Tessenderlo Kerley, Inc. - Sahuarita Facility - Executive Summary

| Accident History | Chemicals | Emergency Response | Registration | Source | Executive Summary |

1.0    Sahuarita Facility Risk Management Plan:  Executive Summary 
The Sahuarita Facility (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 the facility's processes.  The Tessenderlo Kerley, Inc. (Tessenderlo Kerley) 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. 
Tessenderlo Kerley owns and operates the Sahuarita Facility located in Sahuarita, Arizona.  The facility produces liquid xanthate and dry xanthate.  The liquid xanthate production is a batch process.  The mixture is circulated and agitated until laboratory analys 
is confirms the reaction is complete.  The finished xanthate solution is filtered and pumped to storage. 
The products made in the liquid plant are as follows: 
Sodium isopropyl xanthate (SIPX) 
Potassium amyl xanthate (PAX) 
Sodium iso-butyl xanthate (SIBX) 
Sodium n-butyl xanthate (SNBX) 
Sodium ethyl xanthate (SEX) 
Carbon disulfide is common to all of the reactions.  Sodium isopropyl xanthate (SIPX) is the product generated by the dry xanthate plant process.  Since this reaction is exothermic and produces a solid, pentane is introduced to form a pumpable xanthate slurry and also to absorb the heat of reaction.  After drying, the solid pellets are then weighed into fiber-board or steel drums for storage or shipment. 
The Facility was evaluated to determine if any regulated flammable or toxic substances exceeded the threshold quantity.  Based on process knowledge, Tessenderlo Kerley identified one listed flammable substance and one toxic regulated substance kept on site.  The chemicals,  
largest quantities on site, and associated threshold quantity is presented in Table 1. 
Largest Quantity of Regulated Substances 
Regulated Substances             Largest Quantity On Site (lbs)               Threshold Quantity (lbs) 
Pentane                                                112,000                                                  10,000 
Carbon Disulfide                                  230,000                                                   20,000 
Pentane is stored in two pressurized 10,000-gallon horizontal steel tanks.  The tanks contain pressure relief valves, but no vents to the atmosphere. 
Carbon disulfide is stored in two pressurized horizontal steel tanks each with a capacity of 10,500 gallons.  The tanks are elevated and sit over a below-grade, concrete-lined water vessel.  A pressure relief valve protects the tanks.  In the event of a tank rupture, the carbon disulfide, which is heavier than water, would sink to the bottom of the pit displacing the  
water.  The carbon disulfide could then be recovered back into a tank. 
Worst-Case Scenarios 
The listed substances, which are stored above threshold quantities at the Sahuarita Facility, are pentane and carbon disulfide.  Based on worst-case analysis, the distances to the endpoints exceed the distances to public receptors.  In addition, the Facility is subject to OSHA PSM.  Therefore, the Sahuarita Facility contains a Program 3 process under the Accidental Release Prevention (ARP) program. 
Flammable Substances 
The Facility has one flammable substance above the threshold quantity, which is pentane.  The distance to the endpoint (1 psi overpressure) for the worst-case release of the above threshold quantity flammable substance using the EPA equations and constant is presented in Table 2.  A release of 56,000 lbs of pentane is the worst-case flammable release with a 0.30-mile distance to the endpoint. 
Toxic Substances 
The endpoint for a worst-case release of a toxic substance is base 
d on the Emergency Response Planning Guideline level 2 (ERPG-2) developed for each substance by the American Industrial Hygiene Association. The ARP Program requirement for toxics, in a worst-case scenario, assumes total quantity released in ten minutes.  
The distance to the endpoint for the worst-case release of the above threshold quantity toxic substance using the EPA equations is presented in Table 2.  A release of 115,000 lbs of carbon disulfide is the worst-case toxic release with a 1.43-mile distance to the endpoint. 
Distance to Endpoints for Worst-Case Scenarios 
Chemical Name               Toxic Endpoint ERPG-2         Distance to Endpoint (miles) 
Pentane                            1 psi overpressure                             0.30 
Carbon Disulfide                     0.16 mg/L                                      1.43 
Alternative Releases Scenarios 
Alternative release scenarios are those that are more likely to occur than the worst-case release scenario. Alterna 
tive release scenarios for flammable substances should have the potential to cause substantial damage, including onsite damage.  Alternative release scenarios for toxic substances should be those that lead to concentrations above the toxic endpoints beyond the facility's fenceline. The following conditions are considered for alternative release scenarios: 
7 Release rate dependent upon the scenario; and, 
7 Consideration of active and passive mitigation systems. 
Flammable Substances 
The Sahuarita Facility has one flammable substance held above the threshold quantity.  A hypothetical, but likely to occur release scenario has been identified for the flammable substance above the threshold quantity.  This scenario involves a break in a 3-inch pentane hose utilized for unloading material from trucks into the onsite tankage.  This leak would be projected to occur for a total of 5 minutes.  The distance to the endpoint for an explosion of this material is 0.12 miles. 
Toxic Substances 
alternative release scenario for each toxic substance is required under the ARP program.  A hypothetical, but likely to occur, release scenario has been identified for the toxic substance above threshold quantity. This scenario involves overfilling of the carbon disulfide tank (during railcar unloading) for a 5 minute period.  The alternative release resulted in a 0.48-mile distance to the 0.16 mg/L ERPG-2 endpoint for carbon disulfide. 
The distances to the endpoints for the alternative releases are presented in Table 3.   
Table 3 
Distance to Endpoints for Alternative-Case Scenarios 
Chemical Name                                 Pentane                       Carbon Disulfide 
Storage Capacity (pounds)             12,141                                    2,500 
Toxic Endpoint ERPG-2                  1 psi overpressure                   0.16 mg/L 
Distance to Endpoint (miles)                  0.12                                     0.48 
The following 
is a summary of the accident prevention program in place at the Sahuarita Facility.  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.  Therefore, this summary addresses each of the OSHA PSM elements and describes the management system in place to implement the accident prevention program.  The facility is in the process of reviewing the accident prevention program and is in various stages of implementing changes to improve work place safety. 
Employee Participation 
Active employee participation and involvement in the development and implementation of the Facility'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 Facility strongly promotes employee involvement in safety issues through existing programs.  These programs include Hazardous Materials Team (HazMat Teams), 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 Sahuarita Facility 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 questio 
ns, 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 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 to be readily available to all employees. 
A variety of technical documents are to be kept 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).   
Numerous technical documents are to be maintained 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 proposed process and facility changes to ensure that safety features in the process are not compromised. 
Process Hazard Analysis (PHA) 
There is 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 Facility primarily uses the hazard and operabilit 
y (HAZOP) and What-if/Checklist method analysis techniques to perform these evaluations.  However, as situations warrant, the Facility will use other inductive techniques such as what if/checklist.  The analyses are conducted using a team of people who have operating and maintenance experience as well as engineering expertise.  PHA team members include the process/project engineer responsible for the process/project; plant manager or knowledgeable plant person; person knowledgeable in methods of hazard analysis; and others with particular expertise (operators).  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  
matrix assigned by the PHA team.  The matrix is based on severity (criticality) and probability (frequency).  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 PHA team 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 recommended order of analysis will be based upon the following criteria:  
1. age of process;  
2. extent of process hazards;  
3. number of affected employees; and  
4. operating history of the process.   
The results and findings fr 
om these updates are documented and retained.  Once again, the team findings are forwarded to management for consideration, and the final resolution of the findings is documented and retained. 
Operating Procedures 
Written procedures are to be maintained that address various modes of process operations, such as the following:  
1. initial startup;  
2. normal operations;  
3. temporary operations;  
4. emergency shutdown;  
5. emergency operations;  
6. normal shutdown;  
7. startup following a turnaround; and  
8. start up after emergency shutdown.   
These procedures provide guidance for experienced operators and also provide the basis for training new operators.  
Operating procedures are to be periodically reviewed and will be periodically certified as current and accurate.  The review is to assure that the procedures reflect current operating practice, include changes from process technology changes, chemical changes, equipment changes, and changes to facilities.  The review and certifi 
cation 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 completing the stated procedures.  The specific instructions include the applicable safety precautions and appropriate information on safety implications. 
In addition to training on operating procedures, there is to be a comprehensive training program for all employees involved in operating the process.  New employees are to receive basic training in process operations and procedures. In addition, all operators are to periodically receive refresher training on the operating p 
rocedures to ensure that their skills and knowledge are maintained at acceptable level.  This refresher training is to be conducted at least every three years.  The appropriate frequency of training is to be based on management in consultation with the employees involved in operating the particular process.  All of this training is to be documented for each operator including the means used to verify that the operator understood the training. 
The Sahuarita Facility uses contractors during periods of increased maintenance or construction activities.  Because some contractors work on or near process equipment, there are to be procedures in place to ensure that contractors do as follows:  
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; 
6. inform plant personnel of any hazards th 
at they find during their work period. 
This is to be accomplished by providing contractors with an orientation session that covers the following: 
1. a process overview; 
2. information about safety and health hazards including known or potential fire,   explosion, or toxic release hazards; 
3. emergency response plan requirements;  
4. safe work practices must be developed and implemented regarding control of entrance, presence and exit of contract personnel prior to beginning their  work. 
In addition, contractor safety programs and performance during the selection of a contractor are to be evaluated.  Contract employee injury and illness log should be maintained.  Plant personnel are to periodically monitor contract performance to ensure that contractors are fulfilling their safety obligations. 
Pre-startup Safety Review (PSSR) 
A PSSR should be conducted on any new facility or facility modification that requires a change in process safety information.  The purpose of the PSSR is to e 
nsure that safety features, procedures, personnel, and equipment are appropriately prepared for startup prior to placing the equipment and highly hazardous chemicals 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.  The PSSR also ensures that procedures (safety, operating, maintenance, and emergency) are in place an adequate.  
Mechanical Integrity 
Well established practices and procedures for maintaining process equipment should be kept.  The basic aspects of this program are to include the following: 
1. training; 
2. developing written procedures; 
3. performing inspections and tests consistent with good engineering practices; 
4. correcting equipment deficienc 
ies outside acceptable PSI limits; 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 the following:   
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 the mechanical integrity program is quality assurance.  Quality assurance measures are to be incorporated into equipment purchases and repairs.  This helps ensure that new equipment is suitable for its intended use and proper materials and spare parts are used when repairs are made. 
Safe Work Practices 
Work practices are to be reviewed during construction of new processes or equipment to ensure revisions are suitable for the process application.  Checks and inspections are to be performed  
to assure that installation is consistent with design specifications and manufacturer's instructions suitable for the particular application.   
The Facility has long standing safe work practices in place to help ensure worker and process safety.  Examples of these include the following: 
1. control of the entry/presence/exit of support personnel; 
2. a lockout/tagout procedure to ensure isolation of energy sources for equipment undergoing maintenance; 
3. a procedure for safe removal of hazardous and toxic 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 
There is a comprehensive system of wri 
tten procedures to manage changes to all covered processes.  This system requires that changes to items such as process chemicals, process equipment, technology (including process operating conditions), procedures, impact to safety and health and other facility changes be properly reviewed and authorized before being implemented.  Prior to changes being made, they are reviewed to ensure that adequate controls are in place to manage any new hazards and verification 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, including contractor employees, are provided any necessary training on the change. 
Incident Investigation 
The Facility promptly investigates (within 48 hours) all incidents that resulted in or reasonably could have resulted in, a fire/explosion, toxic gas rel 
ease, 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 reports are maintained for five years.   
An investigation team is established to investigate each process incident.  The team will consist of members involved in the incident including at least one person knowledgeable in the process involved; a contract employee (if the incident involved the work of a contractor); and other persons with appropriate knowledge and experience to thoroughly investigate and analyze the incident.  The investigation team documents its findings in a report.  The report includes dates of incident and of investigation, description of incident, factors contributing to the incident, and develops recommendation to prevent a recurrence, and forwards these results to the business management team for resolution.   
mpliance Audits 
To help ensure that the accident prevention program is functioning properly, the Sahuarita Facility 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 three years.  Both hourly and staff personnel participate as audit team members with at least one person knowledgeable in the audit techniques.   
The audit team develops findings in a report that is forwarded to plant management for resolution.  Corrective actions taken in response to the audit team's findings are tracked and documented until they are complete.  The final resolution of each finding is documented, and the appropriate enhancements to the prevention program are implemented.  The two most recent compliance audit reports are retained. 
Chemical Specific Prevention Steps 
The processes at the Sahuarita Facility have hazards that must be managed to ensure continued saf 
e operation.  The following is a description of existing safety features applicable to prevention of accidental releases of regulated substances in the facility. 
Universal Prevention Activities 
The accident prevention program summarized previously is applied to the RMP-covered process at the Sahuarita Facility.  Collectively, these prevention program activities help prevent potential accident scenarios that could be caused by equipment failures and human errors. 
Specialized Safety Features 
The Facility has safety features on many units to help with the following:  (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 RMP covered process: 
Release Detection 
1. Sensors with audible alarms are located at the loading rack, reactor, and storage tank areas. 
Release Containment/Control 
1. Pressure relief valves on storage tanks designed to relieve at 60 or 150 psi for 
pentane and carbon disulfide respectively. 
2. Key manual valves are chained and padlocked in their critical (open/closed) position. 
3. Automated shutdown systems activated by motor failure. 
4. High level and high pressure indicates with alarms. 
5. Derailers and chock blocks to prevent rail car movement for carbon disulfide railcars. 
Release Mitigation 
1. Standard operating procedures that control, isolate, and terminate leaks. 
2. Personnel trained in emergency procedures. 
3. Personal protective equipment (e.g., escape respirator, self-contained breathing apparatus, and supplied air breathing apparatus), 
4. Ventilate contaminated areas. 
Five Year Accident History 
The Sahuarita Facility has an excellent record of accident prevention over the past five years.  There have been no incidents involving a release of isopropyl pentane or carbon disulfide, which had offsite effects. 
Emergency Procedure Information 
The Facility maintains a written emergency procedure, which is in place to p 
rotect worker and public safety as well as the environment.  The procedures account for the possibility of a toxic substance being accidentally released, as well as for the possibility of a fire or explosion.  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 the Facility.  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 Facility is coordinated with the local fire and police.  The Facility has around-the-clock communications capability with appropriate officials and emergency response organizations (e.g., fire department).  This provides a means of notifying the public of an incide 
nt, if necessary, as well as facilitating quick response to an incident.  In addition, the Facility conducts periodic emergency drills that involve emergency response organizations, and the Facility provides periodic refresher training to local emergency responders regarding the hazards of regulated substances in the plant.
Click to return to beginning