Measuring groundwater level and pressure
Groundwater level and pressure are measured in order to assess the groundwater conditions in the vicinity of the federal waterways. These measurements form the basis for predicting changes to groundwater conditions caused by construction measures within the framework of hydrogeological expert reports, for determining groundwater pressure and flow actions on concrete and earthwork structures or excavation pits, for collecting groundwater evidence and for monitoring the groundwater around structures.
Groundwater level and pressure measurements can be taken in open or closed groundwater observation wells. Open groundwater observation wells are used for soils or rock with medium to high hydraulic conductivity. They consist of a filter and a standpipe that extends to the ground surface and that enables atmospheric pressure to be compensated for. In open groundwater observation wells, the water level in the standpipe is measured either manually using a light plummet or automatically by means of a pressure transducer in the standpipe, with the measurements being stored on a data logger. However, they are only of limited use when it comes to measuring rapid changes of pore water pressure in less permeable soils or rock, in which case closed groundwater observation wells are used. These consist of a pressure transducer surrounded by a sealed filter zone, which is fitted directly into the ground. The measured data are recorded by a data logger installed on the ground surface.
BAW creates detailed project-specific guidelines for the selection and development of the groundwater measuring system together with appropriate procedures in accordance with local conditions and the necessary data. It monitors the preparation of the measuring wells and the installation of the measuring technology and analyses the measurements. Specific measurement systems are developed for particular requirements (e.g. measuring groundwater pressure under weirs and lock beds).