With the aim of optimising the dewatering line of the soil washing plant Ground Unit, experimental studies were carried out in cooperation with the Chair of Mineral Processing at Montanuniversitaet Leoben. The extent of work of this master thesis was divided into three key activities: 1) Flocculation trials on different suspended soils that should indicate the efficiency of flocculants used in dewatering processes and enable plant operators to choose the most adequate flocculant in the future. 2) Soil analyses performed on-site at Ground Unit by means of regular sampling and evaluating parameters that are contributing to the dewatering performance. 3) Comparison between different soils in order to prepare recommendations and a work procedure how to analyse and process so far unknown soils to guard against standstills of the dewatering line. An additional focus appeared while the experimental work in the plant was carried out. Issues concerning processing equipment and the soil washing process were detected and were either improved throughout this thesis or described as future enhancement potentials. Moreover, slight financial savings achieved by flocculant improvements and consequential demand decrease were determined.