EN 
DE 
Gundlach GmbH & Co. KG is planning the construction of a new residential development with two apartment buildings with up to eight upper floors above a shared underground car park in the List district of Hanover. The site is located at the corner of Klopstockstraße and Günther-Wagner-Allee. The property is part of the former Pelikan site, on which the company Günther Wagner (later Pelikan AG) manufactured office supplies (paints, inks, copying paper, etc.) from around 1906. The area has a size of approx. 2,200 m². In the 1990s, parts of the factory site were demolished and developed into a residential and service quarter in the course of various project developments.
M&P Hannover was commissioned with the preliminary planning of the excavation pit incl. the services for the planning of the explosive ordnance clearance and the soil management / contaminated site remediation.
For the construction of the planned underground car park, excavation depths of up to max. 8.1 m below ground level were required. In the area of the car lift underpasses, the maximum excavation depth was approx. 10.1 m. Numerous production residues from Pelikan AG were discovered during the excavation.
Due to the narrow space conditions and the depth of the excavation pits, the excavation pit was secured with a mixed-in-place shoring wall (MIP) from Bauer. The shoring wall was tied back, and two anchor levels were necessary in the area of the car lifts. The chalk clay formed the lower pit seal. The shoring wall with a length of approx. 20 m was embedded at least 2.0 m into the groundwater dam, the chalk clay. In this way, the water ingress was reduced to a minimum compared to a horizontal sealing. Residual water retention was ensured with the help of 10 wells.