Horizontal directional drilled wells (HDDW) enable a better depth control on groundwater abstraction and infiltration. Within Subsol, we develop a cost-effective and robust HDDW for SWS implementation. Last week, a new, low-cost version of the HDDW was installed in Groede. Here, a 70 m long HDDW was installed at 10 m depth in order to abstract freshwater from a groundwater lens for summer irrigation in a fruit orchard. For the first time, a PVC wire-wrapped well screen (75 mm CSS Boode) was used. A 125 mm perforated HDPE pipe provided the protection of the well screen when it was pulled in. The more advanced PVC screen replaces the more vulnerable well screen used at the Ovezande reference site (HDPE wrapped in geo-textile) and is expected to result in higher yields and less clogging.
Upon installation, the well was cleaned by HD jetting and is the well now being developed by pumping in order to remove bentonite and fine sand around the well. Up to now, the results (groundwater quality and well capacity) look promising. With this new procedure, new opportunities are created to sustainably replenish and exploit shallow groundwater lenses with SWS in the Zeeland area, were recent SkyTEM measurements showed a vast presence of shallow groundwater lenses (between 5 to 30 m thick) and current abstraction methods (shallow drains and vertical wells) prove vulnerable to because of capacities and salinisation.