Burbank Water Reclamation Plant Chlorination Stn. - Executive Summary |
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Chlorine is the most commonly used substance for disinfecting treated wastewater. City of Burbank Public Works Department (CBPWD) Burbank Water Reclamation Plant (BWRP) also stores and uses chlorine as part of the wastewater treatment process. Storing and handling large quantities of chlorine can create hazardous situations. BWRP takes its obligations in safely storing and using chlorine as seriously as it takes providing the environment safe disinfected water. BWRP has an excellent safety record in storing and handling chlorine. BWRP's chlorine handling process is subject to the U.S. Environmental Protection Agency (EPA) Risk Management Program and Plan and also to the California Accidental Release Prevention (CalARP) Program. These Programs require a summary of policies and procedures followed to safely operate the facility, including a description of the possible consequences in case of an accident and the actions which will be taken by the facility in an event of an emergency be included in the Risk Management Plan (RMP). The following information is specifically required in the RMP Executive Summary: 7 Accidental release prevention and emergency response policies. 7 General facility and regulated substances information. 7 Offsite consequence analysis results. 7 Summary of the accidental release prevention program and chemical-specific prevention steps. 7 Five-year accident history summary. 7 Emergency response program summary. 7 Planned changes to improve safety. The above information for the BWRP Chlorination System is provided below. Accidental Release Prevention and Emergency Response Policies BWRP accidental release prevention policy involves a unified approach that integrates proven technology, trains staff in operation and maintenance practices, and uses tested and proven management system practices. All applicable procedures of the State of California and EPA's Prevention Program are adhered to, including key elements such as training, systems management, and emergency action procedures. BWRP is a non-responding facility, which means that the facility employees will not respond to chlorine accidental release. Instead, the facility has coordinated with the local response agency to respond to any chlorine release that may occur at the plant. General Facility and Regulated Substance Information BWRP chlorination facility is located at 2 West Chestnut Street in Burbank, California. The water reclamation plant is located on a land area of approximately 6.5 acres, bounded on the east and north sides by Burbank-Western Flood Control Channel along with Southern Pacific railway and Golden State Freeway, on the west side by industrial area east of Victory Blvd., and on the south by an additional industrial area north of Magnolia Boulevard. BWRP was built in 1966 to treat wastewater; it was originally designed to process 6 million gallons of wastewater a day (6 mgd). BWRP capacity was increased to 9 mgd in 1976. Anhydrous ch lorine was used at the facility from 1966 to the first week of June 1999 to disinfect the BWRP treated effluents. The chlorination system consisted of eight ton-containers, weighing systems, chlorinators, a residual chlorine analyzer, and associated piping. As part of the expansion of the water reclamation plant, the City of Burbank proposed in 1993 to upgrade the chlorination facility. The upgraded chlorination facility is also designed to store up to a maximum of eight chlorine one ton-containers. The chlorination facility has been equipped with two evaporators, four chlorinators, injectors, chlorine detectors, and associated piping. In the upgraded chlorination system, liquid chlorine will be drawn off the connected ton-containers to the on-line evaporator and chlorinator. The chlorinator will automatically control the flow of the chlorine gas into the injectors located at four different application points where the gas will be dissolved into process water to make a chlorine s olution. This chlorine solution will then be introduced at the points of application. The chlorinated effluent will be detained in the contact tanks for the required disinfection time. A chlorine scrubber system has also been provided to neutralize any accidental chlorine release that may occur at the facility. The caustic scrubber system is able to neutralize the release of 4,800 pounds (more than two ton-containers load) of chlorine. Upon detection of chlorine gas by chlorine detectors, the scrubber system will be activated; chlorine leaking into the chlorine storage or chlorinator room will be ducted into a packed tower scrubber, and neutralized with recirculating caustic solution. The scrubber system is of once-through design, the maximum design discharge chlorine concentration from the scrubber stack would be 5 parts per million by volume. As mentioned above, the old chlorination station (using anhydrous chlorine ton-container system) operated till the first week of June 1 999. The anhydrous chlorine ton-container system was replaced by a temporary sodium hypochlorite system on June 7, 1999. Thus, there was no regulated substance present at the BWRP chlorination facility on June 21, 1999. The construction of the upgraded chlorination facility, including the chlorine scrubber system has been completed and anhydrous chlorine in quantities above the RMP threshold quantity of 2,500 pounds will be brought to the BWRP chlorination facility on August 10, 1999. The chlorination operation will be run continuously, 24 hours per day. Thus, BWRP will have one RMP covered process on August 10, 1999. Chlorine leak detectors are installed inside the chlorine building (in the chlorine storage as well as in the chlorinator room). The chlorine leak detection system continuously analyzes air samples from the chlorine storage and chlorination room. The detector system alarms locally as well as at the BWRP control room. The plant is manned 12 hours a day on weekda ys and 10 hours a day on weekends. The chlorine ton containers are stored inside a room which remains locked except when operators visit the facility. Offsite Consequence Analysis Results The offsite consequence analysis includes consideration of two release scenarios, identified as "worst-case release scenario" and "alternative release scenario". The first scenario is defined by EPA, which states that "the owner or operator shall assume that the ... maximum quantity in the largest vessel ... is released as a gas over 10-minutes," due to an unspecified failure. The alternative scenario is defined as "more likely to occur than the worst-case release scenario". RMP and CalARP regulations for Program 3 processes require the performance of a consequence analysis for one worst-case release scenario that is estimated to create the greatest distance in any direction to a toxic endpoint resulting from an accidental release of regulated toxic substances from covered processes. Only passive or administrative controls are allowed for this scenario to reduce offsite impacts. The release of one-ton (2,000 pounds) of chlorine over 10-minutes represents the worst-case release quantity for the single covered process at the BWRP. The release rate will thus be 200 lb./min. EPA and CalARP regulations require that the models used for dispersion analysis should appropriately account for the density of the released gas. Since the chlorine cloud formed during the worst-case release scenario would be denser-than-air, the Dense Gas Air Dispersion (DEGADIS 2.1) model was used for performing the air dispersion modeling analysis. The toxic endpoint selected by EPA and CalARP rules for chlorine is 3 ppm, which is the Emergency Response Planning Guideline Level 2 (ERPG-2). The toxic endpoint was conservatively set by EPA to ensure public notification and that local emergency response planning takes into account the greatest possible impacted area surrounding the release point. In prac tice, this type of a total failure of a one-ton container would be unlikely. EPA-mandated meteorological conditions, namely Stability F, wind speed of 1.5 m/sec, highest daily maximum temperature (1060F), and average humidity (61%) were used for the dispersion modeling analysis. The results of the dispersion modeling analysis indicated that the worst-case scenario has offsite impacts. RMP and CalARP rules require that a scenario, which results in offsite toxic endpoint distance and is more likely to occur than the worst-case scenario, should be selected as the alternative release scenario, unless no such scenario exists. Unlike the worst-case scenario, the alternative release scenario may consider "active" mitigation such as automatic shutoff valves, excess flow valves, and containment with scrubbers. Active mitigation is defined as requiring mechanical, electrical, or human input. Since chlorine is the only regulated toxic substance used at the facility, only one alternative sce nario was selected for the offsite consequence analysis. The scenario selected for the BWRP chlorination system involves the release of liquid chlorine from a crack in the pigtail connecting the ton-container to the chlorination process. It is assumed that the crack developed in the pigtail (diameter 0.25-inch) corresponds to a hole of 0.0625-inch (1/16 inch) diameter. The control room would have been warned of the chlorine leak by the chlorine detectors installed at the chlorination facility. It is assumed that a maximum of sixty minutes would be required for operators or an emergency response team to respond and shutoff the ton-container valve. The chlorine release rate inside the storage room was estimated at 10 lb./min. However, the chlorine release rate to the atmosphere from the scrubber would be only 0.003 lb/min. Since the chlorine release from the scrubber stack would be neutrally buoyant, EPA's SCREEN3 model was used for the air dispersion analysis. The meteorologi cal conditions used for the alternative release scenario analysis were Stability D, wind speed of 3.0 meters per second, average air temperature of 64 deg F, and average humidity of 61%. The results of the dispersion modeling analysis indicated that the maximum ground level one hour average concentration for chlorine would be approximately 0.03 ppm. This concentration is significantly lower than 3 ppm, the toxic endpoint for chlorine, and will have no offsite impacts. It may be noted that the occurrence of this scenario is highly unlikely because the pigtails are carefully inspected during each connection/disconnection operation, and during operator rounds. Finally, no chlorine release that could have caused safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at the BWRP during the last five years. Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps BWRP has prepared a Federal and State Process Safety Management Program. BWRP accidental release prevention program is based on the following key elements: 7 A management system 7 Detailed process safety information that is readily available to staff, emergency responders, and contractors. 7 A preventive maintenance program. 7 Performance of process hazard analysis of equipment and procedures with operation and maintenance staff participation and review. 7 Use of industry recommended process and safety equipment. 7 Use of effective operating procedures. 7 Training of the operators and maintenance staff. 7 Implementation of an incident investigation, inspection, and auditing program using qualified staff. Chemical-specific prevention steps include availability of self-contained breathing apparatus (SCBA), worn by the operators during connection/disconnection of chlorine supply, awareness of the hazardous and toxic properties of chlorine, presence of chlorine detectors and alarms, and a chlorine scrubb er. Process and Chemical Safety Information Chemical data have been assembled to include health hazard, and chemical exposure limitations, as well as detailed physical properties of chlorine. This information includes chlorine background information and MSDS sheets. Process Hazard Analysis In 1993, a detailed process hazard analysis (PHA) was conducted for the chlorination system equipment and procedures. A number of equipment and procedural changes were recommended as part of the PHA conducted in 1993. These recommendations have been implemented. In July 1999, the PHA for the chlorination system was further reviewed and will be updated again within a five-year period or whenever there is major change in the process. Twelve recommendations were made based on this PHA review; eleven recommendations have already been implemented. The twelfth recommendation will be implemented by August 31, 1999. A seismic walkthrough was recently completed based on the 1998 LEPC guidance docum ent. No new recommendations have been made based on this seismic walkthrough. Operating Procedures BWRP maintains written operating procedures that provide clear instructions for the chlorine process. The operating procedures include start-up, normal operation, and shutdown procedures. Operating procedures will be developed and put in place prior to any new process equipment coming on line or changes made in the handling of chlorine equipment, and reconfiguration of the facilities. Training BWRP employees presently involved in operating or maintaining the chlorine process are trained in an overview of the process and applicable operating and maintenance procedures. BWRP ensures that each employee newly assigned to the chlorine process, is trained and tested to be competent in the operating procedures listed pertaining to their duties. Each employee (presently involved in operating the chlorine process) has been trained to receive the required knowledge, skills, and abilities t o safely carry out the duties and responsibilities, including emergency response. Refresher training is provided annually to each employee operating the chlorine process to ensure that the employee understands and adheres to the current operating procedures. In addition, the BWRP ensures that operators are trained in any updated or new procedures prior to startup of a process after a major change as indicated in their Management of Change procedures. Contractors BWRP has procedures in place that ensures that the contractors are properly informed of the hazards, access limitations to the process area, and emergency response procedures, and prepared to safely complete the work. The contractors are informed, prior to the initiation of the work at the site, of the applicable provisions of the emergency response plan. Pre-Startup Safety Review and Mechanical Integrity Program BWRP ensures that a pre-startup safety review is completed for any new covered-by-the-rules process, or for s ignificant modifications to an existing covered process that requires a change in the process safety information. BWRP maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public, or the environment. BWRP mechanical integrity program includes the following: 7 Written procedures for maintaining mechanical integrity through inspection and testing of process equipment, based on instructions of equipment vendors, industry codes, and prior operating experience. 7 Implementation of the written procedures by performing inspections and tests on process equipment at specified intervals. 7 Training of maintenance personnel in preventive maintenance program procedures; safe work practices such as lockout/tagout, line or equipment opening, and avoidance and correction of unsafe conditions; and safe use and application of special equipment and/or unique tools. Hot Work Permits and Management of Change BWRP requires employee s and contractors to employ safe work practices when performing "hot work" in, on, or around the covered process. BWRP uses a permitting program to ensure hot work is conducted safely on or near a process involving chlorine. BWRP provides a system to maintain and implement any management of change or modifications to equipment, procedures, chemicals, and processing conditions. This system allows BWRP staff to identify and review safety hazards or provide additional safety, process, or chemical information to existing data before the proposed change would either compromise system safety or need training to be completed. Internal Compliance Audits Internal compliance audits will be conducted every 3 years to verify compliance with the programs and procedures contained in the RMP. The BWRP will assemble an audit team that will include personnel knowledgeable in the Risk Management Program rule and in the process. This team will evaluate whether the prevention program satisfies the r equirements of the Risk Management Program rule and whether the prevention program is sufficient to help ensure safe operation of the process. The results of the audit will be documented, recommendations resolved, and appropriate enhancements to the prevention program will be implemented. Incident Investigation BWRP investigates all incidents that could reasonably have resulted in a catastrophic release (serious injury to personnel, the public, or the environment) so that similar accidents can be prevented. An investigation team is assembled and the investigation is initiated within 48 hours of the incident. The results of the investigation are documented, recommendations are resolved, and appropriate process enhancements are implemented. Information found during the investigation is reviewed by affected staff and added or used to revise operating and maintenance procedures. Five-year Accident History Summary No chlorine releases that could have caused safety or health hazard ( deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at the BWRP during the last five years. Emergency Response Program Summary BWRP is a non-responding facility, which means that the facility employees will not respond to chlorine accidental release. Instead, the facility has coordinated with the local response agency to respond to any chlorine release that may occur at the plant. Planned Changes to Improve Safety Based on the 1999 PHA review, twelve changes to further improve chlorine safety were identified, including the update of the P&ID for the chlorine scrubber system. Eleven recommendations have already been implemented. The twelfth recommendation will be implemented by August 31, 1999. |