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SIMULATION OF INTRINSIC BIOREMEDIATION PROCESSES AT WURTSMITH AIR FORCE BASE, MICHIGAN
Citation:
Chen, Y. M., L. M. Abriola, AND M. J. Barcelona. SIMULATION OF INTRINSIC BIOREMEDIATION PROCESSES AT WURTSMITH AIR FORCE BASE, MICHIGAN. Fourth International In Situ and On-Site Bioremediation Symposium, New Orleans, LA, 4/28-5/1/97.
Description:
In October, 1988, a KC-135 aircraft crashed at Wurtsmith Air Force base (AFB), Oscoda, Michigan during an attempted landing. Approximately 3000 gallons of jet fuel (JP-4) were spilled onto the ground, with a large portion of the fuel entering the subsurface. Previous investigations, through coring and well water data analysis, revealed that a dissolved BTEX plume exists and is attenuated in part due to intrinsic bioremediation. To assist in the understanding of the plume evolution and ongoing biotransformation processes at the site, a two-dimensional site-specific cross-sectional reactive-transport model is under development. The basis for this model is the MUST (Michigan Unsaturated/Saturated Transformation) Model. MUST is a finite element simulator designed to simulate in-situ bioremediation of volatile contaminants in variably saturated aquifers. Modeled processes include advective and dispersive transport, mass transfer between constituent phases (water, soil, gas, NAPL, and organisms), and Monod-type microbial transformations and growth under various redox conditions. In this paper, a preliminary investigation is presented which focuses on model calibration to reproduce the observed natural attenuation of the plume at the site. Major calibrated parameters include vertical transverse dispersivity, the location and composition of residual NAPL distribution, and the initial microbial distribution. The value of the calibrated apparent biodegradation rate in the aerobic plume is 0.018 day-1, which is within the range reported for other BTEX contaminated sites. On-going work is focused on the exploration of the influence of vadose zone processes and water table fluctuations on the attenuation rate at the site.