What happens when an underground gas tank leaks?
This is a relatively common environmental problem. The first thing that happens is that the oil (or gas as in gasoline but not gas as in natural gas) tends to fill up the soil in the original excavation made for putting the tank in the ground. Usually sand is used as fill around the tank and this is a porous material that has a lot of space for liquid to fill. over time, the oil (gasoline) will also migrate into the surrounding sediments. Normally the oil will migrate primarily downward until it hits the water table. When it hits water, it then starts to spread sidewards (oil floats on water). This sidewards movement may occur right away if the water table is high and already at the level of the tank (quite common). As the oil moves, it coats the particles of soil and contaminates the stuff. Once it hits water, it also contaminates the water, and the water is always moving, even if slowly, and thus the contamination will migrate in the same direction as the groundwater is moving. If th
