The former owner of a Portland recycling company with a history of fatal accidents and environmental infractions faces a possible stretch in federal prison for his role in mishandling oil spills at the plant.

Donald M. Spencer, the former president of the defunct Spencer Environmental Inc., will plead guilty Oct. 12 to a felony charge of mishandling used oil, according to his lawyer, Per Ramfjord, a partner at Stoel Rives LLP in Portland.

The government on Sept. 20 charged Spencer, 64, in a criminal information that accuses him of allowing his business to repeatedly overfill a waste pit in outer Southeast Portland and, when used oil was released, mask it with a spray-dispersant instead of containing it and mopping it up.

“The crime he is pleading guilty to involves spills of relatively small amounts of oil at the facility, which regularly handled used oil,” Ramfjord said. “These spills were largely confined to the facility itself and did not cause any significant environmental harm.”

Dwight C. Holton, the assistant U.S. attorney prosecuting the case, would not comment for this story, citing federal policy.

The government’s three felony charges accuse Spencer Environmental of illegally treating and disposing of two hazardous wastes — hydrofluoric acid, which is highly corrosive, and gasoline, which is ignitable — between 2001 and 2003 without obtaining permits from the Environmental Protection Agency.

Court papers indicate that Spencer Environmental, which primarily recycled motor oil and anti-freeze, unlawfully treated and disposed of the hazardous wastes from Scientific Imaging Technologies Inc. of Tigard, and Niemi Oil Inc. of Warrenton.

Spencer’s company was plagued with problems from its launch in 1994 to its sale in 2003 to Phoenix-based Thermo Fluids Inc. During that time, the Oregon Department of Environmental Quality cited the company several times for environmental violations.

The Oregon Occupational Safety and Health Division also cited Spencer Environmental at least six times for safety violations, including two fines for work-related deaths.

In October 1999, Thomas Cassell, 45, of Oregon City died after being pulled unconscious from a gasoline tank at a Spencer facility in The Dalles.

In June 2003, Timothy P. Smith, 22, of Gresham grew sick after he pressure-washed a tank at the company’s Southeast Portland plant. Smith died less than one month later, and his family, alleging that he inhaled hydrofluoric acid, filed a $7 million wrongful death lawsuit against the company.

Troubles did not end when Thermo Fluids bought the company. In March 2004, a welding accident sparked a four-alarm fire at the Southeast Portland plant, causing an estimated $3.5 million in damage. Oil runoff after the blaze killed 2,600 fish in nearby Johnson Creek.