City of St. Helena Wastewater & Reclamation Plant - Executive Summary |
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EXECUTIVE SUMMARY 1. Accidental Release Prevention and Emergency Response Policies The City of St. Helena uses chlorine at the Wastewater And Reclamation Plant (WWRP). The chlorine is a liquefied gas under pressure and are hazardous materials. Chlorine is a regulated substances under the Federal Accidental Release Program (ARP). The properties of chlorine make it necessary to observe safety precautions in handling the chlorine to prevent human exposure. The City of St. Helena's policy is to adhere to all applicable Federal rules and regulations. Safety depends upon proper design and safety features of the facility, accurate operating and emergency procedures, and effective training of personnel. 2. Stationary Source and Regulated Substances The WWRP is a stationary source which has regulated processes in the storage and usage of chlorine. The WWRP uses chlorine to disinfect the treated wastewater to prevent the spread of pathogenic organisms before the effluent is discharge d into the Napa River when the effluent is not discharged to the land application. The chlorine process includes the one ton container of chlorine delivery/pickup, storage and usage. The usage for the chlorine in this RMP extends from the one ton container until the chlorine is dissolved in solution at which it is no longer considered a regulated substance. The chlorine is delivered to the facility in one-ton containers by a commercial supplier. Four one-ton containers of chlorine are present at the WWRP. One of the one-ton containers of chlorine is connected on-line and another one ton container of chlorine is connected on standby to the chlorinator and injector. Two of the one ton containers of chlorine are kept in storage until needed for the usage process. After the chlorine gas is dissolved in water by the injector, the chlorine in solution is conveyed in separate underground conduit to the chemical injection point (contact chamber). 3a. Worst Case Release Scenario The W orst Case release scenario for interconnected equipment must consider 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 the CCR Title 19 Division 2 Chapter 4.5 Article 2 Section 2750.3(b). One of the one ton containers of chlorine is considered the largest vessel in the chlorine feed system. The one-ton container is, at most, filled with 2,000 lb of liquid chlorine. The Worst Case release scenario for the one-ton container is the release of the entire capacity at a rate of 200 lbs per minute in a ten-minute duration. The distance to the end-point of 3 ppm (0.0087 mg/l) would extend beyond the boundaries of the stationary source. 3b. Alternative Release Scenario The Alternative Release scenario for the one ton container of chlorine is leakage from the gas valve on the one ton container at a rate of 2 lb/min for 60 minutes for a total release of 120 lb . The distance to the chlorine end point of 3 ppm (0.0087 mg/l) would extend beyond the boundaries of the stationary source. 3c. Administrative Controls Administrative controls are in place to limit the amount of chlorine in one ton containers at the WWRP. Administrative controls exist to limit the end-point distance and to restrict the amount of chlorine lost to a minimum if an accidental release were to occur; and preferably to not have a release occur. These administrative controls are inherent in the operational procedures for the chlorine process system and the training provided to the operators. 3d. Mitigation Measures Mitigation measures to limit the end-point distance and to restrict the amount of chlorine released to a minimum, if a release were to occur; and preferably to not have a release occur. The mitigation measures are based on the design, inspection, testing, and maintenance of the regulated processes and their related equipment and components. 4. General Acci dental 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 implemented at the facility for the regulated processes and their related activities and equipment represents the facility's main active commitments to an accidental release prevention program. 5. Five Year Accident History There have been no accidental releases of the regulated substance within the last five years. 6. Emergency Response Program The Emergency Response Program is based upon the alerting of personnel at the facility to evacuate or shelter-in-place and await the arrival of responders from the local area responder at the assembly location if a release occurs that causes the evacuation or the shelter-in-place respectively to be initiated. The Napa County - Environmental health can incorporate this response into the Area Pla n 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) program 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 there are further commitments that need to be made to achieve increased operational safety for the regulated processes. These commitments will be prevention and mitigation measures for the accidental releases of the regulated substances. |