March Wastewater Treatment Plant - Executive Summary |
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The March Air Force Base Wastewater Treatment Plant (March WWTP) is owned by the United States Air Force. Western Municipal Water District (Western) operates the March WWTP, with its chlorine disinfection system, under contract. Western has established a risk management plan according to EPA's regulations (40 CFR Part 68) to enhance already existing safety and emergency response programs. Western staff is highly trained and utilizes modern equipment to monitor its facilities to provide safeguards, while effectively employing the sterilizing ability of chlorine. Chlorine plays an important role in wastewater treatment and water reclamation, enabling everyone to lead healthier lives. Accidental Release Prevention and Emergency Response Policies Western has an emergency response plan in effect to handle potential emergency situations at this facility. This plan was designed to meet the following objectives: 1.) To save lives. 2.) To minimize and avoid injuries. 3.) To protect the en vironment. 4.) To minimize property damage. Key elements of the Emergency Response Plan include specific steps that Western management expect its employees to take to protect health of the employees and the community. The plan includes key phone numbers and contact points, vicinity and evacuation maps, plans for evacuation, fire, injury, earthquake, chemical spill, and health hazards. Stationary Source and Regulated Substance The chlorination system at March WWTP is used for the disinfection of wastewater from March Air Base after treatment at the plant, which is then used for irrigating the nearby military cemetery and golf course. Chlorine is stored in one-ton containers and a few 150-lb cylinders in the Chlorination Building. These containers are owned, maintained and filled by the chlorine chemical vendor per Department of Transportation regulations and standards. Two ton-containers are connected to the process. The connected containers are placed on a scale to allow We stern operators to plan ahead for ordering more chlorine and for the change-out procedure. One additional container is stored in the room (but off-line) for replacement of an empty container. Each connected container is positioned so that the valves are vertically aligned. The process piping is connected to the top valve of each ton container to ensure that chlorine gas is drawn out of the container. As a safety feature, the top valve of each connected container is attached to a vacuum regulator with a shut-off control. This ensures that the downstream portion of the system operates under a vacuum. A vacuum is created when process water flows through an injector. This flow generates a vacuum (approximately 1-3 in. Hg) which opens the vacuum regulator. Upon loss of vacuum in the system (which may be caused by a breach in the chlorine piping), a diaphragm in the vacuum regulator will close, stopping any chlorine from escaping. Any chlorine in the piping upon loss of vacuum will be drawn through the chlorine feeders and into solution. Hazard Assessment Summary Worst Case Release Result Summary Scenario Description: Release of the maximum quantity of chlorine that can be stored in the largest vessel - 2,000 pounds in 10 minutes. The most pessimistic meteorological conditions were used as specified in the regulation. The reference table included in EPA's RMP Guidance for Wastewater Treatment Plants was used to determine the maximum downwind distance to 3 ppm concentration. The result shows that offsite areas may be affected. Alternative Release Result Summary Scenario Description: A release of chlorine gas from 1/4-inch diameter leak. This simulates a more realistic, however unlikely, event than the worst case scenario. The meteorological conditions specified in the regulation for alternative scenarios were used. The reference table included in EPA's RMP Guidance for Wastewater Treatment Plants was used to determine the maximum downwind distance to 3 ppm. The downwind distance for this scenario is significantly less than for the worst case scenario. Accidental Release Prevention Program and Chemical-Specific Prevention Steps Western has a Process Safety Management program in place to manage the handling of chlorine. In addition, common industry standards, policies, and procedures are utilized to ensure safe practices are being performed. This includes common practices outlined by the Chlorine Institute. In addition to the Management Programs, there are chlorine leak detectors situated in the chlorination area. In the event of a chlorine gas leak reaching 3 ppm, the detector alarms locally and to the Western SCADA system. Five Year Accident History There have been no reportable releases of chlorine at the facility in the past 5 years. Planned Changes to Improve Safety Several process and management system improvements were recommended during the development of the PSM Program for this site. These measures are being im plemented or are under consideration. |