The dam at Kleine Roth is a significant part of the "Water Channel System from the Altmühl and the Danube to the Regnitz-Main Region". The dam is advantageously located in direct proximity to the Main-Danube canal, its main function is the temporary storage of rising water, which is largely pumped inexpensively at night time and weekends.
To achieve the required operating space of 7 million cu.m (9 million cu.yds.), a storage dam with a maximum height of 20 m (66 ft.) over the foundation base with a dam crest length of 1.7 km (1 st.mile) is necessary. The sealing core connects to the subterranean sealing in the contact surface of the dam. A 60 cm (23 1/2 in) thick cut-off wall of earth and concrete closes off the entire area of the erosion trough and the highly permeable and fissured sandstone surrounding it. This was produced by means of a Bauer trench cutter at depths of 30 m (98 ft.) or more.
To ensure the dam against underflow, it is extremely important that the individual panels of the cut-off wall connect perfectly to each other down to the lower depth. The owner has therefore justifiably set strict tolerance limits for the verticality and requested unquestionable proof thereof.
The verticality is being constantly monitored electronically by us during the excavation process, so that in the event of deviations in either the vertical or horizontal axis of the wall, corrections can be made. After completion of the shaft, ultrasonic test measurements are again made on both axes and directly recorded on a plotter. From this it is apparent that the deviation from vertically is in the magnitude of only 0.1 %, far below the required tolerance of 0.2 % of the shaft depth.