A new report on conditions at Oak Brook's Graue Mill confirms what engineers initially thought when they examined the 161-year-old structure back in June.
According to the 114-page report shared with DuPage County Forest Preserve commissioners Tuesday, the mill along York Road is in good condition for a building its age but will need many repairs to preserve its safety and integrity for the long term.
Structural Engineer John Frauenhoffer told commissioners there are critical deficiencies in the structural support columns and beams that need to be fixed to ensure the structure's stability.
"It's got the same kinds of problems that buildings like this, that have been around for so long, have," Frauenhoffer said. "The good news is that it can be reinforced so that we can breathe decades more life into the facility."
While the interior and exterior masonry is sufficient, Frauenhoffer said several foundation stones have suffered cracks from the freeze-thaw cycle and will need to be replaced where flooding has caused rapid deterioration of walls and floors.
He also pointed out inadequate support and stability for the gear systems and the mill stone crane operations, which led him to declare the mill unsafe in June and to shut down milling operations for several weeks until an alternate grinder was purchased. The new grinder has allowed the mill to resume production of cornmeal as its primary source of revenue through the unofficial end of the milling season on Nov. 10.
The report also highlighted significant issues related to accessibility for all visitors.
The forest preserve district owns the historic mill, which was a stop on the Underground Railroad during the Civil War.
Kevin Horsfall, the forest preserve district's landscape architect supervisor, said engineers were called in June to review the integrity of the structure and the mechanical gear operations after repeated flooding of the mill and preventive maintenance found signs of significant stress on several mill components.
By the end of the year, Horsfall said, he hopes to present the board with alternatives and costs to address the concerns highlighted by the engineers. Following that report, he expects commissioners to discuss how to pay for the repairs, which may start at $20,000, and determine phased-in priorities.