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Vic Kelson
City of Bloomington Utilities


Dillman Road Wastewater Treatment Plant Submits IDEM Report of July 4 Effluent Levels

Bloomington, Ind. - Treated wastewater discharged into Clear Creek July 4 from the Dillman Road Wastewater Treatment Plant (DRWWTP) exceeded the state permit limit of 0.06 milligrams per liter of chlorine for about 90 minutes, as operators responded to an equipment failure. This event was reported to the Indiana Department of Environmental Management (IDEM). No adverse impacts of the elevated chlorine levels were reported.  

In summer and fall, the Dillman plant utilizes chlorine to disinfect treated wastewater, then dechlorinates the water before releasing it into Clear Creek. This process prevents any E. coli and coliform bacteria that are not removed by the treatment process from entering the stream. During the early hours of July 4, a chlorine feed pump failed, activating a backup pump that dispensed chlorine at a higher rate than the original pump.  The change was not discovered until the water had passed through the contact chamber, where water is dechlorinated for 30 to 45 minutes before being released into the creek. Operators made adjustments to correct the problem as soon as possible. The report to IDEM documents an excessive effluent chlorine level lasting approximately 90 minutes. A visual inspection of the creek leading from the plant showed no evidence of adverse impacts.

Utilities staff are reviewing operating procedures and staff training to prevent a future occurrence.