Super-retailer Walmart has been slapped with $110 million in environmental fines after pleading guilty to improperly dumping pesticides — all of it returned by customers — into public sewers and landfills, creating a toxic nightmare.

The Justice Department’s Environmental Crimes Section told Secrets that it was the second-largest environmental criminal fine ever imposed in U.S. history after the $4 billion BP oil spill in the Gulf of Mexico.