Lenzing Fibers Corporation - Executive Summary |
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Lenzing Fibers Coproration manufactures rayon fiber in Lowland, Tennessee (Hamblen County). The basic raw materials used in the rayon production process are cellulose, sodium hydroxide, and carbon disulfide (CS2). CS2, which is an RMP regulated substance, is delivered to the plant via railcars and unloaded to one of six 28,500-gallon storage tanks. All six of the storage tanks are enclosed in a single water bath (an open concrete tank filled with water) for containment. From the storage tanks, the CS2 is piped to the xanthation process where it is used in the production of rayon fiber. Process and sanitary wastewater from the Lenzing production facilities and the rest of the Lowland site are treated at a treatment facility on-site. Chlorine, an RMP regulated substance, is utilized as a disinfectant. Chlorine is a gas at ambient conditions, but is delivered to the plant in one-ton cylinders as a pressurized-liquid gas. Two (2) one-ton cylinders are kept on-site at a time and bot h are tied into the treatment system. The chlorine cylinders are housed in a concrete block building that is equipped with a chlorine detection and alarm system. A five-year acident history, which includes the period from December 1994 through November 1999, is included as part of this submittal. Two accidental releases that qualify for inclusion in the accident history occurred during the period. Both accidents were exlposions involving small quantities of carbon disulfide and are included in the listing due to on-site property damage. A design flaw, which has since been identified and corrected, was responsible for the accidents. The RMP rule defines the worst-case release as "the release of the largest quantity of a regulated substance from a vessel or a process line failure that results in the greatest distance to an endpoint" (40 CFR Part 68.3). The worst-case release scenario (WCS) for the Lenzing facility considers the catastrophic failure of one of the six 28,500-gallo n carbon disulfide storage tanks. In accordance with EPA guidance, it is assumed that the contents of the tank are spilled instantaneously and then evaporate to the atmosphere. The containment walls surrounding the CS2 tanks meet the EPA criteria for passive mitigation and are therefore reflected in the RMP*Comp analysis. For the WCS, it is conservatively assumed that there is no water in the diked area covering the tanks. Using the site specific parameters discussed above and the standard parameters for a WCS defined by EPA, RMP*Comp predicts a distance to the toxic endpoint of five (5) miles. The RMP rule defines the alternative release scenarios (ARS) as release events that are more likely than the WCS.The rule also dictates that the ARS should result in off site consequences. Lenzing performed one ARS for each covered process - one involving CS2 and one involving chlorine. The ARS for the rayon production process considers a piping/vessel leak during railcar unloadin g that results in the release of the total contents of a car (18,000 gallons) over a 60-minute period. The area around the railcar unloading station is graded such that a release would drain to a containment sump filled with water thereby reducing the instataneous evaporation rate of CS2 to the atmosphere. RMP*Comp modeling predicts a four-tenths (0.4) mile radius to the toxic endpoint for this scenario. The ARS for the wastewater treatment facility considers the failure of process piping resulting in the release of 2,000 pounds of chlorine over a 60-minute period. While it is unlikely an event such as this would occur considering the chlorine detection and alarm system Lenzing has in place, the scenario was considered for emergency planning purposes. RMP*Comp predicts a distance to the toxic endpoint of (0.3) miles for this release scenario. CS2 and chlorine are regulated substances under both the RMP and process safety management (PSM) rules. Therefore Lenzing already had an a ctive release prevention plan in-place prior to RMP. Key components of the accident prevention program include: high level training for operators, a preventive maintenance program, technological process and safety equipment, effective operating procedures, and a routine inspection program. Lenzing has in-place a written emergency response and a trained emergency response team. While Lenzing coordinates with the local emergency responders, the facility maintains the resources and the majority of the responsibility for responding to a release at the facility. In the process of implementing the risk management program, Lenzing evaluated the facility's chlorine storage and handling procedures and decided to reduce the maximum quantity of chlorine kept on site from four one-ton cylinders to two one-ton cylinders. This will allow Lenzing to keep all of the chlorine on site in an enclosed building with a chlorine detection and alarm system. Lenzing maintains an active process safety ma nagement team to continually make safety improvements such as this one. |