Landfills owned by the nation's two largest trash firms have sued the state over a push to burn as much garbage as possible, rather than burying it.

Four landfills serving the metro area, owned by Waste Management and Republic Services, filed suit in May against the Minnesota Pollution Control Agency (MPCA) alleging that it is misinterpreting a decades-old Minnesota law that prioritizes burning the metro area's garbage to generate energy.

The agency fined the landfills $20,000 each this spring for accepting garbage that could have been burned at a local incinerator. One plant in particular, owned by Great River Energy in Elk River, regularly receives far less trash than it can handle.

About 20 percent of the seven-county metro area's garbage was dumped in landfills in 2016, while 25 percent was burned to make energy. The remaining 55 percent was recycled or composted.

Waste-to-energy facilities generally pull recyclable materials from the trash and grind it up before sending it into a giant fire, sometimes at a different location. Hennepin County's downtown Minneapolis facility burns the waste whole and removes metals afterward. The resulting ash, which is sent to landfills, is about a tenth the volume of the original garbage.

Yet controlling the flow of garbage is no simple task, because haulers typically choose where to take their loads. A 2012 MPCA report said haulers decide where to travel based on facility prices — the fee to drop off a ton of trash — as well as distance and company preference.

The MPCA announced its intent to begin enforcing the 1980s law several years ago after the Legislature asked for a report on how to achieve compliance. Waste Management challenged the enforcement in 2013, arguing the agency hadn't followed the correct procedures, but lost its case at the Minnesota Court of Appeals.

The landfills have now asked the courts to toss the MPCA's penalties. They argue the law is being misinterpreted to primarily hold landfills accountable, and that compliance is impossible without overhauling communication between landfills, haulers, incinerators and other trash-related companies.

Trash in the metro area is certified annually by counties as "unprocessible" based on the ability to sort and burn it. Waste Management said that means their workers don't learn whether a load of trash could have been burned until long after they accepted it.

"[Waste Management] is being penalized for a prior year's activity as measured against the operating capacity of a [garbage burner] over which it has no control," the suit said.

MPCA planning director Sig Scheurle declined to comment on the cases due to the pending litigation. In a response filed in a Waste Management suit, the agency said it regularly provided the company with updates on their "likely compliance status."

An attorney for Texas-based Waste Management also declined to comment. Kevin Bremer, area president at Arizona-based Republic Services, said in a statement that the company believes it is in compliance with the law.

"We've been working cooperatively for a number of years with MPCA on this issue, but we currently have a difference of opinion regarding compliance with the … statute," Bremer said.

Bremer added that the publicly owned facilities are running at capacity.

Processing generally costs more than dumping in a landfill, so public subsidies have helped keep some fees lower. Ramsey and Washington counties once used subsidies to lure business to a private processing plant in Newport, but recently bought it with the intent of requiring trash to be taken there.

Republic's lawsuit, filed through its subsidiary BFI Waste Systems of North America, says the MPCA is trying to unfairly benefit Great River Energy. It notes that the Elk River facility's fee per ton is higher than the market rate.

"The MPCA's enforcement action is being taken only to allow a private entity to command, at the expense of its private competitors, a larger share of the market than it has been able to obtain in the competitive marketplace," the suit said.

Great River Energy once benefited from Anoka and Hennepin County subsidies to help lower tipping fees, but no more.

The company's director of resource recovery, Tim Steinbeck, said the waste-to-energy facility is among the pricier renewable powersources the company's member owners purchase. He has previously said they are losing millions a year on the Elk River operation.

"Thus we need that $75 tipping fee," Steinbeck said.

Burning garbage itself is controversial because of the air pollution emitted by the facilities. Hennepin County's downtown facility is among the largest point-source emitters of nitrous oxide, lead, particulates and carbon dioxide in the county, according to MPCA data. Emissions were far below the agency's limits, however.

The petitions to review the MPCA's penalties were filed in May by landfills in Inver Grove Heights, Burnsville, Elk River and Glencoe. Three filed by Waste Management have been consolidated, with a hearing expected later this month.

Eric Roper • 612-673-1732

Twitter: @StribRoper