Worthington Municipal Wastewater Treatment Plant - Executive Summary |
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Programs for chlorine release prevention and emergency response policies are reviewed and up dated by the MMUA (Minnesota Municipal Utilities Association) annualy. Chlorine is the most hazardous substance that we handle and any release will be called in to the Nobles County Emergency Management Office for public safety. The Wastewater Plant is a facility that uses chlorine for the disinfection of wastewater just before the water enters the receiving stream. The chlorine is contained in metal cylinders which hold 2,000lbs of chlorine, the maximum number of ton cylinders on site will be three during the required disinfection months of April--Oct. The cylinders are housed in a separate building at the southeast corner of the plant. The months of Nov--March no disinfection of the water is required and the plant will have below the threshold limit of chlorine (2,500lbs) on site. A worst case scenario would involve a one ton cylinder being dropped during handling and rupt uring causing the entire contents to spill onto the ground which would immediatly start vaporizing. The chlorine gas would form a cloud that would stay low to the ground and move with the wind. If the wind was from the north-east the cloud would travel across the surface of the ground to a safe endpoint three miles away. The town is a mile from the plant in a southerly direction, this spill would necessitate the evacuation of nearly 10,000 people. A call to the County's Emergency Operations Coordinator would set the Emergency Response Program into effect. An alternative release scenario would involve chlorine gas coming from a half inch hole in a section of feeder tubing in the building. The chlorine gas being released would set off the chlorine gas monitor in the building which would alert the crew. All the employees are trained in the use of PPE (personal protective equipment) which would be used in this scenario. At a minimum, three members of the staff would work on th e problem with two of the three being equipped with NIOSH approved self contained breathing apparatus and they will evaluate the situation and correct it if possible, the other man will be on the outside ready to call for extra help if needed. In this scenario the wrench on the chlorine tank feed valve will be used to close the valve which will stop the flow of gas through the damaged feeder line. The scenario described would be termed an incidental response and could be handled at the plant. The toxic end-point would be reached under this scenario about 0.3 of a mile from the building and would involve no offsite impact. General accidental release prevention at the site include a warning system with a chlorine gas detector which is mounted on an adjacent wall according to specifications, in the chlorine building, and will activate an audible alarm at the site if chlorine gas is detected. A written policy on chlorine building entry as well as chlorine handling procedures are either posted at the building site or at the main control building. All connections and piping are checked on a regular basis. Training is required of all employees on the handling of chlorine and the safety programs involved with chlorine. There has been no accidental releases of chlorine at the wastewater plant up to the present time. The emergency response program involves coordination with the Nobles County Emergency Operation Plan during a chlorine release. The Nobles County Emergency Management Coordinator would direct required responses of the various units of government involved. The wastewater personnel are trained and equipped to handle only incidental responses, gasket failure, valve leakage etc. The plant has an emergency response plan on site for step by step procedures that must be taken depending on the severity ( level 1,2,or3) of the release. The improvement of the safety programs at the plant will be continually reviewed and any new control equi pment will be looked at and evaluated. Training will be an ongoing program involving personal protective equipment(PPE), classroom training and policy reviews. |