Eagle Rock Reservoir Outlet Chlorination Station - Executive Summary
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 DWP Eagle Rock Reservoir Outlet Chlorination Station chlorine handling process is subject to the U.S. Environmental Protection Agency (EPA) Risk Management Program and Plan and also to the California Accidental Release Prevention (CalARP) Program. These Programs require a summary in the Risk Management Plan (RMP) of poli |
cies 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 above information for the Eagle Rock Reservoir Outlet Chlorination Station 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 maintenanc
e 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 Eagle Rock Reservoir Outlet Chlorination Station has prepared an Emergency Response Plan for Hazardous Materials to facilitate coordination and emergency planning with offsite response 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 Eagle Rock Reservoir Outlet Chlorination Station has an
excellent record in preventing accidents from occurring.
General Facility and Regulated Substance Information
The Eagle Rock Reservoir Outlet Chlorination Station is located at 5403 Hillmont Avenue in Eagle Rock, next to the Ventura Freeway. This facility serves to chlorinate the reservoir, one inlet line, and two discharge lines. The water serves the northern and eastern Los Angeles area. The station consists of a chlorination room and a pump room. The facility currently stores chlorine, a regulated toxic substance under the EPA and CalARP Program rules. A maximum of seven one-ton chlorine containers is stored at the Eagle Rock Reservoir Outlet chlorine building. Six of these chlorine containers can be connected to the chlorination process to feed liquid and gaseous chlorine and one is stored as a spare. The one-ton container is the largest vessel (container) on line. The maximum quantity of chlorine present at the Eagle Rock Reservoir Outlet Chlorination Station at any given t
ime 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. However, the facility is normally unmanned and water treatment operators visit the facility daily and respond to any trouble alarms which may occur. Thus, the DWP Eagle Rock Reservoir Outlet facility is not subject to federal or California OSHA PSM regulations.
In normal operations, four chlorine 1-ton containers are manifolded together in two banks of two containers to supply chlorine. These four containers are equipped with Halogen actuators on the angle valves and will close the valves when a chlorine concentration of 10 ppm is detected in the room. The primary bank is connected to the liquid header and the secondary bank is connected to the gas header. The gas supplying containers bypass the evaporators, serving as an automatic backu
p when the primary containers run dry or the evaporator shuts down due to a low temperature condition. Connections are provided, without Halogen actuators, for two additional ton containers. These two containers have automatic shutoff valves in the piping system immediately downstream of the pigtail connections. Space is allocated in the room for the storage of one additional container that is not provided with a connection to the chlorination system.
The liquid chlorine passes from the containers to the evaporator where it is vaporized in a water bath. The gaseous chlorine then proceeds to one of the three chlorinators that regulate the flow of chlorine.
The gaseous chlorine is pulled by vacuum from the chlorinators to injectors where it is dissolved into mixing water to form a concentrated solution. For reservoir treatment, the injector is located on the shore next to the reservoir. For the two discharge lines, the injectors are located inside the chlorinators. The concen
trated solution is then piped into the reservoir through a diffuser, or into the discharge water through numerous diffusion points. The treated water is then piped into the distribution network.
Residual chlorine analyzers monitor residual chlorine in the pipeline downstream of the diffusers and provide feedback control for subsequent chlorine dosing. Dosing is also controlled in response to flowrate.
A chlorine leak detector with multiple sensors has been installed inside the building which alarms locally as well as at the Los Angeles Aqueduct Filtration Plant (LAAFP) at Sylmar.
In the event power is lost at the chlorine facilities, an alarm will alert the LAAFP control room. Loss of power will cause the emergency generator to take over powering station controls. Chlorine flow will continue unaffected, with no safety consequences.
The facility is normally unmanned; water treatment operators visit the facility daily. A response team coordinated from DWP Los Angeles Aqueduct
Filtration Plant (LAAFP) responds to any trouble alarms which may occur. Access to the facility is through gates, which are kept locked all the time.
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".
Atmospheric dispersion modeling has to be performed to determine the distance traveled by the chlorine released before its concentration decreases to the "toxic endpoint" selected by EPA of 3 ppm, which is the Emergency Response Planning Guideline Level 2 (ERPG-2). This is defined by the American Industrial Hygiene As
sociation (AIHA) as the "maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action." The residential population within a circle with a radius corresponding to the toxic endpoint distance has to be defined, "to estimate the population potentially affected".
The worst-case release scenario at the Eagle Rock Reservoir Outlet Chlorination Station involves a failure of the one-ton container and release of 2,000 pounds of chlorine to the atmosphere over a 10-minute duration, regardless of how improbable this may be. The chlorine release rate to the atmosphere was defined to be 200 lbs./min. No passive mitigation systems were considered in determining the chlorine release rate to the atmosphere.
EPA and CalARP regulations require that the models used for dispersion
analysis should appropriately account for the density of the released gas. Since the chlorine cloud formed during the worst-case release scenario would be denser-than-air, the Dense Gas Air Dispersion (DEGADIS 2.1) model was used for performing the air dispersion modeling analysis.
EPA-mandated meteorological conditions, namely Stability F, wind speed of 1.5 m/sec, highest daily maximum temperature (1130F), and average humidity (61%) were used for the dispersion modeling analysis. The results of the dispersion modeling analysis indicated that the worst-case 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 conta
inment 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 hazard review. A review of the past five-year accident history data for the chlorination facility pursuant to these rules indicated that there was one chlorine release, which resulted in offsite (outside the Eagle Rock Reservoir Outlet Chlorination Station boundary) toxic endpoint distances. The accident at this facility on October 21, 1997, resulted in the release of chlorine from the chlorinator vent, venting chlorine outside the building. However, this scenario was not selected as an alternative release scenario because the chlorinator vent now vents inside the building (it used to vent outside the building). The change would reduce the toxic endpoint distance for the chlorinator vent release scenario.
The scenario selected for the Eagle Rock Chlorinatio
n Station involves the release of liquid chlorine from a crack in one of the pigtails connecting the third container in a bank to the chlorination process. This container is not equipped with the Halogen actuator and a leak in the pigtail will allow the 1-ton containers to leak. This scenario can occur if the operator uses a pigtail, which is worn or has a defect, which results in a crack in the pigtail during the withdrawal of chlorine from the ton container. It is assumed that the crack developed in 1/4 inch diameter pigtail corresponds to a hole of 0.0625-inch (1/16-inch) diameter. The control room would have been warned of the chlorine leak by the chlorine monitors installed at the chlorination facility at a chlorine concentration of 1 ppm. At a concentration of 10 ppm, the Halogen actuators close the angle valves on the other four containers. It is assumed that approximately 60 minutes would be required for operators or an emergency response team to respond. One passive miti
gation system considered was the chlorination building structure that houses the one ton containers. Two active mitigation systems considered were the actuation of a chlorine detector and the actuation of the Halogen shut-off valves installed on the ton containers. The amount of chlorine released inside the building is 492 lbs, at an average rate over one hour of 8.2 lb/min.
The alternative release scenario toxic endpoint was also estimated using the Dense Gas Air Dispersion (DEGADIS 2.1) model. The toxic endpoint for chlorine is 3ppm. The results of the dispersion modeling analysis indicated that the alternative release scenario has offsite impacts. The typical meteorological conditions used were Stability D, wind speed 3.0 m/s, average air temperature of 630F, and 61% average humidity.
Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps
The DWP accidental release prevention program is based on the following key elements:
* Detailed mana
gement system and clear levels of responsibilities and team member roles.
* Comprehensive safety information that is readily available to staff, emergency responders, and contractors.
* Comprehensive preventive maintenance program.
* Performance of hazard review of equipment and procedures with operation and maintenance staff participation and review.
* Use of industry recommended 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 with remote monitoring, and the use of
Halogen actuators on the ton containers.
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 facility are on file at the facility. DWP also has procedures in place that are triggered to update safety information if there is a major change that makes existing information inaccurate.
In 1993, a detailed hazard review was conducted for the chlorination system equipment and procedures. The hazard review was further reviewed in A
pril 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 was developed in April 1999 to further improve the chlorine safety and staff is currently evaluating these recommendations. Staff will document the completion of the 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.
DWP has prepared written operating procedures for Eagle Rock Reservoir Outlet chlorination facility 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
* Normal Operations
* Shutdown, and
* Operating Problems and Remedies.
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.
ng is provided at least every three 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.
The 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-ne
eded basis. These allow the operator to rapidly review what maintenance is necessary, 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).
Internal Compliance Audits
The DWP will certify every three years (or earlier) that compliance with Program 2 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 Certific
ation Page and a Compliance Audit Checklist. The Compliance Audit Certification Page provides process identification, the dates of the audit, team members, 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.
The DWP incident investigation procedures describe incident r
eporting, 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
The Eagle Rock Reservoir Outlet Chlorination Station had one accidental release of chlorine in the past five years; the release quantity was estimated at five (5) pounds. Four onsite workers and one offsite person were exposed to chlorine and transported to a local hospital. These individuals were subsequently released. No evacuation or other offsite actions were necessary. A procedural change and two other improvements have made to prevent a future similar occurr
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
As part of the preparation of a Risk Management and Prevention Program (RMPP), a hazard review was performed in 1993 for the chlorination system. The hazard re
view was performed using the Hazard and Operability (HAZOP) technique and covered both equipment and procedures used for the chlorine handling system. A number of equipment and procedural changes were made as part of the implementation of the recommended actions. All the above recommendations have been evaluated by the DWP. In addition, a pressurized liquid chlorine system has been added and four Halogen actuators are mounted on the ton containers. Additional 20 changes to further improve chlorine safety were identified in April 1999, when the hazard review was completed for the facility. It is expected that these recommendations will be evaluated by December 1999. The implementation of these recommendations will further improve the safety of the chlorination system.