Leesburg Water Treatment Plant - Executive Summary
The City of Leesburg owns and operates the Leesburg Water Treatment Plant (WTP), located at 223 South Fifth Street in Leesburg, Florida. Like the majority of municipal water treatment plants in the United States, gaseous chlorine is used at the Leesburg WTP as a disinfectant to destroy pathogenic organisms in the treated water prior to its distribution to customers. The popularity of chlorine as a water disinfectant is mainly due to its effectiveness and ability to provide a measurable residual. |
The same properties that make chlorine valuable as a disinfectant also make it necessary to observe certain safety precautions in handling chlorine as a safeguard to our workers, our community, and the environment. Chlorine is notably irritating to the eyes, nose, throat and lungs. More serious human health effects could result from much higher chlorine exposure, such as intense coughing, chest pains, and in extreme cases, death.
The City's commitment at the Leesburg WTP is to store, hand
le and use chlorine in a manner that achieves the needed benefits of disinfection while minimizing both onsite and offsite risks. This is accomplished by designing a safe process, maintaining the process in optimum working condition, operating safely through documented procedures and extensive training, and arranging for an emergency response capability to minimize the consequences of a chlorine release, should a process accident ever occur.
Accidental Release Prevention and Emergency Response Policies
It is the City's policy to adhere to all applicable Federal, State of Florida and local rules and regulations. This specifically includes compliance with the Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA) rules for chlorine accidental release prevention and emergency response.
The primary measures for accidental chlorine release prevention are contained in the document entitled Process Safety Management/ Risk Management Program for th
e Leesburg Water Treatment Plant. This process safety management (PSM) document was prepared in conformance with the EPA risk management rules, as well as industry-specific guidelines and best management practices relevant to release prevention. Leesburg's Water Treatment Superintendent has the responsibility for ensuring that this program is implemented in the workplace as written.
The Leesburg WTP emergency response plan relies on a team of offsite mutual-aid groups such as fire and rescue services. The emergency response plans at Leesburg WTP are based on the Incident Command system, where onsite responders work in coordination with local hazardous materials response teams to implement the City and regional response plans. Leesburg WTP's personnel receive hazard awareness training to understand how to recognize emergencies and to initiate the Incident Command system.
Stationary Source and Regulated Substances Handled
Chlorine is received by the facility by truck and is stored
in one-ton chlorine cylinders fabricated to Department of Transportation (DOT) specifications. Upon arrival at the site, all chlorine cylinders are inspected and if there is any doubt about the integrity of the cylinder, it is promptly refused. Once accepted, the cylinders are chained in place and stored inside a storage area for protection against radiant heat. Two cylinders are connected to the disinfection process: one is in-use, and one is as standby. The standby cylinders will be switched over when the in-use cylinders become empty, ensuring continuous disinfection. The maximum intended chlorine inventory at Leesburg WTP is 9500 pounds of chlorine stored in the building, including the 150-pound cylinders used at the satellite treatment plants.
The Worst-Case and Alternative Chlorine Release Scenarios
As part of Leesburg WTP's emergency prevention and response efforts, a hazard assessment was conducted in compliance with EPA requirements contained in 40 CFR 68, Subpart B. T
he hazard assessment included the development of worst-case and alternative release scenarios.
EPA defines a worst-case release as a scenario involving the greatest amount held in a single vessel or pipe. In Leesburg WTP's case, this involves the release of the entire contents of a one-ton chlorine cylinder. The release is assumed to occur over a 10-minute period. Applying the worst-case parameters to the worst-case situation results in a distance to chlorine endpoint (defined as 0.0087 milligrams per liter) of 1.3 mile.
EPA defines an alternative release as a scenario more likely than the worst-case, but that nevertheless results in an impact offsite (unless no such release is possible). Passive and active mitigation measures (chlorine detection, operator response, etc.) are considered in this scenario. The scenario involved the release of chlorine gas through a failure of a lead washer on the gas cylinder connection. Response time (leak detection to leak closure) is conservat
ively assumed to occur in 45 minutes. This scenario results in a distance to chlorine endpoint of less than 0.1 mile.
The distance to endpoint calculations were performed using EPA's RMP*Comp model. The RMP*Comp model was developed specifically for compliance with the accidental release prevention requirement for predicting the travel distance of an accidental release.
General Accidental Release Prevention Program and Specific Prevention Steps
The City's PSM document contains 13 essential release prevention elements. Some of the key accidental release prevention elements of the PSM program are as follows:
* Process hazard analysis: This analysis was performed for each step in the chlorine process, to identify potential process failure scenarios and the appropriate prevention or response measures. The process hazard analysis will be updated every 5 years.
* Operating procedures review: The review was conducted to ensure that operators are given clear, written instruc
tions for safely operating the chlorine process.
*Training programs: Training is given to each employee assigned to the process with continuing operator training thereafter, with an emphasis on safe chlorine handling and emergency response.
* Mechanical integrity: The integrity and reliability of the process is maintained by implementing preventive maintenance and routine inspection and testing procedures.
* Incident Investigation: The City investigates within 48 hours any accidents or "near misses" that could have resulted in a chlorine release, in order to develop measures to prevent a recurrence.
The above elements are only part of Leesburg WTP's aggressive safety program. In addition to the Program 3 prevention program elements, the City has developed related OSHA safety programs such as hot work and confined space. These OSHA safety programs apply to both City and contractor employees.
Five-year Accident History
There have been no accidents involving chlorine at the Lees
burg WTP in the past five years.
Emergency Response Program
The emergency response plan covers all aspects of emergency response including escape procedures and routes, procedures for post-evacuation employee accounting, notification procedures, rescue and medical duties, and response procedures for spills or leaks. If a major chlorine leak were to occur, the emergency plan requires immediate notification of the regional hazardous materials response teams for assistance, including orderly evacuation or sheltering-in-place of the surrounding community.