Rincon Chlorination Station - Executive Summary |
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EXECUTIVE SUMMARY The objectives of Casitas' accidental release prevention and emergency response policies are to prevent unwanted releases of chlorine gas which could expose employees and the public to serious hazards. Casitas' policies include review and controls on process design, operation and maintenance activities and procedures, emergency preparedness plans and training programs. Casitas' approach to safety as stated in the company Injury and Illness Prevention Program is as follows: It is the policy of Casitas Municipal Water District to strive for the highest safety and health standards on all projects and work assignments. Safety is the result of careful attention to all District policies and procedures by all employees and management personnel. Our safety program has been developed to assure compliance with federal, state, and local regulations, with emphasis on t he occupational safety and health act of 1970. We intend to prevent any human suffering as a result of accidents. Prevention of injury is a goal well worthy of our concern, diligence and job performance. Our employees have the right to a safe and healthful work environment. They also share the responsibility of working and acting in a safe manner. Our safety policy can be summarized into one sentence: "If it can't be done safely, we don't want you to do it." Casitas' three chlorination stations use chlorine gas liquefied under pressure to disinfect the community's water supply. Chlorine gas is drawn through piping under vacuum to injectors where the chlorine gas is mixed with water and then the solution is pumped into the pipeline. The locations of the chlorination stations are as follows: Casitas #1 - The chlorination station located at the base of Casitas Dam is used to inject chlorine into the p ipeline supplying Casitas' distribution system. Chlorine is brought to the site in one-ton containers. Six of these one-ton containers are connected to the dispensing system at any one time. Casitas #2 - The chlorination station located on the west side of Casitas Vista Road approximately .75 miles southeast of Casitas Dam. The facility is used to inject chlorine into the pipeline supplying Casitas' distribution system. Chlorine is brought to the facility in one-ton containers. Two of these one-ton containers are connected to the dispensing system at any one time. Rincon - The chlorination station located on the south side of Casitas Pass Road, approximately 0.9 miles west of Casitas Lake. The station is used to inject chlorine into the pipeline supplying the District's Rincon distribution system. Chlorine is brought to the facility in one-ton containers. One of the one-ton containers is connected to the dispensing system at any one time. The USEPA Risk Management Program (RMP) regulations require facilities with a regulated substance above the listed threshold quantities to prepare a formal Risk Management Program and submit a Risk Management Plan. The RMP consists of three major components; a hazard assessment, a prevention program and an emergency action plan. Additionally Casitas is subject to OSHA Process safety management and emergency action plan regulations, and State EPCRA laws. The hazard assessment portion of the RMP consists of assessment of hypothetical and alternative scenarios for the release of chlorine. The assessment includes dispersion modeling, identification of the area where chlorine gas levels can be above specified toxic end point criteria, and estimating potentially affected populations or sensitive environmental areas. To state it in simpler terms, the hazard assessment estimates the area of the downwind chlorine gas migration in the event of an accidental r elease from a chlorination facility. The hazard assessment was done for Casitas by an experienced consultant (Kazarians & Associates). The stream-valley topography surrounding Casitas #1 and #2 chlorination stations does not directly correspond to the "rural" or "urban" designations that are used for modeling purposes. Rural topography is characterized by a lack of buildings or obstacles that would create air turbulence and mixing. Urban topography is characterized by buildings or other obstacles (trees) that create turbulence and increase air movement. This increases atmospheric mixing and results in the computation of a lower distance to toxic endpoint for a given release than rural topography would. In Casitas' situation, the trees and other obstacles increase air turbulence and mixing, but the stream valley could confine a chlorine gas release and direct the release cloud downhill. For this reason, rural distances to endpoint were used instead of the rel atively lower urban distances when calculating the area of down wind gas migration. The required worst case release scenario is extremely unlikely due to the fact that it specifies using the maximum amount of chlorine contained in one cylinder (2000 lbs) to be released during a ten minute period. The most likely cause for a release of this magnitude would be a catastrophic event. Regulatory agencies recognize that the worst case scenario may represent a highly improbable scenario which may not be appropriate for emergency planning. The alternative scenarios are those that are more credible and more appropriate for emergency planning. The one-ton containers are stored in an enclosed building that would slow down the release of chlorine gas. The estimated distance of toxic levels of chlorine gas from the chlorination stations was calculated from the EPA Risk Management Program Guidance for Wastewater Treatment Plants. The alternative scenario is also unlikely, but more likely to occur than the worst case, because the alternative scenario can be based on an equipment failure. The intent is to select a credible scenario that provides a basis for planning on-site emergency response and off-site community response. The alternative scenario chosen for this analysis is the failure of the lowest fusible plug on the chlorine cylinder, causing the release of liquid chlorine into the chlorination room. This scenario was chosen because it would result in a larger release quantity than a chlorine gas leak near the top of the cylinder. It is unlikely that a leak towards the top of the cylinder would release the full amount in the cylinder. The reason being that if a leak occurs above the liquid level in a pressurized cylinder, the chemical properties of chlorine (high vapor pressure and low boiling point) will cause frost to form on the vessel in the area of the leak forming a barrier that stops the vaporizati on. Another safety feature that minimizes the likelihood of a major release is that the chlorine gas piping from the cylinders to the injectors is operated under vacuum. The chlorine injectors operate using the venturi principle, which generates a vacuum in the chlorine gas line; this vacuum opens the valve to the chlorine container, and allows the gas to flow. Additional manual valves are used as flow regulators. If vacuum is lost (piping damage) the vacuum actuated flow valve will close and this will stop the gas flow and isolate the chlorine container. To further enhance safety, the chlorination facilities are enclosed in concrete block buildings that would slow the release of chlorine to the surrounding environment. This is termed passive mitigation, and was accounted for when calculating release scenarios. Offsite impacts were predicted from both the worst case and alternative release scenarios. To ensure an immediate response by district person nel to a chlorine release, a chlorine gas detector is located inside of each chlorination station. Should a chlorine release occur, the gas detector immediately initiates an audible alarm and warning beacon at the chlorine station. Alarms are also actuated at the nearby treatment plant at Casitas dam and at the district office in Oak View, and an on-call operator who is available 24 hours a day is paged. The emergency warning system is tested by District technicians once a month. The warning system is on an emergency back-up generator in the event of a power loss. All equipment used for dispensing chlorine receives a preventative maintenance overhaul every year. The second major component of the RMP is the prevention program. The goal of the prevention program is to reduce the risk injury or death to employees and the public from accidental release of chemicals. The prevention program consists of the following elements: Documentation of process safety information for the chlorination process at the three sites. Process safety information assists the employees in understanding the chlorination process so that they can operate in a safe and efficient manner. A Process Hazard Analysis has been done to identify potential hazard and operability concerns. The Process Hazard Analysis contains recommendations to reduce the risk of potential hazards or accidental releases, and to comply with the regulations. Casitas maintains current and accurate operating procedures that provide clear instructions for the chlorination process. Operating procedures when combined with operator training ensure safe operation of the chlorination process and prevent accidental releases. The Casitas training program ensures that personnel are adequately trained and understand inherent hazards and appropriate response actions to accidental chemical releases. The mechanical integrity program ensures the continued integrity of the chlorination process equipment. This program is integral to the prevention of accidental chemical releases that may result from mechanical failure of improperly maintained equipment. The management of change procedure ensures that chlorine system changes are properly reviewed against original system design specifications. It ensures that changes can be accomplished safely and that systems are ready to operate safely in accordance with original system design intent following implementation of the change. Prestartup reviews will be performed when modification of the chlorination process is significant enough to require a change in the process safety information. Prestartup reviews ensure that Casitas is ready to safely operate new and modified chlorination processes. Compliance audits will be per formed to process safety and risk management programs and their implementation for OSHA PSM and EPA RMP regulations. Whenever necessary the, audit will identify recommendations to address program deficiencies. All incidents at the Chlorination facilities which could have resulted in or reasonably resulted in a release of chlorine, will be promptly investigated. The purpose of the investigation is to identify the underlying causes of an incident and to implement corrective actions to prevent the incident from reoccurring. Casitas recognizes that it is essential to have it's employees involved in the development and implementation of an OSHA PSM and EPA RMProgram. The employee recognition program defines how the employees will be involved. The hot work permit procedure insures that a hot work permit will be required for all hot work operations (welding, torch cutting etc.) conducted on or near the chlorination processes. Only contractors with good health and safety programs will be selected to perform work on or around the chlorination process. The contractors and the chlorination process must be properly prepared to safely complete the work. The management system ensures that everyone who is involved with the RMProgram understands their roles and responsibilities and that responsibilities are assigned for all of the program elements. The third major component of the RMP is the Emergency Action Plan. The purpose of Casitas' Emergency Action Plan is to minimize the duration and effects of an accidental release of chlorine. For minor releases where there is clearly no potential for safety or health hazard, the release will be controlled by the employees and will be considered an incidental release. If a release is progressing so that a hazard is imminent, the event must be considered a release and t he Emergency Action Plan will be initiated. The Emergency Action Plan includes Casitas in the community emergency response plan, and specifies the appropriate mechanisms for notifying emergency responders. The Emergency Action Plan includes specific actions to be taken in response to releases of chlorine such as notification of the Plant Supervisor or Chief Operator, and notification to the Office of Emergency services (OES). OES will in turn notify the County of Ventura Environmental Health Department. If it becomes necessary, Ventura County Fire Department and Ventura County Sheriffs Office will be notified to handle evacuations, but during an extreme emergency saving lives is more important than procedure. Casitas is pleased to report that at all three chlorination Stations there have not been any events during the previous five years that had any potential for generating a significant accidental release. Addressing the recommendations developed from the Process Hazard Analysis is the top priority for planned changes to improve safety in the near future. Casitas will continue its policy to address and review all safety concerns as necessary. The Risk Management Plan will be updated and resubmitted as required by the regulations. OFFSITE IMPACTS Chlorination Site Release Scenario Distance to Toxic Endpoint Residential Population within the Circle Sensitive Receptors Environmental Receptors Casitas #1 Worst Case Alternative 2.25 miles 0.4 miles 1,349 16 Arnaz Elementary School -Lake Casitas Recreation Area -Foster County Park Casitas #2 Worst Case Alternative 2.25 miles 0.4 miles 1,196 78 Arnaz Elementary School -Lake Casitas Recreation Area -Foster County Park Rincon Worst Case Alternative 2.25 miles 0.4 miles 80 17 Los Padres National Forest Los Padres Nation Forest |