Operators of Hagerstown's disabled wastewater treatment plant are expected to begin using chlorine today to disinfect the raw sewage that has been flowing into a Potomac River tributary since chemicals from an unknown source knocked out the plant on Friday.
The plant has been spilling 5.7 million gallons of raw sewage a day into Antietam Creek since one or more toxic chemicals killed the microbes that remove harmful germs in sewage.
Officials could not say how long it would be before the plant is operating normally. "We've never had to do this before," said Donald Barton, plant superintendent.
Officials identified a trio of common industrial chemicals - toluene, xylene and ethyl benzene - in the wastewater. Richard J. McIntire, spokesman for the Maryland Department of the Environment, said investigators are still trying to determine their source.
McIntire said the same chemicals apparently passed through the nearby Conococheague sewage treatment plant, operated by Washington County, though not in concentrations high enough to cause problems. Crews there reported the same chemical smell Saturday afternoon as detected at the Hagerstown plant.
"That means there's a potential that this may have been dumped in a couple of spots," McIntire said.