City of Maryville Wastewater Treatment Plant - Executive Summary |
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Executive Summary City of Maryville Wastewater Treatment Plant June 1999 1. Accidental Release Prevention and Emergency Response Policies The City of Maryville Wastewater Treatment Plant is strongly committed to employee, public and environmental safety. This commitment is inherent to an accidental release prevention program in place that covers areas such as design, installation, operating procedures, maintenance, and employee training associated with the processes at our facility. It is our policy to implement appropriate controls to prevent possible releases of regulated substances. Unforeseeably, if such a release does occur, we are completely coordinated with the City of Maryville Fire Department which provides highly trained emergency response personnel to control and mitigate the effects of the release. 2. The Stationary Source and the Regulated Substances Handled This facility is, as the name describes, a wastewater treatment facility serving Blount County and a few surro unding areas. There are two regulated substances present at the facility. These substances are chlorine and sulfur dioxide. Chlorine is used in the treatment of wastewater. Sulfur dioxide is used to de-chlorinate the water before releasing into the river. The maximum inventory of chlorine is 16,000 pounds. The maximum inventory of sulfur dioxide is 8,000 pounds. 3. The Worst Case Release Scenario and the Alternative Release Scenario To perform the required off site consequence analysis for the facility, we have used the software program, RMP*Comp, provided by the Environmental Protection Agency. The program provides the calculations needed for the analysis. The following paragraphs provide details of the chosen scenarios. Chlorine The worst case release scenario involves a catastrophic release of chlorine from the Wastewater Treatment Plant. The release scenario consisted of 16,000 pounds of gaseous chlorine being released simultaneously from 8 one ton cylinders in a ten mi nute time period. Under worst case weather conditions namely Class F atmospheric stability and 1.5 m/s windspeed, the estimated distance to the toxic endpoint is 6.3 miles. The toxic end point for chlorine is 0.0087 mg/L. This type of release would have significant off site impact. However, the worst case release is unlikely because 8 one ton cylinders is the maximum quantity that can be stored onsite. The inventory will be maintained at smaller quantities. The alternative release scenario involves a release of 2,000 pounds or 1 one ton cylinder of gaseous chlorine released in a ten minute time period. Under neutral weather conditions, Class D, and 3.0 m/s windspeed the estimated distance to the toxic endpoint is 0.2 miles. This type of release would not have an impact off site. The alternative release scenario was selected because the most likely event to occur would be a break in a connection or pigtail on the cylinder. This type of release would be limited to one cylinder. Procedures and preventative maintenance have been established to reduce the possibility of this event. Chlorine detection units are installed and allow for quick detection of chlorine leaks. Sulfur dioxide The worst case release scenario involves a catastrophic release of sulfur dioxide from the Wastewater Treatment Plant. The release scenario consisted of 8,000 pounds of gaseous sulfur dioxide being released simultaneously from 4 one ton cylinders in a ten minute time period. Under worst case weather conditions namely Class F atmospheric stability and 1.5 m/s windspeed, the estimated distance to the toxic endpoint of 0.0087 mg/L for sulfur dioxide is 4.6 miles. This type of release would have significant off site impact including public and environmental receptors. However, the worst case release is unlikely because 4 one ton cylinders is a maximum quantity that can be stored onsite. The inventory will be maintained at smaller quantities. The alternative release scenario invo lves a release of 2,000 pounds or 1 one ton cylinder of gaseous sulfur dioxide released in a ten minute time period. Under neutral weather conditions, Class D, and 3.0 m/s windspeed the estimated distance to the toxic endpoint is 0.2 miles. This type of release would have minimal off site impact. The alternative release scenario was selected because the most likely event to occur would be a break in a connection or pigtail on the cylinder. This type of release would be limited to one cylinder. Procedures and preventative maintenance have been established to reduce the possibility of this event. Sulfur dioxide detection units are installed and allow for quick detection of chlorine leaks. 4. The General Accidental Release Prevention Program and the Chemical Specific Prevention Steps The facility has taken all the necessary steps to comply with the accidental release prevention requirements set out under 40 CFR Part 68 of the Environmental Protection Agency. This facility is also sub ject to the requirements of OSHA Process Safety Management Standard under 29 CFR 1910.119. The following section briefly describes the elements of our release prevention program. Process Safety Information The City of Maryville Wastewater Treatment Plant maintains a detailed record of the written safety information that describes the chemical hazards, operating parameters and equipment designs associated with all processes. Process Hazard Analysis The facility conducts comprehensive studies to ensure that hazards associated with our processes are identified and controlled efficiently. The methodology used to carry out these analyses was the What If/Checklist. Any findings related to the hazard analysis are addressed in a timely manner. Operating Procedures For the purposes of safely conducting activities within the covered processes, the Wastewater Treatment Plant maintains written operating procedures. These procedures address various modes of operation such as initial startu p, normal shutdown, 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 in the processes. Training The facility has a training program in place to ensure that employees operating covered processes are completely competent in the operating procedures. New employees receive basic training in process operations followed by on-the-job supervision until they are deemed competent to work independently. Mechanical Integrity The wastewater plant carries out documented maintenance checks on process equipment to ensure proper functions. Process equipment examined by these checks include among others: piping systems, relief and vent systems and controls. Maintenance operations are carried out by qualified personnel with previous training in maintenance practices. Any equipment deficiencies identified by the maintenance checks are corrected in a safe and timely manner. Management of Change Written procedures are in place to manage changes in process chemicals, technology, equipment or procedures. Process operators, maintenance personnel or any other employee whose job tasks are affected by a modification in process conditions are promptly made aware of and offered training to deal with the modification. Pre-Startup Reviews Pre-startup reviews related to new processes and to modifications in established processes are conducted. These reviews confirm that construction, equipment, operating and maintenance procedures are suitable for safe startup prior to placing equipment into operations. Compliance Audits Compliance audits are conducted on a regular basis to determine whether the provisions set out under the RMP rule are being implemented. These audits will be carried out at least every three years and any corrective actions required as a result of the audits will be undertaken in a safe and prompt manner. Incident Investig ation The facility has a policy to promptly investigate any incident that has resulted in, or could reasonably result in a catastrophic release of chlorine or sulfur dioxide. These investigations are undertaken to identify the situation leading to the incident as well as any corrective actions to prevent the release from reoccurring. Employee Participation The management of the Wastewater Treatment Plant believes that process safety management and accident prevention is a team effort. Employees are strongly encouraged to express their views concerning safety issues and to recommend improvements. In addition, employees have access to all information created as part of the implementation to the RMP rule. Contractors On occasion, we hire contractors to conduct specialized maintenance and construction activities. Contractors are informed of the potential hazards related to the work and the processes. Contractors are also informed of procedures for emergency response in the event that an accidental release should occur. 5. Five-year Accident History The facility has had an excellent record of preventing accidental releases over the last five years . Due to stringent release prevention policies, there has been no accidental release during this period. 6. Emergency Response Plan A written emergency response plan is maintained at the facility. The plan includes all aspects of emergency response. We have coordinated with the City of Maryville Fire Department in the event of a release. 7. Planned Changes to Improve Safety State-of-the-art chlorine and sulfur dioxide systems were installed in May of 1999. The system should minimize accidental releases. |