Modeling Natural Attenuation of Total BTEX and Benzene Plumes with Different Kinetics

Natural attenuation has emerged as a potential alternative for remediation of sites contaminated with fuel hydrocarbons. This paper compares the results from modeling the natural attenuation of BTEX (benzene, toluene, ethylbenzene, and xylene) at a coastal site to the results from a benzene model at the same site. Field data for total BTEX and benzene were used to develop model parameters for the Bioplume III site model. A first-order kinetics expression was used for benzene and an instantaneous expression for BTEX. Modeling results showed shorter cleanup timeframes for benzene than for BTEX. Natural attenuation cleanup times using BTEX and assimilative capacity are 47% to 90% higher than those for benzene alone. Cleanup times for benzene of ~100 years were estimated from model predictions, whereas predicted cleanup times for BTEX varied between 150 and 200 years.