South Houston Wastewater 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
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.