Because dirt is in demand, Dakota County has taken a significant step to make more of it available.
With a recent change to its soil ordinance, the county now allows “minimally contaminated’’ soil removed from development sites and road projects to be reused on commercial and industrial property.
Until now, the county had a black-and-white policy requiring soil with any level of contamination to be disposed of in a landfill.
That requirement was stricter than the state’s for minimally contaminated soil, and ultimately the county staff found it impractical to enforce and “unnecessarily costly for contractors and landowners to comply with,” said Environmental Manager Jeff Harthun.
The relaxed ordinance has been applauded in Burnsville, where 800,000 cubic feet of fill dirt will be needed to strengthen soils in an area near the Minnesota River where the city hopes to see future redevelopment.
“That amount of soil would cost millions of dollars to both excavate the bad soil and bring in the new soil,” said Burnsville Public Works Director Steve Albrecht.
Using slightly contaminated soil is likely to cost half as much as clean fill, increasing the chances for redevelopment, he said.
The soil will start coming to the area right away. Excess dirt from the Hwy. 13-County Road 5 interchange reconstruction, which is underway now, can be sent there, Albrecht said.
“Had the ordinance not changed, we probably would not have been able to use all the soils on Hwy. 13,” Albrecht said.
The city is not buying soil for the redevelopment area but is directing it to property owners willing to receive it, Albrecht said.
“We have some soil coming from the Fairview Hospital project right now. For the hospital expansion they have to do a considerable amount of grading. We were able to direct that there.” Fairview is expanding its Burnsville hospital and building a medical office building, parking ramp and skyway on its Ridges Campus at 201 E. Nicollet Blvd.
The Minnesota Pollution Control Agency labels minimally contaminated soil as “unregulated fill,” because “you can detect something but it’s below our regulatory threshold,’’ said Hans Neve, supervisor with the remediation division at MPCA. Minimal contamination means the soil must be free of solid waste, debris, material containing asbestos, stains and chemical odor.
The agency developed guidelines for using slightly dirty dirt because large volumes of it were being trucked to landfills when it could have been used at adjacent commercial or industrial building sites in need of a large volume of soil, Neve said.
“Think of hundreds of trucks driving out to a landfill to dump this stuff when it could be used two blocks down the street,” Neve said.
He sees little potential for harm to the environment from highly contaminated soil being passed off as minimally contaminated soil because landowners who accept soil from another location are extremely careful not to take in pollution. Also, if lenders are involved with the property, they will have controls to keep contaminated soil off the site, he said.
To police the ordinance and ensure that only minimally contaminated soil is reused, the county will make random soil checks at excavation sites. Typically, soil sampling and testing is done before any dirt is moved, Harthun said.
In the past, Dakota County regulated soils more closely than other counties because “we got a lot of soil from the urban areas coming down to the landfills. Enormous tonnages of contaminated soils have gone into the landfills over the years, some of it low contamination,” Harthun said.
For help in monitoring the re-use of slightly contaminated soil, the county will ask cities to watch for soil issues in their community development projects, Harthun said.
“Developers talk. When you maintain some level of regulatory presence, that becomes known out there.”