Site A/Plot M Disposal Site

The Site A/Plot M Disposal Site is located within Red Gate Woods and situated on the former grounds of Argonne National Laboratory and its predecessor, the University of Chicago Metallurgical Laboratory in Cook County, Illinois. It is part of the Palos Forest Preserve of Cook County. The site contains buried radioactive waste from contaminated building debris, and the Chicago Pile-1, and Chicago Pile-3 nuclear reactors. "Site A" was an early Manhattan Project code for the facility. "Plot M" was the code name used for the disposal ground.

Source: Wikipedia