Modular Computer Code for Simulating Reactive Multi-Species Transport in 3-211 Dimensional Groundwater Systems

摘要

RT3DV1 (Reactive Transport in 3-Dimensions) is computer code that solves the211u001ecoupled partial differential equations that describe reactive-flow and transport 211u001eof multiple mobile and/or immobile species in three-dimensional saturated 211u001egroundwater systems. RT3D is a generalized multi-species version of the US 211u001eEnvironmental Protection Agency (EPA) transport code, MT3D (Zheng, 1990). The 211u001ecurrent version of RT3D uses the advection and dispersion solvers from the DOD-211u001e1.5 (1997) version of MT3D. As with MT3D, RT3D also requires the groundwater flow 211u001ecode MODFLOW for computing spatial and temporal variations in groundwater head 211u001edistribution. The RT3D code was originally developed to support the contaminant 211u001etransport modeling efforts at natural attenuation demonstration sites. As a 211u001eresearch tool, RT3D has also been used to model several laboratory and pilot-211u001escale active bioremediation experiments. The performance of RT3D has been 211u001evalidated by comparing the code results against various numerical and analytical 211u001esolutions. The code is currently being used to model field-scale natural 211u001eattenuation at multiple sites. The RT3D code is unique in that it includes an 211u001eimplicit reaction solver that makes the code sufficiently flexible for simulating 211u001evarious types of chemical and microbial reaction kinetics. RT3D V1.0 supports 211u001eseven pre-programmed reaction modules that can be used to simulate different 211u001etypes of reactive contaminants including benzene-toluene-xylene mixtures (BTEX), 211u001eand chlorinated solvents such as tetrachloroethene (PCE) and trichloroethene 211u001e(TCE). In addition, RT3D has a user-defined reaction option that can be used to 211u001esimulate any other types of user-specified reactive transport systems. This 211u001ereport describes the mathematical details of the RT3D computer code and its 211u001einput/output data structure. It is assumed that the user is familiar with the 211u001ebasics of groundwater flow and contaminant transport mechanics. In addition, RT3D 211u001eusers are expected to have some experience in using the MODFLOW and MT3D computer 211u001ecodes and must be familiar with their input/output data structure.