Hemet/San Jacinto RWRF - Executive Summary

| Accident History | Chemicals | Emergency Response | Registration | Source | Executive Summary |

Eastern Municipal Water District (EMWD) has established a risk management plan according to EPA's regulations (40 CFR Part 68) to enhance already existing safety and emergency response programs.  EMWD is extremely cautious in the handling of all chemicals and is very diligent about safety for its employees and its communities. EMWD staff is highly trained and utilizes modern equipment to monitor its facilities to provide safeguards, while effectively employing these useful chemicals. These chemicals play an important role in water treatment and water reclamation, enabling everyone to lead healthier lives. 
Accidental Release Prevention and Emergency Response Policies 
Eastern Municipal Water District has an emergency response plan in effect to handle potential emergency situations at the Hemet/San Jacinto Regional Water Reclamation Facility (RWRF).  This Emergency Response Plan was designed to meet the following objecti 
1.) To save lives. 
2.) To minimize and avoid injuries. 
3.) To protect the environment. 
4.) To minimize property damage. 
The Eastern Municipal Water District Safety Officer is the designated emergency coordinator for the facility.  The District also maintains an on-call Emergency Response Team.  The Plan provides the response organization and notification procedures, evacuation routes, chlorine health hazards and mitigation procedures which will be implemented to respond effectively to emergency situations that may arise at the facility.  This Plan is reviewed and updated at least once per year and has been reviewed and updated to ensure compliance with the PSM, RMP and CalARP regulations 
Stationary Source and Regulated Substance 
The Hemet/San Jacinto RWRF maintains a maximum quantity of 36,800 pounds of chlorine on-site for use in disinfecting wastewater treated by the plant.  There is a single chlorination building located at the facility housing two 10-ton bulk storage tank 
s (maximum fill 92%).  These tanks are filled by the chlorine chemical vendor.  Chlorine gas is supplied from the bulk tanks to two chlorinators that regulate the chlorine feed rate via a pressure regulating valve that shuts off upon loss of vacuum downstream.  A vacuum is created at the chlorinators by water flow through a set of injectors.  
A chlorine scrubber is connected to the chlorine building.  Its sole function is to remove chlorine gas from the room in case of an accidental release from the system.  The scrubber is automatically activated by the chlorine detectors that are installed in the room.  At 1ppm the detector sounds an alarm in the central control room of EMWD and at 3 ppm the scrubber system is activated.  In the scrubber, the chlorine gas is reacted with sodium hydroxide.  The result of which is water and table salt.   
A dedicated emergency generator can provide power to the chlorination system and scrubber unit, in case of loss of city power. 
Hazard Assessment S 
Worst Case Release Result Summary 
Scenario Description: Release of the maximum quantity of chlorine that can be stored in the largest vessel - 18,400 pounds in 10 minutes.  The 10-ton-tanks are located in a building, therefore, this passive mitigation measure was incorporated in the calculations.  The most pessimistic meteorological conditions were used: 1.5 meters/second wind speed, and F stability (a measure for turbulence in the air).  Although the chlorination building is equipped with an automatically actuated scrubber system, it was considered to be inoperable for the purposes of this worst case scenario.  The reference chart included in EPA's RMP Guidance for Wastewater Treatment Plants was used to determine the maximum downwind distance to 3 ppm.  With these assumptions in place, the toxic plume extends offsite. 
Alternative Release Result Summary 
Scenario Description: The scenario consisted of a liquid release inside the chlorination building from a failure of a transf 
er hose with a release rate of 150 pounds per minute for  10 minutes, until the hose is drained and all emergency valves are shutoff (the time duration and total available liquid chlorine is considered to be very conservative).  The downwind distance estimated for this scenario is substantially less than that of the worst case.  However, it also extends offsite. 
Accidental Release Prevention Program and Chemical-Specific Prevention Steps 
The Eastern Municipal Water District 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, including common practices outlined by the Chlorine Institute.  In addition to the Management Programs, there are chlorine leak detectors situated in all rooms that contain chlorine.  In the event of a chlorine gas leak reaching 1 ppm, the detectors relay a signal that activates a horn and a light outside t 
he room where chlorine has been detected.  In addition, the alarm is displayed on the SCADA monitors. At 3 ppm, the alarm signal actuates the emergency scrubber system for the chlorination building. 
Five Year Accident History 
The five-year accident history (June 1994 through June 1999) for the Hemet/San Jacinto RWRF reveals that there were no incidents that involved a release of chlorine. 
Planned Changes to Improve Safety 
Several process and management system improvements were implemented during the development of the PSM Program for this site.  For compliance with RMP regulations additional improvements are being considered.
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