WCSA Water Treatment Plant - Executive Summary
* Accidental release prevention and emergency response policies |
The Washington County Service Authority (WCSA) is committed to meeting and exceeding the water/wastewater needs of our customers, as well as complying with all regulations, including safety. In carrying out this mission, WCSA's Board of Commissioners has funded specific safety equipment and training line items in the budget, in addition to uniforms, tools, and personal protective equipment. Safety training is mandatory for all employees, including the water treatment plant (WTP).
WCSA has instituted a safety committee, and monthly safety training. Our staff, including the General Manager and senior staff, provides much of our training. We are participating in voluntary safety review established by the Virginia Department of Labor and Industry (SHARP program).
The WTP operators work to prevent accidental releases of chlorine by developing and following operating procedures. The process equipment is inspected daily.
WCSA's policy is for emergency response to an accidental release of chlorine to be coordinated through Washington County Department of Emergency Services.
* WCSA's facility and the regulated substances handled
WCSA WTP produces pure, safe drinking water for many residences, schools, businesses and industries and Washington County, Virginia. The WTP is a conventional coagulation/filtration/disinfection plant, drawing raw water from the Middle Fork of the Holston River for purification. The maximum capacity is 4.6 million gallons per day (4.6 MGD).
The last, and most important step in the water treatment process is disinfection, which destroys pathogenic microorganisms, organisms in water that cause diseases. Chlorine is the chemical added to the water to disinfect it.
Prior to use in our treatment process, the chlorine is stored at the WTP in cylinders holding 2,000 pounds of gaseous chlorine. A maximum of four cylinders (8,000 pounds) may be at the WTP at any time, including
the cylinder on-line (in use).
Chlorine was first used to disinfect water in 1908; thus, it is a long-established public health improvement still in use. Construction of WCSA's WTP was completed in 1976, and the facility has been in service ever since.
* Worst-case scenario and alternative release scenario
The WTP is a program 3 process. Two scenarios were evaluated with respect to off-site consequences of an accidental release of chlorine: a worst case release, and an alternative release.
For the worst-case, the scenario is a catastrophic failure of a 1-ton cylinder of chlorine. The failure would release the entire contents of the cylinder (2,000 pounds) over a ten-minute duration. Because the area is rural and the high temperature is between 88 F and 107 F, the effective distance from the WTP over which the chlorine could cause serious health effects (that is, 3 parts per million) is 3.04 miles. This distance was obtained from tables generated using the ALOHA model.
ircle of concern with radius 3.04 miles was draw with the WTP at its center. 2400 residents reside in this circle. This information was obtained from the U.S. Census Bureau. There are no schools, institutions, or sensitive environmental receptors contained within the circle. There are six "public receptors" (that is, locations with higher population concentration) contained within this area of concern:
General Engineering (127 employees), Hapco (108 employees), Mid-Mountain Foods (498 employees), Joy Technologies (250 employees), Mink Company (15-100 employees- seasonal), and the Southwest Virginia 4-H Center (summer resident camp).
The model does not account for changes in topography. In actuality, there is a 200 foot increase in elevation between the WTP and the public receptors listed above. Because chlorine is heavier than air, the likely route of any accidental release would be to follow the Middle Fork, and approximately 35 houses would be impacted within the area of conce
For the alternative release, the scenario is failure of a transfer hose or valve. Chlorine would release through the 5/16-inch valve opening. The failure would release 317 pounds over a 60-minute duration. Because the area is rural and the high temperature is between 88 F and 107 F, the effective distance from the WTP over which the chlorine could cause serious health effects (that is 3 parts per million) is 0.56 miles. This distance was obtained from tables generated using the ALOHA model.
The population within this alternative area of concern (centered at WTP) is 86. There are no "public receptors," and about 75% of this population resides at an elevation 120 ft higher than the WTP, with the same implications as mentioned above.
The area of concern for both scenarios is plotted, with diagrams available at the WTP and WCSA's main office.
* General accidental release prevention program and chlorine specific prevention steps
The WTP complies with OSHA's Process Safety Ma
nagement requirements, in addition to EPA's Risk Management Program. All employees at the WTP have state-issued waterworks operator licenses, which are granted only after passing a written test and meeting required work experience. Most employees have the highest rated license (Virginia Class 1). This indicates that our employees are well qualified and highly motivated.
The operators conduct daily inspections on the chlorine process, with scheduled preventative maintenance. Standard operating procedures have been developed and are followed, in order to minimize accidental releases. Monthly safety training is conducted for all WCSA employees, with additional training for WTP operators. Our commercial vendors and suppliers of chlorine have excellent safety training and knowledge, and can answer questions from the WTP staff.
* Five-year accident history
Guidelines for this Risk Management Plan include reporting any accidental releases of chlorine in the past five years. Not onl
y has there been no accidental releases in the past five years, our records indicate that since the WTP was constructed in 1976, there has not been an incident that injured or endangered our employees, the public, or the environment.
* Emergency response program
The WTP has completed plans for action in the occurance of an accidental release of chlorine. WTP employees have been trained to safely evacuate the facility. Response to the release will be coordinated throught the office of the Coordinator of Washington County's Emergency Services Department. The WTP is covered in the Emergency Services' emergency response plan. The Town of Abingdon Fire Department will provide response, with Washington County Sheriff's Department directing/rerouting traffic.
* Planned changes to improve safety
Several items are planned to improve the response to an accidental release of chlorine. A planning and coordination meeting of responders has been scheduled. This will allow the responders to
inspect the WTP, and foster communications. Practice "drills" will be held at least annually, and may include both "tabletop" review and an actual simulation of response to a release.