South Houston Wastewater Plant - Executive Summary

| Accident History | Chemicals | Emergency Response | Registration | Source | 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 Policies 
The City 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 EPA has adopted a policy for non-responding facilities (another entity has agreed in advance to respond to the release).  This facility is a non-responding facility.  The Fire Department is the first responder. 
This emergency response program does not include responses to incidental releases of hazardous substances, including chlorine and sulfur dioxide, where the substances can be "adsorbed, neutralized, or otherwise controlled at the time of the release by employees in the immediate release area, or by maintenance personnel". 
The City has taken steps to train the operators, supervisors, and maintenance crews to be knowledgeable in the emergency  
response program.  The training includes classroom and hands on training on the proper use of emergency response equipment and procedures.  Above all, all employees know where the phone numbers of the first responders are located should a release occur. 
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. 
Chemical                                      Maximum Inventory (lb.)                                  Threshold Quantity (lb.) 
Chlorine                                        12,000                                                             2,500 
Sulfur Dioxide                               12,000                                                             5,000 
Offsite Consequence Analysis 
The offsite consequence analysis includes a worst-case release scenario and an alternative release scen 
ario 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 
                                                           Worst-Case Scenario                                    Alternative Scenario 
Windspeed (m/s)                                 1.5                                                                  3 
Atmospheric Stability Class                 F                                                                     D 
Temperature (0 F)                                 104                                                                 104 
Humidity (%)                                         50                                                                   50 
Height of Release (m)                           0                                                        
Surface Roughness                              1                                                                    1 
                                                             Chlorine                                                          Sulfur Dioxide 
End Points                                              0.0087                                                            0.0078 
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.  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)    
             4.2                      4.5                                                   0.6                   0.75 
Estimated Population                 150,000             180,000                                            3,900                6,200 
  with Impact Area 
General Accidental Release Prevention Program 
The City 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 processes 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 will address the recommendations of th 
e process hazards assessment for all areas of the prevention program and the emergency response program.  These updates will be completed by October 1999.
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