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verification that the surrounding area is not explosive, verification that combustible materials are removed or covered appropriately, identification and closure of open vessels or ducts, and veritication that welded walls are not flammable.
Under the management of change section of the PSM standard employees are required to develop and implement documented procedures to manage changes in the process chemistry, process equipment, and operating procedures. Before a change occurs (except for replacement- in-kind), it must be reviewed to ascertain that it will not affect the safety of the operation. After the change has been made, all the affected employees are trained, and a pre-startup review is conducted.
The PSM standard mandates incident investigation. Employers must investigate all inci- dents that have or could have resulted in a major release or accident within 48 hours of the event. The regulation requires an investigation team composed of people, including operators, who are knowledgeable about the system. After the investigation, the employers are required to appropriately use the investigation recommendations.
The intent of the PSM element for emergency planning and response is to require em- ployers to respond effectively to the release of highly hazardous chemicals. Although the reg- ulation requires this activity for companies with more than 10 employees, this element should be part of a program for even the smallest organizations that handle hazardous chemicals.
Under the audits section of the PSM standard employers are required to certify that they have evaluated their compliance with the standard at least every three years. The recommen- dations from the audit must be followed. The audit reports need to be retained as long as the process exists.
The trade secrets section of the PSM standard ensures that all contractors are given all the information relevant to operating in the plant safely. Some personnel may need to sign secrecy agreements before they receive this information.
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than a specified threshold quantity of regulated highly hazardous chemicals. The RMP is a site responsibility (the site may have several processes), whereas PSM covers every covered process on the site.
The RMP has the following elements:
hazard assessment, prevention program,
emergency response program,
documentation that is maintained on the site and submitted to federal, state, and local authorities. This information is also shared with the local community.
The RMP document is updated when the process or chemistry changes or when a gov- ernmental audit requests an update. The first three parts of the regulation are described briefly in the following paragraphs. The fourth part, documentation, is self-explanatory.
Hazard assessment is a consequence analysis for a range of potential hazardous chemical releases, including the history of such releases at the facility. The releases must include the worst-case scenario and the more likely but significant accident release scenarios. A risk ma- trix can be used to characterize the worst-case and more likely scenarios.
The EPA requires the following consequence analyses: (1) A single worst-case release scenario is analyzed for all covered flammable materials on the site, and only one flammable substance is analyzed for other more likely scenarios; and (2) a single worst-case release sce- nario is analyzed for all toxic substances on the site, and more likely releases are analyzed for each toxic substance covered by the rule.
The worst-case scenario is based on releasing the entire contents of a vessel or piping sys- tem in a 10-minute period under worst-case meteorological conditions (F stability and 1.5 m/s wind speed). Passive mitigation measures (for example, dikes) can be used in the calculation process; therefore the release rate for liquid spills corresponds to the evaporation rate.
Alternative release cases for toxic substances cover scenarios with toxic concentrations beyond the fenceline. Alternative cases for flammable substances cover scenarios that may cause substantial damage off site and on site. The release scenarios that have a potential to reach the public are of the greatest concern. Those with no off-site potential damage are not required to be reported.
Dispersion model calculations are normally used to estimate downwind concentrations;
these concentrations are the basis for determining the consequences resulting from toxicity, fires, and/or explosions. For those not interested in using dispersion models, the standard in- cludes lookup tables for all the listed substances to help a facility determine the impact dis- tances for specific release scenarios.
The RMP requires only an analysis of the consequence and not the probability. There- fore the results are not a true determination of risk, because risk is composed of both conse-
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Table 3-4 Comparison of the PSM and RMP Prevention Programs
PSM program (OSHA) RMP (EPA)
Process safety information Process safety information Process hazards analysis Hazard evaluation
Operating procedures Standard operating procedures Employee participation (No equivalence)
Training Training
Contractors (No equivalence)
Pre-startup review Pre-startup review
Mechanical integrity Maintenance
Hot work permit (No equivalence)
Management of change Management of change
Incident investigations Accident investigations Emergency planning and response Emergency response
Compliance audits Safety audits
Trade secrets (No equivalence)
(No equivalence) Risk assessment
quence and probability. A more detailed description of the required consequence analyses can be found el~ewhere.~
The second requirement of the RMP is a prevention program. The prevention program has 11 elements, compared to the 14 elements of the PSM standard. As shown in Table 3-4, many of these elements are duplicated. Fortunately, the EPA made a deliberate attempt to re- tain the same requirements wherever possible, although differences exist because the EPA and OSHA have different responsibilities. The first column in Table 3-4 lists each element of the PSM program, and the second column shows the corresponding element of the prevention pro- gram (some elements have no equivalence).
The emergency response program delineates the steps to be taken by the facility's em- ployees in response to accidental releases of hazardous materials. It also establishes proce- dures for notifying the local community and the appropriate emergency response agencies.
Training is for all employees on the topics relevant to emergency response. The requirements include drills to test the plan and to evaluate its effectiveness, and the plan must be revised based on the findings of these drills.
The plan must be coordinated with local emergency response plans developed by Local Emergency Planning Committees (LEPCs) and local emergency response agencies. As with similar OSHA regulations, the Resource Conservation and Recovery Act (RCRA), and the 4Daniel A. Crowl, "Consequence Modeling for the EPA Risk Management Plan (RMP)," Process Safety Progress (Spring 1997), pp. 1-5.
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Spill Prevention Control under the Clean Water Act, the emergency response plan must be maintained at the facility and must include descriptions of all mitigating systems.