Grass Valley Wastewater Treatment Plant - Executive Summary |
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1. Executive Summary 1.1 Introduction Chemicals are widely used in industry, in the home, in the environment. They are transported on roads, water, and railways. We at the Grass Valley Wastewater Treatment Plant (Grass Valley WTP) use chemicals, too. For example, we use chlorine to disinfect our treated wastewater and provide a safe environment to our community. Storing large qualities of chlorine 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 a safety, and what to do in event of an emergency. 1.2 Accidental Release Prevention and Emergency Response Policies The Lake Arrowhead Community Services District and the Grass Valley WTP accidental release prevention policy involves a unified approach that integrates proven technology, staff tr aining 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 (CCF) Title 19, Division 2, Chapter 4.5. The Grass Valley WTP has a chlorination system that uses chlorine gas fed from 1-ton chlorine containers. This document summarizes our existing health and safety programs, our internal response policies and procedures, and on-going actions that are designed to prevent or minimize impacts of accidental releases of chlorine to the environment. The Grass V alley WTP has prepared an emergency response plan to handle any potential accidental releases. To date, we have had an excellent record in preventing accidents from occurring. 1.3 General Facility and Regulated Substances Information The Grass Valley Wastewater Treatment Plant is a wastewater treatment and reclamation plant located at 27000 Pilot Rock Road near Lake Arrowhead, California. The plant was first constructed in 1988. The Grass Valley WTP provides sanitation services to customers of the Lake Arrowhead Community Services District. The wastewater processes at the Grass Valley WTP include both solids and liquid handling and they are: 7 Preliminary treatment 7 Primary treatment 7 Secondary treatment 7 Sludge Thickening 7 Sludge Dewatering 7 Chlorination The facility currently stores chlorine, a regulated toxic substance under RMP and CalARP regulations. Chlorine is stored in 1-ton cylindrical storage containers. This chlorine storage exceeds the listed threshold quan tities in the RMP and CalARP regulations. Liquid chlorine is brought to the plant in containers and stored until use in a building. To disinfected treated wastewater, gaseous chlorine is withdrawn from the containers and injected into the plant effluent. The chlorine process is checked once during every 8-hour shift (twice a day) as part of the normal rounds at this facility. Chlorine leak detectors monitor continuously for leaks in the in the chlorine equipment room (chlorinator room) and one in the chlorine storage room. The leak detectors are set to alarm at 1 ppm. At 1 ppm, an alarm is activated in the control room, and alarm and flashing lights are activated inside and outside the chlorination building. In addition to the audible and visual alarms to alert operators near the chlorine building, the central computer sends an alarm via the phone system to dial out an alarm. All ton chlorine containers are equipped with fusible metal type safety relief devices, called fusib le 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. Other alarms include feed and pressure alarms. These alarms are annunciated at the chlorine central and local control panels. All processes related factory-set pressure relief valves are set to protect the safety of workers and the integrity of the equipment. Emergency showers and eye wash stations are provided at the chlorine building. The main control building has a 5-minute emergency air pack available. Fire extinguishers are available at both the chlorine storage room and the chlorinator room. Entry to Grass Valley WTP is controlled by a fence and gate. Visitors and contractors must be approved by Grass Valley WTP staff prior to entry into the facility. The chemical building remains l ocked and only a limited number of Grass Valley WTP employees have keys. 1.4 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 the entire contents of the single largest vessel or pipe containing chlorine be evaluated for off-site impacts. The alternative release scenario represents a more realistic, but still unlikely, release scenario. Only passive or administrative controls are allowed to be considered under the worst-case release scenario in analyzing offsite impacts. The worst case scenario for Grass Valley WTP is the rupture of a 1-ton chlorine container, resulting in a release of 2,000 pounds of chlorine over a 10-minute duration. In practice this type of total release of a container would be unlikely to occur during the lifetime of the plant. The released liquid is assumed to quickly volatilize and to dispe rse 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 were included in completing this activity, including conservative meteorological conditions - a very stable atmosphere (F stability class), wind speed of 1.5 meters per second, highest daily maximum temperature of 43 degrees C (110 degree F), and average humidity (51 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 unlikely. Unlike the wors t case release scenario, active controls can be applied to minimize the leak or impacts. Active controls consist of mechanical, electrical, or human input. The alternative release scenario consisted of a chlorine gas leak from a leaking valve or fitting. This leak was assumed to be equivalent of a 1/16" (1.6 mm) diameter hole leaking for 10 minutes. An atmosphere stability class of D was used with a wind speed of 3 m/s, average daily temperature 18 degrees C (64 degrees F) and humidity of 51%. The results of the dispersion modeling analysis for this alternative release scenario indicate that this scenario has an offsite, but very limited, impact. Grass Valley WTP, as its name indicates, is located in a valley, surrounded by mountains. Should a release of chlorine occur, chlorine, being denser than air, would flow by gravity down the valley, away from public receptors. The closest residential community is located south of the facility across a mountain ridge. Because the prevail ing wind direction is to the north, it is unlikely that any chlorine release from the Grass Valley WTP would reach the community to the south of the facility. 1.5 Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps Grass Valley 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, 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 detectors and alarms. Grass Valley 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 investigation, inspection, and auditing program using qualified staff 1.5.1 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 info rmation has been compiled on the chlorine process, and specifications for each piece of equipment 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 process equipments are on file at the facility. 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. 1.5.2 Process Hazard Analysis In March 1999, a detailed process hazard analysis (PHA) was conducted with plant staff, engineering, and management staff for the regulated chlorine 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 ty pe 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 March 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 Grass Valley WTP for their evaluations and implementation. 1.5.3 Operating Procedures Grass Valley WTP maintains up-to-date, accurate, written operating procedures that give clear instructions for the chlorine processes. Grass Valley 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 systems. Procedures include startup, shutdown, a nd normal, alternate, and emergency operation. Also included are maintenance and troubleshooting procedures, including consequences of deviation and the steps to avoid correct deviations. Grass Valley 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 process equipment coming on line or a changed process starting back up. 1.5.4 Operations and Maintenance Training Program Each Grass Valley WTP employee presently involved in operating or maintaining the chlorine process is trained in an overview of the process and detailed, applicable operating and maintenance procedures. This training helps employees understand the nature and cause of problems arising from operations involving chlorine and increases employee awareness of the hazards. Grass Valley WTP's training program includes both initial and refresher training that covers: (1) a general overview of the process es, (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. 1.5.5 Contractors Grass Valley 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 process. 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. Grass Valley WTP sets minimum contractor safety performance re quirements 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. 1.5.6 Pre-Startup Safety Review and Mechanical Integrity Program Grass Valley WTP 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. Grass Valley WTP maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public, or the environment. Grass Valley 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. Grass Valley WTP's mechanical integrity program includes the following: 7 Written p rocedures 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 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 1.5.7 Hot Work Permits and Management of Change Grass Valley WTP requires employees and contractors to employ safe work practices when performing "hot work" in, on, or around the regulated processes. Grass Valley WTP uses a comprehensive permitting and training program to ensure hot work is conducted safely. Grass Valley WT P provides a system to manage changes or modifications to equipment, procedures, chemicals, and processing conditions. This system allows Grass Valley 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. 1.5.8 Internal Compliance Audits Internal compliance audits are conducted every 3 years to verify compliance with the programs and procedures contained in the RMP. Grass Valley WTP 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 enhancem ents to the prevention program are implemented. 1.5.9 Incident Investigation Grass Valley 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. Grass Valley WTP 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. 1.6 Five-year Accident History Summary N o chlorine releases that could have caused safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at Grass Valley WTP 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. 1.7 Emergency Response Program Summary Grass Valley WTP has established a written emergency response 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 response and notification plan. Emergency operation and response procedures are also reviewed once per year. 1.8 Planned Changes to Improve Safety The March 1999 PHA identified several changes or rec ommendations to improve the safety of the chlorination system. The recommendations include installing a remote hoist operation, ordering new materials for the process such as fiberglass gaskets, revising the refresher training course topics, and purchasing and making five minute escape air packs available in the event of emergency. It is expected that the recommended actions will be evaluated and implemented by October 1999. The implementation of these recommendations will further improve the safety of the covered process at Grass Valley WTP. |