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Carrying out pumping tests in 2 phases of investigation.

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Pumping tests with several pumping stages are to be carried out at selected groundwater measuring points (GWM). The aim is to check the currently existing and known pollutant inventory at these GWMs and to verify possible deep shifts of STV. In addition, knowledge is to be gained with regard to the geometry of the pollutant plume. For this purpose, groundwater samples are to be taken at the beginning, during and at the end of the pumping tests in each pumping stage and chemically analysed for STV.

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The pumping tests are carried out at different times in two investigation phases. In the 1st phase, pumping tests will be carried out on 9 existing multiple GWMs, in the 2nd phase pumping tests will follow on selected multiple GWMs, which will be newly built in the course of the ongoing rehabilitation investigation. A total of 31 pumping tests are expected to be carried out in the 1st phase and an estimated 20 pumping tests in the 2nd phase. In all areas, groundwater is always to be expected that is contaminated by STV, but also by other pollutants typical of contaminated sites.

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In the 1st investigation phase, pumping tests are planned to verify the vertical displacement of STV on selected GWMs. The aim is to check whether there are false findings at individual deep measuring points or whether the depth displacement actually existed or exists. In addition, pumping tests are carried out at individual measuring points to check the plume geometry.

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In the 2nd phase of the investigation, the pumping tests are used not only to investigate the spread of pollutants but also to check the performance of the groundwater measuring points that are still to be built in the course of the remediation investigation. These are not planned as measuring point bundles, but as individual measuring points in their own borehole (measuring point group).

The procedure and sequence of the pumping tests of the 2nd phase is analogous to the pumping tests of the 1st phase. However, since the expansion of the new GWM is carried out uniformly with DN 125, larger pumps are to be used in the 2nd phase and correspondingly higher flow rates are to be set in the individual pumping stages (up to 5 to 10 m³/h).

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