Experimental recharge by small-diameter wells: the Pirna, Saxony, case study

Managed aquifer recharge has been used for various regions worldwide to improve water quantity and quality. Furthermore, contaminated site treatment often requires injection of water together with specific additives to support natural attenuation processes. Händel et al. (in J Hydrol 517:54–63, 2014. doi:10.​1016/​j.​jhydrol.​2014.​05.​003) introduced a new recharge approach, applying cost-efficient small-diameter wells. Numerical studies were applied, among others, to investigate the effect of subsurface structures on injection process. Besides this, a comparison with an infiltration basin was made. To close the gap between the theoretical work and the practical use of this technique for medium-term injection of clean waters and to provide an experimental validation of the small-diameter well recharge, two injection tests using a small-diameter well (1″ inner diameter) were performed at the test site Pirna, Saxony, Germany. In a first short-term test, stepwise increasing injection rates were applied and showed only a slight increase in well water levels. In a second test (using the same well), groundwater was injected continuously for 14 days. The constant injection rate of 0.75 l/s resulted in a recharged water volume of 900 m³, showing the high-performance potential of such wells for clean water infiltration.