Albemarle Corporation South Plant - Executive Summary |
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About our Facility: The South Plant Facility is located in rural Columbia County, about six miles south of Magnolia, Arkansas. Land use in the immediate vicinity of the site is primarily agricultural, with silviculture predominating. The plant is located astride a low hill or ridge east of Horsehead Creek. The location of the plant is due to the presence of natural brine deposits located about 1.5 miles beneath the plant. These brines are withdrawn through a system of wells and processed to produce bromine and hydrogen sulfide, and then replaced into the same geologic formation by a second system of wells. The South Plant produces bromine, sulfur, fire retardants, pesticides and pesticide intermediates, clear completion fluids and other speciality chemicals. About our accidental release prevention and emergency response policies: The South Plant Facility has very active accidental release prevention and emergency response programs. It is the policy of the S outh Plant Facility to reduce the risk of chemical release to the extent feasible. The main vehicle for chemical risk reduction is the Process Safety Management (PSM) program. When the OSHA PSM standard was promulgated, existing programs were subsumed into the PSM program following the OSHA standard. The Policy of the South Plant is to first prevent the occurrence of emergency situations, but if prevention measures are unsuccessful, to respond to those situations in a professional and appropriate manner. The site has an integrated Emergency Plan which follows EPA's "One Plan" concept. South Plant personnel respond to emergencies on site with a trained fire brigade, HazMat responders, and a corps of trained EMTs. The emergency plan provides for coordination with local care givers, first responders, law enforcement, and the county emergency response infrastructure through the county-wide emergency plan. Briefly, if a chemical incident appears to have the potential for off site impact, the local County Emergency Coordinator would assume situational control, while South Plant personnel work to mitigate the problem. If a situation has impact beyond the borders of Columbia County, the county-wide emergency plan provides for coordination with adjoining counties and parishes. All of our south Arkansas facilities use the same basic accidental release prevention and emergency response programs. Using the same plan makes training easier and coordination with local off site responders better. Details of the emergency plans (such as maps; locations of response equipment) are different due to the physical differences in the facilities. Regulated substances handled at the South Plant: The South Plant is known to handle as many as fifteen listed chemicals in up to 21 processes. Information on the handling and storage was gathered. Eleven regulated chemicals in eight processes were found to be subject to the RMP rule. The accidental release prevent ion and emergency response programs are exactly the same for covered and non-covered processes; covered and non-covered chemicals are both subject to both programs. The Risk Management Program has been incorporated into the PSM program to provide continuity. A description of our risk management program is found below. Our accidental release prevention program: We have included chemical specific steps for release prevention under each alternate-case scenario below. The South Plant Facility is subject to the OSHA PSM standard. We have internal procedures which drive compliance with both the OSHA PSM standard and the new EPA RMP standard. We have compiled detailed information on all process (both covered and non-covered) which includes hazard information on each substance, technical process information, and process equipment information. This information is used in the Process Hazard Analysis (PHA). PHA's have been conducted on all processes, and are repeated according to a regular schedule (maximum of 5 years) or when certain events trigger performance of the PHA. The PHA identifies any and all possible mishaps, the likelihood and consequences of mishaps, and predicts how safety and mitigation systems will perform in the event of a mishap. For each PHA, a team is formed which possesses the requisite expertise in engineering, process operations, hazard analysis, industrial hygiene, safety systems, and emergency response. Several standard methods may be used to analyze the available information, and more than one method may be applied to a process hazard analysis. The PHA documentation is retained for the life of the process. This information is used to eliminate hazards when possible, and mitigate those hazards when elimination is not possible or impractical. Standard Operating Procedures (SOPs) exist when each process is first started up, and undergo continual review and improvement. Some of the items included in SOP's are proc edures for start-ups, shut-downs, routine or hazardous procedures, operation of safety and environmental control systems, and mitigation of process hazards. SOPs are updated to reflect current operating conditions. Each SOP is reviewed no less often than annually. Training is the key aspect of accident prevention. Each employee in an operating process receives job specific and general training on safety and health hazards, emergency operations, and safe work practices. This training is administered according to the needs of the employee and the specific requirements of the program. Preventative Maintenance (PM) is an integral part of our accidental release prevention program. Our PM program addresses equipment and controls whose failure could lead to injury, significant release, or property loss. The program includes regular inspections and tests of process equipment consistent with manufacturer's recommendations, good engineering practices, and field experience. Doc umentation of the results of tests and maintenance is maintained. When a new or modified system is started up for the first time, the likelihood of unexpected consequences is increased. For this reason, pre-start-up reviews are conducted with the aim of insuring that; design specifications are adequate and have been met; adequate safety, operating, maintenance, and emergency procedures are in place; and that employee training is adequate and has been completed. Many historical accidents may be traced to a seemingly minor or inconsequential process change. We manage process changes through a system that insures the impact of a change is assessed and appropriately addressed before the change is implemented. Part of this program (Management of Change) is communication of the change and anticipated effects to all affected employees, and training provided as necessary. To assure compliance with this program, regular audits are conducted. We make every effort to min imize risk through training, preparation, and planning. Yet an incident may occur. When an incident occurs, an investigation is performed to determine the root causes for the incident and to recommend corrective action to prevent a reoccurrence. These investigations are performed on minor (even trivial) incidents. Lessons learned on trivial (no impact) and "near miss" incidents often can often be used to teach us how to avoid more serious consequences. Documentation of the investigation is maintained. The best source of information about process hazards is employees who work in an existing process. Line employees are an integral part of our process of chemical hazard analysis. Employee access to the results of PHAs and other aspects of the risk management program is insured and encouraged. We use a permit system to insure that all aspects of a job (non-routine) must be considered before performing that job. Each process issues Safe Work Permits for non routine jobs do ne in that area each day. Permits generally expire at the end of a shift and are critical to communicating jobs in progress within a process area. A Safe Work Permit may require the permittee to initiate and complete a Hot Work Permit before performing certain tasks. Sometimes, tasks involving welding, cutting, braising, or other flame or spark producing activities, must be performed in areas where flammable chemicals are present. Hot work permits insure fire prevention and protection requirements have been implemented prior to beginning the work. Another essential part of the risk management program is the use of "lock out/ tag out" procedures. When a safe work permit is issued, the permit requires the permittee to assure that all sources of potential energy have been deactivated. For instance, the permittee may perform the following procedures before working on a pump: Check the Safe Work Permit to make assure operations has purged and drained the pump; check the red tags in p lace to make sure the pump is isolated from the process; and place a personal locking device on the electrical switchgear energizing the pump. No employee can remove a red tag, actuate a tagged component, or remove a personal locking device placed by another employee. We depend on contractors and contract employees for many essential services. Under our PSM program, we insure that contractor preformed maintenance, repair, and general operations are preformed safely. Contractors are fully informed of the potential hazards of the relevant processes and applicable portions of the facility emergency response plan. The contractor, in turn, must control the entry, presence, and exit from process areas. The contractor, as a condition of employment, must adhere to all facility safe work standards and practices. You will find specific prevention program information in section 7 of this plan. Section 8 does not apply to this facility. Facility five year accident history: The South Plant has been relatively free of offsite consequences. The EPA RMP program requires reporting on "regulated" chemicals in "covered" processes in the five years proceeding the date of RMP submission. Although the South Plant does not have any incidents which meet the EPA criteria, we have had releases of chemicals which had offsite consequences. Periodically, neighbors call and report odors. These reports are investigated and a serious attempt is made to determine the origin of the odor. If the odor is found to be originating at the South Plant, all efforts are made to mitigate the odor at the source. There have been releases in the past with potential offsite consequences. For instance, in 1987 an expansion joint below a vessel filled with bromine chloride failed, allowing the entire contents to flow into a diked area. (This chemical is no longer produced at the South Plant.) Stable wind conditions carried the vapor cloud due west into a forested portion of the facility. Vegetation in this forested area was affected, and the release could have necessitated an offsite response if the wind direction had been different. Facility emergency response program: Our emergency response plan is in the format developed by EPA. This format is commonly known as the "One Plan." This particular format was developed to address the off site responder need for simplicity while complying with all regulatory requirements. The emergency response program is based on the principle that the facility should respond to incidents within the scope of the facility's expertise, while the local authorities respond within the scope of the Columbia County Emergency Response Plan. This means that the facility is responsible for preventing incidents before they happen. But if a incident does occur, the facility is responsible for mitigating the offsite consequences of the incident by source control. The Columbia County Department of Emergency Management is charged with implementing the Columbia County Emergency Plan and coordinating the response. The Columbia County Emergency Plan was developed by the Columbia County Local Emergency Preparedness Committee (CCLEPC) under the direction of the Columbia County Department of Emergency Management Coordinator with the aid of the Columbia County Judge. The South Plant Emergency Plan contains procedures for response to chemical releases, fires, and natural disasters. Provision is made for informing the public through responsible officials according to the provisions of the County Emergency Plan. The emergency plan describes the location and mode of use of specialized emergency response equipment. The plan also describes the delivery of medical treatment for injuries. Public awareness is an important component of an emergency response program. The South Plant facility seeks to maintain continual contact with the public through regular meetings of the Community Advisory Panel ( CAP). The CAP advises the facility on the need, frequency, and effectiveness of public communications. Planned changes to improve safety: The best way to protect the public is by preventing accidents. We use the Process Safety Management process to identify and prevent chemical releases. The PSM process drives continual improvement in process safety. Offsite, the facility has been active in supporting (through donations, participation and membership) the CCLEPC since its formation in 1987. EPA's implementation of the Clean Air Act Amendments of 1990 caused us to examine, and plan for, incidents which are extremely unlikely. As a result of this examination, the entire emergency response process has benefitted. Two CCLEPC initiatives are worthy of mention. The first is the filming of a public service video, which instructs the public how to "shelter in place." The second is the purchase and installation of an automated telephone system capable of calling citizens likely to be affected by a chemical emergency or natural disaster and delivering specific instructions. General comments about chemical release scenarios: All release modeling included in this plan comes from EPA's "Off Site Consequence Analysis Guidance," May 24, 1996, extensively revised April 15, 1999. Endpoint distances were calculated using the EPA provided tool "RMP Comp, Ver. 1.06." Other versions of "RMP Comp" may not provide the same results as Ver. 1.06, the latest version available in May, 1999. The output text file from "RMP Comp" is quoted in each scenario. The Worst Case Scenario (WCS) is rigidly defined by the RMP rule. For simplicity's sake, we have used the recommendation of EPA guidance for atmospheric conditions. For the WCS, this is a temperature of 77 deg. F., wind speed 1.5 meters per second, atmospheric stability class F. For the Alternate Case Scenarios these conditions are 77 deg. F., wind speed 3.0 meters per second, and atmospheric class D . In both WCS and ACS, the forested, rolling terrain around the South Plant is characterized by a surface roughness factor "urban." When interpreting impact, it should be remembered that an actual release travels in the direction of the prevailing wind, and does not disperse much toward the sides of the centerline of the direction of travel. Information on the Toxics WCS is found in section 2 of this plan; section 3 contains Toxics ACSs. The flammables WCS is found in section 4 and the ACS in section 5 of this plan. The Alternate Case Release Scenarios (ACS) were developed by a knowledgeable panel of safety, industrial, and environmental professionals. This panel reviewed several sources in developing the scenarios: Actual reported incidents; Process Hazard Analyses (PHAs); Data from the EPA ARIP database (nationwide); and collective process hazard knowledge. Although some of the ACS may have roots in actual recorded incidents, the scenario may have been intentially manipula ted so as to have off site consequences which were absent in the real incident. For instance, two real incidents may have been combined to have more serious consequences (for modeling purposes) than did the actual incident. The most weight was given to the concerns of the process unit leadership. For public receptor identification, we used reports generated for use in the RMP program by Environmental Data Resources of Southport, Connecticut. Public receptors were estimated from these reports, and the "Landview III Environmental Mapping Software" developed by the EPA and the Department of Commerce. Toxic chemical worst-case release scenario: At the South Plant, the Worst Case Scenario (WCS) is a sudden release of all the chlorine in four chlorine rail cars (720,000 pounds) in 10 minutes. The conditions are for a wind speed of 1.5 m/sec, atmospheric stability class F, air temperature 77 deg. F. The forested, rolling terrain around the South Plant is characterized by a sur face roughness "urban." "RMP Comp" estimates the distance to the toxic endpoint as greater than 25 miles. Results of the WCS may be found in section 2. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Chlorine CAS #: 7782-50-5 Category: Toxic Gas; Scenario: Worst-case; Liquefied under pressure; Quantity Released: 780,000 pounds; Release Duration: 10 min.; Release Rate: 78,000 pounds per min.; Mitigation Measures: NONE; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.0087 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: >25 miles (>40 kilometers); report as 25 miles Assumptions About This Scenario: Wind Speed: 1.5 meters/second (3.4 miles/hour); Stability Class: F; Air Temperature: 77 degrees F (25 degrees C)." Chlorine rail cars are ruggedly constructed and there is negligible likelihood of the simultaneous breach and emptying of four parked rail cars on a siding (in the absence of military action). T oxic chemical alternate-case scenario #1: The first South Plant Alternate Case Scenario (ACS) is for a release of anhydrous ammonia. Ammonia is gas under standard conditions, and is stored liquefied under pressure. The scenario selected for ammonia is for a 1" nipple connecting a gage to a storage tank to catastrophically fail, with subsequent spill of 40,000 pounds of anhydrous ammonia in 21 minutes. Subsequent investigation reveals the gage fitting was brass instead of carbon steel. "RMP Comp" reports a distance to endpoint for this scenario of 0.3 miles. All ACS results can be found in section 3. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Ammonia (anhydrous) CAS #: 7664-41-7 Category: Toxic Gas; Scenario: Alternative; Liquefied under pressure; Release Duration: 21 minutes; Storage Parameters: Hole in liquid space of tank; Hole or puncture area: 0.79 square inches; Height of Liquid Column Above Hole: 48 inches; Release Rate: 1,900 pounds per min.; Mitigation Measures: NONE; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.14 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 0.3 miles (0.5 kilometers) Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." This scenario is based on an actual incident (vapor fitting rather than liquid service). Preventative measures include facility personnel attended unloading; checking all valves and fittings for proper materials of construction; and posting signs in the area listing proper materials of construction. Toxic chemical alternate-case scenario #2: The second South Plant ACS is for a release of bromine. Bromine is a liquid at standard conditions. This scenario is based on an actual incident which occurred in 1990. This scenario postulates the failure of an expansion joint (due to over pressuring of the tank) joining a bromine c ontaining vessel at 50 psi pressure with a sight glass. This rupture could result in the release of 90,900 pounds of bromine into a 667 square foot containment structure in 9.98 minutes. "RMP Comp" reports a distance to toxic endpoint of 1.2 miles for this scenario. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Bromine CAS #: 7726-95-6 Category: Toxic Liquid; Scenario: Alternative; Quantity Released: 90,900 pounds; Release Duration: 9.98 minutes; Storage Parameters: Pressurized Tank; Hole or puncture area: 3.14 square inches; Height of Liquid Column Above Hole: 6 feet; Storage Pressure: 50 psi.; Release Rate: 9,110 pounds per min.; Liquid Temperature: 77 F.; Mitigation Measures: Diked area: 667 square feet; Dike height: 3.17 feet; Release Rate to Outside Air: 117 pounds per minute; Evaporation Time: 778 min; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.0065 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 1.2 miles (1.9 kilometers) Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." Expansion joints are no longer used in this service. Auxiliary pressure relief devices have been installed to provide automatic depressuring of the vessel before over pressure occurs. In the actual incident, there were no off site consequences. In actual practice, a contained liquid bromine pool would be covered with a layer of water, which reduces bromine vapor evolution by orders of magnitude. The bromine, thus contained, could then be either returned to process or neutralized in place according to the provisions of the emergency plan. Toxic chemical alternate-case scenario #3: The next South Plant ACS is for a release of chlorine. Chlorine is received in rail cars and is connected to rigid piping by a special flexible hose. A scenario which postulates a punctured rail car is not reasonable (lack of history nationwide). The ACS scenario selected for chlorine is based on an actual incident which occurred in 1993. In this scenario, liquid chlorine is routed to the atmosphere via a partially open atmospheric vent valve (0.79 square inches) that should have been closed before unloading began. Also, the scrubber is not operational during this scenario, and it takes 30 minutes to find the problem. Chlorine leaks at a rate of 34.2 pounds per minute until the partially opened valve is found, or the scrubber returned to service. "RMP Comp" returns a distance to toxic endpoint of 0.8 miles for this scenario. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Chlorine CAS #: 7782-50-5 Category: Toxic Gas; Scenario: Alternative; Liquefied under pressure; Release Duration: 30 minutes; Storage Parameters: Release from Pipe; Initial Operational Flow Rate: 34.2 pounds per min; Cross-sectional area of pipe: 0.79 square inches; Operational pipe pressure: 100 psi.; Chan ge in pipe elevation: 0 feet; Release Rate: 2,900 pounds per min.; Mitigation Measures: NONE; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.0087 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 0.8 miles (1.3 kilometers). Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." In the actual incident, the leak was found in about 5 minutes and the scrubber was operational. To prevent this from happening again, we installed a pressure indicator on the vent header to indicate a liquid leak; installed a remotely operated block valve on the vent header and installed a pressure control valve on the vent header to prevent potential over pressure of the scrubber. Toxic chemical alternate-case scenario #4: The next South Plant ACS is for a release of hydrogen sulfide. This scenario is based on an actual incident which occurred in 1991. I n this scenario, a 3 inch diameter carbon steel ell in pressurized (110 psi) service fails, causing a release to the atmosphere. The 30,900 gallon tank vents down completely in 51 minutes at a rate of 47.4 pounds per minute. "RMP Comp" estimates a distance to the Toxic Endpoint of 0.3 miles for this scenario. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Hydrogen sulfide CAS #: 7783-06-4 Category: Toxic Gas; Scenario: Alternative; Release Duration: 51 minutes; Storage Parameters: Hole or puncture area: 0.375 square inches; Tank Pressure: 110 psi; Tank Temp: 85 F.; Release Rate: 47.4 pounds per min.; Mitigation Measures: NONE; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.042 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 0.3 miles (0.5 kilometers) Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." When this incident occurred, the vessel was vented to an emergency flare, considerably reducing the total emission. To keep this incident from happening again, we installed a block valve directly against the vessel to isolate downstream piping when necessary. We installed panel heater coils on the vessel to reduce the possibility of internal corrosion, and upgraded the standard materials of construction in this service. Toxic chemical alternate-case scenario #5: The next South Plant ACS is for a release of methyl mercaptan. Methyl mercaptan is a toxic gas is which has a very bad odor even in very low concentrations. The unit leader of the DMTDA process believes the scenario most likely to have serious (other than odor) offsite consequences is a failure of the gasket on the bottom nozzle of the methyl mercaptan storage tank. A failure of this gasket would result in the release of 191,000 pounds of methyl mercaptan at a rate of 821 pounds per minute in 233 minutes. "RMP Comp" est imates the distance to the toxic endpoint as 1.3 miles. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Methyl mercaptan CAS #: 74-93-1 Category: Toxic Gas; Scenario: Alternative; Liquefied under pressure; Release Duration: 233 minutes; Storage Parameters: Hole in liquid space of tank; Hole or puncture area: 0.79 square inches; Height of Liquid Column Above Hole: 144 inches; Release Rate: 821 pounds per min.; Mitigation Measures: NONE. Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.049 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 1.3 miles (2.1 kilometers) Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." Methyl mercaptan is not as "aggressive" to materials of construction as some chemicals in use at this facility. The bottom gasket on this tank is changed at the end of each campaign, when the tank is emptie d. Additionally, if the flange union is disassembled for any reason, the gasket is replaced with a new gasket. The new gasket is then pressure tested to check for leaks before it is returned to service. The relatively low release rate would allow emergency response procedures. For instance, a spray of aqueous sodium hydroxide could be used to deactivate the methyl mercaptan as it emerged from the opening. One proposed ACS considered for methyl mercaptan was based on an incident which occurred during pilot plant process development (in another state). A fairly long run of pipe was hydraulically isolated. Expansion of the methyl mercaptan in the line ruptured the line and resulted in the release of about 400 pounds of methyl mercaptan. This scenario was rejected because the process was designed with the lessons of the pilot plant experience in mind. Great care was taken in design to prevent line breaks due to hydraulic pressure. Toxic chemical alternate-case scenario #6: The next South Plant ACS is for a release of ethylene diamine (EDA). The alternate case scenario for EDA was suggested by the unit leader at the NC17 process. A similar incident once occurred in the late 1980's (bromine) at this facility. The EDA storage tank has a flange on the bottom with a block valve attached. A gasket seals the space between the two flanges (2 inches in diameter; about 0.125 inches thick). A total gasket failure could result in a release of 68,000 pounds of EDA through the 0.79 square inch opening in 136 minutes, into a 804 square foot area containment area. "RMP Comp" calculates the distance to the Toxic Endpoint as <0.1 miles. "RMP*Comp Ver. 1.06, Results of Consequence Analysis Chemical: Ethylenediamine CAS #: 107-15-3 Category: Toxic Liquid; Scenario: Alternative; Quantity Released: 67900 pounds; Release Duration: 136 minutes; Storage Parameters: Tank under Atmospheric Pressure; Hole or puncture area: 0.79 square inches; Height of Liqui d Column Above Hole: 18 feet; Release Rate: 499 pounds per min.; Liquid Temperature: 85 F; Mitigation Measures: Diked area: 804 square feet; Dike height: 2.75 feet; Release Rate to Outside Air: 5.52 pounds per minute; Evaporation Time: 12300 min.; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.49 mg/L; basis: EHS-LOC (IDLH). Estimated Distance to Toxic Endpoint: <0.1 miles (<0.16 kilometers); report as 0.1 mile Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." If this scenario were to actually occur, the emergency response plan is for a nearby fire monitor be used to "knock down" the vapor cloud. One part of the prevention program is a regular inspection of gaskets in service. Additionally, if the flange union is disassembled for any reason, the gasket is replaced with a new gasket. The new gasket is then pressure tested to check for leaks b efore it is returned to service. Toxic chemical alternate-case scenario #7: The next South Plant ACS is for a release of oleum. The unit leader at NC17 is once again most concerned with the case of a failure of a bottom gasket on one of the two oleum storage tanks. Failure of this gasket (0.125" thick, 3" diameter) could result in the release of 130,000 pounds of oleum (65% sulfur trioxide) into the 2,392 square foot containment through a 1.2 square inch opening at a rate of 1,180 pounds per minute for 110 minutes. "RMP Comp" cannot be used for any oleum concentration other than 30%. Since NC17 oleum is 65% sulfur trioxide, "RMP Comp" for 30% oleum was used to calculate the oleum release rate and duration of 1,180 pounds per minute and 110 minutes, respectively. Since neither RMP Comp nor "Offsite Consequence Analysis Guidance" provide for oleum solutions other than 30% sulfur trioxide, the oleum ACS was completed using "RMP Comp" for sulfur trioxide. The output from t hat calculation is quoted below. The distance to Toxic Endpoint was thus estimated to be 2.7 miles. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Sulfur trioxide CAS #: 7446-11-9 Category: Toxic Liquid; Scenario: Alternative; Quantity Released: 130,000 pounds; Release Duration: 110 minutes; Release Rate: 1180 pounds per min; Liquid Temperature: 85 F.; Mitigation Measures: Diked area: 2392 square feet; Dike height: 2.2 feet; Release Rate to Outside Air: 425 pounds per minute; Evaporation Time: 305 min.; Topography: Urban surroundings (many obstacles in the immediate area); Toxic Endpoint: 0.010 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 2.7 miles (4.3 kilometers) Assumptions About This Scenario; Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." In the case of an actual release such as the one described in the scenario for oleum, the containment area would be covered with a specia l vapor suppressing foam. For purposes of this plan, it was assumed that there was no response to the initial leak. Our emergency plan provides for a response with foam. Part of the prevention program is a regular inspection of gaskets in service. In addition to this regular inspection, if the flange union is disassembled for any reason, the gasket is replaced with a new gasket. The new gasket is then pressure tested to check for leaks before it is returned to service. One ACS scenario we considered for oleum was based on an actual incident in which misidentification of valve position resulted in the release of 200 pounds of oleum during a maintenance procedure. No injuries or property damage occurred. This ACS, although somewhat more likely, was rejected due to the lack of significant potential offsite impact. Toxic chemical alternate-case scenario #8: The last South Plant ACS is for a release of sulfur trioxide. The NC17 unit leader suggested that a flange ga sket failure in a 5,000 pound overhead distillate receiver drum is the scenario most likely to have off site consequences. The distillate receiver is maintained at 95 degrees F to keep the sulfur trioxide from freezing. If the bottom gasket failed catastrophically, 5,000 pounds of sulfur trioxide would spill from the 0.79 square inch opening in about 10.2 minutes at a rate of 489 pounds per minute. The approximately 7000 square foot process building would mitigate the release. "RMP Comp" estimates a distance to the Toxic Endpoint of 0.3 miles. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Sulfur trioxide CAS #: 7446-11-9 Category: Toxic Liquid; Scenario: Alternative; Quantity Released: 5,080 pounds. Release Duration: 10.2 minutes; Storage Parameters: Tank under Atmospheric Pressure; Hole or puncture area: 0.79 square inches; Height of Liquid Column Above Hole: 4 feet; Release Rate: 498 pounds per min; Liquid Temperature: 95 F. Mitigation Measures: Release in to building with floor area of 7,000 square feet. Release Rate to Outside Air: 15.4 pounds per minute. Evaporation Time: 331 min. Topography: Urban surroundings (many obstacles in the immediate area). Toxic Endpoint: 0.010 mg/L; basis: ERPG-2. Estimated Distance to Toxic Endpoint: 0.3 miles (0.5 kilometers) Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." No active mitigation is proposed in this scenario, but the pool evaporation time (several hours) would afford an opportunity to perform dilution and neutralization on the contained pool. Sulfur trioxide is stored in a tank with no bottom nozzle which negates this scenario for the larger storage tank. Gaskets in this service are regularly inspected. In addition to this regular inspection, if the flange union is disassembled for any reason, the gasket is replaced with a new gasket. The new gasket is then pressure tested to c heck for leaks before it is returned to service. An ACS considered, based on an actual incident, postulated a premature failure of a reactor rupture disk. The actual release was reported to the state, EPA, and the National Response Center, but had no offsite impact or onsite injuries or property damage. Safety relief devices are regularly inspected and rebuilt as a part of the "mechanical integrity" portion of the PSM program. Flammable chemicals worst-case release scenario: The worst-case release scenario for a release of a flammable material is for the sudden release and subsequent ignition of the contents of a storage tank containing dimethyl amine. "RMP Comp" estimates the distance to 1 psi over pressure as 0.4 miles. "RMP*Comp Ver. 1.06, Results of Consequence Analysis: Chemical: Dimethylamine [Methanamine, N-methyl-] CAS #: 124-40-3 Category: Flammable Gas; Scenario: Worst-case; Liquefied under pressure. Quantity Released: 213,115 pounds; Release Type: Vapor Cloud Explosion. Estimated Distance to 1 psi over pressure: 0.4 miles (0.7 kilometers) Assumptions About This Scenario: Wind Speed: 1.5 meters/second (3.4 miles/hour); Stability Class: F; Air Temperature: 77 degrees F (25 degrees C)." The dimethyl amine storage vessel is in a diked containment area equipped with a water flood spray system. No mitigation was considered for this WCS. Flammable chemicals alternate-case release scenario: The alternate-case release scenario for flammables is also for the release of dimethyl amine. This ACS is based on an incident which occurred in 1992, except no ignition occurred in the actual incident. In this scenario, liquid DMA back flows from the process and enters the process wastewater system, where it vaporizes. This results in a vapor cloud, which ignites. The rate assumed is 500 pounds per minute for 30 minutes. "RMP Comp" estimates a distance to 1 psi over pressure to be 0.1 miles. "RMP*Comp Ver. 1.06, Results of Con sequence Analysis: Chemical: Dimethylamine [Methanamine, N-methyl-] CAS #: 124-40-3 Category: Flammable Gas; Scenario: Alternative; Release Duration: 30 minutes Release Type: Vapor Cloud Explosion. Release Rate: 500 pounds per min; Mitigation Measures: NONE. Estimated Distance to 1 psi over pressure: 0.1 miles (0.2 kilometers) Assumptions About This Scenario: Wind Speed: 3 meters/second (6.7 miles/hour); Stability Class: D; Air Temperature: 77 degrees F (25 degrees C)." To prevent reoccurrence, we changed the relevant SOP to prevent connection of the water system to a pressurized reactor. We also installed a back flow prevention system on the dimethyl amine feed pumps, and all employees were trained in the new procedures and the process changes. |