Back in June, I took the following photos. They show a sinkhole of some sort that appeared sometime between Friday June 11 and Saturday June 12. Why am I mentioning this now you ask? Well, that sinkhole made me think about how the infill was placed over the existing lake bottom. The lake bottom was probably made up of layers of soft silty material covering years of decomposing who knows what. This is the contaminated material that is going to have to be excavated as part of the site remediation. The rock infill was simply dumped on top of this material. I am wondering, why the area was not excavated to firm bottom prior to the placement of the rock infill, especially if it was going to have to be removed at some point anyway? Did this not create a rock sandwich? The rock infill is now sitting on contaminated material that may not be all that stable. The sinkhole that appeared back in June, may be a symptom of a greater problem that we have created. Is the rock infill stable enough to build on? I know that when you want to build on top of unstable lake bottom, you excavate that unstable lake bottom to bedrock, or at least some very firm ground. You can’t build on muck. My question is where did the material go on June 11/June 12? Can it happen again?
Figure 1 was taken on Friday June 11. No hole.
Figure 2 was taken on Saturday June 12. You can see the hole that has appeared. It is surrounded by orange cones
Figure 3 was taken Sunday June 13.
Fig 4Figure 4 shows a close up of the sinkhole.
The rain back in June created this.
The hole was eventually filled in. Right now, there is a backhoe that is digging holes all over the Surplus Lands (private development area ) and filling them back in. I wonder if that has anything to do with this? What are they looking for? Maybe the site remediation operation is actually a way for the Waterfront Development Office to fix this mess? Eliminate the rock sandwich?