Water Treatment Plant - Executive Summary |
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Greenville Utilities has implemented a comprehensive program to safely manage chlorine at its Water Treatment Plant located northwest of the City of Greenville, North Carolina. There have been no chlorine incidents in the most recent five-year history period. In 1997 and 1998, a Process Safety Management (PSM) program was initiated at the Plant with the assistance of Operations Excellence Consulting, Inc., a consulting organization. A general PSM program was initially presented to the Plant. With this step, approximately 50% of PSM requirements were met. Key items included in the program were: written procedures for employee involvement, management of change, incident investigation, pre-startup plus self-audits and forms for use in conjunction with the above procedures. Next, the PSM program was edited to be site specific. These additional steps were implemented to complete the PSM program: (1) development of Chlorine Safety Information, (2) training on PSM and its key components including management of change, mechanical integrity and incident investigation, (3) conducting a process hazards analysis for the chlorine process, (4) developing standard operating procedures for chlorine management, (5) training in support of the certification of operators, and (6) conducting a self-audit with a written program. The superintendent, supervisor, chief operator, safety officer and several plant operators will meet several times per year to review and update procedures and to maintain compliance with all aspects of the PSM regulation. This Risk Management Program was developed from the PSM and expanded to include the additional necessary items. With the developed offsite consequences study/modeling for the RMP, we determined both a worst case and alternate case release of the chlorine gas. The plant location does provide a good green belt surrounding the facility that w ould provide some natural barrier in case of a release. The worst case release probability is extremely low based on the safety factors built into the system and the history of operation since 1980 without any significant release. The worst case release based on modeling, could impact 2.5 miles but the maximum short term exposure limit reached 1,577 yards. This type release could reach areas of northwestern Greenville, including the airport and surrounding residential neighborhoods with some impact. The alternate case release, which also has not been experienced in the Plant's history, has a maximum threat zone reaching 87 yards which with prevailing wind speed and direction, is still on the Plant property. With chlorine gas being heavier than air, the release could travel to the uninhabited low grounds where the heavy green belt would contain and dissipate it. Greenville Utilities has started Plant expansion work for increased capacity that will also eliminate chlorine gas as the disinfecting agent. Other chemicals will be used to perform this work when this expansion is completed as estimated for 2001. |