Thank you. Yes, it is almost a bucket of (new) left over paint and primer. Looks like he cleaned the buckets and paint brushes there.

Definitely call and complain. If he's a lone operator he needs to know that this is an unacceptable practice. If not, the company he works for needs to know what he is doing. It's probably not just a fluke, but something he's done before. If you don't let them know they can't correct the situation. As small business owners we'd much rather a customer call to complain so we can rectify the problem going forward.

You should look into the MSDS for the particular varieties of paints that were disposed of -- latex? enamel? alkyds? They all do pretty nasty outgassing when wet (e.g volatile organics such as ethylene glycol, formaldehye, etc.), but once they are dry, I believe they are pretty benign. Especially for interior paints, it would be dumb to have bio-unfriendly walls once they are dry. We are not warned to wash our hands after touching our walls. Very true that lead-based paint would have lasting bad effects, but those paints are long since banned. Not well known, but until 1990, mercury was added to paint as a mildew inhibitor. That would not be good to have in your garden. So I'd hope this wasn't old paint being used.

I think the bottom line is that, no, replacement of soil probably isn't necessary.

Did you hire the Moe, Larry, & Curly Acme Painters Inc? Definitely numb skulls!

Now for the point of view of a painter. This is NOT a rare occurrence as all painters have to clean up somewhere somehow.

Firstly, there is nearly NO non-latex paint used any more. Secondly, there is nothing toxic in any non-industrial paint any more. Thirdly, nobody dumps buckets of perfectly good new paint.

Fourthly, what accommodations did you make so the painter could clean up after painting? If none, then the painter had to pick a spot. If the painter can't clean up, they you would have to pay for those ruined thirty dollar brushes and pans and rollers and so on. Clean-up takes water running through the thick paint residues until the tools are clean enough to be used again on the next job. You can't let that paint-y water run down the sidewalk or gutter or people would complain about THAT! Paint is designed to cover, so it looks like there's a lot when it's really just very very thin latex resins and pigments in lots of water.

So, what accommodations did you make so the painter could clean up after painting?

Well I can certainly buy oil based paint, which is very much a non-latex. But again, any toxicity evaporates away as the paint dries.

That being said, let's remember that the painter is getting paid to do a good job. If the painter needed a cleanup site, the painter really should have asked for one. That strikes me as a responsibility of the job that they're getting paid to do competently. Now, I can't assume that all painters would recognize a garden bed if they tripped over it. "Looks like dirt to me!" So it's not necessarily a matter of stupidity that they dumped it there. It is a matter of carelessness for not asking.