It might contain arsenic, it depends on the type of treatment (copper chrome arsenate or CCA is the older style, now there are others like ACQ which don't contain arsenic.)
Since the treated wood is sent to landfill I assume that's where the ashes need to go too. I don't think it requires any special kind of waste management (despite what we know about dumps leaching nasty stuff out years after they are filled and abandoned.)
Burning CCA wood releases the chemical bond holding Arsenic in the wood, and just one Tablespoon of ash from a CCA wood fire contains a lethal dose of Arsenic.
Even more astonishing, minute amounts of 'fly ash' from burning CCA pressure treated wood, can have serious health consequences. The Journal of the American Medical Association reported on a family that burned CCA in a wood stove for winter heating. Their hair fell out, all family members suffered severe, recurring nosebleeds, extreme fatigue and debilitating headaches. The parents complained about 'blacking out' for periods of several hours, followed by long periods of extreme disorientation. Both children suffered frequent seizures described as 'grand mal'. The symptoms were finally traced to breathing minute amounts of arsenic laden dust leaking from the furnace as fly ash. The family's houseplants and fish died, too, victims of copper poisoning from the same dust. Peters HA, et al: Seasonal exposure to arsenic from burning CCA wood. JAMA 251:(18)2393-96, 1984)
So, please be careful handling that dust!
Location: Adelaide, South Australia (Mediterranean climate)
There should be more information available to the customer when making the purchase --something like "hey dummy, don't burn, eat or smoke this" For cleanup: I wet the ashes down so they would not be flying about, then once the water was drained off, put the remains in a thrash bag and sent it to the dump. But, it makes we wonder how many Americans have this stuff sitting in their yards having no idea of its toxicity.
Thank you my well lotioned goddess! Here, have my favorite tiny ad!
Solar Station Construction Plans - now FREE for a while