South Water Reclamation Facility - Executive Summary |
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Orange County Utilities (OCU) owns and operates the South Water Reclamation Facility (WRF), located at 4760 Sandlake Road in Orlando, Florida. Like the majority of municipal wastewater treatment plants in the United States, gaseous chlorine is used at the South WRF as a disinfectant to destroy pathogenic organisms in the treated water. The popularity of chlorine as a wastewater disinfectant is mainly due to its effectiveness and ability to provide a low but measurable residual in the treated effluent. 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. Orange County's commitment at the South WRF is to sto re, 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. Accidental Release Prevention and Emergency Response Policies It is Orange County'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 the South Water Reclamation Facility. 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. South WRF's Plant Manager has the responsibility for ensuring that this program is implemented in the workplace as written. The South WRF emergency response plan relies on a team of offsite mutual-aid groups such as fire and rescue services. The emergency response plans at South WRF are based on the Incident Command system, where onsite responders work in coordination with local hazardous materials response teams to implement the South WRF and regional response plans. Stationary Source and Regulated Substances 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 thoro ughly 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. Several cylinders are connected to the disinfection process: half are in-use, and half are as standby. The standby cylinders will automatically switchover when the in-use cylinders become empty, ensuring continuous disinfection. The Worst-Case and Alternative Chlorine Release Scenarios As part of South WRF's emergency prevention and response efforts, a hazard assessment 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 South Regional WRF'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. Applying the worst-case parameters to the worst-case situation results in a distance to chlorine endpoint (defined as 0.0087 milligrams per liter) of 1.3 mile. 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. The scenario involved the release of chlorine gas through a failure of an lead washer on the gas cylinder valve connection. Response time is conservatively assumed to occur in 45 minutes. This scenario results in a distance to chlorine endpoint of less than 0.1 mile. The distance to endpoint calculations were performed using EPA's RMP*Comp model. The RMP*Comp model was developed specifically for compliance with the a ccidental release prevention requirement for predicting the travel distance of an accidental release. General Accidental Release Prevention Program and Specific Prevention Steps OCU'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. Training includes hazard awareness t raining on how to recognize a leak and initiate the Incident Command system. * Contractors: OCU ensures through its contract provisions that contractors supplying or working with chlorine are held to a standard of safety performance that complies with OCU's safety goals and objectives, and also meets relevant agency requirements. For example, OCU personnel make 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: OCU investigates within 48 hours any accidents or "near misse s" that could have resulted in a chlorine release, in order to develop measures to prevent a recurrence. The above elements are only part of OCU's aggressive safety program. In addition to the 13 PSM elements, OCU has established related OSHA safety programs such as hot work and confined space. These OSHA safety programs apply to both OCU and contractor employees. Five-year Accident History There have been two accidents involving chlorine in the past five years. One accident occurred in November 1997 and involved a poor lead washer seating, resulting in a 5 minute release. In response to this incident, OCU revised its chlorine change-out procedures and implemented additional training to all employees performing change-outs. Another accident occurred in February 1998 that resulted in an instantaneous release (a few seconds). In response to this release, OCU revised its procedures to isolate and properly vent a system that must be opened, updated its training programs, and impr oved the personal protective equipment relied on when working on the process. Emergency Response Program 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. |