execution of construction work Tobl

Together faster to the end

The consortium of contractors from the Autonomous Province of Bolzano-South Tyrol was commissioned with the basic procurement, planning and construction.
The consortium of contractors is an association of qualified local construction companies with the aim of increasing performance and competitiveness.

Time lapse:


- Selection of the six construction companies by the South Tyrolean construction consortium
- Decision of the Provincial Government
- Decision to award in concession
- Convention to the construction consortium


- Signature of the Convention
- official authorisation
- First blasting
- Milling of the infeed tunnel by ILLBAU

1992-1993 - Excavation after NÖT in the three caverns
1993-1994 - Concrete work: 50.000m3
- Reinforcing steel: approx. 1500 tons

- Assembly of the electrical and mechanical equipment
- Timely release of the systems for functional testing

03.07.1996 - Punctual commissioning after completion of the functional tests
1998 - Commissioning of sewage sludge drying plant
2004-2005 - Construction and commissioning of the thermal sewage sludge utilisation plant
2008 - neue Bandtrocknungsanlage

Tunnel construction

The excavation as well as the securing and extension works were carried out according to the Austrian tunnel construction method (NÖT). The lining was carried out in two phases, shotcrete and expansion anchors or mortar anchors, reinforcement mats and shotcrete. The rock reinforcement acted as a permanent load-bearing element ("single-shell lining"), which placed higher demands on the quality of the materials and the execution. 13 measuring stations (convergence measurements with five convergence bolts each, multiple extensiometers, levelling etc.) were installed for the metrological monitoring of the lining work. Construction was carried out around the clock in 3-shift operation.

Tunnel construction

Tunnel construction

Safety and extension measures

"Single-shell removal": the rock protection acts as a permanent load-bearing element.


- 2-5 cm shotcrete (sealing)
- 1st layer: shotcrete 10-15 cm, reinforcement mat diam. 5/20/20, mortar anchor, N = 4,5 - 6,0 - 7,50 m weight bar diam. 28 mm
- 2nd layer: shotcrete 10 cm HS cement, reinforcement mat, diam. 5/20/20

Safety and extension measures

safety measures

Structural structure wall - rock

The Inlet Tunnel

The intake tunnel, with a diameter of 3.9 m and a length of 930 m, was milled and at the same time served as an exploration tunnel. In the area where the Gader River flows into the Rienz River, the individual sewers are fed into the intake structure of the intake tunnel. Due to the depth of the canals (5.0 m below the water level), extensive drainage work was necessary.

Structural structure wall - rock

Section: wall rock construction


Technical data caverns:

Total outbreak: ca. 200.000m³
securing area:
ca. 50.000m³
Sprayed concrete:
ca. 12.000m³
Armature: ca. 50.000m
Steel mats: ca. 200.000kg
Explosives consumption: ca. 150.000kg
levelling concrete: ca. 2.000m³
Structural concrete: ca. 22.000m³
Reinforcing steel: ca. 1.500.000kg
Formwork: ca. 50.000m²

a) central gallery

b) side galleries