FBI agents helped officials from the Environmental Protection Agency execute federal search warrants beginning at 8 a.m. They stayed at the site until 4 p.m., looking through computer records and documents.
In a statement, a spokesperson for the EPA confirmed the agency's Criminal Investigation Division was executing search warrants, but declined to comment on the case because it is "an ongoing criminal investigation."
Beverly James, the chief engineer inside the plant, said the District is cooperating fully with the investigation, but they are unsure of what the EPA is looking for.
Environmental watchdog group Baykeeper told ABC7 says the investigation comes following an anonymous tip about two spills in 2007. The first alleges 2 million gallons of raw sewage flowed into wetlands during a maintenance procedure and the other was a spill of more than 1 million gallons.
A lawyer for the Sanitary District could not provide direct answers about the investigation.
There are no allegations that have been named, yet, the basis for the search warrant is in a sealed affidavit that we have not seen and we do not know what the nature of the allegations are," Kent Alm said.