City of Porterville Wastewater Treatment Facility - Executive Summary |
|
1. Acidental Release Prevention and Emergency Response Policies The City of Porterville- Wastewater Treatment Facility handles chlorine which is considered a hazardous material and is a regulated substance under the California Accidental Release Program (CalARP) and is considered in this Risk Management Plan (RMP). The properties of chlorine make it necessary to observe safety precautions in handling chlorine to prevent human exposure, and 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 of California rules and regulations. Safety depends upon the safe procedures used to handle chlorine; 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 Faciity is an eight (8) million gallon per day treatment plant for wastewater from domestic and industrial source s. The plant design has conventional primary treatment which screens coarse materials and removes grit and settleable organic soids. There is a conventional secondary treatment which removes soluable organic material and additional suspended organic solids. There is a solids handling system with dissolved floatation thickening of the waste activated sludge, anaerobic digestion of the primary and secondary organic sludges, and final disposal by land application. The influent entering aerated grit channels contains large numbers of biological organisms. Some of these may be pathogenic (disease causing) organisms. The Effluent is disinfected to protect the public health by the use of a chlorine solution produced at the plant by mixing chlorine gas and water. Additional chlorine is added at the secondary clarifiers. Further chlorine gas is added at the chlorine contact tank to provide detention time for the chlorine to disinfect the treated wastewater. There is a daily maximum of 20,000 pounds of chlorine at the facility. 3a Worst Case Release Scenario The Worst Case release scenario for inerconnected equipment must consider the largest quantity of a regulated substance handled on site in a single vessel at any time, taking into account administrative controls on the vessel's contents and usage as per the CCR Title 19 Division 2 Chapter4.5 Article 2 Section 2750.3 (b). The one ton container of chlorine is the largest vessel in the chlorine feed system. The one ton container is, at most, filled with 2,000 pounds of liquid chlorine which is 67% of tank capacity. the Worst Case release scenario for the one ton container of chlorine is the release of the 2,000 pounds of chlorine at the rate of 200 lb/min for 10 minutes. The distance to the endpoint of 3 ppm for Worst Case scenario is 3.1 miles. This release will extend beyond the boundaries of the stationary source. 3b. Alternative Release Scenario The Alternative Release scenario for the one ton con tainer of chlorine is complete failure and separation of a 1/4" diameter fuse plug insert. The loss from the one ton container will continue until the liquid contents left in the one ton container solidify due to withdrawl of the Heat of Vaporization by the escaping chlorine vapor. This amounts to a loss of 252 pounds of liquid chlorine from the one ton container in one (1) hour which flashes to vapor. The chlorine vapor is drawn from the Chlorine Building to a treatment system with a scrubber. The treated fumes from the Chlorine Building exit the exhaust stack of the scrubber with, at most, 5 ppm chlorine concentration. The distance to the endpoint of 3 ppm for the Alternative Release scenario for the chlorine bulk tank is 39 feet. this release will not extend beyond the boundaries of the stationary source. 3c. Administrative Controls Administrative control to limit the distances for each reported scenario exists to restrict to a minimum, the amount of chlorine lost from a on e ton container if an accidental release were to occur; and preferably to not have a release occur. This administrative control is inherent in the operational procedures for the chlorine process system and the training provided to the operators of the chlorine process system. 3d. Mitigation Measures Mitigation measures to limit the distances for each reported scenario exist to restrict the amount of chlorine released to a minimum, if a release were to occur; and preferably to not have a release occur. the mitigation measures are based upon th edesign, inspection, testing, and maintenance of the chlorine process systems; their related equipment and components; and the treatment system. 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 th e chlorine process system and the related activities and equipment represents the facility's main active commitments to an accidental release prevention program. 5. Five Year Accident History In 1998 a relase of approximately 140 pounds of gases chlorine occured but was contained within the chlorine building with no gas escaping into the atmosphere. The City of Porterville strongly believes that the release of chlorine was far less than reported but because the only way of determining the weight of the cylinder was the scales at the facility this reading was reported. The scales on the cylinders were inaccurate and shortly after they were sent back to the manufacturer for recalibration. 6. Emergency Response Program The Emergency response program is based upon alerting personnel at the facility to evacuate the facility and await the arrival of responders from the City of Porterville Fire Department at the evacuation assembly location if a release occurs that causes the evacuati on to be initiated. The Tulare County- Environmental Health incorporates this response into the County AreaPlan for the Regional Local Emergency Planning Committee. 7. Planned Changes To Improve Safety There are commitments made under the Process Hazard Analysis element of the Process Safety Management (PSM) that are planned to be implemented over the next year. Current applicable codes and regulations are reviewed as part of the PSM to determine if other commitments need to be made to achieve increased operational safety for the regulated chlorine process system. These commitments will be prevention and mitigation measures for accidental releases of the regulated substance. |