An accidental chlorine release by Bloomington Utilities on Wednesday did not harm Clear Creek, said John Langley, acting director of Public Works for the City of Bloomington.
The City sent a press release Friday announcing that a “higher level of chlorine than is optimal” was released into the stream from the Dillman Road Wastewater Treatment Plant.
However, after checking the stream and fish living in it, Langley said there was no damage done.
“It’s hard to find a word to describe how small this was,” Langley said. “Nevertheless, it happened, and it violated the limit, so we’re telling people about it.”
The City alerted the Indiana Department of Environmental Management, which asked for a report and has not taken further action.
The City’s Utilities Department is still conducting an in-house investigation to ensure that another accident doesn’t happen, Langley said.
The wastewater treatment plant uses chlorine to sanitize the water and ensure that what is released back into the stream is free of E. coli.
The plant has intentionally raised the level of chlorination at times to try to disrupt the egg cycle of “filter flies,” which hatch and live in the treatment system’s filters, Langley said.
One operator checked the chlorine feed pump that feeds into service water — water that has had waste removed, but is not drinkable — and raised the chlorine level twice, Langley said.
The operator didn’t tell the next shift workers the water was more chlorinated than usual before it was released into the creek.
“It was a minor accident that had a less-than-optimal outcome for us,” he said.
The limit for chlorine in a stream is 0.1 parts per million, Langley said.
Drinking water, in comparison, must not have less than 0.5 parts of chlorine per million of water, he said.
So, the City’s breach of the chlorine limit and subsequent announcement was a result of tight regulations, rather than a danger to the environment, Langley said.
“Our goal is to be completely transparent and tell the community about it,” Langley said.
