Arch Chemicals - Mesa Facility - Executive Summary |
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ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES At the Arch Chemicals Mesa facility, we are committed to operating and maintaining all of our processes in a safe and responsible manner. A combination of accidental release prevention programs and emergency response planning programs are used to help ensure the safety of our employees and the public as well as protection of the environment. As a company, we are committed to excellence in health, safety and the environment. We recently revitalized this commitment with an ambitious new initiative - The Goal is Zero. As its name implies, this involves striving to achieve zero recordable injuries, zero environmental incidents, zero manufacturing process incidents, and zero distribution incidents. The same dedication to excellence marks our Product Stewardship initiative, under which we address health, safety and environmental performance throughout our products' life cycles. Product Stewardship and The Goal is Zero initiatives not only make good ethical and moral sense, but they respond to what our customers want and our communities expect: that we operate in a safe and environmentally sound manner. The following sections provide a brief overview of the comprehensive risk management activities designed and implemented at the Mesa facility. Also attached are the more detailed information (data elements) of our risk management program required by EPA's RMP rule. STATIONARY SOURCE AND REGULATED SUBSTANCES Arch Chemicals Mesa facility processes and supplies ultra high purity chemicals to the semiconductor and silicon wafer industries. Products include acids, etchants, solvents and custom blend formulations. In our processes, we use the following toxic chemicals that EPA has identified as having the potential to cause significant off site consequences in the event of a substantial accidental release: Anhydrous ammonia is used in manufacture of ammonium hydroxide and ammonium fluoride soluti ons. A maximum 67,200 pounds are stored on site at the facility. Ammonia solutions (>20%) are produced, packaged and stored on site prior to distribution to customers. A maximum 280,000 pounds (on a 100% basis) are handled/stored on site. Hydrofluoric acid (>=50%) is received as a raw material, distilled, diluted to <50% concentration or blended with other acids/etchants prior to packaging. A maximum 232,000 pounds (100% basis) are handled/stored on site at regulated concentrations. Hydrochloric acid (>=37%) is received as a raw material, distilled, packaged and stored on site prior to distribution to customers. Maximum 340,000 pounds (on a 100% basis) could be handled/stored on site at any one time. Our accidental release prevention programs and our contingency planning efforts help us effectively manage the hazards that are posed to our employees, the public, and the environment by our use of these chemicals. There are no RMP-regulated flammable chemicals handled or stored at/a bove threshold quantities at the Mesa facility. KEY OFFSITE CONSEQUENCE ANALYSIS SCENARIOS EPA's RMP rule requires that we provide information about the worst-case release scenario and alternative release scenario(s) for our facility. For regulated toxic chemicals, one worst case scenario having the overall greatest endpoint distance along with an alternative scenario for each toxic chemical must be reported. The following are brief summaries of these scenarios and our assessment of the potential off site consequences from accidental releases. Information about the key administrative controls and mitigation measures to limit the exposure distances are provided where pertinent. Complete details of release quantities and distances these materials could travel before dispersing enough to no longer pose a significant hazard to the public is provided in Section 3 of the RMPlan. Worst-case Release Scenario - Regulated Toxic Chemicals The selected worst case release scenario assume s failure of the storage tank containing 67,200 pounds of pure anhydrous ammonia. Company procedures limit the maximum storage volume to 86.5% of tank capacity. The default assumption is that the entire contents of the tank are released over a 10 minute period to the concrete below. Upon release, the pressurized liquid forms a pool and vaporizes to gaseous ammonia. Using the EPA OCA look up tables and EPA stipulated weather conditions (wind speed of 1.5 m/sec and F atmospheric stability class), potentially impacted public receptors include the Queen Creek schools, area residences and neighboring industries. There are no EPA listed environmental receptors within the impact distance. Although unrealistic, this scenario meets the requirements of release of the largest quantity from a vessel and has the farthest potential off site impact. Other than administrative controls to limit storage volume, no other passive mitigation measures were considered in modeling of this scenario to l imit the exposure distances. Alternative Release Scenario(s) - Regulated Toxic Chemicals The more likely alternative release scenario for anhydrous ammonia is the shearing of a pipe from the bottom of the ammonia storage tank. Liquid ammonia (37,600 pounds) is released into the diked area. Surface gaseous emissions from the liquid pool are reduced once ammonia flows into a second, smaller below grade containment area. Using the EPA OCA look up tables and stipulated alternative weather conditions (wind speed of 3.0 m/sec and D stability class), potentially impacted public receptors includes the neighboring residential population and employees at the MPC Chemicals, Southwest Polytek, and TRW industrial facilities. There were no active mitigation measures included in modeling of this scenario to limit the exposure distances. Protective barriers were installed to minimize occurrence of this type of incident. The alternative release scenario for ammonium hydroxide (ammonia solution s >= 20% concentration) is a piping failure at the product storage tank which results in the loss of the entire tank contents. Liquid ammonium hydroxide (22,600 pounds) is released to the floor of the ammonia process room. Liquid ammonium hydroxide overflows into the containment sump in the room and to the closed containment tank. The evaporation rate for the solution decreases rapidly after the initial release. Using the EPA OCA look up tables and stipulated alternative weather conditions (wind speed of 3.0 m/sec and D stability class), potentially impacted public receptors are limited to the employees of MPC Chemicals located immediately adjacent to Mesa Facility's south property line. Although vapors inside the room are directed to the Ammonia Vent Scrubber, it was assumed that the scrubber capacity will be exceeded. Removals that would realistically be achieved by the scrubber were not used to limit exposure distances. The selected alternative release scenario for hydrochlori c acid is overflow of the bulk 37% HCl storage tank into the secondary containment area. The operator stops the transfer pump and water is added to minimize acid vapors Chemical release to the atmosphere is not instantaneous but volatilization from the liquid "pool" will occur. Using the EPA OCA look up tables and stipulated alternative weather conditions, it was calculated that HCl vapors potentially impact employees of MPC Chemicals located immediately adjacent to Mesa Facilities south property line. In the modeling of this scenario, it was assumed that all active mitigation systems (engineering and administrative controls) fail. Two alternative release scenarios are presented for hydrofluoric acid (HF); one for 70% HF and a second for 55% HF. Hydrofluoric acid (70%) delivered in bulk tank trucks is immediately diluted to 55% when unloaded. In the first scenario, it is assumed that a 2-inch unloading hose is sheared at the tank truck while unloading the 70% HF. Liquid HF spil ls to the diked storage tank containment area (passive mitigation). The containment area and the unloading bay are under a 40 foot roof. The release is isolated using the emergency button located at front and rear of the trailer. This button closes the unloading valve. Using the EPA OCA look up tables and stipulated alternative weather conditions (wind speed of 3.0 m/sec and D stability class), it was calculated that HF vapors potentially impact employees of MPC Chemicals located immediately adjacent to the south property line and, based on the latest census data available, approximately 24 residential neighbors . No active mitigation measures were considered to limit exposure distances in the modeling of this scenario. The second release scenario for hydrofluoric acid is overflow of the bulk 55% HF storage tank into the secondary containment area. The operator stops the transfer pump and water is added to minimize acid fumes. Chemical release to the atmosphere is not instant aneous but volatilization from the liquid "pool" will occur. Using the EPA OCA look up tables and stipulated alternative weather conditions (wind speed of 3.0 m/sec and D stability class), potentially impacted public receptors is limited to MPC Chemicals located immediately adjacent to the Mesa Facilities south property line. The above information is being used to help us ensure that our Emergency Response Plan and the community emergency response plan address all reasonable contingency cases. There were no listed environmental receptors impacted by any of the alternative release scenarios. GENERAL ACCIDENTAL RELEASE PREVENTION PROGRAM AND CHEMICAL-SPECIFIC PREVENTION STEPS A systematic, proactive approach is taken to prevent accidental releases of hazardous chemicals. To minimize the chance of an release with offsite implications, Arch Chemicals has six layers of safety and environmental protection; our employees, mechanical integrity programs, hazard reviews, process controls , monitoring systems and emergency response. Employees: Well trained employees are our most important resource in operating our facilities and in protecting the community. Mechanical Integrity: This comprehensive inspection and testing program for operating equipment provides more reliable and well-maintained equipment, which greatly reduces the probability of failure. Hazard Reviews: Reviews are conducted on all systems handling hazardous materials. Hazard Reviews identify things that could possibly go wrong so that these situations can be corrected and controlled before an incident occurs. Process Controls: The Mesa Facility has a variety of back-up systems which provide precise control of processes and maintain tight operating parameters. Monitoring Systems: Product sensing detectors immediately identify any potential problems, giving operators an early warning which enables them to provide a quicker and more effective response. Emergency Response: The Mesa Facility Emergen cy Response program is describe in a later Section of this Executive Summary. These individual elements of our prevention program along with the chemical specific prevention actions work together to prevent accidental chemical releases. Our company and our employees are committed to the standard that these management systems set for the way we do business, and we have specific accountabilities and controls to ensure that we are meeting our own high standards for accident prevention. FIVE-YEAR ACCIDENT HISTORY Investigation records are maintained for all incidents that occur at our facility. We have had seven (7) accidental releases of hydrofluoric acid in the last three years that require reporting under the RMP rule. The largest of these experienced since the 1996 start up of the facility was a 500 pound release of 55% liquid hydrofluoric acid. As a result of these releases, injuries that required medical attention occurred to six on-site employees and one contract employee. None of the injuries had any long term effects on the individual. None of the incidents had an off-site impact. For each of these incidents, we have conducted formal incident investigations to identify and correct the root causes of the events. EMERGENCY RESPONSE PROGRAM In the unlikely event of a major spill or release, the Site Emergency Response Teams goal is to contain any releases and to correct the problem before any off site impact occurs. Our emergency response plan (ERP) addresses the various federal, state, and local regulatory requirements for emergency planning, providing the essential elements for effectively protecting workers, the public, and the environment during emergency situations. To assist us in the event of an emergency, local area emergency responders have been provided with our ERP. Facility Response Team members are on site 24 hours a day, 365 days a year. These highly trained employees are experienced in Chemical Emergency Response, as well as Advan ced First Aid. On site drills and training are conducted on a regular basis. The City of Mesa Fire Department is responsible for notifying the public of any release which has potential off-site impacts. The Arch Chemicals Mesa Facility is evaluating alert system options to assist in improving the timeliness of the current notification process. PLANNED CHANGES TO IMPROVE SAFETY Planned facility improvements whose implementation will help prevent accidental chemical releases from occurring and adversely affecting our employees, the public, and the environment include: (1) Installation of a water deluge system over the bulk tanks/bulk unloading area to maximize our ability to contain acid vapors from potential releases within the area. (2) Providing a 'more timely' alert system for neighboring residents than the current City door to door notification process. In addition, plans are being made to initiate regular joint onsite emergency drills/training between the City of Mesa Fire D epartment and Hazmat Teams and Arch Chemicals Emergency Response Team members. |