Northwest Water Treatment Plant - Executive Summary |
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1.0 EXECUTIVE SUMMARY 1.1 Accidental Release Prevention and Emergency Response Policies The Northwest Water Treatment Plant utilizes chlorine as part of the water purification process. Chlorine is considered a hazardous substance by the EPA, and is regulated under the EPA Risk Management Program (RMP) rules (40 CFR Part 68). This makes it necessary to observe safety precautions in handling chlorine in order to prevent unnecessary human exposure, to reduce the risk to on-site employees, and to reduce the risk to nearby members of the community. The Northwest Water Treatment Plant has coordinated emergency response measures with the Brunswick County Emergency Management Services (BCEMS). Representatives of BCEMS conduct periodic visits to the site, and have conducted SCBA training with facility personnel. In the event of an accidental release of chlorine or ammonia, facility personnel have been instructed to evacuate the facility and notify BCEMS of the nature of the emergency. B CEMS will notify appropriate local emergency response resources, and will respond to the release and attempt to bring the release under control. BCEMS will also notify the surrounding communities if evacuations are necessary and will notify additional emergency response agencies, as needed. 1.2 Stationary Source and Regulated Substances Handled The only regulated substance presently in use at the Northwest Water Treatment Plant is chlorine. Chlorine is used in the chlorine injection systems for water purification. Chlorine is received at the facility by truck, and is stored in eight one-ton steel cylinders. The cylinders are located in the main plant building, underneath the plant offices and control room. Access to the cylinders may be achieved through two doors, one leading to the inside of the building, the other to the parking lot, which are kept closed and locked when not in use. The maximum amount of chlorine that can be stored at the facility is 16,000 pounds. During normal operating conditions, two chlorine cylinders are hooked up to each chlorine injection system (east side and west side), and four unused chlorine cylinders are maintained as spares (two for each chlorine injection system). 1.3 Worst-Case Release Scenario The worst-case release scenario for chlorine assumes failure of the valve on one of the chlorine cylinders. The failure results in the release of the entire contents of one cylinder (2,000 pounds) over a ten-minute period. Since the release occurs indoors, the effective release rate is 110 lb/minute. The distance to the toxic endpoint for this worst-case release scenario was calculated using Bee-Line Softwares SLAB for Windows 95, version 5.00a. The calculated distance to the toxic endpoint of 0.0087 mg/L for this scenario is 1.86 miles. 1.4 Alternate Release Scenario The alternate release scenario for chlorine assumes failure of the piping, valve, or connection leading from one of the chlorine cylinders to the chlorine header line. The failure results in the release of the entire contents of one chlorine cylinder (2,000 pounds) over a sixty-minute period. Since the release occurs indoors, the effective release rate is 18.3 lb/minute. The distance to the toxic endpoint for this alternate release scenario was calculated using Bee-Line Softwares SLAB for Windows 95, version 5.00a. The distance to the toxic endpoint of 0.0087 mg/L for this scenario is 0.37 miles. 1.5 Five-Year Accident History The Northwest Water Treatment Plant has not had any incidents or accidental releases involving the chlorine injection systems since they were installed in June, 1987. 1.6 Emergency Response Program The Northwest Water Treatment Plant does not currently maintain a written Emergency Action Program (EAP). In the event of a chlorine release, the Northwest Water Treatment Plant has coordinated emergency response measures with the Brunswick County Emergency Management Services (BCEMS). 1.7 Planned Changes to I mprove Safety The Northwest Water Treatment Plant does not currently have any plans to upgrade or modify the chlorination system. The facility does plan to upgrade the system in order to comply with future changes to ASTM or ASME standards, or other standards pertaining to chlorine handling and storage. |