City of Hermiston Wastewater Treatment Plant - Executive Summary |
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EXECUTIVE SUMMARY The City of Hermiston Wastewater Treatment Facilities have been providing safe and effective wastewater treatment for over 40 years while remaining committed to protection of the community and the environment. We willingly observe the most stringent industry safety precautions to prevent hazards in the workplace. City Management and Wastewater Operations staff have instituted procedures to ensure a safe working environment is maintained that emphasizes proper handling and containment of hazardous materials. The City's safety planning emphasizes prevention of the release of toxic substances to the environment. In the unlikely event of a release the plan also identifies in-house or community-based expertise which will be called upon to minimize impact to the community. The current Wastewater Treatment Plant (WWTP) is located a short distance north of the core of Hermiston along the Umatilla River in Umatilla County, Oregon. The Plant currently uses a secondary t reatment process consisting of rotating biological contactors (RBCs) with anaerobic sludge digestion. Disinfection of treated wastewater is accomplished through chlorination with chlorine gas. The WWTP falls under EPA RMP and OSHA PSM regulations due to the storage and use of chlorine gas for disinfection. The WWTP currently stores, at a maximum, 5000 pounds of chlorine in pressurized one-ton containers. No accidents associated with the storage of chlorine gas at Hermiston's Wastewater Treatment Facility have occurred in the last five years. In fact, there has never been a reported accidental release of chorine of any kind during the life of the current WWTP facilities (since 1980). An extensive Off-Site Consequences Analysis (OCA) of the worst case release scenario and alternative release scenario has been performed with the aid of EPA's RMP*CompT and other EPA guidance documentation. The following is a brief description of the OCA results. WORST CASE RELEASE SCENARIO Quantit y Released: 2000 lbs Release Rate: 200.0 lbs/min Release Duration: 10.0 min Wind Speed: 1.5 m/sec Atmospheric Stability Class: F Topography: Urban Distance to Endpoint: 1.3 miles Estimated Population within Distance to Endpoint: 600 Public Receptors within Distance to Endpoint: Schools, Residences, Hospitals, Recreation Areas, and Major Commercial, Office, or Industrial Areas Environmental Receptors within Distance to Endpoint: None Passive Mitigation Systems: None ALTERNATIVE RELEASE SCENARIO Quantity Released: 2000 lbs Scenarion Analyzed: Vessel leak Release Rate: 160.0 lbs/min Release Duration: 12.6 min Wind Speed: 3.0 m/sec Atmospheric Stability Class: D Topography: Urban Distance to Endpoint: 0.2 miles Estimated Population within Distance to Endpoint: 11 Public Receptors within Distance to Endpoint: Residences Environmental Receptors within Distance to Endpoint: None Passive Mitigation Systems: None Active Mitigation Systems: None The City of Hermiston WWTP falls under Prevention Program 3. The City has prepared an extensive and informative documentation package that covers all the elements addressed under Prevention Program 3 requirements. Hermiston provides extensive training for all employees who work on the chlorination process, including emphasis on stringent procedures for maintaining the integrity of the chlorination equipment. WWTP employees continuously monitor potential hazards that could effect the chlorination process. When a potential problem is identified it is scheduled for immediate correction. No changes have been implemented to the original chlorination process since the current plant was built in 1980. In-place safety plans will take every precaution necessary so that any future change deemed necessary will be correctly designed, constructed, and operated. The City of Hermiston has created a focused Emergency Action Plan (EAP) that will be followed in the event of an accidental release of chlorine at the WWTP. Employees are or will be trained in the procedures of this EAP to ensure its policies are quickly and effectively implemented in an emergency. Coordination with the local fire department and regional Hazardous Materials (HAZMAT) Team constitutes significant elements of this EAP. The regional HAZMAT Team for this area of Oregon is based out of Hermiston. A quick response featuring appropriate action is the primary goal for both the City and the HAZMAT team. In the near future, the City of Hermiston will consider minor changes to the chlorination process to ensure future safety for the public. These potential changes include upgrading chlorine detection devices, additional postings of emergency numbers and procedures, and general improvements to chlorine equipment. The City will also provide additional training for any employees that may require more experience with the chlorination process. We believe the outstanding safety record of the City of Hermiston and the City's WWTP related to chlorine gas will continue. Hermiston's focus will continue to be maintenance of a safe working environment for its employees and protection of the community. |