Glasscock Hollow Field Production Facility - Executive Summary |
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Executive Summary ACCIDENTAL RELEASE PREVENTION AND RESPONSE POLICIES The Glasscock Hollow Field Production 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 Glasscock Hollow Field Production Facility, located near Evanston, Wyoming, operates typical field separation and compression processes to separate condensate and water from the natural gas stream and compress the gas for transshipment to further processing at other facilities. A mixed "compressor liquids" NGL and condensate stream is recovered from the liquids knocked out during compression of the gas and stored as a mixed NGL/condensate mixture in a pressurized storage bullet. The only regulated flammable at the Glasscock Hollow Field Production Facility is the mixed NGL/condensate product produced from the compression of the gas. This mixed hydrocarbon 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 Glasscock Hollow Field Production 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 por tion 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 Glasscock Hollow Field Production Facility in a mass great enough to trigger RMP coverage. Flammable Release Scenarios The WCS associated with the release of flammable substances at the Glasscock Hollow Field Production Facility is the release of the full inventory of the storage bullet followed by a vapor cloud explosion (VCE). This is an instantaneous release of 107,015 pounds of the mixed NGL product, followed by vaporization and detonation in a VCE. The modeling of off-site impacts was done using EPAs RMP-Comp model with 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 0.4 miles with the assumpt ion of the storage bullet being 100% liquid full. 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 complete severing of a 2" process pipe on the bottom (liquid portion) of the storage bullet followed by a vapor cloud explosion. A conservative assumption that the entire inventory was propane was made due to the models inability to handle mixtures in the alternative scenario mode. Propane 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 release rate of 7380 lbs/min and the maximum distance to the 1-psi overpressure endpoint. Meteorological conditions used were those incorporated into the model as defaults for alternative scenario evaluation (D stability and 3.0 meters/sec wind speed). The release was assumed to persist for 14 minutes duration at the initial flow rate which is the time necessary to release the entire vessel contents through the 2 inch pipe. The maximum distance to the 1-psi overpressure endpoint for this ARS is 0.2 miles. No control or mitigation activities were considered in evaluating this scenario. CHEMICAL-SPECIFIC PREVENTION STEPS The processes at the Glasscock Hollow Field Production 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 Glasscock Hollow Field Production 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 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., backup pumps). 6. Atmospheric relief devices. 7. Process interlocks. Release Mitigation 1. Trained emergency response personnel. 2. Personal protective equipment. FIVE-YEAR ACCIDENT HISTORY The Glasscock Hollow Field Production 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 Glasscock Hollow Field Production Facility maintains a written emergency response program, which is in place to protect worker and public 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 Glasscock Hol low Field Production 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 Glasscock Hollow Field Production Facility is coordinated with the Uinta County Local 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 Glasscock Hollow Field Production 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 modifi cations to the process. The following types of changes are planned over the next few years in response to safety audit findings: 7 Update emergency response procedures 7 Inspect relief valves 7 Review operating procedures |