Murphree Water Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY Gainesville Regional Utilities (GRU) owns and operates the Murphree Water Treatment Plant, located at the intersection of Northeast 15th Street and Northeast 53rd Avenue in Gainesville, Florida. Since 1975, Gainesville's drinking water demand has been supplied by the Murphree plant. Originally built as a state-of-the-art water plant, it remains as one of Florida's most efficient and modern water treatment facilities. Like the majority of municipal water treatment plants in the United States, gaseous chlorine is used at the Murphree plant as a disinfectant to destroy pathogenic organisms that could enter the filtered water distributed by pipe to customers. The popularity of chlorine as a water disinfectant is mainly due to its effectiveness, relatively low cost, and ability to produce a measurable residual in the finished water. At the Murphree plant, chlorine is also used to control odors from the naturally-occurring sulfurous gas contained in the raw water supp ly. The same properties that make chlorine valuable as a disinfectant also make it necessary to observe certain safety precautions in handling chlorine as a safeguard to our workers, our community, and the environment. Chlorine is notably irritating to the eyes, nose, throat and lungs. More serious human health effects could result from much higher chlorine exposure, such as intense coughing, chest pains, and in extreme cases, death. GRU's commitment at the Murphree is to store, handle and use chlorine in a manner that achieves the needed benefits of disinfection while minimizing both onsite and offsite risks. This is accomplished by designing a safe process, maintaining the process in optimum working condition, operating safely through documented procedures and extensive training, and providing an emergency response capability to minimize the consequences of a chlorine release, should a process accident ever occur. Our commitment to employee and community protection is demonstra ted in the fact that over Murphree's 24-year history, there have been no chlorine accidents that resulted in death, serious employee injury or offsite consequences. Accidental Release Prevention and Emergency Response Policies It is GRU's policy to adhere to all applicable Federal, State of Florida and local rules and regulations. This specifically includes compliance with the Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA) rules for chlorine accidental release prevention and emergency response. The primary measures for accidental chlorine release prevention are contained in the document Process Safety Management/Risk Management Program for Murphree Treatment Plant. This process safety management (PSM) document was prepared in conformance with the OSHA and EPA risk management rules, as well as industry-specific guidelines and best management practices relevant to release prevention. Murphree's Plant Manager has the responsibility for ensuring that this program is implemented in the workplace as written. GRU's emergency response program is based upon the Chlorine Institute's Pamphlet 64, Emergency Response Plans for Chlorine Facilities. The Murphree emergency response plan relies on a team of onsite trained personnel and, as necessary, offsite mutual-aid groups such as fire and rescue services. The emergency response plans at Murphree are based on the Incident Command system, where onsite responders work in coordination with local hazardous materials response teams to implement the Murphree and regional response plans. Murphree's personnel receive annual chlorine emergency response training, which includes the donning of protective equipment and hands-on application of the chlorine cylinder repair kits kept at the plant. As the plant operates 24 hours-per-day, 7 days-per-week, so also is an onsite emergency response team always present to respond immediately to a release. Stationary Source and Regulated Su bstances Handled Chlorine is received by the facility by truck and is stored in one-ton chlorine cylinders fabricated to Department of Transportation (DOT) specifications. Upon arrival at the site, all chlorine cylinders are thoroughly inspected and if there is any doubt about the integrity of the cylinder, it is promptly refused. Once accepted, the cylinders are stored inside an enclosed building equipped with a chlorine detector that immediately notifies the operators of a release should a leak occur. Four cylinders are connected to the disinfection process: two are in-use, and two are as standby. The standby cylinders will automatically switchover when the in-use cylinders become empty, ensuring continuous disinfection. The maximum intended chlorine inventory at Murphree is 18 cylinders, or 36,000 pounds of chlorine stored in the building. The Worst-Case and Alternative Chlorine Release Scenarios As part of Murphree's emergency prevention and response efforts, a hazard asses sment was conducted in compliance with EPA requirements contained in 40 CFR 68, Subpart B. The hazard assessment included the development of worst-case and alternative release scenarios. EPA defines a worst-case release as a scenario involving the greatest amount held in a single vessel or pipe. In Murphree's case, this involves the release of the entire contents of a one-ton chlorine cylinder. The release is assumed to occur over a 10-minute period, and only the passive mitigating effects of the building enclosure may be considered. Applying the worst-case parameters to the Murphree situation results in a distance to chlorine endpoint (defined as 0.0087 milligrams per liter) of 0.9 mile. In other words, any human or environmental receptors within 0.9 mile of the chlorine storage building are within the worst-case distance. EPA defines an alternative release as a scenario more likely than the worst-case, but that nevertheless results in an impact offsite (unless no such release is possible). Passive and active mitigation measures (chlorine detection, operator response, etc.) are considered in this scenario. Without an accident history on which to base a more likely scenario, a scenario was selected based on information provided in the Chlorine Institute Pamphlet 74, Estimating the Area Affected by a Chlorine Release. The scenario involved the release of chlorine gas from a faulty fuse plug leak on the cylinder inside the building. Response time is conservatively assumed to occur in 30 minutes. This scenario results in a distance to chlorine endpoint of less than 0.1 mile. There are no public or environmental receptors affected by this release. The distance to endpoint calculations were performed using EPA's RMP*Comp model. The RMP*Comp model was developed specifically for compliance with the accidental release prevention requirement for predicting the travel distance of an accidental release. General Accidental Release Prevention Program and Specific Prevention Steps GRU's PSM document contains 13 essential release prevention elements. Some of the key accidental release prevention elements of the PSM program are as follows: * Process hazard analysis: This analysis was performed for each step in the chlorine process, to identify potential process failure scenarios and the appropriate prevention or response measures. The process hazard analysis will be updated every 5 years. * Operating procedures review: The review was conducted to ensure that operators are given clear, written instructions for safely operating the chlorine process. * Training programs: Training is given to each employee assigned to the process with continuing operator training thereafter, with an emphasis on safe chlorine handling and emergency response. GRU has been on the forefront among utilities in chlorine safety training. GRU's Utility Training Officer, for example, helped in the preparation of the training manual entitled Chlorine Handling , Containment and Emergency Response. * Contractors: GRU ensures through its contract provisions that contractors supplying or working with chlorine are held to a standard of safety performance that complies with GRU's safety goals and objectives, and also meets relevant agency requirements. For example, GRU personnel make unannounced visits to the supplier's site to ensure that rules and guidelines concerning chlorine and cylinder integrity are being followed. * Mechanical integrity: The integrity and reliability of the process is maintained by implementing preventive maintenance and routine inspection and testing procedures. * Management of Change: The management of change procedures provide a systematic approach to evaluate and control the safety and health aspects of any significant change to the process chemicals, technology, equipment and operating procedures. * Incident Investigation: GRU investigates within 48 hours any accidents or "near misses" that could have resulted in a chlorine release, in order to develop measures to prevent a recurrence. The above elements are only part of GRU's aggressive safety program. In addition to the 13 PSM elements, GRU has established related OSHA safety programs such as hot work and confined space. These OSHA safety programs apply to both GRU and contractor employees. Five-year Accident History There have been no accidents involving chlorine at the Murphree plant in the past five years. Emergency Response Program Murphree plant operators are provided with annual chlorine safety training that includes hands-on practice of assessing and repairing a chlorine leak with a leaking cylinder simulator. Plant personnel also review the emergency response flow diagram and emergency plan on an annual basis. The emergency response plan covers all aspects of emergency response including escape procedures and routes, procedures for post-evacuation employee accounting, notification procedures, rescue and medical duties, and response procedures for spills or leaks. If a major chlorine leak were to occur, the emergency plan requires immediate notification of the regional hazardous materials response teams for assistance, including orderly evacuation or sheltering-in-place of the surrounding community. Planned Changes to Improve Safety GRU is committed to exploring ways to further reduce or eliminate the possibility of a release from its disinfection process. Toward this end, an alternative disinfection study is being conducted to evaluate the effectiveness and feasibility of using an alternative chemical disinfectant to replace chlorine. GRU is committed to continuously improving the safety of its operations for the benefit of its personnel, the citizens of Gainesville and the environment. |