"It's kind of like Elmer's Glue in the ground. It's sticky and it's just sitting there. It's hard to say how much is down there. Until we start digging we don't know," said Stevens. "We can't get to it, but we can keep in from being disturbed."
Dozens of monitoring wells dot the property so Alliant can examine the level of contamination and report it to the DNR twice a year.
The city of Clinton also recently took some steps to ensure no contamination is disturbed without Alliant and the city being the wiser.
The City Council instituted a no-fee right-of-way permit for the area surrounding the site that will allow the city to inform Alliant when someone is digging. It will also inform the person performing the work that they could potentially encounter some contamination.
Alliant hopes to complete its work monitoring the site by early 2015.
Once the DNR determines Alliant's work on the property is complete, a covenant will be placed on it that would prevent it from being used for residential purposes and would also prohibit any water wells from being dug on the site.
"It's something that started in the 1800s and is almost complete," Foss said. "It's the start of a new chapter."