The project concerned is a Market Hall in the city centre of Rotterdam, where a covered market with 228 apartments will be constructed. More importantly, the complex will include an underground 4-storey car park. The contractor had to dig the site to the right depth – no easy job due to the presence of 2.500 piles. Moreover, the bottom of the excavation site was pure clay, which is notoriously difficult to dredge.
Damen Dredging Equipment offered the solution by fitting out a standard DOP1515 with a specially adapted disk-knife cutter. The disk-knife cutter, which has long vertical blades, already existed yet was made to measure in this project using the input of the contractor. The unit – fit for the confined spaces between the piles –is a hydraulically driven adaptor connected to the DOP1515. It cuts the clay in layers yet the design is such that it does not damage the piles. The mixture is pumped to the nearby dewatering station.
The DOP1515 is connected to a Martens en van Oord crane; both the 65 kW dredge pump as well as the disk-knife cutting unit run on the crane’s hydraulic system. The max mixture capacity of the DOP1515 is 500 m3/hour, it worked at a max dredging depth of 14m on a D-200mm discharge pipe line. Martens & van Oord owns a number of DOP pumps, two of which are working on the Market Hall project with a disk-knife cutter each.
Martens & van Oord and Damen Dredging Equipment took up the challenge in January this year. The disk-knife cutter was engineered and manufactured rapidly and has proven to be highly successful – 2 identical units are now finishing the job, so that the construction works on the underground car park can start soon.