Cowlitz Water Pollution Control - Executive Summary |
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The Cowlitz Water Pollution Control facility uses gaseous chlorine for disinfection and sulfur dioxide for dechlorination purposes. The facility is located in an industrial area and has a maximum inventory of 6 tons of chlorine and 3 tons of sulfur dioxide. One worst case and two alternative release scenarios were determined for this RMP submittal. The document "EPA Risk Management Guidance Document for Wastewater Tratment Plants" (EPA 550-B-98-010) was consulted to develop these scenarios. The worst case scenario involving a 2000 lb release of chlorine in a 10 minute period indicates a 1.3 mile toxic endpoint distance. Alternative scenarios involving one-half inch vessel leaks for chlorine and sulfur dioxide suggest only a 0.1 mile endpoint distance. No accidents or releases involving these chemicals have occurred during the past 5 years. On site and off site risks have been reduced by use of PSM guidelines, process equipment maintenance procedures, employee training, and leak detectors. Due to pending expansion and improvements to the facility, it is expected that RMP regulated chemicals will be phased out of use by the 4th quarter of the year 2000 or early 2001. |