Strandkai district, Hamburg-HafenCity

Located opposite the Elbphilharmonie concert hall on the banks of the Elbe River, the Strandkai district in Hamburg’s HafenCity is one of the most sought-after residential locations in the Hanseatic city. After almost 15 years of construction, the development of around 14,000m² of land west of the Marco Polo Tower and the Unilever building marks the completion of the new district. Stump-Franki was commissioned by August Prien Projektentwicklung and DC Developments to produce the entire construction pit with pile foundations, secure the surrounding buildings, and seal and secure the quay walls facing the Elbe.

From luxury lofts to rent-controlled flats

The Strandkai district is located on a peninsula enclosed on three sides by the waters of the Elbe. An undeveloped area of 97m will remain on the quay tip and be turned into a public space. A vibrant mix of 475 residential units has been planned for the remaining vacant building plots. They are distributed across two luxury residential towers and two perimeter block developments with owner-occupied homes and rent-controlled flats. A children’s cultural centre, or “KinderKulturHaus”, a permanent exhibition entitled “Fairytale Worlds – The Legacy of the Brothers Grimm”, and retail and catering outlets will move into the ground floor and the lower floor situated in the anti-flood mound, known in the local tongue as a “warft”.

Dedicated to anti-flood protection

The property is located in a high flood risk zone. The groundwater level is subject to tidal influences.

Even though most of the construction area was sealed off from the Elbe by the old quay walls, the construction pit was secured with 5,600m² of sheet piling on the west and south sides and 1,564 jet-grout columns were used to further seal off the areas between the sheet pile profiles. The east side was secured by 640m² of bored pile wall with inner bracing. An anti-flood mound was built in the construction area to secure the site facilities and equipment in case of flooding.

Secure pile foundations

The shared underground car park under the four buildings was founded on partial displacement bored piles with the aid of a Fundex drilling rig. The Stump-Franki team placed a total of 1,610 piles in the medium-dense to dense sands below the soft strata and drilled an additional 200 clearance holes in the area where the existing structures were located.

There were a number of special requirements: for one, the team had to carry out the work without damaging the anchors that were already in the subsoil. They also had to keep a constant eye on flood forecasts. In addition, an emergency plan was in place in case of a storm surge.

Execution planning and realisation from a single source

The subsidiary Stump-Franki Planung was responsible for the approval and execution planning of the pile foundation and for the works and installation planning of the construction pit walls. Working in tandem, the two companies realised the project successfully and safely.