Quebradillas Filtration Plant - Executive Summary |
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Compania de Aguas de Puerto Rico (CAPR) as operator of the Puerto Rico Aqueduct & Sewer Authority (PRASA) system has developed a Risk Management Plan (RMP) for management and prevention of risks associated with the storage and use of chlorine, a regulated toxic substance, at the Quebradillas Water Filtration Plant. The RMP was prepared in compliance with 40 CFR Part 68 and Clean Air Act (CAA) Section 112(r)(1). The Prevention Program elements build upon the facility's Process Safety Management (PSM) system prepared in compliance with 29 CFR Part 1910.119. Accidental Release Prevention and Emergency Response Policies It is CAPR's policy to comply with applicable Federal and Puerto Rican requirements. The chlorination process at the Quebradillas Water Filtration Plant uses chlorine, a hazardous toxic substance regulated by EPA, OSHA, and PROSHO. Due to the hazardous characteristics of chlorine, the Quebradillas Water Filtration Plant observes various safety precautions in the stora ge, conveyance and use of chlorine. The safety precautions are necessary to protect employees, contractors, and visitors at the Quebradillas Water Filtration Plant and the immediately surrounding areas. Safety precautions include procedures and equipment to minimize the potential for accidental release, as well as a written emergency response program for response to any chlorine release that may occur. The Stationary Source and Regulated Substances Handled The Quebradillas Water Filtration Plant supplies up to 3.0 million gallons per day of water to the surrounding community. Chlorine is used to disinfect the water, destroying microorganisms that could cause illness in humans. Chlorine is delivered to the facility via truck in 2,000 pound containers. The storage building has space for up to three full containers, a total of 6,000 pounds of chlorine. Chlorine cylinders are connected to vacuum chlorinators. The chlorinators regulate chlorine use. From the chlorinators, chlorine gas is distributed under vacuum to injectors. The injectors combine the gaseous chlorine with water. The chlorinated water is mixed with the water plant flow for disinfection. Worst-case and Alternative Release Scenarios The worst-case release scenario was determined following EPA's Risk Management Program Offsite Consequence Analysis Guidance. The worst-case release scenario is a vapor release of the entire contents of a 2000 pound container over a ten minute period (200.0 pounds of chlorine per minute). Other worst-case assumptions required by EPA include a low wind speed (1.5 meters per second), stable atmosphere (Class F), urban topography, and no active mitigation of the release. The storage room enclosure would provide passive mitigation of the release. EPA requires the determination of the area (zone of vulnerability) which may be exposed to a chlorine concentration of 3 ppm or greater. According to the American Industrial Hygiene Association, 3 ppm is the maximum conc entration of chlorine in air below which nearly all people could be exposed for one hour without serious health effects. Based on the worst-case assumptions, the zone of vulnerability was determined to extend 1.3 mile from the chlorine storage area. The following are known to be within the zone of vulnerability for the worst-case release scenario: residences, schools and religious institutions. Approximately 2,100 residents are located within a 1.3 mile radius of the chlorine storage area. Many of these residents would not actually be impacted in even a worst-case release, as the chlorine would travel in the direction of wind. No known environmental receptors (such as state parks or officially designated wildlife preserves) are located within the zone of vulnerability. The conditions and parameters for the worst-case scenario are specified by EPA. A more realistic alternative release scenario was examined, also following EPA's Risk Management Program Offsite Consequence Analysi s Guidance. The alternative release scenario is a vapor release of the entire contents of a 2000 pound container through a broken 3/8 inch flexible connector tube. If the container was nor shut off the contents would be released over a 95 minute period (21.0 pounds of chlorine per minute). More typical weather conditions are used (wind speed of 3.0 meters per second, atmospheric stability Class D). Other conditions remain the same as in the worst-case scenario (urban topography, passive mitigation of the release by the storage room enclosure). The zone of vulnerability for the alternative release scenario is determined to extend 0.1 mile from the chlorine storage area. Approximately 20 residents are located within a 0.1 mile radius of the chlorine storage area. These residents could be impacted, depending on the direction of wind. No known environmental receptors are located within the zone of vulnerability. General Accidental Release Prevention Program and Chemical-specific P revention Steps CAPR complies with PROSHO requirements for Prevention Programs and for Process Safety Management. Operators, maintenance staff and contractors are informed of chlorine hazards, and hazard signs are posted in the chlorine storage area. Standard operating and maintenance procedures have been developed, and employees who work with chlorine are provided training. Emergency Response Program CAPR has an emergency response program. Chlorine gas detectors are located within the storage area for early detection and warning of any leak. Leak repair kits are maintained on site, and operators are trained in how to quickly stop any leak that may occur. The emergency response program is coordinated with Civil Defense for notification of the public. CAPR periodically conducts various training programs, including emergency response training. Thisl CAPR facility is scheduled to receive refresher training by 09/14/2000. Five-year Accident History Within the past five years th ere have been no unplanned releases of chlorine in excess of 10 pounds resulting in injuries or significant property damage on site; or known offsite injuries, evacuations, sheltering in place, property damage, or environmental damage. Planned Changes to Improve Safety CAPR uses Process Hazard Analyses (PHA) to identify and recommend changes to ensure a high level of safety. Issues identified from a PHA are then addressed in CAPR's Prevention Program. Assessments of the chlorine processes were conducted during April, May and December 1999 for each CAPR facility. Documentation of the formal PHA for this facility was completed on 2/16/2000. An audit of the RMP and PSM programs will be conducted within three years to verify the effectiveness of the program. |