SLO Lopez Water Treatment Plant - Executive Summary

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FEDERALLY MANDATED RMP SUBMISSION 
 
EXECUTIVE SUMMARY 
 
1. Accidental Release Prevention and Emergency Response Policies 
 
The County of San Luis Obispo uses chlorine at the Lopez Water Treatment Plant (SLOLWTP) for disinfection of a surface water supply before the water enters a water distribution system for use by County water users. 
 
The chlorine stored in the Chemical Building is liquefied chorine gas under pressure and is considered a hazardous material; Chlorine gas is also a Regulated Substance under the California Accidental Release Program (CalARP).  The San Luis Obispo County Health Department recognized the SLOLWTP as a Stationary Source under the CalARP regulations and requested this Risk Management Plan (RMP).  The County of San Luis Obispos policy is to adhere to all applicable Federal and State of California rules and regulations.  Safety depends upon proper construction design and safety features of the facility, accurate operating and emergency procedures, and effective  
training of personnel. 
 
2. Stationary Source and Regulated Substances 
 
The Chemical Building at SLOLWTP is a steel-frame / concrete slab shed located at 2845 Lopez Drive, east of the City of Arroyo Grande, California.  As a Stationary Source, there is one Federally Regulated Substance and Regulated Process that includes chlorine gas unloading and storage, a chlorinator, and the chlorine injector.  When chlorine gas is dissolved in water, it is no longer a Regulated Substance in the CalARP. 
 
The SLOLWTP is a conventional water treatment plant that includes coagulation, flocculation, filtration, and disinfection.  The facility treats the water from Lopez Lake for delivery to the unincorporated communities and cities in the South County, Arroyo Grande, Pismo Beach, Oceano, Grover Beach, and Avila Beach. 
 
The chlorine gas used in the disinfection process is trucked to the facility in one-ton containers.  Five one-ton containers are stored in the Chemical Building; Two of these one-ton cont 
ainers are connected to the chlorinator.  After the chlorine gas is dissolved in water in the chlorinator, the chlorine in solution is conveyed in underground conduit to the influent vault, the clear well, and the effluent vault. 
 
Near the effluent discharge point, a metal building houses an aqua ammonia injection system.  This chemical is added along with residual chlorine to extend the retention time of the chlorine in the distribution pipes.  The processes containing aqua ammonia do not exceed Federal threshold quantities.  
 
3a. Worst Case Release Scenario 
 
The Worst 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 vessels contents and usage as per the CCR Title 19 Division 2 Chapter 4.5 Article 2 Section 2750.3(b). 
 
One of the five 2,000-lb chlorine containers 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 110 lbs per minute for a ten-minute duration (release rate mitigated from 200 lbs per minute by the release occurring inside the building). 
 
The distance to the 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 is complete failure and separation of a quarter-inch fuse plug in the end of the container.  All 2,000 lbs of chlorine is assumed to flash to vapor. 
 
The distance to the end point of 3 ppm (0.0087 mg/L) would extend beyond the boundaries of the stationary source. 
 
3c. Administrative Controls 
 
Administrative controls to limit the distances for each reported scenario exist to restrict, to a minimum, the amount of chlorine lost from a one-ton container if an accidental releas 
e were to occur; and preferably to not have a release occur.  These administrative controls are inherent in the operational procedures for the chlorine unloading process system and the training provided to the operators.  Administrative controls are also in place for the regulated processes. 
 
3d. Mitigation Measures 
 
Mitigation measures to limit the distances for each reported scenario exist 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 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 implemented at the facility for the regulated proce 
sses and their related activities and equipment represents the facilitys main active commitments to an accidental release prevention program. 
 
5. Five Year Accident History 
 
There have been no accidental releases of regulated substances 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 to be initiated. 
 
7. Planned Changes To Improve Safety 
 
Current applicable codes and regulations are reviewed as part of the Process Hazard Analysis element of the Process Safety Management (PSM) program to determine if commitments need to be made to achieve increased operational safety for the regulated processes.  These commitments address prevention and mitigation measures for accidental releases of the regulated s 
ubstances.  The completion schedules for these commitments are included in the PSM.
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