City of Coos Bay release – Summary: The new wastewater treatment plant in Empire experienced high fecal coliform bacteria counts in yesterday’s sample, Tuesday March 26, (the test takes 24 hours to yield results). The cause of the high bacteria count was due to an equipment malfunction. The city’s wastewater contractor identified the source of the malfunction, and he is making repairs. Additional disinfection measures are in place until lower fecal coliform counts are observed. Detailed Report: It was discovered that the recently constructed wastewater treatment plant in Empire experienced high fecal coliform bacteria counts in the sample that was taken yesterday (the test takes 24 hours to yield results). Fecal coliform is 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. Since 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 Plant 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 Plant does not have daily fecal limits (only monthly); and at this time, it is not known if this incident will result in a permit exceedance. However, the city has elected to report this issue on a voluntary basis so that the public is informed and aware of the issue. The cause of the high fecal count was due to an equipment malfunction. The sequencing batch reactor (SBR) tanks (these are the tanks where the wastewater treatment takes place) has mixers. The mixers keep the solids in suspension so that they can be treated. The mixers are controlled by electrical relays. The relay boxes are located on the walkways on top of the SBR tanks. Condensation entered into the boxes and caused the relays to malfunction. The city’s Wastewater Contractor investigated the relay boxes to determine how moisture was able to penetrate the boxes. The cause has been determined and a repair is underway. In reaction to the high fecal coliform count and to protect water quality, the city has increased the dosage of Ultra Violet (UV) Disinfection to the maximum setting and also supplementing the UV with a disinfection chemical. These extra precautions will remain in place until acceptable fecal coliform counts are observed. The city reported this issue to the Oregon Emergency Response System (OERS). Any questions can be directed to the City of Coos Bay Public Works Department at (541) 269-8918.
