Abstract: Synthetic soil is created by blending processed or unprocessed incinerator ash, derived from solid waste or other materials, with either compostable materials or compostable materials derived therefrom. The blending of these materials results in residual biotech soil which can be used as a plant-growth medium; as cover material for such things as landfills, disturbed soil areas or mined-land reclamation; and as a medium to treat contaminated water.