The goal is to make Länsiranta a pleasant and durable coastal area for residents, passers-by and entrepreneurs equally. The LUCIA project has a significant role in the planning and implementation of the area. The lighting and the technology implemented in the LUCIA project will be seen by everyone moving about the area in little over a year. However, the preparations that need to be done in the area will be invisible to many.
Länsiranta consists of old seabed and river delta. The soil is deep and soggy clay both in the river delta and the entire Länsiranta area to be built. The soil is best described as ‘yoghurt’. At its best, or worst, the ‘yoghurt’ soil extends to the depth of 25 metres. Just imagine building something on that!
In the past, Länsiranta was an industrial zone. Because of this, the soil in Länsiranta is not only yoghurt but spoiled yoghurt. To build a pleasant and durable green area on this partially contaminated soil, the subsoil needs to be restored and hardened to carry the weight. The contaminated soil on the surface can be dug out and moved away, but the soggy clay will remain in place. It needs to be hardened and stabilised with pillars.
Soggy clay soil does not only involve sinking and contamination; we also need to ensure local stability so that the entire building mass of Länsiranta will not fall into the river once the clay bank gains weight from the new constructions. This has been partially solved earlier by stabilising a wall into the clay near the bank. It provides lateral support to the entire bank. This existing wall can be partially used in the LUCIA project, as well. However, there are spaces between the wall and the existing city quarter for which we need to plan and implement further stabilisation.
In practice, stabilisation means whisking hardening materials into the soil in pillar-shaped portions. Geotechnicians will define the binding agent recipes, dimensions of the pillars and plans for the stabilisation contractor. The city will order plans from the geotechnicians, hold a bidding competition for stabilisation contractors, supervise the work and then wait for the pillars to harden before anything else can be built in the area. This means that the stabilisation work will take more than six months.
The time and money contributed to the stabilisation process will not be visible to the general public. In the future, not many people walking on the LUCIA path will think about the secret below the surface in Länsiranta.