ZEELAND FARM SERVICES - Executive Summary |
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Executive Summary Zeeland Farm Services is an anhydrous ammonia fertilizer dealer. They have two 10,000 gallon tanks on site for anhydrous ammonia storage. Due to chemical parameters and administrative controls, these tanks are only filled to 85%. At this level, each tank holds approximately 68,000 pounds of anhydrous ammonia. The anhydrous ammonia is liquefied by pressure (140psi). The storage tanks are surrounded by a 10 foot high earthen berm. There are also twenty small nurse tanks on site. Each one of these holds approximately 4,000 pounds of anhydrous ammonia. The nurse tanks are also subject to the 85% fill condition. Zeeland has an Emergency Response Plan in place and has completed a process hazard assessment of their anhydrous ammonia system. The system includes all of the safety features as required by code and rule. Worst Case Release Scenario The worst case release scenario for anhydrous ammonia was calculated as the loss of the largest, single storage tank in a ccordance with the definition provided in the Environmental Protection Agency guidance for RMP development. Only passive control systems were taken into consideration. The conditions of the scenario, including release time and weather conditions are those provided in the EPA Off-Site Consequence Analysis Guidance. Determination of the area of potential impact was determined using RMP*Comp, modeling software developed by the EPA. The distance to the toxic endpoint was calculated to be 4.7 miles. Approximately, 4500 people would be affected by a release of this size. Sensitive receptors include a hospital and 11 schools. Alternative Release Scenario The alternative release scenario is, by definition, a more likely release scenario than the worst case. Engineered controls, such as detection systems and alarms, are considered in the analysis. The type of system failure selected for the alternative release was the loss of anhydrous ammonia due to a break in the transfer hose lead ing from a large storage tank to a nurse tank. Each nurse tank holds approximately 4,000 pounds and takes 20 minutes to fill. This gives a fill rate of approximately 200 pounds per minute. The anhydrous ammonia would leak from a 1/2" diameter opening. The leak would continue until noticed by personnel supervising the anhydrous ammonia transfer and the valves on the tanks could be closed. Because someone is always present during the transfer of ammonia between tanks, the time for the response was estimated at 5 minutes. RMP*Comp was also used to model this scenario. In this amount of time, 2,960 pounds of anhydrous ammonia would be released. The distance to the toxic endpoint is 0.5 miles. Approximately, 1,500 people would be affected by a release of this size. Process Hazard Assessment A process hazard assessment was performed of the anhydrous ammonia system beginning with the filling of the storage tank. A combination checklist and modified "What if" type of analysis was used. General questions regarding the storage and use areas as well as practices and protocols associated with the management of the anhydrous ammonia system were answered. Following the checklist, each valve, line and piece of equipment in the system was assessed using system flow diagrams. The valves and other points in the systems where anhydrous ammonia could be released are numbered on the flow diagrams. The assessment is formatted in accordance with those numbers. Compliance with code requirements, considerations of potential failure, maintenance and inspection concerns, and standard operating procedures were reviewed for each point in the system. Prevention System The Plant has an operation, maintenance and inspection system designed to review each element of the anhydrous ammonia system routinely. Personnel receive training before being allowed to work on the system. Personnel are trained routinely on safety concerns and general operation procedures as well as emergen cy procedures. All equipment is inspected each spring before the system is first used and then daily during the season. There are standard operating procedures (SOPs) for filling the storage tanks, filling the nurse tanks, disconnecting the nurse tanks and disconnecting the trucks from the storage tanks. The SOPs are written and posted in the appropriate areas. Accident History The plant has had no releases as defined in 40 CFR Part 68.3 over the last five years. |