City Council, January 28, 2020
An interesting issue that will get attention was presented by Ald. Bilotto regarding a sinking parking lot at 13101 S. Western Ave. (Dunkin Donuts). Resolution # 2020-006 authorizes and approves a geotechnical engineering service to drill in several places to find out the problem and how to remedy. A building sat on the property until the 80s and may have been improperly backfilled. The lot sinks a few inches every year and the City throws blacktop to the affected area every year, which is a band-aid solution.
Outside of the meeting, the subject matter of sinking parking lots led to a discussion prompting further research. Soil problems and moisture are indeed a cause. According to PavementSpecialties.com, “The soil under your parking lot needs to be properly compacted. If it isn’t, one bad freeze/thaw cycle could be enough to change the levels and balance, making your asphalt completely unstable.”
Furthermore, “Too much moisture, whether from weather or poor drainage, can cause soil erosion resulting in a sinking parking lot.” Our weather range of freezing cold to extreme heat further exasperates the situation. We will look forward to this unearthing discovery.
Present were Mayor Domingo Vargas, Clerk Randy Heuser, Attorney Cary Horvath, and Aldermen Annette Alexander, Fred Bilotto, Raeann Cantelo-Zylman, Candace Carr, William Cazares, Bill Fahrenwald, Tom Hawley, Dexter Johnson, James Klinker, and Mike Mech. Treasurer Carmine Bilotto, and Aldermen Kevin Donahue, Johnny Hill, Nancy Rita, and Alecia Slattery were absent.
This is an important subject for the city council to cover, study, and solve. A sinking lot can lead to a sinking hole, which can be very dangerous to anyone nearby at the time that the hole presents itself.
Close by there is another sinking area on Western Avenue. Between Dunkin Donut and Kline’s building, Western Avenue dips and is noticeable. This also should be examined. Imagine a hole materializing right on a main street.
Examining these kind of sinking areas can save lives, and at the very least, a very good study of why the area is sinking. Both areas are close to the canal. We won’t know for sure if that is a factor until we examine and study the area.
I too had wonderings and was fascinated with this, especially sinkholes, which is totally different than this. I wouldn’t think the canal would have anything to do with this since that is man-made. Blue Island is very hilly. Ald. Bilotto said it was a problem with backfill.
Anyway, I looked up sinkholes and according to LiveScience.com, they are caused by:
1. Little soil or vegetation over the limestone or other bedrock. Water from rain and runoff slowly trickles through crevices in the bedrock, dissolving it.
2. Areas where sand covers the bedrock. The sand filters down into openings in the rock, gradually causing the land surface to sink.
3. (Most dangerous) “The bedrock is covered by a layer of clay. Beneath this ground cover, water dissolves an underground cavern causing ground sediments to erode into the cavern from the bottom. The ground continues to crumble from beneath until only a thin layer remains between the surface and the underground opening. When that layer collapses, the sinkhole opens up suddenly, swallowing any structures on top.”
I have been a citizen of Blue Island for over 28 years. This issue of the sinkhole in the parking lot could be nothing but a bad infill job. However, after reading the comments from others, I would very much be concerned about Western Avenue itself. While I believe that drilling test holes is a good idea, I would recommend trying to find old water or sewer taps coming from the parking lot and drill a couple of test holes in the street.
Years ago, contractors did not always do the right thing. I would highly suspect the backfill when these old building were removed, was not done correctly. I don’t know when sewer or water supply lines under Western in this area have had any work done on them, however, I certainly believe they should be checked out.
As a major downtown contractor in Chicago, back in the mid-80s, I took the basement floor out from under 10 S. Wabash. This is one block from State and Madison, the heart of downtown. The building is now the Silversmith Hotel. When I worked on the building, the ceiling height in the basement was 5 to 6 feet. We cut the floor out to make the ceiling height 12 feet. What we found approximately 5 feet under the original floor was an old water supply line coming from the street. It had been capped off under the floor. It was still connected to the city water supply. It was leaking under the basement floor of the building. It had caused a void under the floor that in time would have caused the concrete basement floor to crack or give way. In time this would have undermined the foundation of the building itself. Sinkholes are not something to be ignored. It’s very important to find the cause.
Very interesting. Thank you for your experience. The impression I get from sinkholes is that they’re more nature-made but the parking lot problem could just be man-made.
You bring up a very good point about how contractors don’t always do the right thing. It reminds me of when some would dump harmful chemicals and contaminate either land or water. Sometimes we then we hear about cancer clusters showing up.