Someway I missed your post. A bit late but if still looking, this is the way I do it on all wood as it is so cheap,easy, and practical for large stuff.
I do a bleach soak and it has been totally safe for a very long time. Like fifty years safe?
I add the wood to whatever container will hold it. At times that has been the tank itself as that was the largest I had that would fit. Then using cheap, no color, no scent bleach, I add an amount that looks right for how dirty the wood seems. Chlorine in bleach reacts with organics of all sorts, so if there is a lot of gunk that I've not rinsed off, I use more bleach and just make sure I have plenty to get the job done. It may eat some of the wood but I don't worry about it eating a tree trunk! A half cup in 50 gallons for a big old piece but I really don't measure.
I let it set at least 8-10 hours or more until I get back to the job. Then I take it out, rinse it to make it easier to hold and set it out to dry. Sn and heat are nice as they speed the process but when I no longer smell bleach, I have to say the chlorine has gassed off and it is safe to use. Chlorine can't soak into the wood and stay there to come out later. It either reacts with the wood or gasses off, it can't hide out.
Watch the clothes, wear old ones and try to avoid splashing. It does eat your shirt if it gets a chance!