My sister pointed out to me that before the Great Chicago Fire, Michigan Ave. ran along the shore of Lake Michigan. But after the fire, all the rubble was simply shoved/dumped out into the water, changing the contours of the lake. Lake Shore Drive is basically built on the remains of pre-Fire Chicago. This clearance was necessary in order to rebuild the city.
After hearing somebody on TV ask, What'll we do with all the debris we'll have to clear to rebuild New Orleans? her idea was, Bulldoze it all into the lowest-lying areas of the city, tamp it down real hard, then build over the top of it. Maybe you could wind up with a city not so prone to flooding.