Modeling Natural Attenuation of Fuels with Bioplume III

A natural attenuation model that simulates the aerobic and anaerobic biodegradation of fuel hydrocarbons was developed. The resulting model, BIOPLUME III, demonstrates the importance of biodegradation in reducing contaminant concentrations in ground water. In hypothetical simulations, aerobic biodegradation limited further plume expansion and accounted for approximately 30% of the overall contaminant reduction. Anaerobic biodegradation, in comparison, accounted for more than 65% of the mass loss and concentration declines and caused a shrinking of plume dimensions through time. Application of the model to Site ST-29 at Patrick Air Force Base demonstrated the viability of natural attenuation as a remedy for the existing fuel hydrocarbon plume at the site. Model simulations indicated that a stable plume will be established within 30-40 years and that the plume extent will likely stabilize to <170 m (500 ft) downgradient from the source area.