This thesis describes the creation of RECOVERY-RD, a numerical model capable of representing the biotransformation processes associated with Polychlorinated Biphenyl (PCB) compounds in contaminated sediments for a variety of aquatic environments, including rivers and marine systems. RECOVERY-RD is intended as a screening tool for evaluating the impact of engineered sediment caps on contaminant remediation. The two key components that provided the framework for RECOVERY-RD are RECOVERY, a model for contaminant transport in stratified sediment, and SEAM3D, a numerical transport model for contaminated groundwater systems. The predictions made by RECOVERY-RD are verified using a series of test cases organized to test each phase of the modification process individually. The results show that the processes simulated by RECOVERY-RD are reasonably represented when compared to alternative calculation methods that have been previously verified. A hypothetical application of the initial version of the model provides evidence of the usefulness as a screening-level tool for the assessment of remedial efficacy. / Master of Science