Westlake Water Filtration Plant - Executive Summary

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Chemicals are widely used in industry, in the home, in the environment.  They are transported on roads, water, and railways.  The Westlake Filtration Plant (Westlake FP) uses chemicals, as a necessary part of providing safe drinking water.  Chlorine is used to disinfect water to insure safety to customers.  Storing large qualities of chlorine can be a hazard.  As the agency responsible for operating Westlake FP, Las Virgenes Municipal Water District (LVMWD) takes our safety obligations in storing and using these chemicals as seriously as we take providing the public safe drinking water.  The following document describes what might happen in the unlikely event of an accident involving chemicals at Westlake FP, the steps taken every day to ensure safety, and what to do in event of an emergency.  For questions or concerns, please contact Brian Whitaker/Principal Engineer at 818/251-2158. 
Accidental Release Prevention and Emergency Response Policies 
LVMWD's accidental relea 
se prevention policy involves a unified approach that integrates proven technology, staff fully trained in safe operation and maintenance practices, and tested management system practices.  All applicable procedures of the State of California and U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to, including key elements such as training, systems management, and emergency response procedures.   
This document complies with the EPA Risk Management Program, under Section 112 (r) of the Clean Air Act (CAA) Amendments of 1990, 40 Code of Federal Regulations (CFR) Part 68 and the California Accidental Release Prevention (CalARP) Program under California Code of Regulations (CCR) Title 19, Division 2, Chapter 4.5.   These regulations require facilities storing large quantities of certain chemicals like chlorine to prepare a Risk Management Plan (RMP).  The Westlake FP has a chlorination system that uses chlorine gas fed from liquid chlorine containers.  This document 
summarizes LVMWD's existing health and safety programs, internal response, policies, procedures, and ongoing actions that are designed to prevent or minimize impacts of any accidental releases of chlorine to the environment.  LVMWD has prepared an emergency action plan to handle any potential accidental releases.  To date, LVMWD and Westlake FP  have an excellent record in preventing accidents from occurring. 
General Facility and Regulated Substances Information 
The Las Virgenes Municipal Water District provides potable water, recycled water and sanitation services to more than 60,000 people across a 122 square mile area of western Los Angeles County.  The District's service area includes the cities of Agoura Hills, Calabasas, Hidden Hills, Westlake Village, and several nearby, unincorporated areas.   
Westlake FP is a water treatment plant located at 32601 Torchwood Place in Westlake Village, California in Los Angeles County.  Westlake FP consists of a 9,800 acre-foot potable water 
open storage reservoir, a 15 million gallon per day (MGD) diatomaceous earth (DE) filtration plant and a pumping station.  The facilities are used alternately to store imported water and to withdraw and treat it for customer use.  The chlorination facilities are therefore in active operation for approximately 6 months a year (typically in the summer) and inactive during the other 6 months.  During the inactive periods, chlorine is limited to the storage containers (not pipelines or equipment).  The facilities, including the surrounding reservoir watershed, encompass approximately 500 acres.  The filtration plant and pump station are located on two of these acres in the City of Westlake Village.  The facilities are about 2 miles south of the 101 (Ventura) Freeway, adjacent to in the Three Springs housing development.  The pump station is located at the base of Westlake Dam near the Three Springs Park, off Three Springs Drive.  The filtration plant is located at the top of Westlake Dam  
at the end of Torchwood Place 
Westlake FP currently stores chlorine at the pump station.  Chlorine is a regulated toxic substance under federal RMP and CalARP regulations.  Chlorine at Westlake FP is stored in four 1-ton cylindrical storage containers.   Facilities storing more than 2,500 pounds of chlorine are required to prepare a RMP in accordance with federal RMP and CalARP regulations. 
Liquid chlorine is brought to the plant in high strength steel containers.  Gaseous chlorine is withdrawn entirely under vacuum from the containers during use.  In the unlikely event of a break in the chlorine piping, the vacuum regulator would automatically close, shutting the process down.   
The chlorine process is checked twice during the daily 9-hour shift during active operation as part of the normal rounds at this facility. The chlorine storage is checked at least daily during non-active periods.  Chlorine detectors monitor continuously for leaks in the storage room and the equipment room a 
t the pump station and filter buildings.  Should a leak be detected, an emergency scrubbing system would automatically activate to fully neutralize any chlorine released within the storage room, protecting employees and the public from any chlorine hazard.  
Westlake FP is also equipped with a number of alarm systems.  Should a leak be detected, leak detectors at the pump station or filter building would activate red warning lights on the building exteriors and an audible alarm would sound.  An alarm is also generated on the plant computer control system that sends an alarm via the phone system to contact operators via pagers during off-shift hours.  The leak detector at the pump station is also remotely monitored via telemetry at District headquarters.  If the leak detector should detect chlorine at concentration of 1 ppm or above, the central computer would shut down the pumps and the emergency scrubber system will be automatically activated. 
All 1-ton chlorine containers are equipp 
ed with fusible metal type safety relief devices, called fusible plugs, which are designed to melt in the event of a fire or other high temperatures, to relieve pressure and prevent a catastrophic rupture of the container. 
Emergency showers and eye wash stations are provided at each building.  Fire extinguishers are available at both the pump station and filter building.      
Entry into Westlake FP is controlled by a fence and gate.  Visitors and contractors must be approved by Westlake FP staff prior to entry into the facility.  The chemical building remains locked and only a limited number of Westlake FP staff have keys. 
Offsite Consequence Analysis Results 
As required by 40 CFR and 19 CCR, Division 2, Chapter 4.5, the offsite consequence analysis includes consideration of two release scenarios, identified as "worst case" and "alternative" release scenarios.  The worst-case release scenario requires that a release involving the entire contents of the single largest vessel or pipe 
be evaluated for off-site impacts.   The alternative release scenario represents a more realistic, but still highly unlikely, release scenario. 
Only passive or administrative controls are allowed to be considered under the worst-case release scenario in analyzing offsite impacts.  The worst-case release scenario for Westlake FP is the rupture of a chlorine storage container with a maximum capacity of 1 ton, resulting in a release of 2,000 pounds of chlorine over a 10-minute duration.  The released liquid is assumed to quickly volatilize and to disperse as a vapor cloud.  In practice, this type of total release of a container would be unlikely to occur during the lifetime of the plant, and the conditions assumed as part of the scenario are not consistent with those that exist at the filtration plant. 
The distance to the toxic endpoint was estimated using the Dense Gas Air Dispersion (DEGADIS 3.0.3) model.  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.  The toxic endpoint selected by EPA and CalARP was 3 ppm.  In addition, all required EPA-model input parameters were included in completing this activity, including meteorological conditions that result in the greatest hazard - a very stable atmosphere (F stability class), wind speed of 1.5 meters per second (approximately 3.4 miles per hour), highest daily maximum temperature (110 degrees F), and average humidity (51 percent).  The results of the dispersion modeling analysis for this worst-case release scenario indicate that this scenario would have an offsite impact. 
The alternative release scenario is more likely to occur than the worst-case release scenario, but still is highly unlikely.  Unlike the worst-case release scenario, active controls can be considered in analyzing the alternative release scenario.  Active controls consist of mechanical, electr 
ical, or human input.  The alternative release scenario considered for Westlake FP consisted of a leak in the vacuum regulator and automatic activation of the emergency chlorine scrubber system to control the leak.  Because of the scrubber, no chlorine is released.  The alternative release scenario for Westlake FP does not have an offsite impact.  Because of a software error in RMP*Submit, a value of zero cannot be entered for the quantity released or for the release rate.  Therefore, 1.0 lbs and 0.1 lb/min have been entered into RMP*Submit as the quantity released and the release rate, respectively.   
Summary of the Accidental Release Prevention Program and Chemical-Specific Prevention Steps  
Westlake FP is in full compliance with all Federal and State Process Safety Management (PSM) requirements.  Chemical-specific prevention steps include availability of self-contained escape breathing apparatus, worn by the operators during connection and disconnection of the chlorine supplies; a 
wareness of the hazardous and toxic properties of chlorine; and the presence of chlorine detectors, a scrubber, and alarms. 
Westlake FP's accidental release prevention program is based on the following key elements: 
7 Detailed management system and clear levels of responsibilities and team member roles 
7 Comprehensive safety process information that is readily available to staff, emergency responders, and contractors 
7 A comprehensive preventive maintenance program performed by chlorine system specialists 
7 A process hazard analysis of equipment and procedures with participation and review by operation and maintenance staff  
7 Use of state-of-the-art process and safety equipment 
7 Use of accurate and effective operating procedures, written with operations and maintenance staff participation 
7 High level of training of operators and maintenance staff 
7 Implementation of an incident investigation, inspection, and auditing program using qualified staff 
Five-year Accident History Summary 
The CalARP regulations require that facilities compile a history of accidents involving a release of chlorine or sulfur dioxide that could have cause safety or health hazards (deaths, injuries, property or environmental damage, evacuations, or sheltering in place).  The facility must report any accident within the last 5 years.  At Westlake FP, there have been no accidents at least the course of this required reporting period. 
Emergency Response Program Summary 
Westlake FP has established a written emergency response program to be followed by employees, to help them safely respond to any accidental release of hazardous substances.  This program has been coordinated with the County of Los Angeles Fire Department, which is a member of the Local Emergency Response Planning Committee (LEPC).  This program includes an emergency response notification plan.  Emergency response drills and drill evaluations are conducted every 12 months; emergency operation and response procedures are also  
reviewed at that time.  In the event of an emergency, community-wide notification systems are in place and the County of Los Angeles Fire Department coordinates the response actions.  
Planned Changes to Improve Safety 
As new technology and new regulations develop, facilities using chemicals as part of their processes have opportunity to further improve safety.  Changes to improve safety (recommended actions) were identified for the chlorine process in 1990 under the State of California Risk Management and Prevention Program (RMPP).  In addition, the 1992 process hazard analyses (PHAs) for chlorine process was reviewed and revalidated in 1998.  The PHAs were further reviewed in January 1999 under the RMP and CalARP program requirements.  As a result, additional modifications are underway to improve the safety of the chlorination system, expected to be fully implemented by December 1999.  The implementation of these recommendations will further improve the safety of the covered process 
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