Clean-up has begun on the former Dairy Queen site in Nevada, where a leaking underground gasoline tank has contaminated soil and groundwater in the area.

The building, at 436 E. Lincoln Way, had been a Kerr-McGee Service Station from 1955 to 1982, and the Story County Board of Supervisors had expressed concern over the contamination at a meeting earlier this month.

The Iowa Department of Natural Resources had reported high levels of benzene and ethylbenzene in the contaminated area. Both chemicals are linked to cancer in humans following long-term exposure.

"We just wanted to make sure the proper steps are being taken to clean this up," said Supervisors Chairman Paul Toot.

Toot said the board sent a letter to the DNR following its Feb. 2 meeting, which prompted an hour-long conference call last week with the DNR to discuss the site.

Margaret Jaynes, Story County environmental health director, said there are a few confined spaces, basements and crawl spaces, that have a pathway for the vapors to potentially get in, but currently the levels in those areas are not concerning. The board was originally concerned with the impact the contamination could have on the house directly south of the site, but it was determined the yard should not be a problem because it is open air and not a confined space.

Over the next month, the site will undergo three clean-up procedures, where a high power vacuum will be used to extract the ground water and some of the vapors. The first session was completed several weeks ago and others will be completed later this month and again in March. The process is expected to remove the contamination and to introduce oxygen into soil.

The area will be tested again in about eight months to see if any contamination lingers.