How should I dispose of treated wood or manufactured boards?
When it burns, treated wood emits all sort of nasty chemicals that it was treated, such as trivalent chromium, copper sulfate, and arsenic. Not good stuff to breathe or pump into the air. If you can't find a way to use the leftover wood, the most responsible thing is to just take it to the dump. At least they'll have waste and runoff containment systems.