Twenty-four kilometres from Chicago’s downtown waterfront and iconic Navy Pier Ferris wheel, there is a little-known toxic waste dump. Located in the Southeast Side neighbourhood that once hosted the city’s steel manufacturing plants, the dump sits along Lake Michigan’s shoreline just north of Calumet Park’s popular beaches. Unlike many landfills, where human detritus piles up, this one contains material dredged from the Calumet River — the stuff pulled from riverbeds to ensure the commercial waterway remains navigable. It appears like a benign dry retention pond surrounded by barbed wire and fencing. But beneath the surface sit decades’ worth of highly toxic sediments, and like any landfill located next to where kids play, it has...