From the beginning of May, 2015 till the end of February, 2016 a sewer was jacked under the „Fallerovo Promenade“ near the city centre of Zagreb and it was connected to the existing canal-system.
The inside diameter of the canal, constructed of glass fiber reinforced plastic (GRP) pipes, was 2080 mm with an external diameter of 2250 mm.
The total length of the canal under the promenade amounted to approx. 1000 m and the major part of the segment (approx. 900 m) was executed in open shield technology. The entire jacking consisted of 5 sections, the longest reaching about 250 m. A total of 7 excavation pits had to be provided for the mining work and 1 double-press pit, 2 start pits, 1 start / aim pit and 3 aim pits were needed.
After the completion of the 2000 canal another 3 crosscuts with GRP pipes (DN 1050 / DA 1100) were conducted via microtunneling. The segments approached 20 m each and were jacked through under an existing stream.
The geology to be expected consisted of sand / gravel with partially silty and argillaceous overburden layers.