By DUANE NOLLEN
The Oskaloosa Herald
MidAmerican Energy has been removing soil from a site at the intersection of South H Street and Third Avenue West this spring as coal tar residue was found there.
Officials from MidAmerican Energy and the Iowa Department of Natural Resources held an informational town hall meeting Monday evening to update residents on the work in progress.
Iowa DNR officials received word in May 2012 that a homeowner at 902 Third Ave. W. had experienced a differential settling of his home — there were cracks in the basement. Oskaloosa city officials dug some test trenches thinking that an old sewer line had collapsed; however, contaminated soil was discovered and MidAmerican Energy was notified, said Matt Culp of the DNR’s Contaminated Sites section.
Workers had discovered coal tar residue from a manufacturing gas plant located about a block away. The plant operated from the 1870s to the 1930s and converted coal into gasoline, said Jenny McIvor of MidAmerican Energy.
Soil and ground water tests were conducted of the area and a remediation plan was developed, Culp said.
Hydrogeologist Kevin Armstrong said researchers collected hundreds of soil samples for laboratory testing. A review of historical documents from 1917 showed no indications of any ditches, channels or storm sewers at the site. There was a lot of debris found in and above the contamination zone.
“The area was low-lying,” Armstrong said.
A lot of debris from a former garbage dump was in the area as well as dirt was used to raise the level of the land in the area. As the result of this past year’s drought, the water table had dropped and made the ground less stable, which resulted in the home settling, he said.
Armstrong said the findings of the research showed that the manufactured gas plant had discharged oily water into a ditch or sewer system. There was a 4-foot layer of contaminated soil that was covered by 10 feet of clean soil. The contaminated soil was removed.
There are “no current risks,” he said.
Culp said MidAmerican Energy had gained access and ownership of the property, isolated the clean-up area with fencing to keep people from falling into holes, and demolished a house and removed a trailer.
Culp said that soil, water and air sampling was conducted before the clean-up and will be done after the clean-up to ensure all contamination is gone.
Armstrong said that clean fill dirt is being placed on the property and it will be a green area. Forty-two semi loads of contaminated soil was sent to a landfill in Illinois and debris from the house was taken to the landfill in Mahaska County.
During a question-and-answer period, audience members were concerned about adjacent properties having contaminated soil. One person asked if it was safe to eat vegetables grown in a nearby garden.
“I would eat anything gardened and feel confident,” Culp said.
Some audience members asked if a neighborhood park and a nearby stream would be tested.
Culp said there are no concerns about closing the park.
McIvor said the clean-up of the property would be complete by the end of May or early June.
Culp said that another townhall meeting could be held after the soil remediation is complete.
Herald Editor Duane Nollen can be reached by email at firstname.lastname@example.org