Microplastics and trichloroethene (TCE) are both common soil contaminants that are increasingly likely to co-occur. Because microplastics sorb chlorinated solvents, they may pull TCE away from the bacteria that would otherwise degrade it, but no physics-based model of this competition currently exists. We develop a one-dimensional advection-diffusion-reaction model in COMSOL that simulates TCE transport through a 1 m saturated soil column over 30 days, with simultaneous Monod-kinetics biodegradation and linear-driving-force sorption to microplastics. We sweep microplastic surface area, biodegradation rate, and water velocity and find that water velocity most influences contaminant fate by changing the rate at which soil saturation occurs, while biodegradation and sorption primarily influence contaminant fate before saturation is reached. The model provides a coupled framework for predicting TCE fate in microplastic-contaminated soil and a basis for prioritizing the parameters relevant to microplastic and TCE interaction in laboratory experiments or site cleanup.