ASARCO Inc./ Amarillo Copper Refinery - Executive Summary |
|
ASARCO Incorporated (Asarco) owns and operates a copper refinery and precious metals recovery plant at its Amarillo Copper Refinery (ACR), in Potter County, Amarillo, Texas. Through the copper refining process, impurities such as gold, silver, nickel sulfate, and other by-products are recovered. The process consists of electrolytic refining in which copper is separated from other metals by passing an electric current through a solution of copper sulfate and sulfuric acid. Further processing steps lead to the recovery and refinement of other metals. Section 112(r) of the Clean Air Act applies to ACR because the plant handles and stores propane , hydrochloric acid (HCl) and sulfur dioxide (SO2) in excess of threshold quantities. Two requirements of this section specifically apply to operations at the plant: 1. Purpose and General Duty Clause - The essence of the general duty clause, '112(r)(1), is that an owner/operator that stores and uses hazardous chemicals in any quantity has a fundamental obligation to ensure a safe operation and to have plans in place in the event of an accident to appropriately manage the situation. Asarco is committed to ensuring the safe operation of ACR, as well as all of its other operations, to ensure a safe workplace for our employees and a safe location for our neighbors in the community. Asarco, therefore, has procedures in place to prevent accidents and is committed to emergency preparedness both for the plant and for the community by coordinating with the Amarillo/Potter/Randall Local Emergency Planning Committee (LEPC). 2. Risk Management Plan - The copper refinery and precious metals recovery plant at ACR involves the handling and storage of three chemicals in excess of thresholds specified in '112(r). Even prior to the promulgation of '112(r), Asarco management has been very aware of the potential hazards posed by the handling and storage of propane, hydrochloric acid, and sulfur dioxide. Programs have been established to prevent accidental releases and to train personnel for emergency response in the event of a release, including maintaining a trained onsite fire brigade. To date, no accidents with offsite impacts have occurred at these facilities. In addition to the above Clean Air Act requirements, Asarco is in compliance with the OSHA PSM, EPA SPCC, OSHA HAZWOPER, EPCRA, and EPA RCRA Contingency Planning requirements. Asarco has also conducted a process hazard analysis on the sulfur dioxide process, the only PSM-covered process at ACR. For planning purposes, Asarco has considered the impact of five potential "worst case" accidents involving the three RMP-covered chemicals. These worst case scenarios are defined as follows: 7 Process (1): Hydrochloric Acid Railcar Storage System - Assumes the entire contents (210,000 lbs) of a railcar of HCl at the marshaling yard are released in 10 minutes reaching a potential impact distance of 6.2 miles in any direction. No passive mitigation was considered. This worst-case release would reach offsite receptors. It should be emphasized that the probability of the worst-case catastrophic event evaluated in this report is extremely remote - far less than natural catastrophes such as tornadoes and floods that could produce much more severe and extensive damage and injury. 7 Process (2): Hydrochloric Storage & Process System - Assumes the entire contents (340,000 lbs) of the two HCl storage tanks are released in 10 minutes reaching a potential impact distance of 3.4 miles in any direction. This worst-case release would reach offsite receptors. The double-containment dike around the storage tanks was considered as passive mitigation, since the liquid would be released into the diked area limiting the surface area for evaporation, and thus limiting the impact to people and the environment. It should be emphasized that the probability of the worst-case catastrophic event evaluated in this report is extremely remote - far less than natural cata strophes such as tornadoes and floods that could produce much more severe and extensive damage and injury. 7 Process (3): Propane System - Assumes the total quantity in the propane storage tank (17,000 lbs) is instantaneously released forming a vapor cloud that is assumed to detonate. No passive mitigation was considered. The distance to the one-pound-per-square-inch (1-psi) overpressure endpoint is calculated to be 0.2 miles, which does not reach off-site receptors. 7 Process (4): Sulfur Dioxide Railcar Storage System - Assumes the entire contents (180,000 lbs) of sulfur dioxide are release in 10 minutes from a railcar at the marshaling yard reaching a potential impact distance of 25 miles or greater in any direction. No passive mitigation considered. This worst-case release would reach offsite receptors. It should be emphasized that the probability of the worst-case catastrophic event evaluated in this report is extremely remote - far less than natural catastrophes such as torna does and floods that could produce much more severe and extensive damage and injury. 7 Process (5): Sulfur Dioxide Storage & Process System - Assumes the entire contents (310,000 lbs) of the storage tank are released in 10 minutes reaching a potential impact distance of 25 miles or greater in any direction. No passive mitigation considered. This worst-case release would reach offsite receptors. It should be emphasized that the probability of the worst-case catastrophic event evaluated in this report is extremely remote - far less than natural catastrophes such as tornadoes and floods that could produce much more severe and extensive damage and injury. Asarco also considered the impact of more likely releases. Of the five processes for which worst-case scenarios were evaluated, alternate release analyses were performed for Processes (1), (4), and (5). The potential impact radius for the worst-case scenario for Process (2) falls totally within that for Process (1), making it unnecess ary to report this scenario or proceed with an alternative release scenario. The worst-case release for Process (3), involving propane, would have no off-site impacts and meets the requirements of Program 1; therefore, it does not require an alternative release scenario analysis. The three alternative release scenarios are characterized as follows: 7 Process (1): Hydrochloric Acid Railcar Storage System - An accidental and unmitigated liquid release of hydrochloric acid from a 1/2-inch hole in the side of the railcar that is sided on the railroad tracks in the marshaling yard, resulting in 120,000 pounds being released over a period of 16 hours. The 16-hour time interval is based on the conservative assumption that the release, being remote from operations, would go unnoticed from the end of one shift (3 p.m.) to the start of the next (7 a.m.). The duration of this release could be less if it were to occur during the daytime when it could be noticed sooner. Using RMP*Comp, the im pact distance of this release was calculated to be 0.8 miles, which could potentially have offsite impacts. 7 Process (4): Sulfur Dioxide Railcar Storage System - An accidental toxic gas release of up to 17,000 pounds of sulfur dioxide from a 1/2-inch hole in the railcar that is sided on the railroad tracks in the marshaling yard. The release is estimated to occur over a 16-hour time interval based on the conservative assumption that the release, being remote from operations, would go unnoticed from the end of one shift (3 p.m.) to the start of the next (7 a.m.). The duration of this release could be less if it were to occur during the daytime when it could be noticed sooner. Using RMP*Comp, the impact distance of this release was calculated to be 1.5 miles, which could potentially have offsite impacts. 7 Process (5): Sulfur Dioxide Storage & Process System - An accidental release of up to 140,000 pounds of sulfur dioxide from a sheared 2-inch pipe during transfer of sulfur dioxide from the storage tank to the process area. Although liquified under pressure in the pipe, the sulfur dioxide is assumed to vaporize instantaneously upon release from the pipe. The duration of this release is approximately 30 minutes, based on the time needed for personnel to stop the release by closing the manual shut-off valve at the storage tank. Using RMP*Comp, the impact distance of this release was calculated to be 3.3 miles, which could potentially have offsite impacts. Asarco has implemented safety precautions and procedures designed to prevent and mitigate catastrophic releases. Asarco has active operating, maintenance, training, and inspection procedures; a trained fire brigade; and an evacuation plan for each area. In addition, Asarco has coordinated emergency response with the LEPC. Asarco's management is committed to the following: - Preventing accidents; - Training our employees in correct response procedures in the event of an accident; - Participating in communit y emergency preparedness; - Addressing any citizen concerns by fully explaining potential hazards associated with Asarco operations and all steps being taken to prevent and mitigate accidents; and - Being a good corporate citizen of Potter County. With these objectives in mind, this Risk Management Plan has been developed to provide information about Asarco's management of the risks associated with operating the copper refinery and precious metals recovery plant at ACR. Most important, we stress our commitment to ensuring a safe operation for our employees, our visitors, and our community. |