The EPA take on this with some photos. Apparently during the late 1960s and early 1970s, the site was used for the disposal of paint sludge and other waste generated at the Ford Motor Company's Mahwah facility. The site was originally added to the National Priorities List of abandoned hazardous waste sites in 1983.
http://www.epa.gov/region2/superfund/npl/ringwood/
The past is a foreign country: they do things differently there.