Hydrogeological and geotechnical aspects of the Tennessee-Tombigbee Waterway

The Tennessee-Tombigbee Waterway is in the East Gulf Coastal Plain physiographic province The River and Canal sections were constructed on the floodplain of the Tombigbee River Locks and dams in this section are founded on sediments of Upper Cretaceous age, composed predominantly of sands, clays, and silts of the Eutaw and Gordo formations The 39-mile long Divide Cut was excavated through higher topography which is underlain by these same formations, along with the McShan formation of similar character Bay Springs Lock and Dam, at the south end of the Divide Cut, is founded on shale of the Hartselle formation, which is Mississippian in age Comprehensive studies and tests were made to evaluate and monitor potential impacts of the waterway on the hydrogeologic environment Observations to date show that adverse impacts are very minimal overall, and these are partially offset by beneficial effects Geologic and groundwater conditions were primary factors in the location and design of major features of the waterway During construction, extensive control of groundwater and dewatering effort was required The excavation, utilization, and disposal of over 200 million cubic yards of material, construction of 10 locks and dams, and over 80 miles of canal were accomplished essentially as planned and designed within budget and ahead of schedule