This operation involved driving a narrow tunnel (20 m long by 1.5 m square) through a rock ledge for a sewage pipe.
Two houses had been built on the rock ledge. For this reason explosives could not be used. Similarly, large mechanical demolition tools would not fit in the narrow tunnel. The rock was also too hard for a Hand-held demolition hammer.
Only with a Darda hydraulic rock and concrete splitter was it possible to excavate the tunnel without creating dust, noise or vibrations and without putting the houses at risk. furthermoer, the splitter was able to break down the hard rock without difficulty since the Darda splitter applies force inside the material itself. In this case, one C 11 SL splitting cylinder and a mobile A1-type compressed air motor unit were used. Two workers carried out the drilling and splitting, while a third removed the pieces of rock. They completed the tunnel in just under forty days.