dumping ground vs hazardous waste dump

dumping ground

noun
  • Any place where unwanted items are sent. 

  • A landfill. 

  • A presumably polyphyletic supraspecific taxon where species of unclear affinities are placed. 

hazardous waste dump

How often have the words dumping ground and hazardous waste dump occurred in a corpus of books? (source: Google Ngram Viewer )