Roll Grain & Feed Center - Executive Summary

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Shawnee Milling Company operates rural feed stores offering anhydrous ammonia to local farmers.  The Roll Grain and Feed Store is located well outside the outskirts of Cheyenne, Oklahoma in an entirely remote rural exposure.  The maximum quantity of this toxic unrefrigerated liquid at any one time is 50,000 pounds.  For approximately 3-4 months of the year, the aveage on-hand quantity is less than 10,000 pounds. 
The company ensures that the tank and its components are regularly mainteained by either trained employees or qualified contractors.  The facility is regularly inspected by both employees, its insurance carrier, and the State of Oklahoma Department of Agriculture. 
This facilty would hav a maximum of 50,000 pounds of anhydrous ammonia onsite at its peak sales periods.  Administrative operating procedure limti tank storage to less than 85% of capacity. 
The worst case scenario is structural damage to the bulk storage tank containig, at peak operating periods, up to 50,000 pound 
s of NH3.  Failure would result in a near-full release of ammonia within 10 minutes in a rural environment.  The toxic endpoint has been calcualted to be 4 miles from the tank at which point it would be dispersed enough to no longer pose a hazard to the public.  Public receptors includeresidences and a national grasslands area open during seasonal hunting periods. There are no other commerical or environmental receptors within the range to the toxic endpoint. 
The more probable alternative accidental release would involve a transfer hose failure that could potentially result in up to 100 pounds release of anhydrous ammonia before an emergency shutoff valve could be activated.  The toxic endpont would be limited to 0.2 miles which would expose less than 1/2 dozen people.
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