Graham Hill Water Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY 1. Accidental Release Prevention and Emergency Response Policies The City of Santa Cruz's Water Treatment Plant (WTP) located at 715 Graham Hill Road uses chlorine which is considered a hazardous material and is a regulated substance, which is considered in the Risk Management Plan (RMP). The properties of chlorine make it necessary to observe safety precautions in handling chlorine to prevent human exposure, and to reduce the threat to the facility's workers and nearby members of the community. It is the facility's policy to adhere to all applicable Federal and State rules and regulations. Safety depends upon the safe procedures used to handle chlorine; the safety devices and systems designed and constructed into the facility; and the training of the pertinent personnel. 2. Stationary Source and Regulated Substances Handled The WTP is designed to disinfect the treated water to prevent the spread of bacteria and pathogenic organisms. Chlorine is delivered b y a commercial supplier in one-ton containers for use at the WTP. Off-loading of the one-ton container from the commercial delivery vehicle is accomplished with a two-ton hoist. The one-ton containers are placed in the chlorine storage area on a steel frame. One of the one-ton containers is on-line inside of a containment vessel, another one ton container is on stand-by inside of another containment vessel. The delivery/pickup, storage, and handling of chlorine are considered a part of one complete process. The treatment facility has administrative procedures in place to limit the amount of chlorine at the facility. Delivery of chlorine one-ton containers is during normal working hours. The driveway provides adequate room for the delivery and parking of the delivery vehicles during the off-loading of the full one-ton containers, and the loading of the empty one-ton containers. The chlorine building is closed when not occupied. No unauthorized personnel is allowed entry into the chlorine building. The container storage and handling is conducted pursuant to per Sections 2.6, 2.7, and 2.8 of the Chlorine Institute's Chlorine Manual. The WTP operates twenty four hours per day, seven day a week. The chlorine gas is withdrawn from the one-ton containers by vacuum. This vacuum is created by water passing through the injector nozzles. This vacuum opens the vacuum regulator diaphragm, and withdraws the gas from the one-ton container at a controlled feed rate set by the chlorinator. The chlorine gas is injected into the water, where it becomes a chlorine/water solution and is feed where it is needed in the treatment process. The chlorine storage room and chlorinator room have a ventilation system, chlorine leak detectors, and alarm systems. The chlorinators are vented to the outside if the diaphragm malfunctions. WTP personnel are trained to use self-contained breathing apparatus (SCBA). 3a. Worst Case Release Scenario The Worst Case release scenario must consid er the largest quantity of a regulated substance handled on site in a single vessel at any time, taking into account administrative controls on the vessel's contents and usage as per 40 CFR Part 68 Section 68.25. The one-ton container of chlorine is the largest vessel size in the chlorine system located at the WTP. The Worst Case release scenario to be modeled for the one-ton chlorine container assumes that the full 2,000 pounds of chlorine is released over a ten minute period resulting in a release rate of 200 pounds per minute. This chlorine release will extend beyond the boundaries of the WTP. 3b. Alternative Release Scenario The Alternative Release scenario for chlorine for the one-ton container located at the WTP assumes a release from a valve packing, resulting in an estimated release of 2 pounds per minute. The period of release is taken to be one hour in duration, resulting in a total release quantity of 120 pounds. This chlorine release will extend beyond the boundaries of the WTP. 3c. Administrative Controls Administrative controls exist to restrict to a minimum, the amount of chlorine lost from a one-ton container if accidental release were to occur. This administrative control is inherent in the operational procedures for the chlorine process system and the training provided to the operators of the process system. 3d. Mitigation Measures Mitigation measures to limit the distances for each reported scenario exists to restrict the amount of chlorine released to a minimum if released were to occur. The mitigation measures are based upon the design, inspection, testing, and maintenance of the chlorine process and containment vessel systems; their related equipment and components. 4. General Accidental Release Prevention Program and Chemical Specific Prevention Steps The facility complies with all applicable federal and state codes and regulations. There are safety meetings and safety training. The Process Safety Management (PSM) program impl emented at the facility for the chlorine process system and the related activities and equipment represents the facility's main active commitments to an accidental prevention program. 5. Five Year Accident History There has been no accidental release of chlorine in the last five years. 6. Emergency Response Program The Emergency Response Program is based upon altering personnel at the facility to evacuate the facility and await the arrival of the first responders at the evacuation assembly location if a release occurs that causes the evacuation to be initiated. Santa Cruz County - Environmental Health can incorporate this response into the Area Plan for the Local Emergency Planning Committee. 7. Planned Changes to Improve Safety There are commitments made under the Process Hazard Analysis element of the Process Safety Management (PSM) and the RMP that are planned to be implemented over the next year. Current applicable codes and regulations are reviewed as part of the PSM and RMP to determine if the other commitments need to be made to achieve increased operational safety for the regulated chlorine process system. These commitments will be prevention and mitigation measures for the accidental releases of the regulated substance. |