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Fate and Transport of a TCE Groundwater Contamination Plume
The world’s largest plume of trichloroethylene (TCE) contamination is located in Mancelona, Michigan. It extends about 6 miles and has polluted drinking water wells in that northern community. The contaminated aquifer is estimated at 13 trillion gallons. Currently, Mancelona residents have a municipal water system that provides them with safe drinking water. The TCE plume is venting into the Cedar River which flows into Lake Bellaire, which ultimately discharges into Lake Michigan. TCE has been detected in groundwater in some locations as deep as 500 feet below the ground. The exact depth of TCE in groundwater at any given location depends on the local ground topography. The maximum contaminant level of TCE in drinking water is 5 parts per billion (ppb), and TCE concentrations in groundwater below 200 ppb can safely flow into or vent to surface water, such as rivers, lakes or wetlands. However, TCE levels as high as 500 ppb were detected. There are 121 permanent monitoring wells have been installed to determine groundwater flow direction and rate. These wells monitor TCE concentrations in groundwater and the change in TCE levels over time. The aim of this study is to model the extent of the TCE plume to help assess the environmental impact on the aquifer. BIOCHLOR v2000 from EPA is used to model the fate and transport of the contaminant. The model simulates a three-dimensional advection transport based on the past movement of plume. The results show that the model follows closely the sampling data previously collected. Modeling the plume is of vital importance as it predicts the time it takes for TCE to reach Lake Michigan and contaminates the drinking wells along its path.