Stewart Creek Wastewater Treatment Plant - Executive Summary |
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The Stewart Creek Wastewater Treatment Plant facility uses both Chlorine and Sulfur Dioxide, which are considered hazardous by the EPA. The same properties that make Chlorine and Sulfur Dioxide valuable as water treatment Chemicals also make it necessary to observe certain safety precautions in handling both materials. The prevention of unnecessary human exposure reduces the threat to the health and safety of employees as well as to nearby members of the community. The primary goal of this Risk Management Plan is to ensure the safety of the employees of this facility and all residents that may be impacted by a release from this facility. It is the policy of The Colony to adhere to all applicable federal and state rules and regulations. Safety depends upon the manner is which Chlorine and Sulfur Dioxide are handled, the safety devices inherent in the design of the facility, and the training of the personnel. This Risk Management Program, including the Emergency Response Program, w as developed with the assistance of ALTEC Environmental Consultants, Inc. and NRS Consulting Engineers, Inc. The Emergency Response Plan includes procedures for notification of the appropriate agencies and potentially affected members of the community. In addition, it provides procedures for mitigating any releases that may cause harm to the community. The primary purpose of this facility is to treat the wastewater by utilizing chemicals such as Chlorine and Sulfur Dioxide. Chlorine and Sulfur Dioxide are received in individual one-ton cylinders or 150-pound cylinders and stored until needed. Chlorine and Sulfur Dioxide are injected into the wastewater treatment system by automatic feeders. The feed system uses a vacuum "shut-off" system which is designed to automatically shut the system down if a leak occurs. Access to the site is restricted to authorized facility employees, authorized management personnel and authorized contractors. The regulated substances handled at this f acility are Chlorine and Sulfur Dioxide. The maximum amount of Chlorine stored at the facility is 12,000 pounds. The maximum amount of Sulfur Dioxide stored at this facility is 1,800 pounds. The worst-case scenario is failure of and total release from the largest storage tank when filled to capacity, resulting in a release of 2,000 pounds of Chlorine. Both Chlorine and Sulfur Dioxide create a hazard when released. They are both toxic materials, with the same distances to their endpoint based on the EPA's document entitled "Back Up Information For the Hazard Assessment in the RMP Offsite Consequence Analysis Guidance." However, as Chlorine is the more toxic of the two chemicals, a worst-case scenario of Chlorine has been used. Active mitigation has been considered for this scenario. The Chlorine storage tanks are located in the Chlorine Cylinder Breezeway which is constructed of a concrete wall on one side and three open sides. It is assumed that the entire contents of the cyl inder are released as a vapor. The distance to the endpoint of 0.0087 mg/l for the worst-case scenario is 1.3 miles. The Sulfur Dioxide tanks are located within an enclosed building and has an endpoint of 0.3 miles. An alternative scenario was determined for this facility. However, the alternative release should be minimal due to the type of control systems in place. The vacuum "shut-off" system has been determined to be effective in preventing greater than small quantities of Chlorine or Sulfur Dioxide being released. Estimations based on the line capacity for feeder lines would be approximately 10 pounds released into the atmosphere under this scenario. This quantity of Chlorine or Sulfur Dioxide vapor release would result in a distance to endpoint of approximately 0.1 of a mile. This wastewater treatment facility complies with EPA's Accidental Release Prevention Rule and with all applicable State of Texas codes and regulations. There has been no accidental release of Chlori ne or Sulfur Dioxide in the last five years. The Emergency Response Program was developed for The Colony and the surrounding areas with the assistance of NRS Consulting Engineers, Inc. This program has been discussed with the Texas Office of Emergency Preparedness and The Colony Fire Department. The Chlorine feed system was placed in online in 1976. The Sulfur Dioxide feed system was placed on line in 1992. The Chlorine and Sulfur Dioxide feed systems meet all design requirements for and comply with all applicable regulations for wastewater treatment facilities. |