 The data stated that from 1954 they released 100,000 tons of PCB into the environment, and that the sludge contained PCBs in concentrations as high as 50%.In 1989, during construction near the Zilwaukee bridge, workers uncovered an uncharted landfill containing PCB-contaminated waste which required $100,000 to clean up.Much of the Great Lakes area were still heavily polluted with PCBs in 1988, despite extensive remediation work.