Witco Corporation, Marshall Plant - Executive Summary |
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Attached summary as word.doc WITCO CORPORATION, MARSHALL PLANT RISK MANAGEMENT PLAN EXECUTIVE SUMMARY 1. Introduction and Background The Accidental Release Prevention (ARP) requirements mandated in Section 112r of the 1990 Clean Air Act Amendments were promulgated by the Environmental Protection Agency (EPA) on June 26, 1996. These requirements are codified in 40 CFR 68, Subparts A through H. Under the ARP program, processes with chemical quantities on site exceeding the listed threshold quantities have applicable requirements. The only regulated substance above threshold limits established by the EPA that is handled at the Marshall facility is phosphorous trichloride. Phosphorous trichloride is stored in one tank and used as a raw material in the production process. The stationary source covered by the Risk Management Plan is the storage tank, T-20. Practices and procedures are in place to safely store and handle phosphorous trichloride. 2. Description of the Stationary Sou rce and Regulated Substances Witco's Marshall plant has been in operation at 710 Bussey Road in Marshall Texas since 1968. The facility is located in Harrison County. The plant is a producer of specialty polymer additives including organic peroxides. The Marshall Plant is committed to ensure the continued safety of its employees and the community by implementation of the best safety management practices. These practices concentrate on accident prevention and preparedness to prevent incidents and to minimize the effects of any accident that may occur. These practices apply to all chemicals stored, handled, and produced at the plant. The 83 employees of the Marshall plant are committed to the safety of the surrounding community. 3. Worst Case release scenario and alternate release scenario Risk Management Planning requires development of a worst-case scenario and an alternative release scenario for phosphorous trichloride. A worst-case scenario is defined as the complete rele ase of the largest inventory of the chemical over a 10 minute period under weather conditions that would allow the chemical to travel as far as possible at ground level. It also assumes that none of the site's mechanical controls or safety systems are operational. Although this scenario is highly unlikely to occur, it is required for planning purposes. The alternative release scenario is one that more closely simulates a potential release. Although a large release described in this scenario has never occurred at the facility, for planning purposes in conjunction with local agencies, the alternative release scenario would be used as a realistic possibility. Worst- Case Toxic Release Scenario- The worst-case release scenario is considered as a catastrophic failure of the phosphorous trichloride storage tank into the diked area. Assuming all safety systems fail in the worst possible weather conditions, using EPA mandate criteria, the off site impact is depicted in Table 1 as calcu lated by the Safer Trace program. Table 1 Distance to Endpoint for Toxic Worst-case scenario Chemical Hypothetical Release Scenario Mitigating Measures Largest Quantity on Site (lbs.) Distance to Toxic Endpoint phosphorous trichloride Tank Failure None 62800 1.68 miles However, this scenario is highly unlikely to occur, as the tank is provided with a rupture disk should fire threaten to catastrophically rupture the vessel. The tank is also contained within an acid brick lined secondary containment dike with fire monitors available to neutralize vapors in the event of a release. Administrative procedures are in place to monitor tank levels and containment for releases. Alternate Toxic Release Scenario- Alternate release scenarios are those which are more likely to occur than the worst-case release scenario. Alternate release scenarios reported are those that lead to concentrations above the endpoint specified by EPA, which extend past the facility's fenceline. The facility has u tilized EPA's default modeling parameters, and assumed releases at ground level. All modeling was performed utilizing the Safer Trace model. Table 2 depicts the alternate release case. Table 2 Distance to Endpoint for Toxic Alternate-case Scenario Chemical Release Scenario Release Amount (lbs.) Mitigating Measures Distance to Endpoint phosphorous trichloride Pipe leak 21720 lbs. over 30 minutes Dikes, drains, covered roof 0.40 miles Active mitigation consists of water sprays outside the dike to react with vapors and possible use of vapor-suppression foam to reduce evaporation of the liquid. Active mitigation also involves collection of spilled liquid into closed containers to prevent further evaporation. General Accidental Release Prevention Program General accidental release prevention is a part of the Marshall Plant's program for all chemicals stored and handled at the facility. Emphasis is on release prevention through equipment inspection and frequent observation of equipment for early detection and control of any leaks found. The facility prevention program is detailed in the Emergency Response Plan Manual that includes Emergency Response, Spill Prevention Control and Containment, the RCRA Contingency Plan, and Preparedness and Prevention Requirements. Five year accident history. There have been no defined accidents with phosphorous trichloride at this site. The site has not had a significant accident or release involving phosphorous trichloride within the last five years. The emergency response program. A plant-wide emergency response program is in place at the Marshall facility. This plan integrates OSHA requirements with emergency response, spill containment and control, and measures to prevent storm water contamination at the Plant. The plan includes specific measures for phosphorous trichloride in addition to plans for all chemicals stored and handled at the facility. Planned changes to improve safety. The facility is committed t o continually improving safety for all materials at the plant with emphasis on phosphorous trichloride. The program will utilize employee participation, process hazard reviews, and information obtained from incident investigations and other sources. |