City of Grandville Wastewater Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY The City of Grandville Wastewater Treatment Plant has used chlorine gas for disinfection and microorganism selection since the Plant first began treating Wastewater in the 1960's. There has been one reportable accidental chlorine gas release, which occurred approximately 20 years ago. Chlorine has proven its effectiveness in disinfection and protecting the Public Water supplies. However chlorine, when mishandled, can be dangerous and even deadly. Each Operator at the Plant recognizes these dangers and his or her responsibilities to his fellow Operators and the Public when working with the Chlorination Process. The Michigan Department of Environmental Quality requires that the Plant disinfect the effluent (as confirmed by daily bacterial testing) and then remove most of the chlorine (also confirmed by daily chlorine residual testing) prior to discharge into the Grand River. Our job is to comply with these requirements in the safest and most effective way possibl e. What follows is an explanation of what Grandville Wastewater Plant is doing to carry out its job safely and effectively. TRAINING 1. New Employee Training - Each new employee must complete a training process that usually takes a minimum of two months. The program is specific and documented with trainer and employee signing off in all listed areas. Much of the training involves safety procedure and the chlorination process. 2. On-going Employee Training - Each month the Plant Operators are involved in a safety meeting or activity often involving the chlorination process. In addition the City encourages educational development with various seminars and classes sponsored by various organizations including the Michigan Department of Environmental Quality. Most classes identify safety issues and often involve the chlorination process. 3. A virtual library of information is maintained at the Plant and contains chlorine process and safety information. Employees are encouraged to av ail themselves of these materials. Operator certification is encouraged and the City provides financial incentives to reach certain levels of certification. INSPECTIONS 1. Plant personnel participate on a rotational basis in conducting Plant Safety Inspections BI-annually. Results of these inspections are published for all to read. Management then addresses the concerns of the inspections and all material is documented. 2. The City has contracted with a Loss Prevention Specialist who visits the Plant approximately BI-annually and provides advice in improving the safety measures taken at the Plant. 3. Approximately every other year MIOSHA inspects the Plant and issues recommendations for improvements. 4. All employees have participated in a Process Hazard Analysis of the Chlorination Process. MECHANICAL INTEGRITY 1. Maintenance personnel at the Plant utilize a computerized preventive maintenance system to address Process components. Each day a checklist is generated which lists daily work assignments. Product suppliers provide a maintenance schedule for their process components, which are included in the work assignments. Records of the work performed are maintained a minimum of three years. 2. Product Operation and Maintenance Manuals as well as blueprints of the system are provided and accessible to all Operators. OPERATIONS 1. Operators are provided checklists and task summaries, which are specific to their workshift and limit their area of responsibility. Tasks involving the chlorine process are usually accomplished by the more highly trained and skilled employees usually working in pairs. 2. When unscheduled repairs or potential emergency situations arise, employees with special skills are on call on a rotational basis, 24 hours a day, seven days a week. 3. Tasks involving delivery of chlorine containers or changing of the ton container involve two operators, one of which provides some assistance but primarily acts as an observer to make sure proper procedures are being adhered to. PROCESS EFFICIENCY When the various processes at the Wastewater Plant are operating efficiently, a high quality effluent that requires lower levels of chlorine to attain bacterial reductions can be provided. The Plant usually produces an effluent quality much better then required by its discharge permit. It does so by addressing the following areas. 1. The Plant has conducted an Industrial Pre-Treatment Program which insures that discharges will not reduce Plant efficiencies, directly interfere with the process, or necessitate pre-treatment at the Plant with chlorine. 2. In the past the Plant has used chlorine to destroy and inhibit certain microorganisms that upset Plant processes. In so doing the desirable organisms are sometimes reduced resulting in lower treatment efficiencies. Approximately three years ago the Plant personnel experimented with a physical method of microorganism control which has worked very effectively. Since that method w as introduced, no chlorine has been necessary for microorganism control and effluent quality has improved. 3. Strict control and monitoring of all treatment process's, along with quick reaction to developing problems have helped to maintain a higher level of treatment resulting in a reduced need of chlorine to disinfect. EMERGENCY PROCEDURES 1. The Plant provides a chlorine emergency center in the Garage area. At this center are emergency instructions and phone lists in the event of a chlorine leak. Also available at this location are a telephone, self-contained Breathing Apparatus, protective clothing, and a ton-cylinder repair kit. 2. Although personnel have been trained in the use of the equipment, the local Hazardous Materials Team would do the actual work of containing and stopping a leak. 3. Procedures and coordination have been established with the Kent County Emergency Planning Committee and Offsite Response Standard Operating Procedures are updated yearly. 4. Chlorine g as sensing alarms are in place in the chlorine cylinder room which sense chlorine gas at very low levels therefore allowing early attention to any developing leak. These alarms are maintained and tested according to a set schedule. ACCIDENTAL RELEASE The Kent County Emergency Planning Committee has done a computer analysis on the vulnerability zones in the event of total release of chlorine gas from a chlorine cylinder. Different scenarios are possible depending on rate of release, wind speed and weather conditions. Within the vulnerability zone there is an estimated 2000 people, which would have the possibility of being affected. Evacuation plans and notification lists have been established. If the release occurred within the building there would be some containment. Hills and depressions may also serve to reduce the progress of a gas release. CONCLUSION Although the possibility of accidental release is possible, the City will continue to take the previously des cribed measures to minimize risk. The recent change to a gas induction system has greatly improved the efficiency of the disinfection process and reduced chlorine consumption by nearly fifty percent. This along with efficient Plant Operations have greatly reduced the number of chlorine deliveries and the number of times Operators must change chlorine containers (both times of increased vulnerability to risk). Finally, it is the intention of the City to change to alternate measures of disinfection. Development of Ultra-violet light disinfection may allow the City to eliminate or at least greatly reduce the need for chlorine gas. Present plans are to have ultra-violet light disinfection replace chlorine gas sometime in the year 2001. |