Harris Field Water Treatment Plant - Executive Summary |
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INTRODUCTION At the turn of this century water borne diseases were a leading cause of death in the United States. Epidemics of typhoid, cholera, dysentery and other water-borne diseases occurred. After chlorine's introduction into public water supplies, deaths from typhoid in the U.S. dropped dramatically from 25,000 in 1900 to less than 20 in 1960. Water-borne disease is even still a leading cause of infant mortality in many countries throughout Asia, Africa, and Latin America where infant mortality rates are 10 to 20 times greater than in the U.S. In the U.S., however, water-borne disease has been virtually eliminated due to an effective public health strategy of utilizing chlorine for drinking water disinfection. Chlorine disinfection is arguably one of the greatest achievements for public health worldwide in the last hundred years and is credited with increasing the life expectancy of Americans by more than 50 percent. The use of chlorine is not risk free, however. Historica lly it is clear that utilities have recognized the risks and have been successful in developing procedures to handle chlorine safely and to protect the off-site public and the environment from potential accidental releases. As an added layer of protection, the United States Environmental Protection Agency promulgated Hazardous Chemical Risk Management Program regulations to further ensure that facility owners understand the risks and take proactive efforts to reduce risk through comprehensive training programs, procedures, and risk mitigation measures. Additionally, EPA wanted the public to be informed regarding these issues. City of Homestead Water and Wastewater Department has always understood these risks and has maintained a well-trained staff and a safely operated and maintained facility. The City of Homestead track record is exemplary with respect to handling hazardous chemicals. Furthermore, the City of Homestead has taken a comprehensive approach to be in full compliance w ith the RMP regulation by June 21, 1999 and a proactive approach to a public information program which is above and beyond the requirements of the regulation. FACILITY BACKGROUND The City of Homestead owns and operates the Harris Field Water Treatment Plant. The facility's mission is to protect public health by providing our community with safe drinking water, free of harmful pathogens. Approximately 95 pounds per day of chlorine gas is used to disinfect the water and make it safe for human consumption. A maximum of 16,000 pounds of chlorine are stored on-site. The chlorine is stored as a gas that is liquefied under pressure in containers that contain 2,000 pounds each. CHLORINE PROCESS AND SAFETY EQUIPMENT Harris Field Water Treatment Plant injects chlorine to the water system by use of vacuum feed through vacuum regulators. This system will automatically shut-off at loss of vacuum to prevent unwanted escape of gases into the atmosphere. The chlorine storage tank are locate d away from possible traffic and are enclosed by poured concrete structure building with fencing surrounding. RISK MANAGEMENT AND PROCESS SAFETY MANAGEMENT PROGRAM OVERVIEW Chlorine is subject to the Environmental Protection Agency's (EPA's) Risk Management Program (RMP) regulation which can be found in 40 CFR 68 and the Occupational Safety and Health Administration's (OSHA's) Process Safety Management Program (PSMP) regulation which can be found in 29 CFR 1910.119. The primary components of the RMP are as follows: * A five-year accident history * An off-site consequence analysis for a worst-case and alternative release scenario * A comprehensive prevention program to minimize risks (i.e. minimize the potential for a release) * An emergency response program to ensure that an accidental release is appropriately handled * An overall management program to supervise the implementation of the RMP Followi ng development of the RMP, the facility must submit a Risk Management Plan (Plan) to the EPA by June 21, 1999. The Plan is a summary of the facility's Risk Management Program. The RMP will be updated every five years, or whenever a process changes or a new process is added. The OSHA PSM regulation has basically the same requirements as the prevention program element of the EPA RMP. The Harris Field Water Treatment Plant RMP meets the requirements of both regulations. The following sections briefly summarize the elements of the Harris Field Water Treatment Plant RMP. FIVE-YEAR ACCIDENT HISTORY The Harris Field Water Treatment Plant has used chlorine to disinfect water for 15 years. In the last five years, the facility has had no accidental releases, which were required to be reported under the RMP regulation. It is important to note that the facility has never had an accident that resulted in the worst case nor the alternative release scenarios outlined herein. WORST-CASE RELEA SE SCENARIO The worst case release scenario for a toxic gas has been defined by the EPA to be an accidental release in which the largest on-site vessel containing chlorine releases its contents as a gas over ten minutes. Since the largest container stored at the facility holds 2,000 pounds of chlorine, the worst case release scenario is a release of 2,000 pounds of chlorine over 10 minutes. This scenario was modeled using RMP*Comp software to estimate the distance to an endpoint of 3 ppm. It should be noted that this concentration has been found to typically cause minor eye and nose irritation. ALTERNATIVE RELEASE SCENARIO The alternative release is a "more likely" incident than the worst-case. The RMP regulation allows the owner to define the alternative release scenario based on historical experience or operations staff knowledge of their system. The alternative release scenario for the facility was assumed to be a tank rupture. This scenario was modeled using RMP*Comp softwa re to estimate the distance to an endpoint of 3 ppm. It should be noted that this concentration has been found to typically cause minor eye and nose irritation. PREVENTION PROGRAM There are always inherent risks associated with handling and using chlorine. These risks include the potential inhalation of chlorine gas if it is accidentally released. The prevention program is a key component to reducing the risk associated with a potential chlorine gas release. Key elements of the prevention program include: * Employee participation * Process safety information * Process hazard analysis * Incident investigation * Standard operating procedures * Mechanical integrity * Management of change * Pre-startup review * Training * Contractors * Compliance audits * Hot work permits * Trade secrets The following briefly states the benefits of the following prevention program elements: standard operating procedures, mechanical integrity prog ram, employee training and the process hazard analysis. The facility staff has developed up-to-date and accurate written standard operating procedures (SOPs) to ensure that operators have clear instructions for safe operation of the chlorine system. Effective SOPs, when combined with operator training, are instrumental in ensuring safe operation of the system and in preventing accidental releases. The purpose of the mechanical integrity program is to ensure the continued integrity of the process equipment. An effective mechanical integrity program is integral to preventing accidental chlorine releases that may result from mechanical failure of improperly maintained equipment. The Harris Field Water Treatment Plant mechanical integrity program includes maintenance, inspection, and testing procedures and schedules along with maintenance personnel training. Knowledgeable well-trained personnel are essential to preventing and mitigating the effects of accidental chemical releases. T he Wittkop Water Treatment Plant training program ensures that personnel working on or near the chlorine system are adequately trained in operation and maintenance procedures and the appropriate response actions to an accidental chlorine release. The process hazard analysis is a valuable risk reduction tool that outlines deficiencies in equipment and procedures, identifies potential system failure modes, and provides recommendations for system and operational improvements. EMERGENCY RESPONSE PROGRAM A comprehensive emergency response program has been prepared which outlines the procedures and lines of communication that are necessary to effectively respond to and mitigate a potential chlorine gas release. Harris Field Water Treatment Plant is equipped with automatic vacuum shut-off regulators which prevent accidental release of gases if vacuum is loss. The facility emergency response program includes procedures for notifying the local hazardous materials (hazmat) teams of the incide nt and procedures for evacuating the facility. There are local hazmat teams in Miami-Dade County that can respond to mitigate a chlorine leak. Facility staff have coordinated with the local hazmat team and/or fire department to ensure that they are fully trained and equipped to quickly respond to an incident. |