San Juan Chlorine Distribution Center - Executive Summary |
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Compaqma 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 distribution of chlorine, a regulated toxic substance, from the San Juan Chlorine Distribution Center. 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. Chlorine is a hazardous toxic substance regulated by EPA, OSHA, and PROSHO. Due to the hazardous characteristics of chlorine, the San Juan Chlorine Distribution Center observes various safety precautions in the distribution of chlorine. The safety precautions are necessary to protec t employees, contractors, and visitors at the San Juan Chlorine Distribution Center 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 Chlorine is used at PRASA's water filtration plants, wastewater treatment plants, and pumping stations for disinfection and for odor control. Ton containers and 150 pound cylinders of chlorine are received at the San Juan Chlorine Distribution Center from the supplier, then are distributed by truck to the various water filtration plants, wastewater treatment plants, and pumping stations. Empty containers and cylinders are brought back from the plants to the San Juan Chlorine Distribution Center, then are returned to the supplier for inspection, servicing, and for refilling. Worst-case and Alternative Relea se 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 ton container over a ten minute period (200 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. 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 concentration 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 miles from the chlorine storage area. The following are known to be within the zo ne of vulnerability for the worst-case release scenario: residences, school, commercial/industrial areas, airport, and recreation areas (river, park, and beach). Approximately 21,000 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 Analysis Guidance. The alternative release scenario is a vapor release of the entire contents of a ton container through a broken valve. If the leak was not stopped, the contents would be released at a rate of 84 pounds of chlorine per minute over a 24 minute period. More typical weather conditions are also 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 and no mitigation of the release). The zone of vulnerability for the alternative release scenario is determined to extend 0.2 miles from the chlorine storage area. Approximately 3 residents are located within a 0.2 miles 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 Prevention Steps CAPR complies with PROSHO requirements for Prevention Programs and for Process Safety Management. Security guards, drivers, and contractors are informed of chlorine hazards, and hazard signs are posted in the chlorine storage area. Standard operating and maintenance procedur es have been developed, and employees who work with chlorine are provided training. Emergency Response Program CAPR has an emergency response program. Leak repair kits are maintained on site, and drivers 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. All CAPR facilities are scheduled to receive refresher training by September 30, 1999. Five-year Accident History Within the past five years there 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 identif ied from a PHA are then addressed in CAPR's Prevention Program. Assessments of the chlorine processes were conducted during April and May 1999 for each CAPR facility. Documentation of the formal PHA for this facility will be completed by July 20, 1999. An audit of the RMP and PSM programs will be conducted within three years to verify the effectiveness of the program. |