Alteration of groundwater table: Impacts on foundation

We everyone know the term buoyant effect of water. This phenomenon is important in ground condition alteration. It is evident that intergranular pressure is increased with the removing of buoyant effect of water. This can be achieved by lowering the water table. In many practical cases this is not feasible or sometimes it is used as temporary solution. If somehow ground water table are altered, the immediate increase in intergranular pressure is obtained by 

γ_w x z_w

Where z_w is the change in ground water elevation.

Now think that water table alteration is possible, feasible and effective. Then another problem arises with alteration limit avoiding adjacent property. The water table cannot be altered exactly within the limits of desired property. Thus the change in effective pressure also occurs beneath adjacent properties of which foundation are designed considering existing ground water condition. The resulting impacts are cracked pavement or floor as well as cracked building.

It is worth mentioning that ground water table can be raised producing the same problem of adverse impact on adjacent properties and requires careful understanding about the impact before achieving the raising.

Thus any alteration of ground water table results some kind and degree of effect on the environment. So it is necessary to take permission from the local environmental authorities to adopt such action.