L.G.
how to keep the 22 month old from dumping... had the same problem. Hold onto the bin you are putting things into so he cannot dump it.
Are the bins able to be put up (after cleaning up) somehow so they are not accessable? Making it a "yes" environment as much as possible was really the only thing that worked for me. I only had as many toys out as I was willing to step over or clean up.
And too- as soon as he heads back over to the bins to dump them, stop him and redirect him to whever the new activity is... just keep redirecting. At this age- well any- they want to know how firm the boundary is- so they keep testing.