Riverside Regional Water Quality Control Plant - Executive Summary |
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Executive Summary Introduction Chemicals are widely used in industry, in the home, in the environment. They are transported on roads, water, and railways. We at the Riverside Regional Water Quality Control Plant (Riverside RWQCP) 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, and we use sulfur dioxide to remove excess chlorine in a final polishing stage of treatment. We re-use digester gas (mostly methane in composition), which is produced during the breakdown of solids, to fuel our boilers. Storing large qualities of chlorine, sulfur dioxide, and digester gas can be a hazard. We take our safety obligations in storing and using these chemicals as seriously as we do 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 safety, and what to do i n event of an emergency. Accidental Release Prevention and Emergency Response Policies The Riverside Public Works Department and Riverside RWQCP accidental release prevention 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. 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 (CCR) Title 19, Division 2, Chapter 4.5. These regulations require facilities storing large quanti ties of certain chemicals like chlorine, sulfur dioxide, and digester gas to prepare a Risk Management Plan (RMP). The Riverside RWQCP has a chlorination system that uses chlorine gas fed from liquid chlorine containers and a dechlorination system that uses sulfur dioxide gas fed from liquid sulfur dioxide containers. During the wastewater treatment process, sludge degradation produces digester gas, which is comprised mainly of methane and is used to fuel process boilers. This document summarizes our existing health and safety programs, our internal response team policies and procedures, and on-going actions that are designed to prevent or minimize impacts of accidental releases of chlorine, sulfur dioxide, or digester gas to the environment. The Riverside RWQCP has prepared an emergency action plan to handle any potential accidental releases. In over 40 years of operation, Riverside RWQCP has an excellent record in preventing accidents from occurring. General Facility and Regula ted Substances Information The Riverside RWQCP, operating since 1948, is located at 5950 Acorn Street in the City of Riverside in Riverside County. The plant, located on a 122-acre property is about 3 miles north of the Van Buren exit of the 91 Freeway. Wastewater from the service area is treated at the Riverside RWQCP and final clean and disinfected water is either discharged into the Santa Ana River or pumped to customers as reclaimed water for landscaping and irrigation uses. This wastewater treatment includes preliminary treatment, primary and secondary treatment, flow equalization, coagulation/filtration, and chlorination and dechlorination before final discharge or reclamation use. The Riverside RWQCP handles wastewater flows up to 40 million gallons per day (MGD), with an average flow of 32 MGD. Riverside RWQCP currently stores chlorine, sulfur dioxide, and digester gas; which are regulated toxic substances under RMP and CalARP. Chlorine is stored in two, 25-ton bulk s teel storage tanks. Sulfur dioxide is stored in two, 25-ton bulk storage tanks. Approximately, 21,000 lbs of digester gas is stored in the headspace of three active digesters, and is used for fuel for the digester system boilers. Federal RMP and CalARP regulations require RMPs for facilities that store more than 2,500 lbs of chlorine, 5,000 lbs of sulfur dioxide, or 10,000 lbs of digester gas (mostly methane). Both liquid chlorine and sulfur dioxide are brought to the plant and transferred to the bulk storage tanks. Either liquid or gaseous chlorine and sulfur dioxide can be withdrawn from the tanks. Facility Safety Systems The chlorine, sulfur dioxide, and digester gas processes at Riverside RWQCP are equipped with numerous safety devices and systems. Some of these safeguards are described below. Entry to the Riverside RWQCP is controlled at Acorn Street by a gate and phone security system. Visitors and contractors must dial the control building and be approved by Riverside R WQCP staff prior to entry into the facility. The Riverside RWQCP is equipped with three wall-mounted chlorine leak detector that during an alarm condition will light a red alarm light within the detector, and activate one alarm signal at the chlorine control panel. The detector will also activate a blue flashing light and audible alarm, and will page the senior operator. The warning level setpoint is at 1 ppm, and the alarm level setpoint is at 3 ppm of chlorine for all leak detectors. A shutoff and pressure-reducing valve is located on the discharge of the chlorine evaporator. The valve prevents liquid chlorine from reaching the gas piping system. An extensive alarm system in the chlorination system is used to detect low vacuum on each chlorinator, high/low water bath temperature on each evaporator, chlorine gas relief high pressure, low weight on bulk storage tanks, expansion chamber high pressure, and other system abnormalities. Pressure relief valves and vacuum regulating c heck valves are located throughout the chlorination system, and are used to prevent a pressure buildup in the gas or liquid pipelines. Three sulfur dioxide leak detectors are provided for the dechlorination system. An alarm light on the face of the sulfur dioxide leak detector flashes when sulfur dioxide gas in excess of 1 ppm is detected. The detector will also activate a blue flashing light and audible alarm, and will page the senior operator. An emergency alarm annunciates at the Operation Interface Station if any of the following are detected: storage area SO2 leak, sulfur dioxide feed room SO2 leak, bulk storage tank expansion chamber high pressure (1 and 2), SO2 gas relief high pressure (each evaporator), or evaporator high water bath temperature (each evaporator). Numerous other warning alarms are included throughout the sulfur dioxide system to ensure worker safety and to protect equipment. The sulfur dioxide system at Riverside RWQCP is equipped with expansion chambe rs in the liquid lines, and vacuum regulating check valves in the gas lines to prevent a pressure buildup in the gas or liquid pipelines. The digester gas system at the Riverside RWQCP is equipped with a safety control system that has a flame-sensing relay and programmer-controlled ignition to start and stop the burner in the event of ignition pilot or flame failure. Automatic spark ignition for the pilot, and automatic restart after a power failure or interruption in fuel supply, is provided. A flame arrester has been included in the digester gas system to cool any flames in the gas line to temperatures below the ignition temperature. A waste gas burner burns any excess digester gas that cannot be used by the boilers to prevent a pressure buildup in the digesters. Offsite Consequence Analysis Results The offsite consequence analysis includes consideration of two release scenarios, identified as "worst case" and "alternative" release scenarios. For toxics, the worst-case scen ario requires that a release of the entire contents of the single largest vessel or pipe of chlorine or sulfur dioxide be evaluated for off-site impacts from either. A separate worst-case analysis is required for digester gas. An alternative release scenario is required for both toxic substances. An alternative release scenario is not required for digester gas, but this process qualifies for Program 1 under CalARP regulations. For the worst-case release scenario analysis, two scenarios were considered: (1) complete de-inventory of a 25-ton capacity chlorine bulk storage tank and (2) complete de-inventory of a 25-ton capacity sulfur dioxide bulk storage tank. Dispersion modeling indicated that chlorine represented the worst case release scenario. Only passive or administrative controls can be considered in the analysis of the worst-case scenario. The scenario used for Riverside RWQCP is the rupture of one 25-ton chlorine bulk storage tank, resulting in a release of 50,000 pounds of chlorine over a 10-minute duration. The release rate will, accordingly, be 5,000 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 estimated using Dense Gas Air Dispersion (DEGADIS 3.0.3) model. 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%). The results of the d ispersion modeling analysis for this worst case release scenario indicate that this scenario has an offsite impact. The worst-case release scenario for the digester gas process involves a vapor cloud explosion of 5,992 lbs of digester gas (2,230 lbs methane), the entire contents of the largest digester at Riverside RWQCP. The flammable endpoint use was an overpressure of 1 pound per square inch (psi). The results of the evaluation indicate that the worst case release scenario does not have offsite impacts. For this reason, the digester gas is a Program 1 process under federal RMP and CalARP regulations. The alternative release scenario is more likely to could occur compared to the worst-case release scenario. Based on the process hazard analysis performed for both the chlorine and sulfur dioxide systems, two alternative release scenarios were selected. Unlike the worst case release scenario, active controls can be considered to minimize the leak or impacts. Active controls con sist of mechanical, electrical, or human input. The scenario used for both chlorine and sulfur dioxide was a rupture of a pipe leading from the bulk tank to the evaporator. The sulfur dioxide tanks, evaporators, and associated piping are all in a building; and the building mitigation was considered. Also considered are reductions in the leak due to safety excess flow valves that operate to reduce the liquid chlorine or sulfur dioxide leaks. The calculated sulfur dioxide release rate is 4.16 lb/min, after incorporation of the building mitigation factor of 0.55 because the sulfur dioxide piping system is enclosed within the chemical building. The release rate from the 1/16-inch leak for chlorine is 10.11 lb/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 3.0 meters per second, average air temperature of 63 degrees F, and average humidity of 64%. The results of the dispersion modeling analysis for both alternative release scenarios indicate that these scenarios have an offsite impact. Finally, no chlorine or sulfur dioxide releases that could have cause safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at Riverside RWQCP during the last five 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 The Riverside RWQCP is in compliance with Federal and State Process Safety Management (PSM) requirements. Chemical-specific prevention steps include availability of self-contained escape breathing apparatus, which are on hand and available to be worn by the operators during connection and disconnection of the chlorine and sulfur dioxide supplies, awareness of the hazardous and toxic properties of chlorine and sulfur dioxide, and the presence of chlorine and sulfur dioxide detectors and alarms. The Riverside RWQCP 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 program 7 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 Compr ehensive 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, sulfur dioxide, and digester gas background information, MSDS sheets, and chlorine, sulfur dioxide, and digester gas reaction chemistry. Equipment safety information has been compiled on the chlorine and sulfur dioxide processes, and 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. This information is contained in Section 2 of the Process Safety Managem ent Plan. We also have scheduled reviews of our risk management program and process safety management plan to update safety information if there is a major change that makes existing information inaccurate. Process Hazard Analysis In March 1999 a detailed process hazard analysis (PHA) was conducted with plant staff, engineering, and administrative staff for the regulated processes. The team consisted of process operating and maintenance experts and process design engineers. The PHA technique used was the "What-If" investigation method, per acceptable approach guidance from EPA. The PHA was lead by a knowledgeable person on the type of process being reviewed. This review will be updated again within a five-year 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, and recommendations were provided to Riverside RWQCP for their evaluations and implementation. Operating Procedures Riverside RWQCP maintains up-to-date, accurate, written operating procedures that give clear instructions for the chlorine, sulfur dioxide and digester gas processes. Riverside RWQCP 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, sulfur dioxide and digester gas systems. Procedures include startup, shutdown, and normal, alternate, and emergency operation. Also included are maintenance and troubleshooting procedures, including consequences of deviation and the steps to avoid deviations. Riverside RWQCP will update procedures whenever a change occurs that alters the steps needed to operate safely. Operating procedu res 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 Riverside RWQCP employee presently involved in operating or maintaining the chlorine, sulfur dioxide and digester gas processes is trained in an overview of the process and detailed, applicable operating and maintenance procedures. This training helps employeesunderstand the nature and cause of problems arising from operations involving chlorine, sulfur dioxide, and digester gas, and increase employee awareness of their hazards. Riverside RWQCP'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 mater ial 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, and an on-going employee training record. Contractors The Riverside RWQCP 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 and sulfur dioxide processes. Contractors are properly informed of the hazards, access limitations to these process areas, and emergency response procedures, and must be prepared to safely complete the work. The Riverside RWQCP sets minimum contractor safety performance requirements to do work in process areas, holds contractor safety briefings before allowing them near or in the process area; controls access to the process areas, and evaluates the contractor's performance. Pre-Startup Safety Review and Mechan ical Integrity Program The Riverside RWQCP ensures that a pre-startup safety review is completed for any new regulated process at the plant, or for significant modifications to an existing covered process that requires a change in the process safety information. Riverside RWQCP maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public, or the environment. Riverside RWQCP believes that this program is the primary line of defense against a release. Maintenance staff address equipment testing and inspection, preventative maintenance schedules, and personnel training of these procedures. Riverside RWQCP's 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 performi ng 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; and 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 The Riverside RWQCP requires employees and contractors to employ safe work practices when performing "hot work" in, on, or around the regulated processes. Riverside RWQCP uses a comprehensive permitting and training program to ensure hot work is conducted safely. Riverside RWQCP provides a system and approach to maintain and implement any management of changes or modifications to equipment, procedures, chemicals, and processing conditions. This system allows Riverside RWQCP employees to identify and review safety h azards or provide addition safety, process, or chemical information to existing data before the propose 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. Riverside RWQCP assembles an audit team that includes personnel knowledgeable in the Risk Management Program rule and in the regulatory process. 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 implemented. Incident Investigation The Riverside RWQCP investigates all incidents that could reasonably have resulted in a serious injury to personnel, the public, or th e environment so that similar accidents can be prevented. Riverside RWQCP 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 appropriate staff and is added to or used to revise operating and maintenance procedures. Information from audits and any resulting changes in operating procedures are 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 reportable accidental releases that resulted in onsite or offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage have occurred at the Riverside RWQCP in the last five yea rs. Emergency Response Program Summary Riverside RWQCP has established a written emergency action program that is followed by the employees to help safely control accidental releases of hazardous substances. This program has been coordinated (reviewed) by the City of Riverside Fire Department, which is a member of the Local Emergency Response Planning Committee (LEPC). This program includes an emergency action and notification plan. Emergency operation and action procedures are also reviewed once per year. Planned Changes to Improve Safety The Riverside RWQCP has scheduled feasiblity studies to investigate alternative disinfection processes such as ultraviolet oxidation, and alternate, less hazardous chemicals such as sodium hypochlorite or sodium bisulfate. |