Round 75% of Europe’s drinking water supplies come from groundwater. This shows a tremendous significance of this natural product regarding our future quality of life. The affinity to groundwater is in Stuttgart particularly high due to the local mineral water resources and springs, which are the second largest in Europe.
The groundwater quality in Stuttgart is considerable endangered by anthropogenic substances. Extensive pollution especially by volatile chlorinated hydrocarbons (CHCs) spreads over several aquifers (quarternary and Keuper layers) and reaches also the deep mineral water layer in upper Muschelkalk, where mineral water springs.
Especially in the urban and industrial areas, the CHCs are responsible for high spatial groundwater pollution due to their extensive usage as solvents in the past and poor biological degradation. The CHC-plumes can often spread up to several kilometers from the source. In order to predict groundwater quality trends and developments and to design remediation measures, contaminant plumes and large-scale pollution up to the scale of entire city districts must be identified and described.
The investigation of the CHC-contamination in Stuttgart began in autumn 1983, directly after the pollution of the mineral springs has been detected. In the meantime, the regional hydrogeological knowledge about the flow and dynamics of the whole system was compiled: the input of the contaminants in the mineral spring layer occurs predominantly due to the contamination in the urban area of Stuttgart and its boundary area.
In the project area 806 potential CHC-sources were known, from which 101 sources were investigated and evaluated before the project begun. At some sources the CHC concentrations of more than 1,000 µg/l could be detected. This corresponds to the exceeding of the trigger value for more than 100 times.
Despite an intensive site-specific investigation of the selected contaminated sources, which comprised mostly the shallow aquifers, as well as site-specific remediations, a considerable knowledge gaps existed at the beginning of the MAGPlan project. Regarding the deep groundwater aquifer upper Muschelkalk, which is the mineral water aquifer, the sources and transport paths of CHC were vast unexplained.
A stepwise processing of the remaining 705 possible contaminated sources cost at least 6 million Euros and was disproportional long-lasting. Therefore the integral groundwater strategy developed in the projects INCORE, MAGIC and FOKS was used, in order to identify the relevant CHC-sources, influencing the groundwater quality.