Shelbyville Waste Water Treatment Plant - Executive Summary |
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The Shelbyville Watewater Treatment Plant accidential release prevention policy includes procedures, management practices and newly purchased technologies. All U.S.E.P.A. Prevention Program procedures are followed. The Shelbyville Watewater Plant has an emergency response policy and utilizes emergency response services both inside and outside of the community, which complies with E.P.A. Emergency Response Program requirements. The Shelbyville Wastewater Plant feeds chlorine to the plants effluent for disinfecting purposes. The plant is located at 525 West Jackson Street next to the Duck River at mile 221.3. The chlorine room has only chlorine equipment which includes chlorinators, liquid chlorine cylinders and chain hoist. New state of the art chlorine gas detectors coupled with automatic cylinder shutoff system will be installed in July 1999 or sooner. Also being installed are trouble lights and audible horns both at the cholorine room and also lab area of main contorol buildin g. The maximum amount of chlorine on hand would be four one-ton cylinders. The chlorine room is located adjacent to the main control building. The chlorine room is checked several times each day by operators and maintenance personnel. Under the E.P.A. Offsite Consequence Analysis Guidance for Chlorine considerations of two chlorine release scenarios identified as "Worst Case Scenario" and "Alternative Release Scenario". The worst case scenario is defined by E.P.A. and states that the owner or operator shall assume that the maximum quantity in the largest vessel is released as a gas over 10 minutes, due to unspecified failure. The alternative scenario is defined as a more likely to occur than the worst case scenario. At worst case scenario using 10 minute release, F stability atmospheric conditions, wind speed of 1.5 meters per second and a 2,000 pound vessel, the distance to end point in a urban area is 1.3 miles. In this 1.3 mile radius there are approximately 5,800 people. H owever, only a portion of the total number of people would be affected since the gas cloud would travel in an elliptical plume extending downwind from the release point. Although, not used in our "Worst Case Scenario", mitigation factors exist. Passive mitigation would be the enclosed chlorine room itself. Active mitigation will be the chlorine gas detector and automatic cylinder shutoff when installed. This should further reduce the plume area and allow more time for emergency response to the area. The "Alternate Release Scenario" for chlorine release using E.P.A. Off-Site Consequence Analysis Guidance is a 60 minute release, D stability atmosheric conditions and wind speed of 3.0 meters per second. The distance to the end point would be 0.06 miles or 317 feet. In this 0.06 mile radius approximately 50 people could be affected. This scenario could be caused by a rupture of the flexible connecting line (pigtail). If this scenario actually came to pass, an active mitigation wou ld be the chlorine gas detector sending a signal to the automatic cylinder shut-off system that will turn the cylinder off at the cylinder valve, thus preventing continuos leakage. This coupled with a passive mitigation of being in an enclosed room would help reduce chlorine gas escaping into the atmosphere. In actuality, the passive mitigation of an enclosed room should help significantly in control of a chlorine gas leak in both scenarios helping in response time which also will help protect the citizens, the environment and employees at and around the Wastewater Plant. A rupture in the flexible pigtail was selected for the alternative scenario because this seemed to be the worst of the most probable accident that we may have in our chlorine room. With this in mind, we think with the training of our employees, the safety devices being installed and the design of the room itself, this most likely release would be quickly, efficiently and safely controlled to protect humans and the environment. With this ability and our on going programs we are in compliance with the OSHA PSM rule. Steps taken by this company in managerial, operator and maintenance training along with technological systems, emergency response services available in the community help ensure safe use and handling of chlorine in our process. For the five year accident history at the Shelbyville Wastewater Plant there has been no accidental releases or personal injuries in our chlorine process. The Shelbyville Wastewater Plant has an Emergency Action Plan as required by OSHA. This plan coordinates with our emergency Management Director, Local Fire Department and Police Department. It also includes our contracted Emergency Response Team. The employees have training in safe handling and use of chlorine. The employees are included under 40 CFR Part 68.83, Employee Participation, so they can voice their ideas and fill out questionnaires for making suggestions. All training and employee particip ation will be documented and kept on file. Employee training on Self-Contained Breathing Apparatus is also kept of file. There are planned changes to continue to improve safety here at the Shelbyville Wastewater Plant. More in depth training to all operators and maintenance personnel. There will be an increase in employee participation on ideas and suggestions to improve safety and hazard awareness. The purchase of new state of the art chlorine gas detectors along with chlorine cylinder shuoff systems will be installed by the end of July 1999 or sooner. Other mitigation systems have been discussed and chosen and will be implemented in the near future. There has been recommendations identified. These recommended actions have been evaluated and will be implemented as required. |