REGIONAL PLANT #1 - Executive Summary |
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EXECUTIVE SUMMARY This document comprises the Risk Management Plan (RMP) for the Inland Empire Utilities Agency (Agency) facility located at 2662 East Walnut Street in Ontario California 91761 (also referred to within the Agency as Regional Plant No. 1, RP-1). RP-1 also houses Tertiary Plant 1 (TP-1). RP-1 (and the adjacent TP-I) is located in Ontario, California near the intersection of California Route 60 and Archibald Avenue and occupies approximately 66.06 acres of land divided by the Cucamonga Creek Drainage Channel. RP-1 occupies the northwestern portion of the property while TP-I occupies the southeastern portion of the property. The Agency also operates two other stationary sources subject to the federal RMP/CalARP regulations. Separate RMPs have been submitted for those facilities. The purpose of this document is to comply with the risk management planning requirements as set forth in Section 25535(d) of Article 2 of Chapter 6.95 of the California Health and Safety Code (als o known as the California Accidental Release Prevention Program - CalARP) and Part 68 of Title 40 of the Code of Federal Regulations (40CFR Part 68), also known as the federal Accidental Release Prevention Requirements: Risk Management Programs or the federal RMP. The scope of the RMP includes all operations conducted at the RP-1 facility which involve the storage, handling and/or use of chlorine and methane (which is contained in digester gas). Chlorine and methane (which is contained in digester gas) are the only regulated substances which are handled at the facility above the threshold quantity. ES 1.0 DESCRIPTION OF STATIONARY SOURCE AND REGULATED SUBSTANCES HANDLED Since its inception, the Inland Empire Utilities Agency has evolved with the growth and needs of the western portion of San Bernardino County. Today, the Agency distributes imported water and provides municipal/industrial wastewater collection and treatment services for a 242-square mile area that includes more tha n 600,000 people. RP-I has been in operation since 1948 and serves the cities of Ontario, Rancho Cucamonga, Upland, Montclair, Fontana and some unincorporated portions of San Bernardino County in California. The primary operation conducted at RP-I is wastewater treatment. As a part of this process, chlorine is utilized for water disinfection and digester gas (which contains methane) is generated in the anaerobic digesters (anaerobic digesters are operated in the absence of oxygen). Currently, the plant treats approximately 44 million gallons of wastewater per day. Provided below, is a brief description of the primary operations conducted at the facility and a description of the storage, handling and use of chlorine and digester gas. PRIMARY OPERATIONS Figure ES-I provides a simplified process flow diagram for the wastewater treatment process at RP-I. As shown, raw sewage is passed through screening and grit removal units, primary clarifiers, aeration basins, secondary clarifiers, ch emical addition, tertiary filters, chlorination and dechlorination units and then discharged. The plant effluent is utilized for irrigation of the Whispering Lakes Golf Course and Westwind Park in the City of Ontario and to supply water to the Prado Regional Park Lake in southwestern San Bernardino County. In addition, plant effluent is discharged to the Cucamonga Creek Flood Control Channel and onto the Santa Ana River. RP-I contains three aeration basins, seven anaerobic digesters, twelve primary clarifiers, one trickling filter, six secondary clarifiers, and a maximum of two one ton containers of chlorine. The adjacent TP-I contains three flow equalization basins, the tertiary filters, a pump station, and two bulk chlorine storage tanks. STORAGE, HANDLING AND USE OF CHLORINE TP-I Chlorination Process Description At TP-I chlorine is utilized to disinfect cleaned/treated water prior to discharging (this is also known as final disinfection of the effluent). Chlorine is a regulated substance subject to the federal RMP requirements. The TP-I chlorination process consists of four main components: 7 Two 7,000 gallon capacity bulk storage tanks (i.e., each bulk storage tank has a capacity of approximately 70,000 pounds of chlorine); 7 Three evaporators for converting liquid chlorine to a gaseous state; 7 Four chlorinators and ejectors to control the injection of chlorine and maintain a vacuum on the gaseous chlorine system; and 7 System piping. Liquid chlorine is delivered to the facility via tank truck and downloaded into the two chlorine bulk storage tanks. Liquid chlorine is then withdrawn from the storage tanks and transferred to the evaporators under pressure exerted by the contents of the storage tanks. The evaporators provide the heat necessary to vaporize chlorine (the evaporators are heat exchangers which circulate hot water through a jacket around the chlorine evaporation chamber). The chlorine gas generated by the evaporators is transferred t o the chlorinators under a vacuum and injected into water (now referred to as chlorine solution). The vacuum from the evaporators to the injection point is maintained by the ejectors. As a result of having chlorine injected into it, the water contains elevated levels of diluted chlorine. This chlorine solution is then transferred via underground piping to the two end use points where it is mixed with the water to be disinfected. The entire process (i.e., the bulk storage tanks, the evaporators, the chlorinators and the ejectors) is located within a separate dedicated building designed specifically for the purpose of housing this system. Emergency Chlorine Scrubber at TP-I The Agency has installed an emergency chlorine scrubber. This unit is connected to the bulk chlorine storage building (where both bulk chlorine storage tanks, the evaporators and the chlorinators and ejectors are housed). Under emergency conditions, an induced draft fan pulls the chlorine (released into the building ) through the scrubber, where intimate contact with a re-circulating solution of sodium hydroxide (i.e., 50-percent concentrated sodium hydroxide) results in complete absorption and removal of chlorine vapor. The unit has the capacity to scrub up to 2000 pounds of chlorine and is activated via either automatic leak detectors (i.e., chlorine sensors located within the building) or a manual remote start switch. RP-I Chlorination Process Description At RP-I, the quality of water is monitored via sampling of the process. Chlorine is periodically utilized (on an as-needed basis depending upon the results of the water sampling) to control the growth of organisms in the activated sludge process and to control sludge settling in the gravity thickener, and to reduce/control odor in the plant influent flow. Chlorine is a regulated substance subject to the federal RMP requirements. The RP-I chlorination process consists of four main components: 7 Two one-ton containers of chlorine; 7 One evap orator for converting liquid chlorine to a gaseous state; 7 One chlorinator and five ejectors to control the injection of chlorine and maintain a vacuum on the gaseous chlorine system; and 7 System piping. One ton containers containing liquid chlorine are delivered to the facility via truck and stored. Liquid chlorine is then withdrawn from the containers and transferred to the evaporators under pressure. The evaporator provides the heat necessary to vaporize chlorine (the evaporator is a heat exchanger which circulates hot water through a jacket around the chlorine evaporation chamber). The chlorine gas generated by the evaporator is transferred to the chlorinator under a vacuum and injected into water (now referred to as chlorine solution). The vacuum from the evaporator to the injection point is maintained by the ejectors. As a result of having chlorine injected into it, the water contains elevated levels of diluted chlorine. This chlorine solution is then transferred via undergr ound piping to the three end use points where it is mixed with the water to be treated. STORAGE, HANDLING AND USE OF METHANE RP- I Anaerobic Digestion and Digester Gas Production Process Description Solids removed from the liquid treatment processes are thickened and stabilized in anaerobic digesters. Anaerobic digestion is accomplished by retaining the sludge in the absence of oxygen within the large, airtight digestion tanks for a period of 20 to 25 days. Within these tanks, microorganisms digest the sludge and convert the solids into cells and continuously produces gaseous byproducts. These gaseous byproducts are known as digester gas and contain methane, carbon dioxide and other gases. Methane is a regulated substance subject to the federal RMP requirements. The gas rises to the top of each digester and is collected for recirculation to the digester (to provide mixing). In addition, digester gas is utilized to power onsite cogenerators and provide an average of 675,000 kilowatt h ours of electricity each month. This significantly reduces the cost of purchasing electrical power from Southern California Edison. . Excess gas is collected and burned in the waste gas burner (i.e., flare). ES 2.0 ACCIDENTAL RELEASE SCENARIOS The RMP regulations require that at least two types of release scenarios be evaluated for their potential to impact off-site populations: 7 the worst case release; and 7 an alternative release (that is more credible). A number of hypothetical accidental release scenarios were postulated and evaluated for the RMP. These scenarios were categorized into worst-case release scenarios and alternative release scenarios. Each of these categories of hypothetical accidental release scenarios is discussed below. CHLORINE Worst-Case Release Scenario In this scenario, one of the two bulk chlorine storage tanks on site experiences a catastrophic failure due to an unknown external event. This scenario would be initiated by some unknown external event (i .e., an airplane, missile or meteorite impacting the chlorine building where the tanks are located). It is highly improbable that this scenario would be initiated by a seismic event. The chlorine building has been constructed to the required Uniform Building Code and Uniform Fire Code specifications. However, the possibility of this scenario being initiated by a seismic event can not be completely discarded. This scenario is considered to be extremely unlikely. In the highly unlikely case that this scenario occurs, approximately 50,000-pounds of chlorine would be released. The release of chlorine could occur outdoors or indoors. The release of the chlorine within the chlorine building would result in the chlorine sensors detecting the chlorine and activating the emergency scrubber exhaust fan. This would result in the "sucking up" of chlorine vapors from the building and being routed to the emergency chlorine scrubber. The emergency chlorine scrubber was designed for the purpose of mi tigating the effects of accidental releases of chlorine. Although the emergency chlorine scrubber was installed by the Agency for the specific purpose of mitigating the potential off-site consequences of accidental chlorine releases (such as those described above), the presence of the chlorine scrubber system was not taken into account in evaluating the off-site consequences. Rather, it was assumed that the chlorine released during the catastrophic accident was released outdoors forming a cloud of chlorine vapor. The resulting vapor cloud was assumed to freely migrate off-site. Utilizing the methodology specified by USEPA, the estimated vulnerable zone for this accidental release scenario is approximately 7.0-miles. Figure ES-2A presents a graphical representation of the vulnerable zones for the worst-case release scenario for accidental releases involving chlorine. Also presented in Figure ES-2A are the sensitive receptors located within one-mile of the facility. Table ES-1 provides a listing of sensitive receptors located in close proximity to the facility. Alternative Release Scenarios Alternative release scenarios which are considered to be more likely to occur are those which may result in the release of anywhere from less than one-pound to up to 1000-pounds of chlorine. These scenarios include situations such as delivery of a leaking one-ton container of chlorine to the facility, a pinhole leak in the chlorine transfer piping and a partial or complete failure of the liquid or vapor chlorine transfer lines at various points in the system (either in-doors or out-doors). In order to be conservative in the estimation of the vulnerable zone, it was assumed that 1000-pounds of chlorine was released during an accident involving the complete failure of a liquid transfer line from either the bulk storage tanks or the one ton containers. It was further assumed that the material was released directly outdoors. Since the release can occur out-doors i.e., outside of t he chlorine storage building) the presence of the chlorine scrubber system was not taken into account in evaluating the off-site consequences. Utilizing this assumption is much more conservative in nature and resulted in the estimation of the largest vulnerable zone for these types of accident scenarios. The resulting toxic gas (i.e., chlorine) vapor cloud was assumed to freely migrate off-site. Utilizing the methodology specified by USEPA, the estimated vulnerable zone for these types of scenarios is approximately 1.2 miles. Figure ES-2B presents a graphical representation of the vulnerable zones for the alternative release scenario for accidental releases involving chlorine. Also presented in Figure ES-2B are the sensitive receptors located within one-mile of the facility. Table ES-1 provides a listing of sensitive receptors located in close proximity to the facility. METHANE Worst-Case Release Scenario In this scenario, one of the seven anaerobic digesters on site experiences a c atastrophic failure due to an unknown external event. This scenario would be initiated by some unknown external event (i.e., an airplane, missile or meteorite impacting the digester). This scenario may also be initiated by a seismic event. The digesters have been constructed to the required Uniform Building Code and Uniform Fire Code specifications. This scenario is considered to be extremely unlikely. In the highly unlikely case that this scenario occurs, approximately 20,000-pounds of methane would be released. The release of methane would occur outdoors. The primary hazard associated with methane is explosion and the subsequent overpressure wave. In order to be conservative in the estimation of the vulnerable zone, it was assumed that 20,000 pounds of methane was released and that a vapor cloud containing methane within its explosivity limits was generated and ignited. Utilizing this assumption is much more conservative in nature and resulted in the estimation of the largest vulnera ble zone for these types of accident scenarios. Utilizing the methodology specified by USEPA, the estimated vulnerable zone for these types of scenarios is approximately less than 0.2 miles. Alternative Release Scenarios Alternative release scenarios which are considered to be more likely to occur are those which may result in the release of anywhere from less than one-pound to up to 5,000-pounds of methane. These scenarios include situations such as pinhole leaks or partial or complete failures in the digester gas collection and handling lines or the complete failure of the gas compressors. The primary hazard associated with methane is explosion and the subsequent overpressure wave. In order to be conservative in the estimation of the vulnerable zone, it was assumed that 5,000 pounds of methane was released and that a vapor cloud containing methane within its explosivity limits was generated and ignited. Since the release can occur outside of the energy recovery building, it was as sumed that the material was released directly outdoors. Utilizing this assumption is much more conservative in nature and resulted in the estimation of the largest vulnerable zone for these types of accident scenarios. Utilizing the methodology specified by USEPA, the estimated vulnerable zone for these types of scenarios is approximately less than 0.1 miles. Figure ES-3 presents a graphical representation of the vulnerable zones for the worst-case release scenario and the alternative release scenario for accidental releases involving methane. Also presented in Figure ES-3 are the sensitive receptors located within one mile of the facility. Table ES-I provides a listing of sensitive receptors located in close proximity to the facility. ES 3.0 FIVE YEAR ACCIDENT HISTORY During the five years preceding the submittal of this RMP, the facility has NOT had any releases of regulated substances which have resulted in: 7 Onsite deaths, injuries, or significant property damage; or 7 Known offsite deaths, injuries, property damage, environmental damage, evacuations, or sheltering in place. ES4.0 ACCIDENTAL RELEASE PREVENTION PROGRAM AND CHEMICAL SPECIFIC PREVENTION STEPS The Accidental Release Prevention Program at the Agency consists of a series of programs, procedures and policies designed to minimize the risk of accidental releases involving regulated substances handled at the facility (i.e., the only regulated substances handled at the facility are chlorine and methane contained in digester gas). These programs include design and operating controls such as compliance with specified codes, the health and safety program, numerous standard operating procedures, the equipment inspection and maintenance program (including a mechanical integrity and preventive maintenance program), site security, the management of change program, pre-start-up review, fire prevention/fire protection/hot work permit program, management of- and safety of- contractors, accident/incident inve stigation procedures, emergency response plan, RMP compliance auditing and inspection program, record keeping and a variety of training programs. Details of each of these components of the Agency's Accidental Release Prevention Program are provided in the document entitled Risk Management Plan (RMP), Volume I - Prevention Program. There are several chlorine and methane leak detection and monitoring devices and other protective devices (e.g.., for fire and explosion) placed at strategic locations throughout the facility. Table ES-2 provides a summary listing of these detection and monitoring devices as well as their sensitivities. ES5.0 EMERGENCY RESPONSE The Agency recognizes that emergency planning and emergency response are an integral component of risk management. As such, the Agency currently has emergency action plans and emergency evacuation plans in place. In addition, the Agency has developed a Fire Prevention Plan. These programs work together to mitigate the effects of unp lanned releases or events. However, as a measure to improve safety, the Agency is currently developing a specific response program for emergencies involving chlorine and methane. The Agency is planning to conduct a joint emergency response drill with the San Bernardino County Interagency Hazardous Materials Response Team. This will ensure that key agencies which could be involved in emergency response at the Agency are familiar with the facility operations and hazards and are also familiar with the capabilities of Agency personnel (from an emergency response view point). In addition, these drills will ensure that the existing emergency response plan is evaluated during the drilling process for its functionality, practicality and effectiveness. Based on these drills changes and modifications may be made (as appropriate) to improve response efficiencies. ES6.0 PLANNED CHANGES TO IMPROVE SAFETY A detailed hazard and operability study (i.e., hazards analysis) was performed on ALL opera tions involving chlorine and digester gas (i.e., methane) in order to evaluate the potential for accidental releases. As a result of this hazards analysis a number of recommendations were made to improve the safety of the operations conducted. The recommended actions are summarized in Table ES-3. Table ES-3 also presents the implementation status of the recommended actions. As shown, the Agency has already implemented a number of the recommendations. Table ES-3 also presents the expected date of implementation for those recommendations not yet implemented. ES 7.0 FOR MORE INFORMATION The Agency recognizes that some persons may be interested in obtaining more detailed information regarding risk management prevention program components not discussed herein. Interested parties that have additional questions regarding the Agency's Risk Management Plan, are directed to contact: Mr. Sean R Denman Inland Empire Utilities Agency 9400 Cherry Avenue, Building A Fontana, California 92335 |