Bethune Point Wastewater Treatment Plant - Executive Summary
EXECUTIVE SUMMARY |
City of Daytona Beach owns and operates the Bethune Point Wastewater Treatment Plant, located at 1Shady Place Daytona Beach, Florida.
Like the majority of municipal wastewater treatment plants in the United States, gaseous chlorine is used at the Bethune Pointe plant as a disinfectant to destroy pathogenic organisms in the treated wastewater. The popularity of chlorine as a wastewater disinfectant is mainly due to its effectiveness and relatively low cost compared to other disinfection technologies.
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 Beth
une Point plant is to store, handle 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 the Daytona Beach Fire Department to provide 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 Bethune Point's commitment 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 conta
ined in the document Process Safety Management Program for the Bethune Point. This process safety management (PSM) document was prepared in conformance with the OSHA and EPA risk management rules, as well as industry-specific guidelines and best management practices relevant to release prevention. Bethune Point's Plant Manager has the responsibility for ensuring that this program is implemented in the workplace as written.
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 thoroughly inspected and if there is any doubt about the integrity of the cylinder, it is promptly refused. Once accepted, the cylinders are stored under a shelter on a storage pad. Four cylinders are connected to the disinfection process: two are in-use, and two are as standby. The standby cylinders will
automatically switchover when the in-use cylinders become empty, ensuring continuous disinfection. The maximum intended chlorine inventory at Bethune Point is 5 cylinders, or 10,000 pounds of chlorine.
The Worst-Case and Alternative Chlorine Release Scenarios
As part of Bethune Point's emergency prevention and response efforts, a hazard assessment was conducted in compliance with EPA requirements contained in 40 CFR 68, Subpart B. The 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 Bethune Point'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. In other words, any human
or environmental receptors within 1.3 mile of the chlorine storage building are within the worst-case distance.
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. Without an accident history on which to base a more likely scenario, a scenario was selected based on information provided in the Chlorine Institute Pamphlet 74, Estimating the Area Affected by a Chlorine Release. The scenario involved the release of chlorine gas through a failure in 0.25 inch whip leading to the gas cylinder. Response time is conservatively assumed to occur in 45 minutes. This scenario results in a distance to chlorine endpoint of 0.1 mile. The Intracoastal Waterway would be affected by this release.
The distance to endpoint calculations were performed using EPA's RM
P*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
Bethune Point'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 instructions 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.
* Contractors: The City ensures through its contract provisions that contractors supplying or working with chlorine are held to a standard of safety performance that complies with Bethune Point's safety goals and objectives, and also meets relevant agency requirements. For example, Bethune Point personnel make unannounced visits to the supplier's site to ensure that rules and guidelines concerning chlorine and cylinder integrity are being followed.
* Mechanical integrity: The integrity and reliability of the process is maintained by implementing preventive maintenance and routine inspection and testing procedures.
* Management of Change: The management of change procedures provide a systematic approach to evaluate and control the safety and health aspects of any significant change to the process chemicals, technology, equipment and operating 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 Bethune Point's safety program. In addition to the 13 PSM elements, Bethune Point has established related OSHA safety programs such as hot work and confined space. These OSHA safety programs apply to both Bethune Point and contractor employees.
Five-year Accident History
There have been no accidents involving chlorine at the Bethune Point plant in the past five years.
Emergency Response Program
The emergency response plan covers all aspects of emergency response including escape procedures and notification procedures, and response procedures for spills or leaks. If a major chlorine leak were to occur, the emergency plan requires immediate notification of the Daytona Beach Fire Department response teams for assistance, including orderly evacuation or sheltering-in-place of the surrounding community.