The WRK project consits of the almost trenchless construction of a pipeline along the A2 highway in the Netherlands. The project involved the design, delivery and construction of a double water pipeline over a length of around 5 kilometres. Additionally, most of the existing pipeline was removed with the exception of the part passing under the A2 highway and the N201/Geuzensloot main road. This part of the existing pipeline was filled up.
Constructing the pipeline involved 24 drillings with a total drilled length of 10 kilometres (for the 5 km double pipeline). The steel pipes had a diameter of 1200 millimetres. Due to the requirements of the district water board, the section under the Geuzensloot canal had the largest diameter, 1500 millimetres, over a length of 200 metres. Here, a pipe casing was drilled. The product pipe was inserted into this casing.
Each drilling started from the drilling pit and arrived in the recovery pit. These pits were constructed using temporary sheet piling retaining walls with a concrete floor. The jacking pit was equipped with frames that were set into the concrete floor to set the machine in motion and absorb the forces from the jacks. Two boreholes in a particular direction were drilled from a single drilling pit. The drilling machines were then turned around and two more boreholes were drilled in the other direction. In total, 2x2 boreholes were drilled from a drilling pit. The total project involved 6 drilling pits and 6 recovery pits.
The boreholes were drilled using the "closed front shield drilling" method using a Herrenknecht AVN 100 drilling machine at a depth of 10 metres below the surface though the Pleistocene sand layer. The soil excavated by the drilling head was mixed with water and then removed in liquid form.