SUBSURFACE GEOLOGY OF THE AMERICAN BOTTOMS IN THE MISSISSIPPI RIVER FLOODPLAIN

In the American Bottoms of the Mississippi River floodplain, north of East St. Louis, there are towns, farms, and numerous industrial complexes including several petroleum refineries. Over the past century, industrial spills on the land surface and from buried pipelines have resulted in the formation of subsurface hydrocarbon pool(s). One or more of these pools resides under the town of Hartford, Illinois. Complaints of obnoxious odors by residents in the community have been ascribed by some to vapors migrating up from the hydrocarbon pool(s).

Lithologic data from bore holes have been obtained from numerous public and private sources to better determine the lithologic / stratigraphic units in the American Bottoms with special emphasis on the region around the refineries near Hartford and Roxana, Illinois. To date, lithologic data from approximately 900 boreholes are being used to develop a 3D model of the subsurface geology. This model will provide the geologic framework in which the hydrogeology and hydrocarbon movement can be investigated numerically. Results of this work will provide additional insights into the movement of the hydrocarbons in the Hartford and Roxana areas and the potential source(s) of gas vapors responsible for the Hartford residents’ complaints.