Came across a stat about riverbed sediment compaction that changed my spoil line plan

I was reading a report from the Army Corps of Engineers on the Missouri River near Omaha, and it mentioned that in some sections, the top layer of sediment can compact by almost 40% once the water pressure from the dredge head is removed. I always figured there was some settling, but that number hit me. We were about to start a job estimating spoil volumes based on loose material, and that kind of compaction would have left us short on disposal capacity. It made me go back and check our calculations with our project manager. We ended up adding an extra 15% buffer to our volume estimates for the siltier sections, which saved a huge headache later. The report was from 2019, but the geology hasn't changed. Has anyone else had to adjust their plans for major compaction like that, or is the Missouri just extra squishy?

3 comments

3 Comments

spencer_park261mo ago

Wait, 40% compaction? That's insane, I would have never guessed it was that high. Makes you wonder how many projects got messed up by not knowing that.

diana5121mo ago

Yeah, it's a huge number that catches people off guard. Seen a few slabs poured too thin because the crew just went with the truck volume. Always tell people to get a proctor test first, even if it feels like extra work. That 40% is basically free material you're paying for if you don't account for it. Saves a ton of headache and cost down the line.

vera_robinson361mo ago

Ever notice how most things shrink when you pack them down tight? It's just not dirt.