The Pennsylvania Department of Environmental Protection fined 12 UPMC hospitals a total of $451,000 for violating the Solid Waste Management Act on Tuesday.

Inspectors from the DEP’s Bureau of Waste Management found that large amounts of untreated regulated medical waste — such as dressings, bodily fluids and needles — were sent to Waste Management Inc.’s Monroeville landfill, according to a DEP release. Regulated waste must stay separate from non-infectious waste and carry identifying labels before a facility sterilizes and disposes of it.

“UPMC has been working diligently to educate all staff about proper waste disposal and to ensure that all disposals are in compliance with regulations and DEP guidelines,” UPMC said in a statement.

Operators at the landfill notified the DEP after noticing medical waste among trash sent from UPMC facilities. The notification prompted a two-year investigation by the DEP of several UPMC facilities and two Allegheny Health Network hospitals, in which DEP inspectors discovered more instances of improper labeling, storage and handling of regulated medical waste by UPMC and AHN.

A contractor hired by the hospitals has removed the untreated waste and disposed of it at an authorized facility.

In light of the investigation, UPMC and AHN updated their training and policies. DEP inspectors have visited the hospitals following the investigation and will continue to investigate if there are additional violations.