If future archaeologists look at the layers of waste in Cloquet's SKB Environmental industrial landfill, 2017 will be the "summer of dirt."
Since April, a steady stream of trucks has been traveling from Ashland, Wis., to the SKB Environmental (formerly Shamrock) landfill in Cloquet, each one filled with contaminated soil dredged from a Superfund site at the bottom of Chequamegon Bay.
The truckloads come from federal cleanup efforts to restore land and lake bottom sediment contaminated by a manufactured gas plant that operated near the site until the mid-1940s. Recently, SKB officials said they expect to bring approximately 120,000 tons into the landfill by sometime this fall.
Contaminated soil like the sediment from Chequamegon Bay is considered an industrial waste and is one of the materials accepted by SKB as long as the contaminants are within the guidelines, said SKB site manager Kyle Backstrom.
In addition, SKB President John Domke said, the Cloquet landfill is one of two in the Upper Midwest certified by the federal government to accept government-regulated waste such as the Superfund sediment. SKB Environmental is the closest certified landfill to Ashland, he said.
Before the company can begin taking new material, it needs to go through an extensive process to make sure the material meets its criteria.
"We have 30,000 pages of data we have to go through," Backstrom said as he pointed to a row of binders containing state rules and guidelines in the on-site office.
In short, SKB is not your grandparent's landfill. Landfills today are built to higher standards and are monitored by the state to prevent mistakes and problems of earlier landfills. The SKB Environmental landfill site also includes six wells that are tested quarterly by an independent company to make sure the water quality has not been compromised by anything leaching out of the landfill — as all water runoff in the Cloquet area ultimately ends up in Lake Superior.
"Any water and snowmelt that gets caught in the landfill is collected in a series of pipes in the leachate system and pumped to WLSSD to be cleaned," said Backstrom, explaining that water doesn't escape untreated from the landfill.
The SKB Environmental landfill encompasses nearly 60 acres of a 260-acre industrial site bordered by Interstate 35 and the Hilltop soccer fields on the north and south and 14th Street and Highway 45 to the west and east. The massive pit includes several businesses, including Ulland Brothers Gravel Operations, Carlson Timber, Sappi wood storage, KGM Contracting Gravel Operations and the landfill.
The landfill has been the subject of much controversy since it was first proposed in 2010, but arguments against the landfill were complicated by the fact that there was an existing Ulland landfill on the site, and conditional use permits issued in 1971 (for 140 acres) and 1975 (for 63 acres) allowed a landfill there. The city of Cloquet has since passed laws to prevent any new landfills or expansion of existing landfills within the city limits.
As it stands now, the SKB Environmental landfill is a 60/40 split, with 60 percent industrial waste and 40 percent construction and demolition materials, Backstrom said. There are nine cells, which are about 75 feet deep, with the first four feet being the preventive foundation, including a 60 mil HDPE geomembrane impenetrable liner. The landfill begins with a base comprised of two feet of compacted clay, then a layer of a special material topped off with the HDPE liner, followed by a layer of sand.
The liner is a somewhat flexible plastic material that is "plastic weld seamed" together to form what looks like a giant Tupperware bowl in the cell. When the seams are finished, they are tested with electronic probes pushed into the ground to look for any holes.
"They can even detect a small pinhole," said Backstrom.
Cells One and Two cover about 10 acres and are almost filled to capacity. Backstrom noted that about half of cell one is filled with debris from the flooding of 2012, when the landfill was made available for free drop-off for residents. SKB was also a major part of two city of Cloquet clean-up days for local residents in the years following the flood.
The majority of the contaminated sediment from Chequamegon Bay is being spread in Cells Three and Four. It will be intermixed with other waste, Backstrom explained. (Check out the video on the Pine Journal site.)
In addition to soil from the Wisconsin Superfund site, SKB also has accepted contaminated soil from a gas station in Cloquet.
Duluth's Verso Paper is a large SKB customer, and the landfill company has asked the city for several changes to its conditional use permit to accommodate demands specific to the paper sludge the company disposes of in Cloquet.
Several local businesses also utilize SKB's services.
"We have USG and Lambert's Auto Glass," said Backstrom. "USG is here multiple times a day every operating day we are open."
Another regular customer — Esko Fire Department — called during the interview. The department had done a controlled burn at a abandoned home recently and wanted to dispose of their burn materials at SKB, which they do several times a year.
TESTING 1, 2, 3
Backstrom explained how SKB decides if they will accept a material for the landfill or not. He took a random folder of a past situation as an example. Someone from the city of Cloquet called; they had discovered contaminated soil from a property they had owned at the time on Broadway Avenue and Cloquet Avenue
Backstrom said SKB sent the soil out to be tested to be sure it fit the guidelines of materials they are allowed to accept. The soil was tested for a long list of contaminants — metals, benzene, etc. The contaminants may be acceptable as long as they fall within the amounts allowed.
SKB also checks for the total leaching potential of the contaminants. Some soil contaminants are not a problem when they are dry, but adding water can cause them to leach into the leachate system.
An independent company conducts the testing and sends the results back to SKB along with a profile breakdown of the leaching potential to ensure that doesn't happen.
"If it meets our industrial solid waste management criteria, we can take it," said Backstrom. However, if it exceeds any one of the test points, SKB cannot take the material.
The Minnesota Pollution Control Agency makes surprise visits a few times a year, the site manager said.
They ask to see the paperwork and make sure everything is filled in to the last detail. They look for who transported the material, who generates the material, the volume that was brought in as well as other details.
The state has been to the site at least four times in the past year, Backstrom said. The county visits at least once a quarter and so does the city of Cloquet. They have the right to come on site without notice and they do.
"It is a pretty sophisticated process to accept waste," Backstrom said.