Designing a landfill is “basically building a bathtub,” said Government Affairs Manager at SKB Environmental Ryan O’Gara. Layers of liners, protective soil, and sumps and piping systems all over compacted clay and soil base form the basis for SKB Rosemount Industrial and C&B Waste Disposal Facility.
On Tuesday, April 1, Dakota County commissioners toured the site, hearing about the various contractors to the eventual closure of the site altogether.
On a busy day, the SKB Rosemount landfill receives well over 1,000 trucks, processing some 2 million tons of waste annually. Despite that massive quantity, “everything we take must be approved ahead of time,” said O’Gara. Every 10th truck is tested on various metrics from radioactivity to pH to reactions to water and air.
“All these fingerprints are to make sure what’s in the truck is something we can accept here,” said O’Gara.
Incoming trucks are even assigned coordinates as to where they dump waste so that they can be tracked if need be. If an object or specific load needed to be recovered, “we could go down within a few cubic meters and find it pretty quick,” said O’Gara.
Of the waste received by the SKB Rosemount landfill, most is contaminated soil, “by far,” said O’Gara. A specific source of contaminated soil is light rail construction that has brought well over 1 million tons of soil to the landfill. Other examples would be coal ash, foundry sands, and various industrial sludges received by the landfill.

Mining ash
One specific source of waste that the SKB Rosemount landfill has turned into a profitable income stream is ash from the Hennepin Energy Recovery Center (HERC). Located in downtown Minneapolis, the HERC receives waste from Minneapolis and other surrounding communities and burns it for energy.
Since 2004, the SKB Rosemount landfill has received ash and separates out ferrous and non-ferrous metals to be sold and recycled.
Burning metal may seem to make it disappear, but that material remains in the ash. Some 6-7% of ash by weight is recovered through a process of sorting ash that runs the gamut from magnets to hand sorting for copper and brass. Annually, the landfill recovers and sells 7-10 million pounds of non-ferrous metals and 3-5 thousand tons of steel.
“I’m sure Hennepin County didn’t think when they started sending us that ash all those years ago that it would be a mining stream,” said O’Gara.
The “mining” process undertaken at the SKB Rosemount landfill is contracted with Gem-Ash Processing. Rosemount and Pope/Douglas Solid Waste Management, located in Alexandra, Minn., are the “only ones in the country who do this,” said O’Gara. Many of the metals taken from the ash are shipped to Europe to be sold.

PFAS pre-treatment
In December 2024, the SKB Rosemount landfill began treating leachate for PFAS onsite. Leachate is the term for water contaminated from passing through other materials, in this case through the waste of the landfill.
While PFAS are infamously widespread, they are of particular concern for Rosemount. The three 3M dumping sites in Washington County that were the focus of the lawsuit that ended in the 2018 3M settlement fund are buried in a special cell at SKB. Up until recently, 3M itself would come to remove leachate from that cell and treat it internally, although, the cell’s pump has mostly “dried out by now,” said O’Gara.
The onsite PFAS water treatment plant (WTP) at the SKB Rosemount landfill is run by the Canadian company Altra Sanexen. The process for treating leachate differs drastically from the proposed plans for the WTP in Hastings, in part because standards are much, much stricter for drinking water. The target for pre-treatment is to remove 75% of all PFAS from water. The new national standards for drinking water for PFOA and PFOS—two of the most common types of PFAS—are 4 parts per trillion.
Within the cramped PFAS WTP at the SKB Rosemount landfill, an unassuming series of white containers, clear piping is stained black from the inside as engines whir. Operator Eric Gallagher downplayed the operation: “it seems pretty complex in here, but it’s pretty basic.”
Altra Sanexen uses a process called “foam fractionalization” to treat leachate. That process involves creating foam within the leachate which will naturally draw PFAS which normally accumulates at the surface of water. Creating foam on top of water “is basically just creating more surface area,” said O’Gara. Foam is skimmed off the water and sent into separation tanks multiple times which draws out, isolates and contains PFAS.
The separated foam is then reliquefied and combined with material O’Gara likens to baby diapers, which is then disposed of within the landfill.
The amount of leachate produced at the site is another concern. Open air cells produce more leachate because rain and snow fall directly onto waste. Processes like mining from the HERC’s ash that require cells to be open to the weather will naturally produce more leachate which then needs to be treated.
O’Gara openly admits that the services like onsite PFAS pre-treatment and ash mining are only available to the landfill due to its size and high revenue stream. Smaller landfills aren’t able to implement similar programs due to their prohibitive costs.

Future of the site
The timeframe of landfills is measured in decades. Events far out into the future like the eventual closure of the site are top of mind for O’Gara. Landfills are limited with how deep they can dig and how high waste can be piled, meaning that the capacity and lifespan of a site can be estimated with accuracy.
According to Dakota County’s 2018-2038 Solid Waste Master Plan, the facility’s lifespan was estimated to be “eight years for construction and demolition waste, 21 years for industrial waste, and 18 years for incinerator ash.”
Commissioners pondered sledding hills and greenways over the site after cells are capped with two feet of sand and planted with grass. Trees are generally not able to be planted because their roots are too deep.
O’Gara quipped about a future “Tour de Trash” over the site.
For more information on SKB Environmental and the Rosemount landfill, visit https://www.skbinc.com