This week, the Army Corps finally withdrew its proposal to extend the landfill, due in part to Illinois state permits getting denied. "By denying the permits, then forced the U.S. Army Corps of Engineers to take a different look," Learner said.

The dump — known as a confined disposal facility — was constructed in 1984 to store polluted sediment dredged from the Calumet River and Cal-Sag Channel. When it reached capacity, the initial plan was to top off the 45-acre site and turn it over to the Chicago Park District.