State and local police are investigating how more than 200 gallons of tar-like sludge ended up in the parking lot of a state sewage treatment facility in Somerville.
Michael Hornbrook of the Massachusetts Water Resources Authority says it appears someone dumped the material on their site illegally.
"We hope testing will reveal the source. We're also working with the Somerville Police Department to see if there are any cameras in the area that can also help identify any trucks that were in the vicinity in that time frame," Hornbrook says.
Early field tests show the substance is not hazardous.
This program aired on October 8, 2010. The audio for this program is not available.