The research, conducted in partnership with Oasen and Visser & Smit Hanab, aims to establish whether water can be abstracted more efficiently using HDDWs at the Rodenhuis wellfield in the Province of South Holland. Because the area surrounding the current well row is limited, the research also studies how the wellfield can be best designed on land recently acquired by Oasen. A key precondition is that no significant lowering of the water table can occur outside the boundaries of Oasen’s property.
The analyses shows that replacing the current linear configuration with vertical wells is the most advantageous from a cost perspective. A more dispersed configuration with vertical wells on the recently acquired parcels is more costly because of the need to bridge ditches and install extra pipework. For this latter configuration, HDDWs offer a cost-competitive alternative. Hydrological model calculations however indicate that a small shift in the gravity point of the abstraction leads to a change in the level of the water table outside the boundaries of Oasen’s property. This means there is little room for alternative production techniques and well configurations. Moreover, it also means that the screens of the HDDWs would be located very close to each other. During the well installation and maintenance operations, neighbouring wells would have to be shut down in order to guarantee good water quality. Under an HDDW configuration, this implies that during maintenance operations two of the five wells would be shut down and the remaining wells would operate at maximum capacity to guarantee supply security. In conclusion, one can state that for the Rodenhuis wellfield, within the available license area, the possibilities are insufficient for the implementation of alternative production techniques and well configurations.