Cargill North American Corn Milling - Executive Summary

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Cargill Inc. owns and operates a wet corn milling facility in Blair, Nebraska which is subject to U.S. EPA regulations governing Accidental Release Prevention Requirements: Risk Management Programs (RMP) under Section 112(r) of the Clean Air Act (40 CFR Part 68).  This Risk Management Plan has been developed in accordance with the requirements specified under 40 CFR Part 68, Subpart G.  The Risk Management Plan certifies that Cargill Corn Milling Division has instituted a Risk Management Program at the Blair, Nebraska facility that is in compliance with U.S. EPA RMP requirements.  
The Risk Management Plan follows the format provided by the RMP Data Elements published by U.S. EPA.  In addition to identifying the applicable corporate policies and risk management systems, including comprehensive accident prevention and emergency response programs, the Risk Management Plan identifies a set of worst cas 
e and alternative release scenarios and the facility's five year accidental release history.  The Risk Management Plan also verifies that prevention, mitigation, and emergency response plans are appropriately designed to minimize risks to workers and the potentially affected public.   RMP Data Elements are included as part of this Risk Management Plan. 
1.1 Corporate Statement 
Cargill's policy is to conduct all business activities in a manner that protects the environment and the health and safety of our employees, contractors, customers and the public. 
Environment.  Cargill will comply with all applicable laws and regulations; promote waste reduction, resource and property conservation and environmental protection; and train employees to be knowledgeable about all environmental matters relevant to their work. 
Health and Safety.  Cargill will design, construct, maintain and operate facilities to protect human and physical resources; provide and require use of adequate protective equ 
ipment and measures, and insist that all work, however urgent, be done safely. 
Food and Product Safety.  Cargill will provide safe food, feed, and materials for people and animals by using production, storage and transportation facilities that ensure the safety of products; choose suppliers that meet our requirements for safe raw materials and ingredients; and provide employees the training and resources they need to meet their individual responsibilities. 
The Cargill Foods Corn Milling Division plant in Blair is designed, maintained and operated so as to minimize adverse impacts to its employees, local communities and the environment.  In order to insure the safe and effective response to an unlikely emergency in the workplace, the Blair plant coordinates its safety and emergency response program with the local community's emergency response personnel.  Plant management makes information available to the local community regarding the hazards and risks in operating the facilities and 
the prevention techniques in place.  This includes insuring that all regulatory reporting requirements are met. 
Plant management is fully informed as to the materials which are stored or used on-site and aware of the possible risk associated with their handling, storage, use, disposal or accidental release.  Material Safety Data Sheets (MSDS) for all materials utilized at the plant are maintained on-site and reviewed bi-annually.  The plant maintains up-to-date procedures to insure the proper control of hazardous materials. Procedures and systems are devised which include provisions for the periodic testing, review, and update of the emergency response programs.  
Employees are trained and periodically retrained in the methods of detection of hazardous material releases, the potential physical and health risks associated with the materials, and methods for protecting themselves, co-workers, and the public.  The plant investigates, corrects, and reports in writing all incidents involv 
ing hazardous materials having caused, or having the potential for causing, injury or loss. 
Strict adherence to this policy is essential in reducing the risk of accidental releases of hazardous materials and in decreasing the likelihood of adverse impacts to Cargill's employees, the local communities and the environment. 
1.2 Risk Management System 
Cargill Corn Milling Division's Blair plant has developed a management system to oversee the implementation of the Risk Management Program in accordance with the requirements of 40 CFR Part 68, Subpart G.  The management system (shown in Figure 1-1) identifies job functions by responsibility level. 
Figure 1-1   Management Organization for Risk Management Plan 
                 Facility Team Leader 
                Operations Team Leader 
Safety Coordinator     Department Team Leaders    Environmental Coordinator 
                   Shift Leader 
Responsibilities of Facility Team Leader: 
- Oversight of facility operations 
- Review and approve facility safety policies/pr 
- Facility spokesperson 
Responsibilities of Operations/Department Leaders: 
- Implementation of Process Safety Management Program 
- Completion of incident investigations 
- Follow-up to audit findings 
- Oversee and document maintenance 
- Management of change and pre-startup safety reviews 
- Department specific employee/contractor safety training 
- Compliance with facility safety policies/programs 
- Development of operating procedures 
Responsibilities of Safety Coordinator 
- Develop/review facility safety policies/programs 
- Develop facility PSM policies/procedures  
- Oversee contractor safety program 
- Track new regulations 
- Oversee compliance audits 
- Oversee facility safety training programs 
Responsibilities of Shift Leader: 
- Incident Commander for emergency response 
- Management of various response teams (First Responders, 
 HAZMAT, Confined Space Rescue) 
- Development of facility Emergency Response Plan  
- Planning and execution of emergency drills 
ties of Environmental Coordinator 
- Oversee implementation of RMP 
- Track new regulations  
- Oversee compliance audits 
- Oversee facility environmental training programs 
The Cargill Foods Corn Milling Division plant in Blair produces high fructose corn syrup, ethanol, corn oil, and other products, such as gluten feed and meal, from the corn milling process.  The raw materials and process chemicals utilized by the plant are delivered via truck and rail from external sources.  Access to the site by vendors, employees and visitors is controlled by fencing and security check points.  Sulfur dioxide is the only chemical utilized in the corn milling process at the Blair facility that is regulated under 40 CFR Part 68.  The process department utilizes SO2 that is subject to the above regulation which addresses the potential off-site hazards of an accidental release of sulfur dioxide (SO2). 
The EPA Risk Management Regulation iden 
tifies three levels of requirements for industrial processes.  Program 1 can be applied to any process which has not had a "significant" release of a regulated substance over the five year period prior to the June 1999 compliance date and for which the worst-case release does not affect "public receptors" (e.g., residences, parks and recreation areas, commercial/industrial facility, hospitals).  Program 2 applies to any process that is ineligible for Program 1 and is not subject to Program 3.  Program 3 applies to all processes, such as those present at the Cargill Corn Milling Division facility, that are subject to the Occupational Safety and Health Administration (OSHA) Process Safety Management Standard (PSM). The Cargill Accident Prevention Program elements are adopted directly from the compliance program for the PSM standard, consistent with the Level 3 RMP Program requirements for this Cargill facility under 40 CFR Part 68.  Program 3 related information for the Process departmen 
t is included in the Data Elements section of the Risk Management Plan. 
2.1 Process Department 
The corn milling process at the Cargill Blair facility is designed to extract useable starch and sugars from corn kernels in order to produce various end-products. The first step in the corn milling process involves steeping the corn kernels in water tanks, into which liquid SO2 is injected. The SO2 and water form a dilute solution of sulfurous acid that helps to soften the kernel, breakdown proteins and remove soluble constituents. The steeped corn then travels through degerminating mills and separation processes designed to remove the germ and separate out the starch.  This starch slurry is utilized in the production of high fructose corn syrup, dextrose and ethanol.   
The Process department is responsible for the storage and transfer of sulfur dioxide (SO2) that is utilized in the corn milling process. The SO2 is stored in an exterior storage tank as a pure liquefied gas at ambient temp 
eratures. The maximum amount stored at any time is 304,000 lbs.  The storage tank is filled approximately every 10 days via 90-ton railcar.  Access to the loading area is limited by chain link fence and secured by locks.  Only authorized personnel are allowed to perform tasks within this area. 
For the purposes of developing and maintaining adequate Risk Management Plans, the EPA has defined in its governing rules and guidance a series of modeling methods and assumptions which are to be used as administrative guides for planning purposes.  In order to standardize and simplify the many factors that can potentially occur in an accidental release situation, some of these assumptions may not take into account the available preventive measures or mitigation methods that could diminish or even eliminate the implied risks that are suggested by "worst-case" analyses. For that reason, both the results for the standardized "worst-cases" defined by the EPA methods and a s 
et of alternative cases which are believed by Cargill to more realistically represent situations that may possibly, but rarely, occur within the lifetime of the facility are also presented. The sections of the Risk Management Plan which discuss both worst-case, and alternative cases, are meant to provide the data necessary to develop and evaluate possible improvements in the overall safety programs of the Cargill RMP program.  
3.1 Worst-Case Release for Toxic Substances 
The worst-case release scenario, as defined by 40 CFR Part 68, is a sudden release of the maximum amount of a stored regulated substance from a single vessel, regardless of whether several vessels are interconnected.  For toxic gases such as SO2, stored at ambient temperatures it is assumed that the release occurs over a 10-minute period.  The regulated substance with the most extensive zone of influence, defined as the distance to specified "toxic endpoints", is considered the worst-case release for each facility.  O 
nly passive mitigation (e.g., dikes, enclosures) and administrative controls may be accounted for in the evaluation. 
EPA has established "toxic endpoints" for various chemicals based on the American Industrial Hygiene Association (ACGIH) Emergency Response Planning Guideline, Level 2 (ERPG-2), which protects individuals from health-threatening or escape-impairing injury.  The ERPG-2 is defined as: 
"the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to 1 hr without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action." 
Given that the worst-case is a 10-minute release duration with a 10-minute averaging time, the actual hazard zone is typically overestimated by the ERPG-2. Within such a time period there are a number of emergency measures that can reduce or eliminate exposures to levels this high for an interval much shorter 
than an hour. 
The EPA's RMP Off-site Consequence Analysis Guidance (1999 Revised OCAG) lists a number of refined dispersion models that are available for off-site hazard assessment applications for risk management programs.  Sulfur dioxide has a molecular weight that is substantially greater than the ambient air.  Therefore, concentrated plumes of this substance resulting from accidental releases often display heavy-gas behavior.  In such cases, near-field dispersion is dominated by gravitational slumping of the plume and entrainment of air at the plume-air interface.  The Dense Gas DISpersion (DEGADIS) Model (Version 2.1) was developed by the U.S. Coast Guard and the Gas Research Institute to model dense gas releases and its use has been approved by the U.S. EPA.  The model is used to predict the dispersion of dense gases from ground level releases over flat, level terrain.  For these reasons, DEGADIS was used to model the worst-case release scenario. 
The 1999 Revised OCAG provide 
s a basic approach to estimating endpoint distances based on an ambient air temperature of 77oF.  However, the RMP rule requires that if dispersion techniques other than the OCAG are applied, the maximum daily temperature over the last three years be used.  A review of National Climatic Data Center (NCDC) climatological data for the National Weather Service reporting station at Omaha, NE, indicated a recorded high temperature over the last three years of 98oF. 
Under Section 68.22 (e), the RMP rule identifies "surface roughness" as a parameter to be specified in the hazard assessment. The surface roughness affects the amount of dispersion that occurs within a released plume and influences the distance to "toxic endpoint." The surface roughness used in determining the distance to toxic endpoint should be characteristic of the transport path of the plume from the release point to the endpoint distance.  'Urban' surface roughness indicates areas where there are many obstacles, such as ind 
ustrial buildings or trees.  'Rural' indicates that there are no buildings in the immediate vicinity of a facility and that the terrain is generally flat and unobstructed.  
In the immediate vicinity of the Cargill Corn Milling facility, the aerodynamic surface roughness is clearly 'urban' in nature, whereas at greater distances, the surface roughness is 'rural'.  In order to report the most conservative 'distance to toxic endpoint' estimates in the Risk Management Plan, Cargill has elected to model the release assuming a "rural" surface roughness.  A rural surface roughness value of 10 cm, which is consistent with the land use surrounding the facility, was utilized in the DEGADIS model. 
In accordance with 40 CFR Part 68, the worst-case modeling is conducted assuming a very stable atmosphere with limited dispersion (F stability and 1.5 m/sec wind speed).  Analysis of three years of meteorological data from the National Weather Service at Omaha, NE indicates that these dispersion condi 
tions occur approximately 5% of the time (or about 1.2 hours per day, on average). The wind rose  (Figure 3-1), based on the three-year period 1989-1991, indicates that the most predominant directions of transport are to the north and northwest.  
The toxic endpoint for SO2 is 0.0078 mg/L.  Since the resulting planning zone predicted for the "worst-case" SO2 toxic release potentially affects public receptors, regulated processes at the Cargill Corn Milling Division facility are subject to Program 3 requirements.  
3.1.1 Worst-Case Release: Sulfur Dioxide 
The 40 CFR, Part 68 prescribed worst-case scenario for the Blair facility consists of a 10-minute gaseous ground-level release of 304,000 lbs of stored SO2, dispersed under atmospheric conditions of F stability and 1.5 m/sec wind speed.  The modeling results indicated that the worst-case SO2 release would result in a distance to toxic endpoint of 13 miles. The worst-case impact zone encompasses a resident population of approximately 3 
0,000, based on the 1990 Federal Census, and estimated by applying EPA's Landview III program.  Public receptors were identified using 1:24,000 scale U.S.G.S maps, supplemented with comprehensive maps of the local Blair area (Rand McNally, 1990, and DeLorme Street Atlas USA, Version 5).   The potential worst-case hazard zone includes schools, hospitals, public recreation areas, and industrial/commercial areas. Cargill has established separate written emergency response plans to coordinate with local industrial facilities in the unlikely event of a chemical release.  Several environmental receptors (defined as National or State parks, forests, officially designated wildlife sanctuaries, preserves, refuges, and federal wilderness areas) are also located within the worst-case impact zone. The closest environmental receptor is the California Bend State Wildlife Refuge.  
Cargill notes that it is impossible to release 304,000 lbs of SO2 in 10 minutes because the amount of heat energy requir 
ed to so rapidly vaporize the liquid SO2 would not be available.  Even if the storage tank were to breach, SO2 would spill to the ground in a boiling liquid pool.  If a hole were to form in the vapor space of the storage tank, the flashing vapor in the tank would cause the tank to auto-refrigerate, thereby gradually reducing the release rate with time.  However, Cargill evaluated this 10 minute release to comply with the noted regulation. 
3.2 Alternative Releases of Toxic Substances 
Alternative releases are intended to represent release scenarios that have a greater likelihood of occurrence than a worst-case release.  Alternative releases do not necessarily represent the types of releases that the PSM hazards analysis and/or accident history indicate would be most frequent, but rather a release that is somewhat more likely than the worst-case release and that generally still has the potential to affect off-site receptors. In accordance with the EPA's OCAG, a single alternative releas 
e scenario is reported for each regulated substance.  
Cargill performed a thorough review of the SO2 storage and unload systems in the Process department utilizing engineering plans, operational experience, and maintenance records, in order to determine alternative release scenarios that could potentially result in off-site impacts. Each scenario was evaluated and the scenarios most likely to occur and to result in off-site impacts were selected for modeling. In order to determine the most conservative off-site consequence estimates, Cargill has chosen to include in the Risk Management Plan the alternative release scenario that resulted in the greatest "toxic endpoint" distance for SO2. 
In accordance with the RMP rule, alternative releases are modeled under typical (rather than worst-case) dispersion conditions.  The EPA OCAG default dispersion conditions are neutral atmosphere, with dispersion neither enhanced nor limited (D stability and 3 m/sec wind speed). A review of climatologi 
cal data for Omaha, NE, confirmed that conditions of D-stability and windspeeds of 3 m/sec and greater are typical of the area and therefore are suitable for the evaluation of alternative releases. Unlike the worst-case release (for which an instantaneous spill or 10-minute ground-level gas release is assumed), alternative scenarios can account for the actual release configuration, and account for both active and passive mitigation. 
Alternative dispersion modeling was conducted using EPA's RMP Off-site Consequence Analysis Guidance (1999 Revised OCAG).  As with the worst-case scenarios, only the modeling results based on 'rural' surface conditions are included in the Risk Management Plan, in order to report the most conservative 'distance to toxic endpoint' estimates.  However, it should be noted that, under actual conditions, plume dispersion would be enhanced by the 'urban' type surfaces near the facility, and result in shorter distances to "toxic endpoint". This is especially true  
for alternative releases, where distances to "toxic endpoints" are typically less than the "worst-case".  For comparison purposes, both the 'urban' and 'rural' modeling results for the alternative release scenario have been included in the Risk Management Plan Executive Summary. 
3.2.1 Sulfur Dioxide 
The alternative SO2 release scenario that would result in the greatest off-site impact involves a break in the SO2 unloading assembly at the delivery railcar.  A break in the unload assembly might occur if, for example, the railcar was bumped/pushed while unloading SO2.  For this scenario, the assumptions have been made that the SO2 railcar track has not been locked out and the railcar wheels have not been chocked in accordance with standard unload procedures.  Also, it is assumed that the railcar is pushed far enough to take up all the slack in the flexible hose portion of the apparatus; and that all automatic interlocks on the system fail to engage.   
A break in the unloading assembly  
of this type would result in a hole in the unloading assembly of approximately 1.0 inch in diameter.  The pressurized release of SO2 through hole of this size would result in two-phase flow (vapor and liquid) as the pressurized SO2 flashed to the vapor state.  The modeling showed that SO2 would be released at a rate of 1600 lbs/min.  It is conservatively assumed that the sulfur dioxide would then be dispersed as a heavy gas and the excess flow valve in the railcar would not engage.  Cargill has estimated that it would take an operator approximately 30 minutes to respond and shutdown the flow of SO2, resulting in a total release of 48,000 lbs.  This alternative SO2 release scenario is expected to be more representative of the maximum anticipated release at the facility than the "worst-case".   
The 1999 Revised OCAG indicates that under 'rural' conditions, the distance to "toxic endpoint" would be 1.9 miles.  Under 'urban' conditions, the distance would be approximately 0.6 miles.  The  
hazard impact zone encompasses an estimated residential population of approximately 2000 persons, based on the 1990 Federal Census, and estimated in conjunction with EPA's Landview III database program. Public receptors in the alternative impact zone include schools, public recreation areas, and industrial/commercial areas.  No environmental receptors would be affected. 
Some processes subject to the Risk Management Regulation are also subject to Occupational Safety and Health Administration (OSHA) Process Safety Management Standard (PSM).  PSM governs the same processes and regulated substances at the site that are subject to 40 CFR Part 68.  Cargill has a PSM program at the Blair plant that includes the following elements: 
- Employee Training and Participation  
- Process Safety Information  
- Process Hazards Analysis  
- Operating Procedures  
- Training 
- Contractors 
- Pre-Startup Safety Review 
- Mechanical Integrity 
- Hot Work Permit 
- Ma 
nagement of Change  
- Incident Investigation 
- Emergency Planning and Response 
- Compliance Audits 
- Trade Secrets 
In conjunction with the current RMP and PSM programs in place at the Blair plant, there is a standard management practice that requires internal reporting of unusual events, including those in which any abnormal emission of regulated chemicals is observed or suspected.  The incident information is reviewed and a determination is made as to whether a reportable quantity on any chemical listed as requiring reports to regulatory authorities is involved.  If so, the appropriate authorities are notified. 
During the past 5 years (June 1994 to June 1999), there has been no accident involving any RMP regulated substance that qualifies for reporting under 40 CFR Part 68.  This means that no accident has resulted in reportable on-site injury, off-site injury, emergency response, or damage to property or the environment. 
Cargill's Blair plant has established an Emergency Action Plan that is designed to address foreseeable emergency situations at the facility and provide appropriate hazard and emergency preparedness information to employees, contractors, emergency response personnel, and the community.  Emergency situations can include fire, explosion, chemical release or spill, bomb threat, weather emergencies and other natural emergencies.  Due to the ongoing risks that are presented by weather emergencies like tornadoes, the plant has in place an emergency plan to protect both the plant operational integrity and the safety of its workers and neighbors from weather emergencies.  In regards to chemical releases, Cargill has developed a command structure and specific procedures that must be adhered to in the unlikely event of a chemical emergency.  These procedures define the criteria for identifying, classifying, and notifying the appropriate emergency response staff of potential emergenc 
y events. If a chemical release is detected on-site, the emergency response team is notified and the most appropriate mode of response is determined by the Incident Commander, with support from available emergency response (HAZ-MAT) teams and technical advisory staff.  Each Department in the facility must also follow a specific Spill Prevention Countermeasure and Control Plan in the event of a chemical release.  
Plant operations at the Blair facility can present various types of potential hazards and Cargill recognizes the need to have a well trained and prepared work force to safely and effectively deal with any emergency situation.  The Cargill Blair facility provides training of responsible staff and the exercise of important communication links with the community, in order to maintain an appropriate state of readiness for emergency situations.  Cargill Blair plant staff attend quarterly meetings with local industry and emergency response planning officials and have participated in 
emergency response training exercises.  Cargill staff have a "First Response" capability and are able to administer basic first aid and CPR.  Cargill and local emergency response planning officials also rely on the Memorial Community Hospital to offer paramedical assistance and transportation to the hospital. 
Cargill's Blair plant, under the recent RMP program, as well as its existing PSM and earlier SARA Title III Community Right-to-Know Act compliance programs has organized its management system to effectively address hazards and potential risks.  Both the advanced planning aspects of process design, operating procedures, and emergency preparedness, and the operational elements of system maintenance, safe operating practices and ongoing personnel training are necessary to support a continual improvement in facility safety.  These programs are documented so that information about the safe handling of chemicals present at the facility is ava 
ilable to all employees, and can be interpreted by emergency response team staff and the Incident Commander. This is especially important when questions arise from public safety officials regarding potential risks to the community.  All of these features of the RMP and the integrated risk management program at the Blair plant lead to operations that are safe today, but will be even safer tomorrow. 
Cargill Blair's safety program incorporates continuous improvement through use of on-going evaluations of in-plant safety and program effectiveness.  
Risk Management Plan Executive Summary    June, 1999
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