Wastewater Treatment Plant 2 Fecal Coliform Bacteria Issues, April 11

City of Coos Bay release – Summary: The new wastewater treatment plant in Empire experienced high fecal coliform bacteria counts in yesterday’s sample (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 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. 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 very high influent flows coupled with 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 had experienced an earlier failure; and during repair, one mixer was determined to have a damaged power cable.  It was sent to the factory shop for repair.  While the plant operates within permit with a single mixer out of service in any basin during normal flow conditions, the flows from the recent storm exceeded the capacity of the remaining mixer to treat the waste. In reaction to the high fecal and to protect water quality, the city has increased the dosage of Ultra Violet (UV) Disinfection to the maximum setting; and it is 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.