Wamsutter Stabilization Facility - Executive Summary |
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Executive Summary ACCIDENTAL RELEASE PREVENTION AND RESPONSE POLICIES The Wamsutter Stabilization Facility has a long-standing commitment to worker and public safety. This commitment is demonstrated by the resources invested in accident prevention, such as training personnel and considering safety in the design, installation, operation, and maintenance of our processes. Our policy is to implement reasonable controls to prevent foreseeable releases of regulated substances. However, if a release does occur, trained personnel will respond to control and contain the release. DESCRIPTION OF THE STATIONARY SOURCE AND REGULATED SUBSTANCES The Wamsutter Stabilization Facility, located near Wamsutter, Wyoming, operates a condensate stabilization process to produce petroleum products, including natural gas, natural gas liquids, and stabilized condensate from the unstabilized condensate liquid inlet stream. The mixed NGL stream is recovered from the overhead of the condensate stabilizat ion process. The only regulated flammable at the Wamsutter Stabilization Facility is the mixed NGL product produced from the condensate stabilization process. This mixed NGL product contains regulated flammables from methane through pentane and these compounds are present as components of the mixed stream. There are no regulated toxic compounds at the Wamsutter Stabilization Facility and hydrogen sulfide is not present in the facility in any concentrations or volumes subject to regulation or of concern. Due to being a field production facility upstream of a "gas plant" as defined in the regulations, the other hydrocarbon streams at the facility are not subject to the RMP rule. However, the scenario of a catastrophic failure of the NGL storage bullet represents the greatest off-site impact distance potential from any portion of this facility. All of the covered processes in the facility are designated as "Program 1" under this Risk Management Plan and handled accordingly. OFFSITE CONSEQUENCE ANALYSIS RESULTS Toxic Release Scenarios There are no regulated toxic compounds or processes at the Wamsutter Stabilization Facility in a mass great enough to trigger RMP coverage. Flammable Release Scenarios The WCS associated with the release of flammable substances at the Wamsutter Stabilization Facility is the release of the full inventory of the NGL storage bullet followed by a vapor cloud explosion. This is an instantaneous release of 216,186 pounds of the mixed NGL product although butane was chosen as the flammable component for modeling purposes due to restrictions on the models ability to handle mixtures. Butane was chosen as the constituent with the greatest radius of off-site impact. The modeling of off-site impacts was done using the TNO Multi-Energy model incorporated into the BP Cirrus modeling system and was done using worst case meteorological conditions of F stability and 1.5 meters/sec. wind speed. The maximum distance to the 1-psi overpressure endpoint for the WCS is 0.24 miles with the assumption of the storage bullet being 100% liquid full. In reality, the storage bullet is operated in the range of 30-60% full so this scenario represents a very conservative worst case. Although we have numerous controls to prevent such releases and to manage their consequences. no credit for control or mitigation measures was taken into account in evaluating this WCS. The ARS for flammable substances was chosen to be the release of the full inventory of the NGL storage bullet at 50% liquid full in an instantaneous release followed by a vapor cloud explosion. A conservative assumption that the entire inventory was butane was made due to the models inability to handle mixtures in the alternative scenario mode. Butane was chosen as the substance which has the greatest overpressure zone associated with this type of release. The EPAs RMP-Comp model was used to determine the maximum distance to the 1-psi overpressure endpoint. Meteor ological conditions used were the same worst case conditions used for the worst case scenario. The maximum distance to the 1-psi overpressure endpoint for this ARS is 0.19 miles. No control or mitigation activities were considered in evaluating this scenario. CHEMICAL-SPECIFIC PREVENTION STEPS The processes at the Wamsutter Stabilization Facility have hazards that must be managed to ensure continued safe operation. The following is a description of existing safety features applicable to prevention of accidental releases of regulated substances in the facility. Specialized Safety Features The Wamsutter Stabilization Facility has safety features on many units to help (1) contain/control a release, (2) quickly detect a release, and (3) reduce the consequences of (mitigate) a release. The following types of safety features are used in the covered processes: Release Detection 1. Process area detectors and process perimeter monitors with alarms. Release Containment/Control 1. Process relief valves that discharge to a flare to capture and incinerate episodic releases. 2. Valves to permit isolation of the process and to prevent backflow. 3. Automated shutdown systems for specific process parameters. 4. Curbing or diking to contain liquid releases. 5. Redundant equipment and instrumentation (e.g., uninterruptible power supply for process control system, emergency air supply, backup pumps). 6. Atmospheric relief devices. Release Mitigation 1. Fire suppression and extinguishing systems. 2. Trained emergency response personnel. 3. Personal protective equipment. FIVE-YEAR ACCIDENT HISTORY The Wamsutter Stabilization Facility has an excellent record of accident prevention over the past 5 years. There have been no incidents with off-site impacts during the previous 5 years. EMERGENCY RESPONSE PROGRAM INFORMATION The Wamsutter Stabilization Facility maintains a written emergency response program, which is in place to protect worker and p ublic safety as well as the environment. The program consists of procedures for responding to a release of a regulated substance, including the possibility of a fire or explosion if a flammable substance is accidentally released. The procedures address all aspects of emergency response, including proper first aid and medical treatment for exposures, evacuation plans and accounting for personnel after an evacuation, notification of local emergency response agencies and the public if a release occurs, and post incident cleanup and decontamination requirements. In addition, the plant has procedures that address maintenance, inspection, and testing of emergency response equipment, as well as instructions that address the use of emergency response equipment. Employees receive training in these procedures as necessary to perform their specific emergency response duties. The emergency response program is updated when necessary based on modifications made to gas plant processes or other W amsutter Stabilization Facility facilities. The emergency response program changes are administered through the MOC process, which includes informing and/or training affected personnel in the changes. The overall emergency response program for the Wamsutter Stabilization Facility is coordinated with the Carbon County Emergency Planning Committee (LEPC). This coordination includes periodic meetings of the committee, which includes local emergency response officials, local government officials, and industry representatives. The Wamsutter Stabilization Facility has around-the-clock communications capability with appropriate LEPC officials and emergency response organizations (e.g., fire department). This provides a means of notifying the public of an incident, if necessary, as well as facilitating quick response to an incident. PLANNED CHANGES TO IMPROVE SAFETY The Wamsutter Stabilization Facility resolves all audit findings, some of which result in modifications to the process. The following types of changes are planned over the next few years in response to safety audit findings: 7 Update process safety information 7 Update emergency response procedures |