Simi Valley Water Quality Control Plant - Executive Summary |
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Introduction Chemicals are widely used in industry, in the home, in the environment. They are transported on roads, water, and railways. We at the Simi Valley Water Quality Control Plant (Simi Valley WQCP) use chemicals, too. For example, we use chlorine to disinfect our water to provide safe water discharges to the environment or for landscaping or irrigation uses. Storing large qualities of chlorine can be a hazard. We take our safety obligations in storing and using chlorine as seriously as we take providing the environment safe disinfected water. The following document describes what could happen if there were to be an accident, the steps we take everyday to ensure a safely operating plant, and what to do in event of an emergency. Please feel free to contact Deputy Director/Sanitation Services at Simi Valley WQCP if you have any questions. Accidental Release Prevention and Emergency Response Policies The City of Simi Valley and the Simi Valley WQCP accidental release pre vention policy involves a unified approach that integrates proven technology, trains staff on operation and maintenance practices, and uses tested management system practices. All applicable procedures of the State of California and U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to, including key elements such as training, systems management, and emergency response procedures. In fact, Simi Valley WQCP won three consecutive Tri-County Plant of the Year Awards. Most recently, in 1995, Simi Valley WQCP received the State Plant of the Year Award for plants greater than 10 million gallons per day (mgd). This document complies with the U.S. Environmental Protection Agency's (EPA's) Risk Management Program, under Section 112 (r) of the Clean Air Act (CAA) Amendments of 1990, 40 Code of Federal Regulations (CFR) Part 68 and the California Accidental Release Prevention (CalARP) Program under California Code of Regulations (CCF) Title 19, Division 2, Chapter 4.5. The Simi Valley WQCP has a chlorination system that uses chlorine gas fed from liquid chlorine containers. This document summarizes our existing health and safety programs, our internal response policies, procedures, and on-going actions that are designed to prevent or minimize impacts of accidental releases of chlorine to the environment. The Simi Valley WQCP has prepared a detailed and comprehensive emergency response plan to handle any potential accidental releases and is designed to safeguard both on- and off-site people. To date, we have had an excellent record in preventing accidents from occurring. General Facility and Regulated Substances Information The Simi Valley County Sanitation District Water Quality Control Plant is a tertiary water treatment facility. Wastewater, collected from homes, businesses and industries, flows via the City of Simi Valley's sewer system to the WQCP. The plant is located at the west end of the city at 600 West Los Angeles Avenue. The Sim i Valley WQCP treats both the liquid and solid constituents found in the wastewater. The process of wastewater treatment can be divided into four general categories: preliminary treatment, primary treatment, secondary treatment, and tertiary treatment. The processes include: 7 Mechanical Bar Screens 7 Grit Removal Facilities 7 Primary Sedimentation Tanks 7 Flow Equalization 7 Rotating Biological Contactors 7 Activated Sludge Treatment 7 Secondary Sedimentation 7 Anaerobic Digestion 7 Dual Media Filtration 7 Chlorination The final treated water is discharged to the Arroyo Simi, which forms the southern boundary of the treatment plant site. The facility currently stores chlorine, a regulated substance under RMP and CalARP. The chlorination system at Simi Valley WQCP is the main part of the tertiary wastewater treatment system. The chlorination system converts liquid chlorine to chlorine gas and injects the gas into a solution that is used in several plant processes, primarily for final effluent disinfection. Liquid chlorine is stored in a 25-ton (5,000 gallon) bulk chlorine storage tank that stores up to 40,000 pounds of chlorine, and in four one-ton cylinders. During normal operations, only the bulk storage tank is used, and the one-ton cylinders are in standby. Chlorine flows form the bulk storage tank to evaporators under pressure where a hot water bath is used to raise the liquid temperature to convert the liquid to a gas. A vacuum is created in an ejector that pulls the gaseous chlorine through chlorinators that control and measure the flow of gaseous chlorine. The gaseous chlorine is mixed with plant effluent water, and the solution is distributed to several locations in the plant. Additional safety systems include the following: Leak Detection. Three leak detectors located at the chlorination facilities: one is located at the chlorine storage facilities between the chlorine bulk storage tank and the empty sulfur dioxide bulk storage tank. The second leak detector is located on the west wall of the chlorination room, and the third one is located near the one-ton cylinders. If the leak detector detects chlorine gas in the chlorination room, the leak detector automatically activates two wall mounted exhaust fans on the east wall of the room. In addition, the leak detector activates four solid red lights, and one flashing red light, one over each doorway in the chlorination building. It activates a horn over the southeast corner of the building. Third, the leak detector activates and annunciator for the Chlorination Room at local control panel and at the main control panel in the Operations Building. If a chlorine leak occurs in the storage area, the leak detector activates the horn and four flashing red lights. A light is mounted on each side of the rectangular cover, which covers the containers and storage tanks. The leak detection also activates an annunciator for the storage area at local control panel and at the m ain control panel in the Operations Building. The chlorine leak detectors have a DANGER level light and an ALARM level light. When chlorine is detected, the sensor activates the DANGER light fires and then the ALARM light. The set-point for the ALARM light is 1 ppm. Automatic Shutoff Valve. An automatic shutoff valve is mounted on the liquid chlorine line that extends from the bulk storage tank to the evaporators. If a leak in the supply line should develop, a low pressure switch automatically closes the automatic valve too prevent further leakage from the bulk storage tank. In addition, the low pressure switch activates an annunciator at the local control panel in the Chlorination Building. Pressure Relief Valve. The chlorine bulk storage tank is equipped with a pressure relief valve that is set to discharge at 225 psig. A pressure relief valve and rupture disc are also mounted on the chlorine gas line where the chlorine gas exists the evaporator. The rupture disc is set t o rupture at 400 psig, and the relief valve is set to vent at 560 psig. The relieved gas from the relief valve is discharged to the chlorine vent piping . Rupture Disks and Expansion Chambers. The liquid chlorine fill line and withdrawal lines to and from the bulk storage tank are equipped with expansion tanks and rupture discs. If chlorine is trapped in the fill and withdrawal line, and the pressure rises above the rupture disc pressure of 400 psig, the disc ruptures and the expansion tank provides additional volume for reducing the line pressure. If the rupture disc fails, a pressure switch on the expansion tank will indicate a high pressure condition at the local control panel for chlorination in the chlorination building. Excess Flow Valves. The lines for withdrawing liquid chlorine, which extend to the bottom of the chlorine bulk storage tank, are equipped with excess flow check valves. If the chlorine flow exceeds 7000 lb/hr, the excess flow check valve shuts off the li ne. If a shutoff valve breaks off, the excess flow check valve will prevent leakage. Fusible Plugs. All ton containers are equipped with fusible metal type safety relief devices, called fusible plugs. Most ton containers have six fusible plugs, three at each end, spaced 120 degrees apart. In the event of a fire or other high temperatures, the fusible plug is designed to melt between 150 F and 165 F to relieve pressure and prevent a catastrophic rupture of the container. Vacuum Regulator. The chlorine gas exiting the evaporator is under pressure. After the chlorine gas exits the evaporator and is filtered, it flows through an automatic shutoff valve/ vacuum regulator, which regulates the transition from gas flow under pressure to gas flow under vacuum. If a low water bath temperature develops at the evaporator, the liquid chlorine may not be thoroughly heated to produce the chlorine gas. If this condition occurs, the automatic shutoff valve closes to prevent liquid chlorine f rom being drawn into the vacuum lines and chlorinator. This valve shuts off if temperature drops below 1500F. Chlorinator Vacuum Switches. Each chlorinator has vacuum switches for sensing high vacuum and loss of vacuum. If the ejector draws excessive vacuum, the high vacuum switch activates a high vacuum annunciator at the local control panel. If there is a leak or a break in the vacuum lines delivering chlorine to the ejectors, the vacuum regulator shuts off and the loss of vacuum switch activates a loss of vacuum annunciator at the local control panel. Air Pack. Several 30 minute SCBAs are stored in the safety storage container located west of the Administration/Operations Building. Air is also supplied to operators by a tether system located at the chlorine building. The tether system consists of a 50-ft hose, two air tanks, and hookups in the bulk storage area and in the chlorinator room. Simi Valley personnel use air supplied by the tether system during 1-ton container l oading, unloading, and changeout. The SCBA are also worn during these tasks as emergency backup and during delivery of chlorine to the bulk tank. Emergency Shower and Eyewash. An emergency eyewash is provided outside, on the south wall of the chlorination building adjacent to the door. A metal grating plate activates the shower and eyewash. The grate is tilted upward and held in place with a chain. If any weight is placed on the grating, the chain opens the valve, which starts the flow of water. Fire Extinguishers. There are five multipurpose fire extinguishers in the chlorination building. One fire extinguisher is located adjacent to each doorway. Repair Kits. Two chlorine repair kits are stored in the chlorination building. The Chlorine Institute Type B repair kit for the 1-ton containers is designed to repair leaks at container valves, fusible plugs, or minor leaks in the ton containers themselves. The Chlorine Institute Type C repair kit for bulk storage tanks is desig ned to repair leaks at the angle shut-off valves and the pressure relief valve. Other Safety Systems. A storage room adjacent to the Control Room in the chlorination building houses the air bottles, chlorine emergency repair kits, and miscellaneous safety equipment and appurtenances. A windsock is located on top the filters directly east of the chlorine storage facilities. The windsock provides an immediate indication of the wind direction and subsequent direction of a potential gas leak. Another windsock is located on digester number 3, north of the chlorine building. All conditions annunciated at the local control panel in the Chlorination Building are grouped together to activate a common alarm for chlorination at the main control panel in the Operations Building. Access to the Simi Valley WQCP is controlled with a fence and a gate, which is locked between 5 p.m. and 7 a.m. The chlorination room is remains locked when not in use. Offsite Consequence Analysis Results The of fsite consequence analysis includes consideration of two release scenarios, identified as "worst case" and "alternative" release scenarios. The worst-case scenario requires that the release of the entire contents of the single largest vessel or pipe be evaluated for offsite impacts from chlorine. Only passive or administrative controls are allowed to reduce off-site impacts under the worst-case release scenario. The worst-case release scenario used for Simi Valley WQCP is the rupture of the chlorine bulk storage tank, and the release of the entire contents in 10 minutes. Administrative controls are used to limit the filling of the bulk tank to only 40,000 lbs. The release rate will, accordingly, be 4,000 pounds per minute (lbs/min). In practice this type of total release of a bulk tank would be unlikely and never occur during the lifetime of the plant. The released liquid is assumed to quickly volatilize and to disperse as a vapor cloud. The distance to the toxic endpoint was es timated using the EPA model DEGADIS, version 3.0.3. The toxic endpoint was conservatively set by EPA to ensure public notification and that local emergency respond planning takes into account the greatest possible impacted area surrounding the release point. The toxic endpoint selected by EPA and CalARP was 3 ppm. In addition all required EPA-model input parameters where included in completing this activity, including conservative meteorological conditions - Stability F class, wind speed of 1.5 meters per second, highest daily maximum temperature (110 degree F), and average humidity (64 percent). The results of the dispersion modeling analysis for this worst case release scenario indicate that this scenario has an offsite impact. The alternative release scenario is more likely to occur than the worst-case release scenario. Unlike the worst case release scenario, active controls can be applied to minimize the leak or impacts. Active controls consist of mechanical, electrical, or h uman input. The alternate release scenario considered was a chlorine release resulting from a leak in a valve packing located inside the chlorination building. Because the release is assumed to occur inside a building, building mitigation was used for this scenario. Under this scenario, the amount of chlorine released was calculated to be 5.56 lbs./min. The same modeling approach was used as for the worst case release scenario, except meteorological conditions were adjusted to more common conditions of Stability D Class, wind speed of 3.3 meters per second, average air temperature of 67 degrees F, and average humidity of 64 percent. The results of the dispersion modeling analysis indicate that the alternative release scenario has an offsite impact. Finally, no chlorine releases that could have caused safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at Simi Valley WQCP during the last 5 years. Some minor, incidental releases may have occurred over this period, but they were quickly handled by staff, were neutralized, or posed no safety or health hazards. Summary of the Accidental Release Prevention Program and Chemical-specific Prevention Steps Simi Valley WQCP is in compliance with Federal and State Process Safety Management (PSM) requirements. Chemical-specific prevention steps include availability of self-contained escape breathing apparatus, worn by the operators during connection and disconnection of the chlorine supplies, awareness of the hazardous and toxic properties of chlorine, and the presence of chlorine and detectors and alarms. Simi Valley WQCP accidental release prevention program is based on the following key elements: 7 Detailed management system and clear levels of responsibilities and team member roles 7 Comprehensive safety process information that is readily available to staff, emergency responders, and contractors 7 Comprehensive preventive maintenance progr am 7 Completed a process hazard analysis of equipment and procedures with operation and maintenance staff participation and review. 7 Use of state-of-the-art process and safety equipment 7 Use of accurate and effective operating procedures, written with operations and maintenance staff participation 7 High level of training of operators and maintenance staff 7 Implementation of an incident investigation, inspection, and auditing program using qualified staff. Process and Chemical Safety Information Comprehensive chemical data have been assembled to include regulatory reporting and action thresholds, health hazard, and chemical exposure limitations, as well as detailed physical properties of each regulated substance. This information was compiled from numerous sources and is intended to be a one-stop source for the reader seeking data about these substances. This information includes chlorine background information, MSDS sheets, and chlorine reaction chemistry. Equipment safety inf ormation was meticulously compiled on the chlorine process. Specifications for each process are collected in one place for easy reference. Details such as maximum intended inventory; safe upper and lower temperatures; safe upper and lower pressures; and codes and standards used to design, build, and operate the processes are on file at the facility. We also have procedures in place that is triggered to update safety information if there is a major change that makes existing information inaccurate. Process Hazard Analysis On March 25, 1999, a detailed process hazard analysis (PHA) was conducted with plant staff, engineering, and management staff for the regulated process. The team consisted of process operating and maintenance experts and process design engineers. The PHA technique used was the "What-if?" study, per acceptable approach guidance from EPA. The PHA was lead by knowledgeable person on the type of process being reviewed. This review will be updated within a five-y ear period or whenever there is major change in the process. A list of actions to resolve any found significant hazard review findings was prepared and staff is currently working to resolve this action item list. Staff will document completion of any action item. A seismic walkthrough was recently completed based on the 1997 UBC, and recommendations were provided to Simi Valley WQCP for their evaluations and implementation. Operating Procedures Simi Valley WQCP maintains up-to-date, accurate, written operating procedures that give clear instructions for the chlorine and sulfur dioxide processes. Simi Valley WQCP ensures effective operating practices by combining them with operating and maintenance training programs. Standard operating procedures (SOPs) provide system descriptions, specifications, equipment inspection requirements, and operating procedures for the chlorine system. Procedures include startup, shutdown, and normal, and emergency operation. Also included is main tenance and troubleshooting procedures, including consequences of deviation and the steps to avoid correct deviations. Simi Valley WQCP will update procedures whenever a change occurs that alters the steps needed to operate safely. Operating procedures will be developed and in place prior to any new process equipment coming on line or a changed process starting back up. Operations and Maintenance Training Program Each Simi Valley WQCP employee presently involved in operating or maintaining the chlorine process are trained in an overview of the process and detailed, applicable operating and maintenance procedures. In fact, Simi Valley WQCP helps their employees understand through training the nature and cause of problems arising from operations involving chlorine on site, and to increase their employees awareness with respect to their hazards. Simi Valley WQCP's training program includes both initial and refresher training that covers 1) a general overview of the processes, 2) the properties and hazards of the substances in the process, and 3) a detailed review of the process operating procedures and safe work practices. Oral reviews and written self-evaluations are used to verify that an employee understands the training material before the process work can be resumed. Training documentation includes: date of most recent review or revision to the training program, type of training required and the type of competency testing used to ensure staff understands the training. Contractors Simi Valley WQCP has procedures and policies in place that ensure that only contractors with good safety programs are selected to perform work on and around the chlorine process and that the contractors are properly informed of the hazards, access limitations to these process areas, and emergency response procedures, and prepared to safely complete the work. Simi Valley WQCP sets minimum contractor safety performance requirements to do work at the Simi Valley WQCP, holds cont ractor safety briefings before allowing them near or in the process area; controls access to the process areas, and evaluate the contractor's performance. Pre-Startup Safety Review and Mechanical Integrity Program Simi Valley WQCP ensures that a pre-startup safety review is completed for any new process regulated under CalARP or PSM regulations at the plant, or for significant modifications to an existing covered process that requires a change in the process safety information. Simi Valley WQCP maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public, or the environment. Simi Valley WQCP believes that this program is the primary line of defense against a release and addresses equipment testing and inspection, preventative maintenance schedules, and personnel training. Simi Valley WQCP's mechanical integrity program includes the following: 7 Written procedures for maintaining mechanical integrity through in spection 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 procedures for safe work practices such as lockout/tagout, line or equipment opening, and avoidance and correction of unsafe conditions 7 Procedures specifying training requirements for contract maintenance employees, as well as requiring contractors to use plant developed maintenance procedures for process areas. Hot Work Permits and Management of Change Simi Valley WQCP requires employees and contractors to employ safe work practices when performing "hot work" in, on, or around the covered processes. Simi Valley WQCP uses a comprehensive permitting and training program to ensure hot work is conducted safely. Simi Valley WQCP provides a system and approach to maintain and implement any mana gement of changes or modifications to equipment, procedures, chemicals, and processing conditions. This system allows Simi Valley WQCP employees to identify and review safety hazards or provide addition safety, process, or chemical information to existing data before the proposed change would either comprise system safety or need training to be completed. Internal Compliance Audits Internal compliance audits are conducted every 3 years to verify compliance with the programs and procedures contained in the RMP. Simi Valley WQCP assemble an audit team that includes personnel knowledgeable in the Risk Management Program rule and in the process, and this team evaluates whether the prevention program satisfies the requirements 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 are documented, recommendations are resolved, and appropriate enhancements to the prevention program are im plemented. Incident Investigation Simi Valley WQCP investigates all incidents that could reasonably have resulted in a serious injury to personnel, the public, or the environment so that similar accidents can be prevented. Simi Valley WQCP trains employees to identify and report any incident that requires investigation. 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, added or used to revise operating and maintenance procedures, and passed onto the training unit for their inclusion in existing training programs, if warranted to prevent a future event. Five-year Accident History Summary No chlorine release that could have cause safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at Simi Valley WQCP during the last five years. Emergency Response Program Summary Simi Valley WQCP has established a written emergency response program that is followed by the employees to help safely respond to accidental releases of hazardous substances. This program has been coordinated (reviewed) by the Ventura County Fire Department, which is a member of the Local Emergency Response Planning Committee (LEPC). This program includes an emergency response notification plan. Emergency response drills and drill evaluations are conducted every 12 months; emergency operation and response procedures are also reviewed at that time. Planned Changes to Improve Safety The safety of the chlorine process was reviewed in March 1999 in the process hazard analysis. Based on these reviews, additional changes were identified to improve the safety of the chlorination system. A study is currently being performed on replacing the gaseous chlorine process with a less toxic liquid sodium hypochlorite system (similar to household bleach). A decision on the removal of the chlorine system is expected by September 1999. It is expected that the remainder of the recommended actions will be evaluated and implemented by January 30, 2000. The implementation of these recommendations will further improve the safety of the covered processes. |