In the 1920s, construction crews digging foundations for a handful of buildings uncovered water that appeared to be rushing through sand pockets, giving rise to a long-held myth that underneath downtown Oak Park, runs a mysterious "underground river."
The "river" theory was dispelled years ago, formally in the local press by a well-known River Forest geologist in the 1950s. But talk of water under downtown has resurfaced in recent years, notably due to construction of the RSC condo and retail project in the 1100 block of Lake Street, and development plans in the works for the Bank One lot.
Starting around 1925, the rumor grew out of a spate of ground breakings for various downtown area buildings: The Marshall Field building at Lake and Harlem; the Oak Park Club, at the southeast corner of Oak Park
Avenue and Ontario Street; and what is now the Forsyth building (which houses Community Bank) at Forest Avenue and Lake.
Water and sand were found a second time at the Community Bank site during excavation for an addition in 1952. Shortly thereafter, the Oak Leaves published a story, titled "Geologist unveils underground 'river' mystery." In the article, River Forest geologist Isabel Wasson (one of the first women to have a degree in petroleum geology) said the sand could be explained as the remains of the ancient glacial "Lake Chicago" beach. The lake, which existed over 12,000 years ago, created Oak Park's well-known continental divide, the high ridge that runs along Ridgeland Avenue, and through parts of River Forest and Forest Park. Construction crews at the time believed the water was moving, Wasson said, because when digging a hole in saturated sand, water flows into that hole.
"The so-called underground river, revealed by excavations in Oak Park, is not a river running below the ground, but is water filling the porous spaces in a long, narrow sandbar which diagonals across Oak Park," Wasson explained at the time.
Oak Park Village Engineer Jim Budrick, who said he occasionally gets some inquiries about the mysterious "river," said downtown simply seems to have a particularly high water table. All groundwater west of the divide, or "ridge," runs toward the Des Plaines River, and everything east, to the Chicago River and Lake Michigan. As it flows off the ridge toward the Des Plaines, Budrick said, a portion of it simply "finds its way geologically underground" to downtown, where water and sand can be found 12-14 feet below ground.
Budrick recalled encountering the water and sand a couple of times: When the village was installing a new sewer along Lake Street, crews went down only 8-10 feet, and he said the experience became akin to "digging in a beach." Underneath the Walgreens store that formerly sat on Harlem Avenue near Lake Street, which was removed to make way for the Shops of Downtown Oak Park (roughly where Pier 1 is located now), Budrick said there was a very deep basement, where the owner had to run a sump pump 24 hours a day.
Budrick acknowledged the soil just below ground can be quite sandy and that water can run through it "rather rapidly." But, he said, the water never looked much like a river to him.
"I've worked with the village for 26 years, and we've never hit any moving water in that area," he said, adding that though the "ridge" has contributed to flooding issues for northeast Oak Park homes, the water in downtown hasn't caused many problems.
The 'river' rises again
Construction crews, however, have had to cope with the "river" again in recent years. This is not due simply to the fact that there are more buildings going up in the greater downtown area (the sandbar runs in part from Oak Park Avenue all the way down Lake Street), but because underground parking is being incorporated into more developments, said Village Development Services Director Mike Chen.
"There's been an awareness [of the water] in downtown for a long time, but people are coming into contact with it more," Chen said, adding that some who cope with the geological conditions of downtown still call the phenomenon a river.
Chen said he's observed water at the construction site of RSC's 7-story condominium and retail development on Lake Street, which is to include underground parking; pockets of stagnant water can still be seen in the large hole excavated for the project.
Chen said the water "seems to have some flow to it," but he clarified, "this is not the Mississippi River drifting past the back door. This is not a raging river. It's water that is something a little less than standing if you encounter it," he said.
The water is not too troublesome (though a couple buildings in downtown do occasionally have flooded basements), as long as you're aware of its existence before you start building, he said. RSC is planning to install a form of drain tiling to prevent flooding. Sometimes, Chen said, it's even possible to use the water to your advantage. Before he was hired at village hall, Chen worked on construction of the 31-story World Trade Center in Miami. For that project, when a large amount of ground water was uncovered, crews simply used the excess water to mix cement for the foundation.
"It's important that once you get into the ground, you're not surprised, and have to scramble to make changes," he said. After RSC's experience, Chen said he tipped off architect John Schiess, who's planning a condo project at the Bank One lot downtown, to become aware of the "subsoil conditions." That condo project is expected to also include underground parking. Schiess said, through testing, he's already found water (which some in the area have already dubbed an "underground stream").
For other projects in downtown, however, the water hasn't had, and won't likely have, an impact. Tim Hague, president of Taxman Corporation, said despite the water in the old Walgreens basement, he doesn't recall having any problems with building the Shops of Downtown Oak Park. Those buildings, however, don't have basements or feature underground parking.
Also, though Whiteco's apartment and retail complex at 14 stories is rather large for a downtown building, Chen said he would "almost be surprised" if the company hits the water table at all.
And, despite what some may say, Chen adds, it's literally quite certain that, "Downtown is not washing away with a river."