CLINTON — Greenery will start appearing on the Clinton Coal Gas contamination site owned by Alliant Energy as the company works to complete its work on the site in the next two years.
Alliant spokesperson Justin Foss and Manager of Environmental Services Jill Stevens said the company plans to remove concrete from the roughly 130-yard section along First Street and replace it with bushes and trees.
This will create a barrier between the site, located on Clinton's river front between Fourth Avenue North and Second Avenue South and Riverview Park, which borders it to the east.
Alliant uses the area to store its poles and other equipment, creating an unsightly neighbor for Riverview Swimming Pool.
"This area is a little unpretty," Stevens said. "But it's part of the current use for the site."
The company is working with Trees Forever to make the area more aesthetically appealing. Trees and bushes could be planted as soon as this fall and if not, would be in place by spring, she said.
Work on the site has been ongoing for more than 20 years and cost more than $12 million. The 7.9-acre site was home to a manufactured gas plant from 1869 to 1952, which left pockets of coal tar contamination.
From 2005 to 2007, Alliant removed 120,000 tons of soil contaminated with coal tar, lead and polychlorinated biphenyls.
The Environmental Protection Agency gave oversight of the land to the Iowa Department of Natural Resources in last fall.
The site doesn't present a risk to anyone in the area, Stevens said, but some work needs to be done before the Department of Natural Resources will say Alliant no longer needs to monitor it.
"You never really get them completely clean, but you get them to an acceptable level," Stevens said.
While the active remediation work is complete, residual contamination remains in the groundwater and some surrounding soil. Some of it is below the buildings that currently sit on the property.
"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."