City of Meriden - BroadBrook Water Treatment Plant - Executive Summary
Executive Summary |
City of Meriden - Broad Brook Water Treatment Plant
1.Accidental Release Prevention and Emergency Response Policies
The City of Meriden (City) Broad Brook Water Treatment Plant provides drinking water to the City. Unfinished water undergoes a number of purification steps prior to distribution. Chlorine gas, stored in one-ton and 150-pound cylinders, is used as part of the purification process twelve months of the year. By virtue of the toxic effects associated with chlorine, it is necessary to observe certain safety precautions in handling the chemical to prevent unnecessary human exposure, to reduce the threat to employees of the City, and to reduce the threat to nearby members of the community. The City is strongly committed to employee, public and environmental safety. Safety at the facility depends upon the manner in which chlorine is handled as well as on the various safety devices incorporated into equipment design. Furthermore, comprehensi
ve training received by City employees adds to the inherent safety of chlorine storage and use at the facility.
2.The Stationary Source and the Regulated Substances Handled
Chlorine is the only chemical used or stored at the City that is subject to the 40 CFR Part 68 Chemical Accident Prevention Provisions because it is stored above the threshold amount. Chlorine cylinders are shipped by truck in both one-ton and 150-pound cylinders and are received at the facility's Administration Building. The cylinders are off-loaded by truck cranes onto a platform outside the chlorine storage room. Facility hoists are then used to move the cylinders into place inside the chlorine room. A maximum of two one-ton cylinders are hooked up at a time and two others are used as full spares. The maximum inventory of 150-pound cylinders at any one time is 27. An adjacent Injector Room houses the chlorine injectors. Chlorine detectors with alarms are located in both the Chlorine Storage and Injector
Rooms. Access to these rooms is restricted to authorized facility employees, authorized management personnel and authorized contractors.
The maximum amount of chlorine that can be stored at this plant is approximately 12,050 pounds, based on inventory records and the capacity of the storage areas.
3. The Worst Case Release Scenario(s) and the Alternative Release Scenario(s)
The worst-case scenario involves the release of a single one-ton cylinder outside of the building, while being offloaded from a truck or hoist. In accordance with EPA procedures, this scenario assumes that the cylinder fails and that the entire contents (2,000 pounds) is released to the atmosphere in 10 minutes. The estimated distance to toxic endpoint, determined using the procedures in EPA's Offsite Consequence Analysis Guidance, is 3 miles. According to Landview III (U.S. Department of Census 1990 database), approximately 32,600 people live within the worst-case impact radius of 3 miles. Public receptors
identified within the distance to toxic endpoint include residences, a school, and commercial, office or industrial areas. No environmental receptors were identified within the distance to endpoint.
The alternative case scenario assumes a failure of the 1-in. piping that carries the chlorine gas from the two one-ton cylinders on-line at a time. However, the release rate is limited by the release through the two 5/16" valves on each cylinder. The leak is assumed to occur inside the building. Therefore, the passive mitigation provided by the building is taken into account. The release rate, determined in accordance with EPA guidance, is estimated to be 29.7 pounds per minute for a duration of 137 minutes. The estimated distance to toxic endpoint, estimated in accordance with EPA OCA Guidance is 0.2 miles. According to Landview III's census database, there are 100 people living within the alternative case impact radius of 0.2 miles. Public receptors identified within the distance
to toxic endpoint include residences. No environmental receptors were identified within the distance to endpoint.
4.The General Accidental Release Prevention Program and the Chemical-Specific Prevention Steps
The City has taken all the necessary steps to comply with the accidental release prevention requirements set out under 40 CFR part 68 of the EPA. The City is also in compliance with the OSHA Process Safety Management Rule.
The following sections briefly describe the release prevention program that is in place at the City.
The City maintains a detailed record of written safety information, which describes the chemical hazards, operating parameters and equipment designs associated with all aspects of the chlorine storage and transfer processes.
Process Hazard Analysis
A checklist/what-if methodology is used to carry out process hazard analyses at the facility. The reviews focus on operating procedures, equipment functions and handling practices to identify
possible hazards. The studies are undertaken by a qualified personnel with extensive knowledge of facility operations and are revalidated at a regular interval of five years. Any findings related to the hazard reviews are addressed in a safe and timely manner.
For the purposes of safely conducting activities within the covered process, the City maintains written operating procedures. These procedures address various modes of operation such as initial startup, normal operations, temporary operations, emergency shutdown, emergency operations, normal shutdown and startup after a turnaround. The information is regularly reviewed and is readily accessible to operators involved with the processes.
The City has a comprehensive training program in place to ensure that employees that are operating processes are completely competent in the operating procedures associated with this process. New employees receive basic training in process operations followed b
y on-the-job supervision until they are deemed competent to work independently. Refresher training is provided at least every three years and more frequently as needed.
The City carries out maintenance checks on process equipment to ensure proper functioning. Maintenance activities are carried out by qualified personnel with previous training in these practices. Furthermore, personnel are offered specialized training as needed. Any equipment deficiencies identified by the maintenance checks are corrected in a safe and timely manner.
The City conducts audits on a regular basis to determine whether the provisions set out under the RMP rule are being implemented. These audits are carried out at least every 3 years and any corrective actions required as a result of the audits are undertaken in a safe and prompt manner.
Historically, there have been no incidents resulting in offsite impacts due to chlorine releases. However,
in the event of a release, the City has a program in place to promptly investigates any incident that has resulted in, or could reasonably result in, a catastrophic release of chlorine. These investigations are undertaken to identify the situation leading to the incident as well as any corrective actions to prevent the release from recurring. All reports will be retained for a minimum of 5 years.
5.Five-year Accident History
The City has had an excellent record of preventing accidental releases since it began operations. Due to the City's stringent release prevention policies, there have been no accidental releases involving chlorine.
6.Emergency Response Plan
The City's response to an accidental release involving chlorine is to immediately contact the City of Cheshire Fire Department. Other than responding to a minor chlorine leak that can be addressed by on-site personnel, all major leaks will only be handled by outside emergency responders.
The Local Emergency Planning Commit
tee (LEPC) is located at the Town of Cheshire Fire Department. The City's emergency response procedure has been coordinated and verified with the Chairperson of the LEPC, who is the Cheshire Fire Chief.
7.Planned Changes to Improve Safety
Any recommendations coming from development of the Risk Management Plan have been implemented as of the date indicated below.