City of Jackson - Executive Summary
RMP Executive Summary |
1. Accidental Release Prevention and Emergency Response Policy
The City of Jackson Wastewater Treatment Plant (WWTP) accidental release prevention policy involves a unified approach that integrates technologies, procedures, and management practices. All applicable procedures of the U.S. Environmental Protection Agency (EPA) Prevention Program are adhearde to. The WWTP emergency response policy involves the preparation of response plans which are tailored to it's facility and to the emergency response services available in the community, and is in compliance with the EPA Emergency Response Program Requirements.
2. Stationary Source and Regulated Substances Handled
The City of Jackson WWTP Chlorination/Dechlorination Station has been installed to disinfect treated wastewater. The station includes treatment plant offices, a chlorination/dechlorination room, a chemical storage area, instrument rooms, and additional miscellaneous treatment basins. Chlorine a
nd Sulfur Dioxide are the regulated substances. The amount of chlorine connected to the manifold system are two one-ton cylinders with one empty or reserve cylinder. The amount of sulfur dioxide connected to the manifold system is one 1 ton cylinder. There are a maximum of 3 one-ton cylinders of chlorine and 2 one-ton cylinders of sulfur dioxide in the area.
3. Worst Case Release Scenarios and the Alternate Release Scenarios
The offsite consequence analysis includes consideration of two chemical release scenarios, identified as "worst cas release" and alternative scenario". Scenarios were conducted for both chlorine and sulfur dioxide releases. The first scenario is defined by EPA, which states that "the owner or operator shall assume the the ... maximum quantity in the largest vessel ... is released as a gas over 10 munutes," due to an inspecified failure. The alternative scenario is defined as "more likely to occur than the worst-case release scenario".
ion modeling has to be performed to determine the distance traveled by the chlorine and sulfur dioxide released before its concentration decreases to the "toxic enpoint" selected by EPA of 3 ppm, which is the Emergency Response Planning Guideline Level 2 (ERPG -2). This is defined by the American Industrial Hygiene Asociation (AIHA) as the "maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious helth effects or symptoms which could impair an individual's ability to take protective action." The residential population with a circle with a raduis corresponding to the toxic endpoint distance has to be defined, "to estimate the population potentially affected".
The worst-case release scenario at the Jackson WWTP involves 1) failure of the one ton cylinder of chlorine; and 2) failure of a one-ton cylinder of sulfur dioxide. The offsite consequence analysis f
or these scenarios were performed for the following conditions. The conditions are pre-defined by EPA, namely release of the entire amount as a gas in 10 minutes, use of the one-hour average ERPG-2 as the toxic endpoint, and consideration of the population residing within a full circle with radius corresponding to the toxic endpoint distance. EPA set these conditions to facilitate the performance of the offsite consequence analysis.
For the worst-case scenario, EPA-mandated meteorological conditions, namely Stability F, wind speed of 1.5 m/sec, temperature (25 degrees C), and average humidity (65%) were used. When atmospheric dispersion modeling for the worst case scenario was performed using the EPA assumptions, chlorine had a distance to toxic endpoint of 1.3 miles and an estimate of residential population potentially affected of 1,000 was obtained. Sulfur dioxide a distance to toxic endpoint of 1.3 miles and an estimate of residential population potentially affected of 1,000 wa
The alternative release scenario involved the rupture of the flexible connections (pigtails) connected to the one-ton containers. The amount of chlorine released is 900 lbs., at an average rate over one hour (the duration of the release) of 15.0 lb/min. The typical meteorological conditions used were Stability D, wind speed 3.0 m/s, average air temperature of 62 degrees F, and 63% average humidity. The estimated distances traveled to the toxic endpoint is .1 mile. For sulfur dioxide, a toxic endpoint of .1 mile was obtained and the estimate of residential population potentially affected of 100 was obtained.
Actuation of the chlorine leak detection system is an active mitigation measure used at this facility. During hours when the facility is not staffed, a alarm signal is sent to operators. This will alert the staff who can activate the emergency response plan.
4. General Accidental Release Prevention Program
The Jackson WWTP accidental release prevention program
is in compliance with the OSHA PSM rule and this rule. It is based on the following key elements:
* High level of training of the operators
* Preventive maintenance program
* Use of state-of the-art process and safety equipment
* Use of accurate and effective operating procedures, written with the participation of the operators
* Performance of a hazard review of equipment and procedures
* Implementation of an auditing and inspection program.
Chemical-specific prevention steps include availability of self-contained breathing apparatus (SCBA), awareness of the hazardous and toxic properties of chlorine, and presence of chemical release detectors.
5. Five Year Accident History
No accidental releases of chlorine or sulfur dioxide have occurred at this facility in the past five years.
6. Emergency Response Program
The facility has an emergency response program, which has been coordinated with local emergency response agencies. Joint training drills are planned to be conduct
ed with the local fire department on an annual basis. Emergency operation and response procedures are also reviewed at that time.
7. Planned Changes to Improve Safety
There are no plans to improve safety of the facility at this time.