Osceola Water Plant - Executive Summary |
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EXECUTIVE SUMMARY 1. Accidental release prevention and emergency response policies: In this water treatment facility, we handle chlorine that is considered hazardous by the U.S. Environmental Protection Agency (EPA). The same properties that make chlorine valuable as a disinfectant also require observance to certain safety precautions in handling chlorine to prevent unnecessary human exposure, to reduce the threat to our own personal health as well as our co-workers, and to reduce the threat to nearby members of the community. Our policy entails the intent to adhere to all applicable Federal and state rules and regulations. Safety depends upon the manner in which we handle chlorine combined with the safety devices inherent in the design of this facility. It is also dependent on safe handling procedures and the training of our personnel. Much of our emergency response program is based upon the procedures established in the Wallace and Tiernan Operation and Maintenance Manuals prep ared for this facility and chlorine safety information from the Chlorine Institute. The Water Plant will rely on community emergency responders for any release. The emergency response plan includes procedures for notification of the local fire authority and notification of any potentially affected neighbors. 2. The stationary source and regulated substances handled. 7 The primary purpose of the Osceola Water Plant is to clean and disinfect water to be used by the residents of the City of Osceola and rural water customers in Clarke county and Southern Iowa Rural Water Association (SIRWA) for potable purposes. Chlorine is shipped by truck to the plant in 2,000-pound cylinders (one ton). The chlorine cylinders are offloaded from the truck onto an open dock area. Both full and empty cylinders are currently stored outside on this dock area. From this location, one full cylinder will be brought into the chlorine storage room with a hoist crane. Both the chlorine storage room and the fe ed room are two separate rooms located a few feet away from the rest of the water plant building. Personnel access in and out of the chlorine storage and feed room is from outside the treatment plant building. 7 The regulated substance handled at this facility is chlorine. The maximum amount of Chlorine that can be stored at this plant is 6,000 pounds. 3. The worst-case release scenario(s) and the alternative release scenario(s), including administrative controls and mitigation measures to limit the distances for each reported scenario. 7 Worst-Case Scenario: The worst-case scenario has been defined as a 2,000-pound cylinder rupturing outside the chlorine storage room while unloading from the truck due to corrosion, impact, or construction defects. 7 The distance to the toxic endpoint of 0.0087 mg/l (8.7 mg/cubic meter) for the worst-case scenario is 2.6 miles. 7 Alternative Scenario: The alternative-case scenario has been defined as a release from process piping or valves ins ide the chlorine storage room. The maximum total release was 373 pounds. The maximum average sustained release rate was established at 12.7 pounds per minute over a 60-minute duration. 7 In average weather conditions, the distance to the toxic endpoint of 0.0087 mg/l (8.7 mg/cubic meter) for the alternative-case scenario is 0.53 miles. 7 Comparing alternate source assumptions, the model predicts that the release rate in the alternative case scenario will be limited by the flow through each of the 5/16-inch valve openings at the chlorine containers rather than flow through the piping. 4. The general accidental release prevention program and the specific prevention steps. This water treatment facility has worked to comply with EPA's Accidental Release Prevention Rule and with state codes and regulations. This chlorine facility was designed and constructed in 1985 and contains a separate chlorine storage room and a feed room. The ventilation system in the chlorine storage room con sists of an exhaust fan and a unit heater. Any released chlorine will not migrate directly to other interior portions of the water treatment plant because the rooms are separated from the rest of the treatment plant building. The existing chlorine gas detector in the chlorine feed room will be repaired and will be functional. The detector detects chlorine release as low as 1 parts per million and sounds an alarm in the water plant control room and appropriate response measures can be initiated. 5. Five-year accident history. We have not had an accidental release of chlorine from the covered process that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage. 6. The emergency response program. The facilities emergency response program is based upon responding to upset or malfunction conditions as described in the Operation and Maintenance (O & M) Manual prep ared for Osceola Water Plant. The Osceola Fire Department will be called (dial 911 or 515-342-3019) in the event of a chlorine release. We have discussed this program with the Osceola Fire Department and the Clarke County Local Emergency Planning Coordinator. 7. Planned changes to improve safety. Currently, there are no scheduled changes to the chlorine storage and feed system other than to repair the existing non-functional chlorine gas detector and connecting it to the control system telephone dialer. The detector will be set to detect chlorine levels as low as 1 parts per million (ppm) triggering audible alarms in the control room and have the capability to dial a series of numbers to reach the operator, superintendent, police, and fire department, etc. Since the facility is in operation for less than 24 hours a day, it is important that the plant superintendent and/or operator should be contacted to initiate emergency response procedures should the alarm sound. The entire chlor ine storage and feed system is proposed to be changed in the next 2-4 years in conjunction with a treatment plant capacity expansion to improve safety, reliability of operation, and redundancy. The proposed future feed mechanism will be an all-vacuum feed system with the vacuum regulator mounted on the one-ton cylinder. Planned future process improvements include new 1-ton container digital scales, vacuum regulators, automatic switchover module, automatic flow proportioning gas feed valves, automatic solenoid valves, and chlorine gas detectors. The early warning chlorine gas detectors in the chlorine storage and feed rooms and an alarm system in the central control room will be upgraded. |