Hill Brothers Chemical Co. - Phoenix facility - Executive Summary |
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Hill Brothers Chemical Co. (HBC) developed this document to meet the requirements for a Program 3, Risk Management Plan (RMP) under the Accidental Release Prevention Program, Clean Air Act Amendments of 1990 for their facility located at 4450 North 42nd Avenue, Phoenix, Arizona. The RMP applies to the following processes: 7 Anhydrous Ammonia Fill 7 Anhydrous Ammonia Storage 7 Chlorine Fill/Bleach 7 Chlorine in Warehouse 7 Sulfur Dioxide in Warehouse This RMP was prepared in accordance with the US Environmental Protection Agency (USEPA) requirements in 40 Code of Federal Regulations (CFR) Part 68. HBC prepared this RMP in conjunction with the Arizona branch of EMCON Environmental Associates (EMCON). The HBC Accidental Release Prevention & Emergency Response Policies The HBCs policy is to conduct all operations in a safe and conscientious manner to prevent accidental releases of any hazardous material, including substances regulated through the Federal Accidental Release Preventio n Program. HBC trains its employees at this facility to properly handle, store, and use hazardous materials to minimize the possibility of adversely affecting its worker's health, the workplace, the public, and the environment. In the event of an emergency, HBC will contact the Phoenix Fire Department to respond. A designated emergency contact for the plant initiates emergency notifications. All employees are trained in the proper procedures and their appropriate role in an emergency. The Phoenix plant maintains a highly cooperative relationship with the Phoenix Fire Department to ensure a full understanding of the processes and emergency response and evacuation procedures related to regulated substances. General Description of Regulated Substances and Stationary Source The HBC's Phoenix facility is located at 4450 North 42nd Avenue, Phoenix, Arizona. The Phoenix operations relating to this RMP are described briefly below. Anhydrous Ammonia Fill. Anhydrous ammonia liquefied u nder pressure is received at the facility in large containers and repackaged into smaller containers for subsequent delivery to HBC customers. Until delivery, the repackaged ammonia is stored at this process area. Anhydrous Ammonia Storage. Anhydrous ammonia is received at the facility in large containers and transferred into an on-site storage container. This material is subsequently transferred to smaller containers for subsequent delivery to HBC customers. Chlorine Fill/Bleach. Chlorine liquefied under pressure is received and stored on-site in large containers. The chlorine is transferred to smaller containers for subsequent delivery to HBC customers. Chlorine is also used to make bleach solution which is then packaged and delivered to HBC customers. Chlorine in Warehouse. The smaller chlorine containers that are filled on site are stored in the warehouse until they are delivered to customers. Sulfur Dioxide in Warehouse. HBC receives sulfur dioxide liquefied under pres sure in containers from a supplier. These containers are stored in the warehouse until they are delivered to customers. No repackaging or processing occurs with the sulfur dioxide containers. The North American Industrial Classification System (NAICS) code for the two ammonia processes and the Chlorine Fill/Bleach process is 325188, All Other Basic Inorganic Chemical and Allied Products Wholesalers. The NAICS code for the chlorine and sulfur dioxide warehouse storage process is 42269, Other Chemical and Allied Products Wholesalers. Anhydrous ammonia is a colorless gas or liquid with a sharp, irritating odor. Chlorine is a dense, greenish-yellow gas with a pungent, irritating odor. Sulfur dioxide is colorless gas or liquid with a sharp, pungent odor. The vessels received at the facility, the on-site storage vessel for ammonia, and the small vessels which store repackaged materials on-site are metal vessels designed to Department of Transportation standards. Other process vess els are designed to American Society of Mechanical Engineers standards. Each metal cylinder and ton container has a steel valve protection cap which covers the vessel valve or valves. These steel protective caps are never removed from the container unless the container is being filled. The warehouse where the chlorine and sulfur dioxide containers are stored is a concrete building with a metal roof. A fire suppression system is present in the building which consists of automatic sprinklers which are activated in case of a fire. Off-Site Consequence Analyses Results The RMP Program requires the evaluation of an accidental release of the regulated substance from the process being considered. In its General Guidance for Risk Management Programs, July 1998, USEPA states that it should be kept in mind that the results obtained from modeling release scenarios should not be considered to predict the likely results of an accidental release. The assumptions made in the computer models are very conservative and tend to overpredict the impact from an accidental release. The results from such models have a high degree of uncertainty and should be viewed as providing a basis for discussion, rather than hard predictions. As required by USEPA for the RMP, two types of release scenarios were assessed for the processes at the Phoenix facility. The first scenario is a worst-case release which is mandated by USEPA to be the release of the largest quantity of a regulated substance that results in the greatest distance from the point of release to a specified endpoint (40CFR'68.3). The second scenario is an alternative release scenario which is more likely to occur than the worst-case scenario and reaches an endpoint offsite. Details of these two types of scenarios are presented below. For anhydrous ammonia, the specified endpoint is a concentration of 0.14 milligrams of ammonia per liter of air (mg/L). For chlorine, the specified endpoint is a concentration of 0 .0087 mg/L. For sulfur dioxide, the specified endpoint is a concentration of 0.0078 mg/L. These endpoint concentrations are intended to be conservative and protective. They are concentrations below which it is believed nearly all individuals could be exposed for up to one hour without any serious health effects. Worst-Case Release Scenario USEPA requires that the worst-case release scenario be the release of the entire contents of the single largest vessel containing a regulated substance that reaches the greatest distance to the endpoint. Thus, even for multiple processes with different regulated substances, only one worst-case release scenario is required. USEPAs RMP*CompT model was used as the method for estimating the distance to the endpoint. The RMP*CompT default values for release duration, wind speed, and atmospheric stability class were utilized for this modeling. These default values are very conservative in predicting the distance to the endpoint. The worst-cas e release scenario was designated as the release of 180,000 pounds of chlorine gas from a 90-ton railcar at the facility. No other containers are affected by this release scenario. The distance from the site of the release to the endpoint extended beyond the boundaries of the Phoenix facility. Public receptors are located within this distance to the endpoint. Alternative Release Scenario Alternative release scenarios gives us an opportunity to present potential release impacts which are more credible than a worst-case scenario. However, it should be noted that given the safety and accident prevention mechanisms in place at Phoenix, these alternative release scenarios are not considered to be highly likely. USEPA requires that one alternative release scenario be reported for each regulated substance at a facility. In this case a total of three alternative release scenarios were evaluated for the facility; one each for anhydrous ammonia, chlorine, and sulfur dioxide. The RMP*Com pT default values for release duration, wind speed, and atmospheric stability class were utilized for this modeling. Once again, these values are very conservative. For the anhydrous ammonia alternative release scenario it was assumed that a hydrostat relief valve on a process pipe failed. This process piping is located outside. Such an equipment failure would allow liquid anhydrous ammonia to leak from the pipe, pool on the ground, and evaporate into the air. Ammonia has a highly distinctive odor and it was assumed the process operator would detect the leak and close the valve supplying the pipe within two minutes. A total of 950 pounds of anhydrous ammonia was estimated to be released from the process. The distance from the site of the release to the endpoint extends beyond the boundaries of the Phoenix facility. Public receptors are located within this distance to the endpoint. For the chlorine alternative release scenario it was assumed that polyvinyl chloride (PVC) pipe carrying chlorine gas ruptured. This process piping is located outside. Such an equipment failure would release chlorine gas directly into the air. Chlorine sensors in the area would alert the operator that a release had occurred. It was conservatively estimated that two minutes before the operator could close the valve to the ruptured piping. A total of 400 pounds of chlorine gas was estimated to be released from the process. The distance from the site of the release to the endpoint extends beyond the boundaries of the Phoenix facility. Public receptors are located within this distance to the endpoint. For the sulfur dioxide alternative release scenario it was assumed that a one-ton vessel stored in the warehouse developed a leak from a faulty valve mechanism. Under this scenario the escaping sulfur dioxide gas cools rapidly as it expands from the container thus eventually freezing and closing the source of the leak. In the presence of ambient temperature on the outside of the container, the frozen sulfur dioxide will eventually melt and allow additional sulfur dioxide gas to escape until the cycle repeats. It is estimated that this intermittent release mechanism would allow a total of approximately 2,000 pounds of sulfur dioxide gas to be released into the interior of the warehouse. The gas would then exit the building through doorways to the outside air. HBC staff at the Phoenix facility would evacuate the immediate area and call the Phoenix Fire Department to respond. It is estimated that 26 minutes would transpire between the release starting and the one-ton container being completely emptied. The distance from the site of the release to the endpoint extends beyond the boundaries of the Phoenix facility. Public receptors are located within this distance to the endpoint. Summary of the General Accidental Release Prevention Program & Chemical Specific Prevention Steps HBC's release prevention program applies to each covered process and complies with Federal Accidental Release Prevention requirements. HBC's prevention program emphasizes thorough training for its employees in hazard communication; proper handling, transfer, used, and storage methods; and emergency response procedures. HBC's standard operating procedures include diligent observation of process vessels, valves, and other equipment; and safe movement and storage of vessels. The vessels received at the facility, the on-site storage vessel for ammonia, and the small vessels which store repackaged materials on-site are metal vessels designed to Department of Transportation standards. Other process vessels are designed to American Society of Mechanical Engineers standards. Each metal cylinder and ton container has a steel valve protection cap which covers the vessel valve or valves. These steel protective caps are never removed from the container unless the container is being filled. The warehouse where the chlorine and sulfur dioxide containers are stored is a concrete building with a metal roof. A fire suppression system is present in the building which consists of automatic sprinklers which are activated in case of a fire. Summary of Five-Year Accident History On the basis of a review with HBC during preparation of this RMP, there have been no accidents or accidental releases involving anhydrous ammonia, chlorine, or sulfur dioxide at the Phoenix facility in the last five years. Summary of the Emergency Response Program HBC's Phoenix facility has a written Emergency Response Plan. The focus of the plan is to protect the public, protect employees, protect public property, and protect HBC facilities. Immediately after discovering a release, Phoenix personnel are instructed to notify the Phoenix Fire Department for initial response and evacuate the area affected by the release. The Phoenix Fire Department will be the primary responder to a release. Planned Changes to Improve Safety The HBC Phoenix facility is continually evalu ating ways to improve safety at the site. HBC trains its employees at this facility to properly handle, store, and use hazardous materials to minimize the possibility of adversely affecting its worker's health, the workplace, the public, and the environment. |