Annmarie Throckmorton, M.A.
- Jul 3, 2018

Subsidence

Early on in my ownership of the house at 1313 Towanda Avenue, Bloomington, Illinois, I noticed that the ground was rapidly subsiding from around the fire hydrant in front. The iris bed that I planted there kept getting lower and lower, even as I kept adding more soil there (a sand/soil mix added on top of irises will settle down under their rhizomes when it rains.) It seemed almost comical until I began to think about what the underlying cause might be. Even my backyard had unnatural depressions that regularly "consumed" the soil with which I filled them. People commented on how uneven my lawn was. I and my elderly friends were unable to walk across my lawn, but then we are all kind of unsteady even on a flat surface, so what are you going to do? Well, I did two things to solve the problem. Since I live near the top of a broad, high hill, I thought the problem might be natural slumping of the hill due to gravity, so I drove in rebar stakes along my downhill property line, at two foot intervals down to a two or three foot depth. This had some good effect, and it made a good barrier against which to build my natural wood raised flower beds, pretty and effective. (Years later my yard is flat and quite high.) But the front yard subsidence continued. Since this is not limestone country, I thought a natural sinkhole was unlikely, which left the most likely culprit to be underground water erosion, perhaps a leak somewhere in the public water system. Long story shortened by several years, my telephone and letter complaint campaign to the City of Bloomington eventually brought them to the discovery of a broken turn-off valve on the water intake to house next door. When they fixed that, my land stopped subsiding.