Rotermann Quarter underground garage in Tallinn
The Rotermann Quarter is a former industrial area in the heart of Tallinn, Estonia that has been given a new life as a modern shopping, entertainment, business and residential zone.
Our engineers' special skills were needed when creating a two-level underground parking garage underneath the valuable heritage site with weak soil and fragile historic structures overhead. The parking garage was built the same time as three new shop, office and apartment structures were being built directly overhead, one of them within the old façade of a salvaged building.
New solutions in Estonia
The area, locating about 500 meters from the Tallinn Bay, is old seabed with soft, weak soil layers and an unusually high groundwater table at 1.5 to 2 metres from the ground. The garage's base slab is nearly seven metres below groundwater level, so the enormous pressure had to be overcome. As part of the solution we installed the sheet piles that surround the excavation as the site's permanent structure – the first for a similarly-designed underground parking garage project in Estonia. Pumps and drainage systems also played a role.
It was also essential to keep vibrations to a minimum to prevent soil displacement and damage to the buildings above and nearby. We used a special low-vibration press to install the sheet piles, and placed sensors and hundreds of geodetical measurement points to nearby buildings to monitor the situation.
A 53-metre brick chimney standing directly atop the future garage area was something the team worried about most. A combination of load-bearing support piles forming a retaining wall and tension strands was used to take the loads and keep the chimney stable.