North Terrebonne Gas Plant - Executive Summary

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North Terrebonne Gas Plant Risk Management Plan:  Executive Summary 
The North Terrebonne Gas Plant 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 facility's processes.  The Shell Western E&P Inc. (SWEPI) policy is to implement reasonable controls to prevent foreseeable releases of substances. However, if a release does occur, trained personnel will respond to, control, and contain the release. 
SWEPI operates the North Terrebonne Gas Plant located in Terrebonne Parish, Louisiana.  Tejas Gas Processing, LLC is the owner of this facility.  The North Terrebonne Gas Plant accepts gas and condensate from natural reservoirs via pipeline.  Residue gas and extracted hydrocarbon 
liquids are removed from the plant by pipeline systems. 
The North Terrebonne Gas Plant was evaluated to determine if any regulated flammable or toxic substances exceeded the threshold quantity.  Based on process knowledge, SWEPI identified the regulated substances and quantities kept on site.   
Listed flammable substances which are stored above threshold quantities at the North Terrebonne Gas Plant are rich/lean oil, raw make, natural gas, sponge oil, condensate and propane.  However, SWEPI has determined that condensate has an NFPA flammability hazard rating of 1, which exempts this mixture from threshold determination.  Based on worst-case analysis, the distance to the endpoint exceeds the distance to public receptors.  In addition, the North Terrebonne Gas Plant is subject to OSHA PSM.  Therefore, the North Terrebonne Gas Plant is classified as a Program 3 process under the ARP program. 
Flammable Substances - Worst-Case Scenario 
The endpoi 
nt for worst-case release of flammable substances is 1 psi overpressure (i.e., 15.7 psia), resulting from a vapor cloud explosion. The ARP Program requirement for flammables assumes an instantaneous release and vapor cloud explosion.  A yield factor of 10 percent of the available energy released in the explosion shall be used to determine the distance to the explosion endpoint.  Since the worst-case release scenario for a flammable substance is based on the assumption that the entire quantity of the substance forms a vapor cloud, passive mitigation systems are not applicable.  Raw make is the worst-case flammable release with a 0.66-mile distance to the endpoint. 
Flammable Substances - Alternative-Case Scenario 
A single alternative release scenario for all flammable substances is required under the ARP program.  A hypothetical, but likely to occur, release scenario has been identified for lean oil as follows.  The collapse of the lean oil surge drum (V-1125) causes this vessel to emp 
ty contents which will vaporize and may ignite in a vapor cloud explosion with an endpoint of 1 psi overpressure.  The alternative-case release of lean oil resulted in a 0.43-mile distance to the 1 psi overpressure endpoint. 
Toxic Substances 
The North Terrebonne Gas Plant does not have any toxic substances held above the threshold quantity.  Therefore, analysis of worst-case or alternative-case release scenarios for toxic substances is not required. 
The following is a summary of the of the accident prevention program in place at the North Terrebonne Gas Plant.  Because the processes at the plant that are regulated by the Environmental Protection Agency's (EPA's) risk management program (RMP) regulation are also subject to the Occupational Safety and Health Administration's (OSHA's) process safety management (PSM) standard, this summary addresses each of the OSHA PSM elements and describes the management system in place to implement the accident prev 
ention program. 
Employee Participation 
Active employee participation and involvement in the development and implementation of the North Terrebonne Gas Plant's PSM program is an important step toward achieving the objective to prevent or minimize the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals.  Employee involvement will help to ensure that all perspectives regarding PSM are considered, and that the best ideas are implemented.  Open communications are encouraged between supervisors and employees regarding all safety and health issues. 
The North Terrebonne Gas Plant strongly promotes employee involvement in safety issues through existing programs.  These programs include Unit Safety Teams (which are made up of a cross section of employees and supervision), regularly scheduled safety meetings, tail-gate safety meetings, Hazard Communication, Safety Suggestion Forms, "near-miss" reporting, and special training programs (emergency response  
training, first aid, etc.).  
The North Terrebonne Gas Plant actively seeks employee involvement in the development and conduct of all accident prevention activities through the appropriate existing safety programs.  Accident prevention is discussed at the regularly scheduled safety meetings and/or during special training sessions if necessary.  Employees are encouraged to discuss accident prevention with their supervisors if they have questions, comments, or suggestions.   
Process Safety Information 
Complete and accurate written process safety information (PSI) concerning process chemicals, process technology, and process equipment is essential to an effective PSM and RMP programs and to completing and maintaining a process hazard analysis (PHA).  The PSI will be useful to the operators; the team performing the PHA; those in charge of training; contractors; those conducting pre-startup safety reviews; and those in charge of updating the emergency preparedness plans.  Process Safety  
Information is readily available to all employees. 
The North Terrebonne Gas Plant keeps a variety of technical documents that are used to help maintain safe operation of the process.  These documents address chemical properties and associated hazards, limits for key process parameters and specific chemical inventories, and equipment design basis/configuration information. 
Chemical-specific information, including exposure hazards and emergency response/ exposure treatment considerations, is provided in material safety data sheets (MSDSs).   
The gas plant also maintains numerous technical documents that provide information about the design and construction of process equipment.  This information includes materials of construction, design pressure and temperature ratings, and electrical rating of equipment. This information, in combination with written procedures and trained personnel, provides a basis for establishing inspection and maintenance activities, as well as for evaluating pr 
oposed process and facility changes to ensure that safety features in the process are not compromised. 
Process Hazard Analysis (PHA) 
The North Terrebonne Gas Plant has a comprehensive program to help ensure that hazards associated with the various processes are identified and controlled.  Within this program, each process is systematically examined to identify hazards and ensure that adequate controls are in place to manage these hazards. 
The North Terrebonne Gas Plant primarily uses the hazard and operability (HAZOP) and What-if/Checklist method analysis technique to perform these evaluations.  The analyses are conducted using a team of people who have operating and maintenance experience as well as engineering expertise. This team identifies and evaluates hazards of the process as well as accident prevention and mitigation measures, and the team makes suggestions for additional prevention and/or mitigation measures when the team believes such measures are necessary.  
The PHA team 
findings are forwarded to local and corporate management for resolution. Implementation of mitigation options in response to PHA findings is based on a relative risk ranking assigned by the PHA team.  This ranking helps ensure that potential accident scenarios assigned the highest risk receive immediate attention.  All approved mitigation options in response to PHA team findings are tracked until they are completed.  The final resolution of each finding is documented and retained. 
To help ensure that the process controls and/or process hazards do not eventually deviate significantly from the original design safety features, the periodically updates and revalidates the hazard analysis results.  These periodic reviews are conducted at least every 5 years and will be conducted at this frequency until the process is no longer operating.  The results and findings from these updates are documented and retained.  Once again, the team findings are forwarded to management for consideration, a 
nd the final resolution of the findings is documented and retained. 
Operating Procedures 
The North Terrebonne Gas Plant maintains written procedures that address various modes of process operations, such as; (1) startup (2) normal operations (3) temporary operations (4) emergency shutdown (5) normal shutdown, and (6) initial startup of a new process.  These procedures provide guidance for experienced operators and also provide the basis for training new operators.  Operating procedures are periodically reviewed and annually certified as current and accurate.  The review and certification process involves both operators and technical staff. 
The intent of the operating procedures is to provide workable, useful, and clearly written instructions for conducting operating activities.  To have effective operating procedures, the task and procedures directly and indirectly related to the covered process must be appropriate, clear, consistent, and most importantly, communicated to employees. 
 Operating procedures are specific instructions or details on what steps are taken or followed in caring out the stated procedures.  The specific instructions include the applicable safety precautions and appropriate information on safety implications. 
In addition to training on operating procedures the North Terrebonne Gas Plant has a comprehensive training program for all employees involved in operating the process.  New employees receive basic training in gas plant operations. In addition, all operators periodically receive refresher training on the operating procedures to ensure that their skills and knowledge are maintained at acceptable level.  This refresher training is conducted at least every 3 years.  All of this training is documented for each operator including the means used to verify that the operator understood the training. 
The North Terrebonne Gas Plant uses contractors to during periods of increased maintenance or construction activities.  Be 
cause some contractors work on or near process equipment, the gas plant has procedures in place to ensure that contractors (1) perform their work in a safe manner, (2) have appropriate knowledge and skills. (3) are aware of the hazards of their workplace, (4) understand what they should do in the event of an emergency, (5) understand and follow site specific safety rules, and (6) inform gas plant personnel of any hazards that they find during there work.  This is accomplished by providing contractors with an orientation session that covers (1) a process overview (2) information about safety and health hazards, (3) emergency response plan requirements, and (4) safe work practices prior to beginning their work.  In addition the North Terrebonne Gas Plant evaluates contractor safety programs and performance during the selection of a contractor.  Gas plant personnel periodically monitor contract performance to ensure that contractors are fulfilling their safety obligations. 
Pre-startup Sa 
fety Review 
The North Terrebonne Gas Plant conducts a PSSR on any new facility or facility modification that requires a change in process safety information.  The purpose of the PSSR is to ensure that safety features, procedures, personnel, and equipment are appropriately prepared for startup prior to placing the equipment into service.  This review provides one additional check to make sure construction is in accordance with design specification and that all-supporting systems are operationally ready.  The PSSR involves field verification of the construction and serves a quality assurance function by requiring verification that accident prevention program requirements are properly implemented. 
Mechanical Integrity 
The North Terrebonne Gas Plant has well established practices and procedures for maintaining process equipment.  The basic aspects of this program include (1) training, (2) developing written procedures, (3) performing inspections and tests, (4) correcting equipment defic 
iencies, when identified, and (5) applying quality assurance measures. In combination, these activities form a system that maintains the mechanical integrity of the process. 
Maintenance personnel receive training on (1) an overview of the process, (2) safety and health hazards, (3) applicable maintenance procedures, (4) emergency response plans, and (5) applicable safe work practices to help ensure that they can perform their jobs in a safe manner. 
Another integral part of mechanical integrity program is quality assurance.  The North Terrebonne Gas Plant incorporates quality assurance measures into equipment purchases and repairs.  This helps ensure that new equipment is suitable for its intended use and that proper materials and spare parts are used when repairs are made. 
Safe Work Practices 
The North Terrebonne Gas Plant has long standing safe work practices in place to help ensure worker and process safety.  Examples of these include (1) control of the entry/ presence/exit of su 
pport personnel, (2) a lockout/tagout procedure to ensure isolation of energy sources for equipment undergoing maintenance, (3) a procedure for safe removal of hazardous substances before process piping and equipment is opened, (4) a permit and procedure to control spark-producing activities (i.e., hot work), and (5) a permit and procedure to ensure that adequate precautions are in place before entry into a confined space.  These procedures (and others), along with training of affected personnel, form a system to help ensure that operations and maintenance activities are performed safely. 
Management of Change 
The North Terrebonne Gas Plant has a comprehensive system to manage changes to all covered processes.  This system requires that changes to items such as process equipment, technology (including process operating conditions), procedures, and other facility changes be properly reviewed and authorized before being implemented. Changes are reviewed to (1) ensure that adequate contr 
ols are in place to manage any new hazards and (2) verify that existing controls have not been compromised by the change.  Affected chemical hazard information, process operating limits, and equipment information, as well as procedures are updated to incorporate these changes.  In addition operating and maintenance personnel are provided any necessary training on the change. 
Incident Investigation 
The North Terrebonne Gas Plant promptly investigates all incidents that resulted in or reasonably could have resulted in, a fire/explosion, toxic gas release, major property damage, environmental loss, or personal injury.  The goal of each investigation is to gather the facts, determine the root cause, and develop corrective action to prevent the reoccurrence of the incident or a similar incident.  The investigation team documents its findings, develops recommendation to prevent a recurrence, and forwards these results to the business management team for resolution. 
Compliance Audits 
help ensure that the accident prevention program is functioning properly, the North Terrebonne Gas Plant periodically conducts an audit to determine whether the procedures and practices required by the accident prevention program are being implemented.  Compliance audits are conducted at least every 3 years.  Both hourly and staff personnel participate as audit team members.  The audit team develops findings that are forwarded to North Terrebonne Gas Plant management for resolution.  Corrective actions taken in response to the audit team's findings are tracked until they are complete.  The final resolution of each finding is documented, and the two most recent audit reports are retained.   
The processes at the North Terrebonne Gas Plant 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 facilit 
Universal Prevention Activities 
The accident prevention program summarized previously is applied to all RMP-covered processes at the North Terrebonne Gas Plant.  Collectively, these prevention program activities help prevent potential accident scenarios that could be caused by equipment failures and human errors. 
Specialized Safety Features 
The North Terrebonne Gas Plant 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. Hydrocarbon 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 (manual or automated) 
3. Automated shutdown systems for specific process parameters (e.g., high  temperature) 
4. Curbing or diking to contain liquid release 

5. Redundant equipment and instrumentation (e.g., uninterruptible power supply for process control system, backup firewater pump) 
6. Atmospheric relief devices. 
Release Mitigation 
1. Fire suppression and extinguishing systems  
2. Deluge system for specific equipment 
3. Personnel trained in emergency procedures 
4. Personal protective equipment (e.g., chemical protective clothing, self-contained breathing apparatus) 
The North Terrebonne Gas Plant has an excellent record of accident prevention over the past 5 years. There has been one incident involving a release of lean oil, which had no off-site effects.  The incident was investigated very carefully to determine ways to prevent similar incidents from recurring.  The recommendations from the investigation were implemented.   
The North Terrebonne Gas Plant maintains a written emergency procedure, which is in place to protect worker and public safety as well as the environm 
ent.  The procedures are for the possibility of a fire or explosion if a flammable substance is accidentally released.  The procedures address notification of local emergency response agencies if a release occurs, and post incident cleanup and decontamination requirements.  Employees receive training in emergency procedures.  The emergency procedure is updated when necessary based on modifications made to North Terrebonne Gas Plant facilities.  The emergency procedure changes are administered through the Management of Change (MOC) process, which includes informing and/or training affected personnel in the changes. 
The overall emergency procedure program for the North Terrebonne Gas Plant is coordinated with the Terrebonne Parish, Louisiana, 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 North Terrebonne Gas Plant  
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.  In addition to periodic LEPC meetings, the North Terrebonne Gas Plant conducts periodic emergency drills that involve the LEPC and emergency response organizations, and the North Terrebonne Gas Plant provides periodic refresher training to local emergency responders regarding the hazards of regulated substances in the plant.
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