You could reburn and reburn the debris. If you keep consolidating the piles you can burn it pretty much to nothing. I also found having a backpack blower sitting there blowing on the fire can get tremendous heat and reduce even wet stumps to nothing.

Or burn the best you can, then push the piles into one pile and push the debris in the bottom of the pond in a shallow area where you could get to it if it starts separating or moving around. If you lash the debris into a somewhat compact pile it will water log and sink and become a fish attraction without compromising the bottom of the pond