Pasadena Water & Power Broadway Power Plant - Executive Summary |
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ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES City of Pasadena Water & Power Department (PWP) employees conduct ongoing inspections, testing, and replacement of the critical items in the aqueous ammonia system. The aqueous ammonia system is monitored during (at least) daily rounds by a PWP employee. Typically, the Power Plant operators perform cursory facility inspections twice per shift, or six times per day. Once identified, PWP will fix or outsource any system deviation that is noted. In any case, a record of the maintenance or work performed on the system is maintained by the Plant Supervisor. PWP has an emergency action plan in effect. The Emergency Action Plan (Plan) is detailed in the Emergency Response Program section of the CalARP document, which is maintained at the facility and updated as necessary. This Plan was designed to meet the following objectives: 1.) To save lives. 2.) To minimize and avoid injuries. 3.) To protect the environment. 4.) To minimize property damage. The Plan provides the response organization and notification procedures, evacuation routes, aqueous ammonia health hazards, and mitigation procedures which will be implemented to respond effectively to emergency situations that may arise at the facility. This Plan is reviewed and updated at least once per year. This Plan was reviewed and updated to ensure compliance with the CalARP and RMP regulations, as well as to incorporate facility changes. PWP has coordinated emergency response efforts with the local fire department, Pasadena Fire Department. In the case of an aqueous ammonia-related emergency, it is the policy of PWP to evacuate the employees and to allow the fire department to respond to the emergency (potentially with the assistance of trained facility personnel). PWP also plans to contract a private company to be available for aqueous ammonia emergency response situations. STATIONARY SOURCE AND REGULATED SUBSTANCE The City of Pasad ena Water & Power Department Broadway Power Plant is located at 130 Wallis Street, Pasadena, California 91105. The facility is located at the southwest corner of Arroyo Parkway and Glenarm Street, at the northern end of the 110 freeway. The area surrounding the facility is primarily light commercial and residential. The facility is surrounded by a chain link fence with locked gates. Visitors are required to check in with facility personnel upon arrival. The Broadway Power Plant Unit B-3 is a 71 MW unit that was placed in commercial operation in 1965. The Selective Catalytic Reduction (SCR) system was installed in 1994. The facility uses aqueous ammonia to catalytically reduce boiler flue gas nitrogen oxide (NOx) emissions to elemental nitrogen and water. The maximum intended inventory of aqueous ammonia at the Broadway Power Plant is 12,000 gallons (89,600 pounds). Aqueous ammonia, 29.4% weight anhydrous ammonia, is used at the City of Pasadena Power Plant in the Unit B-3 St eam Plant Selective Catalytic Reduction (SCR) system to help maintain air quality compliance of the emission stack, specifically, reducing NOx (NO and NO2) emissions. Depending on which fuel is burned, the SCR system provides a reduction efficiency of between 60-90%. When in operating mode, the aqueous ammonia system is automatically controlled based on system demand. The aqueous ammonia is stored in a 12,000 gallon tank inside a bermed containment area equipped with a manual drain. The liquid aqueous ammonia is pulled from the tank through the ammonia shut off valve by two pumps. It then travels through double walled piping, underground, to the first level of the Power Plant. There it flows through a strainer manifold and then travels up to the fifth level where it flows through a back pressure regulator control valve, a flow control valve to the vaporizer and then the injection grid. The catalyst bed provides the surface area for the SCR reactions to occur. The ammonia shut off valve remains open based on several permissive conditions including, but not limited to boiler load, reactor temperature, ammonia storage tank level, and metering pump operation. The aqueous ammonia is mixed with compressed air prior to entering the vaporizer where it is mixed with hot blower air and then fed to either the economizer superheat-side or the economizer reheat-side of the ammonia injection grid in the combustion exhaust stack. The NOx in the flue gas reacts with ammonia in the SCR reactor catalyst layers to form harmless elemental nitrogen and water. The elemental nitrogen and water remain in the flue gas as it passes through the stack to the atmosphere. The SCR reactor is designed for a NOx reduction efficiency of 89.3% when firing natural gas. The SCR system is equipped with various automatic process controls which ensure safe and efficient operation of the SCR reactor, vaporizer, metering pumps, shut-off and regulating valves. In addition, pressure relief valv es automatically engage in the event the system experiences a very high pressure situation. In case of an ammonia leak, four ammonia sensing devices will provide an alarm locally and in the control room. HAZARD ASSESSMENT SUMMARY * Worst Case Release Result Summary Scenario Description: Release of the maximum quantity of aqueous ammonia that can be stored in a vessel (the liquid storage tank) - 12,000 gallons (90,000 pounds) in 10 minutes. The liquid is assumed to leak into the concrete berm (passive mitigation) that surrounds the tank and then evaporate (rate = 34 lbs/min). The most pessimistic meteorological conditions were used: 1.5 meters per second wind speed, and F stability. The Risk Management Program Guidance for Waste Water Treatment Plants reference tables were used to determine the maximum distance to the toxic endpoint of 200 ppm in urban conditions. This release reaches off site and may impact population receptors. No environmental receptors were affecte d by this potential release. * Alternative Release Result Summary Scenario Description: A release of aqueous ammonia resulting from a ? inch diameter hole in the liquid piping. The evaporation rate of the pooled liquid aqueous ammonia is calculated to be 33.0 pounds per minute. The meteorological conditions used were 3 meters per second wind speed, and D stability. The Risk Management Program Guidance for Waste Water Treatment Plants reference tables were used to determine the maximum distance to the toxic endpoint of 200 ppm. This release reaches off site and may impact population receptors. No environmental receptors were affected by this potential release. ACCIDENTAL RELEASE PREVENTION PROGRAM AND CHEMICAL-SPECIFIC PREVENTION STEPS The storage of aqueous ammonia at the PWP Broadway Power Plant is governed by many safety features. Much of the safety of the process is inherent in the policies and procedures that govern the operation of the process. For example, the Broadway Power Plant operates in accordance with the California Accidental Release Prevention (CalARP) Program. The aqueous ammonia system is checked by operators on a daily basis. The Broadway Power Plant maintains tight control of its aqueous ammonia system through various process controls and monitors. In the event that the primary engineering or administration controls at the facility fail and result in a release of aqueous ammonia, there are three mechanisms at the facility to minimize the impact: 1) ammonia vapor detectors, 2) liquid sensor, and 3) associated alarms. There are four vapor detectors located in the following locations throughout the system: Bermed Storage Area, Feed Pump Skid, Vaporizer Area, Catalyst Expansion Joint. The ammonia sensors activate a local alarm and an alarm in the control room that is always manned. The liquid sensor is located in the Underground Secondary Containment area. All ammonia detectors provide an alarm to alert operators. Other aut omatic protections that are designed to mitigate or prevent a release of aqueous ammonia include: a containment berm surrounding the aqueous ammonia tank sized to hold the entire contents of the tank, double walled piping from the pump discharge to the stack, and a valve that will automatically engage to relieve pressure or vacuum (negative pressure) in the tank. The pressure relief/vaccum breaker setpoints are 25 psig/-0.125 psi. FIVE YEAR ACCIDENT HISTORY In the previous five years (since August 1995), there have been no aqueous ammonia accidents at the facility. EMERGENCY RESPONSE PROGRAM PWP has an emergency action plan in effect. The Emergency Action Plan (Plan) is detailed in the Emergency Response Program section of the RMP document, which is maintained at the facility and updated as necessary. This Plan was designed to meet the following objectives: 1.) To save lives. 2.) To minimize and avoid injuries. 3.) To protect the environment. 4.) To minimize prope rty damage. The Plan provides the response organization and notification procedures, evacuation routes, aqueous ammonia health hazards, and mitigation procedures which will be implemented to respond effectively to emergency situations that may arise at the facility. This Plan is reviewed and updated at least once per year. This Plan was reviewed and updated to ensure compliance with the CalARP and RMP regulations, as well as to incorporate facility changes due to personnel turnover. PWP has coordinated emergency response efforts with the local fire department, Pasadena Fire Department. In the case of an aqueous ammonia-related emergency, it is the policy of PWP to evacuate the employees via the Public Address system and to allow the fire department to respond to the emergency (potentially with the assistance of trained facility personnel). PWP also has an open contract with a company to assist with the cleanup process. The facility is also part of a city-wide emergency protocol called the Emergency Operations Center, or EOC. Developed by the State of California, standardized operating procedures have been established to deal with large-scale emergencies. These methods include financial accountability, mutual aid agreements, decision-making strategies, etc. Employees are trained to respond to small spills and incidents. For large spills or incidents, staff are instructed to notify, evaluate hazards, contain the leak or spill (if safe), shut off feed valves (if possible) and evacuate the area. For large incidents, the local emergency responders would be notified and brought in to assist. PWP staff would then provide technical support to the local emergency responder's Incident Command System (ICS). The IC for the City of Pasadena is the Fire Department. Pasadena FD is a member organization that would be called in to respond to a chemical release or incident. PLANNED CHANGES TO IMPROVE SAFETY The Hazard Review provided mitigation measures to improve s afety at the City of Pasadena Water & Power Broadway Power Plant located at 130 Wallis Street, Pasadena, California 91105. All recommendations are scheduled to be complete by July 31, 2001. A Seismic Assessment was also completed that yielded no recommended changes to improve safety. * Hazard Review R01 Incorporate response procedures for evacuation notification in the emergency response program (i.e. using the Public Address system to evacuate or isolate the area). R02 Review Plant training program for all employees. At a minimum, ensure that all employees are aware that aqueous ammonia is on site (Hazard Communication / Awareness training). All employees need to know who to contact if they smell ammonia and how to evacuate. R03 Review Plant training program for operators/maintenance personnel. Operators and/or Maintenance personnel may need First Responder Training to Operations level (minimum). Review on-the-job training for operators that are involved with the SCR System (i.e. Fill Procedures, Startup, Shut down). R04 Provide "Grandfather" certification for existing operators to satisfy initial training requirements. R05 In the External Events Analysis, review the maximum daily temperature and the likelihood of a release through the relief valve. R06 Check with La Roche regarding the delivery truck pump capacity. (It may be too low to make a difference.) R07 Check manufacturer's recommendations regarding relief valve maintenance/replacement (some industry groups recommend replacement or recertification every five years). R08 Include ammonia sensors in a preventive maintenance program. Conduct a live test of the sensor device using an ammonia solution to ensure that the alarms activate (annually). R09 Conduct a visual inspection of the tank and piping once per year. Examine the connections, fittings, etc. Document this inspection and determine whether or not painting is required. This should be included in the pr eventive maintenance program. R10 In the event that work must be performed inside the tank, ensure that there is a complete procedure to flush the tank of ammonia vapors prior to entry. R11 Examine training program/respiratory protection program/PPE requirements for personnel involved in the operation and maintenance of the aqueous ammonia process equipment. R12 Calculate size of pump skid containment area to determine the length of time a release could go undetected before it overflows the containment berm. R13 Include the PSL 3203 in the preventive maintenance program. The O&M Manual states that the device should be tested annually. Maintenance needs to investigate how to test the pressure switch and then how often to conduct the test. R14 Review maintenance schedules and prepare a preventive maintenance program that incorporates manufacturer's recommendations and facility history. Utilize a checklist to document visual inspections. R15 Evaluate the conseque nces associated with a release of 5 gallons per hour for 8 hours (40 gallons). R16 Review confined space program and evaluate the tunnel and vault areas. These areas may require that the Plant acquire an ammonia detector device (hand held, dreager, etc.). Company policy is that control room operator is notified prior to an operator entering the vault / tunnel area. This has been a topic during safety meetings (March 2000) to review this company policy of notifying the control room. R17 Verify that the piping in the tunnel is properly labeled. R18 Document preventive maintenance requirements for the air side of the system. R19 Review preventive maintenance requirements for system components such as regulators, valves, and indicators. R20 Examine the potential ammonia concentration in the event of a release at the expansion joint in the Off-Site Consequence Analysis (maximum flow rate is 45 gallons per hour of aqueous ammonia). R21 Depending on the results of R19, consider the feasibility of wiring the electrical so that the operator can tell in the control room which ammonia detector has been activated. R22 Update the emergency response plan to include a leak on the 5th floor and to incorporate the results of R19 and R20. Once the ammonia flow is stopped, the operator can examine the equipment for air flow out of the expansion joint. R23 Following implementation of R20 and R21, consider changing the response plan so that the operator does not use the elevator for responding to an ammonia release. R24 Determine the maintenance requirements and/or life expectancy of the expansion joints. R25 Review the air intake location of the control room to ensure that it is a safe location for the operators during a release. R26 Reevaluate the need for SCBAs (confined space entry). Based on this evaluation, consider implementing an escape mask policy, update the Respiratory Protection Program, and/or institute the training requiremen ts (annual, fit tests, physicals) and maintenance requirements (monthly inspection, etc.) associated with maintaining SCBAs. R27 Consider purchasing an ammonia detector (hand held monitor, dreager, etc.) to document that operators are not responding to releases in excess of the IDLH (300 ppm). R28 Verify that the emergency response plan includes emergency escape procedures and route assignments for all employees. R29 Verify that the floor plans or workplace maps that clearly show escape routes and refuge areas are available to employees. R30 Verify that the there is a clear chain of command for emergencies, and a responsible person and a backup identified to coordinate emergency activities. R31 Verify that the emergency response plan details procedures for accounting for all employees after the evacuation is completed, with a responsible person to report any missing personnel. R32 Post emergency telephone numbers on or near telephones and at other conspicuous lo cations. R33 Verify that the emergency response plan includes the names or regular job titles of people who must be notified in case of an emergency and who may be contacted for further information or explanation of duties. R34 Examine the existing alarms (and public address system) to ensure that the Plant has an adequate and distinctive alarm system that all people in the facility can hear or see. R35 Verify that all employees have been trained in evacuation plans, alarm systems, reporting procedures, shutdown procedures, and types of potential emergencies. R36 Implement a policy to hold regular evacuation exercises for the entire workforce. R37 Use the checklist included in Appendix C of the HAZOP report to review the Emergency Response Plan annually. R38 In developing the radio check-in policy, consider having a timer in the control room to alert the control room operator. R39 Consider developing a Plant labeling program so that all pipes are labeled to identify contents and direction of flow. Identify a person/title responsible for upkeep of the labels. R40 Review Cal-OSHA's means of egress and exit sign requirements (8 CCR 3215 & 3216). R41 Prepare a complete set of written procedures including startup, shutdown, normal operations, and emergency operations. R42 Operators should use the draft operating procedures to ensure their accuracy. Review and certify the procedures annually. |