City of Kilgore Wastewater Treatment Plant - Executive Summary |
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The City of Kilgore places great emphasis on safety and utilizing safe practices in handling the various chemicals used in the wastewater treatment processes. The City is committed to the safety and well being of its employees as well as the community. This commitment comes from each employee, from the plant operators to the City Manager and City Commission. The wastewater treatment plant (WWTP) provides the facilities and equipment designed to treat the wastewater generated from the residences, commercial and industrial facilities in the City. This treatment is designed to meet the standards as set forth by the Environmental Protection Agency and the Texas Natural Resource Conservation Commission to provide adequate treatment to the wastewater that it may be discharged to the receiving waters of the State without harm to the environment. One of the primary chemicals used in this treatment is chlorine, which is used in the disinfection of the treated wastewater to kill any pathoge nic (disease causing) bacteria in the effluent from the plant. Chlorine is a greenish yellow gas with a sharp, irritating, bleach-like odor. At low concentrations chlorine becomes colorless but it retains its characteristic odor. It is commonly used to disinfect water and wastewater, bleach woodpulp, and to make other chemicals. Before chlorine became widely used as a disinfectant early in this century, waterborne diseases such as cholera, dysentery, and typhoid killed hundreds of thousands every year. In 1900, 25,000 people died from typhoid just in the United States. Due to chlorine, these deaths in the U.S. were reduced to fewer than 20 in 1960. Long term exposure to low concentrations or short-term exposure to high concentrations may result in adverse health effects from inhalation. In high enough concentrations, chlorine will cause severe irritation to the eyes, coughing and difficulty breathing. Chlorine does not burn but will support combustion (lets other articles bur n). The vapors are much heavier than air and tend to settle in low areas. The City maintains a supply of not more than 6000 lbs. (3 cylinders of 1 ton capacity each) at the wastewater treatment plant. To evaluate the potential hazards to the community, two scenarios were considered as required. These scenarios were evaluated using the EPA's RMP Comp modeling program. The first, or worst case scenario, assumes a complete failure of one of the 1 ton chlorine cylinders, releasing the entire contents into the surrounding area within 10 minutes. If this were to happen, the estimated distance the chlorine gas would travel would cover a radius of approximately 1.3 miles from the source, and could affect an estimated 1,353 people. This scenario is highly unlikely, due to the industry safeguards designed into the cylinders. For example, chlorine cylinders are ruggedly designed and DOT approved. A protective cap covers the cylinder valves at all times when the cylinder is not in use. Th e cylinders are also equipped with pressure relief devices to prevent rupture of the cylinder if exposed to heat. Special chlorine regulators are used which automatically shut off the flow of chlorine if the feed pipe breaks. Additionally, chlorine cylinders and process piping are located and installed to minimize the potential damage from impact. Another more reasonable scenario evaluated for emergency planning purposes involves having one of the = inch valves used to withdraw chlorine from the cylinder break off. Should this happen, the estimated distance the chlorine gas would travel would be to a radius of about 0.1 miles, possibly affecting approximately 17 people according to the model. The same safeguards mentioned above, as well as the prevention program outlined below, also make the likelihood of this happening significantly low. The City is in compliance with the rules for extremely hazardous substances as set froth in EPCRA ' 302. In addition specific operation and ma intenance procedures are followed to prevent an accidental release of chlorine. Chlorine cylinders are unloaded and handled by special equipment designed specifically for cylinder handling. Cylinders are stored and used away from flammable liquids and gases. Trained personnel following established written procedures are used to connect or disconnect a chlorine cylinder. These people have safety equipment readily available, which would allow them to safely remain and close the cylinder valve if a leak occurred while changing out the cylinder. Gaskets, valves, and connections are visually inspected each time a chlorine cylinder is changed. Chlorine cylinders are inspected on a routine basis and are approved by the DOT. Only one cylinder is connected to the process at each location to minimize the impact of a leak. There have been no accidental releases of chlorine in the past five years that resulted in deaths, injuries, or significant property damage on-site, nor known off-site deaths, injuries, evacuations, sheltering in place, property or environmental damage. The City maintains an emergency response program with the Gregg County LEPC through the City's fire department. In addition, the City is a supporter of the First Call emergency notification system. General emergency response practices include the following: - The City maintains a community emergency notification plan. - Response is coordinated with emergency response agencies in the community. - The City has radio communication capability with County emergency response agencies. - A telephone emergency notification system is being put into operation to provide quick, concise emergency information to the City's near neighbors. - Emergency response personnel regularly take training to comply with all federal, state, and local requirements. Response practices specific to chlorine include the following: - Water system operators trained and provided with proper personal protection to allow them to respond to a chlorine leak, and stop the leak. - Special repair kits are maintained which provide fittings and tools to quickly stop a chlorine cylinder leak. - Self-contained breathing apparatus (SCBA) is located on site to allow operators to enter leak area safely. To ensure the continued safety of City personnel and the community, the City will review policies and procedures as they relate to chlorine handling and emergencies, and make changes as necessary to improve the program. Personnel will continue to be trained in safe practices, and be updated on any new technologies that may help maintain and improve chlorine handling facilities. |