This is the best way I have found to renovate my heavily quack grass infested bed, but it will take a lot of time. I have a wheelbarrow that I put the dug clumps in and let them soak until I get a chance to pull them apart and remove the quack grass. It can spear itself right through the roots and rhizomes. Every now and then I dump the water and add fresh, not necessary every day.
Actually, I am moving the DL's to another bed that doesn't have this problem. Eventually when they are all moved then I can dig this bed and get all the quack grass out.

I've done this before and need to do it to a couple of plants this year, if I could just find the time! And the energy!

That's the thing about this method - all you do is dig and plop in the water until you feel like doing more!

I do that when I'm trying to separate clumps into fans... Leave em in water for a few days, swirl them around a couple of times to dislodge more dirt and eventually, I get fans apart while wearing a little less mud...

Yes, much easier!