Mansfield and company owner Russell W. Mahler later pleaded guilty in New Jersey District Court for dumping oil and chemical wastes into the Hudson River. Mahler also pled guilty to disposing of waste oil in the abandoned Butler Mine Tunnel in Butler Township, Pennsylvania, which in 1979 overflowed into the Susquehanna River. He was sentenced to one year in prison for the crime. The mine would later become a Superfund site. Mahler's firm had also received contracts to clean up some of the sites that it had previously contaminated with oil, including one in College Point. In 1982, New York City spent $2.5 million to clean up the company's Long Island City plant, located near the Greenpoint Avenue Bridge just north of Newtown Creek. In 1985, the city filed suit under the Comprehensive Environmental Response, Compensation, and Liability Act (a.k.a. the Federal Superfund Act) against the 14 companies who originally generated the toxic waste later dumped in the city landfills. In February 1983, nearly 3,000 55-gallon metal drums of waste were discovered inside the Edgemere Landfill. The drums were discovered in the "neck" area of the peninsula just south of the main landfill, when a tractor spreading dirt struck the drums by accident. While most of the drums were empty, many contained lead-based paint and resin. The drums were said to have been buried beginning in 1968, around 15 years prior, when there were fewer regulations concerning the disposal of chemicals. Following the discovery, the New York City Department of Environmental Protection began testing the air, soil, and ground water of the local area for runoff from the drums. That month, the landfill was designated a Superfund site. On May 18, 1983, the Toxics Project of the New York Public Interest Research Group released a report documenting the dumping of chemical toxic waste at city landfills from 1964 to 1979. The year-long study covered the Edgemere Landfill in Queens, the Pennsylvania and Fountain Landfills in Brooklyn, the Tallapoosa/Pelham Bay Landfill in the Bronx, and the Fresh Kills and Brookfield Avenue Landfills in Staten Island, based on unreleased DSNY internal records. It concluded that "hundreds of tons" of chemical wastes had been deposited at the landfills with the permission of the Sanitation Department, which had been legal until 1979, along with the illegal dumping of "millions of pounds" of toxic wastes such as waste oil. It also confirmed the use of oil at the landfills to control dust, which occurred weekly for six months in each year.