MEMC Southwest, Inc. - Executive Summary |
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MEMC Southwest - Risk Management Plan Executive Summary June, 1999 Introduction MEMC Southwest, Inc (MEMCSW) is a joint venture with Texas Instruments, Inc, located in Sherman, Texas. MEMC Southwest is an operating subsidiary of MEMC Electronic Materials, Inc, headquartered in St. Peters, Missouri. Its operations are dedicated to the manufacture of silicon wafers for the electronic industry. MEMC Southwest employs 1250 people, of which 585 are associated with the operation to which this RMP applies. MEMCSW is submitting this Risk Management Plan (RMP) in accordance with section 112(r) of the federal Clean Air Act for only two regulated substances: Trichlorosilane and anhydrous Hydrogen Chloride. The requirement applies only to the operation located at 6416 Highway 75 South, Sherman, Texas. Accidental Release and Emergency Response Policies MEMCSW's practice of chemical safety is reflected in the MEMC corporate Environmental, Safety and Health Policy: "MEMC Electronic Materials, Inc will strive to achieve an injury-free and healthful workplace for our employees, ensure the safety of our community neighbors, and work toward zero-effect on the surrounding environment at each of our operating locations worldwide. It is MEMCSW's policy to operate in a manner that complies with all applicable federal, state and local environmental, safety and health requirements. We are committed to operating the plant and maintaining all of our processes in a safe and responsible manner. We use a combination of engineering controls, prevention and emergency response programs to help ensure the safety of our employees, of the community to which we belong, and to ensure the protection of the environment. Facility and Regulated Substances MEMCSW produces silicon wafers from ultra-pure sand. The process begins with conversion of sand into silicon. The facility first uses silicon as a raw material where it is further converted into cylindrical silicon ingots. The ingots are then sliced into thin wafers. The wafers then undergo many steps to polish the wafer to customer specifications. Once the wafer is polished, it may receive a special coating, known as an 'epitaxial layer', or 'EPI' layer. This layer provides certain electronic characteristics. It represents one of many wafer products produced at this facility. The application of the EPI layer is where the regulated substances are used. Trichlorosilane is stored in volumes up to 56,000 pounds in one tank, located above ground. The anhydrous hydrogen chloride is stored in one tube trailer, holding seven tubes containing 3000 pounds each, totalling up to 21,000 pounds. Worst Case and Alternative Release Scenarios The RMP rule requires that we provide information about the worst-case and alternative release scenarios for our facility. The following are summaries of these scenarios: The worst case chemical release scenario was modeled using the U.S. Environmental Protection Agency's 'RMP*Comp' model for a h ypothetical one-time release of the total quantity of hazardous substances. For trichlorosilane, the scenario involves the release of the 56,000 pounds from the storage tank. The entire release would occur within ten minutes. The results of this event are listed, per the assumptions accounted for in the modeling exercise, and are contained in this RMP. For anydrous hydrogen chloride, the scenario involves a similar scenario where all 21,000 pounds are released from the tube trailer. This material is not reactive with air. The modeling results are also listed in the RMP. During our modeling efforts, we assumed no mitigating circumstances or operational controls to minimize the release, as per EPA guidance. The product of hydrolysis for trichlorosilane is hydrogen chloride, of which, the release scenario was modeled per this end product. The alternative release scenarios included a longer duration release of 60 minutes, as would be characteristic of a smaller leak from the storage tan ks. Of the hypothetical scenarios, this was a more realistic scenario because of the consideration for detailed safe handling procedures already in place. General Release Prevention Program We take a systematic, proactive approach to preventing accidental releases of hazardous materials. Our process management systems address each of the key features of successful prevention programs including: * Process Safety Information * Process Hazard Analysis * Operating Procedures * Employee Training * Preventative Maintenance and Mechanical Integrity * Management of Change * Pre-startup Reviews * Compliance Audits * Incident Investigation * Employee Participation * Permit to Work Systems including Hot Work Permits * Contractor Qualification and Safety Programs As part of out prevention efforts, we have implemented the following chemical-specific prevention factors: * All changes to the process systems must be reviewed and approved by specialists in engineering, process technology, op erations, maintenance, and environmental, safety and health. * All process systems are included in comprehensive, documented preventative maintenance and mechanical integrity programs. * All employees must successfully complete comprehensive training programs to be qualified to work with the related processes and equipment. * All processes are connected to scrubber systems so that process upsets, should they occur, do not cause material to discharge directly to the atmosphere. Five-Year Accident History We keep records for all significant incidents that occur at our facility. For each incident we conduct formal investigations and identify and correct root causes of the events. We have had no significant release of trichlorosilane or anhydrous hydrogen chloride since the start-up of the EPI operation in 1984. Emergency Response Program In the event of an emergency involving any of the hazardous material at MEMCSW, the response would be handled through an integrated response invol ving on-site and off-site resources. The plant maintains a trained hazardous materials response team. The team receives 40 hours of training when they join the team, with on-going refresher training. Other employees trained in process specifics are available as needed. The Sherman Fire Department is available to respond to emergencies. Planned Changes to Improve Safety Due to the safe operating history of the plant and consistent process application, no new safety systems are scheduled to be implemented. However, the plant undergoes routine reviews of the existing safety systems. Following is a list of routine safety review activities: * Conduct review of work procedures and system operations every three and five years, in accordance with the federal Process Safety Management rules. * Continual process hazard analysis to identify potential problems and implement changes * Continuous systems maintenance. * Auditing and inspecting all systems to ensure Y2K compliance |