Q. Water control for sheet pile walls?
Ground water flow into excavations constructed by sheet pile walls must be minimized in order to save the cost of the provision of pumping systems or well points to lower water table inside the excavation. In case a layer of impermeable material such as clay is located slightly below the excavation, it can be desirable to drive the sheet piles further into this layer and cost of further driving can be less than cost of the provision of continuous pumping in the excavation.
Conversely if there is no impermeable layer underneath the excavation, engineers can consider driving the sheet piles further so as to increase flow path of groundwater into the excavation and this helps to decrease the amount of water flow into the excavation. In the same way a cost benefit analysis has to be carried out to compare the extra cost of driving further the sheet piles with the reduced pumping costs.