City of Paris Water Treatment Plant - Executive Summary |
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Executive Summary City of Paris, TX Water Treatment Plant The City of Paris maintains a policy to reduce or eliminate the possibility of any accident that could pose a threat to the health and safety of the public, employees and the environement. Potentially hazardous materials are inherent to the water utility industry and all employees are well trained in the safe handling of these materials and proper response to spills or leaks both major and minor. Engineering controls, training, written procedures and coordination with local emergency response entities are all combined to achieve our goal of maintaining the safest possible work environment. Procedures are routinely updated to meet changing needs brought about by new construction, process modification, new regulatory requireme nts, personnel input or any other factors that may result in a more efficient means of safe chemical management and emergency response. The City of Paris Water Treatment Plant is located next to Lake Crook dam two miles west of U.S. Highway 271 north of Paris in Lamar County, Texas. Chlorine liquified under pressure in one ton cylinders is injected as a gas in the disinfection of treated water in the operation of a public water supply. Chlorine is stored in a maximum quantity of 20 cylinders (40,000 lbs.) on a few occasions during peak water demand but a lesser quantity (12-14 cylinders) is more typical most of the year. This quantity results in the requirement for development of a Risk Management Plan (RMP) for chlorine over the threshold established under 40 CFR Part 68. Ammonia liquified under pressure is present also but below the threshold quantity required for specific RMP development. The procedures for responding to a release of chlorine under our RMP can b e used for a release of ammonia as well and is included in our overall plan of managing any hazardous spill or leak of gasses, liquids or solids used in water treatment. The worst case scenario uses a full release of the largest single vessel on site as required under 40 CFR Part 68 risk modeling guidelines. The EPA RMP Comp modeling program gives a distance to endpoint of 1.3 miles for a release of all 2,000 lbs. of chlorine from a single cylinder. The distance to endpoint is a planning model used to identify all public receptors such as residences, businesses, recreational areas and any other public places located within this 1.3 mile radius that could be at risk from such a release. The modeling program uses a conservative approach in identifying public receptors that may be at risk and an actual release would probably not travel a full 1.3 miles before dispersing to non toxic levels. Chlorine gas is 2.5 times heavier than air and would tend to remain in the low lying a reas near the treatment facility. Other factors limiting migration of a chlorine gas cloud would be dense mature forests around the facility, buildings, an earthen berm for liquid spill containment and the location of Lake Crook dam adjacent to the treatment plant functioning as an additional large berm. Evacuation of all individuals 1.3 miles downwind should provide a good safety factor to protect the public in the event of an actual release. In addition, evacuation in all directions of the release would protect the public in the event of a change in wind direction. Even though a worst case release would not likely reach the full 1.3 mile endpoint, it would surely have offsite consequences such as destruction of vegetation and other environmental impacts to the area. A worst case release scenario would be unlikely and even the Risk Management Program guidance manuals state that such an event would be rare. Preparation and response to a worst case release allows facilties to provide a maximum level of safety to protect the public from such an occurrance. An alternative release scenario was developed also to provide a model of a more realistic release that could be anticipated. The alternative release model uses a quantity of 50 lbs. of chlorine gas released from ruptured chemical feed pipe. This would most likely happen during a change in chlorine cylinders by personnel in taking empty cylinders off-line and placing full cylinders on-line. A release of 50 lbs. could reasonably be expected before personnel were able to manually shut off the chlorine gas feed from the cylinder in the event of a line rupture and this would involve a time period of 10 minutes. In an actual line rupture, a 10 minute period for manual shutoff would require an additional problem such as a stuck shut off valve. An actual line rupture with all equipment fully functional would more likely be shut off in a matter of seconds by trained personnel and would result in only a "puff" release of a very small quantity of chlorine gas resulting in no harm to personnel or equipment. The alternate release scenario model of a 50 lb. release predicts a distance to endpoint of less than 0.1 miles. All previously mentioned limiting factors in the worst case release such as berms, buildings etc. would be in place and no offsite consequences would be expected from a 50 lb. release of chlorine. Onsite damage to vegetation and some structural damage such as corrosion to equipment could be expected in the immediate vicinity of such a release. No reportable quantity release has occurred at the water treatment plant in the past five (5) years and none has ever occurred prior to this time period to anyone's knowledge. This record is good testimony to the training, maintenance and operational procedures employed by personnel in handling chlorine. However, this record cannot allow personnel to become overconfident and safety training and emergency response procedures must be stressed since the potential risk of an accident is present at all times. Water treatment plant operators and maintenance personnel must pass state certification tests given by the Texas Natural Resource Conservation Commission (TNRCC) to lawfully operate a water treatment facility. Specific training courses offered by the TNRCC and the Texas Engineering Extension Service (TEEX) are prerequisites to taking progressively higher certification tests. Chlorine is the most widely used disinfectant chemical in the water industry and safe handling procedures and potential dangers of chlorine is covered repeatedly in several of these required courses. The City of Paris Utilities Dept. requires all personnel (including secretarial personnel) to take the Water Utilities Safety course taught by TEEX even if the personnel are not required to hold a state certification. This allows all individuals to be knowledgeable of the hazards of treatment chemicals such as chlorine as well as mechanical hazards associated with the water industry. Additionally, personnel familiar with the hazards of chlorine (and other treatment chemicals) are able to respond more efficiently in the event of an actual release incident. Training is the major component of the facility release prevention program. Very few mechanical devices are involved in the storage and use of chlorine in the disinfection process of water treatment. These few devices and piping structures are routinely inspected and checked for proper operation and process area alarms are tested to insure proper function in the event of a chlorine leak. The chlorine vendor provides the various safety features of the cylinders and associated valves and fusible plugs in accordance with industry standards. Previously mentioned berms, surrounding structures and topography provide a measure of passive mitigation to minimize a chlorine release. Our emergency response plan does not utilize facility pe rsonnel to actually perform the corrective measures to control a dangerous release of chlorine gas even though self contained breathing apparatus are on site. These breathing apparatus are intended for use in the change of cylinders, control of minor leaks or retrieval of injured personnel in the event of an accident. These breathing apparatus are routinely tested for proper operation and are maintained in a fully charged state when not in use. The plan involves the prompt notification to local emergency management responders, evacuation to a pre-designated staging area and provide any first aid needed for injured or incapacitated personnel until emergency medical response personnel arrive. All relevant information such as type and quantity of leak, wind conditions, type of container and exact location is given to the emergency responders when they arrive. The designated staging area is along the access road to the facility and emergency responders must pass this point to reach th e site thus avoiding the possibility of the response team not obtaining the crucial information provided by evacuated personnel. The City of Paris Fire Dept. is the local emergency response entity for all hazardous leaks and spills. The Fire Dept. has protective chemical suits with airtight faceshields and helmets and air supply for entering hazardous atmospheres such as chlorine gas. They also have "B" kits for sealing leaking chlorine, sulfur dioxide and similar cylinders and conduct training drills at our treatment plant to familiarize their personnel in the proper use of this equipment in the event of an emergency. This training allows them to use this expertise for hazardous gas leaks that may occur at another facility or a transport accident involving trucks or rail cars. No changes are currently scheduled to our existing emergency response procedures but as previously mentioned in the introduction to this summary, the plan and procedures are routinely updated either by necessity or if a more efficient idea arises. One suggestion during our most recent safety meeting regarding our emergency plan was the installation of a facility siren or similar device that would more efficiently notify all personnel of a need to evacuate. This would be highly beneficial in providing a shorter response time for individuals working in areas and buildings away from the main building and a siren is currenly under strong consideration. The City of Paris welcomes any other suggestions or comments from others that may help make our current plan even better in protecting the safety of our citizens, personnel, property and the environment. Thank you. |