For drivers on Interstate 35W, Burnsville offers a dull vista of barges, billboards and what looks like 140 acres of snow-dusted prairie along the Minnesota River.

City officials once thought it would be an outdoor amphitheater and now dream of an attractive mixed-use development. But about 5 million cubic yards of trash keeps getting in the way.

Hidden under dirt and grass sits the highest-risk landfill in Minnesota that has not entered the state’s program to clean and monitor such sites.

The Minnesota Pollution Control Agency and the head of the U.S. Environmental Protection Agency say the former Freeway Landfill must be cleaned up.

The future of the landfill, which stopped taking trash 25 years ago, has been delayed by negotiations between the landowners and MPCA officials, who disagree on what’s required to fix the site. The negotiations have gone on so long that the EPA recently stepped in and imposed a June 30 deadline. If the sides can’t agree on how to handle the landfill by then, the federal agency will come in and clean it up.

“Really nobody in Minnesota would want that,” said Steve Mielke, Dakota County’s director for physical development. “They basically go in and make a fix, and they basically sue anybody that ever had anything to do with that landfill to recover the costs.”

For the MPCA, closure of Freeway Landfill, home to hundreds of cubic yards of battery casings and nearly 450 tons of by-product from aluminum recycling, would be a major accomplishment. Two decades ago, Minnesota created the Closed Landfill Program to handle the cleanup and long-term care of 112 landfills across the state. The program has prevented groundwater pollution and reduced the release of methane.

Only three of the 112 landfills have not yet entered the program. Freeway is about 50 times as large as the other two and is the only one where major remediation work is anticipated, according to the MPCA.

“This is a big one,” said Kirk Koudelka, MPCA assistant ­commissioner. “We want to make sure we do this once, we do it the right way, protect public health and the environment, and allow development, as possible.”

Ensuring safe water

The landfill’s proximity to the source of much of Burnsville and Savage’s drinking water increases the importance of cleaning up the site.

Residents drink water pumped from a limestone quarry next to the landfill. The quarry operation sucks up millions of gallons of water daily, keeping the water table so low that it does not mix with the buried trash next door, said Steve Albrecht, Burnsville Public Works director.

But eventually, the quarry company will stop operating — though that could be another 15 to 20 years — and the groundwater will rise and fill in the area, creating a lake.

“We need to know, number one: Will that groundwater table rise back into the level of the garbage? We don’t know the answer to that question yet,” Albrecht said.

A $47,000 study is underway to figure that out. Consultants are expected to wrap up the study by spring, he said, and it will determine the next steps for the landfill. The state could move the trash, add a barrier below it or just cover it up.

Digging up the trash and moving it would cost around $57 million, while covering it in place would be around $42 million, Koudelka said.

A contested closure

The landfill property owner and the state are negotiating over what is needed to safely close the site and how to pay for it.

“There’s history there about who thinks it’s closed, how it’s closed — is it closed?” said Jenni Faulkner, Burnsville Community Development director.

City staff said the property owners believe the landfill is already closed properly.

Michael McGowan, whose family owns the landfill, declined to comment on the discussions with MPCA.

“We would like to see the highest and best use of the land,” McGowan said.

Koudelka said MPCA will rely on the data from the study to determine how to best handle the landfill.

As for Burnsville, City Manager Heather Johnston said, “At the end of the day, we want the safety of the groundwater and the environment for our residents for the next 100-plus years.”

But city officials would also like to build on the site and complete their vision for the so-called Minnesota River Quadrant.

The quadrant, which currently includes the landfill, would become a “gateway to the city” with a golf course, waterfront promenade, medical campus and corporate offices. Property tax revenue from the new development could help cover the cost of remediation.

“It certainly is going to change the entire look of the city as you come in on 35,” Johnston said. “We want people to be drawn into those areas just as you would any other part of the city.”

But for now, Albrecht said, Burnsville can only wait: “The landfill obviously, depending on the closure method, is going to dictate if development occurs there sooner or later — or ever.”