Reconstruction of Open Basins for Artificial Groundwater Recharge into Covered in Filtration Trends (Neckartailfingen, Germany)

Abstract

The waterworks in Neckartailfingen (Baden-Württemberg) intend to improve the artificial groundwater recharge facilities. Drinking water is produced by infiltrating treated water of the Neckar River into open basins embedded into a shallow gravel aquifer. To extend the operation time of the open basins and to reduce the treatment procedures for the filter sand, the possibilities to restructure the infiltration and recharge systems were investigated. The investigations in the period from 2012 to 2014 confirm that the artificial groundwater recharge with covered infiltration trenches (SSG) works in quantitative and qualitative terms without limitations. The water quality of infiltration water governs the specific yield and lifetime of the covered trenches. The concentrations of Fe, Mn, Ca and HCO3 as far as turbidity are of great importance for the operation of the infiltration system. So far, after 2 years of operation, only minor carbonaceous deposits in the upper layer of filter sand near the point of discharge were observed in the SSG. These deposits derive from the treated Neckar water. For further operation the design of SSG should reduce turbulences and should ensure feeding of the trench along the entire length. The further development of the water quality on the underground flow path to the extraction wells is determined by the hydrogeological properties and the hydraulic conductivity of the quaternary aquifer. There was no proving of changes in the water quality influenced by the higher specific infiltration rates in the SSG compared with the open basins.