Modeling natural attenuation of fuels with BIOPLUME III

A natural attenuation model that simulates the aerobic and anaerobic biodeg radation 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 biodeg radation limited further plume expansion and accounted for approximately 30 % of the overall contaminant reduction. Anaerobic biodegradation, in compar ison, accounted for more than 65% of the mass loss and concentration declin es and caused a shrinking of plume dimensions through time. Application of the model to Site ST-29 at Patrick Air Force Base demonstrated the viabilit y of natural attenuation as a remedy for the existing fuel hydrocarbon plum e at the site. Model simulations indicated that a stable plume will be esta blished within 30-40 years and that the plume extent will likely stabilize to <170 m (500 ft) downgradient from the source area.