Drainage Zug north, main channel to the lake
Go Bau AG performed as overall and chief construction manager for the phases from preliminary project to commissioning – in both major projects on behalf of BG Ingenieure + Berater AG. Marc Reinhard was the direct contact person for both representatives of the clients (Stadtentwässerung Zug and Wasserwerke Zug AG). He led the project planning team at BG Ingenieure + Berater AG as well as the regular project planning and construction meetings in both projects.
At a depth of eight meters below the city of Zug, a drainage canal for meteoric water was realized for about one third of the city’s area. With a diameter of 2.7 meters and a length of 1.8 kilometers, it was one of the largest projects of its kind in Europe. The “main pre-flood pipeline Zugersee”, which esd built in this project, had an “aorta” function for the city drainage system. It was to convey the unpolluted rainwater from the densely built-up area of Zug North into Lake Zug.
Along the same axis, the Zug energy supply company WWZ was building the first sections of the Circulago heating and cooling network, which uses the energy in the water of Lake Zug. Lake water is collected 400 meters from the shore and transported via a pipeline to the underground lake water center in Schützenmatt. There, the energy in the lake water is transferred to a second, closed network of pipes by means of heat exchangers. These pipes transport the energy to the energy centers in the neighborhoods. There, the heat is generated by heat pumps and distributed to the connected properties via a conventional district heating network. The cooling is provided to the customers by direct re-cooling via a separate district cooling network. The development of Zug and Baar-Süd was carried out in several stages based on customer requirements. Coordination of the initial Circulago pipeline sections with the city’s drainage project offered considerable advantages: The pipelines laid in a tunnel running parallel to the receiving water pipeline could be routed to the Gubelstrasse/Industriestrasse axis via Schützenmatt and the Aabach traffic circle within a useful period, which prevented any additional construction emissions and traffic obstructions.
Before microtunnelling started, for both projects shafts had to be constructed at six different points in the north of the city of Zug. There the tunnel drilling machine could start or finish its work. From the shaft of Aabach traffic, drilling proceeded in the direction of the lake (L≈360m) and the target shaft Gubelstrasse (L≈590m). Afterwards, the microtunnelling method was applied from the shaft Göblistrasse along Industriestrasse to the target shaft Gotthardstrasse (L≈880m). After the start and target shafts have fulfilled their tasks, they’ve been formed and used as shaft structures.
Construction Method Microtunnelling:
Trenchless pipeline construction with diameters of up to 3000 mm, was realized with the help of Microtunnelling. Drilling was executed with a tunnel drilling machine like the one used for the construction of the Gotthard Base Tunnel – of course on a much smaller scale. In recent years, technology of unmanned mining has made great progress. Electronic devices and sensors control and monitor the excavations. Curved sections can also be carried out with this technology. Controllable full-face cutting machines excavate the material during microtunneling. The drill head drive is usually located directly in the excavation machine. Otherwise, the procedure is the same as for press tunneling. In the Zug North drainage construction project, a system with wet conveying was used, which found its way underground in this special ground with a high groundwater table.