A massive, distended tube thirty feet in circumference and one hundred feet long lies on the bank of a drifting river, among the sludge and muck. A thick hose connected to a dredging barge is filling this black bag with the silt that it is sucking out of a nearby shipping channel. Once full, the tube will be tied shut and left in place. Fluids will slowly seep out, leaving dewatered sediments contained within the casing. This is the geo-tube.