April 2000

Disclaimer

It is important that the user understand the purpose and limitation of the "CAA Section 112(r) Frequently Asked Questions" file. The questions and answers are not intended to fully represent or be used in place of the regulations. These questions can be used to explore the application of the regulations in different scenarios or to shed light on complex issues. The answers provided are not rules nor are they binding upon the Agency in any context. The EPA may withdraw, modify, or depart from the answers provided in this file at any time without notice. For an understanding of the actual regulatory requirements in any given situation, the reader must consult the appropriate sections of Title 40 of the Code of Federal Regulations (CFR), pertinent Federal Registers and EPA guidance documents, as well as relevant State regulations.

CAA Questions and Answers

Table of Contents

I. General Duty
II. Applicability
    A. Amendments to List Rule (April 15, 1996)
    B. Exemptions
    C. DOT Transportation Regulations
III. Program Level Screening
IV. Hazard Assessment
    A. Offsite Consequence Analysis
    B. Worst-Case Release Scenario
    C. Alternative Release Scenario
    D. Modeling (inc. Meteorology)
    E. Defining offsite impacts - Populations Affected
    F. Defining offsite impacts - Environmental Impact
    G. Five-Year Accident History
V. Prevention Program
    A. Prevention Program - OSHA PSM
VI. Emergency Response Program
VII. Risk Management Plan (RMP)
    A. Registration / RMPlan Submission
    B. Model Risk Management Programs (*No questions)
VIII. Enforcement
IX. Implementation
    A. Implementation - Interaction with CAA Title V Programs
    B. Implementation - Audits
X. Miscellaneous

I. 1. Question: What is the general duty clause under CAA §112(r)(1)?

Answer: The CAA general duty clause directs owners and operators of stationary sources to identify hazards that may result from accidental releases, to design and maintain a safe facility, and to minimize the consequences of releases when they occur.

(CAA Q&A Database, October 1996)

I. 2. Question: For CAA section 112(r)(1), General Duty, what are the chemicals that are covered?

Answer: There is no specific list of substances which subject a stationary source owner or operator to the general duty provisions. The general duty provisions apply to owners and operators of all stationary sources which have any " extremely hazardous substances". Extremely hazardous substances are not limited to the list of regulated substances listed under section 112(r), nor the extremely hazardous substances under EPCRA §302 (40 CFR Part 355, Appendices A and B).

Although there is no definition for extremely hazardous, the Senate Report on the Clean Air Act provides criteria EPA may use to determine if a substance is extremely hazardous. The report expressed the intent that the term "extremely hazardous substance" would include any agent "which may or may not be listed or otherwise identified by any Government agency which may as the result of short-term exposures associated with releases to the air cause death, injury or property damage due to its toxicity, reactivity, flammability, volatility, or corrosivity" (Senate Committee on Environment and Public Works, Clean Air Act Amendments of 1989, Senate Report No. 228, 101st Congress, 1st Session 211 (1989) - "Senate Report").

As the Senate makes clear, "the release of any substance which causes death or serious injury because of its acute toxic effect or as a result of an explosion or fire or which causes substantial property damage by blast, fire, corrosion or other reaction would create a presumption that such substance is extremely hazardous." Senate Report at 211. Revisions to the list of regulated substances under CAA 112(r) do not affect the applicability of the general duty provisions.

(CAA Q&A Database, May 1997)

I. 3. Question: Does the exemption at 40 CFR 68.125 for "ammonia used as an agricultural nutrient, when held by farmers" apply to the CAA Section 112(r)(1) general duty clause?

Answer: No. The exemption for ammonia held by farmers for use as fertilizer applies only to the provisions of the risk management program regulations at 40 CFR Part 68. The general duty requirement is statutory rather than regulatory and is, therefore, not subject to the regulatory exemption at 40 CFR 68.125.

( CAA Q&A Database, July 1997)

I.4.Question: Will the general duty clause be delegated?

Answer: The general duty clause (CAA section 112(r)(1)) is not included in part 68 and, therefore, will not be delegated to States that have taken implementation of the RMP program. States, however, may adopt their own general duty clause under state law.

(CAA Q&A Database, March 1999)

[Back to Table of Contents]

II. 1. Question: Who is covered by CAA §112(r)(7)?

Answer: An owner or operator of a stationary source that has more than a threshold quantity of a regulated substance in a process (40 CFR §68.10). Underlined terms were defined in the List Rule.

(CAA Q&A Database, August 1996)

II. 2. Question: Does a chemical need to be in a process to be covered by the CAA §112(r) risk management program requirements?

Answer: The risk management program requirements apply to owners and operators of stationary sources that have more than a threshold quantity of a regulated substance contained in a process (40 CFR 68.115). The definition of process is very broad, and includes any use, storage, manufacturing, handling, on-site movement, or any combination of these activities.

(CAA Q&A Database, October 1996)

II. 3. Question: Are there any pending changes to the January 31, 1994, List Rule?

Answer: No.  The May 22, 1997 (62 FR 27992) proposed amendment to the list rule were finalized on August 25, 1997 (62 FR 45130).  The amendment changed the hydrochloric acid concentration cut-off from 30% to 37%.  The April 15, 1996 (61 FR 16606) proposed amendments to the list rule were finalized on January 6, 1998 (63 FR 640).  The amendments to the list rule included: delisting Division 1.1 explosives; exempting from threshold determination regulated flammable substances in gasoline used a fuel and in naturally occurring hydrocarbon mixtures prior to initial processing; exempting flammable mixtures that do not have a National Fire Protection Association (NFPA) flammability hazard rating of 4;  modifying the definition of stationary source to clarify that the term does not apply to transportation, storage incident to transportation and
does not apply to naturally occurring hydrocarbon reservoirs; and clarifying that the chemical accident prevention provisions do not apply to sources located on the Outer Continental Shelf .

(CAA Q&A Database, September 1998)

II. 4. Question: CAA §112(r)(3) provides EPA the authority to amend the list of regulated substances. Does EPA expect to add chemicals to the list of regulated substances in the near future?

Answer: At this time, EPA does not expect to add any chemicals to the list of regulated substances. The statute, however, requires that the list be reviewed at least every five years (CAA §112(r)(3)).

(CAA Q&A Database, October 1996)

II. 5. Question: Are the risk management program requirements under 40 CFR Part 68 applicable to federal facilities?

Answer: Yes. The requirements at 40 CFR Part 68 are applicable to an owner or operator of a stationary source that has more than a threshold quantity of a regulated substance in a process (40 CFR §68.10(a)). The definition of stationary source includes buildings, structures, equipment, installations, or substance emitting stationary activities which, belong to the same industrial group, which are located on one or more contiguous properties, which are under the control of the same person, and from which an accidental release may occur (40 CFR 68.3). The Clean Air Act Section 302(e) defines "person" as an individual, corporation, partnership, association, State, municipality, political subdivision of a State, and any agency, department, or instrumentality of the United States and any officer, agent, or employee thereof.

( CAA Q&A Database, July 1997 **revised from August 1996 Q&A)

II. 6. Question: A stationary source is subject to the OSHA process safety management standard (PSM) because it exceeds the OSHA PSM threshold for chlorine. The stationary source does not, however, exceed the threshold for chlorine (or any other regulated substances) in a process under the Risk Management Program regulations (40 CFR §68.130). Is the stationary source subject to the Risk Management Program, requirements?

Answer: No. A stationary source is subject to the Risk Management Program requirements only if it has more than a threshold quantity of a regulated substance in a process.

(CAA Q&A Database, August 1996)

II. 7. Question: Why are hydrochloric acid and hydrogen chloride listed separately in the List of Regulated Substances at 40 CFR §68.130?

Answer: The aqueous form (hydrochloric acid) and the anhydrous form of this chemical (hydrogen chloride) have been assigned different thresholds.

(CAA Q&A Database, March 2000)

II. 8. Question: A wastewater treatment plant generates methane through a natural digestion process, then stores and uses the methane as fuel. Under 40 CFR Part 68, must the owner or operator of this stationary source evaluate the amount of methane to determine whether more than a threshold amount is present in any process?

Answer: No. The Chemical Safety Information, Site Security, and Fuels Regulatory Relief Act, enacted on August 5, 1999, excluded flammable substances from coverage under the Risk Management Program when used as fuel or held for sale as fuel at a retail facility (the Act defines a retail facility as a stationary source at which more than one-half of the income is obtained from direct sales to end users or at which more than one-half of the fuel sold, by volume, is sold through a cylinder exchange program). Therefore methane used as fuel at a wastewater treatment plant is no longer covered by the Risk Management Program. Stationary sources, including wastewater treatment plants, holding regulated flammable substances that are not used as fuel and not held for sale as fuel at a retail facility are still covered by the RMP if more than a threshold quantity is present in a process.
(CAA Q&A Database, April 2000)

II. 9. Question: An owner or operator of a stationary source that has more than a threshold quantity of a regulated substance in a process must comply with the requirements of 40 CFR Part 68. How large would a pipe have to be to contain a threshold amount (10,000 pounds) of methane?

Answer: Assuming a methane gas density of 0.042 pounds per cubic foot, at 1 atm and 60 degrees F (Handbook of Compressed Gases, Compressed Gas Association), the volume occupied by 10,000 pounds of methane is 236,000 cubic feet at 1 atm; 47,000 cubic feet at 5 atm; and 24,000 cubic feet at 10 atm. For a pipe with a 2-inch diameter to contain 10,000 pounds of methane gas, it would have to be: 2,000 miles long at 1 atm; 400 miles long at 5 atm; or 200 miles long at 10 atm.

For a pipe with a 3-inch diameter to contain 10,000 pounds of methane gas, it would have to be:

900 miles long at 1 atm; 180 miles long at 5 atm; or 90 miles long at 10 atm.

For a pipe with a 4-inch diameter to contain 10,000 pounds of methane gas, it would have to be: 560 miles long at 1 atm; 111 miles at 5 atm; or 57 miles long at 10 atm.

(CAA Q&A Database, October 1996)

II. 10. Question: Would underground storage of a regulated substance listed at 40 CFR§68.130 subject a stationary source owner or operator to the risk management program regulations?

Answer: If more than a threshold quantity of a regulated substance is present in a process at a stationary source, the owner or operator of that source must comply with the risk management program regulations at 40 CFR Part 68. The definition of "process" includes storage of a regulated substance, and there is no general exemption for underground storage.

(CAA Q&A Database, January 1997)

II. 11. Question: Formaldehyde is listed as a regulated substance under 40 CFR §68.130 with the qualifier "(solution)." When determining whether a threshold amount of this substance exists in a process, should a person consider the weight of the entire solution, or simply the amount of formaldehyde in the solution? How are thresholds for other regulated toxic substances in mixtures determined?

Answer: The owner or operator of a stationary source need only consider the weight of the formaldehyde in the solution; not the entire weight of the mixture. This is the case for all listed toxic substances, including those with concentration qualifiers (i.e., "conc 80% or greater").

(CAA Q&A Database, January 1997)

II. 12. Question: Who is covered by the RMP rule under CAA §112(r)(7)?

Answer: Section 112(r) of the CAA contains several provisions. The two most relevant to the regulated community at this time are Sections 112(r)(1) and 112(r)(7). Owners and operators of stationary sources at which regulated or any other extremely hazardous substances are present in a process, regardless of the amount of the substance, are subject to the general duty clause in section 112(r)(1). In addition, owners or operators of stationary sources are also subject to the RMP rule, pursuant to Section 112(r)(7), for those processes which contain a regulated substance in more than a threshold amount.

(CAA Q&A Database, January 1997)

II. 13. Question: What is the definition of "process"?

Answer: Process, as defined at 40 CFR §68.3, means any activity involving a regulated substance, including any use, storage, manufacturing, handling, or on-site movement of such substances, or combination of these activities. Any group of vessels that are interconnected, or separate vessels that are located such that a regulated substance could be involved in a potential release, is considered a single process. The owner or operator of the stationary source must make a reasonable determination as to whether two or more vessels may be involved in the same accident, or whether a release from one vessel may be anticipated to lead to a release from another. The owner/operator should document his decision as to whether the individual vessels do or do not constitute a single process.

(CAA Q&A Database, January 1997)

II. 14. Question: Does the chlorine listing apply only to gaseous forms of chlorine?

Answer: There is no qualifier attached to the listing for chlorine (40 CFR §68.130). The listing, therefore, applies to chlorine (CAS number 7782-50-5), regardless of physical state.

(CAA Q&A Database, May 1997)

II. 15. Question: Can EPA on its own initiative add chemicals to the list, or must it receive a petition from an outside party first and then follow the petition process?

Answer: EPA may revise the list of regulated substances at the discretion of the Administrator or as a result of petitions. Modifications to the list must be made through a rulemaking in which EPA explains the basis for the modifications. All petitions to amend the list must be made in accordance with 40 CFR §68.120.

(CAA Q&A Database, May 1997)

II. 16. Question: When determining whether a threshold amount of a regulated substance is present in a process (e.g., a tank), must the owner or operator of a stationary source consider the total capacity of the process, or the actual amount of regulated substance contained in the process?

Answer: The threshold determination is based on the maximum actual amount of the regulated substance contained in a process at any one time (40 CFR §68.115; see also 58 Fed. Reg. 5102, 5114 (January 19, 1993)).

(CAA Q&A Database, May 1997)

II. 17. Question: A stationary source has a mixture containing 9,000 pounds of butane and 1,001 pounds of water in a process. The mixture meets the criteria for a National Fire Protection Association flammability rating of 4 (NFPA 4). Is this process covered under the RMP regulations?

Answer: Yes. Where the concentration of the regulated flammable substance in the mixture is one percent or more by weight of the mixture, the entire weight of the mixture must be applied toward the 10,000 pound threshold quantity for the flammable substance unless the owner or operator can demonstrate that the mixture itself does not have an NFPA flammability hazard rating of 4 (40 CFR 68.115(b)(2)).  Because this mixture does have an NFPA 4 rating and is present in a process
in an amount greater than the threshold quantity, the process is a covered process under the risk management program regulations at 40 CFR part 68.

(CAA Q&A Database, September 1998)

II. 18. Question: According to the definition of "process" at 40 CFR §68.3, any group of vessels that are interconnected is considered to be a single process. If a stationary source has two interconnected vessels and one contains 6,000 pounds of butane while the other contains 6,000 pounds of propane, is this a covered process under 40 CFR Part 68?

Answer: No. Although the two interconnected vessels are considered a single process, in order for that process to be subject to the risk management program regulations it must contain more than a threshold quantity of a regulated substance (40 CFR §68.10(a)). The threshold quantity for both butane and propane (and all other regulated flammable substances) is 10,000 pounds (40 CFR §68.130). The amounts of different regulated substances present in a single process need not be aggregated to determine whether a threshold is exceeded. If, at any time, more than 10,000 pounds of either butane or propane is present in a process, that process is covered by the regulations at 40 CFR Part 68. Although this process as described is not subject to part 68, it is subject to Section 112(r)(1), the general duty clause (See questions under General Duty Clause).

If butane and propane are present in a mixture in the process, then the threshold quantity must be calculated differently. Because a mixture of propane and butane would meet the NFPA 4 flammability criteria, the entire weight of the mixture needs to be treated as the regulated substance and added up to account for the threshold quantity. If there are additional vessels in the process that contain pure butane and/or propane, the weight of the mixture should be added to both the weight of the remaining butane and the weight of the remaining propane to determine whether either the threshold for propane or butane has been exceeded (40 CFR §68.115(b)(2)). For example, if 1,000 pounds of the 6,000 pounds of propane are mixed with the 6,000 pounds of butane to make a 7,000 pound mixture, then that 7,000 pound mixture would be treated as the regulated substance (both butane and propane) for threshold calculations. The 7,000 pound mixture would have to be added to the remaining 5,000 pounds of pure butane and the threshold for butane would be exceeded.

(CAA Q&A Database, May 1997)

II. 19. Question: Are agricultural facilities potentially subject to the risk management program requirements of 40 CFR Part 68?

Answer: Yes. Although there is one specific exemption from the provisions of 40 CFR Part 68 for ammonia held by a farmer for use as an agricultural nutrient (40 CFR §68.125), there is no general exemption from the risk management program regulations for farms. If fertilizers, pesticides, or any other materials present at a farm are (or contain) regulated substances in excess of the applicable threshold quantity, the facility must comply with the requirements of 40 CFR Part 68. Ammonia held for distribution at a farm would not be exempt. In addition, even if a farmer is exempt from the Risk Management Plan rule, he is still subject to the General Duty Clause under CAA §112(r)(1) (see questions under General Duty Clause)

(CAA Q&A Database, May 1997)

II. 20. Question: The list of regulated toxic substances at 40 CFR Section 68.130 includes both "ammonia (anhydrous)" and "ammonia (conc 20% or greater)," but does not include a specific listing for "ammonium hydroxide." The Chemical Abstract Registry Service (CAS) number for ammonium hydroxide is 1336-21-6, and the CAS number for ammonia is 7664-41-7. Ammonium hydroxide is, however, simply a mixture of ammonia and water. Must a stationary source owner or operator consider the amount of ammonia present in ammonium hydroxide that is contained in a process when determining whether the threshold for ammonia is exceeded?

Answer: Yes. For the purposes of the risk management program regulations at 40 CFR Part 68, ammonium hydroxide must be treated as a solution of ammonia and water, regardless of the fact that ammonium hydroxide may be identified by a unique CAS number. The Agency has made it clear that the listing for "ammonia (conc 20% or greater)" applies to aqueous solutions of ammonia (List Rule Response to Comments document, page 50). If the concentration of ammonia in the ammonium hydroxide is 20% or greater, then the mixture is subject to threshold determination for "ammonia (conc 20% or greater)" under 40 CFR Section 68.115.

( CAA Q&A Database, July 1997)

II. 21. Question: The list of regulated substances at 40 CFR Section 130 includes aqueous ammonia that is at a concentration of 20 percent (by weight) or greater. Why did EPA select 20 percent as the concentration cut-off value?

Answer: Commonly used commodity solutions of ammonia (which mean the bulk shipments, not bottles of ammonia you can buy in the supermarket which are considerably more dilute) usually contain at least 20 percent ammonia by weight. The 20 percent concentration cut-off was proposed for regulation so that these solutions would be covered by the risk management program regulations (58 FR 5110; January 19, 1993). EPA did not revise the concentration cutoff in the final rule because such solution exceeded the volatility criterion of the final rule (59 FR 4488; January 31, 1994).

( CAA Q&A Database, July 1997)

II. 22. Question: Several toxic substances are listed as a regulated substances under 40 CFR §68.130 with concentration qualifiers (e.g., "conc 37% or greater"). What does this concentration mean? When determining whether a threshold amount of these substances exists in a process, should I consider the weight of the entire solution, or simply the amount of the regulated toxic substance in the solution?

Answer: If a regulated substance has a specific concentration listed, you need only consider solutions/mixtures with concentrations of the regulated substance that are at or above this concentration. You do not need to consider solutions/mixtures with concentrations of a regulated substance below the listed concentration when you determine threshold quantities. Examples: Ammonia has a specified concentration of 20%. Hence, you do not need to consider a 15 percent ammonia solution, but do need to account for a 25 percent ammonia solution. For any regulated substance without a listed concentration cutoff, you must consider the quantity of the regulated substance if the concentration exceeds one percent.

Once you have determined that the solution/mixture must be accounted for, you need to determine whether you exceed the threshold quantity. For regulated toxic substances, you must consider only the weight of the regulated substance in the solution/mixture towards the threshold quantity. Examples: The Threshold Quantity for ammonia solutions is 20,000 pounds. If you have more than 100,000 total pounds of a 20% ammonia solution, then you would have more than 20,000 pounds of ammonia in the solution and would have more than a threshold quantity. Similarly, if you have more than 50,000 total pounds of a 40% solution, you would also have more than a threshold quantity.

There are four regulated substances that have concentration qualifiers:

Ammonia (conc 20% or greater)

Hydrochloric acid (conc 37% or greater) see NOTE

Hydrogen fluoride/hydrofluoric acid (conc 50% or greater)

Nitric acid (conc 80% or greater)

( CAA Q&A Database, July 1997)

II. 23. Question: A stationary source has a mixture above the threshold. At standard temperature and pressure, the mixture does not meet the criteria for a National Fire Protection Association flammability rating of 4 (NFPA 4). At elevated temperatures and pressures, however, the mixture meets the NFPA 4 criteria. Is this process covered under the risk management program regulations?

Answer: No. The determination of whether a substance or mixture meets the NFPA 4 hazard rating is made in accordance with the definition of flammability hazard rating 4 in the NFPA 704, Standard System for the Identification of the Fire Hazards of Materials, and boiling point and flash point shall be defined and determined in accordance with NFPA 321, Standard on the Basic Classification of Flammable and Combustible Liquids. Standard (or ambient) temperatures and pressures are referenced in these standards. Although this mixture as described is not subject to part 68, it is subject to Section 112(r)(1), the general duty clause (See questions under General Duty Clause).

( CAA Q&A Database, July 1997)

II. 24. Question: The list of regulated substances under the chemical accident prevention provisions is found at 40 CFR Part 68. How did EPA select the substances to be included in this list?

Answer: The chemical accident prevention provisions promulgated pursuant to Section 112(r) of the Clean Air Act (CAA) are designed to focus on chemicals that pose a significant hazard to the community in the event of an accidental release, and to prevent and minimize the consequences of such releases (59 FR 4479; January 31, 1994). EPA was required by CAA Section 112(r)(3) to promulgate an initial list of at least 100 regulated substances that are known to cause or may reasonably be anticipated to cause death, injury, or serious adverse effects to human health or the environment if accidentally released. Congress required the inclusion of sixteen specific toxic substances on the initial list: chlorine, ammonia, anhydrous ammonia, methyl chloride, ethylene oxide, vinyl chloride, methyl isocyanate, hydrogen cyanide, hydrogen sulfide, toluene diisocyanate, phosgene, bromine, anhydrous hydrogen chloride, hydrogen fluoride, anhydrous sulfur dioxide, and sulfur trioxide (CAA Section 112(r)(3)). Additional toxic substances were included on the list based on toxicity, physical state, vapor pressure, production volume, and accident history. Commercially produced flammable gases and volatile flammable liquids were listed on the basis of flash point and boiling point criteria used by the National Fire Protection Association for its highest flammability hazard ranking (59 FR 4480; January 31, 1994). For a complete description of the methodology and criteria used to select the substances, refer to the final rule (59 FR 4479; January 31, 1994), and proposed modifications (61 FR 16598, April 15, 1996). On August 5, the Chemical Safety Information, Site Security and Fuels Regulatory Relief Act was signed into law (P.L. 106-40). Flammable fuels used as fuel or held for sale as fuel at a retail facility are no longer covered under the RMP program. However, flammable fuels used as a feedstock or held for sale as fuel at a wholesale facilty are still covered.

( CAA Q&A Database, July 1997)

II. 25. Question: Drums containing regulated substances (listed at 40 CFR Section 68.130) are stored in several separate locations at a stationary source and there is no possibility that an accidental release in any of the individual storage areas would impact any of the other storage areas. Must the overall amount of the regulated substance present at the stationary source be considered when determining whether the threshold quantity for that substance is exceeded?

Answer: No. Applicability of the risk management program regulations at 40 CFR Part 68 is contingent upon the existence of more than a threshold quantity of a regulated substance in a process at a stationary source (40 CFR Section 68.10(a)). Although the definition of "process" does include storage, the total amount of a regulated substance in storage at a stationary source does not necessarily constitute a single process. Separate, individual vessels must be considered as a single process for the purpose of threshold determination if both could be released during a single release event, including an event that is external to both vessels (40 CFR Section 68.3). The owner or operator of a stationary source must use his or her best judgment, backed up by a sound technical and scientific basis, to make a determination as to whether two or more vessels may be involved in the same accident, or whether a release from one vessel may reasonably be anticipated to lead to a release from another vessel. The owner or operator should be able to document the decision that the individual vessels do or do not constitute a single process.

( CAA Q&A Database, July 1997)

II. 26. Question: Oleum, which is a mixture of sulfuric acid and sulfur trioxide, is listed as a regulated toxic substance at 40 CFR Section 68.130. Sulfur trioxide is also listed individually as a regulated toxic substance. If a single process consists of one vessel containing oleum and one vessel containing sulfur trioxide, must the amount of sulfur trioxide in the oleum be aggregated with the amount of pure sulfur trioxide in the process when determining whether the threshold quantity for sulfur trioxide is exceeded?

Answer: No. If a process contains discrete amounts of both oleum and sulfur trioxide, the amount of sulfur trioxide that is a part of the oleum mixture should not be considered when determining whether the threshold quantity for sulfur trioxide is exceeded in that process. If the threshold is not met for either chemical, then the process is not subject to part 68, however, the process is subject to Section 112(r)(1), the general duty clause (See questions under General Duty Clause).

( CAA Q&A Database, July 1997)

II. 27. Question: Under 40 CFR Part 68, if multiple processes at a stationary source contain the same regulated substance, must the amounts of the substance in the individual processes be aggregated to determine whether a threshold is exceeded?

Answer: No. Applicability of the risk management program requirements is based upon the presence of more than a threshold quantity of a regulated substance in a process at a stationary source (40 CFR §68.10(a)). The quantity present is evaluated on a process-by-process basis. It is important to note, however, that multiple, separate vessels located such that both could potentially be involved at one time in an accidental release are considered to be a single process (40 CFR §68.3). The owner or operator of a stationary source will need to make a reasonable determination as to whether two or more vessels may be involved in the same accident. The owner or operator should be able to document the decision that the individual vessels do or do not constitute a single process. If the threshold is not met for a process and thus not subject to part 68, the process is still subject to Section 112(r)(1), the general duty clause (See questions under General Duty Clause).

( CAA Q&A Database, July 1997)

II. 28. Question: "Tube" trailers carry bulk liquids that are stacked in a rack type arrangement on the back of a truck trailer. This arrangement often is used to carry highly hazardous materials such as anhydrous hydrogen chloride. The tubes are manifolded together, but usually only one tube at a time is connected to a process for loading and unloading. Are "tube" trailers considered a single process?

Answer: If the "tube" trailers remain in transportation, the contents of the trailers are exempt from threshold determination. If a container [e.g., "tube"] remains attached to the motive power that delivered it to the site, even if a facility accepts delivery, it is in transportation (63 FR 643; January 6, 1998). If the tubes no longer are in transportation, the entire grouping of tubes may be considered a single process if the tubes are interconnected or are co-located such that they could be involved in the same accident.

(CAA Q&A Database, June 1998)

II. 29. Question:  If an owner of a stationary source leases propane tanks from a gas supplier, who is responsible for preparing and submitting the risk management plan (RMP) addressing the propane tanks?

Answer:  The owner of the stationary source is responsible for preparing and submitting the RMP.  The risk management program regulations apply to the owner or operator of a stationary source that has more than a threshold quantity of a regulated substance in a process (40 CFR 68.10(a)).  Regardless of who owns a particular process (in this case, the propane tanks), the owner or operator of the stationary source at which the process is located is responsible for complying with the risk management program regulations (including submission of the RMP) for the process if it contains more than a threshold quantity of a regulated substance.

(CAA Q&A Database, September 1998)

II. 30. Question:  The “owner or operator” of a stationary source with covered processes is required to comply with the risk management program requirements in 40 CFR part 68.  If a stationary source owner leases the source to an operator, who is responsible for submitting the risk management plan (RMP)?

Answer: Both the owner and the operator of a stationary source are responsible for compliance with the risk management program regulations of 40 CFR part 68, including developing and implementing a risk management program and preparing and submitting the RMP.  As a practical matter, the operator may be more likely to have the necessary documentation for the RMP, but both the owner and operator can be held liable for failure to comply with the risk management program regulations.

(CAA Q&A Database, September 1998)

II. 31. Question: My stationary source has a process that contains a maximum of 4,000 lbs. of a regulated substance that has a 5,000 lb. threshold quantity.  When the level of the regulated substance in the process reaches 1,000 lbs., a delivery truck comes on site and connects to the process to replenish the supply.  The tank on the truck holds 10,000 lbs. of the regulated substance.  Must I consider the amount of the regulated substance in the truck’s tank to be a part of my process while the transfer hoses are connected, and therefore complete an RMP for this process?

Answer: No, the regulated substance in the truck’s tank would not be considered part of your process.  A regulated substance in a truck’s tank is considered “in transportation,” and thus not part of a source’s process, as long as the tank is attached to the truck’s motive power (i.e., its cab or engine).  Since in your  case the motive power remains attached to the tank, only the amount of regulated substance your source accepts must be counted towards the threshold quantity.  Since your source will have no more than 4,000 lbs. of a regulated substance even after taking delivery, it will not exceed the threshold quantity for the substance.

(CAA Q & A Database, November 1997)

II. 33. Question: Must the amount of chlorine present in sodium hypochlorite be considered when determining whether a process is subject to the Risk Management Program regulations at 40 CFR part 68?

Answer: No. The risk management program regulations apply only to processes that contain more than a threshold quantity of one of the specifically listed regulated substances in 40 CFR 68.130. Sodium hypochlorite (CAS # 7681-52-9) is not a listed regulated substance. Elemental chlorine (CAS # 7782-50-5) is a regulated substance. If elemental chlorine (or any other regulated substance) is present in a process, the amount of that substance must be considered when determining whether the process is covered. Sodium hypochlorite does not contain elemental chlorine; rather it is a chemical compound comprised of a chlorine ion bonded to an oxygen atom. Therefore, the amount of the chlorine ion present in sodium hypochlorite should not be considered when determining whether a threshold amount of chlorine is present in a process.

(CAA Q & A Database, March 1999)

II. 33. Question: Some landfills vent methane gas generated by the decomposition of waste materials in the landfill to the atmosphere or burn it in a flare while others collect, compress, store, and use it as a fuel. Are landfills subject to the requirements of the RMP program? And, if so, how should the threshold quantity be determined?

Answer: Any facility, including landfills, that handles a regulated substance above the threshold quantity is subject to the RMP requirements. In this case, methane is a listed substance and landfills would have to report if they handle more than 10,000 pounds "in a process." A "process" is defined as "any activity involving a regulated substance including any use, storage, manufacturing, handling or on-site movement of such substances, or combination of these activities." In the case of landfills, methane becomes part of a "process" at the point of collection. Consequently, starting at collection points, the facility would need to determine the quantity of methane contained in the collection, venting, or handling equipment. If the quantity is greater than the threshold quantity (10,000 lbs.), then the process is covered under RMP.

(CAA Q & A Database, March 1999)

II. 34. Question: I operate a single covered process on a site owned by a large company. I manufacture a regulated substance that I pipe to the other company for use in its processes. At what point do the piping and substance become part of the other company’s stationary source?

Answer: The answer will vary. The company that owns and maintains the piping should probably consider it part of its stationary source. If, however, there is a point (e.g., a valve or meter) where the receiving company is considered to take ownership of the substance, then you may decide to divide the piping and its contents at that point.

(CAA Q & A Database, March 1999)

II. 35. Question: The definition of process would seem to indicate that my process is part of the larger company’s process because they are interconnected. Why can’t the larger company just include my process in its RMP?

Answer: Your process is not part of the larger company’s stationary source because it does not meet the statutory criteria for stationary sources. Although the process may be part of the same industrial group and is at the same location, it is not under control of the same person. Therefore, the process is a separate stationary source and must have a separate RMP.

(CAA Q & A Database, March 1999)

II. 36. Question: Formaldehyde is listed in 40 CFR 68.130 with the qualifier “solution.” Does the qualifier refer only to mixtures of formaldehyde and water, or does it apply to any liquid mixture containing formaldehyde?

Answer: Formaldehyde (CAS No. 50-0-0) is listed with the qualifier “solution” because pure formaldehyde has a tendency to polymerize and it is usually handled as an aqueous solution (commercially, 40% formaldehyde, 15% methanol, water). Although the listing refers to aqueous solutions of formaldehyde, other solutions or mixtures may be covered, just as any solution or mixture of any other listed substance. In these cases, the mixture provisions apply; the concentration must be greater than 10 mm Hg to include the amount of listed substance in a threshold quantity determination. Urea-formaldehyde (CAS No. 9011-05-6) is not a formaldehyde solution but a complex polymer molecule. Urea-formaldehyde usually is combined in a reactor to form UF resin. It is shipped to customers as a colloidal aqueous solution with a solid content of about 65%. This liquid is odorless and slightly opaque. When shipped, the UF resin already is polymerized and cross-linked to a certain degree.

(CAA Q & A Database, March 1999)

II. 37. Question: Formaldehyde is not specifically listed with a concentration cutoff, but is listed with the qualifier “solution”. Can the partial pressure exemption be applied to formaldehyde solutions?

Answer: According to 40 CFR 68.115, the amount of any listed toxic substance present in a mixture at a concentration greater than 1% does not need to be included in a threshold quantity determination if it can be shown that the partial vapor pressure is less than 10 mm Hg.

(CAA Q & A Database, March 1999)

II. 38. Question: Are bulk storage terminals exempt from filing a Risk Management Plan?

Answer: There is no general exemption for bulk storage terminals. However, the threshold exemption for “regulated substances in naturally occurring hydrocarbon mixtures prior to entry into a natural gas processing plant or a petroleum refining processing unit” would apply to the regulated substances in the crude oil that meet the other listing criteria for flammable mixtures (i.e. NFPA 4, >1% concentration of listed flammable substance). These substances obviously have undergone processing in a refinery. For non-crude oil substances you need to evaluate on a case-by-case basis whether they trigger the NFPA-4 and >1% criteria. Keep in mind that regulated substances in gasoline, when in distribution of related storage for use as fuel for internal combustion engines, also are exempt from threshold determination.

(CAA Q & A Database, May 1999)

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II. A. 1. Question: Are explosives listed regulated substances under CAA 112(r)?

No.  Explosives classified by the Department of Transportation as Class 1, Division 1.1 were initially listed as regulated substances with a threshold quantity of 5,000 pounds because of their potential to cause offsite impacts (59 FR 4478; January 31, 1994).  In accordance with a Settlement Agreement between EPA and the Institute of Makers of Explosives (IME),  IME
developed and will implement safety practices that will provide additional information and enhance the coordination between explosives facilities and emergency planners and responders.  As discussed in a proposal to Class 1, Div. 1.1 explosives (61 FR 16606, April 15, 1996), EPA concluded that current regulations and current and contemplated industry practices would
promote safety and accident prevention in storage, handling, transportation, and use of explosives.  EPA subsequently issued a final rule delisting Class 1, Division 1.1 explosives (63 FR 640, January 6, 1998).

(CAA Q&A Database, September 1998)

II. A. 2. Question: The amendments to the List Rule (63 FR 640; January 6, 1998) added exemptions from threshold determination for regulated substances in gasoline that is in distribution or related storage for use as fuel for internal combustion engines, and for regulated substances in naturally occurring hydrocarbon mixtures prior to processing.  Do these exemptions apply to regulated toxic substances as well as regulated flammable substances?

No.  The exemption from threshold determination for regulated substances in gasoline or in naturally occurring hydrocarbon mixtures applies only to regulated flammable substances.  These exemptions are codified at 40 CFR Section 68.115 (b)(2), which specifically relates to "concentrations of a regulated flammable substance in a mixture." Any regulated toxic substance
(e.g., hydrogen sulfide) which is present in gasoline or in naturally occurring hydrocarbon mixtures must be considered when determining whether a threshold amount of that substance is present in a process at a stationary source.

(CAA Q&A Database, September 1998)

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II. B. 1. Question: Are there any overall industry exemptions from the Accidental Release Prevention provisions and Risk Management Program regulations?

Answer: The only overall exemption is ammonia used as an agricultural nutrient, when held by farmers. Otherwise owners and operators of stationary sources are subject to §112(r) if any process at the stationary source contains a regulated substance in excess of the applicable threshold quantity (40 CFR §68.10).

(CAA Q&A Database, August 1996)

II. B. 2. Question: Is gasoline exempt from the requirements of 40 CFR Part 68?

Answer:  Although gasoline is not specifically listed as a regulated substance under 40 CFR Section 68.130, it may contain one or more regulated substances. On January 6, 1998 (63 FR 640), EPA exempted from threshold determination regulated flammable substances in gasoline when in distribution or related storage for use as a fuel for internal combustion engines (40 CFR Section 68.115(b)(2)(ii).  For example, if a refinery had a quantity of butane in a storage vessel and a separate quantity of gasoline (containing butane) intended for use as a fuel in an internal combustion engine, only the butane in the storage vessel should be applied toward the 10,000-pound threshold; the quantity of butane in the gasoline used for fuel is exempt.

(CAA Q&A Database, Septebmer 1998)

II. B. 3. Question: Are motor fuels (e.g., gasoline and diesel fuel) exempt from threshold determination?

EPA provided a specific exemption from threshold determination for regulated flammable substances in gasoline used as fuel for internal combustion engines.  This exemption applies solely to gasoline.  However, there is a general exemption from threshold determination for regulated flammable substances in any mixture that does not have an NFPA flammability hazard rating of 4.
This could include other types of motor fuel.  Gasoline was specifically exempted because it does not meet the criteria for an NFPA rating of 4.  Other motor fuels may or may not meet the criteria for an NFPA rating of 4.  Each flammable mixture must analyzed separately.

(CAA Q&A Database, September 1998)

II. B. 4. Question: Under 40 CFR Part 68, for the purpose of determining whether more than a threshold amount of a regulated substance is present at a stationary source, certain exemptions may apply. One such exemption is provided for "activities in laboratories" (40 CFR §68.115(b)(6)). If laboratory chemicals are stored outside the laboratory, are they exempt from threshold determination?

Answer: No. The storage of a regulated substance outside of a laboratory does not qualify for the laboratory use exemption, regardless of whether the substance will eventually be processed or used in the laboratory. When a regulated substance is manufactured, processed, or used in a laboratory at a stationary source under the supervision of a technically qualified individual, the quantity of the substance need not be considered in determining whether a threshold quantity is present. This exemption does not apply to specialty chemical production, pilot plant scale operations, or activities conducted outside the laboratory (40 CFR §68.115(b)(6)).

(CAA Q&A Database, January 1997)

II. B. 5. Question: For the purpose of determining whether more than a threshold amount of a regulated substance is present at a stationary source under 40 CFR Part 68, certain exemptions may apply. One exemption is for regulated substances that are "manufactured, processed, or used in a laboratory at a stationary source under the supervision of a technically qualified individual as defined in §720.3(ee) of this chapter"(40 CFR §68.115(b)(6)). What is the definition of a "technically qualified individual" and what does "§720.3(ee) of this chapter" refer to?

Answer: "§720.3(ee) of this chapter" refers to 40 CFR §720.3(ee) where the regulations under the Toxic Substances Control Act (TSCA) lists definitions. EPA has chosen to adopt this TSCA definition. A technically qualified individual, from this TSCA definition, is "a person or persons (1) who, because of education, training, or experience, or a combination of these factors, is capable of understanding the health and environmental risks associated with the chemical substance which is used under his or her supervision, (2) who is responsible for enforcing appropriate methods of conducting scientific experimentation, analysis, or chemical research to minimize such risks, and (3) who is responsible for the safety assessments and clearances related to the procurement, storage, use, and disposal of the chemical substance as may be appropriate or required within the scope of conducting a research and development activity."

(CAA Q&A Database, May 1997)

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II. C. 1. Question: Why have transportation activities been exempted from compliance with the risk management program regulations at 40 CFR Part 68? Why do these regulations apply only to stationary sources?

Answer: While EPA agrees that industry, local planners, and first responders need to recognize the public safety hazards associated with transportation, the Clean Air Act directs EPA to focus on stationary sources. Transportation-related chemical safety is the responsibility of the Department of Transportation.

(CAA Q&A Database, October 1996)

II. C. 2. Question:The definition of stationary source does not apply to transportation, including storage incident to transportation (40 CFR Section 68.3). Are chemicals in a tank car (e.g., tanker truck or rail car) therefore exempt from threshold determination?

Answer: The chemicals in the tank car are exempt only if the tank car is in transportation. EPA considers a container to be in transportation as long as it is attached to the motive power (e.g., truck or locomotive) that delivered it to the site (63 FR 643, January 6, 1998). If the tank car is detached from the motive power, and therefore no longer in transportation, the contents of the tank car must be considered in the threshold determination.

(CAA Q&A Database, Septebmer 1998)

II. C. 3. Question: Would the risk management program regulations cover the loading and unloading of transportation containers?

Answer: The definition of stationary source includes transportation containers used for storage not incident to transportation and transportation containers connected to equipment at a stationary source for loading or unloading (40 CFR Section 68.3). In a January 6, 1998 final rule (63 FR 640), EPA clarified that if a container remains attached to the motive power that delivered it to the site, even if a facility accepts delivery, it would be in transportation, and the contents would not be subject to threshold determination (63 FR 643).

(CAA Q&A Database, September 1998)

II. C. 4. Question: How did the January 6, 1998, final rule (63 FR 640) affect the definition of stationary source, as it relates to the transportation exemption?

Answer: The January 6, 1998 final rule amended the regulatory definition of stationary source by removing previous references to “active shipping papers” and “temporary storage” and by clarifying that transportation includes, but is not limited to, transportation in pipelines 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 the Department of Transportation under 49 U.S.C. 60105 (40 CFR Section 68.3). Preamble language in the same rule further clarifies when a container is considered to be in transportation. A container is in transportation and excluded from the definition of stationary source, when it is attached to the motive power (e.g., a truck or locomotive) that delivered it to the site (63 FR 643; January 6, 1998). Conversely, a container detached from the motive power that delivered it to the site is included as a part of the stationary source.

(CAA Q&A Database, September 1998)

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III. 1. Question: The preamble of the Risk Management Program final rule (61 FR 31670) states that Program 3 applies to processes in certain SIC codes. It also states that Program 3 applies to any process subject to the OSHA Process Safety Management (PSM) standard, unless the process is eligible for Program 1. If a process meets the requirements of Program 1, but is also in SIC code 2611 (one of those identified for Program 3 applicability), is that process subject to the Program 1 or Program 3 requirements?

Answer: The Program 1 eligibility criteria are found at 40 CFR §68.10(b). If a process meets the criteria for Program 1, that process is subject only to the Program 1 requirements, regardless of the applicable SIC code or whether the process is subject to OSHA's PSM. Program 3 requirements do not apply to processes which meet the Program 1 eligibility criteria (40 CFR §68.10(d)).

(CAA Q&A Database, August 1996)

III. 2. Question: If a stationary source has several processes that are covered under 40 CFR Part 68, and some of those processes have had an accidental release within the past five years (effectively making those processes ineligible for Program 1 status), are the individual processes from which no accidents have occurred also ineligible for Program 1 status?

Answer: No. Eligibility determinations for Program 1 status are made separately for each process. If any individual process meets all of the criteria listed at 40 CFR §68.10(b), that process is eligible for Program 1 status.

(CAA Q&A Database, October 1996)

III. 3. Question: A process covered under 40 CFR Part 68 is eligible for Program 1 requirements if it meets all of the criteria listed at 40 CFR §68.10(b). Those criteria include a requirement that the process cannot have had an accidental release of a regulated substance that led to offsite death, injury, or environmental response or restoration activities within five years prior to the risk management plan (RMP) submission. If there is an accident that results in serious offsite consequences from a previously identified and documented Program 1 process, when will the process lose its Program 1 status? Must the RMP be revised to reflect the change in status and requirements for that process?

Answer: The process in this scenario will lose its Program 1 status immediately, and the owner or operator will have to comply with the requirements of the new program level applicable to the process (40 CFR §68.10(e)). The owner or operator will be required to revise and update the RMP to reflect that change within six months of the incident (40 CFR §68.190(b)(7)).

(CAA Q&A Database, January 1997)

III. 4. Question: The eligibility criteria for Program 1 status under 40 CFR Part 68 include a requirement that the process must not have had an accidental release resulting in serious offsite consequences for the past five years (40 CFR 68.10(b)(1)). Can a newly-constructed process that has no accident history qualify for Program 1 status?

Answer: Yes. A covered process is eligible for Program provided:

(1) the process has not had an accidental release of a regulated substance that resulted in off-site death, injury, or response or restoration activities at an environmental receptor in the five years prior to the submission date of the RMP;
(2) there are no public receptors within the distance to a toxic or flammable endpoint associated with a worst-case release scenario; and
(3) emergency response procedures have been coordinated with the local emergency planning committee and response organizations (40 CFR 68.10).

The emergency response plan must include the name and phone number of the coordinating agency. A facility’s emergency response plan must be coordinated with the community emergency response plan under EPCRA for the facility’s community (40 CFR 68.95). The LEPC for the facility’s community typically will be the agency with which the emergency response plans are coordinated.

If your facility does not have an emergency response plan, indicate the agency that you have coordinated your response activities with. If you have regulated toxic substances and your employees will not be responding to accidental releases, your facility must be included in the community emergency response plan developed by the LEPC. If that is the case, indicate the name and phone number of your LEPC on the RMP. If you only have regulated flammable substances and your employees will not be responding to releases of those substances, you must have coordinated response actions with the local fire department. If that is the case, indicate the name and phone number of your local fire department on your RMP.

(CAA Q&A Database, March 1999)

III. 5. Question: If a stationary source comprises some covered processes that meet the eligibility requirements for one of the three programs (i.e., Program 1, 2, or 3) and some processes that are subject to a different program, must the owner or operator of the source submit multiple risk management plans (RMPs)?

Answer: No. Although a stationary source may have processes in one or more of the three programs (61 FR 31670; June 20, 1996), the owner or operator must submit a single RMP that includes the information required by 40 CFR §§68.155 through 68.185 for all covered processes at that source (40 CFR §68.150(a)). That RMP will contain relevant information on each covered process.

(CAA Q&A Database, January 1997)

III. 6. Question: A covered process that is ineligible for Program 1 will be subject to Program 3 requirements if the process is in one of nine specified standard industrial classification (SIC) codes, or is subject to the OSHA Process Safety Management (PSM) standard (40 CFR Part 68.10(d)). When determining Program 3 applicability for a particular process, should the owner or operator use the primary SIC code that describes the stationary source's main business?

Answer: No. The owner or operator must determine the individual SIC code for each covered process to determine whether Program 3 applies (61 FR 31670; 6/20/96). The assigned SIC code should reflect the activity of the process, and will not necessarily be the same as the source's overall primary SIC code.

(CAA Q&A Database, January 1997)

III. 7. Question: If five years have passed since the last accident involving a covered process, and that process meets the other two requirements identified under 40 CFR §68.10(b) for Program 1 eligibility, could that process become a Program 1 process even if it had previously been identified as a Program 2 or 3 process?

Answer: Yes. The status of a particular process can change over time. Any process that meets all of the criteria listed at 40 CFR §68.10(b) is eligible for Program 1 status, regardless of the prior status of that process. If the owner or operator chooses to change Program levels, he must file an updated RMP to reflect this change in program level within six months of becoming eligible for Program 1 (See 40 CFR §68.190(b)(7)).

(CAA Q&A Database, May 1997)

III. 8. Question: The risk management program regulations in 40 CFR Part 68 are applicable to owners or operators of stationary sources at which more than a threshold quantity of a regulated substance is present in a process (40 CFR Section 68.10(a)). Are all covered processes subject to identical risk management program requirements?

Answer: No. To ensure that individual processes are subject to requirements commensurate with their size and process type, EPA has classified them into three categories, or "programs." Program 3 processes are subject to the most comprehensive requirements and comprise relatively complex chemical processing operations in specified Standard Industrial Classification (SIC) codes and processes already subject to the OSHA process safety management (PSM) standard. Program 2 processes are subject to a streamlined version of the requirements, and include generally less complex operations that do not involve chemical processing. Program 1 processes, subject to minimal requirements, are those from which a worst-case release would not affect the public. Further, since the RMP rule requirements are performance based, owners or operators of stationary sources with processes in Programs 2 or 3 have flexibility under the rule to tailor their programs to best meet their own risk management needs.

( CAA Q&A Database, July 1997)

III. 9. Question: A facility performed a worst-case release scenario and determined that there are no public receptors within the endpoints. There are several residences located just outside the endpoint. In reviewing the five year accident history, there were several releases of a regulated substance, in which the residences were notified by the facility of the releases and informed they should shelter-in-place. Do these releases disqualify the facility from being a Program 1 facility?

Answer: No, these releases do not disqualify the facility from Program 1 eligibility. Evacuations and sheltering-in-place were not included in the eligibility for Program 1 because EPA was concerned that they could create a disincentive to report releases and might encourage sources and local emergency officials to take more chances during an event when there may be potential exposures that do not rise to the endpoint specified in this rule but would otherwise be worthy of precautionary actions by the source or by local officials.

If local emergency planners, first responders or the public have concerns about processes in Program 1 because of a past evacuation or sheltering-in-place event, then mechanisms under EPCRA could be used to gather more information from the source about its prevention program (such as EPCRA sections 302(b)(2) [designation of a facility if it does not already handle extremely hazardous substances listed under section 302] and 303(d)(3) [provision of information to the emergency planning committee]) and involve the source in emergency planning. Sources and local first responders should be discussing evacuation and sheltering-in-place criteria and decisions as part of emergency response planning (61 FR 31675-6; June 20, 1996).

( CAA Q&A Database, July 1997)

III. 10. Question: My process includes a series of interconnected units, as well as several storage vessels that are co-located. Several sections of the process could qualify for Program 1. Can I divide my process into sections for the purpose of assigning Program levels?

Answer: No, you cannot subdivide a process for this purpose. The highest Program level that applies to any section of the process is the Program level for the whole process. If the entire process is not eligible for Program 1, then the entire process must be assigned to Program 2 or Program 3.

(CAA Q & A Database, March 1999)

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IV. A. 1. Question: Under the hazard assessment requirements of 40 CFR Part 68, Subpart B, an owner or operator must analyze worst-case release scenarios and more likely alternative release scenarios, and must document a five-year accident history. If a regulated substance exhibits characteristics of both toxicity and flammability, should owners and operators consider both impacts when performing the hazard assessment?

Answer: No. Owners and operators are only required to analyze a regulated substance for the hazard for which it is listed. For example, ammonia is listed as a regulated toxic substance, thus the worst-case release scenario must be modeled as a toxic release. However, to make the public and first responders aware of additional hazards, an owner or operator may want to consider the impact associated with an explosion or fire involving a listed toxic substance. As part of the Program 2 hazard review (40 CFR §68.50) and Program 3 process hazard analysis (40 CFR §68.67), however, all hazards of a regulated substance should be considered.

(CAA Q&A Database, January 1997)

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IV. B. 1. Question: The preamble to the Risk Management Program Rule (61 FR 31668; June 20, 1996) states that "one worst-case release scenario will be defined to represent all toxics, and one worst-case release scenario will be defined to represent all flammables held above the threshold at the source" (61 FR 31671). The preamble language further specifies that owners and operators of stationary sources need only "report one worst-case release scenario for all flammables and one worst-case release scenario for all toxics at the source" (61 FR 31683). These general discussions do not address any differences among Program 1, 2, and 3 requirements. Are the worst-case release analysis requirements for Program 1 processes different than those for Program 2 and 3 processes? Must a worst-case release scenario analysis be completed and reported for each Program 1 process?

Answer: Yes. The regulations at 40 CFR §68.25(a)(1) state that one worst-case release scenario must be analyzed and reported in the risk management plan for each Program 1 process. In order for any process to be eligible for Program 1 requirements, it must be demonstrated that a worst-case release from that process would not affect any public receptor (40 CFR §68.10(b)(2)). For Program 2 and 3 processes, a single worst-case release scenario analysis may be reported to represent all regulated toxic substances, and a single worst-case release scenario analysis will be acceptable to represent all regulated flammable substances. Additional worst-case release scenarios must, however, be analyzed and reported for Program 2 and 3 processes if worst-case releases from other covered processes potentially affect public receptors different from those affected by the first worst-case release scenario (40 CFR §68.25(a)(2)).

(CAA Q&A Database, September 6, 1996)

IV. B. 2. Question: The owner or operator of a stationary source covered by the risk management program regulations must conduct a worst-case release scenario analysis as part of the required hazard assessment (40 CFR §68.25). The worst-case release is defined 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 an endpoint (40 CFR §68.3). If a release from the process containing the largest quantity of a regulated substance would result in a shorter distance to an endpoint than a release from a smaller process, which scenario should be considered the worst-case release?

Answer: The worst-case release is the scenario that results in the greatest distance to an endpoint beyond the stationary source boundary (40 CFR §68.25(h)). EPA recognizes that there could be release scenarios in which a smaller process could generate a greater distance to an endpoint than a release from the largest vessel or pipeline (61 FR 31682; June 20, 1996). The regulatory language at 40 CFR §68.25(h) clarifies that a scenario involving a smaller quantity of regulated substance handled at a higher process temperature or pressure, as well as a scenario involving a smaller quantity located closer to the stationary source boundary may, in fact, result in the worst-case release.

(CAA Q&A Database, October 1996)

IV. B. 3. Question: The owner or operator of a stationary source subject to the risk management program regulations must analyze the worst-case release scenario involving a Program 2 or 3 process containing a regulated flammable substance and the worst-case release scenario involving a Program 2 or 3 process containing a regulated toxic substance (40 CFR §68.25). If the worst-case release scenarios for a regulated toxic substance and for a regulated flammable substance involve the same process, must both scenarios be analyzed?

Answer: Yes. If the worst-case release scenarios for a regulated toxic substance and for a regulated flammable substance in Program 2 and 3 processes are associated with the same process, the two worst-case release scenarios must be analyzed separately.

(CAA Q&A Database, October 1996)

IV. B. 4. Question: A stationary source subject to the risk management program regulations at 40 CFR Part 68 comprises multiple Program 2 and Program 3 covered processes. The owner or operator must do a single worst-case release analysis to represent toxic regulated substances and a single worst-case release analysis to represent flammable regulated substances (40 CFR §68.25(a)(2)). Could the worst-case scenario for a toxic substance involve a Program 2 process while the worst-case scenario for a flammable substance involves a Program 3 process, and vice versa?

Answer: Yes. For the purpose of the hazard assessment requirements of 40 CFR Part 68, Subpart B, no distinction is made between Program 2 and Program 3 processes. The worst-case release scenario for toxic substances can be represented by either a Program 2 or a Program 3 process, and the worst-case release scenario for flammable substances can also be represented by either a Program 2 or a Program 3 process.

(CAA Q&A Database, October 1996)

IV. B. 5. Question: Performance of the hazard assessment required under 40 CFR Part 68, Subpart B, includes analysis of both worst-case release scenarios (40 CFR §68.25) and alternative release scenarios (40 CFR §68.28). In each of these analyses, passive mitigation systems may be taken into consideration. If a tank has a "double wall," does that qualify as "passive mitigation"?

Answer: No. Passive mitigation is defined at 40 CFR §68.3 as "equipment, devices, or technologies that function without human, mechanical, or other energy input." Passive mitigation systems include building enclosures, dikes, and containment walls (61 FR 31683; June 20, 1996), but a double wall of a tank is not considered to be passive mitigation. In general, passive mitigation serves to minimize potential adverse effects after the loss of containment, whereas a precaution such as a double wall of a tank serves to prevent the loss of containment in the first place.

(CAA Q&A Database, January 1997)

IV. B. 6. Question: A refinery uses a special proprietary additive to their hydrofluoric acid (HF) alkylation process. This HF additive has shown in tests to significantly reduce aerosol forms of HF during accidental releases, and therefore reduce the distance traveled by HF releases. The additive is present at all times during the alkylation process. Can the refinery claim that this HF additive is a passive mitigation technique and use it as such in their development of their worst-case scenario numbers?

Answer: Passive mitigation systems are defined as those systems that operate without human, mechanical, or other energy input and would include building enclosures, dikes, and containment walls. In this case, the HF additive would not actually be considered passive mitigation; rather, the presence of the additive could be better reflected in the worst case and alternative release scenarios. The owner or operator could show that with the HF additive, the HF that they have on site is not a pure substance (toxic mixture criteria would apply) and in the event of an accidental release, the HF does not behave as a pure material, and the dispersion results reflect this difference. The owner or operator could highlight these differences and demonstrate how the process may be safer as a result. EPA recognizes and encourages prevention through these and other passive or inherently safer process techniques.

(CAA Q&A Database, January 1997)

IV. B. 7. Question: When selecting the worst-case release scenario for Program 2 and 3 processes as required by 40 CFR §68.25, a stationary source owner or operator must analyze the release scenario that results in the greatest distance to an endpoint. Does the "greatest distance to an endpoint" refer to the greatest total distance from the process (e.g., vessel or pipeline), or to the distance beyond the stationary source boundary?

Answer: The greatest distance to an endpoint will ultimately refer to the distance beyond the stationary source boundary. When selecting a worst-case release scenario, the stationary source owner or operator must first evaluate potential releases from all Program 2 and 3 covered processes. Each release is modeled as a circle, with its center at the process and with a radius equaling the distance to the endpoint concentration (Response to Comments document, Ch. 5, pg. 5-109). The owner or operator must then choose the scenario that results in the greatest distance to an endpoint (40 CFR 68.25(a)(2)). If a scenario with a smaller overall distance to an endpoint, however, could result in a greater distance to an endpoint beyond the stationary source boundary (e.g., the process is very close to the facility boundary), it must be chosen as the worst-case release scenario (40 CFR §68.25(h)).

(CAA Q&A Database, January 1997)

IV. B. 8. Question: Under the risk management program regulations at 40 CFR Part 68, if a Program 1 process contains a threshold amount of both a regulated toxic substance and a regulated flammable substance, should a worst case release scenario be analyzed for each of the substances in the process?

Answer: Yes, a worst case release scenario must be analyzed for each regulated toxic and flammable substance above the threshold. This analysis will serve two purposes: 1) to demonstrate that no release from that process would reach a public receptor as required in 40 CFR §68.10(b)(2); and 2) to determine the one "worst" worst case release scenario that results in the greatest distance to an endpoint, which must be reported in the RMP.

(CAA Q&A Database, May 1997)

IV. B. 9. Question: As a part of the hazard assessment requirements under 40 CFR Part 68, Subpart B, I must analyze worst-case release scenarios and document certain analyses in my risk management plan (RMP). How many worst-case release scenarios must be analyzed, and how many analyses must be specifically documented in the RMP?

Answer: In order to accurately determine which worst-case release scenarios should be specifically documented in the RMP, the owner or operator may need to analyze the worst-case release scenario (i.e., determine the scenario with the greatest distance to an endpoint) for every covered process. If any particular covered process contains more than one regulated substance in excess of a threshold quantity, worst-case release scenarios involving each of those substances may need to be analyzed.

In order for any process to be eligible for Program 1 requirements, the owner or operator must demonstrate that the worst-case release from that process will not affect any public receptor (40 CFR §68.10(b)(2)). A worst-case release scenario analysis must therefore be reported in the RMP for each Program 1 process (40 CFR §68.25(a)(1)). If a Program 1 process contains more than one regulated substance in excess of the appropriate threshold quantity, the documented analysis should be for the release scenario involving the substance that would result in the greatest distance to an endpoint.

For Program 2 and 3 processes, a single worst-case release scenario analysis may be documented to represent the worst of all scenarios (i.e., the scenario resulting in the greatest distance to an endpoint) from covered processes containing regulated toxic substances, and a single worst-case release scenario analysis may be documented to represent the worst of all scenarios involving regulated flammable substances. Additional worst-case release scenarios must, however, be analyzed and reported for Program 2 and 3 processes if worst-case releases from other covered processes potentially affect public receptors different from those affected by the "worst" worst-case release scenarios (40 CFR §68.25(a)(2)(iii)).

(CAA Q&A Database, May 1997)

IV. B. 10. Question: For the purpose of analyzing the worst-case release scenario required as part of the hazard assessment at 40 CFR Part 68, Subpart B, the worst-case release quantity is identified as the greatest amount held in a single vessel or pipe, taking into account administrative controls that limit the maximum quantity (40 CFR 68.25(b)). Why did EPA choose to allow consideration of administrative controls when determining the worst-case release quantity?

Answer: EPA's decision to allow administrative controls to be considered when determining the worst-case release quantity was based on the historical reliability of such controls and the role that such a provision could play in encouraging their further use. This approach acknowledges the efforts by sources to increase process safety by intentionally reducing the inventory of regulated substances (e.g., vessels kept at half capacity to allow for process upsets, emergency shutdowns, and deinventorying or maintenance turnarounds) (61 FR 31682; June 20, 1996). Since the worst case scenario assessment implies that this kind of an event could occur at any time, the scenario must account for the maximum amount contained at any one time, including amounts potentially added to the vessel inventory during an emergency or shutdown.

( CAA Q&A Database, July 1997)

IV. B. 11. Question: When analyzing the worst-case release scenario for a process containing a regulated toxic substance, must an owner or operator anticipate a specific cause (e.g., fire, explosion, etc.) of the selected worst-case release scenario?

Answer: No. The worst-case release scenario analyses for releases of regulated toxic substances must conform to specific assumptions as identified at 40 CFR 68.25(c) and (d). For example, a vessel or pipe containing a regulated toxic substance that is normally a gas at ambient temperature and is handled as a gas or as a liquid under pressure must be assumed to release its entire contents over a ten-minute period for gases or instantaneously for liquids in a worst-case release scenario (40 CFR 68.25(c)(1)). Anticipated causes of the release will not affect the analysis, and are not required. However, a specific cause may be considered as part of the alternative release scenario although it is not a requirement.

( CAA Q&A Database, July 1997)

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IV. C. 1. Question: As part of the hazard assessment, owners and operators of Program 2 and Program 3 covered processes must identify and analyze alternative release scenarios (40 CFR §68.28). What criteria should be used when selecting an alternative release scenario?

Answer: The owner or operator of a stationary source subject to the risk management program regulations at 40 CFR Part 68 must analyze one alternative release scenario to represent all flammables in a covered process and one alternative release scenario for each toxic in a covered process. The owner or operator must chose a scenario that is more likely to occur than the worst-case release scenario and that will reach an endpoint off site (40 CFR §68.28 (b)). Even if no alternative release scenario reaches an off-site endpoint, the source is still required to perform an alternative release scenario that is more likely to occur than the worst-case scenario. When selecting an alternative release scenario, the source shall consider releases that have been documented in the five-year accident history, or failure scenarios identified through the process hazard analysis or hazard review (40 CFR §68.28). Sources should consider several types of events listed under 40 CFR §68.28(b)(2), where applicable.

(CAA Q&A Database, May 1997)

IV. C. 2. Question: I run a wastewater treatment plant that is subject to the risk management program regulations under 40 CFR Part 68 for a covered process containing chlorine. A chlorine scrubber system at the plant is designed to prevent any possible releases from reaching a toxic endpoint offsite. How does this active mitigation system affect my selection and analysis of an alternative release scenario?

Answer: Although only passive mitigation systems (not active) may be considered in the analysis of the worst-case release scenario (40 CFR §68.25(g)), an active mitigation systems (e.g., chlorine scrubbers), also may be considered in the analysis of alternative release scenarios as long as the system is capable of withstanding the event that triggered the release and would still be functional (40 CFR §68.28(d)). When selecting the alternative release scenario, the owner or operator must consider the five-year accident history and failure scenarios identified in the hazard review or process hazard analysis (40 CFR §68.28(e)). Additionally, the owner or operator must select an alternative release scenario that is more likely to occur than the worst-case scenario, and that will reach an endpoint offsite, unless no such scenario exists (40 CFR §68.28(d)). If consideration of active mitigation systems at the stationary source results in no release scenarios that reach an endpoint offsite, then the owner or operator still must analyze and document an alternative release scenario, even if its endpoint will be reached within the boundaries of the facility.

(CAA Q&A Database, June 1998)
 
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IV. D. 1. Question: An endpoint is needed for analysis of offsite consequences of potential accidental releases of regulated substances. The endpoint to be used for each regulated toxic substance is provided in Part 68, Appendix A, and is the Emergency Response Planning Guideline level 2 (ERPG-2) developed for the substance by the American Industrial Hygiene Association, unless an ERPG-2 has not been developed for the substance. Why were ERPG-2 values selected instead of ERPG-3?

Answer: EPA based its decision to utilize ERPG-2 values as the toxic endpoints for offsite consequence analyses on comments received from the public and the regulated community. The Agency's focus was on exposure resulting in serious, irreversible health effects, which is best represented by the ERPG-2 values. ERPG-3 values, which represent lethal exposure levels, were rejected on the basis that they are not protective enough of the public in emergency situations. For toxic substances which have no ERPG-2 values, the endpoint to be used is the level of concern (LOC), as identified in the Technical Guidance for Hazards Analysis (December 1987), updated where necessary to reflect new toxicity data (61 FR 31672; June 20, 1996). LOCs are intended to be protective of the general public for exposure periods of up to an hour. These levels have been peer reviewed by EPA's Science Advisory Board, and are widely accepted by the emergency response planning community.

(CAA Q&A Database, September 6, 1996)

IV. D. 2. Question: When evaluating the worst-case release scenario for spills of liquid toxic substances, the owner or operator should assume that the maximum quantity within the vessel or pipe was released instantaneously to form a liquid pool (40 CFR §68.25(d)(1)). For regulated toxic substances that are normally gases at ambient temperature, the worst-case release is assumed to occur over a ten minute period (40 CFR §68.25(c)(1)). For regulated toxic gases that are liquefied by refrigeration, should the worst-case release be evaluated as a liquid or gas release?

Answer: The worst-case release scenario for gases handled as refrigerated liquids at ambient pressure may be evaluated as either a liquid or a gas, depending on containment. If the released substance is not contained by passive mitigation systems or if the contained liquid pool formed would have a depth of one centimeter or less, the owner or operator must assume that the substance is released as a gas in 10 minutes (40 CFR §68.25(c)(2)(i)). If the released substance is contained by passive mitigation systems and forms a liquid pool with a depth greater than one centimeter, the substance may be evaluated as a liquid and assumed to form an instantaneous pool (40 CFR §68.25(c)(2)(ii)).

(CAA Q&A Database, October 1996)

IV. D. 3. Question: What atmospheric conditions must a source assume when performing the offsite consequence analyses required under 40 CFR Part 68, Subpart B?

Answer: For the worst-case release analysis, 1.5 meters per second wind speed and F atmospheric stability class must be assumed, unless the stationary source owner or operator can demonstrate that local meteorological data applicable to the stationary source show a higher minimum wind speed or less stable atmosphere at all times during the previous three years (40 CFR §68.22(b)). For releases of regulated toxic substances, the owner or operator must also use the highest daily maximum temperature and the average humidity for the site during the past three years. Owners and operators using the RMP Offsite Consequence Analysis Guidance will assume 25 degrees Celsius and 50 percent humidity (40 CFR §68.22(c)).

For the alternative release scenario, the owner or operator should use the typical meteorological conditions (i.e., wind speed and atmospheric stability) for the stationary source (40 CFR §68.22(b)), as well as typical temperature and humidity data gathered at the stationary source or at a local meteorological station (40 CFR §68.22(c)). Owners and operators using the

RMP Offsite Consequence Analysis Guidance will assume 3 meters per second wind speed, D atmospheric stability class, 25 degrees Celsius and 50 percent humidity.

(CAA Q&A Database, January 1997)

IV. D. 4. Question: For the purpose of the offsite consequence analyses required under

40 CFR Part 68, Subpart B, there are several instances in which data gathered at a local meteorological station may be used to establish the modeling parameters of wind speed, atmospheric stability, temperature, and humidity for the stationary source. How close must a stationary source be to a weather station in order for that station's data to be applicable to the stationary source?

Answer: EPA has not set specific distance limits, but will allow owners and operators to use their best judgement to determine if the data from a weather station should reasonably apply to the stationary source. Factors such as topography and distance between the stationary source and a weather station should be taken into consideration when evaluating the applicability of the weather station's data to the stationary source.

(CAA Q&A Database, May 1997)

IV. D. 5. Question: Must air dispersion models that are used to analyze worst-case release scenarios under 40 CFR Section 68.25 be able to account for multiple vessels and how those vessels could impact one another in the event of an accidental release?

Answer: No. Models used for worst-case release scenario analysis do not need to consider compounding effects of accidental releases from multiple vessels because the worst-case release is based on a single vessel or process line failure that will result in the greatest distance to an endpoint (40 CFR §68.3).

( CAA Q&A Database, July 1997)

IV. D. 6. Question: Under the hazard assessment requirements of 40 CFR Part 68, Subpart B, an owner or operator is required to analyze a worst-case release scenario and more likely alternative release scenarios. Has EPA developed any air dispersion models for conducting these evaluations? Is EPA's TScreen model an appropriate technique?

Answer: EPA has developed the RMP Offsite Consequence Analysis Guidance document which provides technical guidance and reference tables for worst-case and alternative release scenario assessments. Stationary source owners and operators may, however, use any generally recognized, commercially or publicly available air dispersion modeling techniques, provided the modeling parameters specified in the rule are used (61 FR 31672; June 20, 1996).

EPA's Office of Air Quality Planning and Standards has prepared a publicly available modeling tool called TScreen that can assist owners and operators with consequence assessments (61 FR 31684; June 20, 1996). TScreen can be used to simulate a release and to calculate the dispersion characteristics and pollutant concentrations of the resulting plume. TScreen can be downloaded from EPA's Technology Transfer Network Bulletin Board System. EPA has also developed an emergency response model called Areal Locations of Hazardous Atmospheres (ALOHA). ALOHA can be used to plot the area downwind of a release where concentrations may exceed a user-set threshold level. ALOHA is available from the National Safety Council. (Offsite Consequence Analysis Guidance, Exhibit A-1)

( CAA Q&A Database, July 1997)

IV. D. 7. Question:  I am working on the alternative release scenario portion of my Risk Management Plan (RMP), as required by 40 CFR Section 68.28.  Specifically, I am trying to calculate my release rate and release quantity values.  The final rule does not specify exactly how to calculate these values for the alternative release scenario, as it does for the worst case release scenario.  The Offsite Consequence Analysis Guidance describes fluid flow calculation methods and other referenceable methodologies.  Would these calculation methods be acceptable for determining my alternative release scenario release rate and release
quantities?

Answer: Yes, sources can use the OCA guidance methodology or any other technically sound method to
calculate Alternative Release Scenarios.

(CAA Q & A Database, November 1998)

IV. D. 8. Question: I am trying to complete my worst case release scenario for the Risk Management Plan under §68.25.  I understand that I am required to use a wind speed of 1.5 m/s and F atmospheric stability class as specified in §68.22(b), unless I can prove that at no time over the previous three years were the atmospheric conditions at my stationary source characteristic of the F atmospheric stability class.  Can I use the most readily available meteorological data for any three years prior to
the submission of the RMP?

Answer: No.  You must use the meteorological data for the three most recent years prior to the submission of your RMP for a covered process.  Therefore, if you submit your RMP for a covered process in 1999, the “previous three years” that you must use for your meteorological data will be 1996, 1997, and 1998.

(CAA Q & A Database, November 1998)

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IV. E. 1. Question: A process covered under 40 CFR Part 68 is eligible for Program 1 requirements if it meets all of the criteria listed at 40 CFR §68.10(b). One of those criteria is that the distance to a toxic or flammable endpoint for a worst-case release assessment is less than the distance to any public receptor. Are roads covered as "public receptors"?

Answer: No. Public receptor is defined at 40 CFR §68.3 to include "offsite residences, institutions (e.g., schools, hospitals), industrial, commercial, and office buildings, parks, or recreational areas inhabited or occupied by the public at any time without restriction by the stationary source where members of the public could be exposed to toxic concentrations, radiant heat, or overpressure, as a result of an accidental release." Roads are not included as public receptors. Another criterion for Program 1 eligibility, however, is the requirement that emergency response procedures have been coordinated between the stationary source and local emergency planning and response organizations (40 CFR §68.10(b(3)). Although roads surrounding a stationary source need not be addressed as public receptors, they should be considered when coordinating with emergency planners and responders.

(CAA Q&A Database, January 1997)

IV. E. 2. Question: As part of the hazard assessment under 40 CFR Part 68, Subpart B, a source is required to estimate in its risk management plan (RMP) the population within a circle that has its center at the process and its radius equal to the distance to the endpoint concentration (40 CFR §68.30). If the estimated population changes, would the RMP have to be updated?

Answer: No. Changes in U.S. Census data do not necessitate the revision of the RMP. However, all updates to the RMP should utilize the most recent U.S. Census data.

(CAA Q&A Database, January 1997)

IV. E. 3. Question: When analyzing off-site consequences for the purpose of a worst-case or alternative release scenario under the risk management program regulations (40 CFR Part 68), are areas occupied solely by employees at the source considered to be public receptors?

Answer: No. Such areas at the stationary source are not to be included as public receptors.

(CAA Q&A Database, May 1997)

IV. E. 4. Question: A process covered under 40 CFR Part 68 is eligible for Program 1 requirements if it meets all of the criteria listed at 40 CFR §68.10(b). One of those criteria is that the distance to a toxic or flammable endpoint for a worst-case release assessment is less than the distance to any public receptor. If a stationary source has a baseball field on site to which non-employees have unrestricted access, does that field constitute a "public receptor"?

Answer: Public receptor is defined at 40 CFR §68.3 to include "offsite residences, institutions (e.g., schools, hospitals), industrial, commercial, and office buildings, parks, or recreational areas inhabited or occupied by the public at any time without restriction by the stationary source where members of the public could be exposed to toxic concentrations, radiant heat, or overpressure, as a result of an accidental release." Areas within a facility boundary are considered "offsite" if the public has routine and unrestricted access during or outside normal business hours (40 CFR 68.3). A baseball field to which the public has unrestricted access is therefore considered to be a public receptor if people using the field could be exposed to toxic concentrations, radiant heat, or overpressure as a result of an accidental release.

( CAA Q&A Database, July 1997)

IV. E. 5. Question:  Are barracks and family housing units located on military bases considered public receptors?

Answer:Barracks are not considered public receptors, family housing unit are. Public receptors include any "offsite residences ... inhabited or occupied by the public at any time without restriction by the stationary source where members of the public could be exposed to toxic concentrations, radiant heat, or overpressure, as a result of an accidental release” (40 CFR 68.3). “Offsite” means “areas beyond the property boundary of the stationary source, and areas within the property boundary to which the public has routine and unrestricted access during or outside business hours” (40 CFR 68.3). “Public” means “any person except employees or contractors at the stationary source” (40 CFR 68.3).

Even when family housing units are located within the property boundary of a military base, they are considered public receptors.

Family housing units are, by definition, residences occupied by the “public,” since at least some family members will not be employees of the military. They are also “offsite” because the “public” has routine and unrestricted access to them.

By contrast, barracks on a military base are not public receptors since they are intended only for the use of military personnel.

(CAA Q&A Database, Septebmer 1998)

IV. E. 6. Question: The definition of public receptor is "offsite residences, institutions (e.g., schools, hospitals), industrial, commercial, and office buildings, parks, or recreational areas inhabited or occupied by the public at any time without restriction by the stationary source ..." Offsite is further defined to include "areas within the property boundary [of the stationary source] to which the public has routine and unrestricted access..."(40 CFR §68.3). If a company has a property boundary with no fence, but with many "no trespassing" signs, would the “no trespassing” signs be enough to justify restricted access, and thus make the area inside the signs considered onsite?

Answer: In most cases "no trespassing” signs will not be enough to consider the area inside the signs on- site. Generally, to be considered onsite, access should be physically restricted (e.g., the site is fenced, and security guards are on duty or badges are needed to gain entry). However, every facility must look at its own situation and make a reasonable determination as to whether access is really restricted. The facility should document its decision.

(CAA Q & A Database, November 1998)

IV. E. 7. Question: My processes are fenced, but my offices and parking lot for customers are unrestricted. What is considered offsite? What is considered a public receptor?

Answer: The unrestricted areas would be considered offsite. However, they would not be public receptors because you are responsible for the safety of those who work in or visit your offices. Parking lots generally are not public receptors.

(CAA Q&A Database, March 1999)

IV. E. 8. Question: What is considered a recreational area?

Recreational areas would include land that is designed, constructed, designated, or used for recreational activities. Examples are national, state, county, or city parks, other outdoor recreational areas such as golf courses or swimming pools and oceans, lakes, and streams when used by the public for fishing, swimming, or boating. Public and private areas that are predictably used for hunting, fishing, bird watching, bike riding, hiking, or camping or other recreational use also would be considered recreational areas. You should consult with land owners, local officials, and the community to reach an agreement on a area’s status; your local emergency planning committee (LEPC) can help you with these consultations. EPA recognizes that some judgement is involved in determining whether an area should be considered recreational.

(CAA Q&A Database, March 1999)

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IV. F. 1. Question: The Risk Management Program rule requires owners or operators of covered processes to define in the risk management plan (RMP) the potential offsite public and environmental receptors within the impact range of identified worst case and alternative release scenarios. What is the definition of "environmental receptor"? What data sources are acceptable for identification of environmental receptors?

Answer: "Environmental receptor" is defined at 40 CFR §68.3 as "natural areas such as national or state parks, forests, or monuments; officially designated wildlife sanctuaries, preserves, refuges, or areas; and Federal wilderness areas" which could be exposed to an accidental release. A stationary source owner or operator may rely on information provided on local U.S. Geological Survey maps or on any data source containing U.S.G.S. data to identify these environmental receptors (61 FR 31720; June 20, 1996). Habitats of endangered and threatened species are not included in the definition of "environmental receptor" because information about the locations of these habitats is often not publicly accessible. Natural resource agencies will have access to submitted RMPs, and will be able to raise concerns with local officials about potential harm to critical habitats, as necessary. EPA hopes that potentially affected environmental receptors that are not specifically included will become the subject of dialogue on environmental risks between stationary sources and the environmental community.

(CAA Q&A Database, September 6, 1996)

IV. F. 2. Question: Are wetlands included in the definition of "environmental receptors"?

Answer: No. EPA has defined environmental receptors as natural or state parks, forests, or monuments; officially designated wildlife sanctuaries, preserves, refuges, or areas; and Federal wilderness areas, that are easily identified on local U.S. Geological survey maps (40 CFR §68.3). Therefore, wetlands would not be reported in the hazard assessment under 40 CFR §68.33. However, under the five-year accident history at 40 CFR §68.42 any known damage to a wetland would be reported as environmental damage.

(CAA Q&A Database, May 1997)

IV. F. 3. Question: A process covered under 40 CFR Part 68 is eligible for Program 1 requirements if it meets all of the criteria listed at 40 CFR §68.10(b). One of those criteria is that the distance to a toxic or flammable endpoint for a worst-case release assessment is less than the distance to any public receptor. Are rivers that are used for recreation covered as "public receptors"?

Answer: The final rule defines public receptor to mean "offsite residences, institutions (e.g. schools, hospitals), industrial, commercial, and office buildings, parks, or recreational areas inhabited or occupied by the public at any time without restriction by the stationary source where members of the public could be exposed to toxic concentrations, radiant heat, or overpressure, as a result of an accidental release" (40 CFR §68.3). A river would be included in this definition since it is likely to be used for recreational purposes where members of the public may be present.

(CAA Q&A Database, May 1997)

IV. F. 4. Question: For the worst-case and alternative release scenarios of an underground storage tank, should I consider any impact on groundwater, drinking water or soil?

Answer: No. As part of the worst-case and alternative release scenarios, you need to define the offsite impacts to the environment (40 CFR §68.33) by listing the environmental receptors that are withing your impact zone. "Environmental receptor" is defined at 40 CFR §68.3 as "natural areas such as national or state parks, forests, or monuments; officially designated wildlife sanctuaries, preserves, refuges, or areas; and Federal wilderness areas" which could be exposed to an accidental release. You only need to list the environmental receptors, not speculate what specific damage could occur as a result of an accidental release.

You should, however, consider impacts on groundwater, drinking water or soil in both the accident history for Program 1 eligibility criterion (40 CFR §68.10(b)(1)) and the five-year accident history required as part of the hazard assessment (40 CFR §68.42). For Program 1 eligibility, you must not have had an accidental release of a regulated substance in the past five years that caused any "response or restoration activities for an exposure of an environmental receptor." An accidental release that led to response or restoration of soil or groundwater of an environmental receptor, such as a park, would make a process ineligible for Program 1. For the hazard assessment five-year accident history, environmental damage is not limited to the defined environmental receptors. Events where there is any known environmental impact of any kind (e.g. fish or animal kills, lawn, shrub, or crop damage) must be included in the history (61 FR 31710; June 20, 1996). Therefore, any known damage to groundwater or soil must be reported in the five-year accident history.

( CAA Q&A Database, July 1997)

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IV. G. 1. Question: Should the owner or operator include accidental releases from processes containing listed substances below the threshold quantity in the five-year accident history required under the hazard assessment provisions of 40 CFR Part 68, Subpart B, and in the incident investigation requirements under 40 CFR Part 68, Subparts C and D?

Answer: No. The owner or operator of a stationary source subject to the risk management program regulations must include in the five-year accident history only those accidents from covered processes that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property damage or environmental damages (40 CFR §68.42(a)). "Covered process" is defined as a process that has a regulated substance present in more than a threshold quantity (40 CFR§68.3). Because the accident history is, by statute, an aspect of the hazard assessment, and the hazard assessment provisions apply only to covered processes, EPA believes that requiring the accident history to address accidental releases from processes not covered by this rule would be inconsistent with the structure of Part 68 (61 FR 31697; June 20, 1996). The incident investigation provisions (40 CFR §§68.60 and 68.81) are part of the Program 2 and Program 3 prevention programs. Similarly, these provisions apply only to accidental releases from a covered process that resulted in or could reasonably have resulted in a release that posed serious danger to public health or the environment.

(CAA Q&A Database, October 1996)

IV. G. 2. Question: Under the hazard assessment requirements of 40 CFR Part 68, Subpart B, an owner or operator must document a five-year accident history including all accidental releases from covered processes that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage (40 CFR §68.42(a)). If it is known that an accidental release from a covered process within the last five years has resulted in the death of livestock at a neighboring farm, must that event be reported in the five-year accident history?

Answer: Yes. The five-year accident history, required as a part of the hazard assessment under 40 CFR Part 68, Subpart B, must include all accidents resulting in any offsite property or environmental damage of which the stationary source owner or operator has knowledge. The death of animals off site due to an accidental release of a regulated substance from a covered process could be considered either environmental or property damage. Such an accident would therefore need to be included in the five-year accident history and documented as a known offsite impact under 40 CFR §68.42(b)(7).

(CAA Q&A Database, January 1997)

IV. G. 3. Question: Program 1 eligibility under 40 CFR §68.10(b) is contingent upon the process not having had an accidental release of a regulated substance that led to offsite death, injury, or response and restoration activities at an environmental receptor within five years prior to the risk management plan submission. Additionally, as part of the hazard assessment required under 40 CFR §68.42(a), sources are required to document all accidental releases from covered processes that resulted in onsite or offsite deaths, injuries, property damage, evacuations, sheltering in place, or environmental damage. Why are there differences in the accident history elements required for determining Program 1 eligibility and the hazard assessment?

Answer: The two accident histories serve different purposes. The purpose of the Program 1 eligibility criterion (40 CFR §68.10(b)(1)) is simply to ensure that the process in question has had no releases of a regulated substance that resulted in offsite impacts; onsite impacts are not relevant. In addition to meeting the accident history criterion, Program 1 sources must be located such that there are no public receptors within the distance to a toxic or flammable endpoint. The accident history acts as a confirmation that releases from Program 1 processes do not have the potential for offsite impact.

The five-year accident history under 40 CFR §68.42, required as part of the hazard assessment, provides data on all serious accidental releases from covered processes at the stationary source. Since releases with onsite impacts indicate safety problems that could lead to releases with offsite impacts, EPA requires these accidents to be reported in the five-year accident history.

Together, the accident history criterion for Program 1 eligibility and the five-year accident history required as part of the hazard assessment provide owners and operators an opportunity to demonstrate to the community ongoing excellence in accident prevention. These accident history requirements also provide an incentive to search for and implement ways, such as inventory reduction, to reduce the potential for offsite impacts associated with large scale accidental releases (61 FR 31675; June 20, 1996).

(CAA Q&A Database, January 1997)

IV. G. 4. Question: The hazard assessment requirements under 40 CFR Part 68, Subpart B include provision of a five-year accident history, as specified at §68.42. When does the five-year period begin?

Answer: The five-year accident history must include all accidental releases from covered processes meeting the criteria specified at 40 CFR §68.42 which have occurred within five years prior to the date of the risk management plan (RMP) submission. For example, if an RMP is submitted on June 1, 1999, the five-year accident history must cover the period between June 1, 1994 and June 1, 1999, to the extent that information prior to August 19, 1996 (the effective date of the rule) is known.

(CAA Q&A Database, January 1997)

IV. G. 5. Question: Under