Modeling natural attenuation and enhanced natural attenuation of chlorinated benzenes in groundwater

This study examines a plant in southeast Texas, where the aquifer is contaminated with dichlorobenzene (DCB) and chlorobenzene (CB). The goal is that one-dimensional and two-dimensional predictions of the transport of contaminants in groundwater were performed in this project. A regression of concentration versus distance for stable plumes is coupled to an analytical solution for one-dimensional, steady state, contaminant transport. The regression yield a biodecay rate constant based on field data. A software package called MoNA (Monitored Natural Attenuation) is used for these calculations. Since some errors were found in this software for calculating decay rate constant, modification is necessary for this study. The modified results are used to examine the existence of natural attenuation and its extent, in the form of predictions of the volume of the contaminants consumed at the plant site. Sensitivity analysis is performed to estimate the effect on the total decay rate constants, of concentration contour line locations, groundwater velocity, bulk density and fraction of organic carbon. For two-dimensional prediction, BIOPLUME III, which is a two-dimensional, finite difference model for simulating the natural attenuation of organic contaminants in groundwater due to the processes of advection, dispersion, sorption, and biodegradation, was used to answer how long the contaminant plumes would persist or extend if oxygen injection treatment is implemented.