St. Cloud Wastewater Treatment Facility - Executive Summary |
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Safety is the top priority at the St. Cloud Wastewater Treatment Facility (WWTF). In accordance with this, a Hazard Control Committee is in place for the St. Cloud Public Utilities (Water & Wastewater). This committee meets on a monthly basis to review accidents and make recommendations, discuss accident prevention and conduct safety audits at the two plants. The operators at the WWTF are taught to respect the hazards these chemicals represent and to treat them accordingly. The WWTF treats the wastewater for St. Cloud, Sauk Rapids, Sartell, Waite Park and St. Joseph. The last treatment before the wastewater goes to the Mississippi River is to chlorinate it. This is done to kill the majority of microorganisms in the wastewater. So the chlorine does not affect aquatic life in the river, sulfur dioxide is added to the wastewater to combine with the chlorine to form a more inert compound. The WWTF has no more than 18,000 lbs. of chlorine and 8,000 lbs. of sulfur dioxide at any one time. WORST CASE SCENARIO - The release of 2,000 lbs. of chlorine at the rate of 110 lbs./min. for 10 min. The math doesn't work because of the passive mitigation component. The release of the chlorine in an enclosed room would slow down the release of the chlorine gas to the outside atmosphere. This scenario also applies to sulfur dioxide. ALTERNATIVE SCENARIO - Transfer hose failure (closest to what could happen at the WWTF). The vacuum regulator attaches directly to the chlorine cylinder and the transfer hose follows. If the transfer hose loses its integrity, a valve in the vacuum regulator will close (shutting off the chlorine) due to the loss of vacuum. The only way for there to be a chlorine release would be if the vacuum regulator was knocked off of the chlorine cylinder. Again there would be passive mitigation to slow down the release of chlorine. This scenario also applies to sulfur dioxide. The WWTF complies with the OSHA PSM rule. This with the RMP rule, provide s a comprehensive safety program. Increasing inspections of the components of the chlorine and sulfur dioxide systems and using regulators that connect directly to the cylinder are important steps the WWTF has taken to minimize the risk of a release. There have been no reportable accidents in the history of the WWTF. It is stated in the procedure for changing chlorine cylinders that if the detectors go into alarm, WWTF personnel will evacuate the chlorine cylinder room and call the St. Cloud Fire Department HazMat Team. The HazMat Team and St. Cloud Emegency Management will take control of all activities from this point. The WWTF has trained with the HazMat Team which is one of seven state regional emergency response teams. Further training at the WWTF is also planned. |