In my area, the general understanding is it must be "dry" as MEP stated. I fill my empty chemical containers with the mud. It might seem like overkill but I remove all the labels from the barrels just in case. I use the 5 gal ones for daily mud clean up in the bays and the few 30 gal ones for pit mud. I cut the tops off the 30 gal ones with a circular saw. I then haul it over to my shop and let them sit out back for a few weeks. I then toss them in the dumpster. I started buying certain chemicals in 30 gal drums for this reason. I also have a lift gate on my truck which I bought for this reason as well. I admit I have the tools in order to do this, but most of us know the costs involved with professional removal so I think I have paid for the lift gate and likely part of my warehouse. I even, from time to time, hire contract labor from those labor places to shovel the mud. One final thing, has any else used this stuff in their landscaping? I started using the mud I cleaned up off the floor in the bays, so I could see that there was no trash in it, in my flowerbeds. WOW!!! I knew some people in college that would have paid good money for this stuff.