Sunnyvale Water Pollution Control Plant - Executive Summary |
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EXECUTIVE SUMMARY Introduction: Chemicals are widely used in industry, in the home, and in the environment. They are transported on roads, water, and railways. The City of Sunnyvale Water Pollution Control Plant (SWPCP) uses chemicals such as chlorine and sulfur dioxide to disinfect treated wastewater to provide safe water for discharge to the environment and for recycled water uses such as landscaping and irrigation. Storing large qualities of these chemicals can be a hazard. We take our safety obligations in storing and using hazardous chemicals as seriously as we take providing reliable wastewater treatment. This document describes what could happen if there were to be an accidental chemical release, the steps we take every day to ensure a safely operated plant, and how we respond to an emergency. To date, we have had an excellent record in preventing accidental releases. Please feel free to contact Lorrie Gervin, Environmental Division Manager, at (408) 730-7260 if you have any que stions. Accidental Release Prevention and Response Policies The SWPCP has already implemented programs to comply with several other accidental release prevention regulations including California's OSHA Process Safety Management (PSM) program and California's Risk Management and Prevention Program (RMPP) because of use and storage of chlorine and sulfur dioxide. The California RMPP law was repealed in January 1997 and replaced by the CalARP regulation. It is the policy of the SWPCP to develop, maintain, and implement this RMP/PSM Plan. This RMP/PSM plan complies with the U.S. Environmental Protection Agency's (EPA's) Risk Management Program (RMP), under Section 112 (r) of the Clean Air Act (CAA) Amendments of 1990, 40 Code of Federal Regulations (CFR) Part 68, the California Accidental Release Prevention (CalARP) Program under California Code of Regulations (CCR) Title 19, Division 2, Chapter 4.5, and the Process Safety Management Program under CCR Title 8, Division 1, Chapter 4, Secti on 5189 and 29 CFR 1910.119. General Facility and Regulated Substances Information The SWPCP is located at 1444 Borregas Avenue in Sunnyvale, near the southern tip of the San Francisco Bay. SWPCP treats wastewater from the City of Sunnyvale, a small section of Cupertino, and a portion of Moffett Field Naval Air Station, located in Sunnyvale. The plant has a capacity of 29.5 million gallons per day; average flow is 18 million gallons per day. Plant processes include preliminary treatment to remove large solids and grit, primary sedimentation to remove settleable solids, oxidation ponds as secondary treatment, biological treatment to convert ammonia to nitrates, flocculation and coagulation for algae removal, filtration to remove suspended solids, disinfection to inactivate disease-causing organisms and dechlorination. The SWPCP is a 24-hour per day/7-day per week operation. A Senior Operator is always on duty at the facility and will initiate established emergency response procedure s in the event of an accidental release or other emergency situation. The facility currently stores chlorine, sulfur dioxide, and digester gas; all regulated toxic substances under RMP and CalARP. Chlorine and sulfur dioxide are stored in 1-ton containers and exceed the RMP and CalARP threshold quantities. Digester gas is stored in four digester domes and associated process piping. Calculations maintained at the SWPCP in the RMP files demonstrate that the amount of digester gas stored does not exceed the CalARP rule threshold. Based on the April 2000, EPA Fact Sheet on Section 112(r), methane used as fuel at a wastewater treatement plant is no longer covered by the Risk Management Program by EPA. Chlorine is added to the wastewater to kill disease-causing organisms. Sulfur dioxide is used after disinfection is completed to convert chlorine to chloride, which is harmless to fish and other aquatic life in the receiving water. Chlorine and sulfur dioxide are both used in the disinfectio n process and are stored, transported, and applied in physically separate, but similar systems. Chlorine and sulfur dioxide containers are delivered to the site on flat-bed trucks. Receipt of container deliveries is performed by SWPCP personnel. All chlorine and sulfur dioxide containers are immediately unloaded and placed inside the storage buildings where they are safety-secured. The containers are never left outside or unattended. The chlorine and sulfur dioxide systems include several safety features and are in full compliance with County of Santa Clara's (County) stringent Toxic Gas Ordinance (TGO). Safety provisions include: ? Secondary containment-containers and all process equipment are located within the building and the building is under negative pressure under normal and emergency ventilation conditions. ? 3,000 cubic feet per minute (cfm) packed-bed scrubber to treat exhausted air if a release of chlorine or sulfur dioxide occurs. ? Louvers automatically close upon detect ion of a leak and the room space is exhausted to the packed-bed scrubber. ? Sulfur dioxide and chlorine storage and use rooms are equipped with smoke detectors, gas leak detectors, and seismic detectors and manually activated panic buttons at the chlorine and sulfur dioxide facility exits. - Gas leak detectors in each chlorine and sulfur dioxide storage and use room are inter-connected to the PLC system with a tiered action system that includes automatic shutdown of the building ventilation systems, activation of the scrubber system, activation of chlorine and sulfur dioxide shutoff valves, and activation of the the audible and visual alarm system (plant siren) if triggered. Automated dampers are used to direct air flow to the scrubber from the appropriate containment area. A sensor at the scrubber stack exit will provide automatic shutdown of the scrubber in the event of a detected release above the trigger level. - Seismic detectors will cause liquid chlorine and sulfur dioxide sup ply valves to close and annunciate alarms to indicate the shutoff valves have closed in the event of significant seismic activity. - Manually-activated panic buttons will cause the chlorine and sulfur dioxide supply valves to close and annunciate alarms to indicate the shutoff valves have closed. ? Ancillary chlorine and sulfur dioxide process equipment used for handling chlorine and sulfur dioxide containers includes the following safety features: - Containers are equipped with fusible plugs for pressure relief and steel protective housings for the valve area. - All valves and fittings used on the chlorine system are certified for chlorine use. - The header system is equipped with a frangible disk, shutoff valves, and a high pressure switch. - The chlorine and sulfur dioxide evaporators are thermostatically controlled. - The chlorine system pressure relief valve is vented through the scrubber. ? The facility maintains a Chlorine Institute Emergency "B" Kit for use in responding to a leak from the ton containers and self-contained breathing apparatus (SCBAs) for use during equipment change out and emergency response situations. ? The SWPCP is enclosed by a fence with controlled access. System alarms are monitored at the computer control center staffed with operators 24 hours per day. Offsite Consequence Analysis Results The SWPCP has had an excellent safety record. However, we have evaluated scenarios that would result in offsite consequences as a way to communicate process risks to the public, to communicate response issues to the County emergency response organization, and as a tool in evaluating plant safety systems. The offsite consequence analysis for chlorine and sulfur dioxide included a worst case release scenario as defined by the RMP and CalARP regulations, and an alternative release scenario. The worst case scenario for chlorine and sulfur dioxide releases as defined by the RMP and CalARP regulations, consists of releasing the entire contents of one chlorine or sulfur dioxide container in 10 minutes. This scenario is extremely unlikely. This scenario assumes that the incident occurs after the containers have been delivered and are in the chlorine storage building because containers at this facility are not stored outside. An EPA-developed air dispersion model called RMP*Comp was used to estimate the distance to a point where the concentration would become diluted to a level no longer considered hazardous to the public. The calculated distance for this worst-case scenario was 0.5 miles, which takes into account that the chlorine or sulfur dioxide use and storage is within a building in the event of a release. This distance, as calculated by RMP*Comp, should be considered conservative, as the model takes into account worst-case weather conditions. In addition, this scenario does not take into account SWPCP's existing safety and prevention programs or the scrubber and detection and alarm systems. Using census data from LandVi ew? III, the estimated population within the SWPCP vulnerability zone is 25 persons. It should be recognized that this result is based on an unrealistic scenario, using a conservative model and weather conditions. A second, alternative release, scenario was identified based on the process hazard analysis (PHA) as the occurrence of 0.1-inch diameter leak in a valve packing on either a chlorine or sulfur dioxide storage container. The SWPCP estimates that this type of leak could be secured within approximately 20 minutes. This scenario is less improbable than the worst-case release scenario. It takes into account that SWPCP's extensive safety and release prevention systems will help to mitigate the impacts of such a release. The relatively small quantity of chlorine or sulfur dioxide gas that is estimated to be released through this hole would be contained by the storage building. Also, released gas would be treated by the scrubber system. Thus, it was determined that there is minimal offsite impact associated with this alternative release scenario for either chlorine or sulfur dioxide. SWPCP has developed and implemented the systems in its RMP/PSM program to prevent or mitigate such releases. Five-Year Accident History There have been no releases of chlorine or sulfur dioxide in the last five years that have resulted in deaths, injuries, or significant property damage onsite or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage. Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps The SWPCP chlorine and sulfur dioxide systems are required to be managed under stringent release prevention and emergency response programs by both the OSHA Process Safety Management (PSM) Program regulations and the RMP/CalARP regulations because of the quantities stored and potential for offsite impacts. The SWPCP RMP/PSM Plan summarized herein addresses the chlorine and sulfur dioxide proc esses. SWPCP's RMP/PSM Plan is based on the following key elements: ? Management system and levels of responsibilities and team member roles; ? Comprehensive process safety information that is readily available to staff, emergency responders, and contractors; ? A computerized preventive maintenance and work order tracking program; ? A completed process hazard analysis of equipment and procedures with operation and maintenance staff participation and review; ? Use of state-of-the-art process and safety equipment; ? Use of accurate and effective operating procedures with participation of operations and maintenance staff for review and revision as required; ? High level of training of operators and maintenance staff and on-going refresher training; and ? Incident investigation, inspection, and auditing programs using qualified staff. Process and Chemical Safety Information Comprehensive chemical data have been assembled to include regulatory reporting and action thresholds, health h azards, and chemical exposure limitations, as well as detailed physical properties of each regulated substance. This information was compiled from numerous sources prior to conducting the process hazard analysis and 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, including 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. SWPCP also has procedures in place to update safety information if there is a major change that makes existing information inaccurate. Process Hazard Analysis A detailed initial PHA was conducted with plant staff, engineering, and administrative staff of the chlorine and sulfur dioxide processes in December 1993. A revalidation of that PHA was conducted in December 1999. The PHA re validation team consisted of process operating and maintenance and inspection staff. The PHA technique used was the "Hazard and Operability" (HAZOP) method and "What if" methods as per acceptable approach guidance from EPA. The PHA revalidation was led by a person who was knowledgeable about the type of process being reviewed. A list of actions and suggested improvments from the hazard review findings of the December 1999 PHA revalidation was prepared and received by the SWPCP on January 25, 2000. SWPCP staff have already implemented the majority of the suggested operational improvements identified in this report. The completion date for remaining suggested operational improvements is 1/ 1/ 2001. A seismic evaluation of the chlorine and sulfur dioxide storage facilities and processes was conducted at the same time as the initial PHA (December 1993), prior to construction of building upgrades to comply with the 1994 County Toxic Gas Ordinance. The building upgrades included modif ications to address issues identified during the initial seismic evaluation. The building modifications were constructed in accordance with 1994 Uniform Building Code requirements. A walk-through to review and evaluate these modifications for compliance to current RMP/CalARP seismic requirements was done in December 1999. A suggested list of actions and improvements was prepared as a result of the seismic evaluation. The seismic stability improvements identified in the January 25, 2000 Seismic Structural Report will be completed by 7/1/2001. Operating Procedures The SWPCP maintains up-to-date, accurate, written operating procedures that include clear instructions for operation of the chlorine and sulfur dioxide processes. Operating procedures are incorporated into operation and maintenance training programs. Step-by-step written operating instructions have been developed for the chlorine and sulfur dioxide systems that include procedures for process startup, shutdown, and normal, alt ernate, and emergency operation. The SWPCP SOP Committee annually reviews and updates procedures as needed. Also, procedures are updated whenever a change occurs that alters the steps needed to operate safely. Operating procedures are developed and put in place prior to any new process equipment coming on line or a changed process starting back up. Operations and Maintenance Training Program Each SWPCP 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 SWPCP training program provides information to help employees understand the nature and cause of problems arising from operations involving chlorine and sulfur dioxide onsite, and increases awareness of employees with respect to process hazards. The SWPCP training program includes both initial and refresher training that covers (1) a general overview of the processes, (2) the propert ies and hazards of chlorine and sulfur dioxide (3) SCBA use and qualifications, and (4) a detailed review of process operating procedures and safe work practices. Training documentation maintained by SWPCP includes: the date of most recent review or revision to the training program; type of training provided; and the type of competency testing used to ensure that staff understand the training. Contractors The SWPCP has developed and implemented procedures and policies to ensure that only contractors with good safety programs are selected to perform work on and around the chlorine and sulfur dioxide processes. Contractors are informed of process hazards, process area access limitations, and emergency response procedures so that they may safely complete their work. SWPCP sets minimum contractor safety performance requirements to perform work on or around the chlorine and sulfur dioxide process areas and equipment, holds contractor safety briefings before allowing contractor s near or in the process areas, controls access to process areas, and evaluates contractor performance. Mechanical Integrity Program The SWPCP maintains the mechanical integrity of all facility equipment, including covered process equipment, to help prevent equipment failures that could potentially endanger workers, the public, or the environment. We believe that this program is the primary line of defense against a release and addresses equipment testing and inspection, preventive maintenance schedules, and personnel training. The SWPCP mechanical integrity program includes the following: ? Procedures for maintaining mechanical integrity through inspection and testing of process equipment based on instructions of manufacturers, equipment vendors, industry codes, and prior operating experience; ? Implementation of the written procedures in performing inspections and tests on process equipment at specified intervals; ? Training of maintenance personnel in procedures for safe work pract ices such as lockout/tagout, line or equipment opening, and avoidance and correction of unsafe conditions; and ? 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 SWPCP requires employees and contractors to employ safe work practices when performing "hot work" in, on, or around the chlorine or sulfur dioxide processes, as well as other areas of the facility where flammable materials may be used or stored. Hot work permits (cutting/welding permits) are required by the SWPCP for work undertaken outside of a designated welding booth and permits are issued by a department supervisor. Management of Change and Pre-startup Safety Reviews The SWPCP provides a system and approach to maintain and implement changes or modifications to equipment, procedures, chemicals, and processing conditions. This system allows employees to identify and review saf ety hazards, provide additional safety, process, or chemical information to existing data, evaluate the proposed change to confirm that it would not compromise system safety, and establish training requirements before implementation. The SWPCP ensures that a pre-startup safety review is completed for any new covered-by-the-rules process at the plant, or for significant modifications to an existing covered process that requires a change in the process safety information. Internal Compliance Audits Safety audits are conducted at least annually. Internal compliance audits to verify compliance with RMP/PSM program data, systems, and procedures will be scheduled at least every three years. The SWPCP assembles an audit team that includes personnel knowledgeable about the RMP/PSM Plan and about the process. This team evaluates whether the RMP/PSM Plan and its implementation satisfies the requirements of the RMP/CalARP and PSM requirements and whether the RMP/PSM Plan is sufficient to help ensure safe operation of the chlorine and sulfur dioxide processes. The results of the audit are documented, recommendations are resolved, and appropriate enhancements to the RMP/PSM Plan are implemented. Incident Investigation In addition to its routine industrial accident investigation program, the SWPCP investigates all incidents involving chlorine or sulfur dioxide that caused or could reasonably have resulted in a serious injury to personnel, the public, or the environment so that similar accidents can be prevented. The SWPCP trains employees to identify and report any incident that requires investigation. An investigation team is assembled to investigate covered process incidents. Results of the investigation are documented, recommendations are resolved, and appropriate process enhancements are implemented. Incident investigation report findings are reviewed by affected staff, added or used to revise operating and maintenance procedures, and passed on to the Maintenance Manage r and Supervisors for inclusion in existing training programs, if warranted, to prevent a future event. Emergency Response Program Summary The SWPCP has established a written emergency response program for employees to help safely respond to accidental releases of hazardous substances. This program has been coordinated with the City of Sunnyvale and the County emergency response agencies. The program includes emergency response procedures and an evacuation plan specific to the chlorine and sulfur dioxide processes. Chlorine area operators are trained as first responders. Emergency response drills and drill evaluations are conducted every 6 months. Emergency operation and response procedures are also reviewed at that time. Planned Changes to Improve Safety The Seismic Evaluation Report of January 2000 recommended the following mitigating measures: -Upgrade of some pipe connections to the wall to allow limited displacements; -Modification of some pipes connecting the evaporators and c hlorinators to allow differential displacement, and; -Modification of the emergency scrubber ventilation duct to provide flexible connections at the wall penetrations and along the duct between the Chlorine and Sulfur dioxide storage buildings. These structural modifications and upgrades are scheduled for completion by July 1, 2001. A list of action items based on the chlorine and sulfur dioxide PHA was developed is being implemented. It is anticipated that these action items will be completed by January 1, 2001. A list of actions and suggested improvements to the facility operations was prepared from the hazard review findings of the December 1999 PHA revalidation. SWPCP staff have been and are continuing to address each of the findings listed. It is anticipated that all actions and improvements based on the PHA revalidation findings will be completed by January 1, 2001. Documentation of the closeout of these actions will be maintained by the Maintenance Manager and kept in the RMP facility file. |