Managed aquifer recharge and sedimentological characterization within the complex esker deposits in Paelkaene, Finland

摘要

It is proposed to construct a managed aquifer recharge (MAR) plant (capacity of 70,000 m_(3)/day) to provide potable water for over 300,000 inhabitants in Tampere and Valkeakoski region in Southern Finland. The plant includes the infiltration of surface water in a Quaternary glaciofluvial ridge (esker) with subsequent withdrawal of the water from downstream wells. We present the sedimentological characterization and rearranged MAR design of the 3 km long unconfined esker aquifer in Pälkäne (capacity of 20,000 m_(3)/day) that were needed to overcome the effect of discontinuities in the hydraulic connections along the Taustiala bedrock threshold as implied by a non-operational preliminary one-layer groundwater flow model. A more detailed sedimentological characterization was obtained by ground penetrating radar and a tracer test indicating flow paths and residence times of the infiltrated water. Four main hydrogeological units were distinguished. The bedrock threshold divides the groundwater flow into two preferred flow paths. The sedimentological interpretation was applied to determine the variation of hydraulic conductivities for the new seven-layer groundwater flow modeling. Sedimentological information together with hydrogeological studies was used in designing the sites and capacities for infiltration and withdrawal.