Rialto Wastewater Treatment 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 Rialto Wastewater Treatment Plant (Rialto WTP) use chemicals, too. For example, we use chlorine to disinfect our water to provide safe water discharges to the environment and we use sulfur dioxide to remove excess chlorine in a final polishing stage of treatment. Storing large qualities of chlorine and sulfur dioxide can be a hazard. We take our safety obligations in storing and using these chemicals as seriously as we take protecting water quality through the wastewater treatment. 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 in event of an emergency. Accidental Release Prevention and Emergency Response Policies The City of Rialto Department of Public Works and Rialto WTP accidental release prevention policy involve s a unified approach that integrates proven technology, staff training on operation and maintenance practices, and 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 EPA 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 quantities of certain chemicals like chlorine and sulfur dioxide to prepare a Risk Management Plan (RMP). The Rialto WTP has a chlorination system that uses chlorine gas fed from liquid chlorine containers and a dechlorination system that use s sulfur dioxide gas fed from liquid sulfur dioxide containers. 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 or sulfur dioxide to the environment. The Rialto WTP has prepared an emergency action plan to handle any potential accidental. In over 40 years of operation, the Rialto WTP has an excellent record in preventing accidents from occurring. General Facility and Regulated Substances Information The Rialto WTP, operating since 1956, is located at 501 East Santa Ana Avenue in the City of Bloomington in San Bernardino County, California. The plant is located approximately one mile south of the San Bernardino Freeway and one-half mile east of Riverside Avenue. Wastewater from the City of Rialto Department of Public Works service area is treated at the Rialto WTP and highly treated, disinfected water produce d is discharged into the Rialto Channel. This wastewater treatment includes preliminary treatment, flow equalization, primary and secondary treatment, coagulation/filtration, and chlorination and dechlorination before final discharge or reclamation use. The Rialto WTP handles wastewater flows up to 8 million gallons per day (MGD), with an average flow of between 5.8 to 6.4 MGD. The facility currently stores chlorine and sulfur dioxide; both regulated toxic substances under RMP and CalARP regulations. Chlorine is stored in a 7,000 gallon steel bulk storage tank, which holds a maximum of 34 tons. Sulfur dioxide is stored in a 7,000 gallon steel bulk storage tank, which holds a maximum of 31.5 tons. Both liquid chlorine and sulfur dioxide are brought to the plant by truck and transferred to the bulk storage tanks. Either liquid or gaseous chlorine and sulfur dioxide can be withdrawn from the tanks. Facilities storing more than 2,500 lbs of chlorine and 5,000 lbs of sulfur dioxide are required to prepare an RMP in accordance with federal RMP and CalARP regulations. Facility Safety Systems Chlorine and sulfur dioxide leak detectors monitor continuously for leaks in the bulk storage areas and in the chlorination and sulfonator rooms. The leak detectors are self-contained, electrically- operated devices designed to detect 0.5 ppm by volume of chlorine or sulfur dioxide in the air. If a leak occurs, a level of 0.5 ppm will turn on a red warning light on top of the building and will sound an audible alarm. The detector also will send a signal to the central computer system that activates an alarm on the annunciator board in the control building and also lights a panel alarm on the detector unit itself in the equipment room. Other alarms include excess flow alarms and evaporator malfunction alarms. These alarms are annunciated at the chlorine and sulfur dioxide central and local control panels. Expansion chambers, rupture discs, and pressure relief valves are located throughout the chlorine and sulfur dioxide processes to protect against excess pressure. All processes related factory-set pressure relief valves are set to protect the safety of workers and the integrity of the equipment. Both the chlorine and sulfur dioxide storage tanks are equipped with a safety relief valve and excess flow valves for liquid. The safety relief device in the center of the tank manway dome is equivalent to a pressure relief valve in the event excess pressure builds up in the storage tank. The excess flow valves are ball-check type valves located directly beneath the angle valves for both liquid and gas chlorine or sulfur dioxide. These excess flow valves are designed to close automatically against the flow of liquid or gaseous chemicals if an angle valve is broken off or a major piping leak occurs downstream of the storage tank. The controls for the chlorine and sulfur dioxide evaporators are equipped with two protection devices. One device monitors the level of the water in the jacket and issues an alarm should the level reach a dangerously high or low level. The other alarm will engage should the temperature of the water be too high or low for proper evaporation of the sulfur dioxide gas. Another alarm on the evaporator discharge piping monitors gas pressure and is equipped with rupture disc and pressure switch to alert operations personnel of a problem either with the evaporator or the downstream valving or equipment. Emergency showers and eye wash stations are provided at the chemical building. Emergency air packs are available near the chemical process rooms, and fire extinguishers are available at the Chemical Feed Room. The single road entry to Rialto WTP is controlled at Santa Ana Avenue by a gate. The chemical building remains locked and only a limited number of Rialto WTP staff have keys. The plant is staffed during the day, year round, and alarms notify on-call staff during off-hours of any problems or situati ons that require followup investigation. Offsite Consequence Analysis Results The offsite consequence analysis includes consideration of two release scenarios, identified as "worst case" and "alternative" release scenarios. The worst-case scenario requires that that single largest vessel or pipe be evaluated for off-site impacts from either chlorine or sulfur dioxide. The rupture of both the chlorine tank and a sulfur dioxide tank were modeled for the worst-case release scenario, but the resulting affected area was greater under the chlorine release scenario. Only passive or administrative controls are allowed under this scenario to reduce off-site impacts. An alternative release scenario is required for both substances. The worst case scenario for Rialto WTP is the rupture of the chlorine bulk storage tank, resulting in a release of 68,000 pounds of chlorine over a 10-minute duration. Since the chlorine storage tank is located inside a building, EPA's building mitigation factors were considered for estimating the release rates for performing air dispersion modeling for the worst-case release scenario. The release rate of chlorine, considering the EPA mitigation factor will, accordingly, be 3,740 pounds per minute (lbs./min). In practice this type of total release of a bulk tank would be unlikely to 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 the 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 (115 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, but still is highly unlikely. In accordance with regulations guiding this report, alternative release scenarios were evaluated for both chlorine and sulfur dioxide. Unlike the worst-case release scenario, active controls can be considered in analyzing the alternative release scenario. Active controls consist of mechanical, electrical, or human input. The scenarios selected for the Rialto WTP chlorination and dechlorination systems involve the release of chlorine and sulfur dioxide vapor from a leak in a flange or valve, resulting from an operator error during tank isolation for hydrostatic testing. The leak is assumed to be 1/16-inch in diameter for both sulfur dioxide and chlorine. The chemical process buildings contain chlorine and sulfur dioxide leak detection equipment, and it is assumed that the duration of the leak is approximately ten minutes. Under this scenario, the amount of chlorine and sulfur dioxide released were calculated to be 0.25 and 0.15 lb/min, respectively. 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 63 degrees F, and average humidity of 51 percent. The results of the dispersion modeling analysis for the chlorine and sulfur dioxide alternative release scenarios indicate that these scenarios have an offsite, but very limited, impact. Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps Rialto WTP is in compliance with Federal and State Process Safety Management ( PSM) requirements. Chemical-specific prevention steps include availability of self-contained escape breathing apparatus; awareness of the hazardous and toxic properties of chlorine and sulfur dioxide; and the presence of chlorine and sulfur dioxide detectors and alarms. Rialto WTP 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 investi gation, 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 and sulfur dioxide background information, MSDS sheets, and chlorine and sulfur dioxide 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 faci lity. 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 May 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 specialists and process design engineers. The PHA technique used was the "What-If" study, 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 5-year period or whenever there is major change in the process. A list of actions to resolve any found significant findings from the May 1999 analysis 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 Rialto WTP for their evaluations and implementation. Operating Procedures Rialto WTP maintains up-to-date, accurate, written operating procedures that give clear instructions for the chlorine and sulfur dioxide processes. Rialto WTP 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 and sulfur dioxide 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 correct deviations. Rialto WTP 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 p rocess equipment coming on line or a changed process starting back up. Operations and Maintenance Training Program Each Rialto WTP employee presently involved in operating or maintaining the chlorine and sulfur dioxide processes is trained in an overview of the process and detailed, applicable operating and maintenance procedures. The training helps employees understand the nature and cause of problems arising from operations involving chlorine and sulfur dioxide onsite, and increases employee awareness of their hazards. Rialto WTP'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, and an on-going employee training record. Contractors Rialto WTP 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. Rialto WTP sets minimum contractor safety performance requirements for 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 Mechanical Integrity Program Rialto WTP ensures that a pre-startup safety review is completed for any ne w regulated process at the plant, or for significant modifications to an existing covered process that requires a change in the process safety information. Rialto WTP maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public, or the environment. Rialto WTP 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. Rialto WTP'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 performing inspections and tests on process equipment at specified intervals 7 Training of maintenance personnel in procedures for sa fe 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 Rialto WTP requires employees and contractors to employ safe work practices when performing "hot work" in, on, or around the regulated processes. Rialto WTP uses a comprehensive permitting and training program to ensure hot work is conducted safely. Rialto WTP provides a system to manage changes or modifications to equipment, procedures, chemicals, and processing conditions. This system allows Rialto WTP employees to identify and review safety hazards or provide additional safety, process, or chemical information to existing data before the proposed change would either comprise system safety or need training to be completed. Internal Complianc e Audits Internal compliance audits will be conducted every 3 years to verify compliance with the programs and procedures contained in the RMP. Rialto WTP will assemble an audit team that includes personnel knowledgeable in the Risk Management Program rule and in the regulatory process. This team will evaluate 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 Rialto WTP 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. Rialto WTP trains employees to identify and report any incident that requires investigation. An investigation team is assembled and the inves tigation 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 On March 5, 1999 a routine delivery of sulfur dioxide was being offloaded to the pressurized container. At approximately 8:30AM the driver notified the staff of a leak within the SO2 storage building. The offloading procedures were stopped and emergency procedures were implemented. The fire department was notified of a confirmed leak in the SO2 bulk storage room. All employees were accounted for and were prepared to evacuate. At approximately 9AM there was a report of a sulfur odor in the administration building, and the entire facility, including the contractors and a neighboring business, was evacuated. County HazMat and Rialto Fire Department responded to the incident and stabilized the area. The area was declared clear at approximately 12:00 noon. No injuries, deaths, or sheltering in place occurred during the incident. Approximately 50 people were evacuated to prevent possible exposure. No property was damaged by the release, which was estimated to be less than one pound of sulfur dioxide gas. Emergency Response Program Summary Rialto WTP 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 San Bernardino County 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 safety of the chlorine and sulfur dioxide processes was reviewed in May 1999 in the process hazard analysis. Based on these reviews, additional changes or recommendations were identified to improve the safety of the chlorination and dechlorination systems. The recommendations include assessing the preventive maintenance program of the chlorine and sulfur dioxide supplier, reviewing and updating the chemical delivery procedures, and performing a seismic assessment to evaluate the structural integrity of the processes. |