Summary: Over the past month, the wastewater treatment plant in Empire has experienced sporadic higher than normal fecal coliform bacteria counts. Jacobs, the city’s wastewater operations and maintenance contractor, has evaluated the wastewater data and has determined the cause to be a process issue. While the plant is not subject to daily fecal coliform limits, it is subject to monthly requirements. The elevated fecal coliform at the plant will exceed monthly limits for March. Detailed Report: Over the past weekend, the wastewater treatment plant (WWTP) in Empire experienced higher than normal fecal coliform bacteria counts. Fecal coliform bacteria are used as indicator organisms to test the effectiveness of effluent disinfection in a wastewater treatment plant. While these organisms are generally harmless to us, they do live under the same conditions that human pathogens live. Because we cannot test for every pathogen in the effluent, we test for easily detectable indicator organisms. The assumption is that if we kill the indicator organisms then we most likely kill the pathogens during effluent disinfection. The WWTP has to meet effluent water quality limits that are identified in a permit that is issued to the City by the Oregon Department of Environmental Quality (DEQ). The cause of the increased fecal coliform count has been identified as a process condition that caused a higher than normal solids level in the effluent. This condition is being addressed by process changes and a settling agent has been added to limit carryover of solids in the effluent to improve water quality. The Ultraviolet (UV) disinfection system has been set at the maximum intensity to safeguard the water quality of the Bay. The treatment plant has returned to permit compliance and Jacobs continues to monitor water quality. Any questions can be directed to the City of Coos Bay Public Works Department at (541) 269-8918.
