Four times in the last 30 days, the City of Bloomington’s waste water treatment plant on Dillman Road was putting too much E. coli bacteria into Clear Creek.
Testing is done daily by water treatment plant staff, and it’s allowed for the E. coli limit to be violated three times in a 30-day period, department of utilities public affairs specialist Holly McLauchlin told The Beacon.
But if the E. coli limit is exceeded a fourth time, the city has to report it to the Indiana Department of Environmental Management (IDEM), she said.
The City of Bloomington announced the fourth E. coli violation, and its report to the IDEM, in a press release on Friday afternoon.
According to the press release, the daily limit for E. coli is 235 colony-forming units (CFUs) of E. coli bacteria per 100 ml.
Updated on Aug. 5, 2019 with additional information from the form received by IDEM from Bloomington: The level of E. coli CFUs measured by Bloomington, on July 23, was 365 CFUs per 100 ml, or 130 CFUs greater than the limit. Remedial action to be undertaken by Bloomington includes: relocation of two of four pumps; repairing the contact chamber rapid mixer; and investigating the departments sampling techniques location and process. According to IDEM Director of External Relations, Sarah Bonick,”IDEM is monitoring the situation and will ensure that the facility comes back into compliance.”
The cause of the violation, according to the press release, was a malfunction in the automated chlorine feed that’s used to disinfect the wastewater. Chlorine is used from April 1 to Oct. 31, according to the press release.
McLauchlin said chlorine is the last, optional step in treating wastewater, and it’s used seasonally, because E. coli thrives in warmer water.
Three violations with no report is allowed, McLauchlin said, because waste water treatment requires constant “tweaking and testing” to dial in the correct amount of chlorine to add. Chlorine kills living organisms, so if too much is added, aquatic life downstream could suffer. If too little chlorine is added, E. coli levels can be exceeded.
The fourth violation, McLauchlin said, prompted a review of the water treatment plant’s chlorine system, which revealed a defect in the chlorine pipe, which was then fixed. Responding to a question from The Beacon, McLauchlin said the fourth violation, requiring a report, did not come with a fine.
According to the press release, the recent violations of E. coli levels are the first in two years. The city’s utilities director, Vic Kelson, is quoted in the press release saying: “CBU is vigilant in maintaining and generally surpassing the most rigorous water and wastewater quality standards. This small aberration is the first in the last two years, and we detected and addressed it promptly.”