COOS BAY — According to the City of Coos Bay, it was discovered last week that the recently constructed wastewater treatment plant in Empire experienced high fecal coliform bacteria counts in a sample that was taken.
The bacteria counts take approximately 24 hours to yield results. Fecal coliform are used as an indicator 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, as explained in a press release from the city.
Since the city can’t possibly test for every pathogen in the effluent, it tests for easily detectable indicator organisms. The assumption is that if the indicator organisms are killed then any pathogens are also likely killed during the effluent disinfection process.
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.
Currently the plant must adhere to monthly fecal limits, as opposed to daily. So at this time it is unknown if this incident will result in a permit exceedance, the release said.
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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 operators have investigated the cause and discovered that the plant operational settings were not correctly set for high flows.
The city received over five inches of rain from Saturday to Monday last week. As a result, the plant could not keep up with the high flows, the release said.
Plant settings have since been adjusted and it is not anticipated that this issue will occur when the plant goes into high flow mode in the future.