Dyer Road Wellfield Primary Disinfection Facility - Executive Summary |
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RISK MANAGEMENT PLAN - PRIMARY DISINFECTION FACILITY, DYER ROAD WELLFIELDS EXECUTIVE SUMMARY Irvine Ranch Water District (IRWD) has established a risk management plan according to EPA's regulations (40 CFR Part 68) to enhance already existing safety and emergency response programs. IRWD is extremely cautious in the handling of all chemicals and is very diligent about safety for its employees and its communities. IRWD 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 IRWD has an emergency response plan in effect to handle potential emergency situations at this facility. This plan was designed to meet the following objectives: 1.) To save lives. 2.) To minimize and avoid injuries. 3.) To protec t the environment. 4.) To minimize property damage. Key elements of the Emergency Response Plan include: - A detailed Emergency Response Action Guide - Key phone numbers and contact points for the IRWD Emergency Response Team - Incident Command System (ICS) w/Unified Command interface - ICS position descriptions w/responsibilities - Vicinity and evacuation maps - Detailed task-by-task plans for: - Evacuation - Fire in a Process or Non-Process Area - Injuries - Threats/Civil Disorder - Wildland or Adjacent Property Fire - External Events (e.g., seismic) - Potential Imminent Danger to Personnel - Chemical Spill (e.g., caustic, aqueous ammonia) - Chlorine Release - Off-Site Event Involving a Hazardous Material IRWD maintains a safety committee whose members are the designated emergency coordinators for the facility. IRWD has 26 employees that are specialists, trained and fully equipped to handle hazardous spill containment and cl eanup. These employees train monthly and run drills twice a year. The Emergency Response 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. This Plan has been reviewed and updated to ensure compliance with the PSM, RMP, and CalARP regulations Stationary Sources and Regulated Substances Chlorination System The chlorine system at Irvine Ranch Water District's Primary Disinfection Facility (PDF) is used for the treatment of water at the Dyer Road Well Field pipeline. Chlorine is stored in one-ton containers (21) in the chlorine storage room. Chlorine gas leaving the one ton containers passes through a vacuum regulator to the chlorine feeders. Still under vacuum from the feeders, it is drawn to injectors and mixed with water from th e wells. The chlorine solution is delivered back into the pipeline. The chlorine storage room has two independent manifold systems connected to a common header that feed into the chlorine system. Five chlorine containers are connected to each manifold system. One manifold is active and the other is kept in stand-by status. Chlorine tanks are replaced in-groups of five when one side of the distribution system becomes empty. Irvine Ranch Water District operators use a monorail hoist to do this replacement. Each one ton container is placed on a scale to allow Irvine Ranch Water District operators to plan ahead for ordering more chlorine and for the change out procedure. Each container is positioned so that the valves are vertically aligned. A vacuum regulator is connected to the top valve of each one ton container to ensure that chlorine gas is drawn out of the container. A vacuum is created when process water is pumped through the injectors. This flow generates a vacuum (appro ximately 1-3 in. Hg) which opens the vacuum regulator. Upon loss of vacuum in the line from any one ton container, a diaphragm in the vacuum regulator will close, stopping any chlorine from escaping. Any chlorine in the piping upon loss of vacuum will be drawn through the chlorine feeders and into solution. The maximum quantity of chlorine that can be stored on site is 42,000 pounds. Aqueous Ammonia System The aqueous ammonia process at PDF consists of pumping a 29.4 percent concentration solution from the two storage vessels directly into the pipeline. The ammonia solution is delivered through use of metering pumps. Four pumps are present in the ammonia storage room where two pumps remain on and the other two are spares. Aqueous ammonia at 29.4 percent concentration is contained in two storage vessels in the ammonia storage room. It is drawn directly from the bulk storage tanks by chemical metering pumps and fed into the water pipeline. There are two high range and two low ra nge metering pumps located in the ammonia storage room. Under normal conditions, either one high range or one low range pump will be in operation with the other compatible pump serving as standby. A maximum of two 1,500-gallon capacity vessels is maintained in the ammonia storage area. Hazard Assessment Summary Worst Case Release Result Summary Scenario Description: Release of the maximum quantity of chlorine that can be stored in the largest vessel - 2,000 pounds in 10 minutes. The container is located in a building; therefore, this passive mitigation measure was incorporated in the calculations. The most pessimistic meteorological conditions were used as specified in the regulation. The reference table included in EPA's RMP Guidance for Wastewater Treatment Plants was used to determine the maximum downwind distance to 3 ppm. The result shows that offsite areas may be affected. Alternative Release - Chlorine Scenario Description: A release of chlorine gas from 1/4-inch diam eter leak until the container is empty (2,000 pounds). The containers are stored inside a building equipped with a scrubber, which will automatically start in the event a chlorine leak is detected by the sensor. However, when these active and passive mitigation measures were incorporated the release is completely mitigated, consequently, the release rate after these measures were incorporated was too small to measure. The meteorological conditions specified in the regulation for alternative scenarios were used. The reference table included in EPA's RMP Guidance for Wastewater Treatment Plants was used to determine the maximum downwind distance to 3 ppm. The downwind distance for this scenario is significantly less than that for the worst case scenario. However, in this case also offsite areas may be affected. Alternative Release - Aqueous Ammonia Scenario Description: The alternative release scenario is a liquid release that forms a pool. This scenario assumes that the release is from a 1 inch hole in the pipeline, downstream of the emergency shut down valve. It is assumed that the ammonia sensor will activate an alarm to notify operators. The meteorological conditions specified in the regulation for alternative scenarios were used. The reference table included in EPA's RMP Guidance for Wastewater Treatment Plants was used to determine the downwind distance to 200 ppm ammonia concentration. The downwind distance for this scenario is about the same as that obtained for the alternative release scenario for chlorine. Accidental Release Prevention Program and Chemical-Specific Prevention Steps IRWD has a Process Safety Management program in place to manage the handling of chlorine and aqueous ammonia. In addition, common industry standards, policies, and procedures are utilized to ensure safe practices are being performed. This includes 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 (4 total). In the event of a chlorine gas leak reaching 0.5 ppm, the detectors relay a signal that activates a horn and a light outside the room where chlorine has been detected. In addition, the alarm is displayed on the SCADA monitors. Finally, at 1 ppm, the alarm signal is routed to the phone dialer system, WIN 911, where the pagers are alarmed Five Year Accident History There have been no reportable releases of chlorine at the facility since its inception in 1997. Planned Changes to Improve Safety Several studies have been conducted recently to examine mitigation measures to improve safety at the Irvine Ranch Water District Primary Disinfection Facility. These studies include the following: Process Hazard Analysis, Seismic Assessment, Hazard Assessment, and PSM Compliance Audit. The recommendations from these studies will be completed by June 11, 1999. Some of the recommendations are listed below. 1. Arrange emerg ency procedures with the Fire Department. 2. Verify that a procedure is written that describes container installation. 3. Implement manufacturer's recommendations regarding scheduled maintenance for the chlorine switches and alarms. 4. Develop a routine work requirement in the Computer Maintenance Management System (CMMS) to replace the split tubing (pigtails) on the chlorine system annually during the off season. 5. Correct signs on entry doors near alarm lights so that the sign reflects status of yellow and red lights. 6. Verify the exit of the chlorine storage room floor drain and post signs indicating this location. 7. Consider relocating the hoses in the caustic scrubber room closer to the doorway and have the hose pre-connected to the pump, ready for use. 8. Once operating procedures are complete, ensure that operators/employees who operate/maintain the system have access to the procedures. Consider having procedures posted at the facility. Build checklist from pr ocedures. 9. Ensure that the operating procedures are reviewed and certified at least annually or sooner if necessary. 10. Install a chlorine sensor interlocked to the SCADA system in the respective injection vault to ensure early detection of a leak. 11. Consider adding a monthly or quarterly visual inspection of each vault in the Mechanical Integrity program to ensure that all equipment is working properly. 12. Add the inspection/testing requirements for the new chlorine sensors to the Mechanical Integrity program. 13. Ensure that the Quality Assurance procedure included in the Mechanical Integrity program (Item 6) is followed by all IRWD personnel and contractors to ensure that compatible materials are used in the future. |