Deepened road layout N242

In Alkmaar, a section of the eastern ring road N242 was constructed below ground level to facilitate a grade-separated junction. For the construction of a viaduct, a decision was made to use a geomembrane construction to create a dry construction site. Heijmans Beton- en Waterbouw BV commissioned Genap to apply a total of 35,500m² of PVC 1.0mm KIWA / ATA geomembrane for this process.

During the excavation of the construction pit, it was found that the sand contained many shells. To protect the future geomembrane construction, Genap first submerged a protective geotextile (non-woven 500gr/m²). Subsequently, the entire geomembrane construction was fabricated into one sheet along the long side of the excavation. Using a self-developed winch system, this geomembrane construction was pulled over the water surface in one day. The geomembrane was sunk using the method of sinking by its own weight. After application, the geomembrane construction was tested for watertightness by TNO using a geoelectric measurement method.