WRP #7 - Executive Summary |
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POLICY STATEMENT It is the policy of the Coachella Valley Water District to conduct all district activities safely to prevent job related accidents, illnesses and injuries to employees and others and damage to district and others' property. A well organized safety program provides a safe working environment and promotes increased efficiency at all levels. (IIPP) ACCIDENT HISTORY None to report WORST-CASE RELEASE SCENARIO This facility used EPA's "Risk Management Program Guidance For Wastewater Treatement Plants (40CFR Part 68)" for performing offsite consequence analysis (OCA) for the worst-case leak scenario. The worst-case leak scenario is described in the compliance guide as the largest container losing all of it's contents in 10 minutes, this equates to a 200 lb/min leak of chlorine gas. This facility is in a rural area and using the tables given in the compliance guide, a leak of this magnitude would effect a radius from the plant to 3.0 miles. It is unlikely that a leak o f this magnitude would occur because the process system is inspected daily and the chlorine containers are located in a brick building that is monitored 24 hours a day for process leaks and all buildings have intruder alarms to guard against vandalism. All plant operators and a Chlorine Response Team are trained to respond to and stop process leaks. ALTERNATIVE LEAK SCENARIO This facility used the same guide as mentioned above to perform the OCA for the alternative leak scenario. A Process Hazard Analysis (PHA) was performed on the chlorine system at WRP #7 and it was determined that a more likely (yet not likely) leak scenario than the worst-case scenario , would be from the rupture or separation of the flexible connections from the 1-ton containers to the manifold system. This could occur through an earthquake, vandalism or material defects, but the mitigating factors that make these situations unlikely will be explained in another paragraph. Using the EPAs guide, a leak as desc ribed above would come from a 5/16 inch opening (size of opening in valve body) producing a release rate of 15 lbs/min effecting radius of 0.2 miles from the plant. It is unlikely that a leak described above would occur because of the following: The process system is inspected daily; the chlorine system is monitored 24 hours a day for process leaks, and the alarms self test daily and manually tested weekly; all building have intruder alarms to guard against vandalism; the flexible connections are replaced annually as per manufacturers recommendations; all 1-ton containers are bound with two chain binders each to prevent movement in case of an earthquake and finally all plant operators and a Chlorine Response Team are trained to respond to and stop process leaks. RESPONSE TEAMS Chlorine response and any work with chlorine connections require three employees. All plant operators are trained in emergency response. The crew of employees trained in response to chlorine leaks at domesti c well sites have been trained to respond to chlorine gas leaks at the WRPs as well. This two person crew will respond to plants after hours with the standby operator to unmanned plants or to plants that need assistance. There will always be three employees on call with pagers ready to respond to chlorine leaks. The employees on call for chlorine response are rotated weekly. TRAINING Chlorine response personnel are scheduled quarterly to be trained in use of emergency repair kits, personal protective equipment and emergency response procedures; scheduled annually to be trained in the hazards and handling of chlorine & CPR/First Aid. The district has purchased a 1-ton container and a 150 lb cylinder to practice emergency repairs. ALARMS WRP #7 is equipped with chlorine gas detectors that will alarm at 1.0 ppm and at 3.0 ppm at the plants alarm page of the computer and to the Control Operator located in Coachella. The Control Operator will be able to let the responders know which a larm is activated. The chlorine gas concentrations are also transmitted to a LED readout located on the north wall of the chlorine building. Thes detectors are programmed to test every 24 hours, in addition to this the operators perform manual test weekly on the chlorine alarms to ensure a properly working detection system. CALL OUTS When a gas leak alarm occurs during the hours the plant is staffed, the plant operators will respond to the leak with three operators. The Chlorine Response Team can be dispatched to the plant during the staffed hours if the plant staff is unable to respond to the leak with a three person team. When Control receives a gas leak alarm after hours the Control Operator will call out the Chlorine Response Team and the sanitation standby operator. Upon arrival both will wait at the entrance gate for the other to arrive and will enter the plant together. RESPONSE TO MINOR LEAKS Two employees will respond with SCBA's, chlorine repair kit "B", gloves and a b ottle of 26 degree Baume Ammonia. The Third Person will also respond with a SCBA and stay near the truck radio. The First and Second Person will don their SCBAs, keeping each other in sight at all times. Using the ammonia they will locate the leak. Once the leak is located and is confirmed to be a system leak and not a vessel leak, the gas supply valve on the container can be shut off by turning the valve clockwise one full turn. When this has been done the Third Person will let control know whether repairs have been made or if further assistance is needed. RESPONSE TO MAJOR LEAKS Same as above except the response team will wear fully encapsulated suits if a severe gas leak has occurred or if the response team finds a vessel leak. The Third Person will notify control to send police and fire department personnel to the scene to secure and evacuate the surrounding area if necessary. The district's standby staff person and Training/Safety Specialist will be called as well. PLANNE D CHANGES TO FACILITY The chlorine system at this facility is under pressure, a system leak has the potential to allow several lbs of chemical to be released befor emergency response personnel are able to take the appropriate steps necessary to bring the leak to a stop. Plans are under way to change the presure system to a vacuum system which would automatically stop drawing chemicals from the containers if the process system is adversely effected. |