City of Mount Vernon Wastewater Utility - Executive Summary

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City of Mount Vernon 
Wastewater Utility 
Risk Management Program 
Executive Summary 
 
 
The Federal Clean Air Act Section 112(r) accidental release prevention rules promulgated under Title 40 Part 68 of the Code of Federal Regulations requires affected facilities to institute chemical release and prevention mitigation procedures and submit risk management plans (RMPs).  These requirements are intended to lessen the risk of catastrophic chemical releases. 
 
To implement this RMP, Mount Vernon is integrating applicable elements of the Emergency Preparedness & Response Plan, Process Safety Management program, and General Safety Program, with Risk Management Plan requirements.  This RMP is required by the Clean Air Act, as is the WISHA Process Safety Management Program.  Integrating these requirements will enhance each plan and better assure full compliance.  The RMP report will be submitted in a method and format specified by EPA. The RMP will be coordinated with other responsible and interest 
ed agencies, which include the Northwest Air Pollution Authority NWAPA, Department of Labor and Industries, and Skagit County Department of Emergency Management.  
 
Accidental release prevention and emergency response policies at the Wastewater Treatment Plant. 
 
Employee involvement and training are the key components in preventing an accidental release of chlorine.  Essential to the success of this program is the development of expertise, experience, judgement, and proactive initiative within the workforce. The Process Safety Management plan establishes methods and procedures to prevent unwanted releases of chlorine.  The PSM plan is a systematic approach to evaluating the whole process.  Using this approach the process design, process technology, operational and maintenance activities and procedures, non-routine activities and procedures, emergency preparedness plans and procedures, training programs and other elements which impact the process were all considered in developing the acc 
idental release and emergency response policies. 
 
The stationary source and regulated substances handled at the Wastewater Utility. 
 
Chlorine is the single regulated substance handled at the Mount Vernon WWTP as listed by CAA 112(r ) CAS Number, 7782-50-5.   Chlorine is a respiratory irritant and severe exposures may be fatal.   
 
To prevent interruption of the wastewater disinfection process, two one ton chlorine containers are on line at any given time.  The maximum combined volume of two containers equals 4000 pounds of liquid chlorine.  From the chlorine container, chlorine gas is piped to the chlorinators.  The chlorinators adjust chorine dosage in proportion to the wastewater flow. From the chlorinator, chlorine gas is piped to the chlorine mixing structure where it is injected into the wastewater flow via a submerged mixing pump. 
 
The worst-case release scenario(s) and the alternative release scenario(s), including administrative controls and mitigation measures to limit the dist 
ance for each reported scenario.  
 
The worst case release scenario at the Mount Vernon WWTP involves a failure of two containers.  Each container carries a maximum of 2000 pounds of liquid chlorine.  The chlorine can be released in the form of liquid or gas depending on the location of the failure.  The worst case scenario assumes a 4000-pound liquid release. The alternate release scenario assumes a 300-pound liquid release.    
 
The worst case release and alternate release was determined using EPA's Risk Management Plan for Wastewater Treatment Plants.  This software system is provided to EPA by the Chemical Emergency Preparedness and Prevention Office (CEPPO). 
 
Major Findings - Worst Case Scenario 
7 The distance to endpoint = 1.3 mile 
7 Estimated population within distance to endpoint = 5,000 
7 Public receptors within distance to endpoint are; schools, residences, hospitals, prisons, recreation areas, major commercial and office areas, Interstate 5, Burlington Northern Railroad system 

 
Major Findings - Alternate Release Scenario 
7 The distance to endpoint =  0.1 mile 
7 Estimated population within distance to endpoint = 500 
7 Public receptors within distance to endpoint are; residences and recreation areas. 
 
The general accidental release prevention program and chemical specific prevention steps. 
 
The general accidental release prevention program is contained in the Process Safety Management Plan.  This plan includes the following elements: Employee Participation, Process Safety Information, Process Hazard Analysis, Operating Procedures, Training, Contractors, Pre-Startup Safety Review, Mechanical Integrity, Hot Work Permit, Management of Change, Incident Investigation, Emergency Planning and Response, and Compliance Audits.   
 
Chemical specific steps for preventing a chorine release begin with the design.  The Mount Vernon WWTP uses a vacuum chlorine feed system. When a drop in vacuum occurs the chlorine feed shuts off at the vacuum/pressure regulator automatic s 
witchover valve.  This feature greatly diminishes the potential catastrophic release from any portion of the system beyond the container and dip tube.   
 
Another important chemical specific prevention step is the supply contract.   Mount Vernon's supply contract and operation policy require an inspection of each container prior to delivery.  The contract establishes maintenance requirements for the cylinder, valves, fusible plugs and other appurtenances.  The contract requires that each container must be suitable for use of the Chlorine Institute "B" Leak Repair Kit.  
 
The five-year accident history. 
 
No accidental releases have occurred at the Mount Vernon WWTP in the past five years. 
 
The emergency response program. 
 
The Wastewater Utility's PSM plan covers emergency response procedures for chlorine releases.  Wastewater Utility Staff are trained in chlorine leak assessment and repair as required by WAC 296-62-300 (Hazardous Waste Operations and Emergency Response Standard - HAZWOPE 
R).  The Wastewater Utility emergency response plan is coordinated with the City of Mount Vernon Emergency Preparedness and Response Plan.  When an emergency threatens or strikes, the City of Mount Vernon will take the initial lead in managing emergency public health, safety and welfare services.  The response may be widespread, extending beyond the usual boundaries of the departments providing emergency services and requiring the cooperation of governmental and private sector units which do not ordinarily respond to emergency situations.  The Wastewater Utility Process Safety Management Plan specifically addresses the catastrophic release of chlorine.  Mount Vernon's Emergency Preparedness and Response Plan has been prepared to serve as a device for better, more efficient internal communication and to provide a basic understanding of duties and responsibilities in the process of addressing emergency assistance for all citizens.  Planning prior to a disaster is the sensible, logical wa 
y to begin to cope with an emergency in order to minimize the associated trauma of suffering loss of life, injury, and property damage.  Other problems at the time of disaster center on communication, coordination, and mobilization.  This Emergency Preparedness and Response Plan seeks to address these solutions and provide direction for appropriate actions and solutions. 
The integrated PSM/RMP outlines specific activities that must be undertaken to meet responsibilities stipulated in Mount Vernon's Emergency Preparedness and Response Plan.   
 
Planned changes to improve safety. 
 
The current Wastewater Utility Capital Improvement plan includes improvements to the WWTP disinfection system around the year 2003.  The planned improvements include replacing the existing chlorine disinfection system with Ultra-Violet.  This changeover to Ultra-Violet disinfection will enable Mount Vernon to utilize lower quantities of chlorine or other less hazardous chemicals.  
 
Currently the WWTP is explorin 
g system methods that could potentially reduce the quantity of chlorine on line or in service to less the 2500 pounds. 
 
Prior to June 21, 1999, the Wastewater Utility is participating in a pilot project that coordinates review of the RMP and PSM plan with representatives of the Northwest Air Pollution Authority and the Department of Labor & Industries.    The findings of this review will be incorporated into the integrated program. 
 
 
 
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