A federal report on an oil sheen that appeared on the Cady Marsh Ditch in April revealed a local excavating company voluntarily cleaned up the potential source, but lab results later showed the business might not be to blame.
"Results from the fingerprinting analysis indicated that the oil from the R.A. Oros facility did not match the oil/sheen sample collected from the ditch near Ross Road," according to the U.S. Environmental Protection Agency report. "This indicates that there may have been additional sources contributing to the sheen downstream.
"However, the investigation was limited to these sample results due to the sheen disappearing after the response efforts."
According to a progress report issued Tuesday by the U.S. EPA, the sheen was reported near West 45th Avenue and Ross Road in Calumet Township on the Cady Marsh Ditch the morning of April 10.
Cady Marsh is a 7-mile drainage ditch traversing Calumet Township, Griffith, Highland and Munster.
The next day, investigators from the Lake County Hazardous Materials Team and the Lake Ridge Fire Department inspected R.A. Oros Inc., 4200 W. 45th Ave. in Munster, and discovered a sheen flowing from leaking totes containing diesel fuel and concrete-forming lubricants into the storm drain and Cady Marsh Ditch.
A police report was filed as a result of the investigation, and the company was instructed to place pads and a boom near the storm sewer to prevent any further discharge.
On the third day of the investigation, the EPA issued a Federal Notice of Interest to R.A. Oros. Tuesday's report said the company "elected to conduct the cleanup themselves."
R.A. Oros hired a contractor to erect additional pads and booms around the storm drain, deployed another boom in the ditch, plugged the storm sewer, constructed a secondary containment pad, moved the leaking totes to a containment area and removed the soil for disposal, the report said.
"Heavy rains have slowed cleanup activities and may cause significant flooding at the R.A. Oros site," according to the report.
The soils are awaiting disposal in an EPA-approved landfill.
R.A. Oros remains listed as a potentially responsible party in the investigation.
The report said the EPA will, "continue to work with (the Indiana Department of Environmental Management) and the local responders to ensure the cleanup is done correctly."
Jacob Hassan, on-scene coordinator for the U.S. EPA on the Cady Marsh investigation, was not available for comment Tuesday.
Calls to R.A. Oros seeking comment were directed to Valparaiso attorney Ethan Lowe, who was not immediately available for comment Tuesday afternoon.