Abstract: An improved flowable fill material and method for producing same that provides a medium for disposal of waste wood or other reclaimed debris, including wood treated with anti-microbial and/or anti-fungal materials including those containing copper, chromium and arsenic bearing compounds. The flowable fill material, comprised entirely of recovered and/or recycled materials, provides a medium for the safe disposal of chipped wood or other recovered waste by effectively encapsulating wood chips and substantially retarding further decomposition. Encapsulation of treated wood substantially reduces leaching of arsenic and/or other toxic substances contained therein. The systematic mixing of water, Class C fly ash, and wood chips in specific proportions carries out the present invention.