That’s more than a historical tidbit — it means the Star Wars creator will need a plan to safely unearth potentially harmful substances that date back to the Chicago fire. If Mayor Rahm Emanuel keeps his word, Lucas will pay for cleanup without help from Chicago taxpayers.

“Any design will account for existing environmental issues and be built accordingly,” an Emanuel spokesman said. “The mayor has been clear. No public dollars will be spent on construction of the Lucas museum.”

With Emanuel’s backing, Lucas is proposing a five-acre museum nestled on 17 acres of Chicago parkland just south of Soldier Field. But what’s buried below the surface of the site is nasty stuff. An analysis for the renovation of Soldier Field and the land around it more than a decade ago found potentially cancer-causing chemicals in the soil near the stadium, according to a site inspection report filed with the Illinois Environmental Protection Agency.

The source of chemicals can be traced back to ashes and debris from the Chicago fire of 1871 as well as other waste dumped along the lakefront up until the early part of the 20th Century. A parking garage south of Soldier Field serves as an “engineered barrier,” reducing the risk of human contact with the buried chemicals, state records obtained through the Illinois Freedom of Information Act show.

The Soldier Field analysis points to a hurdle Lucas needs to clear, but the cost of a cleanup is difficult to gauge for any single area until an analysis is completed.

“It could be a $50,000 problem or it could be a $2 million problem,” said Tony Dappas, an environmental consultant who analyzed the soil around Soldier Field for the Chicago Bears’ project manager during the stadium’s renovation.

The contamination discovered around Soldier Field is believed to be the byproduct from burning wood, coal and other materials. Embankments, parking lots and other paved surfaces around the stadium serve as barriers eliminating human exposure to the buried pollutants. Plans call for some of that area to be dug up as Lucas proposes moving 3,000 parking spaces underground. The project’s proximity to Lake Michigan also is a factor for environmental planning.

The city’s Department of Environment monitored the cleanup around Soldier Field during the stadium renovation but Emanuel has since eliminated the office in a cost-cutting move. The departments of Public Health and Fleet and Facility Management added environmental oversight.

The force is with VOA

Chicago’s VOA Associates recently was named local architect for the Lucas museum, a high-profile project for a firm that got millions of dollars in city contracts from the Daley Administration.

VOA CEO Michael Toolis is married to Chicagoland Chamber of Commerce CEO Theresa Mintle, who is both a cousin of former Mayor Richard M. Daley and Emanuel’s ex-chief of staff. Toolis’ firm was barred from doing business with the city while Mintle was Emanuel’s top aide, a job she left in March of last year. A spokesman for Emanuel said the city had no role in the selection of VOA for the museum project. Toolis declined to talk to us and Mintle didn’t respond to requests for comment.

Lucas is familiar with VOA because the firm did interior design work for his wife Mellody Hobson’s employer, Ariel Investments. Hobson told us her husband considered other firms but said she recommended VOA for the job.

Before becoming Emanuel’s first chief of staff, Mintle worked for the Chicago Transit Authority and Daley Administration. She and her husband were investors in the Park Grill restaurant in Millennium Park, the focus of a lawsuit brought by the city of Chicago related to the proposed sale of a concession contract. Mintle transferred her stake in the restaurant to Toolis just before taking the chief of staff job for Emanuel in 2011, a mayoral spokeswoman told the Sun-Times in January 2012.

At the CTA, Mintle helped tailor an early retirement program that allowed her to qualify for a pension without working the required number of years. After the Better Government Association reported on Mintle’s pension in October 2011, Emanuel’s office said she wouldn’t take advantage of the deal.

This column – a new regular feature called The Public Eye, appearing on the Chicago Sun-Times’ political portal Early & Often – was written and reported by the Better Government Association’s Brett Chase, who can be reached at bchase@bettergov.org or (312) 821-9035.