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Can Vinyl Sheet Piling Live Up to its Green Potential? Exploring Production, Use, and Disposal
Climate changes have been progressing at an increased pace. Climate changes have been progressing at an increased pace. According to the data gathered by the UE Copernicus Climate Change Service, 2023 has witnessed an unparalleled surge in global temperatures, setting a new record with an average annual value of 14.98°C, surpassing the previous high in 2016 by 0.17°C [1]. When taking measures to deal with such intensifying phenomena which take on a global character, it is necessary not only to effectively mitigate the consequences of climate change, but also to select tools and methods that will minimize the negative impact of the remedial activities carried out on the environment. In light of the above, vinyl sheet piling used in civil engineering and hydrotechnical investments seem to be of the solutions worth considering because of their low carbon footprint and the fact that they are manufactured from recycled material.
The effects of rising air temperature are on one hand flash floods and inundations as a result of heavy rainfalls and, on the other hand, long dry periods which lead to large scale draughts.
In this article, we present the environmental aspects of vinyl sheet piling manufactured from recycled material in Poland by the Pietrucha Group where 100% of energy used in the production comes from renewable energy sources. Contrary to steel sheet piling, the use of PVC profiles in hydrotechnical and civil engineering projects is marked by significantly lower greenhouse gases emissions, lower use of natural resources and minimal impact on the local ecosystems and human health.
PVC or steel? Comparative analysis of environmental impact
Scientists from the Faculty of Industrial Ecology of the Łódź Technical University have carried out comparative life cycle assessment (LCA) of vinyl sheet piling and steel sheet piling and subsequently have calculated the carbon footprint of the two products [2]. LCA is one of the most advanced environmental management tools included in the international standards ISO 14000. This tool is used to determine the environmental impact of the various phases of a product's life cycle (from extraction of the resources needed to manufacture the product to its disposal). The reference value (the so-called functional unit) for which the environmental impact is determined is often the unit of the manufactured product or the unit function it performs. The life cycle assessment methodology represents a very broad approach of environmental impact – from the cradle to the grave. As the cradle, the processes of extraction of natural resources are most often assumed, while the processes of waste disposal are the grave.
The analysis was based on the following assumptions: five metre long profiles are manufactured in Poland and then transported to the Netherlands to be used in a construction intended to protect a 500 metre embankment of a canal. According to the investor, the construction was intended to last for 50 years. For the purpose of the analysis, the most popular GW 610/6,4 pvc profile was used, since the width, strength parameter and low weight of this profile type is ideal for such applications. As far as the steel profiles are concerned, two types of profiles differing in wall thickness were compared 7 mm and 13 mm. The thicker steel sheet piling is used in projects where they are exposed to expedited corrosion due to differing water level. The amount of transport units required to deliver the defined quantity of profiles is presented in Table 1 below.
It was assumed that the means of transport of raw materials as well as products and waste (dismantled sheet piles) are lorries with a load capacity of 24 tons and the vehicles meet the EURO 4 emission standard and are used in European conditions. The outstanding data used for assessment was based on the latest data from reports on the consumption of energy at the raw material production and processing as well as during the manufacturing of the respective profiles. The analysis of the environmental impact was made using the SimaPro 7.3.0. software and the normalization indicators have been determined using ReCiPe Endpoint (H) for three endpoints:
- Human health
- Ecosystems
- Resources
The above indicators do not have a unit because the determined environmental impact is divided by a reference value expressed in the same unit in the normalization procedure. The indicator units constitute dimensionless values. Additionally, the environmental impact assessment was also determined by the carbon footprint method, understood as the total sum of the greenhouse gas emissions caused directly or indirectly by a product. The emission unit is 1t of carbon dioxide equivalent (CO2 eq).
The analysis has proved that environmental impact of steel sheet piles is from 207% to 807% higher than the one calculated for polyvinyl chloride sheet piles used in the same project.
Vinyl sheet piling serve the nature well: projects overview
Over the past years, vinyl sheet piling were in majority used to construct cut-off walls, for example to reinforce the water-tightness of flood embankments. Such projects have been carried out as part of actions undertaken to prevent the climate change consequences which are becoming more and more intense. When coupled with rapid urbanization, the adverse consequences of climate, change, such as floods, are threatening densely populated regions of the globe. As the area requiring prompt environmental action is expanding and more and more people are becoming afflicted by adverse consequences of climate change, the design engineers have started to look for solutions and technologies that would have low environmental impact when used in projects intended to protect the environment. This tendency, which has resulted in the growing popularity of vinyl sheet piles, allows for instant mitigation of threat with the simultaneous care about the future generations by way of minimizing the mid- and long-term environmental impact. The results of the LCA analysis referred to above, serve as a perfect confirmation of the above.
Innovative bird islands
The project LIFE.VISTULA.PL carried out in the area of the Goczałkowice Reservoir and the adjacent ponds, included in the Natura 2000 zone, serves as an excellent example of the arguments referred to above [3]. The main objective of the project supervised by the Regional Environmental Office in Katowice was the protection and improvement of the nesting grounds for 100% of population of night heron and 7% of population of common tern in the Upper Vistula River region. In this project, the vinyl sheet piling was used to reinforce causeways and especially to construct artificial islands for birds. The water level where the birds traditionally nested in dry season was very low, but in later months, due to heavy rainfall, the water level was rapidly and radically increasing causing damage to the nests. The crown of the wall made of PVC piles was erected 3 metres above the bottom of the reservoir. The construction was reinforced with special external rings and steel ties were installed in one of the rings (Picture 2).
As a result an island was created where the birds may safely nest during the peak water level at the Goczałkowice Reservoir (Picture 3).
Addressing the varying ground water level in a nature reserve
Vinyl sheet piles were also used in the Białe Ługi reserve in the Świętokrzyskie Voivodeship in Southern Poland, which is also included in the Natura 2000 zone. As a result of the progressing climate change and aggressive drainage, the reserve suffered from rapid lowering of ground water level, which caused degeneration of animal habitat. In order to address this environmental catastrophe, the Regional Environmental Office in Kielce decided to use vinyl sheet piling to prevent the ground water outflow and drainage in this valuable ecosystem [4].
In conclusion, it is worth highlighting that vinyl sheet piles are highly resistant to environmental factors, including UV radiation and acidic environment and may successfully be applied in innovative applications.
Literature:
- https://climate.copernicus.eu
- Materials provided by S. i A. Pietrucha Sp. z o.o.
- http://lifevistula.pl/o-projekcie
- https://kielce.wyborcza.pl/kielce/7,47262,27702047,nietypowa-inwestycja-na-terenie-rezerwatu-przyrody-ma-zatrzymac.html