Geoelectrical mapping for improved performance of SUDS in clay tills

Many cities of the Northern Hemisphere are covered by low permeable clay tills, posing a challenge for stormwater infiltration practices. However, clay tills range amongst the most heterogeneous types of sediments and infiltration rates can vary by several orders of magnitude. This study evaluates if a 2D geoelectrical system can reveal such heterogeneity at field scale and thus be used to optimize the hydraulic performance of stormwater runoff infiltration systems. The assessment is based on a field study where data from non-invasive geoelectrical data are compared with data from invasive geological methods, including borehole soil sample descriptions, one excavation description and a near-surface spear auger-mapping project. The experiments returned a significant correlation of geoelectrical and spear auger-mapped surface sediments. Furthermore, a highly permeable oxidized fracture zone in greater depths could be revealed on the 2D geoelectrical profiles. The successful determination of highly permeable zones harbors potential for improved hydraulic performance of infiltration SUDS (sustainable urban drainage systems).