Lanier Filter Plant - Executive Summary |
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The use of chlorine at the Lanier Filter Plant has been ongoing since the original construction of the plant in the mid 1970's. Chlorine is used as a disinfectant at the Lanier Filter Plant to protect consumers from potentially harmful microoganisms (such as Giardia, Legionella, coliforms, viruses, etc.) that may be present in the raw water supply (Lake Lanier). Although the use of chlorine has been known to produce various regulated disinfection byproducts in the finished water, the use of chlorine is required by the Safe Drinking Water Act and by the Georgia Environmental Protection Division (GAEPD). The use of chlorine has been effective at the preventing waterborne outbreaks since the mid 1970's. Disinfection byproducts associated with chlorine are below the regulated levels as regulated by the Safe Drinking Water Act and water quality criteria established by the Georgia Environmental Protection Division. At the present time, chlorine is delivered to the Lanier Filter Pla nt in one-ton chlorine containers by a chemical supplier. Under normal operating conditiions, the Lanier Filter Plant will have up to 25 tons (13 in service and 12 in storage) of chlorine at any given time. The maximum amount of chlorine at the site is 35 tons, but this amount is rarely (if ever) located at the facilitiy. These chlorine containers are connected to a pipeline system (designed exclusively for the transport of chlorine gas) and delivered to three chlorinators. The chlorinators operate under vacuum conditions and deliver chlorine gas to a chlorine injector. The injector mixes the chlorine gas into a water stream that makes a concentrated chlorine solution. The chlorine solution is then applied to the appropriate application point at the water treatment plant to insure adequate disinfection is provided as required by the Surface Water Treatment Rule. A chlorine residual is also maintained in the distribution system to protect the distribution from potential outside c ontamination and to control microbial populations within the distribution system. Accidental chlorine releases can be caused by a multitude of reasons. In the event of a chlorine release (either small or large) employees are routinely trained on how to safely retain chloirne releases. The plant also has a detailed standard operating procedure (SOP) that clearly identifies how to unload chlorine containers, hook up chlorine containers, startup the chlorinators, and how to disconnect chlorine containers. In addition to the above, employees are required to conduct walk through inspections of the chlorine facilities 12 times a day (every 2 hours) and document any potential problems that may occur. In accordance with the guidance documents published by the Environmental Protection Agency (EPA) the worst case release will result in a toxic endpoint that will be approximately 1.3 miles around the Lanier Filter Plant. The worst case release will likely result from a fire in the chlorine storage area that could cause the fusable plugs on the chlorine contianers to melt and release the entire contents of the chlorine containers. To prevent this from occuring, the chlorine storage area is constructed almost entirely out of non flamable materials (concrete and steel). It is estimated that approximately 1,500 people would be impacted by the worst case release. A release of this magnitude could potentially cause illness or physical damage to people within this impact zone. The alternative release case, which represents a more realistic chlorine release, will result from a break in the chlorine gas transfer line. This release may produce a release rate of 196 pounds a minute for a duration of 2 hours and will produce a toxic endpoint of 0.3 miles around the Lanier Filter Plant. To prevent this from occuring, all chlorine gas transfer lines are constructed with steel piping with numerous closure valves located at strategic locations. Chlorine monitors and alarms a re also present that will promply alert the operators that a chlorine release is occuring. Containment of this type of release will occur by closing the appropriate chlorine valves. It is estimated that approximately 100 people could be potentially exposed to chloine levels that may cause illness or physical damage. In the event of a chlorine release, an emergency response plan has been developed that identifies the operational and managerial procedures used to evaluate and determine if a plant evacuation is necessary. The plan addresses the procedures for responding to minor and major chlorine releases and describes evacuation plans for the employees, contractors, and visitors, at the Lanier Filter Plant. At the time of this submittal, there has been only one documented chlorine release at the Lanier Filter Plant within the past five (5) years. This release occured in April 1999 and was caused by a valve failure in a chlorne gas transfer line. The valve was quickly isolated an d repaired. It is estimated that approximately one pound of chlorine gas was released during this event. Although the Lanier Filter Plant has an outstanding safety record, the Process Hazard Review Team did identify several areas in the disinfection operations that could be improved that will enhance the reliability and safety of the disinfection deficiencies. These items are documented in the RMP Plan and can be reviewed at the Lawrenceville and Buford-Sugar Hill public libraries. The County is currently evaluating new facilities that will either (a) replace and upgrade the existing chlorination facilties with more modern and safer facilities, or (b) replace the existing chlorine facilities with sodium hypochlorite facilities. It is anticipated that the proposed facilties will be operational by June 2001. |