density of all substances was assumed to be the density  of water in the Technical Guidance;
               the density was included in the liquid factors. For this guidance document, density is not
               included in the LFA and LFB values presented in the tables; instead, a separate Density
               Factor (DF) (discussed below) is provided to be used in the evaporation rate estimation.

        With these modifications, the LFA is:


                                 TE,A    0.284  x MW2'3 x VP
                                 LFA = -                           (D-2)
                                               82.05  x 298                               v     '

where:         MW           =       Molecular weight

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                                                                                        Appendix D
                                                                               Technical Background
LFB is:
               VP            =       Vapor pressure at ambient temperature (mm Hg)
               298 K (25 °C)  =       Ambient temperature and temperature of released substance
                                 LFB  -  0.284 x MW»  x 760
                                               82.05  x BP                               ^    '
where:         MW    =      Molecular weight
               760     =      Vapor pressure at boiling temperature (mm Hg)
               BP     =      Boiling point (K)

        LFA and LFB values were developed for all toxic and flammable regulated liquids, and LFB values,
to be used for analysis of gases liquefied by refrigeration, were developed for toxic and flammable gases.

        Density Factor.  Because some of the regulated liquids have densities very different from that of
water, the density of each substance was used to  develop a Density Factor (DF) for the determination of
maximum pool area for the evaporation rate estimation.  DF values were developed for toxic and flammable
liquids at ambient temperature and for toxic and  flammable gases at their boiling points.  The density factor
is:

                                        DF = -                                (D-4)
                                               d x 0.033                                l    '

where:         DF     =      Density factor  (l/(lbs/ft2))
               d       =      Density of the  substance in pounds per cubic foot
               0.033   =      Depth of pool for maximum area (feet)

        Temperature Correction Factors. Temperature correction factors were developed for toxic liquids
released at temperatures  above 25 °C, the temperature used for development of the LFAs.  The temperature
correction factors are based on vapor pressures calculated from the coefficients provided in Physical and
Thermodynamic Properties of Pure Chemicals,  Data Compilation, developed by the Design Institute for
Physical Property Data (DIPPR), American Institute of Chemical Engineers. The factors are calculated as
follows:

                                              VPT  x 298
                                    TCFT = -                                   fD-51
where:         TCFT   =      Temperature Correction Factor at temperature T
               VPT    =      Vapor pressure at temperature T
               ^298   =      Vapor pressure at 298 K
               T      =      Temperature (K) of released substance

Factors were developed at intervals of 5 °C for temperatures up to 50 °C.

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Appendix D
Technical Background	

        No correction factor was deemed necessary for changes in the density of the regulated toxic liquids
with changes in temperature, although the density could affect the pool area and release rate estimates.
Analysis of the temperature dependence of the density of these liquids indicated that the changes in density
with temperature were very small compared to the changes in vapor pressure with temperature.

                D.2.3  Common Water Solutions and Oleum

        Water solutions of regulated toxic substances must be analyzed somewhat differently from pure toxic
liquids. Except for solutions of relatively low concentration, the evaporation rate varies with the
concentration of the solution.  At one specific concentration, the composition of the liquid does not change as
evaporation occurs. For concentrated solutions of volatile substances, the evaporation rate from a pool may
decrease, very rapidly in some cases, as the toxic substance volatilizes and its concentration in the pool
decreases. To analyze these changes, EPA used spreadsheets to estimate the vapor pressure, concentration,
and release rate at various time intervals for regulated toxic substances in water solution evaporating from
pools.  In addition to the spreadsheet analysis, EPA used the ALOHA model with an additional step-function
feature (not available in the public version). With this step-function feature, changes in the release rate could
be incorporated and the effects of these changes on the consequence distance analyzed. The results of the
spreadsheet calculations and the model were found to be in good agreement. The distance results obtained
from the spreadsheet analysis and the model for various solutions were compared with the results from
various time averages to examine the sensitivity of the results. An averaging time of 10 minutes was found to
give reasonable agreement with the step-function model for most substances at various concentrations. The
spreadsheet analysis also indicated that the first 10 minutes of evaporation was the most important, and the
evaporation rate in the first 10 minutes likely could be used to estimate the distance to the endpoint.

        Oleum is a solution of sulfur trioxide in sulfuric acid.  Sulfur trioxide  evaporating from oleum
exhibits release characteristics similar to those of toxic substances evaporating from water solutions.
Analysis of oleum releases, therefore, was carried out in the same  way as for water solutions.

        NOAA developed a computerized calculation method to estimate partial vapor pressures and release
rates for regulated toxic substance in solution as a function of concentration, based on vapor pressure data
from Perry's  Chemical Engineers' Handbook and other sources.  Using this method and spreadsheet
calculations, EPA estimated partial vapor pressures and evaporation rates at one-minute intervals over 10
minutes for solutions of various concentrations. The 10-minute time period was chosen based on the
ALOHA results  and other calculations.  For each one-minute interval, EPA estimated the concentration of the
solution based on the quantity evaporated in the previous interval  and estimated the partial vapor pressure
based on the concentration. These estimated vapor pressures were used to calculate an average vapor
pressure over the 10-minute period; this average vapor pressure was used to derive Liquid Factor Ambient
(LFA) values, as described above for liquids. Use of these factors is intended to give an evaporation rate that
accounts for the  decrease in evaporation rate expected to take place as the solution evaporates.

        Density Factors (DF) were developed for solutions of various concentrations from data m Perry's
Chemical Engineers' Handbook and other sources, as discussed above for liquids.

        Because solutions do not have defined boiling points, EPA did not develop  Liquid Factor Boiling
(LFB) values for solutions. As a simple and conservative approach, the quantity of a regulated substance in a
solution at an elevated temperatures is treated as a pure substance. The LFB for the pure substance, or the

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                                                                                          Appendix D
	Technical Background

LFA and a temperature correction factor, is used to estimate the initial evaporation rate of the regulated
substance from the solution. Only the first 10 minutes of evaporation are considered, as for solutions at
ambient temperatures, because the release rate would decrease rapidly as the substance evaporates and the
concentration in the solution decreases. This approach will likely give an overestimate of the release rate and
of the consequence distance.

                D.2.4  Releases Inside Buildings

        If a liquid is released inside a building, its release to the outside air will be mitigated in two ways.
First, the evaporation rate of the liquid may be much lower inside a building than outside. This is due to wind
speed, which directly affects the evaporation rate.  The second mitigating factor is that the building provides
resistance to discharge of contaminated air to the outdoors.

        In this method, a conservative wind speed, U, of 0.1 meter per second (m/s) was assumed in the
building.  (See end of text for a justification of this wind speed.)  For a release outdoors in a worst-case
scenario, U is set to 1.5 m/s, and for an alternative scenario, U is set to 3 m/s. The evaporation rate equation
is:

                                 QR =  f/°'78  x (LFA,  LFB}  x  A                           (D-6)

where:          QR    =       Release rate (pounds per minute (Ibs/min))
                U      =       Wind speed (meters per second (m/s))
               LFA   =       Liquid Factor Ambient
               LFB   =       Liquid Factor Boiling
               A      =       Area of pool (square feet (ft2))

As can be seen, if U inside a building is only 0.1, then the evaporation rate inside a building will be much
lower than a corresponding evaporation rate outside (assuming the temperature is the same). The rate will
only be (0.1/1.5)078, about 12 percent of the rate for a worst case, and (0.1/3)078, about seven percent of the
rate for an alternative case.

        The evaporated liquid mixes with and contaminates the air in the building. What EPA is ultimately
interested in is the rate at which this contaminated air exits the building. In order to calculate the release of
contaminated air outside the building, EPA adapted a method from an UK Health and Safety Executive paper
entitled, Risk Mitigation in Land Use Planning: Indoor Releases of Toxic Gases, by S.R. Porter. EPA
assumed that the time for complete evaporation of the liquid pool was one hour. The rate at which
contaminated air was released from the building during liquid evaporation (based on the paper) was assumed
to be equal to the evaporation rate plus the building ventilation rate (no pressure buildup in building). The
building ventilation rate was set equal to 0.5 air changes per hour. This ventilation rate is representative of a
specially designed, "gas-tight" building. (The mitigation factor developed based on this type of building
would overstate the mitigation provided by a building with higher ventilation rates.)  EPA used a building
with a volume of 1,000 cubic meters (m3) and a floor area of 200  m2 (2,152 ft2) as an example for this
analysis. EPA assumed that the liquid pool would cover the entire building floor, representing a conservative
scenario.
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Appendix D
Technical Background	

        To provide a conservative estimate, EPA calculated the evaporation rate for a spill of a volatile
liquid, carbon disulfide (CS2), under ambient conditions inside the building:

                    QR = 0.1078 x 0.075 x 2,152 = 26.8 pounds per minute (Ibs/min)

        Next, this evaporation rate was converted to cubic meters per minute (mVmin) using the ideal gas
law (the molecular weight of CS2 is 76.1):

        26.8 Ibs/min x 454 grams per pound (g/lb) x 1 mole CS/76.1 g x 0.0224 mVmole = 3.58 mVmin.

        The ventilation rate of the building is 0.5 changes per hour, which equals 500 m3 per hour, or 8.33
mVmin. Therefore, during evaporation, contaminated air is leaving the building at a rate of 8.33 + 3.58, or
11.9m3/min.

        EPA used an iterative calculation for carbon disulfide leaving a building using the above calculated
parameters.  During the first minute of evaporation, 26.8 Ibs of pure carbon disulfide evaporates, and EPA
assumed this evenly disperses through the building so that the concentration of CS2  in the building air is
0.0268 lbs/m3 (assuming 1000 m3 volume in the building).  Contaminated air is exiting the building at a rate
of 11.9 mVmin, so EPA deduced that 11.9 x 0.0268 = 0.319 Ibs of carbon disulfide exit the building in the
first minute, leaving 26.5 Ibs still evenly dispersed inside. Since this release occurs  over one minute, the
release rate of the carbon disulfide to the outside is 0.319 Ibs/min. During the second minute, another 26.8
Ibs of pure carbon disulfide evaporates and disperses, so that the building now contains 26.8 + 26.5 = 53.3
Ibs of carbon disulfide, or 0.0533 lbs/m3.  Contaminated air is still exiting the building at a rate of 11.9
m3/min, so 11.9 x 0.05328 = 0.634 Ibs of carbon disulfide are released, leaving 52.6 Ibs inside. Again, this
release occurs over one minute so that the rate of carbon disulfide exiting the building in terms of
contaminated air is 0.634 Ibs/min. EPA continued to perform this estimation over a period of one hour. The
rate of release of carbon disulfide exiting the building in the contaminated air at the  sixty minute mark is 13.7
Ibs/min. This represents the maximum rate of carbon disulfide leaving the building. After all of the carbon
disulfide is evaporated, there is a drop in the concentration of carbon disulfide in the contaminated air leaving
the building because the evaporation of carbon disulfide no longer contributes to the overall contamination of
the air.

        Note that if the same size pool of carbon disulfide formed outside, the release rate for a worst-case
scenario would be:

        QR= 1.5078 x  0.075 x 2,152 = 221 Ibs/min.

and for an alternative case:

        QR = 3078 x 0.075 x 2,152 = 380 Ibs/min.

        The maximum release rate of carbon disulfide in the contaminated building air, assuming a 1,000 m3
building with a building exchange rate of 0.5 air changes per hour, was only about 6 percent  (13.7^-221
Ibs/min x 100) of the worst-case scenario rate, and only about 3.6 percent (13.7 + 380 Ibs/min x 100) of the
alternative scenario rate.  EPA set an overall building mitigation factor equal to 10 percent and five percent,
respectively, in order to be conservative. Please note that (at a constant ventilation rate of 0.5 changes per

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                                                                                       Appendix D
	Technical Background

hour) as the size of the building increases, the maximum rate of contaminated air leaving the building will
decrease, although only slightly, because of the balancing effect of building volume and ventilation rate.
Obviously, a higher ventilation rate will yield a higher maximum release rate of contaminated air from the
building.

        For a release inside a building, EPA assumed a building air velocity of 0.1 m/s.  This conservative
value was derived by setting the size of the ventilation fan equal to 1.0m2. This fan is exchanging air from
the building with the outside at a rate of 0.5 changes per hour.  For a 1,000 m3 building, this value becomes
500 m3/hour, or 0.14 m3/s. Dividing 0.14 m3/s by the area of the fan yields a velocity of 0.14 m/s, which was
rounded down to 0.1 m/s.

        D.3    Toxic Endpoints

        The toxic endpoints for regulated toxic substances, which are specified in the RMP Rule, are
presented in Appendix B, Exhibits B-l, B-2, and B-3. The endpoints were chosen as follows, in order of
preference:

        (1)     Emergency Response Planning Guideline 2 (ERPG-2), developed by the American Industrial
               Hygiene Association, if available;

        (2)     Level of Concern (LOG) derived for extremely hazardous substances (EHSs) regulated
               under section 302 of the Emergency Planning and Community Right-to-Know Act (EPCRA)
               (see the Technical Guidance for Hazards Analysis for more information on LOCs); the
               LOG for EHSs is based on:

                       One-tenth of the Immediately Dangerous to Life and Health (IDLH) level,
                       developed by the National Institute of Occupational Safety and Health (NIOSH),
                       using IDLH values developed before 1994,

                       or, if no IDLH value is available,

                       One-tenth of an estimated IDLH derived from toxicity data; the IDLH is estimated
                       as described in Appendix D of the Technical Guidance for Hazards Analysis.

                       Note that the LOCs were not updated using IDLHs published in 1994 and later,
                       because NIOSH revised its methodology for the IDLHs. The EHS LOCs based on
                       earlier IDLHs were reviewed by EPA's Science Advisory Board, and EPA decided
                       to retain the methodology that was reviewed.

        ERPG-2 is defined as the maximum airborne concentration below which it is believed nearly all
individuals could be exposed for up to one hour without experiencing or developing irreversible or other
serious health effects or symptoms that could impair an individual's ability to take protective action.

        IDLH (pre-1994) concentrations were defined in the NIOSH Pocket Guide to Chemical Hazards as
representing the maximum concentration from which, in the event of respirator failure, one could escape
within 30 minutes without a respirator and without experiencing any escape-impairing (e.g., severe eye

April 15, 1999                                    D - 7

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Appendix D
Technical Background	

irritation) or irreversible health effects. (As noted above, LOCs for EHSs were not updated to reflect 1994
and later IDLHs.)

        The estimated IDLH is derived from animal toxicity data, in order of preferred data, as follows:

        •      From median lethal concentration (LC50) (inhalation): 0.1 x LC50

        •      From lowest lethal concentration (LCLO) (inhalation):  1  x LCLO

        •      From median lethal dose (LD50) (oral):  0.01xLD50

        •      From lowest lethal dose (LDLO) (oral): 0.1 x LDLO

        The toxic endpoints based on LOCs for EHSs presented in the tables in Appendix B are, in some
cases, different from the LOCs listed in the Technical Guidance for Hazards Analysis, because some of the
LOCs were updated based on IDLHs that were published after the development of the LOCs (and before
1994) or on new or revised toxicity data.

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

               D.4.1  Neutrally Buoyant Gases

        Toxic Substances. Reference tables for distances to toxic endpoints for neutrally buoyant gases and
vapors were derived from the Gaussian model using the longitudinal dispersion coefficients based on work by
Beals (Guide to Local Diffusion of Air Pollutants, Technical Report 214. Scott Air Force Base, Illinois:
U.S. Air Force, Air Weather Service, 1971).  The reasons for using the Beals dispersion coefficients are
discussed below.

        Longitudinal dispersion  (dispersion in the along-wind direction) is generated mostly by vertical wind
shear.  Wind shear results from the tendency of the wind speed to assume a wind profile—the speed is lowest
next to the ground and increases  with height until it reaches an asymptotic value at approximately a few
hundred feet above the surface. To account for shear-driven dispersion, any  air dispersion model intended for
modeling short-duration releases must include either (a) a formulation that accounts, either implicitly or
explicitly, for the height-dependence of wind speed or (b) some type of parameterization that converts shear
effect into ox, the standard deviation function in the along-wind direction.

        Because the standard Gaussian formula does not incorporate ox (it includes only oy and oz, the
crosswind and horizontal functions), very few alternate ways to formulate ox have been proposed.  The
simplest method was proposed by Turner (Workbook of Atmospheric Dispersion Estimates, Report PB-191
482. Research Triangle Park, North Carolina: Office of Air Programs, U.S. Environmental Protection
Agency, 1970), who suggested simply setting ox equal to oy. Textbooks such as that by Pasquill and Smith
(Atmospheric Diffusion, 3rd ed.  New York: Halstead Press, 1983) describe  a well-known analytic model.
However, this model is more complex than a Gaussian model because according to it, dispersion depends on
wind shear and the vertical variation of the vertical diffusion coefficient.  Wilson (Along-wind Diffusion of
Source Transients, Atmospheric  Environment 15:489-495, 1981) proposed another method in which oxis


April 15, 1999                                      D - 8

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                                                                                        Appendix D
	Technical Background

determined as a function of wind shear, but in a form that can then be used in a Gaussian model. However, it
is now believed that Wilson's formulation gives ox values that are too large.

        To avoid the problems of the analytic method and Wilson's formulation, we chose to include a
formulation for ox derived from work by Beals (1971). We had three reasons for doing so. First, in terms of
magnitude, Beals' ox fell in the midrange of the alternative formulations that we reviewed. Second, Beals' ox
indirectly accounts for wind shear by using (unpublished) experimental data. Third, both the ALOHA and
DEGADIS models incorporate the Beals methodology.

        When a substance is dispersed downwind, the concentration in the air changes over time. To assess
the health effects of potential exposure to the substance, the average concentration of the substance over
some time period is determined. Averaging time is the time interval over which the instantaneous
concentration of the hazardous material in the vapor cloud is averaged. Averaging time should generally be
equal to or shorter than either the release duration or cloud duration and, if possible, should reflect the
exposure time associated with the toxic exposure guideline of interest. The exposure time associated with the
toxic endpoints specified under the RMP Rule include 30 minutes for the Immediately Dangerous to Life and
Health (IDLH) level and 60 minutes for the Emergency Response Planning Guideline (ERPG). For the
neutrally buoyant tables, the 10-minute release scenario was modeled using a 10-minute averaging time. The
60-minute release scenario was modeled using a 30-minute averaging time to be consistent with the 30-
minute exposure time associated with the IDLH. A 60-minute averaging time may have underpredicted
consequence distances and, therefore, was not used for development of the distance tables for this guidance.

        Cloud dispersion from a release of finite duration (10 and 60-minute releases) is calculated using an
equation specified in the NOAA publication ALOHA™ 5.0 Theoretical Description, Technical Memorandum
NOS ORCA 65, August 1992.

        Flammable Substances. The reference tables of distances for vapor cloud fires of neutrally buoyant
flammable substances were  derived using the same model as for toxic substances, as described above. The
endpoint for modeling was the lower flammability limit (LFL).  For flammable substances, an averaging time
of 0.1 minute (six seconds) was used, because fires are considered to be nearly instantaneous events.

        Distances of interest for flammable substances are generally much shorter than for toxic substance,
because the LFL concentrations are much larger than the toxic endpoints.  For the short distances found in
modeling the flammable substances, modeling results were found  to be the same for 10-minute and longer
releases; therefore, one table of distances for rural conditions and  one table for urban conditions, applicable
for both 10-minute and longer releases, were developed for flammable substances.

               D.4.2  Dense Gases

        Toxic Substances.  The reference tables for dense gases were developed using the widely accepted
SLAB model, developed by Lawrence Livermore National Laboratory.  SLAB solves conservation equations
of mass, momentum, energy, and species for continuous, finite duration, and instantaneous releases.  The
reference tables were based  on the  evaporating pool algorithm.

        For the reference tables were developed based on modeling releases of hydrogen chloride (HC1).  HC1
was chosen based on a SLAB modeling analysis of a range of dispersion behavior for releases of regulated

April 15, 1999                                     D - 9

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Appendix D
Technical Background	

dense gases or vapors with different molecular weights. This analysis showed that releases of HC1 generally
provided conservative results under a variety of stability/wind speed combinations, release rates, and toxic
endpoints.

        Similar to the modeling of neutrally buoyant plumes, the 10-minute release scenario of toxic
chemicals was modeled using a 10-minute averaging time.  The 60-minute release scenario was modeled
using a 30-minute averaging time to be consistent with the 30-minute exposure time associated with the
IDLH.

        For all dense gas tables, the reference height for the wind speed was 10 meters.  Relative humidity
was assumed to be 50 percent, and the ambient temperature was 25 °C. The source area was the smallest
value that still enabled the model to run for all release rates. The surface roughness factor was one meter for
urban scenarios and three centimeters for rural scenarios.

        Flammable Substances.  For the reference tables for dispersion of dense flammable gases and vapors,
for analysis of vapor cloud fires, the same model was used as for toxic substances, as described above, and
the same assumptions were made.  For the dispersion of flammable chemicals, averaging time should be very
small (i.e., no more than a few seconds), because flammable vapors need only be exposed to an ignition
source for a short period of time to initiate the  combustion process. Thus, both the  10-minute and 60-minute
reference tables for flammable substances use an averaging time of 10 seconds. The 10-minute and 60-
minute tables were combined for flammable substances because the modeling results were found to be the
same.

               DAS Chemical-Specific Reference Tables

        The chemical-specific reference tables of distances for ammonia, chlorine, and sulfur dioxide were
developed for EPA's risk management program guidance for ammonia refrigeration and for POTWs.  For
information on the chemical-specific modeling and development of the chemical-specific reference tables, see
Backup Information for the Hazard Assessments in the RMP Offsite Consequence Analysis Guidance, the
Guidance for Wastewater Treatment Facilities and the Guidance for Ammonia Refrigeration -Anhydrous
Ammonia, Aqueous Ammonia, Chlorine and Sulfur Dioxide.  See  also the industry-specific guidance
documents for ammonia refrigeration and POTWs.

        The modeling carried out for aqueous  ammonia also is applied in this guidance to ammonia released
as a neutrally buoyant plume in other situations.  The tables of distances derived from this modeling would
apply to evaporation of ammonia from a water solution, evaporation of ammonia liquefied by refrigeration, or
ammonia releases from the vapor space of a vessel, because the ammonia would behave  as a neutrally
buoyant plume (or possibly buoyant in some cases).

               D.4.4 Choice of Reference Table for Dispersion Distances

        Gases.  Exhibit B-l of Appendix B indicates whether the reference tables for neutrally buoyant or
dense gases should be used for each of the regulated toxic gases. Exhibit C-2, Appendix C, provides this
information for flammable gases.  The choice of reference table presented in these exhibits is based on the
molecular weight of the regulated substance compared to air; however, a number of factors that may cause a
substance with a molecular weight  similar to or smaller than the molecular weight of air to behave as a dense

April 15, 1999                                     D - 10

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                                                                                          Appendix D
	Technical Background

gas should be considered in selecting the appropriate table. For example, a cold gas may behave as a dense
gas, even if it is lighter than air at ambient temperature. Gases liquefied under pressure may be released as a
mixture of vapor and liquid droplets; because of presence of liquid mixed with the vapor, a gas that is lighter
than air may behave as a dense gas in such a release. A gas that polymerizes or forms hydrogen bonds (e.g.,
hydrogen fluoride) also may behave as a dense gas.

        Liquids and Solutions.  Exhibits B-2 and B-3, Appendix B, and Exhibit C-3, Appendix C, indicate
the reference table of distances to be used for each regulated liquid.  The methodology presented in this
guidance for consequence analysis for liquids and solutions assumes evaporation from a pool.  All of the
liquids regulated under CAA section 112(r) have molecular weights greater than the molecular weight of air;
therefore, their vapor would be heavier than air. However, because the vapor from a pool will mix with air as
it evaporates, the initial density of the vapor with respect to air may not in all cases indicate whether the vapor
released from a pool should be modeled as a dense gas or a neutrally buoyant gas.  If the rate of release from
the pool is relatively low, the vapor-air mixture that is generated may be neutrally buoyant even if the vapor is
denser than air, because the mixture may contain a relatively small fraction of the denser-than-air vapor; i.e.,
it may be mostly air.  This may be the case particularly for some of the regulated toxic liquids with relatively
low volatility. All of the regulated flammable substances have relatively high volatility; the reference tables
for dense gases are assumed to be appropriate for analyzing dispersion of these flammable liquids.

        To identify toxic liquids with molecular weight greater than air that might behave as neutrally
buoyant gases when evaporating from a pool, EPA used the ALOHA model for pool evaporation of a number
of substances with a range of molecular weights and vapor pressures.  Modeling was carried out for F
stability and wind speed 1.5 meters per second (worst-case conditions) and for D stability and wind speed 3.0
meters per second (alternative-case conditions). Pool spread to a depth of one centimeter was assumed.
Additional modeling was carried out for comparison assuming different pool areas and depths.  The
molecular weight-vapor pressure combinations at which ALOHA used the neutrally buoyant gas model were
used to develop the reference table choices given in Exhibit B-2 (for liquids) and B-3 (for solutions) in
Appendix B. The neutrally buoyant tables should generally give reasonable results for pool evaporation
under ambient conditions when indicated for liquids. At  elevated temperatures, however, evaporation rates
will be greater, and the dense gas tables should be used.

        The liquids for which the neutrally buoyant table is identified for the worst case probably can be
expected to behave as neutrally buoyant vapors when evaporating from pools under ambient conditions in
most situations, but there may be cases when they exhibit dense gas behavior. Other liquids, for which the
neutrally buoyant tables are not indicated for the worst case, might release neutrally buoyant vapors under
some conditions (e.g., relatively small pools, temperature not much above 25 °C).  Similarly, the liquids for
which the neutrally buoyant tables are indicated as appropriate for alternative scenario analysis probably can
be considered to behave as neutrally buoyant vapors under the alternative scenario conditions in most cases;
however, there may be cases where they will behave as dense gases, and there may be other liquids that in
some cases would exhibit neutrally buoyant behavior when evaporating. The reference table choices shown
in Exhibit B-2 are intended to reflect the most likely behavior of the substances; they will not predict
behavior of the listed substances evaporating under all conditions.
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Appendix D
Technical Background	

               DAS  Additional Modeling for Comparison

        Modeling was carried out for two worst-case examples and two alternative-case examples, using two
different models, for comparison with the results obtained from the methods and distance tables in this
guidance.  This modeling is discussed below.

        ALOHA Model. The Areal Locations of Hazardous Atmospheres (ALOHA) system was developed
jointly by NOAA and EPA. ALOHA Version 5.2.1 was used for the comparison modeling.  The parameters
for ALOHA modeling were the same as specified in this guidance document for worst-case and alternative
scenarios. The substances modeled are included in ALOHA's chemical database, so no chemical data were
entered for modeling. For consistency with the methodology used to develop the reference tables of distances,
a wind speed height of 10 meters was selected for ALOHA modeling.

        For all of the substances modeled, the direct source model was chosen for ALOHA modeling, and the
release rate estimated using the guidance methodology was entered as the release rate for ALOHA. ALOHA
selected the dense gas model to estimate the distances to the endpoints in all cases.

        WHAZAN Model. The World Bank Hazard Analysis (WHAZAN) system was developed by
Technica International in collaboration with the World Bank.  The 1988 version of WHAZAN was used for
the comparison modeling.  The parameters for atmospheric stability, wind speed, and ambient temperature
and humidity were the same as specified in this guidance document. For surface roughness, WHAZAN
requires entry of a "roughness parameter," rather than a height.  Based on the discussion of this parameter in
the WHAZAN Theory Manual, a roughness parameter of 0.07 (corresponding to flat land, few trees) was
chosen as equivalent to the surface roughness of 3 centimeters used to represent rural topography in modeling
to develop the distance tables for this guidance. A roughness parameter of 0.17 (for woods or rural area or
industrial site) was chosen as equivalent to  1 meter, which was used to develop the urban distance tables.
Data were added to the WHAZAN chemical database for acrylonitrile and allyl alcohol; ethylene oxide and
chlorine were already included in the database.

        For WHAZAN modeling of the gases ethylene oxide and chlorine and the liquid acrylonitrile, the
WHAZAN dense cloud dispersion model was used. For the alternative-case release of allyl alcohol, the
buoyant plume dispersion model was used for consistency with the guidance methodology. The release rates
estimated using the guidance methodology were entered as the release rates for all of the WHAZAN
modeling.

        The WHAZAN dense cloud dispersion requires a "volume dilution factor" as one of its inputs. This
factor was not explained; it was presumed to account for dilution of pressurized gases with air upon release.
For the gases modeled, the default dilution factor of 60 was used; for acrylonitrile, a dilution factor of 0 was
entered.  This factor appears to have little effect on the distance results.

        D.5   Worst-Case Consequence Analysis for Flammable Substances

        The equation used for the vapor cloud explosion analysis for the worst case involving flammable
substances is given in Appendix C. This equation is based on the TNT-equivalency method of the UK Health
and Safety Executive, as presented in the publication of the Center for Chemical Process Safety of the
American Institute of Chemical Engineers (AIChE), Guidelines for Evaluating the Characteristics of Vapor

April 15, 1999                                   D - 12

-------
                                                                                       Appendix D
	Technical Background

Cloud Explosions, Flash Fires, and BLEVEs (1994).  The assumption was made for the worst case that the
total quantity of the released substance is in the flammable part of the cloud.  The AIChE document lists this
assumption as one of a number that have been used for vapor cloud explosion blast prediction; it was chosen
as a conservative assumption for the worst-case analysis.  The yield factor of 10 percent was a conservative
worst-case assumption, based on information presented in the AIChE document. According to the AIChE
document, reported values for TNT equivalency for vapor cloud explosions range from a fraction of one
percent to tens of percent; for most major vapor cloud explosions, the range is one to ten percent.

        The endpoint for the vapor cloud explosion analysis, 1 psi, is reported to cause damage such as
shattering of glass windows and partial demolition of houses.  Skin laceration from flying glass also is
reported. This endpoint was chosen for the consequence analysis because of the potential for serious injuries
to people from the property damage that might result from an explosion.

        The TNT equivalent model was chosen as the basis for the consequence analysis because of its
simplicity and wide use. This model does not take into account site-specific factors and many chemical-
specific factors that may affect the results of a vapor cloud explosion. Other methods are available for vapor
cloud explosion modeling;  see the list of references in Appendix A for some publications that include
information on other vapor cloud explosion modeling methods.

        D.6    Alternative Scenario Analysis for Gases

        The equation for estimating release rate of a gas from a hole  in a tank is based on the equations for
gas discharge rate presented in the Handbook of Chemical Hazard Analysis Procedures by the Federal
Emergency Management Agency (FEMA), DOT,  and EPA, and equations in EPA's Workbook of Screening
Techniques for Assessing Impacts of Toxic Air Pollutants. The equation for an instantaneous discharge
under non-choked flow conditions is:
                        m  = CdAh
                                    \
                                                            (D-7)
where:
               m
               Cd
               Ah
               Y
               Po
               Pi
               Po
Discharge rate (kg/s)
Discharge coefficient
Opening area (m2)
Ratio of specific heats
Tank pressure (Pascals)
Ambient pressure (Pascals)
Density (kg/m3)
Under choked flow conditions (maximum flow rate), the equation becomes:
April 15, 1999
                                              D-13

-------
Appendix D
Technical Background

m urf Ah A

( 2 } —
2* y-l
v/7 Q i
'^U+iJ
(D-8)
        For development of the equation and gas factors presented in this guidance, density (p) was rewritten
as a function of pressure and molecular weight, based on the ideal gas law:
                                          P  =
                                 pQ MW
                                  R Tt
                                                     (D-9)
where:
MJF    =      Molecular weight (kilograms per kilomole)
R       =      Gas constant (8,314 Joules per degree-kilomole)
Tt      =      Tank temperature (K)
The choked flow equation can be rewritten:
                          m =
                                                            '"
                             MW
                             8314
                                                                          (D-10)
        To derive the equation presented in the guidance, all the chemical-specific properties, constants, and
appropriate conversion factors were combined into the "Gas Factor" (GF). The discharge coefficient was
assumed to have a value of 0.8, based on the screening value recommended in EPA's Workbook of Screening
Techniques for Assessing Impacts of Toxic Air Pollutants. The GF was derived as follows:
               GF =  132.2 x  6,895  x 6.4516xlO
                                                   ~4
°\
'(
2
Y + ly
YH
I7"
N
7WF
8314
                                                                          (D-ll)
where:
132.2
6,895
6.4516xlO-4
Conversion factor for Ibs/min to kg/s
Conversion factor for psi to Pascals (p0)
Conversion factor for square inches to square meters (Ah)
        GF values were calculated for all gases regulated under CAA section 112(r) and are listed in
Appendix B, Exhibit B-l, for toxic gases and Appendix C, Exhibit C-2, for flammable gases.
April 15, 1999
                                              D-14

-------
                                                                                       Appendix D
                                                                               Technical Background
        From the equation for choked flow above and the equation for the GF above, the initial release rate
for a gas from a hole in a tank can be written as:
                                  QR = HA x Pt  x — x  GF
(D-12)
where:         QR     =      Release rate (pounds per minute)
               HA     =      Hole area (square inches)
               Pt      =      Tank pressure (psia)
               Tt      =      Tank temperature (K)

        D.7    Alternative Scenario Analysis for Liquids

               D.7.1   Releases from Holes in Tanks

        The equation for estimating release rate of a liquid from a hole in a tank is based on the equations for
liquid release rate presented in the Handbook of Chemical Hazard Analysis Procedures by FEMA, DOT,
and EPA and EPA's Workbook of Screening Techniques for Assessing Impacts of Toxic Air Pollutants.
The equation for the instantaneous release rate is:
                                                                   - Pa
where:         m      =      Discharge rate (kilograms per second)
               Ah      =      Opening area (square meters)
               Cd      =      Discharge coefficient (unitless)
               g       =      Gravitational constant (9.8 meters per second squared)
               P!      =      Liquid density (kilograms per cubic meter)
               P0      =      Storage pressure (Pascals)
               Pa      =      Ambient pressure (Pascals)
               HL      =      Liquid height above bottom of container (meters)
               Hh      =      Height of opening (meters)

        A version of this equation is presented in the guidance for use with data found in Appendix B, for
gases liquefied under pressure. The equation in the text was derived using the conversion factors listed below
and density factors and equilibrium vapor pressure or tank pressure values listed in Appendix B, Exhibit B-l.
Equation D-13 becomes:
 QR =  132.2x6.4516xl(T4x0.8x,ffi4 ^16.018xrfx[2x9.8xl6.018xrfxZ^x0.0254+2P x6895]     (D-14)
April 15, 1999                                    D - 15

-------
Appendix D
Technical Background
where:         QR            =       Release rate (pounds per minute)
               HA            =       Hole area (square inches)
               132.2          =       Conversion factor for kilograms per second to pounds per minute
               6.4516 x 10"4   =       Conversion factor for square inches to square meters (HA)
               0.8            =       Discharge coefficient (0.8)
               d              =       Liquid density (pounds per cubic foot); can derived by using the
                                      density factor: l/(DFx0.033)
               16.018         =       Conversion factor for pounds per cubic feet to kilograms per cubic
                                      meters (D)
               9.8            =       Gravitational  constant (meters per second squared)
               LH            =       Height of liquid above hole (inches)
               2.54 x 10"2     =       Conversion factor for inches to meters (LH)
               Pg             =       Gauge pressure in tank (psi)
               6,895          =       Conversion factor for psi to Pascals (Pg)

After combining the conversion factors and incorporating the density factor (DF), this equation becomes:
                            QR  = HA x 6.82
                                               DF2           DF


For liquids stored at ambient pressure, Equation D-13 becomes:
07  - « *% « '.                   (D-15)
                                                     PL  ~ Hk)                           (»-!«)
        To derive the equation presented in the guidance for liquids under ambient pressure, all the chemical-
specific properties, constants, and conversion factors were combined into the "Liquid Leak Factor" (LLF).
The discharge coefficient was assumed to have a value of 0.8, based on the screening value recommended in
EPA's Workbook of Screening Techniques for Assessing Impacts of Toxic Air Pollutants. The LLF was
derived  as follows:
               LLF = 132.2 x  6.4516  x i(r4  x 0.1594 x  0.8  x ^/2 x  9.8  x p/       (D-17)
where:         LLF           =       Liquid Leak Factor (pounds per minute-inches2 5)
               132.2          =       Conversion factor for kilograms per second to pounds per minute
                                      (m)
               6.4516 x 10"4   =       Conversion factor for square inches to square meters (Ah)
               0.1594         =       Conversion factor for square root of inches to square root of meters
                                      (HL-Hh)
               0.8            =       Discharge coefficient (0.8)
               9.8            =       Gravitational constant (meters per second squared)
               P!             =       Liquid density (kilograms per cubic meter)
April 15, 1999                                    D-16

-------
                                                                                          Appendix D
                                                                                 Technical Background
        LLF values were calculated for all liquids regulated under CAA section 112(r) and are listed in
Appendix B, Exhibit B-2, for toxic liquids and Appendix C, Exhibit C-3, for flammable liquids.

        From the equation for liquid release rate from a hole in a tank at ambient pressure and the equation
for the LLF, the initial release rate for a liquid from a tank under atmospheric pressure can be written as:
                     QRL =  HA
                                                            LLF
                                                             (D-18)
where:
QRL
HA
LH
Liquid release rate (pounds per minute)
Hole area (square inches)
Height of liquid above hole (inches)
                D.7.2  Releases from Pipes

        The equation used to estimate releases of liquids from pipes is the Bernoulli equation. It assumes
that the density of the liquid is constant and does not account for losses in velocity due to wall friction. The
equation follows:
                            (Pa  ~
                                D
                                                                                            (D-19)
where:
P
                va
                vb
                D
Isolating Vb yields:
Pressure at pipe inlet (Pascals)
Pressure at pipe outlet (Pascals)
Height above datum plane at pipe inlet (meters)
Height above datum plane at pipe release (meters)
Gravitational acceleration (9.8 meters per second squared)
Newton's law proportionality factor (1.0)
Operational velocity (meters per second)
Release velocity (meters per second)
Density of liquid (kilograms per cubic meter)
          b ~  ^
                                        D
                      2g(Za- Zh)  + Fa2
                                                                                            (D-20)
        To develop the equation presented in the text, conversion factors for English units and constants
were incorporated as follows:
April 15, 1999
                                               D-17

-------
Appendix D
Technical Background
            2x6895x(P7,-14.7)xJDFx0.033
                         16.08
(2x9.8xQ.3048x(Za-Zfe) +  0.005082xFa2
                                          (D-21)
where:         Vb      =      Release velocity (feet per minute)
               197     =      Conversion factor for meters per second to feet per minute
               6895    =      Conversion factor for psi to Pascals
               PT      =      Total pipe pressure (psi)
               14.7    =      Atmospheric pressure (psi)
               16.08   =      Conversion factor for pounds per cubic foot to kilograms per cubic meter
               DF     =      Density factor (1/(0.033 DF)= density in pounds per cubic foot)
               9.8     =      Gravitational acceleration (meters per second2)
               0.3048  =      Conversion factor for feet to meters
               Za-Zb    =      Change in pipe elevation, inlet to outlet (feet)
               0.00508=      Conversion factor for feet per minute to meters per second
               Va      =      Operational velocity (feet per minute)

        D.8    Vapor Cloud Fires

        Factors for leaks from tanks for flammable substances (GF and LLF) were derived as described for
toxic substances (see above).

        The endpoint for estimating impact distances for vapor cloud fires of flammable substances is the
lower flammability limit (LFL).  The LFL is one of the endpoints for releases of flammable substances
specified in the RMP Rule. It was chosen to provide a reasonable, but not overly conservative, estimation of
the possible extent of a vapor cloud fire.

        D.9    Pool  Fires

        A factor used for estimating the distance to a heat radiation level from a pool fire that could cause
second degree burns from a 40-second exposure was developed based on equations presented in the AIChE
document, Guidelines for Evaluating the Characteristics of Vapor Cloud Explosions, Flash Fires, and
BLEVEs and in the Netherlands TNO document, Methods for the Determination of Possible Damage to
People and Objects Resulting from Releases of Hazardous Materials  (1992).  The AIChE and TNO
documents present a point-source model that assumes that a selected fraction of the heat of combustion is
emitted as radiation in  all directions. The radiation per unit area received by a target  at some distance from
the point source is given by:
                                                 471 x:
                                                                                         (D-22)
April 15, 1999
                                              D-18

-------
                                                                                        Appendix D
                                                                                Technical Background
where:         q       =      Radiation per unit area received by the receptor (Watts per square meter)
               m      =      Rate of combustion (kilograms per second)
               ua      =      Atmospheric transmissivity
               Hc      =      Heat of combustion (Joules per kilogram)
               /       =      Fraction of heat of combustion radiated
               x       =      Distance from point source to receptor (meters)

        The fraction of combustion energy dissipated as thermal radiation (f in the equation above) is
reported to range from 0.1 to 0.4. To develop factors for estimating distances for pool fires, this fraction was
assumed to be 0.4 for all the regulated flammable substances. The heat radiation level (q) was assumed to be
5 kilowatts (5,000 Watts) per square meter. This level is reported to cause second degree burns from a 40-
second exposure.  One of the endpoints for releases of flammable substances specified in the RMP Rule is 5
kilowatts per square meter for 40 seconds.  It was assumed that people would be able to escape from the heat
in 40 seconds. The atmospheric transmissivity (ua) was assumed equal to one.

        For  a pool fire of a flammable substance with a boiling point above the ambient temperature, the
combustion rate can be estimated by the following empirical equation:
                                             0.0010 H  A
                                    m =  	        c
                                                                                         (D-23)
                                              + Cp (Tb -  Ta}


where:         m      =      Rate of combustion (kilograms per second)
               Hc      =      Heat of combustion (Joules per kilogram)
               Hv      =      Heat of vaporization (Joules per kilogram)
               Cp      =      Liquid heat capacity (Joules per kilogram-degree K)
               A      =      Pool area (square meters)
               Tb      =      Boiling temperature (K)
               Ta      =      Ambient temperature (K)
               0.0010  =      Constant

        Combining Equations D-22 and D-23 (above), and assuming a heat radiation level of 5,000 Watts
per square meter, gives the following equation for liquid pools of substances with boiling points above
ambient temperature:
\
                                                    0.0010 A
                                                       471 
-------
Appendix D
Technical Background
                             x  =
                                      \
                                                 0.0001 A
                                        5,00071  (Hv +  C(Tb
                                                                                         (D-25)
where:         x       =      Distance from point source to receptor (meters)
               q       =      Radiation per unit area received by the receptor = 5,000 Watts per square
                              meter
               Hc      =      Heat of combustion (Joules per kilogram)
               /       =      Fraction of heat of combustion radiated = 0.4
               Hv      =      Heat of vaporization (Joules per kilogram)
               Cp      =      Liquid heat capacity (Joules per kilogram-degree Kelvin)
               A       =      Pool area (square meters)
               Tb      =      Boiling temperature (K)
               Ta      =      Ambient temperature (K)
               0.0010  =      Constant

        For a pool fire of a flammable substance with a boiling point below the ambient temperature (i.e.,
liquefied gases) the combustion rate can be estimated by the following equation, based on the TNO
document:
                                       m =
                                             0.0010 Hc A
                                                  If..
                                                                                         (D-26)
where:         m      =      Rate of combustion (kilograms per second)
               Hv     =      Heat of vaporization (Joules per kilogram)
               Hc     =      Heat of combustion (Joules per kilogram)
               A      =      Pool area (square meters)
               0.0010 =      Constant

Then the equation for distance at which the radiation received equals 5,000 Watts per square meter becomes:


                                                                                         (D-27)
                                     x =
                                              \
                                                  0.0001 A
                                                 5,00071 H
where:
               x      =      Distance from point source to receptor (meters)
               5,000  =      Radiation per unit area received by the receptor (Watts per square meter)
               Hc     =      Heat of combustion (Joules per kilogram)
               Hv     =      Heat of vaporization (Joules per kilogram)
               A      =      Pool area (square meters)
               0.0001 =      Derived constant (see equations D-20 and D-21)
April 15, 1999
                                              D-20

-------
                                                                                       Appendix D
	Technical Background

        A "Pool Fire Factor" (PFF) was calculated for each regulated flammable liquid and gas (to be applied
to gases liquefied by refrigeration) to allow estimation of the distance to the heat radiation level that would
lead to second degree burns. For the derivation of this factor, ambient temperature was assumed to be 298 K
(25 °C). Other factors are discussed above.  The PFF for liquids with boiling points above ambient
temperature was derived as follows:
                          PFF =
                                    c
                                      \
            0.0001
                                                (D-28)
5,00071 [Hv + C(Tb -  298)]
where:         5,000   =      Radiation per unit area received by the receptor (Watts per square meter)
               Hc      =      Heat of combustion (Joules per kilogram)
               Hv      =      Heat of vaporization (Joules per kilogram)
               Cp      =      Liquid heat capacity (Joules per kilogram-degree K)
               Tb      =      Boiling temperature (K)
               298     =      Assumed ambient temperature (K)
               0.0001  =      Derived constant (see above)

For liquids with boiling points below ambient temperature, the PFF is derived as follows:

                                    PFF = H
                                                \
            0.0001
                                                (D-29)
          5,00071 H
where:         5,000   =      Radiation per unit area received by the receptor (Watts per square meter)
               Hc      =      Heat of combustion (Joules per kilogram)
               Hv      =      Heat of vaporization (Joules per kilogram)
               0.0001  =      Derived constant (see above)

        Distances where exposed people could potentially suffer second degree burns can be estimated as the
PFF multiplied by the square root of the pool area (in square feet), as discussed in the text.

        D.10   BLEVEs

        Reference Table 30, the table of distances for BLEVEs, was developed based on equations presented
in the AIChE document, Guidelines for Evaluating the Characteristics of Vapor Cloud Explosions, Flash
Fires, and BLEVEs. The Hymes point-source model for a fireball, as cited in the AIChE document, uses the
following equation for the radiation received by a receptor:

                                          2.2 Ta R Hc  mf°'67
                                     q =  	a-	—                            (D-30)
where:         q       =      Radiation received by the receptor (Watts per square meter)
               mf      =      Mass of fuel in the fireball (kg)

April 15, 1999                                    D - 21

-------
Appendix D
Technical Background	

               ua      =      Atmospheric transmissivity
               Hc      =      Heat of combustion (Joules per kilogram)
               R      =      Radiative fraction of heat of combustion
               L      =      Distance from fireball center to receptor (meters)
               TI      =      3.14

Hymes (as cited by AIChE) suggests the following values for R:

        R      =      0.3 for vessels bursting below relief valve pressure
        R      =      0.4 for vessels bursting at or above relief valve pressure

For development of Reference Table 30, the following conservative assumptions were made:

        R      =      0.4


        The effects of radiant heat on an exposed person depend on both the intensity of the radiation and the
duration of the exposure.  For development of the table of distances for BLEVEs, it was assumed that the
time of exposure would equal the duration of the fireball. The AIChE document gives the following
equations for duration of a fireball:


                               tc =  0.45  mfv3 for mf < 30,000 kg                       (D-31)

and

                               tc =  2.6  mfv6 for mf > 30,000 kg                       (D-32)

where:         mf      =      Mass of fuel (kg)
               tc      =      Combustion duration (seconds)

        According to several sources (e.g., Eisenberg, et al.,  Vulnerability Model, A Simulation System for
Assessing Damage Resulting from Marine Spills; Mudan, Thermal Radiation Hazards from Hydrocarbon
Pool Fires (citing K. Buettner)), the effects of thermal radiation are generally proportional to radiation
intensity to the four-thirds power times time of exposure. Thus, a thermal "dose" can be estimated using the
following equation:


                                          Dose =  t q4'3                                  (D-33)

where:         t       =      Duration of exposure (seconds)
               q      =      Radiation intensity (Watts/m2)

        The thermal "dose" that could cause second-degree burns was estimated assuming 40 seconds as the
duration of exposure and 5,000 Watts/m2 as the radiation intensity. The corresponding dose is 3,420,000
(Watts/m2)4/3-second.

April 15, 1999                                    D - 22

-------
                                                                                       Appendix D
	Technical Background

        For estimating the distance from a fireball at which a receptor might receive enough thermal radiation
to cause second degree burns, the dose estimated above was substituted into the equation for radiation
received from a fireball:
                                               ,420,000
                                                  t
                                                                                         (D-34)
                               3,420,000
                                          3/4
                                    t
                                                2.2
                                         R Hc mf°'67
                                                                                         (D-35)
where:
L
               m
               R
               t
                                   L =
                                        \
2.2 Ta R Hc m°'67
471
3,420,000
t
3/4
                                                                                         (D-36)
Distance from fireball center to receptor (meters)
Radiation received by the receptor (Watts per square meter)
Mass of fuel in the fireball (kg)
Atmospheric transmissivity (assumed to be 1)
Heat of combustion (Joules per kilogram)
Radiative fraction of heat of combustion (assumed to be 0.4)
Duration of the fireball (seconds) (estimated from the equations above);
assumed to be duration of exposure
        Equation D-36 was used to develop the reference table for BLEVEs presented in the text (Reference
Table 30).

        D.ll   Alternative Scenario Analysis for Vapor Cloud Explosions

        According to T.A. Kletz, in "Unconfmed Vapor Cloud Explosions" (Eleventh Loss Prevention
Symposium, sponsored by AIChE, 1977), unconfmed vapor cloud explosions almost always result from the
release of flashing liquids. For this reason, the quantity in the cloud for the alternative scenario vapor cloud
explosion in this guidance is based on the fraction flashed from the release of a flammable gas liquefied under
pressure. The guidance provides a method to estimate the quantity in the cloud from the fraction flashed into
vapor plus the quantity that might be carried along as aerosol. The recommendation to use twice the quantity
flashed as the mass in the cloud (so long as it does not exceed the total amount of flammable substance
available) is based on the method recommended by the UK Health and Safety Executive (HSE),  as cited in the
AIChE document, Guidelines for Evaluating the Characteristics of Vapor Cloud Explosions,  Flash Fires,
and BLEVEs. The factor of two is intended to allow for spray and aerosol formation.
April 15, 1999
                                              D-23

-------
Appendix D
Technical Background

        The equation for the flash fraction, for possible use in for the alternative scenario analysis, is based
on the Netherlands TNO document, Methods for the Calculation of the Physical Effects of the Escape of
Dangerous Material (1980), Chapter 4, "Spray Release." The following equation is provided:


                                                         T C     T
where:         Xvapa   =      Weight fraction of vapor after expansion
               Xvap b   =      Weight fraction of vapor before expansion (assumed to be 0 for calculation
                              of the flash fraction)
               Tb      =      Boiling temperature of gas compressed to liquid (K)
               T,      =      Temperature of stored gas compressed to liquid (K)
               C,      =      Specific heat of gas compressed to liquid (Joules/kilogram-K)
               hv      =      Heat of evaporation of gas compressed to liquid (Joules/kilogram)

        To develop a Flash Fraction Factor (FFF) for use in consequence analysis, compressed gases were
assumed to be stored at 25 °C (298 K) (except in cases where the gas could not be liquefied at that
temperature). The equation for FFF is:

                                     777777   I   TbCi , 298
                                           =   ~~   ~                                 (D"38)
where:         Tb      =      Boiling temperature of gas compressed to liquid (K)
               C,      =      Specific heat of gas compressed to liquid (Joules/kilogram-K)
               hv      =      Heat of evaporation of gas compressed to liquid (Joules/kilogram)
               298    =      Temperature of stored gas compressed to liquid (K)

        The recommendation to use a yield factor of 0.03 for the alternative scenario analysis for vapor cloud
explosions also is based on the UK HSE method cited by AIChE. According to the AIChE document, this
recommendation is based on surveys showing than most major vapor cloud explosions have developed
between 1 percent and 3 percent of available energy.
April 15, 1999                                    D - 24

-------
                         APPENDIX E




      WORKSHEETS FOR OFFSITE CONSEQUENCE ANALYSIS




                 Using the Methods in this Guidance
April 15, 1999

-------
                             WORKSHEET 1
                 WORST-CASE ANALYSIS FOR TOXIC GAS
1. Select Scenario (defined by rule for worst case as release of largest quantity
over 10 minutes)
• Identify toxic gas
• Identify largest quantity in
largest vessel or pipeline
• Identify worst-case
meteorological conditions
Name:
CAS number:

Quantity (pounds}:

Atmospheric stability class: F
Wind speed: 1.5 m/s
Ambient temperature: 25 °C
Relative humidity: 50%
Guidance
Reference
Chapter 2
Section 3.1
2. Determine Release Rate
• Estimate release rate
Quantity/10 min, except
gases liquefied by
refrigeration in some cases
• Revise release rate to
account for passive mitigation
(enclosure)
Release rate dbs/min):
Will release always take place in enclosure?
(If yes, go to next step)
Can release cause failure of enclosure?
(If yes, use unmitigated release rate)
Factor to account for enclosure: 0.55
Mitisated release rate dbs/min):

Section 3.1.1
Section 3. 1.2
3. Determine Distance to the Endpoint Specified by Rule
• Identify endpoint
• Determine gas density
Consider conditions (e.g.,
liquefied under pressure)
• Determine site topography
Rural and urban defined by
rule
• Determine appropriate
reference table of distances
Use 10-minute tables
• Find distance on reference
table
Endpoint (mg/L):

Dense:
Neutrallv buovant:

Rural:
Urban:

Reference table used (number):

Release rate/endpoint (neutrallv buovant):
Distance to endpoint (mi):
Exhibit B-l
Exhibit B-l
Section 2.1
Chapter 4
Reference
Tables 1-12
Chapter 4
Reference
Tables 1-12
April 15, 1999
                                   E- 1

-------
                             WORKSHEET 2
                WORST-CASE ANALYSIS FOR TOXIC LIQUID
1. Select Scenario (defined by rule for worst case as release of largest quantity to
form an evaporating pool)
• Identify toxic liquid
• Identify concentration for
solutions or mixtures
• Identify largest quantity in
largest vessel or pipeline
• Identify worst-case
meteorological conditions
Name:
CAS number:
Concentration in solution or mixture fwt %):
•
Quantitv (pounds}:
Quantitv of regulated substance in mixture:
* •
Atmospheric stability class: F
Wind speed: 1.5 m/s
Ambient temperature: 25 °C
Relative humidity: 50%
Guidance
Reference
Chapter 2
Section 3. 2
Section 3. 2. 4
for mixtures
2. Determine Release Rate
• Determine temperature of
spilled liquid
Must be highest maximum
daily temperature or process
temperature, or boiling point
for gases liquefied by
refrigeration
• Determine appropriate
liquid factors for release rate
estimation
Temperature of liquid (°C):

LFA:
LFB:
DF:
TCP:

Section 3. 2
Section 3.1.3
Section 3. 2,
Exhibits B-2,
B-4
Section 3.3,
Exhibit B-3
for water
solutions
Estimate Maximum Pool Area
• Estimate maximum pool
area
Spilled liquid forms pool 1
cm deep
Maximum pool area (ft2):

Section 3. 2. 3
Equation 3-6
April 15, 1999
                                   E-2

-------
                                WORKSHEET 2 (continued)
       Estimate Pool Area for Spill into Diked Area
• Estimate diked area
Consider failure of dikes or
overflow of diked area
Diked area (ft2): 	
Is diked area smaller than maximum area?	
(If no, use maximum area to estimate release rate)
Diked volume (ft3): 	
Spilled volume (ft3): 	
Is spilled volume smaller than diked volume?	
(If no, estimate overflow)
Overflow volume (ft3): 	
Overflow area (ft2): 	
Section 3.2.3
• Choose pool area for release
rate estimation
Maximum area, diked area,
or sum of diked area and
overflow area
Pool area (ft2):
Section 3.2.3
       Estimate Release Rate from Pool
• Estimate release rate for
undiked pool (maximum pool
area)
Based on quantity spilled,
LFAorLFB, andDF
Release rate (Ibs/min):
Section 3.2.2
Section 3.2.4
(mixtures)
Equation 3-3
or 3-4
• Estimate release rate for
diked pool (use pool area
from previous section)
Based on pool area and LFA
orLFB
Release rate (Ibs/min):
Section 3.2.2
Section 3.2.4
(mixtures)
Equation 3-7
or 3-8
• Revise release rate for
release in building
Apply factor to release rate
Release rate if outside (Ibs/min) 	
(Use release rate for undiked or diked pool)
Factor to account for enclosure: 0.1
Revised release rate (Ibs/min): 	
Section 3.2.3
Equations 3-9,
3-10
• Revise release rate for
temperature
Apply appropriate TCP to
release rate
Revised release rate (Ibs/min):
Section 3.2.5
Equation 3-11
  Estimate duration of release
Release duration (min):
Section 3.2.2
Equation 3-5
  April 15, 1999
                                            E-:

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                            WORKSHEET 2 (continued)
3. Determine Distance to the Endpoint
• Identify endpoint
Specified by rule
• Determine vapor density
• Determine site topography
Rural and urban defined by
rule
• Determine appropriate
reference table of distances
Based on release duration,
vapor density, topography
• Find distance on reference
table
Endpoint (mg/L):

Dense:
Neutrally buovant:
~
Rural:
Urban:

Reference table used (number}:

Release rate/endpoint (neutrallv buovant):
Distance to endpoint (mi):

Exhibit B-2
Exhibit B-2
Section 2.1
Chapter 4
Reference
Tables 1-12
Chapter 4
Reference
Tables 1-12
April 15, 1999
                                        E-4

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                                     WORKSHEET 3
               WORST-CASE ANALYSIS FOR FLAMMABLE SUBSTANCE
 1.  Select Scenario (defined by rule for worst case as vapor cloud explosion of
    largest quantity)
                                               Guidance
                                               Reference
• Identify flammable
substance
• Identify largest quantity in
largest vessel or pipeline
Consider total quantity of
flammable substance,
including non-regulated
substances inflammable
mixtures
Name: 	
CAS number:
Chapter 2
Section 3.1
Quantity (pounds):
2.  Determine Distance to the Endpoint (endpoint specified by the rule as 1 psi overpressure;
    yield factor assumed to be 10% for TNT-equivalent model)
• Estimate distance to 1 psi
using Reference Table
Find quantity, read distance
from table
Distance to 1 psi (mi):
Chapter 5
Reference
Table 13
• Alternatively, estimate
distance to 1 psi using
equation
For pure substance:
   Heat of combustion (kJ/kg):  	
For mixture:
   Heat of combustion of major component
   (kJ/kg): 	
   Heats of combustion of other components
   (kJ/kg): 	, 	,  	

Distance to 1 psi (mi).  	
Chapter 5
Appendix C.I
Appendix C.2
Exhibit C-l
  April 15, 1999
                                           E-5

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                                     WORKSHEET 4
                ALTERNATIVE SCENARIO ANALYSIS FOR TOXIC GAS
1. Select Scenario
                                                Guidance
                                                Reference
  Identify toxic gas
• Identify conditions of
storage or processing of toxic
gas
Treat gases liquefied by
refrigeration as liquids
• Develop alternative
scenario
  >  More likely than worst
case
  >  Should reach endpoint
off site
• Identify average
meteorological conditions
Name: 	
CAS number:
Non-liquefied pressurized gas:
Gas liquefied under pressure:
In tank:  	
In pipeline: 	
Other (describe): 	
Chapter 6
Chapter 7
Section 7.1
Describe scenario:
Atmospheric stability class: D
Wind speed: 3.0 m/s
Ambient temperature: 25 °C
Relative humidity: 50%
2. Determine Release Rate
• Estimate gas release rate
from hole in tank (choked/
maximum flow) for
  >  Pressurized gas
  >  Gas liquefied under
pressure released from vapor
space
Hole area (in2):  	
Tank pressure (psia):
Tank temperature (K):
GF: 	
Release rate (Ibs/min):
Section 7.1.1
Equation 7-1
Exhibit B-l
• Estimate flashing liquid
release rate from hole in tank
  >  Gas liquefied under
pressure released from liquid
space
Hole area (in2):  	
Tank pressure (psig): 	
DF: 	
Liquid height above hole (in):
Release rate (Ibs/min): 	
Section 7.1.2
Equation 7-2
Exhibit B-l
  April 15, 1999
                                           E-6

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                            WORKSHEET 4 (continued)
• Estimate flashing liquid
release rate from break in
long pipeline
> Gas liquefied under
pressure completely filling
pipeline
• Estimate release duration
• Revise release rate for
passive mitigation (enclosure)
• Revise release rate for
active mitigation
• Estimate release duration
(mitigated release)
• Other release rate
estimation
Initial flow rate (Ibs/min):
DF:
Initial flow velocity (ft/min):
Pipe pressure (psi):
Change in pipe elevation (ft):
Cross-sectional pipe area (ft2):
Release rate (Ibs/min):
~
Time to stop release (min):
Time to emptv tank or pipe (min):
Default release duration: 60 min
Release rate if outside (Ibs/min):
Factor to account for enclosure: 0.55
Revised release rate (Ibs/min):
~
Active mitigation technique used:

Time to stop release using active technique
(min):
Fractional release rate reduction by active
technique:
Revised release rate (Ib/min):
~
Release duration (min):

Release rate (Ib/min):
Method of release rate estimation (describe):

Release duration (min):
~
Sections 7.1.1
and 7.2.1
Exhibit B-l
Section 7.1.1
Section 7. 1.2
Section 3. 1.2

Section 7. 1.2

3. Determine Distance to the Endpoint
• Identify endpoint
Specified by rule
• Determine gas density
Consider conditions (e.g.,
liquefied under pressure,
refrigeration)
• Determine site topography
Rural and urban defined by
rule
Endpoint (mg/L):

Dense:
Neutrallv buovant:

Rural:
Urban:

Exhibit B-l
Exhibit B-l
Section 2.1
April 15, 1999
                                        E-7

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                            WORKSHEET 4 (continued)
• Determine appropriate
reference table of distances
Based on release duration,
vapor density, and
topography
• Find distance on reference
table
Reference table used (number):

Release rate/endpoint (neutrallv buovant):
Distance to endpoint (mi):

Chapter 8
Reference
Tables 14-25
Chapter 8
Reference
Tables 14-25
April 15, 1999

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                             WORKSHEET 5
          ALTERNATIVE SCENARIO ANALYSIS FOR TOXIC LIQUID
1. Select Scenario
• Identify toxic liquid Include
gases liquefied by
refrigeration
• Identify concentration for
solutions or mixtures
• Identify conditions of
storage or processing of toxic
liquid
• Develop alternative
scenario
> More likely than worst
case
> Should reach endpoint
off site
• Identify meteorological
conditions
Name:
CAS number:
Concentration in solution or mixture (wt %):

Atmospheric tank:
Pressurized tank:
Pipeline:
Other (describe}:


Describe scenario:



Atmospheric stability class: F
Wind speed: 3.0 m/s
Ambient temperature: 25 °C
Relative humidity: 50%
Guidance
Reference
Chapter 6
Chapter 7
Section 7.2
2. Determine Release Rate
Determine Liquid Release Rate and Quantity Released into Pool
• Estimate liquid release rate
from hole in atmospheric tank
• Estimate liquid release rate
from break in long pipeline
• Estimate liquid release
duration
Hole area (in2}:
LLF:
Liquid height above hole (in}:
Liquid release rate dbs/min}:
±
Initial flow rate dbs/min}:
DF:
Initial flow velocitv (ft/min):
Pipe pressure (psi):
Change in pipe elevation (ft}:
Cross-sectional pipe area (ft2}:
Liquid release rate dbs/min}:

Time to stop release (min):
Time to emvtv tank to level of hole (min}:
Section 7. 2.1
Equation 7-4
Exhibit B-2
Section 7. 2.1
Equations 7-5
-7-7
Exhibit B-2
Section 7. 2.1
April 15, 1999
                                  E-9

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                             WORKSHEET 5 (continued)
• Revise liquid release
duration for active mitigation
• Estimate quantity of liquid
released into pool
Liquid release rate times
duration
Active mitigation technique (describe}:

Time to stop release (min):

Quantity of liquid released (Ibs):

Section 7.2.2
Sections 7. 2.1,
7.2.2, 7.2.3
Determine Pool Area and Evaporation Rate from Pool
• Determine temperature of
spilled liquid
• Determine appropriate
liquid factors for release rate
estimation
Temperature of liquid (°C):

LFA:
LFB:
DF:
TCP:

Section 7.2.3
Sections 7.2.3,
3.2, and
Exhibits B-2,
B-4
Section 3. 3
and Exhibit B-
3 for water
solutions
Estimate Maximum Pool Area
• Estimate maximum pool
area
Spilled liquid forms pool 1
cm deep
Maximum pool area (ft2):

Section 7.2.3,
3.2.3 Equation
3-6
Estimate Pool Area for Spill into Diked Area
• Estimate diked area
Consider possibility of failure
of dikes or overflow of diked
area
• Choose pool area for
evaporation rate estimation
Maximum area, diked area,
or sum of diked area and
overflow area
Diked area (ft2):
Is diked area smaller than maximum area?
(If no, use maximum area to estimate release rate)
Diked volume (ft3):
Spilled volume (ft3):
Is spilled volume smaller than diked volume?
(If no, estimate overflow)
Overflow volume (ft3):
Overflow area (ft2):

Pool area (ft2):

Section 7.2.3,
3.2.3
Section 7.2.3,
3.2.3
April 15, 1999
                                        E- 10

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                             WORKSHEET 5 (continued)
Estimate Release Rate from Pool
• Estimate release rate for
undiked pool
Based on quantity spilled,
LFAorLFB, andDF
• Estimate release rate for
diked pool (use pool area
from previous section)
Based on pool area and LFA
orLFB
• Revise release rate for
temperature
Apply appropriate TCP to
release rate
• Revise release rate for
release in building
Apply factor to release rate
• Revise release rate for
active mitigation technique
• Compare liquid release rate
and pool evaporation rate
• Choose smaller release rate
as release rate for analysis
Release rate (Ibs/min):

Release rate (Ibs/min):

Revised release rate (Ibs/min):

Release rate if outside (Ibs/min):
Factor to account for enclosure: 0.05
Revised release rate (Ibs/min):
~
Active mitigation technique used:

Fractional release rate reduction by active
technique:
Revised release rate (Ib/min):
'
Release rate (Ib/min) :

Section 7.2 3
Section 3. 2. 4
(mixtures)
Equation 7-8
or 7-9
Sections 7.2.3,
3.2.2
Section 3. 2. 4
(mixtures)
Equation 7- 10
or 7-11
Sections 7.2.3,
3.2.5
Equation 3-11
Sections 7.2.3,
3.2.3
Section 7.2.3
Section 7.2.3
3. Determine Distance to the Endpoint
• Identify endpoint
Specified by rule
• Determine vapor density
• Determine site topography
Rural and urban defined by
rule
Endpoint (mg/L):

Dense:
Neutrallv buovant:
~
Rural:
Urban:

Exhibit B-2
Exhibit B-2
Section 2.1
April 15, 1999
                                        E- 11

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                            WORKSHEET 5 (continued)
• Determine appropriate
reference table of distances
Based on release duration,
vapor density, and
topography
• Find distance on reference
table
Reference table used (number):

Release rate/endpoint (neutrallv buovant):
Distance to endpoint (mi):

Chapter 8
Reference
Tables 14-25
Chapter 8
Reference
Tables 14-25
April 15, 1999
                                        E- 12

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                           WORKSHEET 6
     ALTERNATIVE SCENARIO ANALYSIS FOR FLAMMABLE SUBSTANCE
1. Select Scenario
• Identify flammable
substance
• Identify conditions of
storage or processing of
flammable substance
Treat gases liquefied by
refrigeration as liquids
• Identify appropriate
scenario
> Vapor cloud fire
> Pool fire
> BLEVE/fireball
> Vapor cloud explosion
> Other (not covered by
OCA Guidance)
Name:
CAS number:

Non-liquefied pressurized gas:
Gas liquefied under pressure:
Gas liquefied bv refrigeration:
Liquid under atmospheric pressure:
Liquid underpressure greater than atmospheric :_
Other (describe):


Alternative scenario/type of fire or explosion
(describe):



Guidance
Reference
Chapter 6
2. Determine Release Rate
Determine Release Rate for Vapor Cloud Fire
• For gas releases and
flashing liquid releases, see
Worksheet 4
• For liquid releases (non-
flashing), see Worksheet 5
Release rate (Ibs/min):

Liquid release rate (Ibs/min):
Liquid release duration (min):
Ouantitv in pool (Ibs):
Release rate to air (Ibs/min):

Section 9.1
Section 7.1
Equations 7-1,
7-2, 7-3
Exhibit C-2
Section 9.2
Section 7.2
Equations 7-4-
7-12
Exhibit C-3
Determine Pool Area for Pool Fire
Estimate pool area: See
Worksheet 5
Ouantitv in pool (Ibs):
Pool area (ft2):

Sections 10.2
Section 7.2
Exhibits C-2,
C-3
April 15, 1999
                                E- 13

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                             WORKSHEET 6 (continued)
Determine Quantity for BLEVE
Determine quantity in tank
Ouantitv fibs):
'
Section 10.3
Determine Quantity for Vapor Cloud Explosion
Determine quantity in tank
Ouantitv fibs):
'
Section 10.4
3. Determine Distance to the Endpoint
• Identify endpoint suitable
for scenario
> LFL
> 5kW/m2for40
seconds
> 1 psi overpressure
Endpoint:

Chapter 6
Exhibits C-2,
C-3
Determine Distance to LFL for Vapor Cloud Fire
• Determine vapor density
• Determine site topography
Rural and urban defined by
rule
• Determine appropriate
reference table of distances
Based on vapor density and
topography
• Find distance on reference
table
Dense:
Neutrallv buovant:
~
Rural:
Urban:

Reference table used (number):

Release rate/endpoint (neutrallv buovant):
Distance to LFL (mi):

Exhibit B-2
Section 2.1
Section 10.1
Reference
Tables 26-29
Section 10.1
Reference
Tables 26-29
Determine Distance to Heat Radiation Endpoint for Pool Fire
• Calculate distance to 5
kW/m2
PFF:
Pool area (ft2):
Distance (ft):
Section 10.2
Equation 10-1
April 15, 1999
                                        E- 14

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                             WORKSHEET 6 (continued)
Determine Distance to Heat Radiation Endpointfor BLEVE
Determine distance for
radiation from fireball
equivalent to 5 kW/m2 for 40
seconds
Quantitv (Ibs):
Distance (mi):

Section 10.3
Reference
Table 30
Determine Distance to Overpressure Endpoint For Vapor Cloud Explosion
Determine distance to 1 psi
Quantity in cloud can be
less than total quantity
Yield factor can be less
than 10%
FFF:
Quantitv flashed:
Yieldfactor:
Distance to 1 psi (mi):

Section 10.4
Exhibit C-2
Reference
Table 13
April 15, 1999
                                        E- 15

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                APPENDIX F




CHEMICAL ACCIDENT PREVENTION PROVISIONS




    As codified at 40 CFR part 68 as of July 1, 1998

-------
Pt. 67, App. A
                                                       40 CFR Ch.  I (7-1-98 Edition)
local  agent, any  noncompliance  pen-
alties owed by the source owner or op-
erator shall be  paid  to the  State  or
local agent.

  APPENDIX A TO PART 67—TECHNICAL
          SUPPORT DOCUMENT

  NOTE: 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]

 APPENDIX B TO PART  67— INSTRUCTION
                MANUAL
  NOTE: 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]

  APPENDIX C TO PART 67—COMPUTER
                PROGRAM
  NOTE: 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  param-
    eters.
68.25  Worst-case release scenario analysis.
68.28  Alternative release scenario analysis.
68.30  Defining offsite impacts—population.
68.33  Defining  offsite  impacts—environ-
    ment.
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.
                                            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 permitting
                                               authority or designated agency require-
                                               ments.
                                            68.220  Audits.
                                            APPENDIX A  TO PART 68—TABLE  OF Toxic
                                               ENDPOINTS
                                              AUTHORITY:  42  U.S.C.  7412(r),  7601 (a) (1),
                                            7661-7661f.
                                              SOURCE: 59 FR 4493, Jan. 31,  1994,  unless
                                            otherwise noted.
                                          36

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Environmental Protection Agency
                                §68.2
        Subpart A—General

§68.1  Scope.
  This part sets forth the list of regu-
lated substances  and  thresholds,  the
petition process for adding or deleting
substances to the  list of regulated sub-
stances, the requirements for owners or
operators  of  stationary  sources  con-
cerning  the prevention of  accidental
releases, and  the  State accidental re-
lease  prevention   programs  approved
under  section  112(r). The list  of sub-
stances, threshold quantities, and acci-
dent  prevention  regulations promul-
gated under this part  do  not limit in
any  way  the general  duty  provisions
under section 112(r)(l).

§68.2  Stayed provisions.
  (a) Notwithstanding any other provi-
sion 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 "sta-
tionary  source,"  to the  extent  that
such definition includes naturally oc-
curring   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 requires
an owner or operator to treat as a regu-
lated flammable substance:
  (i) Gasoline,  when in distribution or
related storage for use as fuel for inter-
nal combustion engines;
  (ii) Naturally occurring  hydrocarbon
mixtures  prior to  entry into a petro-
leum refining process unit or a natural
gas processing plant. Naturally  occur-
ring 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   and
that do not have  a National Fire Pro-
tection Association  flammability haz-
ard rating of 4, the definition of which
is in the NFPA 704, Standard System
for the Identification of the Fire  Haz-
ards of Materials, National  Fire  Pro-
tection Association, Quincy, MA,  1990,
available from the  National Fire  Pro-
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  de-
scribed in paragraph (a) of this section:
  Condensate means hydrocarbon liquid
separated from natural gas that  con-
denses because  of changes in tempera-
ture,  pressure,  or both, and  remains
liquid at standard conditions.
  Crude oil means any naturally occur-
ring, 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  means
any processing  site engaged in the ex-
traction  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, com-
pressor, or similar equipment shall not
be considered a "processing site"  un-
less  such equipment  is physically lo-
cated within  a  natural  gas  processing
plant (gas plant) site.
  Petroleum  refining process unit means
a process unit used in  an establishment
primarily engaged in  petroleum refin-
ing as defined in the Standard Indus-
trial Classification  code for petroleum
refining (2911) and used  for the follow-
ing:   Producing transportation  fuels
(such as  gasoline, diesel fuels, and jet
fuels), heating fuels (such as kerosene,
fuel gas distillate, and fuel oils), or lu-
bricants; separating petroleum; or sep-
arating, cracking, reacting,  or reform-
ing  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 re-
forming, catalytic cracking, crude dis-
tillation, lube oil processing, hydrogen
production,  isomerization, polymeriza-
tion, thermal processes, and blending,
sweetening, and treating processes. Pe-
troleum refining process units include
sulfur plants.
  Produced  water   means  water   ex-
tracted from the earth from an oil or
natural gas production well, or that is
                                      37

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§68.3
          40 CFR Ch. I  (7-1-98 Edition)
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 unantici-
pated  emission  of  a  regulated sub-
stance 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  adminis-
trator of the U.S. Environmental Pro-
tection Agency.
  AIChE/CCPS means the American In-
stitute  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 de-
sign 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 or
otherwise result in exposure to a regu-
lated substance  under  normal  condi-
tions of processing and use.
  ASME  means  the  American Society
of Mechanical Engineers.
  CAS means the Chemical  Abstracts
Service.
  Catastrophic release  means a  major
uncontrolled emission,  fire,  or  explo-
sion, involving one  or  more regulated
substances that presents imminent and
substantial  endangerment  to  public
health and the environment.
  Classified information  means "classi-
fied  information"  as  defined  in  the
Classified Information Procedures Act,
18 U.S.C. App.  3,  section l(a) as "any
information or material that has been
determined by  the United States Gov-
ernment   pursuant  to  an  executive
order, statute, or regulation, to require
protection against unauthorized disclo-
sure for  reasons of national security."
  Condensate means hydrocarbon liquid
separated from natural gas  that con-
denses due to changes  in temperature,
pressure, or both, and remains liquid at
standard conditions.
  Covered process means a process that
has a  regulated substance present  in
more than a threshold quantity as  de-
termined under §68.115.
  Crude oil means any naturally occur-
ring, 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 De-
partment of Transportation.
  Environmental receptor means natural
areas  such as national or state parks,
forests, or monuments; officially  des-
ignated wildlife sanctuaries, preserves,
refuges, or  areas; and  Federal wilder-
ness areas,  that could  be exposed  at
any time to toxic concentrations, radi-
ant 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 elec-
tric or gas welding, cutting, brazing, or
similar flame or spark-producing oper-
ations.
  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 human
that results either  from  direct expo-
sure to toxic concentrations;  radiant
heat; or overpressures from accidental
releases  or  from  the   direct  con-
sequences 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 a
new process, process equipment, or reg-
ulated substance, an alteration of proc-
ess chemistry  that  results  in  any
change  to  safe  operating limits,   or
                                      38

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Environmental Protection Agency
                                §68.3
other alteration that introduces a new
hazard.
  Mechanical integrity means the proc-
ess of ensuring that process equipment
is fabricated from the proper materials
of  construction  and  is properly  in-
stalled,  maintained, and replaced  to
prevent  failures  and   accidental  re-
leases.
  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,   or
equipment designed or deployed to cap-
ture 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 energy
input.  Active mitigation means equip-
ment,  devices,  or  technologies that
need human, mechanical, or other en-
ergy input to function.
  NFPA means the National Fire Pro-
tection Association.
  Natural gas processing plant (gas plant)
means any processing site  engaged in
the extraction of  natural  gas liquids
from field gas, fractionation of mixed
natural gas liquids to natural gas prod-
ucts, or both, classified as North Amer-
ican Industrial Classification  System
(NAICS) code 211112 (previously Stand-
ard Industrial Classification (SIC) code
1321).
  Offsite means areas beyond the prop-
erty boundary of the stationary source,
and areas within  the property bound-
ary 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 establishment
primarily engaged in  petroleum  refin-
ing as  defined in NAICS code 32411 for
petroleum refining (formerly SIC code
2911) and used for the following: Pro-
ducing  transportation  fuels  (such  as
gasoline,  diesel fuels,  and  jet fuels),
heating  fuels (such as  kerosene, fuel
gas distillate,  and fuel  oils), or lubri-
cants;  Separating petroleum; or Sepa-
rating,  cracking,  reacting, or  reform-
ing  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 re-
forming, catalytic cracking, crude dis-
tillation,  lube  oil  processing, hydrogen
production, isomerization, polymeriza-
tion, thermal processes,  and blending,
sweetening, and treating processes. Pe-
troleum 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  sub-
stances, or combination of these activi-
ties. For  the purposes  of this defini-
tion,  any  group  of vessels  that  are
interconnected,  or  separate  vessels
that are located such that a  regulated
substance could be involved in a poten-
tial release, shall be considered a sin-
gle process.
  Produced  water means  water   ex-
tracted 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 em-
ployees or contractors at the station-
ary source.
  Public receptor  means  offsite   resi-
dences, institutions (e.g., schools,  hos-
pitals), industrial, commercial, and of-
fice  buildings, parks,  or recreational
areas inhabited or occupied by the  pub-
lic at any time without restriction by
the stationary source where members
of the  public could be exposed to toxic
concentrations, radiant heat,  or  over-
pressure,  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 replace-
ment that  satisfies  the design speci-
fications.
  RMP means the  risk management
plan required under subpart  G of this
part.
                                      39

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§68.10
          40 CFR Ch. I (7-1-98 Edition)
  SIC means Standard Industrial Clas-
sification.
  Stationary source  means any build-
ings,  structures,  equipment,  installa-
tions, or substance emitting stationary
activities which belong to the same in-
dustrial  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 accidental
release  may occur.  The  term station-
ary source does not apply to transpor-
tation,  including storage  incident  to
transportation, of any  regulated  sub-
stance or any  other extremely hazard-
ous substance under the provisions of
this part. A stationary source includes
transportation  containers   used   for
storage not  incident to transportation
and  transportation   containers  con-
nected to  equipment at a  stationary
source for loading or unloading. Trans-
portation 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. A
stationary source does not include nat-
urally  occurring  hydrocarbon  res-
ervoirs. Properties shall  not be consid-
ered contiguous  solely  because of  a
railroad or pipeline right-of-way.
  Threshold quantity means the quan-
tity  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 line
failure that results in the greatest dis-
tance  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]
§68.10  Applicability.
  (a) An owner or operator of a station-
ary  source  that  has  more than  a
threshold quantity of a regulated sub-
stance  in a  process,  as  determined
under §68.115,  shall comply with  the re-
quirements 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  require-
ments. 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 has
not had an accidental release of  a regu-
lated substance where  exposure to the
substance, its reaction products, over-
pressure generated by an explosion in-
volving the substance, or radiant  heat
generated  by  a fire  involving the sub-
stance led to  any of the following off-
site:
  (i) Death;
  (ii) Injury; or
  (iii)  Response  or restoration  activi-
ties for an  exposure  of an  environ-
mental receptor;
  (2) The  distance to a toxic or flam-
mable 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  sta-
tionary source  and  local emergency
planning and response organizations.
  (c)  Program  2  eligibility  require-
ments.  A  covered process is subject to
Program 2 requirements  if it does not
meet the eligibility requirements of ei-
ther paragraph  (b) or paragraph (d) of
this section.
  (d)  Program  3  eligibility  require-
ments.  A  covered process is subject to
Program 3 if the process does not meet
the  requirements of paragraph (b) of
this section, and if either of the  follow-
ing conditions is met:
                                      40

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Environmental Protection Agency
                               §68.12
  (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 criteria
of its Program level, the owner or oper-
ator  shall  comply  with  the  require-
ments 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  owner
or operator of a stationary source sub-
ject 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 addi-
tion  to  meeting  the  requirements of
paragraph (a) of this section, the  owner
or operator of a stationary source with
a process eligible for Program 1, as pro-
vided 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 distance
to a  toxic or flammable  endpoint de-
fined 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 nearest
public receptor: [list process(es)]. With-
in 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
CFR  68.10(b)(l)). No additional meas-
ures  are  necessary to prevent offsite
impacts  from  accidental releases.  In
the event of fire, explosion, or a release
of a regulated substance from the proc-
ess(es), entry  within the distance  to
the specified endpoints may pose a dan-
ger to public  emergency  responders.
Therefore, public emergency respond-
ers should not enter this area except as
arranged  with the emergency  contact
indicated in the RMP. The undersigned
certifies that, to the best of my knowl-
edge,   information,  and belief, formed
after  reasonable inquiry, the informa-
tion submitted is  true, accurate, and
complete.   [Signature,   title,   date
signed]."
  (c) Program 2 requirements.  In addi-
tion  to  meeting the requirements  of
paragraph (a) of this section, the owner
or operator of a stationary source with
a process subject to Program 2, as pro-
vided in§68.10(c), shall:
  (1) Develop and implement  a manage-
ment  system as provided in §68.15;
  (2)  Conduct a hazard assessment  as
provided in  §§68.20 through 68.42;
  (3) Implement the Program 2 preven-
tion steps provided in §§68.48  through
68.60 or implement the Program 3 pre-
vention   steps   provided   in   §§68.65
through 68.87;
  (4) Develop and implement an emer-
gency 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 addi-
tion  to  meeting the requirements  of
paragraph (a) of this section, the owner
or operator of a stationary source with
a process subject to Program 3, as pro-
vided in§68.10(d) shall:
  (1) Develop and implement  a manage-
ment  system as provided in §68.15;
  (2)  Conduct a hazard assessment  as
provided in  §§68.20 through 68.42;
  (3)  Implement  the  prevention  re-
quirements  of §§68.65 through 68.87;
  (4) Develop and implement an emer-
gency 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
                                      41

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§68.15
          40 CFR Ch. I  (7-1-98 Edition)
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 sta-
tionary source with processes subject
to Program  2 or Program 3 shall de-
velop a management system to oversee
the  implementation of the risk man-
agement program elements.
  (b) The owner  or operator shall as-
sign a qualified person  or position that
has  the overall  responsibility for  the
development, implementation,  and in-
tegration of the  risk management pro-
gram elements.
  (c)  When  responsibility for  imple-
menting  individual requirements  of
this part is  assigned to persons other
than the person  identified under para-
graph  (b) of this  section, the names or
positions of these people shall be docu-
mented and  the  lines of authority de-
fined through an organization chart or
similar document.
[61 FR 31718, June 20, 1996]

  Subpart B—Hazard Assessment

 SOURCE: 61  FR 31718, June 20, 1996, unless
otherwise noted.

§68.20  Applicability.
  The  owner or  operator  of a station-
ary  source  subject to  this part shall
prepare  a  worst-case release  scenario
analysis as provided in §68.25 of this
part and complete  the  five-year acci-
dent 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 pro-
vided in appendix A of this part.
  (2)  Flammables.  The endpoints  for
flammables vary according to the sce-
narios studied:
  (i) Explosion.   An overpressure  of 1
psi.
  (ii) Radiant heat/exposure time. A ra-
diant heat of 5 kw/m2 for 40 seconds.
  (iii)  Lower  flammability  limit.  A
lower flammability limit as provided in
NFPA documents  or other  generally
recognized sources.
  (b) Wind speed/atmospheric stability
class. For the worst-case release analy-
sis, 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  demonstrate
that local meteorological data applica-
ble to the  stationary source  show a
higher minimum wind speed or less sta-
ble atmosphere  at all times during the
previous three years, these minimums
may  be  used.  For  analysis  of alter-
native 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  for
the site, based  on temperature/humid-
ity data  gathered  at the stationary
source or at a local meteorological sta-
tion;  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 at
the stationary source or at a local me-
teorological 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 toxic
substance, release height may be deter-
mined 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  ensure
that tables or models used for disper-
sion analysis of regulated toxic sub-
stances appropriately account  for gas
density.
                                      42

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Environmental Protection Agency
                               §68.25
  (g)  Temperature  of  released  sub-
stance.  For  worst case, liquids  other
than  gases  liquified  by  refrigeration
only shall be considered to be released
at the  highest daily maximum tem-
perature, based  on data  for  the pre-
vious three  years  appropriate for  the
stationary source, or at process tem-
perature, whichever  is higher. For al-
ternative scenarios, substances may be
considered to be released at a process
or ambient temperature that  is appro-
priate for the scenario.

§68.25  Worst-case   release   scenario
    analysis.
  (a) The owner or operator shall ana-
lyze 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 greatest
distance in  any direction to an end-
point provided  in  appendix A of this
part resulting from  an accidental re-
lease  of  regulated  toxic  substances
from  covered  processes under  worst-
case conditions defined in §68.22;
  (ii)  One  worst-case release  scenario
that is estimated to create the greatest
distance in  any direction to an end-
point defined in §68.22(a) resulting from
an accidental release of regulated flam-
mable substances  from covered  proc-
esses  under  worst-case  conditions  de-
fined in §68.22;  and
  (iii)  Additional  worst-case  release
scenarios for a hazard class if a worst-
case release from another covered proc-
ess at the stationary source potentially
affects public receptors different from
those potentially affected by the worst-
case 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  quan-
tity shall be the greater of the follow-
ing:
  (1) For substances  in a vessel,  the
greatest amount held in a single vessel,
taking  into  account  administrative
controls that limit the maximum quan-
tity; or
  (2) For substances in pipes, the great-
est amount  in a pipe, taking into ac-
count   administrative  controls  that
limit the maximum quantity.
  (c)  Worst-case  release  scenario—toxic
gases.  (1)  For regulated  toxic  sub-
stances that are normally gases at am-
bient temperature and handled as a gas
or as a liquid under pressure, the owner
or  operator  shall  assume  that  the
quantity in the vessel or pipe, as deter-
mined  under paragraph  (b) of this sec-
tion, is released  as a gas over 10  min-
utes. 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  not
contained  by passive mitigation sys-
tems or if the contained  pool would
have a depth of 1 cm or  less, the owner
or operator shall assume that the sub-
stance is  released  as  a  gas  in 10  min-
utes;
  (ii) If the released substance  is con-
tained 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 instantaneously
to form a liquid pool.  The volatiliza-
tion rate  (release  rate) shall be cal-
culated at the boiling point of the sub-
stance and at the  conditions  specified
in paragraph (d) of this section.
  (d)  Worst-case  release  scenario—toxic
liquids.  (1)  For  regulated toxic  sub-
stances that are normally  liquids  at
ambient temperature, the owner or op-
erator  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  the
liquid spreads to 1  centimeter deep un-
less passive  mitigation  systems are in
place that  serve to  contain  the  spill
and  limit the surface area. Where pas-
sive 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
                                      43

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§68.28
          40 CFR Ch. I  (7-1-98 Edition)
account the actual surface characteris-
tics.
  (2) The volatilization rate shall ac-
count for the highest daily maximum
temperature  occurring  in   the  past
three years,  the temperature  of  the
substance in  the vessel, and the  con-
centration of the substance if the  liq-
uid spilled is a mixture or solution.
  (3) The rate of release to air shall be
determined from the volatilization rate
of the liquid pool. The owner or opera-
tor may use  the methodology  in  the
RMP  Offsite  Consequence  Analysis
Guidance or any other  publicly avail-
able techniques  that  account for  the
modeling conditions and are recognized
by  industry as  applicable as part of
current practices.  Proprietary models
that account for the  modeling  condi-
tions may be used provided the owner
or  operator  allows the implementing
agency  access to  the model and  de-
scribes model features and differences
from publicly available models to local
emergency planners upon request.
  (e)   Worst-case  release   scenario—
flammables. The owner or operator shall
assume that the  quantity of the  sub-
stance, as determined under paragraph
(b)  of this section, vaporizes resulting
in a vapor cloud  explosion. A yield fac-
tor of  10  percent of  the available en-
ergy 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 distance
to the  endpoints. The owner or  opera-
tor may  use the  methodology provided
in the RMP  Offsite Consequence Analy-
sis  Guidance  or  any  commercially or
publicly available air dispersion model-
ing techniques, provided the techniques
account  for the  modeling  conditions
and are recognized by industry  as ap-
plicable  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
considered for  the analysis of worst
case provided that the mitigation sys-
tem is capable of withstanding the re-
lease event triggering the scenario and
would still function as intended.
  (h) Factors in selecting a worst-case sce-
nario. Notwithstanding  the provisions
of paragraph  (b)  of  this section, the
owner or operator shall select  as the
worst  case for  flammable  regulated
substances or the worst  case for regu-
lated toxic substances, a scenario based
on the following factors  if such a sce-
nario would result in a greater distance
to an endpoint  defined in §68.22(a) be-
yond the stationary source boundary
than the scenario provided under para-
graph (b) of this section:
  (1)  Smaller  quantities  handled  at
higher  process  temperature or pres-
sure; 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 release
scenario for each regulated toxic sub-
stance held in a covered process(es) and
at  least one  alternative release  sce-
nario to represent all flammable  sub-
stances 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 off-
site, 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 fail-
ures 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
                                      44

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Environmental Protection Agency
                               §68.39
  (v)  Shipping container  mishandling
and breakage or  puncturing leading to
a spill.
  (c)  Parameters to  be applied.  The
owner or operator shall use the appro-
priate 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 Guidance
or any commercially or publicly avail-
able  air   dispersion  modeling  tech-
niques,  provided  the  techniques  ac-
count for the specified modeling condi-
tions  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.  Ac-
tive  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—popu-
   lation.
  (a) The owner or operator shall esti-
mate  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. Popu-
lation shall  include residential popu-
lation.  The  presence  of   institutions
(schools, hospitals, prisons), parks  and
recreational  areas, and major commer-
cial,  office,  and  industrial  buildings
shall be noted in the RMP.
  (c) Data sources acceptable. The owner
or operator  may use  the  most recent
Census data, or other updated informa-
tion, to estimate the population poten-
tially affected.
  (d) Level of accuracy. Population shall
be estimated to two significant digits.

§ 68.33  Defining offsite impacts—envi-
    ronment.
  (a) The owner or operator shall list in
the   RMP   environmental   receptors
within a circle with its  center at  the
point of the release and a radius deter-
mined by the distance to the endpoint
defined in §68.22(a)  of this part.
  (b)  Data  sources  acceptable.  The
owner or operator may rely on infor-
mation provided on local U.S. Geologi-
cal 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 re-
view  and  update  the  offsite   con-
sequence analyses  at  least once every
five years.
  (b) If changes in processes, quantities
stored or handled,  or  any other aspect
of the stationary source  might reason-
ably  be expected  to  increase or  de-
crease the distance to the endpoint by
a factor of two or more, the owner or
operator shall  complete a revised anal-
ysis 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  de-
scription of the vessel or pipeline  and
substance selected  as worst case,  as-
sumptions and parameters used,   and
the  rationale  for   selection;  assump-
tions shall include use of any adminis-
trative  controls and any passive miti-
gation that were assumed to limit  the
quantity that  could be released. Docu-
mentation  shall  include  the  antici-
pated effect of the controls and mitiga-
tion on the release  quantity and rate.
  (b)  For alternative release scenarios,
a description  of the  scenarios identi-
fied, assumptions and parameters used,
and the  rationale  for the selection of
specific  scenarios;  assumptions  shall
include use of  any administrative  con-
trols and any mitigation that were as-
sumed to limit the quantity that could
                                      45

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§68.42
          40 CFR Ch. I  (7-1-98 Edition)
be released.  Documentation shall in-
clude the  effect  of  the controls and
mitigation on the release quantity and
rate.
  (c)   Documentation   of  estimated
quantity released, release rate, and du-
ration of release.
  (d)  Methodology used to determine
distance to endpoints.
  (e) Data used to estimate population
and  environmental  receptors  poten-
tially affected.

§68.42  Five-year accident history.
  (a) The owner or operator shall in-
clude in the  five-year accident history
all  accidental  releases from  covered
processes that resulted in  deaths,  inju-
ries, or significant property damage on
site, or known offsite deaths, injuries,
evacuations,  sheltering  in  place, prop-
erty damage,  or  environmental dam-
age.
  (b) Data required. For each accidental
release included, the  owner or operator
shall report the following  information:
  (1) Date, time, and approximate dura-
tion 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 esti-
mates may be provided to  two signifi-
cant digits.

 Sub pa it C—Program 2  Prevention
              Program

  SOURCE: 61 FR 31721, June 20, 1996, unless
otherwise noted.

§68.48  Safety information.
  (a) The owner or operator shall com-
pile and maintain the following up-to-
date safety information related to the
regulated  substances,  processes,  and
equipment:
  (1) Material Safety Data Sheets  that
meet  the  requirements  of  29   CFR
1910.1200(g);
  (2) Maximum intended  inventory  of
equipment in which the regulated sub-
stances are stored or processed;
  (3) Safe upper  and  lower tempera-
tures,  pressures,  flows,  and composi-
tions;
  (4) Equipment specifications; and
  (5) Codes and standards used to de-
sign, build, and operate the process.
  (b) The owner or operator shall en-
sure that the  process is designed  in
compliance with  recognized and  gen-
erally  accepted good engineering prac-
tices. Compliance with Federal or state
regulations that address industry-spe-
cific safe design or with industry-spe-
cific design codes and standards may be
used to  demonstrate  compliance with
this paragraph.
  (c) The owner or operator shall up-
date the safety information if a major
change occurs that makes the informa-
tion inaccurate.

§68.50  Hazard review.
  (a) The owner or operator shall  con-
duct a review of the hazards associated
with the regulated substances, process,
and procedures. The review  shall iden-
tify the following:
  (1) The hazards associated with the
process and regulated substances;
  (2) Opportunities for equipment mal-
functions or human errors  that could
cause an accidental release;
  (3) The safeguards used or needed  to
control the hazards or prevent equip-
ment malfunction or human error; and
  (4) Any steps used or needed to detect
or monitor releases.
  (b) The  owner or operator may use
checklists developed by persons or or-
ganizations knowledgeable  about the
process and  equipment as a guide  to
conducting the review.  For processes
designed to meet industry standards or
Federal or state design rules, the  haz-
ard  review  shall,  by inspecting  all
equipment,  determine  whether  the
process is designed, fabricated,  and op-
erated in accordance with the applica-
ble standards or rules.
                                      46

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Environmental Protection Agency
                               §68.56
  (c) The owner or operator shall docu-
ment the results of the review and en-
sure that problems identified are re-
solved in a timely manner.
  (d)  The review shall be  updated at
least once every five years. The owner
or operator shall also conduct reviews
whenever  a major change in the proc-
ess 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 pre-
pare written operating procedures that
provide clear  instructions or steps for
safely conducting activities associated
with  each covered process consistent
with  the  safety information for that
process.  Operating  procedures  or in-
structions provided by equipment man-
ufacturers  or  developed by persons or
organizations  knowledgeable about the
process and equipment  may be used as
a basis for a stationary source's operat-
ing procedures.
  (b) The  procedures shall  address the
following:
  (1) Initial  startup;
  (2) Normal operations;
  (3) Temporary operations;
  (4)  Emergency shutdown  and oper-
ations;
  (5) Normal shutdown;
  (6)  Startup  following  a  normal  or
emergency shutdown or a major change
that requires a hazard review;
  (7)  Consequences  of  deviations  and
steps required to correct or avoid devi-
ations; and
  (8) Equipment inspections.
  (c) The  owner or  operator  shall en-
sure that the  operating procedures are
updated,  if  necessary,  whenever  a
major change  occurs and prior to start-
up of the changed process.

§68.54  Training.
  (a)  The  owner or  operator  shall en-
sure that  each employee presently op-
erating 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-
edge, skills,  and  abilities  to  safely
carry out  the duties  and responsibil-
ities as provided in the operating pro-
cedures.
  (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 consultation
with the employees operating the proc-
ess,  shall  determine  the  appropriate
frequency of refresher training.
  (c) The owner  or operator may use
training conducted under  Federal or
state regulations  or  under industry-
specific standards or codes or training
conducted  by  covered process  equip-
ment vendors to  demonstrate compli-
ance with  this  section to the extent
that the training meets the  require-
ments of this section.
  (d) The owner  or operator shall en-
sure 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 pre-
pare  and  implement  procedures  to
maintain the  on-going mechanical in-
tegrity  of  the process  equipment.  The
owner or operator may use procedures
or  instructions  provided  by  covered
process equipment  vendors  or  proce-
dures in Federal or state regulations or
industry codes as  the basis for station-
ary 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 the
procedures applicable to the  employ-
ee'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.
                                     47

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§68.58
          40 CFR Ch. I  (7-1-98 Edition)
  (d) The owner  or  operator shall per-
form or  cause to be performed inspec-
tions  and tests on process equipment.
Inspection and testing procedures shall
follow recognized and generally accept-
ed good engineering practices. The fre-
quency of inspections and tests of proc-
ess equipment shall be consistent with
applicable     manufacturers'     rec-
ommendations, industry standards  or
codes,  good engineering practices, and
prior operating experience.

§68.58 Compliance  audits.
  (a) The owner  or  operator shall cer-
tify that they have  evaluated compli-
ance with the provisions of this  sub-
part at least  every  three years to ver-
ify 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 de-
velop 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  does
not apply to  any compliance  audit re-
port that is more than five years old.

§68.60 Incident  investigation.
  (a) The owner or operator shall inves-
tigate 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  shall
promptly address and resolve the inves-
tigation  findings   and  recommenda-
tions.  Resolutions  and corrective ac-
tions 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

  SOURCE: 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 opera-
tor shall  complete a  compilation of
written process safety  information be-
fore conducting  any  process   hazard
analysis required by the rule. The com-
pilation  of written process safety infor-
mation is to  enable the owner or opera-
tor and the employees involved  in oper-
ating the process to identify and under-
stand the hazards posed by those proc-
esses involving  regulated substances.
This process safety information shall
include information pertaining to the
hazards  of  the  regulated  substances
used or produced by the process, infor-
mation pertaining to the technology of
the process,  and information pertain-
ing 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.

  NOTE  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 contain
the information  required by this  subpara-
graph.
  (c)  Information   pertaining  to  the
technology of the process.
                                      48

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Environmental Protection Agency
                               §68.67
  (1) Information concerning the tech-
nology 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 in-
formation no longer exists, such infor-
mation may be  developed  in  conjunc-
tion with the process hazard analysis
in sufficient detail to support the anal-
ysis.
  (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 em-
ployed;
  (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 docu-
ment 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 document
that the equipment is designed, main-
tained, inspected, tested, and operating
in a safe manner.

§68.67  Process hazard analysis.
  (a) The  owner  or operator shall per-
form an initial process hazard analysis
(hazard evaluation) on  processes cov-
ered by this part. The  process  hazard
analysis  shall be  appropriate to  the
complexity  of the  process and shall
identify, evaluate, and control the haz-
ards involved in the process. The owner
or operator shall determine and docu-
ment the  priority order for conducting
process hazard analyses based on a ra-
tionale which  includes  such consider-
ations as extent of the process hazards,
number of potentially affected employ-
ees,  age of  the process, and operating
history of the process. The process haz-
ard analysis shall be conducted as soon
as possible,  but not later than June 21,
1999.  Process  hazards   analyses  com-
pleted  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 use
one  or more  of the  following meth-
odologies that  are appropriate to deter-
mine 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 meth-
odology.
  (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 and
their interrelationships  such as appro-
priate application  of detection meth-
odologies to provide early warning  of
releases. (Acceptable  detection meth-
ods  might include process  monitoring
and   control  instrumentation  with
alarms, and detection hardware such as
hydrocarbon sensors.);
  (4)  Consequences  of failure of engi-
neering 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
                                      49

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§68.69
          40 CFR Ch. I  (7-1-98 Edition)
evaluated. Also, one member of the
team must be  knowledgeable in the
specific process hazard analysis meth-
odology being used.
  (e) The owner or operator shall estab-
lish  a system to promptly address the
team's findings and recommendations;
assure that the  recommendations are
resolved in a  timely manner and that
the  resolution  is  documented; docu-
ment what actions  are  to be taken;
complete  actions as soon  as  possible;
develop a written  schedule  of when
these actions are to be completed; com-
municate   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 hazard
analysis shall be updated and revali-
dated by  a team meeting the require-
ments  in  paragraph (d) of this section,
to assure  that the process hazard anal-
ysis  is consistent  with  the  current
process. Updated and revalidated proc-
ess hazard analyses  completed to com-
ply with 29 CFR 1910.119(e) are accept-
able to meet  the requirements of this
paragraph.
  (g) The owner or operator shall  re-
tain process hazards analyses and up-
dates or revalidations for each process
covered by this section, as well as the
documented resolution of recommenda-
tions described in paragraph (e) of this
section for the life of the process.

§68.69   Operating procedures.
  (a) The owner or operator shall de-
velop and implement written operating
procedures that provide clear instruc-
tions for  safely  conducting activities
involved in each covered  process con-
sistent  with the process  safety infor-
mation 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 emergency
shutdown is required, and the assign-
ment  of  shutdown  responsibility   to
qualified  operators  to   ensure  that
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  pre-
sented by, the chemicals used  in the
process;
  (ii)  Precautions necessary to prevent
exposure,  including  engineering  con-
trols, administrative controls, and per-
sonal protective equipment;
  (iii) Control measures to be taken if
physical contact or airborne  exposure
occurs;
  (iv) Quality control for raw  materials
and control of hazardous chemical in-
ventory levels; and,
  (v) Any special or unique hazards.
  (4)  Safety  systems  and their func-
tions.
  (b)  Operating  procedures  shall be
readily accessible  to  employees  who
work in or maintain a process.
  (c) The operating procedures shall be
reviewed as  often as  necessary to as-
sure that they reflect current operat-
ing practice,  including changes that re-
sult from changes in process chemicals,
technology,   and   equipment,   and
changes  to  stationary  sources.  The
owner or operator shall certify annu-
ally that  these  operating procedures
are current and accurate.
  (d)  The owner  or operator shall de-
velop and  implement safe work prac-
tices  to provide for the control of haz-
ards during operations such as lockout/
tagout; confined space  entry; opening
process equipment or piping;  and  con-
trol over entrance  into a stationary
source  by  maintenance, contractor,
laboratory, or other support  personnel.
These safe work practices shall apply
to  employees and  contractor employ-
ees.

§68.71  Training.
  (a) Initial training. (1) Each  employee
presently involved in operating a proc-
ess, and each employee before being in-
volved in operating a newly assigned
process, shall be trained in an overview
                                      50

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Environmental Protection Agency
                               §68.73
of the process and in the operating pro-
cedures  as  specified  in  §68.69.  The
training shall include emphasis on the
specific  safety  and  health  hazards,
emergency  operations  including  shut-
down, and safe work practices applica-
ble to the employee's job tasks.
  (2) In  lieu of initial training for those
employees already involved in operat-
ing a process on June 21,  1999 an owner
or operator may certify in writing that
the employee has the  required knowl-
edge, skills,  and  abilities   to  safely
carry out the duties and responsibil-
ities as specified in the operating pro-
cedures.
  (b) Refresher training.  Refresher train-
ing shall be  provided  at least  every
three years,  and more often  if nec-
essary,  to each employee involved in
operating a process to  assure that the
employee understands  and adheres to
the current operating procedures of the
process. The owner or operator, in con-
sultation with the employees involved
in operating the  process, shall deter-
mine the appropriate frequency of re-
fresher  training.
  (c) Training documentation. The owner
or operator shall ascertain that  each
employee involved in operating a proc-
ess 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, and
the means used to verify that the  em-
ployee 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 de-
vices;
  (4) Emergency shutdown systems;
  (5) Controls  (including  monitoring
devices  and sensors, alarms, and inter-
locks) and,
  (6) Pumps.
  (b) Written procedures. The owner or
operator shall establish and implement
written procedures to maintain the on-
going integrity of process equipment.
  (c)  Training for process  maintenance
activities. The owner or operator shall
train each employee involved in main-
taining the on-going integrity of proc-
ess equipment in an overview of that
process and its hazards and in the pro-
cedures  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) Inspec-
tions 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 and
tests of process equipment shall be con-
sistent with applicable  manufacturers'
recommendations and good engineering
practices, and more frequently if deter-
mined to be necessary by prior operat-
ing experience.
  (4) The owner or operator shall docu-
ment each inspection  and test that has
been performed on process  equipment.
The documentation shall identify  the
date of the inspection  or test, the name
of the person who performed  the  in-
spection or test, the  serial number or
other  identifier  of the equipment  on
which the inspection  or test was per-
formed, 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 acceptable
limits (defined by the  process safety  in-
formation 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 con-
struction of new plants  and  equipment,
the owner or operator shall assure that
equipment  as  it is fabricated  is suit-
able  for  the  process application   for
which they will be used.
  (2)  Appropriate  checks and inspec-
tions 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  as-
sure that maintenance materials, spare
parts  and equipment  are suitable  for
the process application  for which they
will be used.
                                      51

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§68.75
          40 CFR Ch. I (7-1-98 Edition)
§ 68.75  Management of change.
  (a) The owner or operator shall estab-
lish and implement written procedures
to manage changes  (except for  "re-
placements in kind") to process chemi-
cals, technology,  equipment,  and proce-
dures;  and,   changes  to  stationary
sources that affect a covered  process.
  (b) The  procedures shall assure that
the following  considerations  are  ad-
dressed prior to any change:
  (1) The  technical  basis for the  pro-
posed change;
  (2) Impact  of change  on safety and
health;
  (3) Modifications to operating proce-
dures;
  (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 contract
employees whose job tasks will be af-
fected 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 para-
graph results in a change in the  process
safety information required by §68.65 of
this part,  such  information shall be up-
dated accordingly.
  (e) If a  change  covered by this para-
graph results in a change in the  operat-
ing 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 per-
form  a pre-startup  safety review  for
new  stationary sources  and for modi-
fied stationary sources when the modi-
fication is significant enough   to  re-
quire a change  in the process safety in-
formation.
  (b)  The pre-startup safety  review
shall  confirm that prior  to  the intro-
duction 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, a
process hazard analysis has been per-
formed and   recommendations  have
been  resolved  or implemented  before
startup;   and    modified  stationary
sources  meet  the requirements con-
tained  in  management  of  change,
§68.75.
  (4)  Training  of  each  employee  in-
volved in operating a process has been
completed.

§68.79 Compliance audits.
  (a) The owner  or operator shall cer-
tify that they  have evaluated compli-
ance with the provisions of this section
at least  every  three years to  verify
that the procedures  and practices  de-
veloped  under  the standard  are ade-
quate 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 inves-
tigate each incident which resulted in,
or could  reasonably have resulted in a
catastrophic release of a regulated sub-
stance.
  (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 persons
with appropriate knowledge and experi-
ence  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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Environmental Protection Agency
                               §68.87
  (5)  Any  recommendations  resulting
from the investigation.
  (e) The owner or operator shall estab-
lish a system to promptly  address and
resolve the incident report findings and
recommendations. Resolutions and cor-
rective actions shall be documented.
  (f) The report shall be reviewed with
all  affected personnel whose job tasks
are relevant to the  incident findings in-
cluding contract employees where  ap-
plicable.
  (g)  Incident  investigation   reports
shall be retained for five years.

§ 68.83  Employee participation.
  (a)  The owner or operator shall  de-
velop a written plan of action regard-
ing the implementation  of the  em-
ployee participation required by  this
section.
  (b) The owner or operator shall con-
sult with  employees  and their  rep-
resentatives on the conduct and devel-
opment of process hazards analyses and
on the  development of the other ele-
ments of process safety management in
this rule.
  (c) The owner or operator shall pro-
vide to employees and their representa-
tives  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 issue
a hot work permit for hot work oper-
ations conducted on or near a covered
process.
  (b)  The permit shall document that
the fire prevention and protection  re-
quirements in 29 CFR 1910.252(a) have
been  implemented  prior to beginning
the hot work operations; it shall indi-
cate  the date(s)   authorized  for  hot
work; and identify  the object on which
hot work is to be performed. The per-
mit shall be kept on file until comple-
tion of the hot work operations.

§ 68.87  Contractors.
  (a)  Application. This section  applies
to contractors performing maintenance
or repair,  turnaround,  major renova-
tion,  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
and drink services, laundry, delivery or
other supply services.
  (b)  Owner or  operator responsibilities.
(1) The owner or operator, when select-
ing  a contractor,  shall obtain  and
evaluate  information   regarding  the
contract  owner or  operator's  safety
performance and programs.
  (2) The owner or operator shall in-
form 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 ex-
plain to the contract owner or operator
the applicable provisions of subpart E
of this part.
  (4) The owner or operator shall de-
velop and  implement safe work  prac-
tices consistent with §68.69(d),  to  con-
trol the entrance, presence, and exit of
the  contract  owner or  operator  and
contract employees in covered  process
areas.
  (5) The owner or operator shall peri-
odically  evaluate the performance  of
the contract owner or operator in ful-
filling their obligations  as specified  in
paragraph (c) of this section.
  (c) Contract owner or operator respon-
sibilities.  (1) The contract owner or op-
erator shall assure that  each contract
employee is trained in the work prac-
tices  necessary  to safely perform his/
her job.
  (2) The contract  owner or operator
shall  assure that  each  contract  em-
ployee is instructed  in the known po-
tential 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 operator
shall document  that each contract em-
ployee has received and understood the
training  required  by this section. The
contract owner  or operator shall  pre-
pare a record  which contains the iden-
tity of the contract employee, the  date
of training, and  the means used to ver-
ify that  the employee  understood the
training.
  (4) The contract  owner or operator
shall  assure that  each  contract  em-
ployee 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
                                      53

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§68.90
          40 CFR Ch. I (7-1-98 Edition)
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

  SOURCE: 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 opera-
tor of a stationary source with Pro-
gram 2 and Program 3 processes  shall
comply with the requirements of §68.95.
  (b) The owner or operator of station-
ary source  whose employees will not
respond to accidental releases of  regu-
lated 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 coordinated
response actions with the local fire de-
partment; 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 de-
velop and implement an emergency re-
sponse program for the purpose of pro-
tecting public  health and the  environ-
ment.  Such program shall  include the
following elements:
  (1)  An   emergency   response  plan,
which shall be maintained  at  the sta-
tionary source  and contain  at least the
following elements:
  (i) Procedures for informing the pub-
lic and local emergency response agen-
cies about accidental releases;
  (ii)  Documentation of proper first-aid
and emergency medical treatment nec-
essary to treat accidental human expo-
sures; and
  (iii)  Procedures  and  measures  for
emergency response after an accidental
release of a regulated substance;
  (2) Procedures  for  the use of emer-
gency response equipment  and for its
inspection, testing, and maintenance;
  (3) Training for all employees in rel-
evant procedures; and
  (4) Procedures  to review and update,
as appropriate, the  emergency response
plan to  reflect changes at the station-
ary source and ensure that employees
are informed of changes.
  (b) A written plan that complies with
other Federal contingency plan regula-
tions or  is  consistent  with  the  ap-
proach   in  the   National   Response
Team's  Integrated  Contingency  Plan
Guidance  ("One  Plan")  and   that,
among other matters, includes the ele-
ments 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 de-
veloped  under paragraph (a)(l)  of this
section  shall be  coordinated with the
community  emergency  response  plan
developed under  42 U.S.C.  11003. Upon
request  of the local emergency plan-
ning committee or  emergency response
officials, the owner  or  operator  shall
promptly provide to the local  emer-
gency  response  officials  information
necessary  for  developing  and imple-
menting the  community emergency re-
sponse plan.

Subpart F—Regulated Substances
for Accidental  Release Prevention

  SOURCE: 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 amend-
ed,  identifies  their  threshold  quan-
tities, and establishes the requirements
for petitioning to  add  or  delete sub-
stances from the  list.

§68.115   Threshold  determination.
  (a) A  threshold quantity  of a regu-
lated substance  listed   in  §68.130  is
                                      54

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Environmental Protection Agency
                              §68.115
present at a  stationary  source if the
total quantity  of the regulated sub-
stance contained  in a process  exceeds
the threshold.
  (b)  For the purposes of determining
whether  more than a threshold quan-
tity 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 concentra-
tion of the regulated  substance in the
mixture  is one percent or greater by
weight, but the owner or operator can
demonstrate  that the partial pressure
of the regulated substance in the mix-
ture (solution) under handling  or stor-
age  conditions  in any portion of the
process is  less than  lO  millimeters  of
mercury (mm Hg), the amount of the
substance  in  the  mixture in  that por-
tion of the process need not be consid-
ered when determining whether  more
than a threshold quantity is present  at
the stationary source. The owner or op-
erator shall document this partial pres-
sure measurement or estimate.
  (2) Concentrations of a regulated flam-
mable substance in a mixture,  (i) General
provision. If  a regulated substance  is
present  in a mixture  and  the con-
centration 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 stationary
source. Except as provided  in para-
graph (b)(2) (ii) and (iii) of this section,
if the concentration of the substance is
one percent or greater by weight of the
mixture, then,  for purposes  of deter-
mining whether a  threshold quantity is
present at the stationary source, the
entire weight of the mixture shall  be
treated as  the regulated  substance un-
less  the  owner or operator  can  dem-
onstrate that the mixture itself does
not  have a  National Fire Protection
Association  flammability hazard  rat-
ing of 4. The demonstration shall be in
accordance with the definition of flam-
mability hazard rating 4 in  the NFPA
704,  Standard  System  for the Identi-
fication 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  and
flash point  shall be defined  and deter-
mined  in accordance with  NFPA 30,
Flammable   and  Combustible  Liquids
Code, National Fire  Protection Asso-
ciation,  Quincy,  MA,  1996.  Available
from the National Fire Protection  As-
sociation, 1 Batterymarch Park, Quin-
cy, MA  02269-9101. This  incorporation
by reference was  approved by  the  Di-
rector of the Federal  Register in  ac-
cordance 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-
08,  Waterside Mall,  401 M.  St. SW.,
Washington DC; or at the Office of Fed-
eral  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 in
gasoline, when in  distribution or relat-
ed storage for use as fuel for internal
combustion engines,  need not be  con-
sidered  when  determining   whether
more  than   a threshold  quantity  is
present at a stationary source.
  (iii)  Naturally occurring hydrocarbon
mixtures. Prior to  entry into a  natural
gas processing plant or a petroleum re-
fining  process  unit,  regulated  sub-
stances in naturally occurring hydro-
carbon mixtures need not be considered
when determining whether more than a
                                      55

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§68.120
          40 CFR Ch. I  (7-1-98 Edition)
threshold quantity is present at a sta-
tionary  source.   Naturally occurring
hydrocarbon  mixtures  include  any
combination of the following:  conden-
sate, crude  oil, field  gas, and produced
water, each as defined in §68.3 of this
part.
  (3) Articles. Regulated substances con-
tained in articles need not be consid-
ered 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 jani-
torial maintenance;
  (iii) Use by employees of foods, drugs,
cosmetics, or other personal items con-
taining the regulated substance; and
  (iv)  Use   of   regulated   substances
present in process water or non-contact
cooling water as drawn from the envi-
ronment 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 regu-
lated substance is manufactured, proc-
essed,  or used in a laboratory at a sta-
tionary source under the supervision of
a technically qualified individual as de-
fined in §720.3(ee) of this  chapter,  the
quantity of the substance need not be
considered  in determining  whether  a
threshold quantity is present.  This ex-
emption does not apply to:
  (i) Specialty chemical production;
  (ii)  Manufacture,  processing,  or  use
of substances in pilot plant  scale oper-
ations; 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 Ad-
ministrator to modify,  by  addition or
deletion,  the  list  of regulated  sub-
stances identified in §68.130. Based on
the information presented by the peti-
tioner, the Administrator may grant or
deny a petition.
  (b) A substance may be added to the
list if, in the case of  an  accidental re-
lease,  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 sub-
stance are available to determine that
the substance, in the case of an acci-
dental release, is not known  to cause
and may not be reasonably anticipated
to cause  death,  injury, or serious ad-
verse 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 under
title VI of the Clean Air Act, as amend-
ed, shall be added to the list.
  (e) The burden  of proof  is on the peti-
tioner to demonstrate that the criteria
for addition and deletion  are met. A pe-
tition will be denied if this demonstra-
tion is not made.
  (f) The Administrator will not accept
additional petitions on the same sub-
stance following publication  of  a final
notice of the decision to  grant or deny
a  petition,  unless new  data  becomes
available that could  significantly af-
fect the basis for the decision.
  (g)  Petitions  to modify the  list of
regulated substances must contain the
following:
  (1) Name  and   address  of  the peti-
tioner and a  brief description of the or-
ganization^) that the petitioner rep-
resents, if applicable;
  (2)  Name,   address, and  telephone
number of a  contact person for the pe-
tition;
  (3) Common chemical name(s), com-
mon synonym(s),  Chemical  Abstracts
Service number,  and chemical formula
and structure;
  (4) Action  requested (add or delete a
substance);
  (5) Rationale supporting the petition-
er's  position;  that is,  how  the  sub-
stance 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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Environmental Protection Agency
                              §68.130
  (6) Supporting data; that is, the peti-
tion must include sufficient  informa-
tion to scientifically support the re-
quest to modify the list. Such informa-
tion shall include:
  (i) A list of all support documents;
  (ii)  Documentation  of   literature
searches conducted, including, but not
limited to,  identification of the data-
base^)  searched,  the search  strategy,
dates covered, and printed results;
  (iii) Effects data (animal, human, and
environmental  test  data)  indicating
the potential for death,  injury, or seri-
ous 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 acci-
dent  history  data,  indicating the po-
tential  for  serious  adverse  human
health  or environmental  effects from
an accidental release. These data may
include, but are not limited  to, phys-
ical and chemical properties of the sub-
stance,  such as vapor pressure;  model-
ing results,  including data and assump-
tions used and model documentation;
and  historical  accident  data,  citing
data sources.
  (h)  Within 18 months  of receipt of a
petition,  the Administrator shall pub-
lish  in the FEDERAL REGISTER 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 held
by farmers, is exempt from all provi-
sions 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 listed
in Tables  1,  2, 3, and 4. Threshold quan-
tities 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.
TABLE 1 TO  §68.130.—LIST OF  REGULATED
  Toxic  SUBSTANCES  AND THRESHOLD QUAN-
  TITIES FOR ACCIDENTAL RELEASE PREVENTION
        [Alphabetical Order—77 Substances]
Chemical name
Acrolein [2-
Propenal].
Acrylonitrile [2-
Propenenitrile].
Acrylyl chloride [2-
Propenoyl chlo-
ride].
Allyl alcohol [2-
Propen-l-ol].
Allylamine [2-
Propen-l-amine].
Ammonia (anhy-
drous).
Ammonia (cone
20% or greater).
Arsenous tri-
chloride.
Arsine 	
Boron trichloride
[Borane,
trichloro-].
Boron trifluoride
[Borane,
trifluoro-].
Boron trifluoride
compound with
methyl ether
(1:1) [Boron,
trifluoro [oxybis
[metane]]-, T-4-.
Bromine 	
Carbon disulfide ..
Chlorine 	
Chlorine dioxide
[Chlorine oxide
(CI02)].
Chloroform [Meth-
ane, trichloro-].
Chloromethyl
ether [Methane,
oxybis[chloro-].
Chloromethyl
methyl ether
[Methane,
chloromethoxy-].
Crotonaldehyde
[2-Butenal].
Crotonaldehyde,
(E)- [2-Butenal,
(E)-].
Cyanogen chlo-
ride.
Cyclohexylamine
[Cyclohexanam-
ine].
Diborane
Dimethyldichloros-
ilane [Silane,
dichlorodimeth-
yl-].
1,1-
Dimethylhydraz-
ine [Hydrazine,
1,1-dimethyl-].
CAS No.
1 07-02-8

107-13-1

814-68-6


107-18-61

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
1 0049-04-4


67-66-3

542-88-1


1 07-30-2



41 70-30-3

1 23-73-9


506-77-4

108-91-8


1 9287-45-7
75-78-5



57-14-7



Threshold
quantity
(Ibs)
5,000

20,000

5,000


15,000

10,000

10,000

20,000

15,000

1,000
5,000


5,000


15,000





10,000
20,000
2,500
1,000


20,000

1,000


5,000



20,000

20,000


10,000

15,000


2,500
5,000



15,000



Basis for
listing
b

b

b


b

b

a, b

a, b

b

b
b


b


b





a, b
b
a, b
c


b

b


b



b

b


c

b


b
b



b



                                      57

-------
§68.130
           40 CFR Ch. I (7-1-98 Edition)
TABLE  1  TO  §68.130.—LIST OF  REGULATED
  Toxic SUBSTANCES AND THRESHOLD QUAN-
  TITIES FOR  ACCIDENTAL RELEASE PREVEN-
  TION—Continued
        [Alphabetical Order—77 Substances]
TABLE  1  TO  §68.130.—LIST OF  REGULATED
  Toxic SUBSTANCES AND THRESHOLD QUAN-
  TITIES FOR  ACCIDENTAL RELEASE PREVEN-
  TION—Continued
        [Alphabetical Order—77 Substances]
Chemical name
Epichlorohydrin
[Oxirane,
(chloromethyl)-].
Ethylenediamine
[1,2-
Ethanediamine].
Ethyleneimine
[Aziridine].
Ethylene oxide
[Oxirane].
Fluorine
Formaldehyde
(solution).
Furan
Hydrazine
Hydrochloric acid
(cone 37% or
greater).
Hydrocyanic acid
Hydrogen chloride
(anhydrous)
[Hydrochloric
acid].
Hydrogen fluoride/
Hydrofluoric
acid (cone 50%
or greater)
[Hydrofluoric
acid].
Hydrogen sele-
nide.
Hydrogen sulfide
Iron,
pentacarbonyl-
[Iron carbonyl
(Fe(CO)S), (TB-
5-11)-].
Isobutyronitrile
[Propanenitrile,
2-methyl-].
Isopropyl
chloroformate
[Carbonochlori-
dic acid, 1-
methylethyl
ester].
Methacrylonitrile
[2-
Propenenitrile,
2-methyl-].
Methyl chloride
[Methane,
chloro-].
Methyl
chloroformate
[Carbonochlori-
dic acid,
methylester].
Methyl hydrazine
[Hydrazine,
methyl-].
Methyl isocyanate
[Methane,
isocyanato-].
CAS No.
106-89-8


107-15-3


151-56-4

75-21-8

7782-41-4
50-00-0

1 1 0-00-9
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



74-87-3


79-22-1




60-34-4


624-83-9


Threshold
quantity
(Ibs)
20,000


20,000


10,000

10,000

1,000
15,000

5,000
15,000
15,000


2,500
5,000



1,000





500

10,000
2,500




20,000


15,000





10,000



10,000


5,000




15,000


10,000


Basis for
listing
b


b


b

a, b

b
b

b
b
d


a, b
a



a, b





b

a, b
b




b


b





b



a


b




b


a, b


Chemical name
Methyl mercaptan
[Methanethiol].
Methyl
thiocyanate
[Thiocyanic
acid, methyl
ester].
Methyltrichlorosil-
ane [Silane,
trichloromethyl-].
Nickel carbonyl ....
Nitric acid (cone
80% or greater).
Nitric oxide [Nitro-
gen oxide (NO)].
Oleum (Fuming
Sulfuric acid)
[Sulfuric acid,
mixture with
sulfur trioxide] 1.
Peracetic acid
[Ethaneperoxoic
acid].
Perchloromethyl-
mercaptan
[Methanesulfen-
yl chloride,
trichloro-].
Phosgene [Car-
bonic dichloride].
Phosphine 	
Phosphorus
oxychloride
[Phosphoryl
chloride].
Phosphorus tri-
chloride [Phos-
phorous tri-
chloride].
Piperidine
Propionitrile
[Propanenitrile].
Propyl
chloroformate
[Carbonochlori-
dic acid,
propylester].
Propyleneimine
[Aziridine, 2-
methyl-].
Propylene oxide
[Oxirane, meth-
yl-].
Sulfur dioxide (an-
hydrous).
Sulfur tetrafluoride
[Sulfur fluoride
(SF4), (T-4)-].
Sulfur trioxide 	
Tetramethyllead
[Plumbane,
tetramethyl-].
Tetranitromethane
[Methane,
tetranitro-].
CAS No.
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



1 1 0-89-4
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


Threshold
quantity
(Ibs)
10,000

20,000




5,000


1,000
15,000

10,000

10,000




10,000


10,000




500

5,000
5,000



15,000



15,000
10,000

15,000




10,000


10,000


5,000

2,500


10,000
10,000


10,000


Basis for
listing
b

b




b


b
b

b

e




b


b




a, b

b
b



b



b
b

b




b


b


a, b

b


a, b
b


b


                                         58

-------
Environmental Protection Agency
                                    §68.130
TABLE 1  TO  §68.130.—LIST  OF  REGULATED
  Toxic  SUBSTANCES AND THRESHOLD QUAN-
  TITIES  FOR  ACCIDENTAL  RELEASE  PREVEN-
  TION—Continued
         [Alphabetical Order—77 Substances]
TABLE 1  TO  §68.130.—LIST  OF  REGULATED
  Toxic  SUBSTANCES AND THRESHOLD QUAN-
  TITIES  FOR  ACCIDENTAL  RELEASE  PREVEN-
  TION—Continued
         [Alphabetical Order—77 Substances]
Chemical name
Titanium tetra-
chloride [Tita-
nium chloride
(TiCI4) (T-4)-].
Toluene 2,4-
diisocyanate
[Benzene, 2,4-
diisocyanato-1-
methyl-] 1 .
Toluene 2,6-
diisocyanate
[Benzene, 1,3-
diisocyanato-2-
methyl-] 1 .
Toluene
diisocyanate
(unspecified
isomer) [Ben-
zene, 1,3-
diisocyanatome-
thyl-]1.
CAS No.
7550-45-0



584-84-9




91-08-7




26471-62-5






Threshold
quantity
(Ibs)
2,500



10,000




10,000




10,000






Basis for
listing
b



a




a




a






Chemical name
Trimethylchlorosil-
ane [Silane,
chlorotrimethyl-].
Vinyl acetate
monomer [Ace-
tic acid ethenyl
ester].
CAS No.
75-77-4


108-05-4



Threshold
quantity
(Ibs)
10,000


15,000



Basis for
listing
b


b



                                                  1 The mixture exemption in §68.115(b)(1) does not apply to
                                                the substance.
                                                  NOTE: 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 hydro-
                                                gen chloride, and history of accidents.
                                                  e Toxicity of sulfur trioxide and sulfuric acid, potential to
                                                release sulfur trioxide, and history of accidents.
 TABLE 2 TO §68.130.—LIST OF REGULATED Toxic SUBSTANCES AND THRESHOLD QUANTITIES FOR
                              ACCIDENTAL RELEASE PREVENTION
                                 [CAS Number Order—77 Substances]
CAS No.
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 	
1 07-02-8
107-11-9
107-12-0 	
1 07-1 3-1
107-15-3 	
107-18-6 	
1 07-30-2
108-05-4 	
108-23-6 	
108-91-8
109-61-5 	
1 1 0-00-9
110-89-4 	
123-73-9 	
Chemical name

1,1-Dimethylhydrazine [Hydrazine, 1,1-dimethyl-] 	
Methyl hydrazine [Hydrazine, methyl-] 	
Methyl chloride [Methane, chloro-] 	

Carbon disulfide 	
Phosgene [Carbonic dichloride] 	
Propyleneimine [Aziridine, 2-methyl-] 	
Propylene oxide [Oxirane, methyl-] 	
Tetramethyllead [Plumbane, tetramethyl-] 	
Trimethylchlorosilane [Silane, chlorotrimethyl-] 	
Methyltrichlorosilane [Silane, trichloromethyl-] 	
Peracetic acid [Ethaneperoxoic acid] 	
Methyl chloroformate [Carbonochloridic acid, methylester] 	
Epichlorohydrin [Oxirane, (chloromethyl)-] 	

Propionitrile [Propanenitrile] 	
Ethylenediamine [1,2-Ethanediamine] 	
Allyl alcohol [2-Propen-1-ol] 	
Vinyl acetate monomer [Acetic acid ethenyl ester] 	
Isopropyl chloroformate [Carbonochloridic acid, 1-methylethyl ester] 	
Propyl chloroformate [Carbonochloridic acid, propylester] 	
Piperidine 	
Crotonaldehvde. fD- F2-Butenal. fD-1 	
Threshold
quantity
(Ibs)
15000
15,000
15,000
20000
10,000
2500
10000
20,000
10000
500
10,000
10,000
10,000
10,000
5000
5,000
20000
10,000
5,000
10000
20,000
5000
10000
10,000
20000
20,000
15,000
5000
15,000
15,000
15000
15,000
5000
15,000
20.000
Basis for
listing
b
b
b
b
a
a b
b
b
a b
a, b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
                                             59

-------
§68.130
40 CFR Ch. I (7-1-98 Edition)
 TABLE 2 TO §68.130.—LIST OF REGULATED Toxic SUBSTANCES AND THRESHOLD QUANTITIES FOR
                         ACCIDENTAL RELEASE PREVENTION—Continued
                                  [CAS Number Order—77 Substances]
CAS No.
126-98-7 	
151-56-4 	
302-01-2
353-42-4
506-77-4 	
509-1 4-8
542-88-1 	
556-64-9 	
584-84-9
594-42-3 	
624-83-9
81 4-68-6
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
7782-41^1 	
7782-50-5
7783-06^1
7783-07-5 	
7783-60-0
7784-34-1 	
7784-42-1 	
7803-51-2
8014-95-7 	
1 0025-87-3
10049-04-4 	
10102-43-9 	
1 0294-34-5
13463-39-3 	
13463-40-6 	
1 9287-45-7
26471-62-5 	
Chemical name
Methacrylonitrile [2-Propenenitrile, 2-methyl-] 	
Ethyleneimine [Aziridine] 	

trifluoro[oxybis[methane]]-, T-4-.
Cyanogen chloride 	
Chloromethyl ether [Methane, oxybis[chloro-] 	
Methyl thiocyanate [Thiocyanic acid, methyl ester] 	
Perchloromethylmercaptan [Methanesulfenyl chloride, trichloro-] 	

Crotonaldehyde [2-Butenal] 	
Sulfur trioxide 	
Titanium tetrachloride [Titanium chloride (TICI4) (T-4)-] 	
Hydrochloric acid (cone 37% or greater) 	

Ammonia (anhydrous) 	
Nitric acid (cone 80% or greater) 	
Phosphorus trichloride [Phosphorous trichloride] 	
Fluorine 	

Hydrogen selenide 	
Sulfur tetrafluoride [Sulfur fluoride (SF4) (T-4)-]
Arsenous trichloride 	
Arsine 	
Oleum (Fuming Sulfuric acid) [Sulfuric acid, mixture with sulfur trioxide]1 	
Chlorine dioxide [Chlorine oxide (CIO2)] 	
Nitric oxide [Nitrogen oxide (NO)] 	
Nickel carbonyl 	
Iron, pentacarbonyl- [Iron carbonyl (Fe(CO)5), (TB-5-11)-] 	
Toluene diisocyanate (unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-
1]1.
Threshold
quantity
(Ibs)
10,000
10,000
15000
15000
10,000
10000
1,000
20,000
10000
10,000
10000
5000
20,000
5000
10,000
2,500
5000
15,000
5000
1 000
10,000
20000
15,000
15,000
10000
1,000
2500
10000
500
2500
15,000
1,000
5000
10,000
5000
1,000
10,000
5000
1,000
2,500
2500
10,000
Basis for
listing
b
b
b
b
c
b
b
b
b
a b
b
b
a b
a, b
b
b
d
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.
  NOTE: 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.


 TABLE 3 TO §68.130.—LIST OF REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES

                             FOR ACCIDENTAL RELEASE PREVENTION

                                  [Alphabetical Order—63 Substances]
Chemical name

Acetylene [Ethyne] 	
Bromotrif luorethylene [Ethene, bromotrif luoro-] 	
Butane 	
2-Butene
Butene 	
CAS No.
75_07-0
74-86-2
598-73-2
1 06-99-0
106-97-8
1 06-98-9
107-01-7
25167-67-3
Threshold
quantity
(Ibs)
10000
10,000
10,000
10000
10,000
10000
10000
10,000
Basis for
listing

f
f
f
f
f
f
f
                                               60

-------
Environmental Protection Agency
§68.130
 TABLE 3 TO §68.130.—LIST OF REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES
                     FOR ACCIDENTAL RELEASE PREVENTION—Continued
                               [Alphabetical Order—63 Substances]
Chemical name
2-Butene-cis 	
2-Butene-trans [2-Butene (E)]

Chlorine monoxide [Chlorine oxide] 	
2-Chloropropylene [1-Propene, 2-chloro-] 	

Cyclopropane 	
Dichlorosilane [Silane, dichloro-] 	

2,2-Dimethylpropane [Propane, 2,2-dimethyl-] 	
Ethane 	

Ethyl chloride [Ethane, chloro-] 	
Ethylene [Ethene] 	

Ethyl nitrite [Nitrous acid, ethyl ester] 	
Hydrogen 	

Isoprene [1,3-Butadinene, 2-methyl-] 	
Isopropylamine [2-Propanamine] 	

Methylamine [Methanamine] 	
3-Methyl-1-butene 	
2-Methyl-1-butene

Methyl formate [Formic acid, methyl ester] 	
2-Methylpropene [1-Propene, 2-methyl-] 	

1-Pentene 	
2-Pentene, (E)- 	
2-Pentene (Z)-

Propane 	
Propylene [1-Propene] 	

Tetrafluoroethylene [Ethene, tetrafluoro-] 	
Tetramethylsilane [Silane, tetramethyl-] 	

Trimethylamine [Methanamine, N,N-dimethyl-] 	
Vinyl acetylene [1-Buten-3-yne] 	

Vinyl fluoride [Ethene, fluoro-] 	
Vinylidene chloride [Ethene, 1,1-dichloro-] 	
Vinvl methvl ether FEthene. methoxv-1 	
CAS No.
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
1 24^10-3
463-82-1
74-84-0
1 07-00-6
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
1 09-66-0
109-67-1
646-04-8
627-20-3
463-49-0
74-98-6
115-07-1
74_gg_7
7803-62-5
116-14-3
75-76-3
1 0025-78-2
79-38-9
75-50-3
689-97-4
75-01-4
1 09-92-2
75-02-5
75-35-4
75-38-7
107-25-5
Threshold
quantity
(Ibs)
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10000
10,000
10,000
10000
10.000
Basis for
listing
f
f
f
f
g
f
f
f
f
f
f
f
f
f
f
f

f
f
f

g
g
f
f
f
f
g
f
f

g
g
f
f
f
f
f
f
g
f
f
f
a f

f
g
f
f
 NOTE: Basis for Listing:
 a  Mandated for listing by Congress.
 f Flammable gas.
 g  Volatile flammable liquid.
                                          61

-------
§68.130
40 CFR Ch. I  (7-1-98  Edition)
 TABLE 4 TO §68.130.—LIST OF REGULATED FLAMMABLE  SUBSTANCES AND THRESHOLD QUANTITIES
                                 FOR ACCIDENTAL RELEASE  PREVENTION
                                      [CAS Number Order—63 Substances]
                                        Chemical name
                                                                             CAS No.
                  Threshold
                   quantity
                     (Ibs)
 Basis for
   listing
60-29-7 	  Ethyl ether [Ethane, 1,1'-oxybis-] 	       60-29-7
74-82-8 	  Methane 	       74-82-8
74-84-0 	  Ethane  	       74-84-0
74-85-1 	  Ethylene [Ethene] 	       74-85-1
74-86-2 	  Acetylene [Ethyne] 	       74-86-2
74-89-5 	  Methylamine [Methanamine] 	       74-89-5
74-98-6 	  Propane 	       74-98-6
74-99-7 	  Propyne [1-Propyne]  	       74-99-7
75-00-3 	  Ethyl chloride [Ethane, chloro-] 	       75-00-3
75-01-4 	  Vinyl chloride [Ethene, chloro-j 	       75-01-4
75-02-5 	  Vinyl fluoride [Ethene, fluoro-] 	       75-02-5
75-04-7 	  Ethylamine [Ethanamine] 	       75-04-7
75-07-0 	  Acetaldehyde	       75-07-0
75-08-1 	  Ethyl mercaptan [Ethanethiol] 	       75-08-1
75-19-4 	  Cyclopropane 	       75-19-4
75-28-5 	  Isobutane [Propane, 2-methyl]  	       75-28-5
75-29-6 	  Isopropyl chloride [Propane, 2-chloro-] 	       75-29-6
75-31-0 	  Isopropylamine [2-Propanamine]  	       75-31-0
75-35-4 	  Vinylidene chloride [Ethene, 1,1-dichloro-]  	       75-35-4
75-37-6 	  Difluoroethane [Ethane, 1,1-difluoro-] 	       75-37-6
75-38-7 	  Vinylidene fluoride [Ethene, 1,1-difluoro-] 	       75-38-7
75-50-3 	  Trimethylamine [Methanamine, N, N-dimethyl-] 	       75-50-3
75-76-3 	  Tetramethylsilane [Silane, tetramethyl-] 	       75-76-3
78-78-4 	  Isopentane [Butane, 2-methyl-] 	       78-78-4
78-79-5 	  Isoprene [1,3,-Butadiene, 2-methyl-] 	       78-79-5
79-38-9 	  Trifluorochloroethylene [Ethene, chlorotrifluoro-] 	       79-38-9
106-97-8 	  Butane  	      106-97-8
106-98-9 	  1-Butene 	      106-98-9
196-99-0 	  1,3-Butadiene 	      106-99-0
107-00-6 	  Ethyl acetylene [1-Butyne]  	      107-00-6
107-01-7 	  2-Butene 	      107-01-7
107-25-5 	  Vinyl methyl ether [Ethene,  methoxy-] 	      107-25-5
107-31-3 	  Methyl formate  [Formic acid, methyl ester]  	      107-31-3
109-66-0 	  Pentane 	      109-66-0
109-67-1 	  1-Pentene 	      109-67-1
109-92-2 	  Vinyl ethyl ether [Ethene, ethoxy-] 	      109-92-2
109-95-5 	  Ethyl nitrite [Nitrous acid, ethyl ester] 	      109-95-5
115-07-1 	  Propylene [1-Propene] 	      115-07-1
115-10-6 	  Methyl ether [Methane, oxybis-] 	      115-10-6
115-11-7 	  2-Methylpropene [1-Propene, 2-methyl-]  	      115-11-7
116-14-3 	  Tetrafluoroethylene [Ethene, tetrafluoro-] 	      116-14-3
124-40-3 	  Dimethylamine  [Methanamine,  N-methyl-] 	      124-40-3
460-19-5 	  Cyanogen [Ethanedinitrile]  	      460-19-5
463-49-0 	  Propadiene  [1,2-Propadiene] 	      463-49-0
463-58-1 	  Carbon  oxysulfide [Carbon  oxide sulfide (COS)] 	      463-58-1
463-82-1 	  2,2-Dimethylpropane [Propane, 2,2-dimethyl-]  	      463-82-1
504-60-9 	  1,3-Pentadiene 	      504-60-9
557-98-2 	  2-Chloropropylene [1-Propene, 2-chloro-] 	      557-98-2
563-45-1 	  3-Methyl-1-butene 	      563-45-1
563-46-2 	  2-Methyl-1-butene 	      563-46-2
590-18-1 	  2-Butene-cis 	      590-18-1
590-21-6 	  1-Chloropropylene [1-Propene, 1-chloro-] 	      590-21-6
598-73-2 	  Bromotrifluorethylene [Ethene,  bromotrifluoro-] 	      598-73-2
624-64-6 	  2-Butene-trans  [2-Butene, (E)]  	      624-64-6
627-20-3 	  2-Pentene, (Z)- 	      627-20-3
646-04-8 	  2-Pentene, (E)- 	      646-04-8
689-97-4 	  Vinyl acetylene [1-Buten-3-yne] 	      689-97-4
1333-74-0  	  Hydrogen 	     1333-74-0
4109-96-0  	  Dichlorosilane [Silane, dichloro-] 	     4109-96-0
7791-21-1  	  Chlorine monoxide [Chlorine oxide] 	     7791-21-1
7803-62-5  	  Silane  	     7803-62-5
10025-78-2 	  Trichlorosilane[Silane,trichloro-] 	    10025-78-2
25167-67-3 	  Butene  	    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
  Note: Basis for Listing:    a  Mandated for listing by Congress.    f  Flammable gas.    g  Volatile flammable liquid.

[59 FR 4493, Jan. 31, 1994. Redeslgnated at 61  FR 31717, June 20, 1996, as amended at 62 FR 45132,
Aug. 25, 1997; 63 FR 645,  Jan. 6, 1998]
                                                     62

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Environmental Protection Agency
                              §68.165
   Sub pa it G—Risk Management
                 Plan

  SOURCE: 61 FR 31726, June 20, 1996,  unless
otherwise noted.

§ 68.150   Submission.
  (a) The owner  or operator shall sub-
mit a single RMP that includes the in-
formation  required by §§68.155 through
68.185 for  all  covered processes. The
RMP shall be  submitted in a method
and format to a central point as  speci-
fied by EPA prior to June 21, 1999.
  (b) The owner  or operator shall sub-
mit 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  ex-
clude classified information. Subject to
appropriate procedures to protect such
information from  public  disclosure,
classified data or information excluded
from the RMP may be made available
in a classified annex to the RMP for re-
view by  Federal  and state  representa-
tives who  have   received  the  appro-
priate security clearances.

§68.155   Executive summary.
  The owner or operator shall provide
in the RMP an executive summary that
includes  a brief description of the fol-
lowing elements:
  (a) The accidental release prevention
and emergency response policies at the
stationary source;
  (b) The stationary source and regu-
lated substances handled;
  (c) The worst-case release scenario(s)
and the alternative release  scenario(s),
including administrative controls and
mitigation  measures to limit the dis-
tances for each reported scenario;
  (d)  The  general  accidental  release
prevention  program and  chemical-spe-
cific prevention steps;
  (e) The five-year accident history;
  (f) The emergency response program;
and
  (g) Planned changes to improve safe-
ty.

§ 68.160 Registration.
  (a) The owner or operator shall com-
plete a single registration form and in-
clude  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  Bradstreet
number of the  corporate parent com-
pany;
  (4) The name, telephone number, and
mailing address of the  owner or opera-
tor;
  (5) The name  and title of the  person
or position with overall responsibility
for RMP elements and implementation;
  (6) The  name, title,  telephone num-
ber,  and 24-hour telephone  number  of
the emergency contact;
  (7) For  each covered  process, the
name  and  CAS  number  of  each regu-
lated substance held above the thresh-
old  quantity in the process, the maxi-
mum quantity  of each regulated sub-
stance 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  identi-
fier;
  (9) The number  of full-time employ-
ees  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  in-
spection of the  stationary source by a
Federal,  state,  or  local government
agency and the  identity of the inspect-
ing entity.

§68.165 Offsite consequence analysis.
  (a) The  owner or operator shall sub-
mit in  the RMP information:
                                      63

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§68.168
          40 CFR Ch. I  (7-1-98 Edition)
  (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 rep-
resent all regulated  toxic  substances
held above the threshold quantity and
one worst-case release scenario to rep-
resent all  regulated  flammable  sub-
stances held above the threshold quan-
tity. If additional worst-case scenarios
for toxics or flammables are  required
by §68.25(a)(2)(iii), the owner or opera-
tor 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  rep-
resent all  regulated  flammable  sub-
stances held above the threshold quan-
tity.
  (b) The  owner or  operator shall sub-
mit 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 gas
release, or  liquid  spill and vaporiza-
tion);
  (5) Quantity released in pounds;
  (6) Release rate;
  (7) Release duration;
  (8) Wind speed and  atmospheric sta-
bility class (toxics only);
  (9) Topography (toxics only);
  (10) Distance to endpoint;
  (11) Public and environmental recep-
tors within the distance;
  (12)  Passive mitigation  considered;
and
  (13) Active mitigation considered (al-
ternative  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  in
paragraphs  (b) through  (k) of this sec-
tion. If the same information applies to
more than  one covered  process,  the
owner or operator may provide the in-
formation only  once, but shall indicate
to which processes the information ap-
plies.
  (b) The SIC code for the process.
  (c)  The name(s) of the chemical(s)
covered.
  (d) The date  of the most recent re-
view or revision of the safety informa-
tion and a list of Federal or state regu-
lations  or  industry-specific   design
codes  and  standards  used  to  dem-
onstrate compliance with the safety in-
formation requirement.
  (e)  The date  of completion  of  the
most recent hazard review or update.
  (1) The expected date of completion
of any changes  resulting from the haz-
ard 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 re-
view.
  (f) The date of the most recent review
or revision of operating procedures.
  (g) The date  of the most recent re-
view 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 re-
view or revision of maintenance proce-
dures and the date of the most recent
equipment inspection or  test and  the
equipment inspected or tested.
  (i) The date of the  most recent com-
pliance audit and the expected date of
completion  of  any changes resulting
from the compliance audit.
  (j) The date of the most recent inci-
dent  investigation  and  the  expected
date of completion of any changes re-
sulting from the investigation.
  (k)  The  date of  the   most  recent
change that triggered a review or revi-
sion of safety information, the  hazard
review, operating or  maintenance pro-
cedures,  or training.
                                      64

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Environmental Protection Agency
                              §68.190
§68.175  Prevention  program/Program
    3.
  (a) For each Program 3 process, the
owner  or operator shall provide the in-
formation  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  only
once, but shall indicate to which proc-
esses 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 in-
formation 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 re-
view 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 re-
view or revision of maintenance  proce-
dures 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 the
most recent review or revision of man-
agement of change procedures.
  (j) The date of the most recent pre-
startup review.
  (k) The date of the most recent com-
pliance audit and the expected date of
completion of any changes  resulting
from the compliance audit;
  (1) The date of the most recent inci-
dent investigation  and  the expected
date of completion of any changes re-
sulting from the investigation;
  (m) The  date  of the most recent re-
view or revision of employee participa-
tion plans;
  (n) The date of the most recent re-
view or  revision  of  hot work permit
procedures;
  (o) The date of the most recent re-
view or  revision  of  contractor  safety
procedures; and
  (p) The date of the most recent eval-
uation of contractor safety perform-
ance.

§68.180  Emergency response program.
  (a) The owner or operator shall pro-
vide in the RMP the following informa-
tion:
  (1) Do you  have a written emergency
response plan?
  (2) Does the plan include specific ac-
tions to be taken  in response to an ac-
cidental  releases  of a  regulated  sub-
stance?
  (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 re-
view or  update of the  emergency re-
sponse plan;
  (6) The date of the most recent emer-
gency response training for employees.
  (b) The owner or operator shall pro-
vide 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 the
RMP the certification statement pro-
vided in§68.12(b)(4).
  (b) For all other  covered processes,
the owner or operator shall submit in
the RMP  a single  certification that, to
the best  of the signer's  knowledge, in-
formation, and belief formed after rea-
sonable inquiry,  the information sub-
mitted is true,  accurate, and complete.

§68.190  Updates.
  (a) The owner  or operator shall re-
view and update  the RMP as specified
in paragraph (b)  of this  section and
submit it in  a method and format to a
                                      65

-------
§68.200
          40 CFR Ch. I  (7-1-98 Edition)
central point specified by EPA prior to
June 21, 1999.
  (b) The owner or operator of a sta-
tionary source shall revise and update
the RMP submitted under §68.150  as
follows:
  (1) Within five years of its initial sub-
mission 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 a
newly  regulated substance  is first list-
ed 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 change
that requires  a  revised  offsite  con-
sequence analysis as provided in §68.36;
and
  (7) Within six  months of  a change
that alters the Program level that ap-
plied to any covered process.
  (c) If a stationary source  is no longer
subject to this part, the owner or oper-
ator shall submit  a revised  registration
to  EPA within  six months indicating
that the stationary source  is no longer
covered.

  Subpart H—Other Requirements

  SOURCE: 61  FR 31728, June 20, 1996,  unless
otherwise noted.

§68.200 Recordkeeping.
  The owner or operator shall maintain
records supporting the  implementation
of this part  for five years unless other-
wise 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  infor-
mation by the Department of Defense
or  other Federal  agencies  or contrac-
tors of such  agencies  shall be  con-
trolled by applicable laws, regulations,
or executive orders concerning the re-
lease of classified information.

§68.215  Permit content  and  air  per-
    mitting   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 meet-
ing the  requirements of this part by
the date  provided in §68.10(a) or;
  (ii) As  part of the compliance certifi-
cation   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  sub-
mit any additional relevant informa-
tion requested by the air permitting
authority or designated agency.
  (c) For 40  CFR part 70 or part 71 per-
mits issued  prior  to  the deadline for
registering  and submitting the  RMP
and which do not contain permit condi-
tions described in paragraph (a) of this
section,  the  owner or operator  or air
permitting authority shall initiate per-
mit 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 au-
thority 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 any
delegation instrument shall be  main-
tained by the air permitting authority.
The state may enter  a written  agree-
ment 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:
                                      66

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Environmental Protection Agency
                              §68.220
  (1) Verify that  the source owner  or
operator has registered and submitted
an  RMP  or a  revised  plan when re-
quired by this part;
  (2) Verify that  the source owner  or
operator  has  submitted  a source cer-
tification or in  its absence has submit-
ted a  compliance schedule consistent
with paragraph  (a) (2) of this section;
  (3) For some or all of the sources sub-
ject to this section, use  one or more
mechanisms such as, but  not limited
to,  a completeness  check,  source au-
dits, record reviews,  or facility inspec-
tions to ensure  that  permitted sources
are  in  compliance  with  the require-
ments of this part; and
  (4) Initiate enforcement action based
on  paragraphs  (e)(l)  and  (e)(2) of this
section as appropriate.

§68.220  Audits.
  (a) In addition to  inspections for the
purpose of regulatory development and
enforcement of the Act,  the  imple-
menting   agency  shall   periodically
audit RMPs submitted  under subpart G
of this part to  review  the adequacy  of
such  RMPs  and  require  revisions  of
RMPs  when necessary to ensure com-
pliance 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 station-
ary sources in the same industry;
  (3) Quantity of regulated substances
present at the stationary source;
  (4) Location of the stationary source
and its proximity to the public and en-
vironmental receptors;
  (5) The  presence of specific regulated
substances;
  (6)  The hazards  identified  in the
RMP; and
  (7) A plan providing for neutral, ran-
dom oversight.
  (c) Exemption from audits. A station-
ary source with a Star or Merit rank-
ing 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
area where an accidental release could
occur.
  (e)  Based on  the audit, the imple-
menting 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 the
basis  for the revisions, reflecting indus-
try standards and  guidelines  (such  as
AIChE/CCPS guidelines and ASME and
API standards) to the  extent that such
standards and  guidelines  are  applica-
ble, and shall include a timetable for
their  implementation.
  (f)  Written response to a preliminary de-
termination. (1) The owner or  operator
shall  respond  in  writing to  a prelimi-
nary  determination  made in  accord-
ance with paragraph (e) of this section.
The response shall state the owner  or
operator will  implement the revisions
contained  in  the  preliminary  deter-
mination in accordance with the time-
table  included in the preliminary  de-
termination  or  shall state  that the
owner or operator rejects the revisions
in whole or in part. For each rejected
revision, the owner or  operator  shall
explain the basis for rejecting such re-
vision.  Such explanation  may include
substitute revisions.
  (2) The written response under para-
graph (f)(l) of this section shall be re-
ceived  by  the  implementing  agency
within 90 days of the  issue of the pre-
liminary determination or  a  shorter
period  of  time  as  the  implementing
agency  specifies in the preliminary de-
termination  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 implementing
agency  may  provide  in writing  addi-
tional time for the response to be re-
ceived.
  (g) After providing the owner or oper-
ator an opportunity to  respond under
paragraph (f) of this section, the imple-
menting agency  may  issue  the owner
or operator a  written  final determina-
tion of necessary revisions to the sta-
tionary source's RMP. The final deter-
mination may adopt or modify the re-
visions  contained  in  the  preliminary
                                      67

-------
§68.220

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 owner
or  operator shall  include  an  expla-
nation of the basis  for the revision. A
final determination that fails  to adopt
a  substitute  revision provided under
paragraph  (f) of this section  shall in-
clude an explanation of  the basis for
finding such substitute revision unrea-
sonable.
  (h) Thirty days after  completion  of
the actions detailed in the  implemen-
tation schedule set in the final deter-
mination 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 required
by the final  determination,  and  sub-
mits  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 pre-
clude,  limit,  or interfere  in any  way
with the authority of EPA or the state
to exercise its enforcement, investiga-
tory, and  information gathering au-
thorities  concerning this  part  under
the Act.
                                      68

-------
Environmental Protection Agency
Pt. 68, App. A
Toxic end-
point (mg/L)
Chemical name
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Allyl alcohol [2-Propen-1-ol] 	


























































































































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Chloroform [Methane, trichloro-] 	
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Chloromethyl methyl ether [Methane, chlorom
Crotonaldehyde [2-Butenal] 	
Crotonaldehyde, (E)-, [2-Butenal, (E)-] 	
Cyanogen chloride 	
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Hydrochloric acid (cone 37% or greater) 	
Hydrocyanic acid 	
Hydrogen chloride (anhydrous) [Hydrochloric
Hydrogen fluoride/Hydrofluoric acid (cone 50°;
Hydrogen selenide 	
















































Iron, pentacarbonyl- [Iron carbonyl (Fe(CO)5), (TB-5-11)-]




















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                                   69

-------
Pt. 68, App. A
40 CFR Ch. I (7-1-98 Edition)
o
1
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 a
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point (mg/L)
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Methyl chloroformate [Carbonochloridic acid, methylester]



















































Methyl isocyanate [Methane, isocyanato-] 	






































































































Methyl thiocyanate [Thiocyanic acid, methyl ester] 	
Methyltrichlorosilane [Silane, trichloromethyl-] 	



















































Nitric acid (cone 80% or greater) 	
Nitric nxidp FNitrnnpn nxidp nMOYI



































































































Oleum (Fuming Sulfuric acid) [Sulfuric acid, mixture with s
Peracetic acid [Ethaneperoxoic acid] 	
Perchloromethylmercaptan [Methanesulfenyl chloride, trich
Phosgene [Carbonic dichloride] 	





































































Phosphorus oxychloride [Phosphoryl chloride] 	
Phosphorus trichloride [Phosphorous trichloride] 	
























































































































Propionitrile [Propanenitrile] 	
Propyl chloroformate [Carbonochloridic acid, propylester] .
Propyleneimine [Aziridine, 2-methyl-] 	



















































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Tetramethyllead [Plumbane, tetramethyl-] 	
















































; ^r1^


Titanium tetrachloride [Titanium chloride (TiCI4) (T-4)-] ....
Toluene 2,4-diisocyanate [Benzene, 2,4-diisocyanato-1-me






































Toluene diisocyanate (unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-] .






































Vinyl acetate monomer [Acetic acid ethenyl ester] 	


















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: : 1 CM 1 1^ : :CMICM : IT) O CD : O 1
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co T- T IT- I co co r^ T to o i to T- CQ CM I I I CD CD CD o T- T- I m I r^ co T I
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1 1 l^i |co I ^r CD T— T— l^i IOOT— CDi^cD I I^TCQ^T icDLO^i l^r |co
70
                                                               T3
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-------
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

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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

Petroleum 	
Other Manufacturing  	
Agriculture  	
Public Sources 	
Utilities	
Other 	
Federal Sources	
                            Basic chemical manufacturing, petrochemicals, resins, agricultural chemicals, Pharmaceuticals,
                              paints, cleaning compounds.
                            Refineries.
                            Paper, electronics, semiconductors, fabricated metals, industrial machinery, food processors.
                            Agricultural retailers.
                            Drinking water and waste water treatment systems.
                            Electric utilities.
                            Propane retailers and users, cold storage, warehousing, and wholesalers.
                            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)(l) of the Clean Air Act (CAA) as
                           amended (42 U.S.C. 7412(r), 7601 (a)(l)).

                           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

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             Federal  Register/Vol.  64,  No. 3/Wednesday, January  6,  1999/Rules  and Regulations
                                                                        965
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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966
Federal Register/Vol.  64,  No. 3/Wednesday, January 6,  1999/Rules  and  Regulations
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)(l)
of Part 68 and one commenter partially
objected. Section 68.10(d)(l) 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)(l) uses industrial codes to
                          classify processes,  not facilities as a
                          whole. Since section 68.10(d)(l) 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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                                                                        967
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 (HE) will
volatilize more quickly than a spill of
the same quantity of HE 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 source
handles both regulated and non-
regulated 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 a
system for hot work  permits facility-
wide, 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.
  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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                                                                           969
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 as
possible. This approach of requiring up-
front 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 local
entities. Section 304 also requires a written follow-
up 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 the
comments EPA received on the CBI-
related 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
of40CFRPart68.151(b)(l)  the reference
to 40 CFR Part 68.160(b)(9), to allow for
the possibility of the number of full-
time 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  (sections
68.160(b)(l)-(6), (8)-(13)) and the five-
year 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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                                                                         971
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 indicate
the general health concerns from short-
term 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 to
release the data. Establishing an up-
front 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 information
function of RMPs, EPA believes that up-
front substantiation is clearly warranted

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for CBI claims made for RMP data. Up-
front 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)(l)).

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                                                                        973
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 data
will only rarely contain CBI,  and the up-
front 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)(l) 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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                                                                        975
  (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 etseq. 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 up-
front 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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                                                                        977
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 such
documentation, EPA believes that up-
front 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 and
adopt the least costly, most cost-
effective 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.

/. 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.
                    APPENDIX TO PREAMBLE—DATA ELEMENTS THAT MAY NOT BE CLAIMED AS CBI
               Rule element
                                                                             Comment
68.160(b)(1)  Stationary source name,  street,
  city, county, state, zip code, latitude, and lon-
  gitude, method for obtaining latitude and lon-
  gitude, and description  of location  that lati-
  tude and longitude represent.
68.160(b)(2)  Stationary  source Dun and  Brad-
  street 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 emer-
  gency contact.
68.160(b)(7) Program level and NAICS code of
  the process.
68.160(b)(8) The stationary source  EPA identi-
  fier.
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 num-
  ber.
                            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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             Federal  Register/Vol. 64, No. 3/Wednesday,  January 6, 1999/Rules and  Regulations
                                                                           979
              APPENDIX TO PREAMBLE—DATA ELEMENTS THAT MAY NOT BE CLAIMED AS CBI—Continued
               Rule element
                                                                             Comment
68.160(b)(13) The  date of the  last safety in-
  spection and the  identity of the inspecting en-
  tity.
68.165(b)(4) Basis  of the results  (give model
  name if used).
68.165(b)(9) Wind speed and atmospheric sta-
  bility 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 recep-
  tors 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 compli-
      ance dates and information.
68.180 Emergency response program  	
 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 re-
   veal chemical identity or quantity may be claimed as CBI.
 By itself, this information provides no confidential information. Other elements that would re-
   veal 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 infor-
   mation 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)(l) 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)(ll) 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)(l) 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 §68.1 65 (b) (4),  (b)(9), (b)(10),
  (3) Accident history data required by
§68.168;
  (4) Prevention program data required
by §68. 170 (b), (d), (e)(l),  (f) through (k);
  (5) Prevention program data required
by §68.175(b), (d), (e)(l),  (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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980
Federal Register/Vol. 64, No.  3/Wednesday, January  6,  1999/Rules  and  Regulations
  (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)(l), (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.
*    *    *    *     *

[FRDoc. 99-231 Filed 1-5-99; 8:45 am]
BILLING CODE 6560-50-P

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