Investigators will return to the site of an oil leak that contaminated the Grand Calumet River in 1997 according to a story on www.nwitimes.com. Oil company BP will sink ground water monitoring wells to check for any remaining contamination in the soil. A leak mysteriously appeared at White Oak Avenue in Hammond from the six transcontinental pipes and eventually spread to the Roxana Marsh. The Marsh was part of a federal 80 million dollar cleanup recently. Amoco workers cleaned hundreds of cubic yards of tainted soil but found no source of contamination.