Vinyl sheet piles used to construct flood protection infrastructure in a urbanized area
When planning new developments within cities, one of the biggest challenges is fitting such investments and their accompanying infrastructure into the existing urban fabric, so that the development does not impact the existing balance. The Złocień residential estate in Cracow is one example of where unthoughtful planning has led to serious consequences, with floods on the estate being the result. However, thanks to the implementation of modern technologies and materials, the situation was successfully addressed. In this article, we analyze how the application of the EcoLock vinyl sheet pile technology by Pietrucha protected the residents of Złocień and helped generate considerable savings on the remedy works.
Large metropolitan cities in Poland are consistently increasing in size, taking over more and more area that were not previously considered suitable for development. A serious challenge when planning such investments is fitting new residential estates and the accompanying infrastructure into the existing urban fabric, so that the development does not disturb the existing balance. Unfortunately, such undertakings are not always successful as one may learn from the example of the Złocień residential estate located in the Bieżanów-Prokocim district of Cracow.
The Złocień estate is located in the Serafa River valley. Until recently, the area mostly consisted of arable land and detached houses built mainly in the 1918-1939 period. Due to the rapidly progressing and ill-considered development, new residential estates which were built north of the Serafa River, on its left bank, were periodically affected by small floods, which resulted from the specificity of the terrain and the surface run-off of the rainwater during heavy rains down the concrete paving stones straight to the underground garages.
As more and more settlements were built along the left bank of the Serafa, the problem also appeared on the right bank of the river. As a result of the conducted expertise, it was found that the direct cause of this phenomenon is the construction of a fence with an 80 cm high concrete foundation around one of the housing estates on the left bank of the Serafa, which was an effective barrier to water during floods in the river.
As a result, the water could not flow in its natural direction, where until recently farmland was located. Instead, the water started to overflow to the area located on the right side of the river. The problem is that the houses built several decades ago on the right bank of the Serafa had no protection against flooding, as this problem had never occurred there before. The greatest flooding occurred in 2021, when the amount of precipitation in Krakow was the highest for at least 160 years (measurements have been carried out since then).
As a result of an expertise commissioned by the Polish Waters (Wody Polskie), it was found that the problem lied in the concrete foundation of the fence mentioned above. A method was proposed to protect the right bank against flooding by building a structure designed to enhance the capability of piling up water during floods and to increase the river bed capacity. However, the existing buildings and old trees with a densely developed root systems posed a considerable problem in carrying out the task. That is why, it was decided to apply the EcoLock vinyl sheet piling technology, since the installation of vinyl sheet is very fast and requires the least space. What is more, as compared to other considered technologies, vinyl sheet piles were the least expensive and the most environmentally friendly solution.
Vinyl sheet piles technology i.e. how all challenges were addressed
The remedy to the aggravating problem was the reinforcement of the river embankment with a wall made of vinyl sheet piles, so that the crown of the wall protruded 1.10m above the level of the terrain. However, the base of embankment was situated on very diverse and weak soil and the embankment was created rather spontaneously over the years by the local inhabiants who brought soil and placed sandbags on the riverbank. With time the sandbags eventually disintegrated and vegetation grew on it. That is why, it was decided that vinyl sheet piles would not only protect the area above its level but also 2 meters below, so that the construciton would not be washed away during longer floods. In order to provide additional protection, vinyl sheet profiles equipped with an integrated gasket made of soft PVC were selected to ensure the tightness at the lock connections. Vinyl sheet piles with gaskets are an innovative solution developed by the Pietrucha Group, which allows for immediate tightness, contrary to the traditional steel sheet piles which require time and costs consuming procedures conducted on site to achieve the result, which would consist in applying chemical substances or by welding the locks.
Following a static and economic analysis, it was decided that the recommended type of profile from the Pietrucha Group comprehensive portfolio would be GW-610/9 with a length of 3m. A total of 1286 m2 of sheet piles and 510 m of vinyl cap were used for the entire task.
An added value: cutting 1/3 of the costs
Comparing the costs of vinyl walls alone to steel sheet pile walls that could be used for this project, it can be concluded that the cost of the material alone in the budget of the ordering party amounted to about PLN 400,000. It should be added that in the case of steel sheet piles, double-sided anti-corrosion protection would also be required. Based on the market prices, the selection of vinyl sheet piliing technology helped generate savings of around PLN 600,000.
With the total project budget of PLN 2,000,000, the choice of vinyl sheet piles aloowed for cutting the costs by nearly one third!
Fot. 4 and 5 the EcoLock GW-610/9 vinyl profiles used to reinforce the right embankment of the Serafa River adjacent to the Złocień estate.