Neenah Water Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY Of The RISK MANAGEMENT PROGRAM For the Neenah Water Utility, Neenah Wisconsin I. INTRODUCTION A. Neenah Water Utility's Approach The Neenah Water Utility owns and operates a 12.0 million gallon day (MGD) water treatment plant on South Park Avenue in Neenah, Wisconsin. The Neenah Water Plant provides an average of 5.0 MGD of treated water to approximately 24,000 customers in the City of Neenah. The primary source of water for the water plant is Lake Winnebago. The water plant has a second intake in the Fox River, which is seldom used. Chlorine gas is stored and used at the water treatment plant in a quantity above the EPA Risk Management Program (RMP) regulations and the Occupational Health & Safety Administration (OSHA) regulations. The State of Wisconsin Department of Commerce (DOC) governs the Neenah Water Utility in lieu of OSHA. The DOC has adopted the OSHA PSM rule, but has extended the deadline to September 1, 2000. The Neenah Water Utility has el ected to develop a Program 3 Risk Management Program, completing the PSM over one year ahead of schedule. The Process Safety Management (PSM) standard is a comprehensive management system for the handling of highly hazardous chemicals. The PSM requires facilities to carefully evaluate each aspect of the chemical handling process, including developing written operating procedures, providing operator training, developing preventive maintenance schedules and procedures, and evaluating equipment and procedures for safety. The PSM resulted in several improvements to the chlorine system. By developing the PSM, the Neenah Water Utility has made the facility safer for its employees and the surrounding community. The Neenah Water Utility and its employees are fully committed to the safe handling of chlorine for the protection of its employees, the surrounding community, and the environment. B. Purpose of Chlorine The Neenah Water Plant provides safe drinking water to its customers in the City of Neenah. Treatment at the Water Plant includes lime softening, filtration, fluoride addition, and disinfection. Chlorine gas is used to disinfect the treated water before it is pumped to the distribution system. The addition of chlorine gas is the most common method of disinfection. Disinfection is the killing of microorganisms in water, including essentially all pathogenic (disease-causing) organisms. In addition, chlorine is also added to water prior to filtration during the summer months to aid in the removal of algae and other organics in Lake Winnebago water. Chlorine gas is also piped underground to the municipal pool for disinfection purposes. C. Chlorine Storage & Handling The maximum amount of chlorine stored at the water treatment plant is 8,000 pounds. Chlorine is delivered and stored at the facility in one ton cylinders. The cylinders are constructed of approximately = - inch welded steel, and are inspected by the supplier after each use. The cylinders a re stored in a fireproof enclosed room. A maximum of four cylinders are stored at the facility at one time. Chlorine gas is removed from the one ton chlorine cylinders to the point of application through a vacuum system. The vacuum system consists of a gas feeder mounted directly to the cylinder, PVC gas piping, and an ejector at the point of application. The vacuum to operate the system is developed by pumping water through the ejector. The water pumped through the ejector absorbs the chlorine gas. The vacuum created by the ejector opens the valve of the gas feeder, initiating gas flow. The primary advantage of the vacuum system is safety. If a line break occurs, or vacuum is lost for any reason, the gas feeder will automatically shut-off the flow of chlorine gas from the cylinder, preventing a release. II. RELEASE SCENARIOS A. General A requirement of the Risk Management Program (RMP) rule is that the facility develop the distance to endpoint of the worst-cast and al ternate hypothetical chemical release (leak) scenarios. The distance to endpoint is the estimated distance from the facility to where the concentration of chlorine gas in the atmosphere is less than the EPA level of concern (0.0087 mg/L). The area influenced by a release would be greatly determined by the wind direction and speed. The distances to endpoint were determined using the Areal Locations of Hazardous Atmospheres (ALOHA) computer simulation. ALOHA was developed by the National Safety Council for use by emergency responders and for those involved in emergency planning. The local HAZMAT team uses ALOHA in actual emergency response situations. The chlorine cylinders are stored in an enclosed room at the water plant. Both release scenarios assume an outdoor release, which would only occur when the cylinders are delivered to the facility. Therefore, it is more likely that a release would occur when the cylinders are in the Chlorine Cylinder Room. The room should substantia lly mitigate or contain the chlorine gas, reducing the impact of the release. B. Worst-Case Release Scenario The conditions of a worst-case release scenario are defined by the EPA RMP rule, and are not site- specific. The worst-case scenario assumes a catastrophic cylinder failure, and the following worst-case atmospheric conditions: 1. Wind Speed = 3.4 mph 2. Temperature = 93 deg. F 3. Relative Humidity = 75% 4. Atmospheric Stability = Class F (very light wind, late night, partial cloud cover) The distance to endpoint of the worst-case release scenario is 2.6 miles. The risk of the worst-case release scenario is very low. It combines an improbable catastrophic cylinder failure with worst-case weather conditions. A book published in 1992 stated that there has been only one known one ton cylinder failure by rupture. Ton cylinders have been in use for over 60 years. C. Alternate Release Scenario The alternate release scenario is a more site-specific scenario and is more sui table for emergency response planning. The alternate release scenario modeled for the Neenah Water Plant is a leak through the 5/16-inch gas valve on a full chlorine ton cylinder. The gas feeder is mounted directly to the gas valve. The alternate release scenario uses the average atmospheric conditions for the area as determined by the Midwest Climate Data Center. The conditions of the alternate release are as follows: 1. Wind Speed = 9.7 mph 2. Temperature = 45 deg. F 3. Relative Humidity = 75% 4. Atmospheric Stability = Class E 5. Total amount released through valve = 298 pounds The distance to endpoint of the alternate release scenario is 891 yards, or 0.51 miles. This type of release would more-than-likely occur in the enclosed Chlorine Cylinder Room, which should reduce the impact of this release. III. FIVE-YEAR ACCIDENT HISTORY The Neenah Water Utility has not had a significant release of chlorine at its Water Treatment Plant in the last five years. In fact, there are n o records of a significant release in the history of the facility. The water plant has been in operation since 1933. IV. ACCIDENTAL RELEASE PREVENTION PROGRAM A. General The Neenah Water Utility Prevention Program follows the guidelines provided in OSHA's 1910.119 Process Safety Management Standard. The Neenah Water Plant has several procedures and controls in place that contribute to the safe handling of chlorine. B. Controls Chlorine cylinders are stored in an enclosed room, separate from the other processes at the facility. The Chlorine Cylinder Room has a chlorine gas detector that sounds a plant alarm in the event of a chlorine release. The chlorine cylinders are stored on weigh scales that allow the operator to verify the feed rates of the chlorine feed system, and verify the cylinder is empty before removing from service. As previously mentioned, chlorine is removed from the chlorine cylinders through a vacuum feed system. In the event of a piping leak or rupture, the gas feeder on the cylinder will automatically shut-off the flow of chlorine at the cylinder. The piping system also has a vacuum pressure transmitter that allows the operator to monitor the vacuum in the piping system. In the event of a piping leak or low vacuum condition, the transmitter will warn the operator of the condition through a low vacuum alarm. The vacuum feed system has an automatic switchover module that will automatically switch from one ton cylinder to another when empty. This allows operators to change the gas feeder on the cylinder at a later time when adequate personnel are available. C. Procedures The Neenah Water Utility has several operating procedures in place for the protection of its employees and the surrounding community. The operators at the plant understand that chlorine is a hazardous chemical that must be treated with respect. The water plant is staffed 24-hours a day. Operators must follow written operating procedures. Two operators must be pre sent at all times when working in the Chlorine Cylinder Room. The most common task in the room is the changing of chorine cylinders. One operator must wear a Self-Contained Breathing Apparatus (SCBA), while the second operator wears an approved cartridge mask when working in the room. The SCBA and mask allow the operators to safely evacuate the room in the event of a leak and warn others. In addition, the SCBA and mask may allow the operator to respond to a simple leak (i.e. close valve), preventing an occurrence of a significant leak with off-site impacts. When changing cylinders, the operators check all connections for leaks with ammonia vapor before placing the cylinders on-line. All operators receive safety and emergency response training. V. EMERGENCY RESPONSE PROGRAM The Neenah Water Utility relies on the area HAZMAT Team and local responders to handle a chemical release at its facility. Therefore, the Neenah Water Utility is not required to develop an Emergency Response Program. The Water Utility has taken a pro-active role in coordinating response actions with local emergency responders to ensure they are prepared to respond to an emergency at the facility. An Off-Site plan has been developed by the Neenah Water Utility and the Local Emergency Planning Commission (LEPC) for handling a chemical release. Further, a superintendent at the water plant is on the LEPC. In addition to ensuring that local responders are prepared to handle a chemical release at the facility, the Water Utility has developed a Chlorine Leak Policy for its operators. The Policy includes safety procedures and steps for dealing with a chlorine release. One of the goals of the procedure is to isolate the release in the enclosed room, reducing the impact of the release on the surrounding community. The local HAZMAT Team would be responsible for gradually releasing the chlorine in the room to the atmosphere in a controlled manner. In the event of a leak, the following procedu res will be initiated. 1. Evacuate Chlorine Cylinder Room and shut doors. 2. Turn off ventilation fan in room. 3. Warn employees at the plant over the intercom system. 4. Call 911. 5. Call Municipal Swimming Pool. 6. Grab SCBA. 7. Employees should meet at a specified upwind location. 8. An employee should be stationed at pool side of the plant to keep children away. 9. Be prepared to assist local responders. VI. PLANNED CHANGES TO IMPROVE SAFETY The Process Safety Management Program has resulted in several improvements to the operating procedures, emergency response procedures, and Chlorine Cylinder Room that should improve the safe handling of chlorine. The Neenah Water Utility has accepted bids for an Emergency Shut-Off System on the chlorine ton cylinders. In the event of a leak, an operator can activate the system by pushing a button outside the room. The system will close the valve on the chlorine cylinder, stopping the release through the valve. |