Sioux City Wastewater Treatment Plant - Executive Summary |
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Executive Summary The Sioux City Iowa Wastewater Treatment Plant process 12 million gallons of wastewater from the communities of Sioux City and Sgt Bluff Iowa, North Sioux City and Dakota Dunes SD, and South Sioux City NE. The objective of the wastewater plant is decrease the impact of the constituants of the waste, on the environment and human life. Chlorine is added to the secondary clarifier effluent between May 1 and October 31 each year. The treated water is eventually discharged to the Missouri River. Storage: Chlorine is delivered to the treatment plant in one-ton cylinders. By administrative control, a maximum of 4 one-ton containers of liquid chlorine is stored on site in the chlorine storage room or on storage rails just outside the room. Accidental Release Prevention and Emergency Response Policies At The Facility: The Sioux City Wastewater Treatment Plant Risk Management Program includes the following key elements to mitigate the effects of potential chlorine rel ease hazards. Chlorine detectors, Employee TRaining, PM Program, Chemical Right To Know, Aduditing and inspections and respirator training. Description Of The Facility and the Regulated Substances Handled: The facility is designed for 30 million gallons per day and handles ~12 millions gallons. The water flows by gravity into the plant where it is treated mechanically and biologically. A treated sludge results from the materials removed and after it is treated. The sludge or Biosolids is applied to farm feild for biological resuse. The treated water is finally chlorination and dischaared into the Missouri River. The worse case Senario and Alternative release scenarios: The worse case release scenario as postulated in the regulation (40 CFR 68.25) is the release of the greatest quanity (of chlorine) in a single vessel. The entire contents of this vessel are assumed to be released as a gas over 10-minute period. The largest single vessel at her treatment plant is a one-ton conta iner: therefore , 2000 pounds of liquid chloi\rine will be released as a gas over a 10mininute period. A release of this magnitude would only be possible if the shell of the container failed and the liquid chlorine formed a pool and vaporized over a 10-minute period. The likeihood of this type of catastrophic release is very minimal. According to EPA's model RMP*Comp (TM), using the rurual site option, the distance to the endpoint is 3.0 miles. There are 10,635 resisdent popultion along with hopitals, schools, within the 3 mile radius. The meteorological conditions associated with the worst-case release scernio, as prescribed in the regulation, is a wind speed of 1.5 meters per second (3.36 miles per hour) and very stable atmospheric conditions. The stable atmospheric conditions will limit the mixing of chloorine gas with the ambient air as the gas travels downwind from the point of release. The cloud formed by the chlorine release will grow in size and decrease in concentration as it travels downwind. General Accidental Release Prevenntion Program and Chemcical Specific Prevention Steps: The facility complies with EPA's accident prevention rule and all applicable state and local codes and regulations. The chlorine system is designed, installed and maitained in accordance with applicable codes and state law. The treatment plant maintains emergency equipment and procedures in the PSM and the hazardous response plan. The cylinders receive care in handling and are inspected when they arrive. The cylinders are inspected and filled according to all state and federal regulation by the supplier. Five Year Accident History: The Sioux City Wastewater facility has not had a release invovling chlorine that has required hospitalization, care of a physician or that has caused death, injury, property or enviornmental damage, evacuations or shelterings. Emergency Reponse Program: The treatment Plant has site specific Emergency Response Plans (ERP's), revised annually , that outlines employee proccedures in the event of an emergency. The facility's ERP includes specific procedures for emergency materials handling, planning, evacuation, contacts, reporting , and training. The facility has worked with the Sioux City Hazmat Team for chemical spills and releases. Planned Changes to Improve Safety: None |