This pilot EGS project is located within the Upper Rhine Graben. Five deep boreholes (3.6 to 5 km deep) have been drilled in fractured crystalline rocks. Several hydraulic and chemical stimulations have been carried out for improving the initial injectivities or productivities of the 5 km deep reservoir. Long term hydraulic tests have been done and proved the hydraulic performances of the deep-seated fractured granite. An Organic Rankine Cycle (ORC) binary plant has been built in 2008 but due to severe corrosion issues related to the salinity of the natural brine a full renovation of the surface geothermal installations was required (Scheiber at al., 2015). A new geothermal power plant was installed and was commissioned in August 2016. In the framework of the DESTRESS project, it is planned to evaluate the impact of soft treatments on injectivity index during long term exploitation. Thus, specific chemical treatments for injectivity improvement, downhole logging as well as relevant monitoring can be performed at this geothermal site for longterm circulation.