Tempe Distribution Center - Executive Summary
Accidental Release Prevention and Emergency Response Policies |
The management and staff of the Tempe Distribution Center are committed to operating the Distribution Center with the highest regard for the safety of the public, Distribution Center personnel, and the environment. To ensure the safety of the public, Distribution Center personnel, and the environment, the Distribution Center has implemented a management system that integrates the elements of OSHA's Process Safety Management (PSM) standard, 29 CFR 1910.119 and EPA's Risk Management Program (RMP) rule, 40 CFR part 68. The policies and procedures integrated under the Distribution Center's management system specifically address prevention of the release of anhydrous ammonia, and emergency response to an accidental release of ammonia.
Description of Processes, and Regulated Substances Handled at the Tempe Distribution Center
The Tempe Distribution Center operates several refrigerated warehouses and freezers. Anhydrous ammon
ia is used as a refrigerant in the mechanical compression refrigeration system at the Tempe Distribution Center. Ammonia is handled in a closed-loop process that consists of the following general stages: Liquid storage; Expansion; Evaporation; Compression; and Condensation. The Tempe Milk Plant is served by the same ammonia refrigeration system.
Mechanical refrigeration is a physical process, rather than a chemical process: the ammonia undergoes no chemical changes in the refrigeration cycle. Heat is removed from the product being refrigerated or frozen as ammonia changes phase from liquid to vapor. By reliquefying the ammonia vapor, the ammonia can be used continuously in the refrigeration cycle.
The ammonia refrigeration system is the only process at the Tempe Distribution Center which is subject to the EPA RMP rule (and the OSHA PSM standard). Anhydrous ammonia is the only regulated substance handled in the ammonia refrigeration system.
At ambient temperature and pressure,
ammonia is a colorless gas with a characteristic, irritating odor. Ammonia is highly soluble in water. Ammonia is the third highest-volume chemical produced in the United States. The chemical formula of ammonia is NH3. Anhydrous ammonia is handled both as a pressurized liquid at ambient temperature and as a refrigerated liquid at or below ambient pressure within the Tempe Distribution Center refrigeration system.
The toxic endpoint to which the consequences of ammonia releases must be analyzed is 0.14 mg/L. This is approximately equal to 200 ppmv, which corresponds to the American Industrial Hygiene Association's Emergency Response Planning Guideline level 2 (ERPG-2) for ammonia. ERPG-2 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.
t-case Release Scenario, and Alternative Release Scenarios
The Distribution Center's worst-case release scenario consists of a total release of the maximum allowable inventory of the High Pressure Receiver over a duration of ten minutes. The maximum allowable inventory is approximately 13,000 pounds. The maximum allowable inventory is the largest quantity of ammonia that could be contained in the High Pressure Receiver without allowing the vessel to become liquid-full at 115 degrees Fahrenheit, which corresponds to the vessel's pressure relief set point of 250 psig.
The High Pressure Receiver is located within a building. In accordance with "Risk Management Program Guidance for Ammonia Refrigeration," the release rate to the surroundings was calculated as 440 lbs/min, with a duration of 10 minutes.
EPA's "Risk Management Program Guidance for Ammonia Refrigeration" was used to evaluate the worst-case release scenario. The following inputs were applied: wind speed, 1.5 m/s; stabi
lity class, F; topography, urban; release duration, 10 minutes; release rate, 440 lbs/min. The maximum distance to the toxic endpoint was evaluated as 0.8 miles.
Using Landview III, the population within 0.8 miles of the release point was estimated as 4,700. The following types of public receptors lie within 0.8 miles of the release point: schools, residences, and major commercial/office/industrial areas. There are no environmental receptors, as defined in the RMP rule, within 0.8 miles of the release point.
EPA's "Risk Management Program Guidance for Ammonia Refrigeration" was used to evaluate the alternative release scenario. The Distribution Center's alternative release scenario consists of a pressurized liquid ammonia release through a <" diameter hole in outdoor piping downstream from the evaporative condenser. The release is assumed to persist for 10 minutes prior to isolation (which can safely and rapidly be accomplished remotely). The pressure in the piping is assumed
to be 130 psig, at a temperature of 25 degrees C. Under these conditions, the release rate was found to be 110 lbs/min, and the total quantity released was 1100 lbs.
The following inputs were assumed: wind speed, 3 m/s; stability class, D; topography, urban. Combining these inputs with the release rate described above, the distance to 200 ppmv ammonia was found to be 0.1 mi. Note that the EPA guidance conservatively assumes that the release occurs at ground level. A release from the elevation of the evaporative condenser would actually be accompanied by dilution due to vertical dispersion, resulting in a somewhat shorter distance to the toxic endpoint.
The population within 0.1 is estimated to be 70. The following types of public receptors lie within the distances to the endpoints described above: residences, and major commercial/office/industrial areas. There are no environmental receptors, as defined in the RMP rule, within 0.1 miles of the release point.
The Distribution Center's accidental release prevention program consists of the following elements: Process Safety Information; Process Hazard Analysis; Operating Procedures; Training; Contractors; Pre-Startup Safety Review; Mechanical Integrity; Hot Work Permit; Management of Change; Incident Investigation; Compliance Audits; and Employee Participation. The purpose and scope of each element is briefly described below.
Process Safety Information - The purpose of compiling the required Process Safety Information is to enable Distribution Center personnel who work with the ammonia refrigeration system to identify and understand the hazards posed by ammonia refrigeration. The Distribution Center's Process Safety Information procedure addresses: Information requirements pertaining to the hazards of ammonia; Information requirements pertaining to the technology of the process; Information requirements pertaining to the equipment in the process; and Process Safety I
nformation accessibility requirements.
Process Hazard Analysis - The purpose of the Distribution Center's PHA procedure is to describe the method for conducting process hazard analyses of the Distribution Center's ammonia refrigeration system. The Distribution Center's PHA procedure addresses: PHA methodology; PHA scope; PHA team requirements; Employee participation requirements; System established to promptly address the PHA team's recommendations; PHA update and revalidation requirements; PHA report retention requirements; and PHA report distribution requirements.
Operating Procedures - The purpose of the Distribution Center's Operating Procedure policy is to provide a method for developing and implementing written operating procedures to give clear instructions for safely conducting activities associated with the Distribution Center's ammonia refrigeration system. The Distribution Center's Operating Procedure policy addresses: Development and implementation of written procedur
es to provide clear instructions for safely conducting activities involved in each covered process; Development and documentation of process operating limits; Development and documentation of process safety and health considerations; Operating procedure accessibility requirements; Operating procedure review requirements; and Safe work practice requirements for employees and contractors to provide for control of hazards during operations.
Training - The purpose of the Distribution Center's Training procedure is to ensure that personnel involved in operating the Distribution Center's ammonia refrigeration system have received and understood training in: an overview of the Distribution Center's ammonia refrigeration system; the operating procedures required in the Operating Procedures element of the Distribution Center's PSM program; safety and health hazards associated with the Distribution Center's ammonia refrigeration system; and applicable safe work practices. The Distribution Cen
ter's Training procedure addresses: Initial training requirements; Refresher training requirements; Documentation of employee training; and Testing to ensure that required training has been understood.
Contractors - The purpose of the Distribution Center's Contractors procedure is to establish a method for ensuring that all contractors are adequately trained to perform work on or near the Distribution Center's ammonia refrigeration system. The Distribution Center's Contractors procedure addresses the responsibilities of the Distribution Center and the contract employer with respect to ensuring the safety of contractors working on or near the Distribution Center's ammonia refrigeration system.
Pre-Startup Safety Review - The purpose of the Distribution Center's Pre-Startup Safety Review procedure is to ensure that new or modified facilities that handle regulated substances are safely started up. The Distribution Center's Pre-Startup Safety Review procedure (PSSR) addresses: PSSR C
hecklist completion prior to startup of new or modified facilities; The method for determining when a PSSR shall be performed, and PSSR Team selection; The system to ensure that new Process Safety Information has been compiled; The system to ensure that all materials and construction are in accordance with design specifications; The system to ensure that all safety, operating, maintenance, and emergency procedures are in place and adequate; The system to ensure that a Process Hazard Analysis has been performed for new facilities, and that recommendations have been addressed prior to startup; The system to ensure that Management of Change requirements are met prior to start-up of modified facilities; The system to ensure that operations and maintenance employees are trained prior to start-up; and Documentation of the Pre-Start Safety Review.
Mechanical Integrity - The purpose of the Distribution Center's Mechanical Integrity policy is to establish the requirements of the Mechanical Int
egrity program at the Tempe Distribution Center. The purpose of the Mechanical Integrity program is to ensure that process equipment used to handle anhydrous ammonia is designed, constructed, and maintained to minimize the risk of accidental release. The Distribution Center's Mechanical Integrity program addresses the following activities as they relate to the Distribution Center's ammonia refrigeration system: Training in the Distribution Center's ammonia refrigeration system and its hazards, and in the safe conduct of maintenance activities; Inspection and testing; Correcting deficiencies in equipment; and Quality assurance in fabrication, installation, and maintenance.
Hot Work Permits - The purpose of the Distribution Center's Hot Work Permit procedure is to define how Hot Work Permits are issued and to ensure compliance with permit requirements before and during hot work. The Distribution Center's Hot Work Permit procedure addresses: General requirements; The Hot Work Permit
; Authorization of hot work; Fire prevention precautions; and Fire watchers.
Management of Change - The purpose of the Distribution Center's Management of Change procedure is to establish the Distribution Center's requirements for managing changes to the Distribution Center's ammonia refrigeration system. This procedure provides direction in identifying, reviewing, and authorizing process changes prior to their implementation in order to minimize their potential impact on safety and health. The Distribution Center's Management of Change Procedure addresses the following: Identifying process changes; Reviewing process changes; Training necessitated by process changes; Updating Process Safety Information; Updating operating procedures; and Authorizing process changes. Specific actions included within reviewing process changes are: documenting the technical basis for the proposed change; assessing the impact of the proposed change on safety and health; modifying operating procedures
, as necessary; and documenting and tracking the intended duration of the change (temporary vs. permanent).
Incident Investigation - The purpose of the Distribution Center's Incident Investigation procedure is to provide a method for reporting, investigating, and preventing reoccurrence of incidents that result in or could reasonably have resulted in a catastrophic release of ammonia. The Distribution Center's Incident Investigation procedure addresses: Reporting incidents; The procedure for initiating an incident investigation; The establishment of an Incident Investigation Team, and requirements for the selection of Team members; Investigating the incident; Preparation of the Incident Investigation Report and the minimum requirements of the Report; The system established to promptly address and resolve the report findings and recommendations; and The method for reviewing the findings of the Incident Investigation with all operating, maintenance, and other affected personnel (incl
uding contract employees) whose work assignments are relevant to the findings.
Compliance Audits - The purpose of the Distribution Center's Compliance Audits procedure is to establish the requirements for an audit that verifies that the Distribution Center is meeting the requirements of OSHA's Process Safety Management (PSM) standard, and EPA's Risk Management Program rule. The Distribution Center's Compliance Audits procedure requires triennial review of the Distribution Center's PSM program/RMP Prevention Program procedure documents, and evaluation of the implementation of these procedures by conducting records reviews, employee interviews, and field inspections. The Distribution Center's Compliance Audit procedure also requires that recommendations be formulated to resolve any identified deficiencies. The Distribution Center's Compliance Audits procedure addresses: Pre-audit activities; Conduct of the PSM program/RMP Prevention Program compliance audit; and Post-audit activitie
s, including taking action to resolve any identified deficiencies.
Employee Participation - The purpose of the Distribution Center's Employee Participation procedure is to document the method of actively involving Distribution Center employees in the development and conduct of the Distribution Center's Process Safety Management elements. The purpose of involving employees in the development and conduct of the Distribution Center's PSM elements is to foster commitment to the enhancement of process safety. The Distribution Center's Employee Participation procedure addresses: The method of consulting employees (and their representatives) on the conduct and development of each element in the Distribution Center's process safety management program; and The method for providing employees (and their representatives) access to all process safety management documents and records.
Five-year Accident History
Over the past five years, the Tempe Distribution Center has not had any ammonia rel
eases that resulted in deaths, injuries, property damage, environmental damage, or offsite evacuations.
Emergency Response Program
The Distribution Center has an emergency action plan that addresses the following: Evacuation; Emergency release notification; and First aid/medical management. The Distribution Center's emergency response program is coordinated with the local fire department.
All Distribution Center employees receive training in the emergency action plan. The local fire department is invited to participate in the Distribution Center's emergency action plan drills, in order to familiarize fire department personnel with the Distribution Center's process and emergency procedures.
Planned Changes to Improve Safety
As a result of recent modification of the Tempe Distribution Center's ammonia refrigeration system, the Distribution Center has just become subject to the PSM standard and the RMP rule. The Distribution Center has established new PSM/prevention program eleme
nts. The new program elements have been integrated into a management system framework, in accordance with internationally recognized principles of total quality management. The management system is designed to ensure implementation of each program element, in compliance with the OSHA PSM standard, and the EPA RMP rule. Authority, responsibility, and accountability are clearly and specifically assigned to Distribution Center management, supervision, and staff. The means of documenting compliance have been improved for each prevention program element.