Montour Steam Electric Station - Executive Summary |
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EXECUTIVE SUMMARY Accident Release Prevention and Emergency Response Policies PP&L's Risk Management Planning policy provides a unified approach to prevent accidental releases of chemicals through the integration of engineering controls, administrative controls and administrative procedures. All applicable procedures from the U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to. PP&L has developed accidental release mitigation policies specific to the covered process and chemical which are supported by other safety policies implemented by the plant. The PP&L emergency response program policy dictates the implementation of response plans detailed specifically to the PP&L covered process and chemical and to the emergency response services available in the community. An offsite emergency response plan, developed by the Montour County Emergency Management Agency, has been in-place for other chemicals at the site. That plan will be modified with support of PP& L, to include the covered chemical. Stationary Source and Regulated Substance Handled The PP&L facility, located in Montour County is a fossil fuel based steam and electric plant. Anhydrous ammonia is used to reduce nitrogen oxide emissions from combustion off-gas. NOx is reduced by mixing and reacting with ammonia. The anhydrous ammonia system includes railcars, and tanker trucks, bulk tanks, process piping, various safety & monitoring systems, compressors, and pumps. This system is typically manned, and is monitored daily by operators. The system is to be used on a seasonal basis, up to seven months a year. Maintenance employees are on staff to respond to any alarms and to maintain the system. The offsite consequence analysis includes consideration of two release scenarios for this chemical, the "worst case scenario" and an "alternate case scenario". The worst case scenario is defined by EPA and states that "the owner or operator shall assume that the ... maximum quantity i n the largest vessel ... is released as a gas over 10 minutes," due to an unspecified failure. The alternate case scenario is defined as "more likely to occur than the worst case release scenario". Worst and Alternate Case Scenarios Atmospheric dispersion modeling has been performed to determine the potential distance traveled by the anhydrous ammonia before its concentration decreases to the "toxic endpoint" specified in 40 CFR Part 68 Appendix A, which is 0.14 mg/L of air (200 ppm). The residential population within a circle with a radius corresponding to the toxic endpoint distance has to be defined, "to estimate the population potentially affected". The worst case scenario involves a failure of the bulk ammonia tank, containing 272,320 lbs. of ammonia, released as a gas over a 10-minute period. EPA mandated meteorological conditions, namely Stability F, wind speed of 1.5 meters per second, highest daily local temperature and average humidity of 71% were used for the worst cas e release scenario. The facility is located in a rural area. Modeling results indicate that the worst case release scenario would encompass population and environmental receptors. The alternate case scenario involves a breech (25% rupture) in the two-inch liquid ammonia line at a connection during a tanker transfer. A conservative duration time factor of 10 minutes was used to account for the time it may take the operator of the tanker to become aware of the release and to terminate. Average meteorological conditions were used for the alternate case release scenario modeling. Results indicate that the alternate case would also encompass offsite population. Administrative controls have been developed to minimize the potential for release and consequences. These controls consist of storage volume limitations, dikes around and a roof overhead of the storage tanks, pumps and compressors, equipment operating sequencing, specialized equipment operating and maintenance procedures, and training. Mitigation measures to be employed consist of process equipment perimeter ammonia detectors, overhead sprinkler system to knock down ammonia gas, and computerized alarms and interlocks. General Accidental Release Prevention Program and Prevention Steps The general accidental release program for anhydrous ammonia is as follows: * Operation, maintenance, safety, and emergency response training for employees who operate, maintain, inspect, and work with the ammonia system. * Effective, detailed procedures for maintenance, operation and troubleshooting of the systems. * Preventative maintenance programs in accordance with manufacturers' recommendations and/or industry standards to maintain the mechanical integrity of the system. * A Management of Change program that identifies potential concerns and addresses these concerns before system changes are implemented. * A compliance audit program that reviews conformance to the standards. * Contracting of vendors with ammonia handl ing experience, written safety policies, and training in ammonia use, awareness, and response. * Effective Management support of all program elements. Five Year Accident History The operation is new; there have been no accidental releases of anhydrous ammonia. Emergency Response Program PP&L has a comprehensive emergency response plan, including an Off-Site plan that has been developed in coordination with the Montour County Local Emergency Planning Commission (LEPC). PP&L has contracted emergency responders trained in accordance with the appropriate levels of response; responders who can specifically handle potential releases of anhydrous ammonia. These responders are trained to handle potential releases of anhydrous ammonia. Specific on-site response plans for dealing with releases of anhydrous ammonia. The emergency response team is well equipped with chemical sensing equipment; personal protective equipment; offensive and defensive strategy tools & equipment; radio communic ation; pre-determined response checklists for Incident Command, Safety/Science Officer and Decon Officer; emergency decon and medical supplies; and decon supplies. Planned Changes to Improve Safety Procedures were created and engineering improvements were recommended during the system design phase to improve the safety and reliability of the system. A brief list of the changes made during this phase include: * Provide local alarm near pump truck and railcars for manual shutdown on separate power system. * Assure height/location of detectors for quick detection of liquid (ground level) and upward jet release from railcar. * Add fogging system nozzles around railcar and tank truck unloading areas. EXECUTIVE SUMMARY Accident Release Prevention and Emergency Response Policies PP&L's Risk Management Planning policy provides a unified approach to prevent accidental releases of chemicals through the integration of engineering controls, administrative controls and administrative proce dures. All applicable procedures from the U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to. PP&L has developed accidental release mitigation policies specific to the covered process and chemical which are supported by other safety policies implemented by the plant. The PP&L emergency response program policy dictates the implementation of response plans detailed specifically to the PP&L covered process and chemical and to the emergency response services available in the community. An offsite emergency response plan, developed by the Montour County Emergency Management Agency, has been in-place for other chemicals at the site. That plan will be modified with support of PP&L, to include the covered chemical. Stationary Source and Regulated Substance Handled The PP&L facility, located in Montour County is a fossil fuel based steam and electric plant. Anhydrous ammonia is used to reduce nitrogen oxide emissions from combustion off-gas. NOx is reduced by mixing and reacting with ammonia. The anhydrous ammonia system includes railcars, and tanker trucks, bulk tanks, process piping, various safety & monitoring systems, compressors, and pumps. This system is typically manned, and is monitored daily by operators. The system is to be used on a seasonal basis, up to seven months a year. Maintenance employees are on staff to respond to any alarms and to maintain the system. The offsite consequence analysis includes consideration of two release scenarios for this chemical, the "worst case scenario" and an "alternate case scenario". The worst case scenario is defined by EPA and states that "the owner or operator shall assume that the ... maximum quantity in the largest vessel ... is released as a gas over 10 minutes," due to an unspecified failure. The alternate case scenario is defined as "more likely to occur than the worst case release scenario". Worst and Alternate Case Scenarios Atmospheric dispersion modeling has been p erformed to determine the potential distance traveled by the anhydrous ammonia before its concentration decreases to the "toxic endpoint" specified in 40 CFR Part 68 Appendix A, which is 0.14 mg/L of air (200 ppm). The residential population within a circle with a radius corresponding to the toxic endpoint distance has to be defined, "to estimate the population potentially affected". The worst case scenario involves a failure of the bulk ammonia tank, containing 272,320 lbs. of ammonia, released as a gas over a 10-minute period. EPA mandated meteorological conditions, namely Stability F, wind speed of 1.5 meters per second, highest daily local temperature and average humidity of 71% were used for the worst case release scenario. The facility is located in a rural area. Modeling results indicate that the worst case release scenario would encompass population and environmental receptors. The alternate case scenario involves a breech (25% rupture) in the two-inch liquid ammonia line at a connection during a tanker transfer. A conservative duration time factor of 10 minutes was used to account for the time it may take the operator of the tanker to become aware of the release and to terminate. Average meteorological conditions were used for the alternate case release scenario modeling. Results indicate that the alternate case would also encompass offsite population. Administrative controls have been developed to minimize the potential for release and consequences. These controls consist of storage volume limitations, dikes around and a roof overhead of the storage tanks, pumps and compressors, equipment operating sequencing, specialized equipment operating and maintenance procedures, and training. Mitigation measures to be employed consist of process equipment perimeter ammonia detectors, overhead sprinkler system to knock down ammonia gas, and computerized alarms and interlocks. General Accidental Release Prevention Program and Prevention Steps T he general accidental release program for anhydrous ammonia is as follows: * Operation, maintenance, safety, and emergency response training for employees who operate, maintain, inspect, and work with the ammonia system. * Effective, detailed procedures for maintenance, operation and troubleshooting of the systems. * Preventative maintenance programs in accordance with manufacturers' recommendations and/or industry standards to maintain the mechanical integrity of the system. * A Management of Change program that identifies potential concerns and addresses these concerns before system changes are implemented. * A compliance audit program that reviews conformance to the standards. * Contracting of vendors with ammonia handling experience, written safety policies, and training in ammonia use, awareness, and response. * Effective Management support of all program elements. Five Year Accident History The operation is new; there have been no accidental releases of anhydrous amm onia. Emergency Response Program PP&L has a comprehensive emergency response plan, including an Off-Site plan that has been developed in coordination with the Montour County Local Emergency Planning Commission (LEPC). PP&L has contracted emergency responders trained in accordance with the appropriate levels of response; responders who can specifically handle potential releases of anhydrous ammonia. These responders are trained to handle potential releases of anhydrous ammonia. Specific on-site response plans for dealing with releases of anhydrous ammonia. The emergency response team is well equipped with chemical sensing equipment; personal protective equipment; offensive and defensive strategy tools & equipment; radio communication; pre-determined response checklists for Incident Command, Safety/Science Officer and Decon Officer; emergency decon and medical supplies; and decon supplies. Planned Changes to Improve Safety Procedures were created and engineering improveme nts were recommended during the system design phase to improve the safety and reliability of the system. A brief list of the changes made during this phase include: * Provide local alarm near pump truck and railcars for manual shutdown on separate power system. * Assure height/location of detectors for quick detection of liquid (ground level) and upward jet release from railcar. * Add fogging system nozzles around railcar and tank truck unloading areas. |