South Point Energy Center - Executive Summary |
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Introduction Calpine Corporation's South Point Energy Center uses anhydrous ammonia as a necessary part of reducing the emissions of nitrogen oxides to the atmosphere. Storing a large quantity of ammonia can be a hazard if it is not handled properly. As the company responsible for operating South Point Energy Center, Calpine Corporation take its safety obligations in storing and using ammonia as seriously as we take controlling emissions from the power plant. The following document describes what could happen if there were to be an accident, the steps we take every day to ensure a safely operating plant, and what to do in the event of an emergency. Accidental Release Prevention and Emergency Response Policies The South Point Energy Center accidental release prevention policy involves a unified approach that integrates proven technology, staff training on operation and maintenance practices, and tested management system practices. All applicable procedures of the State of Arizona and U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to, including key elements such as training, systems management, and emergency response procedures. This document complies with the EPA Risk Management Program under Section 112 (r) of the Clean Air Act (CAA) Amendments of 1990, 40 Code of Federal Regulations (CFR) Part 68. This document summarizes our existing health and safety programs, our internal management response procedures, and ongoing actions that are designed to prevent or minimize impacts of accidental releases of ammonia to the environment. South Point Energy Center has prepared an emergency action plan to handle any potential accidental releases. General Facility and Regulated Substances Information The South Point Energy Center is located at 3779 Courtwright Road, Mohave Valley, Arizona, in Mohave County. This power plant is located on a 320-acre property on the Fort Mojave Indian Reservation on the lower western slopes of the Black Mo untains. Havasu National Wildlife Refuge and the Topock Marsh lie approximately 1.2 miles south. South Point Energy Center is a natural gas fired 544 megawatt combined cycle power plant. Electricity generated by this facility is transported by lines owned by the Western Area Power Administration (WAPA). Power is delivered from the plant to the Topock substation off-site by two 230 kV transmission lines in order to wheel power to the WAPA distribution grid. The electricity will be sold under a variety of short-, mid-, and long-term contracts into the Arizona, California, and Nevada markets. The facility currently stores anhydrous ammonia, a regulated toxic substance under RMP regulations, in two 14,193 gallon (filled to 85 percent capacity) steel bulk storage tanks. Ammonia is used at the South Point Energy Center to reduce nitrogen oxides (NOx) created during the combustion of natural gas and exhausted from the two Combustion Turbine Generators (CTG) and Heat Recovery Steam Gene rators (HRSG) duct burners. Ammonia vapor is drawn from the top of the storage tank and diluted with air, and injected into the two Selective Catalytic Reduction (SCR) units to reduce the NOx emissions. The maximum quantity of anhydrous ammonia stored at South Point Energy Center exceeds the federal RMP specified threshold quantities of 10,000 lbs; thus, the facility is subject to federal RMP regulations. Relief Valves. Pressure relief valves are located throughout the process system to protect against excess pressure. All process related factory-set pressure relief valves are set to protect the safety of workers and the integrity of the equipment Piping from the storage tank is equipped with excess-flow valves to stop the flow from the bulk tank in event of emergency. Secondary Containment. The ammonia storage tanks and vaporizer are located inside a secondary containment area sufficient to contain 120% of the tank capacity. The dimension of the containment area is 43 feet by 46 feet by 39 inches high. Leak Detection. Two Chillgard RT leak detectors are provided for the system to perform ambient ammonia monitoring. These monitors provide a signal to the Control Room to manually activate the deluge systems when high levels of ammonia are detected. These sensors are located north and south of the secondary containment unit and set to alarm when an ammonia concentration of 200 ppm is detected in the air. Alarm System. The ammonia process is checked at least twice during every 12-hour shift as part of the normal rounds at South Point Energy Center. The storage tank is provided with local pressure indicator (in psig) and level indicators (in percent volume). The tank also has pressure safety valves, temperature gauges, and ammonia leak detectors. Tank level, temperature, and pressure indication is displayed locally and indication and alarms are displayed on the Control Room Distributed Control System (DCS). Emergency Shower and Eyewash. An emergenc y eyewash and shower are provided at the truck unloading station near the ammonia storage tank. Deluge System. A deluge water system, consisting of one spray monitor attached to a fire hydrant located west of the containment area, is provided to dissipate an ammonia vapor cloud in case of a leak. The system will be manually activated in the event of an ammonia leakage. Solenoid Shut-Off Valve. On each ammonia storage tank there is a solenoid shut-off valve. This is an electronically operated ball valve that is controlled by the DCS system to initiate valve closure in the event of a leak detected in the process piping. Site Security. The main gate, located on Courtwright Road on the south side of the plant, provides the primary access to South Point Energy Center. It is kept closed at all times and it equipped with a keypad, call box, and closed circuit camera so that the Control Room personnel may identify and grant access to visitors at the gate. A perimeter fence encloses the facility. There are two emergency exits gates; one is located north of the cooling tower, and the other is on the west side of the service water/firewater pond in the northwest corner of the property. Offsite Consequence Analysis Results The offsite consequence analysis includes consideration of two release scenarios, identified as "worst case" and "alternative" release scenarios. The worst-case release scenario requires that a release of the entire contents of the single largest vessel or pipe be evaluated for offsite impacts. Only passive or administrative controls can be considered under the worst-case release scenario. The worst-case release scenario for South Point Energy Center is the rupture of an ammonia bulk storage tank, resulting in a release of 63,698 pounds of ammonia over a 10-minute duration. In practice, this type of total release of a bulk tank would be unlikely to occur during the lifetime of the plant. The released liquid is assumed to quickly volatiliz e and disperse as a vapor cloud. The distance to the toxic endpoint was estimated using the Areal Location of Hazardous Atmospheres (ALOHA) model. The toxic endpoint was conservatively set by EPA to ensure that local emergency response planning takes into account the greatest possible impacted area surrounding the release point. The toxic endpoint selected by EPA was 200 ppm. All required EPA-model input parameters were included in completing this activity, including conservative meteorological conditions - Stability F class, wind speed of 1.5 meters per second, highest daily maximum temperature (128 degrees F), and average humidity (30 percent). The results of the dispersion modeling analysis for this worst-case release scenario indicate that this scenario has an impact to receptors offsite. An alternative release scenario for each regulated substance is also required. The alternative release scenario is a release scenario more likely to occur than the worst-case release scenari o. Unlike the worst-case release scenario, active controls can be considered in analyzing the impacts of an alternative release scenario. Active controls consist of mechanical, electrical, or human input. The alternative release scenarios used for ammonia was a small leak in the process piping (flange). The active mitigation provided by leak detectors was considered. The same modeling approach used was similar to the worst-case release scenario, except meteorological conditions were adjusted to more common conditions of Stability D Class, wind speed of 3.0 meters per second, average air temperature of 77 degrees F, and average humidity of 50 percent. The results of the dispersion modeling analysis for the alternative release scenario indicate that this scenario has a much smaller offsite impact. Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps South Point Energy Center is in compliance with Federal Process Safety Management (PSM) req uirements. Chemical-specific prevention steps include availability of self-contained escape breathing apparatus; awareness of the hazardous and toxic properties of anhydrous ammonia; the presence of ammonia detectors and alarms, and a deluge system to mitigate any releases. The South Point Energy Center accidental release prevention program is based on the following key elements: ? Detailed management system and clear levels of responsibilities and team member roles ? Comprehensive safety process information that is readily available to staff, emergency responders, and contractors ? Comprehensive preventive maintenance program ? A process hazard analysis of equipment and procedures with operation and maintenance staff participation and review ? Use of state-of-the-art process and safety equipment ? Use of accurate and effective operating procedures, written with operations and maintenance staff participation ? High level of training of operators and maintenance staff ? Implementatio n of an incident investigation, inspection, and auditing program using qualified staff Process and Chemical Safety Information Comprehensive chemical data have been assembled to include regulatory reporting and action thresholds, health hazards, and chemical exposure limitations, as well as detailed physical properties of each regulated substance. This information was compiled from numerous sources and is intended to be a one-stop source for the reader seeking data about these substances. This information includes ammonia background information, material safety data sheets (MSDS), and ammonia reaction chemistry. Equipment safety information has been compiled on the ammonia process, and specifications for the process are compiled in one place for easy reference. Details such as maximum intended inventory, safe upper and lower operating temperatures and pressures, and codes and standards used to design, build, and operate the processes are on file at the facility. We also have sche duled reviews of our risk management program and process safety management plan to update safety information if there is a major change that would make existing information inaccurate. Process Hazard Analysis In January 2001, a detailed process hazard analysis (PHA) was conducted with plant staff, engineering, and administrative staff for the regulated process. The team consisted of process operating and maintenance experts and process design engineers. The PHA technique used was What If Analysis/Checklist Method, one of EPA's recommended approaches. The PHA was led by a person knowledgeable on the type of process being reviewed. This review will be updated again within a 5-year period or whenever there is major change in the process. A list of actions to resolve any significant findings from the analysis was prepared, and staff is currently working to resolve this action item list. Staff will document completion of any action item. Operating Procedures South Point Energy Ce nter maintains up-to-date, accurate, written operating procedures that give clear instructions for the ammonia process. South Point Energy Center ensures effective operating practices by combining them with operating and maintenance training programs. Standard operating procedures (SOPs) provide system descriptions, specifications, equipment inspection requirements, and operating procedures for the ammonia system. Procedures include startup, shutdown, and normal, alternate, and emergency operation. Also included are maintenance and troubleshooting procedures, including consequences of deviation and steps to avoid or correct deviations. South Point Energy Center will update procedures whenever a change occurs that alters the steps needed to operate safely. Operating procedures will be developed and implemented prior to any new process equipment coming on line or a changed process starting up. Operations and Maintenance Training Program Each South Point Energy Center employee pre sently involved in operating or maintaining the ammonia process is trained in an overview of the process and applicable operating and maintenance procedures. Training helps employees understand the nature and cause of problems arising from operations involving ammonia, and increases employee awareness of hazards. South Point Energy Center's training program includes both initial and refresher training that covers: (1) a general overview of the processes, (2) the properties and hazards of the substances in the process, and (3) a detailed review of the process operating procedures and safe work practices. Oral reviews and written self-evaluations are used to verify that an employee understands the training material before the process work can be resumed. Training documentation includes: date of most recent review or revision to the training program, type of training required and the type of competency testing used to ensure staff understands the training. Ongoing employee training records are maintained. Contractors The South Point Energy Center has procedures and policies in place that ensure that only contractors with good safety programs are selected to perform work on and around the ammonia process. Contractors are properly informed of the hazards, access limitations to these process areas, and emergency response procedures, and are prepared to safely complete the work. The South Point Energy Center sets minimum contractor safety performance requirements for work in process areas, holds contractor safety briefings before allowing them near or in the process area, controls access to the process areas, and evaluates the contractor's performance. Pre-Startup Safety Review and Mechanical Integrity Program South Point Energy Center ensures that a pre-startup safety review is completed for any new regulated process at the plant, or for significant modifications to an existing covered process that requires a change in the process safety information. South Point Energy Center maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public, or the environment. We believe that this program is the primary line of defense against a release. Maintenance staff address equipment testing and inspection, preventative maintenance schedules, and personnel training of these procedures. Our mechanical integrity program includes the following: ? Written procedures for maintaining mechanical integrity through inspection and testing of process equipment, based on instructions of equipment vendors, industry codes, and prior operating experience ? Implementation of written procedures by performing inspections and tests on process equipment at specified intervals ? Training of maintenance personnel in safe work practices such as lockout/tagout, line or equipment opening, and avoidance and correction of unsafe conditions ? Procedures specifying training requirements for contract maintena nce employees, as well as requiring contractors to use plant-developed maintenance procedures for process areas Hot Work Permits and Management of Change South Point Energy Center requires employees and contractors to employ safe work practices when performing "hot work" in, on, or around the regulated processes. South Point Energy Center uses a comprehensive permitting and training program to ensure hot work is conducted safely. South Point Energy Center provides a system and approach to maintain and implement management of changes or modifications to equipment, procedures, chemicals, and processing conditions. This system allows our employees to identify and review safety hazards or provide additional safety, process, or chemical information before the proposed change is implemented. Internal Compliance Audits Internal compliance audits are conducted every three years to verify compliance with the programs and procedures contained in the RMP. South Point Energy Center assem bles an audit team that includes personnel knowledgeable in the Risk Management Program rule and in the regulatory process. This team evaluates whether the prevention program satisfies the requirements of the RMP rule and whether the prevention program is sufficient to help ensure safe operation. The results of the audit are documented, recommendations are resolved, and appropriate enhancements to the prevention program are implemented. Incident Investigation South Point Energy Center investigates all incidents that could reasonably have resulted in a serious injury to personnel, the public, or the environment, so that similar accidents can be prevented. South Point Energy Center trains employees to identify and report any incident that requires investigation. An investigation team is assembled and the investigation is initiated within 48 hours of any incident. The results of the investigation are documented, recommendations are resolved, and appropriate process enhancements are implemented. Information found during the investigation is reviewed by appropriate staff and is added to, or used to revise operating and maintenance procedures. Information from audits and any resulting changes in operating procedures are passed onto the training unit for their inclusion in existing training programs, if warranted, to prevent a future event. Five-Year Accident History Summary EPA RMP regulations require reporting the five-year accident history of the covered processes. The details of accidental releases are required for accidents that have caused at least one of the following: ? Onsite deaths, injuries, or significant property damage ? Known offsite deaths, injuries, property damage, environmental damage, evacuations, or sheltering in place South Point Energy Center is a new facility and has had no accidents involving ammonia. Emergency Response Program Summary South Point Energy Center has established a written emergency action program that is followed by th e employees to help safely control accidental releases of hazardous substances. This program has been coordinated (reviewed) by the Mohave Valley Fire Department, which is a member of the Local Emergency Response Planning Committee (LEPC). This program includes an emergency action and notification plan. Emergency operation and action procedures are also reviewed once per year. Planned Changes to Improve Safety During the process hazard analysis, several additional risk reduction measures were recommended to improve safety at South Point Energy Center. These measures included instituting an overhead work procedure to ensure material is not carried over the storage tank, preparing a preventive maintenance schedule for piping inspections, and confirming that the ammonia vendor has a preventive maintenance program for the delivery truck hoses. |