BHM Geotechnical provides specialist advice for acid sulfate soil assessments from qualified Environmental Engineers to clients. Acid sulfate soils are naturally occurring soils containing iron sulfide minerals, principally pyrite. Acid sulfate soils form in waterlogged anaerobic conditions, where sulfate-reducing bacteria convert dissolved sulfate into Reduced Inorganic Sulfur (RIS). Significant environmental hazards have occurred from acid sulfate soil (ASS) disturbance when exposed to oxygen, which may include, severe acidification of soil, deoxygenation of water bodies, and scalding. This guide is intended to assist in identifying the presence of acid sulfate soil and its associated hazards.