DeBruce Ag Service, Inc. Dearborn, Mo. - Executive Summary

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DeBruce Ag Service, Inc in Dearborn, Missouri is an agricultural retailer of fertilizers and crop protection products to farmers in an 20 mile radius of Dearborn.  We maintain two anhydrous ammonia storage vessels that are currently not connected.  These storage vessels are 18,000 and 12,000 gallons each.  Our storage units each contain internal excess flow valves that provide positive shut-off of product flow in the event of a hose or  pipe failure. 
 
We have two possible alternatives of accidental product release beyond the failure of the storage tank itself.  The first would be the failure of either piping or transfer hose used to move product from the storage unit to nurse tanks (portable 1,000 gallon units).  A failure of this type would result in a small release of product (200#) prior to the excess flow valves detecting a large flow and snapping shut. The second possible release would result from the accidental release of product through pressure relief valves mounted on the stor 
age vessels to identify extremely high pressures, that open to discharge product to protect the storage unit from compelete tank failure.  These relief valves are designed to release product to a certain pressure and automatically reset themselves.  At DeBruce Ag we take active steps to avoid over pressurizing or overfiling storage vessels by maintaining a policy of never filling storage or transfer units beyond 85% of full capacity,  monitoring storage units for product expansion during extremely high temperatures, and reducing  tank volumes if neccessary.  We also inspect, maintain, and replace  the relief valves on both storage and nurse units at prescribed intervals.   
 
We have identified the worst case scenario to produce a release of 7,150# of anhydrous ammonia at a potential distance of 3.1 miles from the storage tank.  This worst case scenario would exist under adverse weather where there was low hanging clouds, high humidity, and minimal wind.  Anhydrous ammonia is a gas store 
d under pressure as a liquid, and releases to the atmosphere as a gas, unless injected in the ground by specialized application tools.  Any anhydrous ammonia released under the adverse weather conditions mentioned above would seek low lying areas, following creeks and drainage areas.  As a result, under the most adverse weather conditions the release would most likely move west and south from the storage plant area, following the terrain along Bee Creek, which runs on the west edge of our plant's property.  This would direct the greatest share of the release away from the more populase area of Dearborn, but would have the potential to reach the north side of the community of New Market via Bee Creek.  In the event of a release under these conditions the local LEPC (Dearborn Fire Department) and our business would need to take steps to notifiy the affected area of evacuation.  The North Platte High School complex sits .32 miles northeast of our storage tanks on a much higher elevation.  
In the event of a worst case scenario release, it is unlikely that an anhydrous ammonia cloud would reach to the height of the school's elevation.  However, appropriate steps would need to taken to prepare for an evcuation of the students.  A major release during ideal atmsopheric conditions (windy, dry) would most likely result in the quick dispersal of the gasses, but evacuation to the northeast of the plant would be likely due to the typical prevailing winds (from southwest) during these conditions. 
 
DeBruce Ag Service works in cooperation with the local LEPC to respond to any accidental releases of product from our storage vessels.  Internally, DeBruce Ag is pro-active in idenifying work hazards, and communicating those hazards to our employees, through regular safety meetings.  DeBruce Ag Service, Inc. believes that all level of employees are responsible for the health and safety of those employed by DeBruce Ag, as well as the community in which it operates.
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