City Of Reedley Wastewater Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY 1. Accidental Release Prevention and Emergency Response Policies This facility handles chlorine and sulfur dioxide which are considered hazardous materials. The properties of chlorine and sulfur dioxide make it necessary to observe safety precautions in handling these chemicals to prevent human exposure, and to reduce the threat to the facility's workers and nearby members of the community. It is the facility's policy to adhere to all applicable Federal and State rules and regulations. Safety depends upon the safe procedures used to handle chlorine and sulfur dioxide; the safety devices and systems designed and constructed into the facility; and the training of the pertinent personnel. 2. Stationary Source and Regulated Substances Handled The City of Reedley operates a 2.77 million gallon per day (MGD) wastewater treatment plant and disposal facility. Disposal is to 23 acres of percolation-evaporation basins with an underdrain system. Treated effluent is also av ailable for farm irrigation. During a three to four month period during the winter, when the evaporation rate is not sufficient to supplement the percolation capacity of the ponds, and when the Kings River is flowing at a rate to provide an adequate dilution rate, excess, treated, percolated, disinfected and dechlorinated effluent can be diverted to the Kings River. At these times, chlorine gas is injected into water to form a concentrated chlorine solution. This solution is then mixed with water received from the percolation pond subdrains for disinfection and then dechlorination prior to discharge into the Kings River. The dechlorination is accomplished by sulfur dioxide gas injected into water to form a concentrated sulfur dioxide solution which is mixed with the disinfected water. The chlorine and sulfur dioxide are each received in one ton containers. Gaseous chlorine is obtained from a one ton container connected by a vacuum regulator to a chlorinator which feeds the chlo rine gas under vacuum to an injector where the chlorine gas is injected into a water flow. Gaseous sulfur dioxide is obtained from a one ton container connected by a vacuum regulator to a sulfonator which feeds the sulfur dioxide gas under vacuum to an injector where the sulfur dioxide gas is injected into a water flow. 3a. Worst Case Release Scenario The largest storage vessel is a one ton container of chlorine for the chlorine system and a one ton container of sulfur dioxide for the sulfur dioxide system. Failure of either container will release 2,000 lb of chlorine or sulfur dioxide. It is assumed that the entire 2,000 lb is released as gas in ten minutes. The assumption is made that the gas release from the one ton container is directly to the surrounding atmosphere. The distance to the endpoint of 3 ppm for the Worst Case scenario for either the chlorine or the sulfur dioxide will extend beyond the boundaries of the stationary source. The chlorine release is reported as the Worst Case scenario since the end-point distances are identical for the chlorine or sulfur dioxide releases. 3b. Alternative Release Scenario The Alternative Release scenario is considered as a small leak in the packing material around the valve stem of the vapor phase valve located on the one ton container of chlorine and the one ton container of sulfur dioxide. There are no active or passive mitigation measures that would reduce the amount of chlorine or sulfur dioxide released or treatment system to which the released chlorine or sulfur dioxide would be directed. It is assumed that there is a release of 0.5 lb/min which would continue for a period of sixty minutes. During that time, a total of 30.0 pounds of chlorine or sulfur dioxide would be released. The distance to the endpoint of 3 ppm for the Alternative Release scenario for the chlorine or the sulfur dioxide will extend beyond the boundaries of the stationary source. 3c. Administrative Controls Administrative control to limit the distances for each reported scenario exists to restrict the amount of chlorine or sulfur dioxide released to a minimum, if a release were to occur; and preferably to not have a release occur. This administrative control is inherent in the operational procedures for the chlorine and sulfur dioxide systems and the training provided to the chlorine and sulfur dioxide system operators. 3d. Mitigation Measures Mitigation measures to limit the distances for each reported scenario exists to restrict the amount of chlorine or sulfur dioxide released to a minimum, if a release were to occur; and preferably to not have a release occur. The mitigation measures are based upon the design, inspection, testing, and maintenance of the chlorine and sulfur dioxide systems and their related equipment and components. 4. General Accidental Release Prevention Program and Chemical Specific Prevention Steps The facility complies with all applicable federal and state codes and regulations. There are safety meetings and safety training. The Process Safety Management (PSM) program implemented at the facility for the chlorine and sulfur dioxide related activities and equipment represents one of the facility's main active commitments to an accidental release prevention program. 5. Five Year Accident History There have been no accidental releases of chlorine or sulfur dioxide within the last five years. 6. Emergency Response Program The Emergency Response Program is based upon the alerting of personnel at the facility to evacuate the facility and await the arrival of responders from outside the facility at the evacuation assembly location if a release occurs that causes the evacuation to be initiated. This response can be incorporated into the Area Plan for the Local Emergency Planning Committee. 7. Planned Changes To Improve Safety Any commitments made for scheduled mitigation actions are listed in the element (e) (i.e. Process Hazard Analysis) of the Process Safety Manage ment (PSM) document. These mitigation actions are being implemented at this time for the next year. Current applicable codes and regulations are being reviewed to determine if other commitments need to be made to achieve increased operational safety for the chlorine and sulfur dioxide systems. |