That 80/20 silt rule I always ignored... turns out it matters

I was chatting with a older operator down at the Evansville yard last Tuesday. He told me if your dredge output is more than 20 percent silt, you're basically just churning water and wearing out your pump for nothing. Looked it up that night in the old Army Corps manual I found online and sure enough, the efficiency curve drops hard past that point. Has anyone else been running blind on this and just guessing based on feel?

3 comments

3 Comments

xena115d ago

Oh man, yeah that silt rule caught me off guard too. I used to just eyeball the discharge and guess based on how thick the stuff looked coming out. Then I got stuck on a job where we were pumping what I thought was fine material but the GPH just kept dropping. Finally broke down and had a sample tested. Turned out we were at about 28 percent silt. Switched to a different cut pattern that kept us out of the silty pockets and our production jumped back up by almost a third. I still don't obsess over exact percentages but I do keep a simple jar test handy now. Fill a mason jar with some output water, let it settle for a few minutes, and you can eyeball if the silt layer is way too thick. That old school trick has saved me more headaches than any manual ever did.

oliviagrant15d agoMost Upvoted

It's wild how one little thing like that can mess up a whole operation without you even realizing it.

kelly_west7415d ago

Read something in a trade mag that said the same thing about silt killing your GPH.