CITY OF MONROE WASTEWATER TREATMENT PLANT - Executive Summary |
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CITY OF MONROE WASTEWATER TREATMENT PLANT U.S.E.P.A. RISK MANAGEMENT PLAN EXECUTIVE SUMMARY JUNE 18, 1999 City of Monroe Risk Management Team Russell Colbath, Director of Water Resources Allen Killough, Water Treatment Plant Superintendent Brian Keith, Water Treatment Chief Operator Kim Hinson, Wastewater Treatment Plant Superintendent Kyle Ketchum, Wastewater Treatment Chief Operator Ray Smith, Safety and Risk Management Coordinator Ron Fowler, Public Safety Captain INTRODUCTION In compliance with the U.S.E.P.A. Risk Management Plan rule, 40 CFR Part 68, the City of Monroe Water Resources Department, working with other City departments to form a risk management program team, has completed a comprehensive plan to protect public health and the environment from accidental releases of hazardous chemicals at the City's water and wastewater treatment plants. A summary of the plan is presented below. The full plan can be viewed on-site at either treatment facility, or at the City of Monroe Operations Center. City of Monroe management and employees have a strong dedication to providing a safe environment for the citizens of the community, as well as the safest possible working environment. The City's COMET program (City of Monroe Team Safety) has provided a proactive approach to this goal. FACILITY AND PROCESS DESCRIPTION The City of Monroe Wastewater Treatment Plant (WWTP), with a capacity of 9 million gallons per day, provides wastewater treatment services to over 25,000 customers. The WWTP produces an effluent meeting stream quality standards consistent with NPDES permit NC0024333. To protect public health, chlorine gas is used to disinfect the wastewater prior to discharging treated effluent to Richardson Creek. Chlorine gas is one of the most common, reliable, and cost effective chemical used in the United States today for wastewater disinfection, and when properly used ensures destruction of pathogenic organisms that may occur in do mestic wastewaters. Chlorine gas is delivered to the WWTP in one ton containers. Up to five one ton containers can be on site at any one time, with two hooked up for active service and two hooked up and in standby mode. The safe handling and use of chlorine gas is a top priority for all employees at the WTP. PROCESS SAFETY AND ACCIDENTAL RELEASE PREVENTION The quantity of chlorine in use at the WWTP qualifies the facility for both the OSHA process safety management and EPA risk management plan rules. A comprehensive risk management and accident prevention program has been established at the facility. The program goal is to minimize the risk of accidental chlorine release thereby creating a safe environment for citizens and employees. The plan is made up of the following components: 7 Chlorine System Inventory - a comprehensive list and description of every piece of equipment related to the chlorination process. This serves as an excellent resource for employee training and f or developing/analyzing operation and maintenance procedures. 7 Process Hazard Analysis - The RMP team performed a thorough analysis of every aspect of the chlorination process, from initial delivery of chlorine inventory, to injection into the water leaving the WWTP. The team utilized the "what-if/checklist" methodology approved by OSHA in their hazard evaluation. 7 Operation and Maintenance Procedures - Detailed procedures have been developed to ensure safe and proper operation of the chlorine system. Critical maintenance intervals have been established for all appropriate equipment. 7 Employee Involvement and Training - Employee performance and readiness, through training and involvement, is the cornerstone of the process safety program. In addition to O & M training, employees receive training in recognizing safety and health hazards, emergency operations, safe work practices, and hazard communications. The City's goal is to have every WWTP employee trained as a hazardous materials "technician level responder" within two years of hiring as an operator. The City also requires that any contractor working at the WTP receive basic training concerning the chlorine hazards present. 7 Process Controls - The WWTP utilizes local and remote instrumentation to monitor chlorine process flows, pressure, etc. Leak detection alarms are employed to alert personnel immediately in the event of an accidental release of chlorine. EMERGENCY ACTION PLAN AND CHLORINE RELEASE SCENARIOS The City of Monroe maintains an emergency action and response plan for the WWTP. The plan provides emergency procedures for all types of hazards including an accidental release of chlorine. Technician level response to an actual release would be coordinated between City Public Safety and Water Resource Department personnel. The City maintains mutual aide agreements with surrounding jurisdictions to assist in case of an emergency. Mock emergency training drills are conducted annual ly. Pursuant to the RMP rule, the City conducted air dispersion modeling to evaluate the effect of an accidental chlorine release on the surrounding population and environmental receptors. Two release scenarios were required, "worst case - a catastrophic failure of a one ton cylinder" and "alternative - a failure of a 3/8 inch piping connector on a ton cylinder ". In each, the distance (radius) to a 3 mg/l concentration of chlorine, and the number of people within this radius was determined. Population estimates inside the effected radii were determined using aerial photography of the area surrounding the WWTP and assumed dwelling unit densities. It is important to note that a 3 mg/l concentration will result in minor irritation to the nose and mucous membrane if breathed, but that concentrations above 25 mg/l are needed to cause unconsciousness or death. Model Scenario Radius Population Worst Case 9,500 feet 3715 Alternative 1,550 feet 220* *WWTP staff not included SAFETY AS A WAY OF DOING BUSINESS As indicated by the extensive chlorine accident prevention program presented above, safety is, and will continue to be a way of doing business at the City of Monroe Wastewater Treatment Plant. Incident investigation procedures are in place to ensure that any accident or "near miss" will be thoroughly investigated and corrective actions taken. In the past five years there has been only one minor accidental release of chlorine at the WWTP. This occurred during a chlorine cylinder change-out and was caused by a mud wasp nest in connection piping. A very small quantity of chlorine gas, estimated to be less than one pound, was released. No evacuation or injuries occurred offsite. One WWTP employee was treated for minor symptoms related to chlorine inhalation. A process safety audit will be conducted annually to verify that essential elements of the prevention plan are being practiced and revised as needed. The City of Monroe Water Reso urce Department will continue to examine safety improvements at the WWTP by evaluating alternative disinfection methods as technologies develop and by evaluating improved mitigative controls that can cost effectively be installed. |