Waterlogged shale has expanded underneath the slab of Kansas University's Wescoe Hall, pushing upward and causing internal floors and walls to shift, a Topeka engineering firm has determined.
The report by Barnett, Stuart and Associates predicts that continued upward movement of the shale beneath Wescoe and the building slab is "probable."
Although sections of the slab have raised as much as four inches, the building is safe to occupy, said Jim Modig, KU's director of facilities planning.
"Other than the bad floor, it's still in good shape," he said.
University officials have monitored movement inside the 19-year-old humanities building since 1985. Maintenance workers drilled holes in the slab during spring break so engineers could obtain soil samples.
Wescoe's slab contains some conduits and drains, "but we have not experienced any damage that we're aware of," Modig said.
The Barnett report theorizes that shale bedrock expanded upward when tons of topsoil were excavated for Wescoe's construction, he said.
The shale expanded further as clays within the shale absorbed ground water, the Barnett report said.
The report has been forwarded for review to Finney & Turnipseed, a structural engineering firm in Topeka, and Slemmons and Associates of Topeka, the university's on-call architect, Modig said.
Their recommendations and cost estimates could be ready July 16, he said.
The university has several options to deal with the shifting Wescoe slab, Modig said. The least expensive would be to make cosmetic repairs and "level the low spots," he said.
University officials may consider removing the floor slab, excavating and laying down new fill. That option was used in the recent renovation of Snow Hall, which also was afflicted with moving floors, Modig said.
Although no ground samples were taken during Snow's renovation, Modig said he suspects moisture-laden shale was the culprit, given that Snow also is located on a hillside adjacent to Jayhawk Boulevard.
The most expensive option to fixing Wescoe's floor movement would be to replace the existing slab with a structural floor slab that would rise as the shale expands upward.
Modig said he could not estimate the costs of the options.
Movement under the slab appears to be the greatest between an old utility tunnel that runs diagonally beneath the Wescoe and a newer, adjacent utility tunnel.
The moisture content of soils in disturbed areas, such as beneath the tunnels, is higher and consequently "the material in between is subject to high moisture content," Modig said.
A moisture content of 13 percent is typical for an undisturbed area, but some soil borings were analyzed and found to have a moisture content as high as 22 percent, he said.