Stacked GCW
The achievable sphere of influence of a GCW-System depends on the distance of the two active screen sections, the anisotropy of the aquifer, the groundwater flow velocity and the selected pumping rate. The bigger the circulation cell is, the longer a water molecule needs to pass through the cell. With huge aquifers it turns out to be advantageous to arrange several circulation cells (multiple circuits, "stacked circulation") on top of each other. Thus, smaller circulation cells with shorter flow periods are formed. The application of such multiple-screened GCWs can also be advantageous if the contamination is restricted to certain aquifer sections or if the hydro-chemical characteristics of the groundwater change with the depth of the aquifer, thus requiring dedicated units vertically and horizontally.