During the maintenance works near the Hooglandgemaal in Stavoren, Wetterskipn Frieseland, plastic dam walls were used for the very first time. According to Project Leader Jan Sipma this has quite some advantages: “Plastic has a much longer lifespan, and is easier to insert. As a result, the total costs are lower. Furthermore, it is a sustainable product, made from 100% recycled plastic.”
The plastic dam walls are manufactured by Prolock, which offers a variety of systems, all depending on the actual situation. The common denominator is a patented combination of 100% recycled plastic plates and untreated softwood piles. The screen retains the soil and the longer wood piles provide the required firmness and stiffness to the construction. The combination of shorter screens and longer piles represent substantial savings on material costs. Furthermore, the lifespan of a Prolock system is fifty years as a minimum, which is three times as long as the lifespan of a hardwood alternative.
Jan Sipma was introduced to Prolock when visiting a trade fair, and he was intrigued by the potential. Following a number of discussions with the manufacturer Profextru, it was decided to use it in the shoulder of a dike and along the bank with a length of approximately 300 metres. “The aim is to have minimum maintenance, for the lowest costs possible. In my view, this is how we can achieve this.”
Excellent sealing. According to Henry Hoekman of Profextru an increasing number of water boards, municipalities and authorities now select this system. “They are not only interested in the fast insertion and the attractive price-quality ratio, but it is also the environmental aspect that counts. We use one hundred percent recycled plastic, which can at least be reused six more times. This means our product fully complies with the cradle-to-cradle principle.” Chris Nagelhout of the construction company Nagelhout Woudsend B.V. can confirm that the system can indeed be inserted in short time. The company organises the insertion for the Wetterskip, but has been working with Prolock for approx. five years itself. “The plates are rather thin, meaning they can easily be inserted in the soil, it allows you to work faster”, explains Chris.
“When compared to a wooden dam wall, you can use shorter plates, since the longer wooden piles ensure firmness and stability. I am very positive about this; it is an excellent product, easy to process, and the duality is perfect.” According to Nagelhout, one of the advantages is the sealing. “If you install a wooden dam wall with a spring and groove, it could occur that it opens slightly, meaning it is not fully closed. This can be solved at a later time, but still, it is complicated. This system absolutely does not present this issue. You simply slide the parts into one another from the top, which is why it does not ‘run away’, and thus results in an excellent sealing.” Chris Nagelhout states that it is all in the eye of the beholder when confronted with the fact that plastic has a less attractive appearance in a natural environment. “The largest part will be in the soil, and the section that extends above the water level represents a perfectly finished total. Prolock also allows you to make excellent bends. This could be done with wood as well, but that requires a slightly higher level of creativity.” Jan Sipma assumes there are many biased ideas about this product. “But I am convinced: it i a more sustainable product, with a much longer lifespan when compared to hardwood, and it is virtually maintenance-free. In short, a responsible decision with attention for the environment and costs.”