Construction of retention reservoirs at the port of Gdańsk, the purpose of which is the temporary retention of rainwater and snowmelt from investment areas, the so-called Pomeranian Investment Centre. Retencjapl was involved in the project from the concept, through construction and executive designs, to author’s supervision.
The Gdańsk Economic Development Agency, in accordance with the Local Spatial Development Plan , allocated the area at the port of Gdańsk for warehouse yards and logistics bases. 90% sealing of the area, which is currently covered by wasteland and forest, was allowed. At the same time, the administrator of the watercourse, to which rainwater goes, imposed in technical conditions extremely strict limits for the discharge of rainwater into the ditch and watercourse, because receivers during heavy rainfall are already heavily overloaded. The challenge of the concept, based on the analysis on the hydro-dynamic model, was to obtain low values of the temporary maximum runoff of rainwater with a high degree of sealing the area (90%!). In the original intentions of the investor, it seemed that clearing the forest for the retention reservoir was unavoidable. An additional difficulty was the type of soil, which made it difficult to compact the embankments mechanically.
We analyzed a number of precipitation scenarios to design the appropriate drainage and retention method. The sequential arrangement of the reservoirs and the proper method of making the escarpments made it possible not only to save the forest, but also to retain water economically and effectively. The designed reservoirs required specific engineering work: from the selection of technology for making embankments in difficult terrain (overload embankment), through the creation and analysis of the hydrodynamic model of the entire drainage system, to the adaptation of construction solutions at a high groundwater table. The reservoirs have been built and a recreational path surrounds them.
The designed and built system of dry tanks is unique, both in terms of scale and method of execution. Thanks to the use of smart, but also low-cost, geotechnical methods and exceptional care of designers, it was possible to save the trees that currently grow in the middle of the reservoir. The reservoirs are perfectly inscribed in the landscape, one is actually a flower meadow, and the other a depression in the forest, they do not stand out from the surroundings at all, while protecting the area in the event of even 1% water.
Main benefits: The investor can achieve his business goals and seal the area for storage yards and warehouses, but he does so with respect for the environment and ensuring flood safety. We saved the forest!