Salina Water Treatment Plant - Executive Summary
Executive Summary |
The City of Salina owns and operates the municipal water treatment plant, located at 401 South Fifth Street, Salina, Kansas. This plant uses chlorine for disinfection. Chlorine is a hazardous substance that, if released, poses a significant threat to the health of plant personnel and Salina citizens.
The Salina Utilities Department developed a Risk Management Plan (RMP) for control of catastrophic releases of hazardous substances, such as chlorine, from the water treatment plant. Development, implementation, registration, and submittal of the RMP, fulfills requirements of the U.S. Environmental Protection Agency's (EPA) Risk Management Plan regulations (Federal Register (FR) 61 , p. 31668). This program continues EPA's commitment to the protection of the public and environment. The intent of the regulation is to lessen the number and severity of chemical accidents.
The water treatment plant has the capacity to store 36,000 pounds of chlorine. Since th
is quantity exceeds the EPA's RMP regulation thresholds, chlorine must be addressed in the RMP. The water treatment plant does not contain any other toxics or flammables above threshold quantities that are regulated by 40 Code of Federal Regulations (CFR) Part 68.
Accidental Release Prevention and Emergency Response Policies
The City of Salina, Kansas (Salina) Water Treatment Plant (WTP) prevents accidental releases of chlorine by training and adhering to codes and good engineering practices. In the WTP's prevention program, safety information, hazard reviews, operating procedures, training, maintenance, compliance audits, and incident investigations are continuously updated. Every employee of the Salina WTP remains aware of the potential for chlorine releases and disturbance of the systems.
In an emergency, the WTP's first consideration is the safety of personnel and the community. The second consideration is the protection of property, equipment, and the facility. The Salin
a WTP maintains emergency response procedures that allow WTP personnel to respond to releases when possible. The WTP relies on the Police Department, Fire Department, and the Saline County Emergency Management to assist in responding to emergency situations.
Offsite Consequence Analysis
An offsite consequence analysis evaluates a worst-case and alternative release scenario to determine distances from the WTP at which chlorine would affect population and environment receptors should a release occur. A worst-case release scenario involves a total release of the largest vessel containing chlorine, and this case represents the worst possible scenario regardless of the low probability of such an event. The alternative case represents a more probable scenario, and this scenario is more suitable in emergency planning. The Salina WTP implements safe working practices to prevent chlorine releases.
Worst-Case Release Scenario
Since the Compliance Guidance and Model Risk Management Prog
ram for Water Treatment Plants (guidance) published by the American Water Works Association Research Foundation (AWWARF) specifically focuses on water treatment plants, this guidance was used to determine distances to endpoints for chlorine. The guidance's Area Locations of Hazardous Atmospheres (ALOHA) model, developed by the National Safety Council (NSC) and Environmental Protection Agency (EPA), was selected to predict movement of chemicals in the atmosphere. ALOHA is an appropriate choice for modeling requirements because it is well documented, publicly available, and recognized by the water treatment industry as an applicable modeling tool. The scenario description for the storage vessels is a catastrophic failure due to corrosion, impact, or construction defects.
The worst-case release scenario involves the release of the largest amount from a single vessel for a gas stored as a liquid under pressure (chlorine), released in a ten-minute time period. The analysis considered
a wind speed of 1.5 meters per second and F atmospheric stability (the most stable atmospheric class). The ALOHA model used a release at ground level (0 feet) and urban topography surface roughness. To account for gas density in the dispersion analysis, chlorine was considered a dense gas. The temperature of the released liquid was taken as the highest daily maximum temperature of the previous three years, 105.80F. The highest temperature is used to simulate the worst-case environmental conditions.
A catastrophic scenario of a one-ton chlorine container is a 2,000-pound release at a rate of 200 pounds per minute. Including the temperature correction, the distance to the endpoint was 2.6 miles for a one-ton container.
The estimated affected population within the 2.6-mile radius is 36,000. The worst-case release scenario area of concern includes residential populations, institutions, including schools and hospitals, parks and recreational areas, and major commercial, office, and
industrial buildings. No national or state parks, forests, or monuments; officially designated wildlife sanctuaries, preserves, or refuges; or federal wilderness areas are within this area.
Alternative Release Scenario
Since alternative release scenarios are more likely to occur than the worst-case scenarios, these scenarios are more suitable in emergency planning. In selecting an alternative release scenario, the five-year accident history and hazard review were considered. The alternative release scenario assumed the standard modeling parameters: a wind speed of 3.0 meters per second, Stability Class D, relative humidity of 50%, and a temperature of 770F.
Based on a one-ton chlorine container feeding chlorine as a gas, the alternative scenario involved a tubing failure, a bad connection, or a valve failure resulting in the gas release through the 5/16-inch-diameter valve body opening. This scenario is a release from a horizontal tank with the release from a short pipe or val
ve in the top of the tank. This scenario assumed a 317-pound release, maximum average sustained release rate of 10.5 pounds per minute, and a 60-minute duration. As a very conservative estimate, the scenario does not consider the scrubber, resulting in an endpoint off-site (regulations state an off-site endpoint). The distance to end point in an urban setting is 0.48 miles. Barring an unforseen problem, the scrubber will mitigate the release and prevent the chlorine from leaving the building. The scrubber would remove the chlorine, using its "once through" three stage absorption system. In this case, the endpoint is not offsite, and the distance to end point is 0 miles.
The estimated affected population within the 0.48-mile radius is 3,200. The alternative release scenario area of concern includes residential populations, institutions including schools and hospitals, parks and recreational areas, and major commercial and office buildings. No national or state parks, forests, o
r monuments; officially designated wildlife sanctuaries, preserves, or refuges; or federal wilderness areas are within this area.
Accidental Release Prevention Program
Salina prepared an accidental release prevention program. Salina WTP's prevention program consists of safety information, process hazard analysis, operating procedures, training, maintenance, management of change, prestartup review, compliance audits, incident investigations, employee participation plans, hot work permits, and contractor safety programs.
To better understand chlorine and the WTP chlorine system, the Salina WTP compiled chlorine safety information, including: Material Safety Data Sheets (MSDS); maximum intended inventory; safe upper and lower temperatures, pressures, and flows; equipment specifications; and codes and standards used to design, build, and operate the chlorine systems.
The Salina WTP analyzed potential hazards associated with the chlorine system to identify, evaluate, and control
any risks associated with chlorine. This process is called a hazard analysis (PHA). The PHA team consisted of plant management, process operation and maintenance personnel, and consulting process design engineers. The team analyzed the hazards associated with the chlorine process using a "what-if" technique. The PHA team made recommendations and set a schedule for implementation. In addition to operating procedure changes, the PHA team recommended that a portion of Fourth Street should be closed to the public, restricting access to chemical delivery, plant maintenance, and trains.
The Salina WTP has adopted written standard operating procedures (SOPs) that provide system descriptions, specifications, and operating procedures for the chlorine system. The procedures address initial startup, normal operations, normal and emergency shutdown, inspections, temporary operation, restartup, and consequences of deviation.
The Salina WTP implemented a Risk Management and Chlorine
Safety Training Program with guidelines for conducting regular, structured plant training for personnel, including operators and maintenance mechanics. Records of the training program, including content of the course, course manual, examination, and record of attendance are maintained.
The management of change program is intended to avoid making any change in the chlorine process, equipment, technology, or procedures that would increase the potential for a hazardous release. Management of change forms are used whenever the plant considers a change in the equipment or controls of the chlorine system.
The prestartup review allows Salina to verify that it has taken appropriate hazard control steps before any new process starts up. The prestartup review program involves a safety review procedure, schedule, and record keeping checklists.
Preventative maintenance, inspection, and equipment testing is performed to ensure safe operations at the Salina WTP. The maintenance p
rogram includes a preventive maintenance schedule based on manufacturer's recommended instructions. The Salina WTP and maintenance contractors continually assess the compliance status of the chlorine facility through inspections and preventative maintenance.
The compliance audit process will be performed at least once every three years to ensure that the RMP procedures and practices are adequate and being followed. To complete a compliance audit, the Salina WTP must demonstrate that documentation, employees' knowledge (interviews), and physical facility (through inspection) comply with 40 CFR Part 68.
The RMP incident investigation program outlines the RMP investigation process. If the chlorine incident is reportable, the employee completes an Incident Report form and submits it to the Water Superintendent. An incident investigation team investigates how the incident occurred and determines whether errors can be corrected by instituting general or specific safeguards for th
e process or whether it is necessary to institute additional training for the employees.
The employee participation program allows Salina to use the information provided by operations and maintenance employees in the analysis of chlorine hazards and the development of precautions to prevent chlorine releases. Input from employees with direct working experience with the subject equipment and systems greatly increases the effectiveness of the RMP. Salina WTP and contract employees operating or maintaining the chlorine process have access to current MSDS, operating procedures, operating training manuals, and the emergency response plan.
The Salina WTP's safe work practices include control of access measures; preventive maintenance, inspection, and equipment testing; breaching containment and lockout/tagout procedures; and hot work permits. Salina uses a hot work permit program for all work around any flammable vapor areas. The program appears in this RMP document in order
to prevent damage to equipment that contains chlorine gas.
Salina requires any contractor who works with or near extremely hazardous substances to demonstrate its ability to work safely. This Contractor Safety Program applies to all contractors providing maintenance, repair, turnaround, major renovation, or specialty work on or adjacent to the Chlorination Facility. Using this procedure, Salina will identify contractors that can perform site activities without compromising the safety or health of Salina personnel or the public.
The Five-Year Accident History
The Salina WTP has not experienced any accidental releases from the chlorine processes that resulted in death, injury, or significant property damage on site or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage.
Emergency Response Plan
The Salina WTP developed an emergency response plan to provide direction to recognize a release, shutdown normal plant operations,
and initiate emergency plant operations. In an emergency, 911 will be called to notify the Police Department, Fire Department, and the Saline County Emergency Management. Every employee of the Salina WTP remains aware of the potential for chlorine releases and disturbance of the systems. Training on the emergency response plan and evacuation drills are conducted annually.
In an actual or potential emergency, the area of the emergency will be secured, appropriate persons will be notified, and the source will be stopped, if possible. Evacuation procedures include sounding an alert via radio; gathering at assembly areas where roll call will be taken; shutting down designated equipment; and posting security personnel to isolate the area.
Planned Changes to Improve Safety
To improve safety, the Salina WTP planned changes based on the Process Hazard Analysis (PHA) conducted for the chlorine system. The PHA prompted a list of recommendations that were implemented. The most sign
ificant changes to improve safety were changes to the standard operating procedures. Additionally, the PHA team recommended that a portion of Fourth Street should be closed to the public, restricting the area to chemical delivery, plant maintenance, and trains. Eliminating unauthorized traffic would reduce the chance of chemical delivery truck accidents and increase security around the chlorine facility.