City of Ennis Wastewater Treatment Plant - Executive Summary |
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The City of Ennis, Texas is committed to provide a safe working environment for all employees through implementation of approved practices, design engineered equipment and materials. Also, the City of Ennis, Texas is committed to provide a continuous supply of safe water that is free of contaminants which cause diseases or to be toxic to consumers, or the environment. All city employees are committed to follow strenuous written safety procedures and are provided the needed equipment, tools, and training necessary to enforce safety procedures. The City of Ennis, Texas Water Treatment Plant is located at 4400 Beach Road, Ennis, Texas on a twenty acre site east of Lake Bardwell. The plant is designed to treat up to six (6) million gallons of water per day. The raw water source is pumped from Lake Bardwell and treated by rapid mixing flocculation, sedimentation, filtration, and disinfection. Liquid chlorine is used for pre-disinfection at the rapid mix, and liquid chlorine and anhydr ous ammonia are used for final disinfection after filtration. Maximum on site storage of liquid chlorine is 8,000 pounds and the maximum on site storage of anhydrous ammonia is 4,000 pounds. The City of Ennis, Texas Wastewater Treatment Plant is located at 401 Pland Road, Ennis, Texas on a fifteen acre site on the south side of our city. The effluent treatment capacity is two and one-half million gallos per day. The treatment process consist of clarification, aeration, sludge disposal, and final effluent disinfection. The final effluent is disinfected with liquid chlorine and sulfur dioxide dosage is applied for the purpose of dechlorination. The maximum on site storage of liquid chlorine is 6,000 pounds and the maximum on site storage of sulfur dioxide is 2,100 pounds. In order to avoid accidential release of regulated substances, operating personnel are required to study and follow written procedures as outlined in each designated hazardous work place. Chlorine feed systems a re designed with in-line back-up systems. Professional maintenance personnel services are used, if needed. All start-up and shut-down operating procedures are performed in accordance with written safety guidelines. An important practice includes having two (2) qualified operators to change-out or move chlorine cylinders, including the use of safety equipment and following written safety procedures specified in the safety program. There have been no accidential release episodes at either plant during the last five (5) years, a record for which we are proud, and a sign of the dedicated effort by our employees. In response to an accidential release of a regulated substance, operators are trained to identify and locate the source of the release, mitigate if possible, notify city emergency personnel, prepare emergency equipment and material for use, summon all utility department employees, determine the overall impact, follow the instructions of emergency personnel, take corrective act ions, follow through, and document all incurred actions by time and date. Emergency response to an accidential release will be made by the Ennis Fire Department. The Ennis Fire Department is a combination department (31 career/25 Volunteer), staffed 24 hours per day. The Ennis Fire Department has an ISO Class 4 Public Protection Classification. Fire department personnel are trained and have the capability to respond and mitigate hazards from an accidential release at either plant. The "Toxic Worst Case" senerios were chosen, based upon a chlorine release, and anhydrous ammonia release at the Water Treatment Plant, and a Chlorine release and a sulfur dioxide release at the Wastewater Treatment Plant. The safety record at both plants is excellent and the plant employees understand that their safety, and that of the public is their first action. The worst-case senerios are based upon a tank/cylinder leak at the bottom of the vessel. The tank/cylinder is at full capacity. Chlori ne leaks at 2,000 pounds over 10 minute duration. Anhydrous ammonia leaks at 4,000 pounds over 10 minutes. Sulfur dioxide leaks at 195 pounds over 10 minutes. The caculated data is as follows: wind 1.5 mps from SSE at 3 meters, Temp. 25 degrees C., Stability Class F, Unsheltered facility, rural, open country, no inversion height. Wind direction is based on DFW Airport wind-row data of 41% SSE for the area. Calculations were made using the RMP*Comp Ver. 1.06 program. The end point for chlorine is 1.3 miles, Anhydrous ammonia is .8 mile and Sulfur Dioxide is .2 mile. Current safety has been improved by a full compliment of self-contained breathing apparatus, wind direction indicator, radio communications, safety harness devices, and employee training. Both plants will have major up-grades beginning in 2001. These up-grades will increase capacity, improve safety and improve the quality of treatment. A liquid chlorine process alarm system will be added at each facility during t he up-grade. Other improvements will be made as needed. |