Water Pollution Control Facility - Executive Summary |
|
City of Greeley Water Pollution Control Facility Risk Management Program PROGRAM 2: EXECUTIVE SUMMARY 40CFR ' 68.155 Executive Summary a) The City of Greeley Water Pollution Control Facility (WPCF) accidental release prevention policy involves a unified approach that integrates advanced technologies, standardized operating procedures, personal training requirements, self-auditing and recordkeeping procedures, and a top-down management commitment to safe chlorine handling practices. The Greeley Water Pollution Control Facility Emergency Response policy involves utilization of, and cooperation with off-site responders to address potential chlorine-related issues. b) The Greeley Water Pollution Control Facility is located in Greeley, Colorado along the Cache La Poudre River. The facility receives and treats all wastewater from residential, commercial, and industrial dischargers that are within the City's service area. The facility has a disinfection building that maintains one-ton chlorine containers, three chlorinators, vacuum piping, and various safety equipment. All electrical panels are located in a separate room in the disinfection building. An inventory of six one-ton chlorine containers is regularly maintained on-site in the dedicated disinfection building. The facility operates 24 hours per day, 365 days per year. At least one plant operator is always on duty and addresses alarms and monitors overall facility security. Plant operators and maintenance mechanics have been trained and certified in the operation and maintenance of the chlorination equipment. Only incidental (i.e., known and immediately controllable) chlorine-related events are handled by plant staff. Local hazardous response personnel respond to all other emergency events. c) The facility performed the required off-site consequence analyses ("OCA") for the agency-defined "worst-case" and "alternate" re lease scenarios. The facility utilized the OCA guidance for chlorine published by the United States Environmental Protection Agency ("EPA") in the Risk Management Program Guidance for Wastewater Treatment Plants (40 CFR Part 68). The worst-case release must assume the catastrophic release over ten minutes of the entire contents of a full one-ton container of chlorine, certain specified atmospheric conditions and the failure of all active mitigation systems. As permitted by the guidance, the facility assumed that the concrete disinfection building would provide a degree of passive mitigation by slowing the release of chlorine gas to the atmosphere. Applying the guidance, and assuming an obstructed ("urban") landscape, the facility determined that the defined worst-case release scenario would have an off-site toxic endpoint of 0.9 miles, potentially affecting an estimated residential population of 1500 individuals. (The toxic endpoint is identified as the maximum airborne concentr ation below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action.) The facility is also to identify an alternate release scenario that is more likely to occur than the worst-case scenario, but still result in an off-site toxic endpoint. A number of potential alternate release scenarios were considered; none was deemed reasonably expected to have an off-site toxic endpoint. The scenario with no offsite impact that was most probable to occur involves the rupture of the flexible connection (pigtail) to a one-ton chlorine container, possibly due to the manipulation of the connection when hooking up a chlorine container or the improper movement of the container via the overhead hoist that results in the container hitting the connection and causing a rupture. In this case, the rupture of the 5/16 inch connector tubing would result in a chlorine release of 15 lbs./minute. A chlorine scrubber that is designed to safely contain and neutralize the contents of a full one-ton container is located adjacent to the disinfection building. The scrubber automatically starts once the chlorine detector is activated. The mitigation and safety measures that are in place should eliminate any release of chlorine in case of a pigtail rupture. Therefore, considering the above scenario, there would be no offsite consequences. d) The Greeley Water Pollution Control Facility accident release prevention program is based on the following elements: Advanced process and safety equipment; A chlorine gas detector alarm in the disinfection building that triggers at concentrations greater than one part per million. (The alarm system will alert the plant operator on duty via a personal pager, a flashing light located on the top of the administration building, an audible horn located at the disinfecti on building, and the facility's computer control center); Standardized operating procedures; Training of plant operators and maintenance personnel in the chlorine process; Preventive maintenance program for chlorine process equipment; Hazard review of chlorine process equipment and procedures; Auditing and inspection program; Investigation program (which will investigate future incidents that could reasonably result in a chlorine release); and Personal protective equipment, including self-contained breathing apparatus. e) No accidental releases of chlorine have occurred at the Greeley Water Pollution Control Facility in the past five years. f) The Greeley Water Pollution Control Facility Emergency Response Program utilizes local hazardous response personnel to respond to emergencies at the plant. The Weld County Office of Emergency Management with the Union Colony Fire & Rescue Authority (UCFRA) is in the process of reviewing the program. All personnel will review these procedur es on an annual basis. The program consists of periodic discussions and exercises with the UCFRA emergency response team. A chlorine "B" kit for one-ton containers is also maintained and kept on the plant site for use only by the emergency response team, if it is ever needed. g) The Greeley Water Pollution Control Facility has implemented several changes in its chlorine process, including the purchase of a new chlorine gas detector (that will have a continuous chlorine concentration readout scale and which can be mounted outside where the operator can safely monitor what is going on inside the chlorine room), and the use of checklists for chlorine deliveries and weekly maintenance inspections. Additionally, all plant supervisors have completed STOP (Safety Training Observation Program), which is designed to enhance employee awareness about performing their jobs in a more safe manner and to how to recognize potential safety hazards. The facility also has a chlorine scrubber that is designed to safely contain and neutralize the contents of a full one-ton container. Adding an uninterrupted power supply unit to protect the chlorine detector is planned for 1999 or 2000. |