I was reading the posts to the thread " Hey brother-in-law, can I borrow the rig for a couple of weeks next month?"
and near the end Hazmat Cleanup was mentioned as one of the perils that could befall an uneducated operator.
The only thing comes to my mind would be black, and possibly gray water on the ground. Never thought of it being a hazmat issue but I guess if it were released 'on the ground', especially around the pad it would be a mess to clean up, but I wouldn't think of hazmat. Might also depend on your location.
When I think hazmat I think of diesel fuel, oils, etc. Should I include water as well? What say you?