Los Angeles Aqueduct Filtration Plant - Executive Summary

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Chlorine is the most commonly used substance for disinfecting drinking water.  The addition of chlorine or chlorine compounds to water is called chlorination.  Chlorination is considered to be the most important process for preventing the spread of waterborne disease in drinking water.  The Los Angeles Department of Water and Power (DWP) also uses chlorine for drinking water disinfection purposes to protect public health per state and federal water quality standards.  Storing and handling large quantities of chlorine can create hazardous situations.  DWP takes safety obligations in storing and using chlorine as seriously as it takes providing safe drinking water.  The LAAFP facilities chlorine handling processes are subject to the U.S. Environmental Protection Agency (EPA) Risk Management Program Rule and also to the California Accidental Release Prevention (CalARP) Program regulation. Both of these regulations require submission of a Risk Management Plan (RMP).  An integral part of th 
eRMP is a summary of policies and procedures followed to safely operate the facility, including a description of the possible consequences in case of an accident and the actions which will be taken by the facility in an event of an emergency. 
 
The following information is specifically required in the RMP Executive Summary:  
 
* Accidental release prevention and emergency response policies. 
 
* General facility and regulated substances information. 
 
* Offsite consequence analysis results. 
 
* Summary of the accidental release prevention program and chemical-specific prevention steps. 
 
* Five-year accident history summary. 
 
* Emergency response program summary. 
 
* Planned changes to improve safety. 
 
The DWP Los Angeles Aqueduct Filtration Plant (LAAFP) facilities consist of two different chlorination stations and one chemical depot; the LAAFP facility, the Los Angeles Reservoir Outlet Chlorination Station, and the Van Norman Chemical Depot. The above information for the three DWP Los Angele 
s Aqueduct Filtration Plant facilities is provided below. 
 
Accidental Release Prevention and Emergency Response Policies 
 
The DWP accidental release prevention policy involves a unified approach that integrates the use of proven technology, trains staff in operation and maintenance practices, and uses tested and proven management system practices.  All applicable requirements of the State of California and EPA's Prevention Program are adhered to, including key elements such as training, systems management, and emergency response procedures.   
 
The DWP emergency response policy involves the preparation of emergency response plans for hazardous materials which are tailored to each facility and to the emergency response services available in the community, and is in compliance with the EPA and CalARP Program Emergency Response Program Requirements.  The LAAFP has prepared an Emergency Response Plan for Hazardous Materials to facilitate coordination and emergency planning with offsite resp 
onse officials and facilities in the event of an emergency.  The emergency response plan has been coordinated with local response agencies (City of Los Angeles Fire Department).  The LAAFP has an excellent record in preventing accidents from occurring. 
 
General Facility and Regulated Substance Information 
 
The three LAAFP facilities are located in the same complex adjacent to the Los Angeles Reservoir in Sylmar, California.  The Los Angeles Aqueduct Filtration Plant treats up to 600 million gallons per day of water from the Los Angeles Owens River Aqueduct or from the Metropolitan Water District. Liquid chlorine is delivered to the plant in 90-ton railcars or by truck in one-ton containers. The 90-ton railcar is the largest vessel (container) on line. LAAFP can store a maximum of 6 railcars and 28 one-ton containers.  
 
The Los Angeles Reservoir Outlet Chlorination Station serves to chlorinate water in a single 120" diameter pipeline exiting the reservoir.  The treated water is then pip 
ed into the distribution network which serves much of the San Fernando Valley with potable water and feeds other reservoirs.  It also chlorinates the outlet flow from the Van Norman Bypass Reservoir and another pipeline called the Rinaldi Trunk Line.  This station stores chlorine in a 25-ton bulk storage tank; it can also store up to 12 one-ton chlorine containers to be used when the bulk tank is taken out of service for maintenance or repair. The 25-ton bulk tank is the largest vessel (container) on line.  
 
The Van Norman Chemical Depot is used for storage of up to 100 unopened one-ton chlorine containers and up to 40 150-lb cylinders in addition to various other chemicals.   The one-ton container is the largest vessel (container) on-site.  The depot is equipped with a one-ton capacity dry medium chlorine scrubber which is activated in the event of a chlorine leak.  
 
All three LAAFP facilities currently store and/or use chlorine, a regulated toxic substance under the EPA and CalARP Pr 
ogram rules.  The maximum quantity of chlorine present at the LAAFP facilities at any given time exceeds the listed threshold quantities in the EPA and CalARP rules. It also exceeds the listed threshold quantities in the federal and California Occupational Safety and Health Administration (OSHA) Process Safety Management (PSM) Standards. Additional details of the three facilities are provided below. 
 
The Los Angeles Aqueduct Filtration Plant 
 
Liquid chlorine is supplied to the Los Angeles Aqueduct Filtration Plant in 90-ton railcars with a backup of one-ton containers for the chlorination process.  A maximum of three railcars or four one-ton containers can be connected to the chlorination process at any given time.  Liquid or gaseous chlorine is withdrawn from the railcars. Midland valve actuators are connected to both the liquid and gas connections on the railcars.  The Midland valve actuators will close on the railcar and stop the flow of chlorine when 10 ppm of chlorine is detected  
in the area.  Additionally, the detection of 10 ppm chlorine will automatically close the ball valves connecting the hard piping to the flex hoses stopping the possible backflow of chlorine, in case a crack developed in the flex hose.  
 
Liquid chlorine travels under pressure to any of the six evaporator units, while gaseous chlorine can be withdrawn directly to the chlorinators.  The evaporators vaporize the liquid in a water bath to form a superheated gas which passes through a pressure-reducing valve to the chlorinators.  The chlorinators regulate the gas flow and discharge it to the injection lines at the appropriate rate.  Chlorine gas from the chlorinators is pulled by vacuum to injectors located on the downstream piping at various chlorine application points. 
 
Four chlorine leak detectors continuously monitor the railcar area, ton container storage area, chlorine pipe trench, and the chlorination room in the existing system.  The alarms are annunciated at the chlorine control pan 
el in an adjacent room to the chlorination room, as well as at the operator's console in the control room.  
 
The LAAFP control room at the plant is manned 24 hours a day, year round.  Access to the plant is through security gates, which are kept locked all the time. 
 
The Los Angeles Reservoir Outlet Chlorination Station 
 
At the Los Angeles Reservoir Outlet Chlorination Station the primary supply of liquid chlorine is from a bulk tank.  A gas line is also connected to the bulk tank to serve as a backup supply if the liquid supply is disabled.  Additionally, up to 4 one-ton containers can be connected to liquid or gas feed headers in the event the bulk tank is taken out of service for maintenance.  Midland valve actuators are connected to both the liquid and gas connections on the bulk tank.  The Midland valve actuators will close on the bulk container when two of the chlorine sensors detect 10 ppm of chlorine in the chlorine storage room.  
 
Liquid chlorine is normally withdrawn from the 
bulk tank to a piping header that leads to either one of the two evaporators.  The gas discharge piping from the evaporators supply pressurized chlorine gas to the chlorinators through regulating valves.  A gas header from the bulk tank serves as a backup supply and automatically takes over when the evaporator is shut off due to a low temperature condition.  The bank of 4 one-ton containers can also feed liquid or gas through the header system to the evaporators or chlorinators. 
 
There are a total of seven chlorine injectors located in the three injection vaults.  The injectors provide vacuum which draws chlorine gas from the chlorinators into mixing water to form a concentrated solution.  The solution is piped through diffusers into the various water pipelines.   
 
A chlorine leak detector is provided to detect chlorine leaks in the chlorinator and chlorine storage rooms.  The detector signals an alarm by activating (1) a flashing red light over the entry door to the building, (2) an  
audible alarm within the chlorination building, and (3) an alarm at the Los Angeles Aqueduct Filtration Plant Control Room. 
 
In the event power is lost at the Los Angeles Reservoir Outlet facility, an alarm will alert the control room.  Loss of power will cause the backup generator to take over powering the entire station.  Chlorine flow will continue unaffected, with no safety consequences. 
 
The Van Norman Chemical Depot 
 
The Van Norman Chemical Depot is a structure used for the storage of various chemicals used by DWP.  The Depot includes a 52'-8" x 101'-4" chlorine container storage room for receipt, storage and distribution of up to 100 unopened chlorine one-ton containers and up to 40 150-lb cylinders. There are no chlorination processes at the facility. 
 
The Depot is equipped with chlorine leak detectors and a one-ton capacity dry medium chlorine scrubber, which is activated automatically in the event of a chlorine leak inside the Depot. Containers and cylinders are moved in, out 
, and around the building using a monorail system; thus, reducing the probability of accidents involving chlorine cylinders and containers. Additionally, all containers in the Depot are stored with their protective domes on, for safety. 
 
Offsite Consequence Analysis Results 
 
The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worst-case release scenario" and "alternative release scenario". The first scenario is defined by EPA, which states that "the owner or operator shall assume that the ... maximum quantity in the largest vessel ... is released as a gas over 10-minutes," due to an unspecified failure. The alternative scenario is defined as "more likely to occur than the worst-case release scenario". 
 
The worst-case release scenario at the LAAFP facilities involves a failure of the 90-ton railcar and release of 180,000 pounds of chlorine, the largest vessel on-site, to the atmosphere over a 10-minute duration, regardless of how imp 
robable this may be.  The chlorine release rate to the atmosphere was defined to be 18,000 lbs./min. No passive mitigation systems were considered in determining the chlorine release rate to the atmosphere. 
 
The released liquid chlorine is assumed to form a denser-than-air cloud consisting of chlorine vapor and liquid droplets (aerosols) and then disperse in the atmosphere. The distance to the toxic endpoint was estimated using the Dense Gas Air Dispersion (DEGADIS 2.1) model.  The toxic endpoint selected by EPA and CalARP rules for chlorine is 3 ppm, which is the Emergency Response Planning Guideline Level 2 (ERPG-2).  The toxic endpoint was conservatively set by EPA to ensure public notification and that local emergency response planning takes into account the greatest possible impacted area surrounding the release point.  
 
EPA-mandated meteorological conditions, namely atmospheric Stability Class F, wind speed of 1.5 meter per second, highest daily maximum temperature (113 deg F), a 
nd average relative humidity (63%) were used for the worst-case release scenario analysis.  The results of the dispersion analysis indicated that the worst-case release scenario has offsite impacts. 
 
RMP and CalARP rules require that a scenario which results in offsite toxic endpoint distance and is more likely to occur than the worst-case scenario should be selected as the alternative release scenario, unless no such scenario exists.  Unlike the worst-case scenario, the alternative release scenario may consider "active" mitigation such as automatic shutoff valves, excess flow valves, and containment with scrubbers.  Active mitigation is defined as requiring mechanical, electrical, or human input. 
 
The alternative release scenarios must consider the facility accident history and/or failure scenarios identified in the process hazard analysis.  A review of the past five-year accident history data for the chlorination facility pursuant to these rules indicated that there were no chlorine  
releases, which could have resulted in offsite (outside the LAAFP boundary) toxic endpoint distances.  
 
Since the LAAFP facility consists of three different chlorination processes, including two chlorination systems and a storage depot, several alternative release scenarios were considered.  All accidental releases of chlorine from the chemical depot would be mitigated by a scrubber and the toxic endpoint distance would not extend off-site.  The alternative scenario considered for the filtration plant was an event that occurred at the facility and involves a leaking railcar pressure safety valve.  A screening analysis was performed for this scenario and it was found that the toxic endpoint distance would not extend offsite for this scenario.  The final scenario evaluated was for the Los Angeles Reservoir Outlet chlorination station, which indicated that a toxic endpoint distance would extend offsite. 
 
The alternative release scenario selected involves the release of chlorine from the f 
lex hose connecting the bulk tank at the Los Angeles Reservoir Outlet Chlorination Station to the chlorination process.  This scenario can occur if a flex hose is worn or has a defect and results in a crack in the flex hose during the withdrawal of chlorine from the chlorine bulk tank.  It is assumed that the crack developed in the flex hose (diameter 1-inch) corresponds to a hole of 0.1875-inch (3/16 inch) diameter.  The Midland valve actuators would close on the bulk tank when the chlorine detectors detect a chlorine concentration of 10 ppm. The only chlorine that would leak from the crack would be the liquid in the 80 feet of 1-inch pipeline plus the 100 pounds of chlorine in the evaporator reservoir. The control room would have been warned of the chlorine leak by the chlorine monitors installed at the chlorination facility.  It is assumed that approximately thirty minutes would be required for operators or an emergency response team to respond. One passive mitigation system conside 
red was the chlorination building structure that houses the chlorination building. Two active mitigation systems considered were the actuation of chlorine detectors and the activation of the Midland valve actuators on the bulk tank.  The amount of chlorine released inside the building was estimated at 139 lbs, at an average rate of 74.6 lbs/min for 111 seconds. 
 
The release rate reduction from the enclosed building is estimated to be approximately 92% of the release rate from the cracked flex hose, per guidance from EPA regarding control efficiency levels for buildings storing chlorine.  The release rate for chlorine was thus estimated at 6 lbs./min. 
 
It may be noted that the occurrence of this scenario is highly unlikely because the flex hose is on the DWP preventive maintenance schedule. In addition, the flex hose is visually inspected during daily operator rounds.  
 
The alternative release scenario toxic endpoint distance was also estimated using the Dense Gas Air Dispersion (DEGADI 
S 2.1) model.  The toxic endpoint for chlorine is 3 ppm. As suggested by EPA, typical meteorological conditions of Stability D, wind speed 3.0 m/s, average air temperature of 64 0F, and 63% average humidity were used for the dispersion analysis.  The results of the dispersion analysis indicated that the toxic endpoint distance extends offsite but has no discernable offsite impacts. 
 
Finally, no chlorine releases that could have caused safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at the LAAFP facilities during the last five years.  
 
Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps 
 
The DWP is in compliance with Federal and State Process Safety Management requirements. The DWP accidental release prevention program is based on the following key elements: 
 
* Detailed management system and clear levels of responsibilities and team member roles. 
 
* Comprehensive process 
safety information that is readily available to staff, emergency responders, and contractors. 
 
* Comprehensive preventive maintenance program. 
 
* Performance of process hazard analysis of equipment and procedures with operation and maintenance staff participation and review. 
 
* Use of state-of-the-art process and safety equipment. 
 
* Use of accurate and effective operating procedures, written with the participation of the operators. 
 
* High level of training of the operators and maintenance staff. 
 
* Implementation of an incident investigation, inspection, and auditing program using qualified staff. 
 
Chemical-specific prevention steps include availability of self-contained breathing apparatus (SCBA), worn by the operators during connection/disconnection of chlorine supply, awareness of the hazardous and toxic properties of chlorine, presence of chlorine detectors and alarms with remote monitoring, the use of Midland valve actuators, and the operation of a scrubber. 
 
Process and Chemic 
al Safety Information 
 
Comprehensive chemical data has been assembled to include regulatory reporting and action thresholds, health hazard, and chemical exposure limitations, as well as detailed physical properties of chlorine.  This information includes chlorine background information and MSDS sheets. 
 
Equipment safety information was compiled on the chlorine process. Specifications for the chlorine process are collected and provided in one place for easy reference. Details such as maximum intended inventory; safe upper and lower temperatures; and safe upper and lower pressures for the chlorination facilities are on file at the facility.  DWP also has procedures in place that are triggered to update process safety information if there is a major change that makes existing information inaccurate. 
 
Process Hazard Analysis  
 
In 1994 and 1995, detailed process hazard analysis (PHA) were conducted for the two chlorination facilities and storage depot.  The PHAs were further reviewed in Apr 
il 1999 and will be updated again within a five-year period or whenever there is major change in the process.  A list of recommended actions were developed in April 1999 to further improve the chlorine safety and staff is currently evaluating these recommendations.  Staff will document the completion of recommended actions. 
 
A seismic walkthrough was recently completed based on the 1997 UBC LEPC Region 1 guidance document, and recommendations were provided to DWP staff for their evaluation and implementation.  
 
Operating Procedures 
 
DWP has prepared written operating procedures for LAAFP facilities that provide clear instructions or steps for safely conducting activities relating to chlorination process. They are consistent with the chlorine safety information.   Written operating procedures included in the facility's Operation and Maintenance Manual for Chlorination Stations include: 
 
* Delivery of Chemicals 
 
* Container Connections 
 
* Pre-Start 
 
* Start 
 
* Normal Operations 
 
* Shutdo 
wn, and 
 
* Operating Problems and Remedies. 
 
Training  
 
The DWP ensures that each employee operating or maintaining the chlorination process, and each employee newly assigned to this process, is trained and tested for competency in the operating procedures listed above.  The DWP employee training documentation files include training records for each employee assigned to operate or maintain the chlorination process.  The training ensures that the employee has the required knowledge, skills, and abilities to safely carry out the duties and responsibilities, including chlorine emergency response, as provided in the operating procedures.  Employee training includes as a minimum the following elements: 
 
* Safety Information; 
 
* Process Technology and Process Equipment, including safety systems; 
 
* Maintenance Procedures; 
 
* Operating Procedures for the chlorine system; 
 
* RMP Program contents; and 
 
* Emergency Response Plan and Procedures. 
 
Refresher training is provided at least every thre 
e years to each employee operating the chlorination process to ensure that the employee understands and adheres to the current operating procedures.  In addition, DWP ensures that operators are trained in any updated or new procedures prior to startup of a process after major modifications. 
 
Contractors 
 
DWP Contractor procedures specify the information required to be provided to the contractors performing work on or near the chlorination processes, the training requirements for contractor employees, and mechanism to obtain assurance from contractors that they have informed their employees of the appropriate safety rules.  DWP is required to provide information and explanations concerning the hazards and processes and obtain and evaluate information regarding the contractors safety program.  
 
Pre-Startup Safety Review and Mechanical Integrity Program 
 
DWP has procedures in place to ensure that a pre-startup safety review is conducted prior to starting a new covered process or prior to  
making modifications to the chlorination systems that require a MOC procedure implementation.  The required conditions prior to startup include: 
 
* Construction and/or equipment are in accordance with design specifications; 
 
* Safety, operating, maintenance, and emergency procedures are in place and are adequate; 
 
* A PHA has been performed for any new facilities and recommendations have been resolved or implemented prior to startup; 
 
* At modified facilities, MOC requirements have been met; and 
 
* Training of each operating and maintenance employee involved in the process is complete. 
 
These procedures ensure that no new/significantly modified process will start-up and no regulated substances will be introduced into such a process prior to the pre-startup safety review.  This constitutes a final check that the process and equipment are ready to go and that the recommendations of the PHA have been implemented or adequately addressed.  This will ensure that the design and construction o 
f a new or modified process is safely executed and that the facility is prepared to operate it.  
 
Mechanical integrity procedures for the plant ensure that written maintenance procedures are implemented and documented, including training of maintenance personnel. 
 
DWP operates a Mainsaver Program that generates a task order for performance of the preventive maintenance routine after a designated time past the closing of the previous task order for that maintenance.  Description of the work to be performed is included with the printed work order.  The water treatment supervisor is responsible for this task. 
 
In addition, the written maintenance procedure is provided in the General Operation and Maintenance Manual as follows: Preventive maintenance checklists are provided which summarize inspection, test, and maintenance schedules on a daily, weekly, monthly, biannual, annual, every 2 to 10 years, and as-needed basis.  These allow the operator to rapidly review what maintenance is necess 
ary, and provide supervisors with a brief log of maintenance history at the chlorination station.  The schedules are supplemental to the log sheets on-site and provide a summary and quick reference to manufacturer's O&M manuals.  
 
DWP documents inspection, testing, and maintenance of chlorination equipment and assures the performance is done in accordance with the recommendations of the manufacturer and industry groups (i.e., Chlorine Institute). 
 
Hot Work Permits and Management of Change  
 
Hot work refers to work involving electric or gas welding, cutting, brazing, or similar flame or spark producing operations.  The procedures call for the issuance of a hot work permit whenever it is conducted on or near the chlorination processes and other areas deemed appropriate as described in the procedures.  Fire prevention and protection systems are in place prior to the issuance of the hot work permit.  The permit indicates the dates the work is authorized for, the location and specific opera 
tional requirements and is kept on file in the administrative office.  
 
DWP Management of Change (MOC) procedures include steps required to be taken by plant personnel prior to implementing changes to chlorination equipment, procedures, raw materials, and processing conditions.  Training, PSI, operating procedures, and maintenance procedures are updated according to the changes made. 
 
Internal Compliance Audits 
 
DWP will certify every three years (or earlier) that compliance with Program 3 Prevention Program requirements are met and that procedures and practices developed are adequate and being followed. 
 
The compliance audit will consist of separating the RMP program elements or sections, and auditing each element to determine compliance and effectiveness.  For each internal audit, the audit team will complete a Compliance Audit Certification Page and a Compliance Audit Checklist.  The Compliance Audit Certification Page provides process identification, the dates of the audit, team me 
mbers, and certification by the audit leader and the Plant Manager.  The Compliance Audit Checklist details the requirements of each RMP element and contains questions that may assist with the auditing process. The audit checklist for each element consists of the following three sections: 
 
* Records Review: A review of the RMP written Prevention Program. 
 
* On-Site Conditions: The audit team will review the program elements based on observation of the plant conditions and safety practices. 
 
* Interviews:  The program elements will be evaluated by interviewing personnel from appropriate functions including operations, maintenance, management, and contractors. 
 
Team members will record RMP program deficiencies identified during the audit on the checklist.   
 
Incident Investigation 
 
The DWP incident investigation procedures describe incident reporting, investigation, and investigation reporting steps to be followed by plant personnel.  The incident investigation shall be started promptly  
but no later than 48 hours after the event.  The DWP will promptly address and resolve all recommendations and shall implement the recommendations in a timely manner to prevent an incident recurrence.  All incident investigation reports will be retained on DWP file for at least a period of five years from the date the reports are completed. 
 
Five-year Accident History Summary 
 
No chlorine releases that could have caused safety or health hazard (deaths, injuries, property or environmental damage, evacuations, or sheltering in place) occurred at the LAAFP facilities during the last five years. 
 
Emergency Response Program Summary 
 
DWP is a first responder, its employees respond to chlorine accidental releases.  Depending on the severity of the accidental release, external resources such as the City of Los Angeles Fire Department may be solicited to aid in handling a chlorine release.   
 
As part of the emergency response program, the DWP has developed and implemented an emergency response  
plan for the purpose of protecting public health and the environment. The following elements are included: 
 
(a) An emergency response plan, maintained at the stationary source and at the Los Angeles Aqueduct Filtration Plant (LAAFP) containing: 
 
* Organizational structure (chain-of-command) and responsibilities of various DWP personnel. 
 
* Procedures for planning and coordination with off-site emergency response organizations. 
 
* Details of the training programs for all employees involved with the chlorination process, contractor training, and medical surveillance of DWP personnel who respond to chlorine releases. 
 
* Details of emergency recognition and prevention at the DWP. 
 
* Procedures for informing the public and local emergency response agencies about accidental releases. 
 
* Documentation of proper first aid and emergency medical treatment necessary to treat accidental human exposures and the detailed information on emergency health care. 
 
* Procedures and measures for emergency  
response after an accidental release. 
 
(b) Procedures for the use of emergency response equipment and for its inspection, testing, and maintenance.  
 
(c)Training in relevant procedures for all employees involved with the chlorination process. 
 
(d) Procedures to review and update, as appropriate, the emergency response plan to reflect changes and ensure that employees are informed of changes. 
 
Planned Changes to Improve Safety 
 
Numerous changes to improve safety (recommended actions) were previously identified in 1994 and 1995 for the chlorination systems and chlorine storage depot, when California Risk Management and Prevention Program (RMPP) and Process Safety Management (PSM) Program preparations were made for the facility. All the above recommendations have been evaluated and implemented by the DWP.  Additional 12 changes to further improve chlorine safety were identified in April 1999, when the process hazard analysis was reviewed for the facilities. It is expected that these recom 
mendations will be evaluated by December 1999.  The implementation of these recommendations will further improve the safety of the chlorination and storage facilities.
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