Wastewater Treatment Plant - Executive Summary
EXECUTIVE SUMMARY |
We have adopted this Program in order to implement 40 C.F.R. 68, the federal requirements regulating Risk Management of Highly Hazardous Chemicals.
This Program will help prevent the occurrence of, or minimize the consequences of, catastrophic releases by stating our policies and procedures for the management of process hazards in start-up, operation, inspection, maintenance and the other matters addressed in the federal standard.
Our Program calls for maximum employee participation and includes all elements of the employee participation provisions of the standard. We shall, as a minimum: (1) consult with employees and their representatives on the conduct and development of the process hazard review and other elements of the risk management plan, and (2) provide to our employees and their representatives access to the process hazard review and all other information required to be developed under that standard.
Accidental Release Prevention and Emergency Response
The City of Sherman believes that preventative maintenance is the key to minimizing the potential for accidental releases. Standard Operating Procedures (SOPs) have been reviewed and revised to enable the employees to perform their work in a safe and efficient manner.
The City of Sherman has taken steps to educate and inform the operators, supervisors, and maintenance crews in the appropriate response to an accidental release. The training includes classroom training and operating procedures on the proper response to emergency situations.
Stationary Source and Regulated Substances
The Wastewater Treatment Plant utilizes chlorine for disinfection and sulfur dioxide for dechlorination of the treated wastewater. The maximum inventory and threshold quantities for these chemicals are shown below. All chlorine and sulfur dioxide containers are stored and utilized in separate areas. The chlorine is stored outside or in an open-sided covered shed. The sulfur dioxide is sto
red in a building, which will act as passive mitigation in the event of a release.
Chemical Maximum Inventory (lb) Threshold Quantity (lb)
Chlorine 28,000 2,500
Sulfur Dioxide 8,000 5,000
Offsite Consequence Analysis
The offsite consequence analysis includes a worst-case release scenario and an alternative release scenario as defined in 40 C.F.R. 68. A dense-gas dispersion model (SLAB) was used to determine endpoint distances for both scenarios. A dense-gas model is required since both chlorine and sulfur dioxide are heavier than air. The model's input parameters are summarized in the table below.
SLAB Input Parameters
Windspeed (m/s 1.5 3
Atmospheric Stability Class F D
Temperature (0 F) 104 104
Humidity (%) 50 50
Height of Release (m) 0 1
Surface Roughness 1 1
Chlorine Sulfur Dioxide
End Points 0.0087
The results of the air dispersion model are summarized in the table below along with the estimated population within the impact area. The population data was estimated using the Block Uniform Density Group Method in Landview III, which uses the 1990 U. S. Census data to estimate population. The public and environmental receptors are listed in Section 8 of this plan.
SLAB Output Results
Worst-Case Scenario Alternative Scenario
Chlorine Sulfur Dioxide Chlorine Sulfur Dioxide
Impact Radius (miles) 4.5 3 0.6 0.4
Estimated Population with Impact Area 2,800 2,000 30 20
Accidental Release Prevention Program
The City of Sherman has implemented a
General Accidental Release Prevention Program to minimize releases. This Program includes: safety information on the covered chemicals, hazard reviews, operating and maintenance procedures, training, compliance audits, incident investigations, and emergency response procedures.
Five-year Accident History
In the last 5 years, there have not been any accidental releases from the covered process that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering-in-place, property damage, or environmental damage.
Planned Changes to Improve Safety
The City of Sherman has implemented a Risk Management Plan (RMP) that meets or exceeds the requirements of 40 CFR 68. It is Sherman's philosophy to continually improve the safe working conditions of its employees to minimize accidents and reduce the potential for either an on-site or off-site release. With this in mind, Sherman is planning on incorporating many of the RMP
elements into other areas of the process not covered under 40 CFR 68 to improve the overall safety of the plant.