Somerset Borough Wastewater Treatment Plant - Executive Summary |
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The Somerset Borough Wastewater Treatment Plant is permitted for a 2.0 MGD discharge. Actual flows are about 1.5 MGD for an annual average. The Plant utilizes grit and screenings removal, primary clarifiers, trickling filters for biological treatment, bio towers for biological ammonia nitrogen reduction, secondary clarifiers, and chlorine contact chambers for effluent disinfection. Wastewater is collected from Somerset Borough and portions of Somerset Township and conveyed to the treatment plant through the collection system and (5) pumping stations. Sludges that are removed from the treatment processes are thickened in a gravity thickener then stabilized in anaerobic digesters prior to belt press dewatering and landfill disposal. Chlorine is the chemical used for disinfection of the final effluent before discharging to the receiving waters. Chlorine is stored on site for this purpose. One ton containers are used. Typically, there is between 1800 and 3800 pounds on site at any given t ime. Chlorine is stored in the chlorine feed room and is fed to the system through a vaccum feed system. The amount of chlorine handled is two one-ton containers. A chlorine leak detector is provided in the chlorine feed room that will sound an alarm horn and activate flashing beacon lights. The detector is also hooked to an alarm panel and automatic phone dialer that will notify plant operators and emergency personnel in the event of a chlorine leak when the plant is unmanned. The amount of chlorine that is stored on site has been reduced within the last few years. Safety measures that are exercised when changing an empty container include following a safety checklist and using SCBA (Self Contained Breathing Apparatus) for the procedure. A chlorine container repair kit "B" is available from the local fire department HAZ-MAT team. The worst-case scenario at the Somerset Borough WWTP would involve the release of the entire amount of chlorine from a one-ton container in 10 minutes. Usin g EPA assumptions, the distance to toxic endpoint would be 3.5 miles with a release rate of 110 pounds per minute affecting an estimated population of 2958. The alternative release scenario involves the failure or breaking off of the valve, possibly due to human error while making hose connections. Using this scenario with EPA assumptions, the distance to toxic endpoint would be 0.2 miles with a release rate of 4.65 pounds per minute affecting an estimated population of <20. The general accidental release prevention program is based on the following elements: - High level of operator training - preventive maintenance program - Use of state-of-the-art process and safety equipment Chemical - specific prevention steps include the use of self contained breathing apparatus (SCBA) worn by the operators during connection/disconnection of chlorine supply and the presence of chlorine leak detectors. No accidental releases of chlorine have occured at this facility in the past five years. Our emergency response program is coordinated with and approved by the Local Emergency Planning Committee and has been reveiwed by the State Emergency Responce Commission. The amount of chlorine stored on site has been lowered in order to reduce accidental release possibilities. |