Front Royal Water Treatment Plant - Executive Summary |
|
1.0 SOURCE & SUBSTANCE The Town of Front Royal Water Treatment Plant is designed to supply the Town of Front Royal with up to three million gallons of drinking water each day. In order to remove harmful pathogens from water before it is distributed, the plant chlorinates water in the final steps of treatment. Three tons of chlorine are stored on site in the form of gas liquified by pressure. Chlorine is a water-soluble, poisonous gas that is highly irritating to the respiratory organs. At concentrations of 15 parts per million (ppm), chlorine is immediately irritating to humans by inhalation. At concentrations of 50 ppm, chlorine is dangerous even for brief exposures, and exposures of 1,000 ppm may be fatal even if exposure is brief. Long term damage from chlorine gas exposure includes changes in the trachea, bronchi, emphysema, and congestion in the respiratory system. Short term effects include coughing, vomiting, headache, and chest pains. However, the human olfactory s ense can detect chlorine concentrations as low as 3.5 ppm, so extensive exposure rarely occurs. 2.0 RELEASE SCENARIOS In accordance with federal regulation, plant management has modeled two accidental release scenarios: "worst-case" and "alternative-case." The Worst-Case Analysis uses conservative assumptions to determine the greatest distance that a release will travel before it is not longer a hazardous threat. The Alternative-Case Analysis demonstrates an off-site impact for a smaller release. Scenarios are described briefly below. A) Worst-Case Scenario for Chlorine Release The worst-case scenario describes a situation in which a one-ton storage container releases all 2,000 pounds of the chlorine gas it contains in ten minutes. Under stable atmospheric conditions with a one and one-half meter per second wind, toxic concentrations of chlorine gas would spread to a radius of 0.9 miles from the release site, affecting residences, a school and a national park. The resi dential population affected would be 447 people. Accordingly, safety inspections and safety plans have been completed in the fullest to prevent such an occurrence. B) Alternative-Case Scenario for Chlorine Release The alternate-case scenario describes a situation in which a one-ton storage container suffers a valve failure and releases 1,000 pounds of its chlorine gas in 67 minutes. Under slightly unstable atmospheric conditions with a three meter per second wind, toxic concentrations of chlorine would travel to a radius of 0.1 miles from the release site, affecting affecting a residential population of four people. Safety inspections and safety plans are in effect to ensure against this type of release. Several mechanisms already in place ensure quick response time and release control. These mechanisms include relief valves, manual and automatic shutoffs, alarms and emergency procedures, and emergency air supply. Also, the placement of chlorine containers within an enclo sed structure slows spread time, therefore increasing time for emergency response and public notification. Control mechanisms serve to make both release scenarios highly unlikely. 3.0 ACCIDENT HISTORY & ACCIDENTAL RELEASE PREVENTION PROGRAM The Town of Front Royal Water Treatment Plant can certify that there have been no releases of chlorine in the past five years that have resulted in any off site impact. The plant is proud of its accident-free history and has put into effect an extensive accidental release prevention program to maintain its excellent safety record. As an affected facility under Occupational Health and Safety Act Process Safety Management (OSHA PSM) requirements, the plant is a Program 3 participant. The most extensive of the three RMP programs, Program 3 includes a number of requirements that closely track OSHA PSM requirements. Program 3 also focuses on the off-site consequences of an accidental release. The prevention program outlines information and p rocedures regarding all aspects of safe operation, including process safety information, Process Hazard Analysis (PHA), operating procedures, mechanical integrity, and personnel training. The PHA is designed to be conducted by a cross-section of facility employees, with guidance from employees directly involved in the chlorination process. The PHA team identifies, evaluates, and implements controls associated with hazards in the chlorination process. The overall purpose of the PHA is to comply with the PSM/RMProgram regulations and to prevent or minimize the effects of a chemical release. The PHA team may conduct a new hazard analysis if significant modifications have been made to the current process or new regulated processes are added. PHAs are, however, updated and revalidated at least every five years after completion of initial PHAs. The program also ensures that the plant maintains up-to-date, accurate, written Operating Procedures that provide clear instructions for al l covered processes. Effective operating procedures, when combined with operator training, are instrumental in guaranteeing safe operation of the systems and preventing accidental releases. The mechanical integrity program is integral in preventing accidental chemical releases that may result from mechanical failure of improperly maintained equipment. This program outlines equipment maintenance, including maintenance procedures, testing, and inspection schedules and procedures, maintenance personnel training, correction of equipment deficiencies, and quality assurance of new equipment. Finally, personnel training practices ensure that all employees, including maintenance and contract employees, working on or near the chlorination process fully understand the processes and safety measures necessary for correct operation. All personnel currently working at the plant have been certified as having all of the required knowledge, skills, and abilities to conduct their jobs safely and efficiently. In addition, the plant will train and certify all new personnel as well as holding mandatory refresher courses for experienced personnel. The existing facility training includes the "Chlorine Safety for One Ton Containers" document and other associated training material. 4.0 EMERGENCY RESPONSE PROGRAM 40 CFR Part 68.90(b) states that "the owner or operator of stationary source whose employees will not respond to accidental releases of regulated substances need not comply with section 68.95 of this part provided that they meet the following: (1) For stationary sources with any regulated toxic substance held in a process above the threshold quantity, the stationary source is included in the community emergency response plan developed under 42 U.S.C. 11003;". Since the policy of the Front Royal Water Treatment Plant is to allow the emergency response teams organzied by the Town of Front Royal and the LEPC to respond to emergencies at the plant, the Front Royal Water Treatment Plant is not required to comply with 40 CFR Part 68.95, pertaining to the development and implementation of an emergency response program. |