The site was proposed to the National Priorities List (NPL) on the basis of past disposal practices which included the direct discharge of wastewater containing such hazardous substances as chromium, zinc, and phenol into the Nashua River and the disposal of sludge containing such hazardous substances as chromium, pentachlorophenol, phenol, and 2,4,6-trichloropehenol into a number of unlined dispo