The Aabach dam in the district of Paderborn (North Rhine-Westphalia), which was commissioned in 1983, is located in the north-eastern foothills of the Sauerland region and has a catchment area of 34.8 km². The barrier structure is a zone dam with a mineral core seal and an upstream sealing carpet. It serves as a drinking water reservoir to supply around 250,000 inhabitants of the districts of Paderborn, Warendorf, Gütersloh and Soest. The drinking water output is up to 11.4 million m3/a. It is also responsible for flood protection measures and contributes to low water enrichment. The owner and operator is the Aabach water board. The barrier structure has drainage facilities at the base of the dam on the air side.
The amount of seepage water is an important indicator of the effectiveness of the sealing of the dam and the subsoil. The position of the surface of the saturated supporting body in the dam (seepage line) is decisive for the load-bearing capacity of the dam. A disproportionate increase in the amount of seepage water produced indicates a change in the position of the seepage line and thus a possible impairment of the load-bearing capacity of the dam. For this reason, the DWA bulletin DWA-M 514 ‘Structural monitoring of dams’ recommends permanent measurement of the seepage water flow for dams over 15 metres high.
At present, the seepage water flow rate is measured once a week in the six existing inspection shafts using a cup measurement. Occupational safety is not guaranteed due to the access to the individual shafts. Redundant measurement of the leachate flow is not possible. The current situation therefore does not comply with the principles for the safety monitoring of dams in accordance with DIN 19700-10 and -11. The measuring system is therefore to be modified so that a permanent, automatic, weather-dependent measurement of the quantity of seepage water is possible. The measurement should be possible with a high degree of accuracy both for larger discharges from the dam via the bottom outlet or via the spillway (HWE), but the very small quantities of seepage water previously recorded manually should also be recorded with corresponding accuracy.
The measurement results are to be recorded automatically and transferred to the dam's process control system with the option of alarm functions. The aim is to improve occupational safety for the regular inspections by bringing the seepage water pipes together in more ergonomically favourable measuring structures. From there, the measuring equipment can be maintained in a centralised manner.
Client: Aabach water board
Processing period: 2021 – currently
Main data:
Construction period: 1975 - 1979
Height of the barrier: 45 m
Capacity: 20.45 million m³
Services:
Site consultation
Basic investigation
Development of a planning concept with variant analysis and development of a preferred variant
Project planning of engineering structures, work phases 3-6
Specialist planning for structural engineering, work phases 3-6
Specialist planning of technical equipment, work phases 3-6