Wastewater Treatment Plant - Executive Summary |
|
Mammoth Community Water District Accidental Release Prevention and Emergency Response Policies: The Mammoth Community Water District provides wastewater service to the Town of Mammoth Lakes, California. The Service area is located at an elevation of approximately 8,000 feet on the eastern side of the Sierra Nevada mountain range. The town is surrounded by the United States Forest Service lands and is heavily utilized as a recreational area. . The District has instituted a Risk Management Program to ensure that its facilities utiizing regulated hazardous chemical substances are operated according to the rules established by the United States Environmental Protection Agency Through its risk managment program, the District has performed a hazard assessment to assess the potential effects of an accidental release of a hazardous substance. This assessment includes performing an off-site consequence analysis including analysis of a worst-case scenario and one alternative release scenario. The District has established a prevention program to prevent accidental releases of regulated hazardous substances. This program includes safety precautions and maintenance, monitoring and employee safety training A response program has also been established that requires specific action to be taken in emergency situations. This includes procedures for notifying public and local agencies responsible for responding to accidental releases, information on emergency health care, and employee response training measures. Description of Facilities and Regulated Substances Handled The District's wastewater treatment facility utilizes chlorine g as for disinfection purposes. This facility is located at the eastern edge of the town and treats all wastewater generated by the community. The facility is considered a secondary treatment facility and includes processes of primary clarification, biological treatment, secondary clarification, filtration and disinfection. Chlorine gas is injected into the treated wastewater to kill any potential disease causing organisms. Up to eight cylinders containing 2,000 pounds of chlorine gas each are stored at this facility. Worst Case Scenario A worst-case release scenario at the wastewater treatment facility would involve major damage to a valve incurred while loading or offloading chlorine gas cylinders. This could result in a release of chlorine gas from the container at a rate of 200 lbs. per minute with the release lasting ten minutes. At this release rate, toxic gas could extend over a distance of 1.3 miles. The affected area would involve a maximum of 13,21 0 people and would include residential areas, industrial area, commercial area, hospital, and elementary, middle, high school and college level students. Alternative Release Scenario The alternative release scenario at the wastewater treatment facility is similar to that considered for the water treatment facility. A leak would occur at the valve while the cylinder was being connected into the system. At a release rate of one pound per minute, toxic gas would extend over a distance of 0.1 miles. A toxic atmosphere could impact the District operations and administrative offices and could involve 32 people. Again, it is unlikely that the entire content of a cylinder would be released because personnel would be on hand to immediately respond and stop any leakage. Additional Scenario Concerns to the Community In addressing the earthquake disaster potential, the one ton containers are cradled on engineered blocks attached to the floor and strapped in place which prevents movement. The connecting lines from the cylinders to the system are made of flexible material. This has proved a very effective method during high earthquake activity. The most recent series included an earthquake with a magnitude of 5.6 on the richter scale with no incident at the plant. General Accidental Release Prevention Program and Chemical-Specific Prevention Steps The District is currently in compliance with the Occupational Safety and Health Administration rule for Process Safety Management and with the Risk Management Plant rule. Specific prevention steps that the District has taken include a computerized alarm system that immediately notifies emergency personnel of potential chemical release situations. Minimal amounts of chlorine gas in the atmosphere will trigger on-site alarms and provide notification. District personnel also receive specific training in the handling of chlorine cylinders and apparatus and in emergency repai r. Only the necessary amount of chlorine required for use in the treatment processes is stored at the wastewater facilities to minimize the potential hazards. Five-Year Accident History The District has experienced no accidental release of chlorine gas during the last five years and , in fact, has not experienced any accidental releases since it began using chlorine in 1972. Emergency Response Program The District has developed and trained an emergency response team that is qualified to respond to and make repairs necessary to stop an accidental release of chlorine gas. Other District employees have also been trained in the first responder, awareness level and first responder, operations level response to accidental releases of chlorine. The District has also coordinated with the Mammoth Lakes Fire Department and Mammoth Lakes Police Department in responding to an accidental release of chlorine. As stated above, District facilities that u tilize chlorine gas are equipped with alarm instrumentation that will immediately sense minimal levels of chlorine in the atmosphere. These alarms are connected to a District computer that will immediately notify emergency personnel of a potential chemical release condition. At this stage the District's emergency response plan is placed into action. Planned Changes to Improve Safety The District plans to focus on training in the future to refine its response capabilities. Full scale emergency response to actual scenarios will be practiced on a quarterly basis. Monthly meetings are scheduled for the emergency response team to review the needs and objectives of the team. Annual re-certification will be provided as required by OSHA. New training equipment will be purchased during the upcoming year. |