CHARLOTTE, N.C. - Cancer-causing chemicals have been illegally dumped in Charlotte for the third time, officials said.
There are new concerns that someone started pumping PCBs into the city's water system months before it was first discovered.
The cleanup of the toxic sludge is a major cost to taxpayers.
Read our past coverage of the illegal dumping: Mayor on illegal dumping: 'Anything coming out of your faucet is safe'
There is an investigation that started in February when the dangerous chemical was found in the city's sewer system.
Utility workers made the latest discovery over the past few weeks.
They said the dangerous chemical started showing up in sludge at a waste water treatment plant.
Now city leaders said it could cost more than $1 million to fix the problem.
The city would normally ship out sludge to treat area farmland but they'll have to send the contaminated batch to a special facility and the cost is adding up.
"We're anticipating that this could cost easily a million dollars and more than that,” said Barry Gullet, Charlotte-Mecklenburg Utility Director.
They said someone did the same thing in the Greenville area last fall. In February someone dumped the chemical into a manhole behind a Charlotte business.
Later that month utility workers discovered a similar incident.
“We believe people doing dumping are doing it under the cover of a legitimate grease hauler,” Gullet said.
Police have been unable to find those responsible and they increased their reward for information leading to an arrest to $10,000.
'"It needs to be stopped," he said.
Utility workers said the water that's treated at the plant is shipped back out into the creek.
They've been testing it and say it is safe.
Also they said this facility only treats wastewater, so drinking water is not at risk.
Environmental experts said PCBs are dangerous because the chemical never goes away.
It was banned in the 1970s because it was linked to health issues, including cancer.
A multi-agency criminal task force led by Charlotte-Mecklenburg Police Department continues following up on any and all leads, and asks anyone with information leading to an arrest on these cases of illegal sewer system dumping to contact the Crimestoppers Hotline at 704-334-1600.
Drinking water in Charlotte and other water systems downstream of Charlotte was and is not affected by this incident.