K. R. Harrington Water Treatment Plant - Executive Summary

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1.     The city of Nashville's Department of Water and Sewerage Services (Metro Water Services) Risk Management Plan is a combination of technology, procedures, training, and management.  Each element of the US Environmental Protection Agency Risk Management program is addressed.  The approach is to prepare a plan tailored for each facility to increase knowledge, prevent accidents, and to respond to emergencies. 
2.  The K. R. Harrington Water Treatment Plant has been in existence in its current location for 22 years.  The Plant is currently rated to treat a maximum capacity of 90 million gallons of water each day.  The facility is located East of downtown Nashville and is situated on approximately 43 acres.  Along with the Omohundro WTP, K. R. Harrington WTP produces potable drinking water for the service area.  The Plant utilizes the conventional treatment process to produce potable drinking water.  
Chlorine is utilized in this process train to disinfect the water.  The chlorine feed system includes piping, valves, pressure gauges, evaporators, and chlorinators.  Chlorine is hazardous because it is a respiratory irritant when inhaled.  Liquid chlorine is stored in a minimum of eight one-ton cylinders.  The cylinders are located inside a dedicated storage room. The amount of chemical used averages around one half ton per day depending on raw water conditions and flow.  The chlorine cylinders are monitored continuously by chlorine detectors with audible alarm systems.  Plant operators also inspect the cylinders hourly. 
3. Off site consequence analysis has been completed for chlorine gas.  Both the worst case and the alternative scenarios have been calculated using three different methods.  Manual calculations, TVA air models, and RMP Comp were all used and each method achieved virtually the same results.  The calculations used here are from TVA.  In the worst-case scenario (cylin 
der destruction), approximately 2000 pounds of liquefied chlorine released at 138 psi would have an estimated end point of 5.4 miles.  The total population affected in this scenario would be 168,475. 
4.     In the alternative scenario, a leak on a 0.25-inch line on a ton cylinder is leaking 6.43 pounds per minute for 5 minutes.  The endpoint would be 0.12 miles. 
5.    The accident release prevention program for K. R. Harrington Water Treatment Plant includes extensive operator training, a Preventative Maintenance program for chlorine equipment, state of the art process and safety equipment, written operating procedures, scheduled performance reviews for procedures and equipment, and implementation of a compliance inspection program. 
6.  No off site accidental releases have occurred at this plant in the previous five years. 
7.    The plant has an emergency response plan and the Nashville Fire Department is aware of the possible hazards.  Metro Water Services and the Nashville Fire  
Department are members of the Local Emergency Response Planning Committee (LEPC).  The program includes a response decision flow chart and a notification plan.  Plant personnel respond to and repair minor leaks and the Fire Department are called in the event of a significant accident. 
8.    Future plans include a more extensive training program for the plant staff.  Training is now scheduled to begin September, 1999. New safety equipment planned will include additional chlorine alarms and an automatic shut off system for the one ton chlorine cylinders.
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