West Wastewater Treatment Plant - Executive Summary

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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 La Marque 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 La Marque 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 and cylinders are stored inside buildings, which act as passive mitigation in the event of a release.   The sulfur dioxide is below 
the threshold quantity, therefore it is not regulated under 40 C.F.R. 68, but some of the information is included for employee awareness. 
Chemical                                                         Maximum Inventory (lb)                Threshold Quantity (lb) 
Chlorine                                                                     8,900                                                2,500 
Sulfur Dioxide                                                            4,650                                                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 chlorine is 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                                                   1 
Surface Roughness                                                       1                                                   1 
                                                                                Chlorine                                        Chlorine 
End P 
oints                                                                 0.0087                                           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                                          Chlorine 
Impact Radius (miles)                                                     3                                                     0.4 
Estimated Population with Impact Area                      9,600           
Accidental Release Prevention Program 
The City of La Marque 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.
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