WATER TREATMENT PLANT - Executive Summary |
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The City of Statesville management and Water Treatment plant management are committed to the safe and environmentally sound operation of the Water Treatment Plant. In providing water services for the City, the Water Treatment Plant must use chlorine as a disinfectant to ensure proper treatment and maintain public health. The Water Treatment Plant has safely operated a chlorination process for over 40 years through an aggressive chlorine safety program including standard operating procedures and training. The Water Treatment Plant is a 12.0 million gallons per day (MGD) facility that treats and supplies 6.0 MGD of drinking water on the average. Incoming raw water is chemically treated, filtered and chlorinated with the use of chlorine and then supplied to the distribution system. In the chlorination process, treated wastewater is chlorinated using equipment (a chlorinator) designed to mix chlorine gas with water to make a chlorine solution. The treated water is allowed to mix with the chlorine solution in a contact chamber. The chlorine kills pathogens that are dangerous to humans that remain in the treated water after filtration. Chlorination of drinking water ensures that public health is preserved. Per EPA requirements 40 CFR Part 68, chlorine is a regulated toxic chemical and therefore processes utilizing over 2,500 pounds of chlorine must implement Risk Management Plan (RMP) requirements. The Water Treatment Plant stores a maximum of six one-ton chlorine cylinders (approximately 12,000 pounds of chlorine) and is therefore subject to RMP requirements. The Water Treatment Plant is also subject to OSHA Process Safety Management (OSHA PSM) requirements (29 CFR 1910.119). The worst case, toxic release scenario that was evaluated for the Water Treatment Plant assumes chlorine is released as a gas into the environment. The release is assumed to empty a one-ton (2,000 pounds) cylinder in ten minutes. The area impacted is down wind at a distance of 1.3 miles . The alternative toxic release scenario evaluated was identified through the OSHA PSM process hazard analysis review of the chlorination process. Through this process hazard analysis, it was identified that the most likely release that could occur would be due to piping failure on the chlorine vacuum supply line. In this scenario, the release was assumed to come from a horizontal one-ton chlorine cylinder that was feeding gaseous chlorine. Approximately 634 pounds of chlorine would be released in approximately 27 minutes. The area impacted by this release is down wind at a distance of 0.72 miles. In order to prevent toxic releases of chlorine from the chlorination process, the Water Treatment Plant complies with the OSHA PSM standard. PSM requires that Water Treatment Plant's prevention program include process safety information, process hazard analysis, operating procedures, training, mechanical integrity, management of change, pre-startup review, compliance audits, incident i nvestigation, employee participation, hot work permitting and contractor guidelines. Operating standards are in place such that all aspects of equipment operation and maintenance for the chlorination process are covered. The facility is required to conduct inspections of equipment, test emergency procedures and train employees in all aspects of process safety. Further, the process is monitored by a chlorine gas detection monitor and alarm and operators are trained to thoroughly inspect process equipment daily. The Water Treatment Plant has not had a chlorine release in the past five years. Emergency response to accidents and releases is coordinated with the Statesville Fire Department's Hazardous Materials Response Team (HAZMAT Team). In the event of a chlorine accident or release, Water Plant personnel are trained to notify the HAZMAT team and evacuate personnel upwind and to high ground. Through coordination with the Iredell County ECOM, all of the effected surrounding area wou ld be evacuated. |