High Acceptance and Ideal Operations

The underground construction was mainly a result of the location question. Between 1976 and 1990, Castlunger (from Bruneck), a consulting engineering firm commissioned with the planning and supervising of the construction works, examined ten locations.
Yet, none of these locations were accepted by the population. As Central Puster Valley is a tourist area and the river Rienz flows through the entire Puster Valley, the catchment area of the Central Puster Valley could no longer afford to pollute the river Rienz.
Thus, the idea was born to build the Central Puster Valley associated wastewater treatment plant as a cavern plant.

Advantages of building underground:

- The preservation of valuable cultural landscape, which is scarce in the narrow Alpine valleys;
- Construction work independent of weather conditions;
- High acceptance with the population: Out of sight, out of mind.;
- No odour emissions due to central ventilation system;
- No difficulties during winter-time operations (icing, snow, frost);
- No difficulties due to the wind (aerosol or mould sludge extraction);
- No algae in the sewers and basins as there is no sunlight;
- Longer duration of the constructional layout and mechanical structures since the temperatures are constant and the plant is uneffected by the weather. The lead-in can be executed in free fall, whereas other constructional versions would have required a pumping station.


Drawbacks of underground construction:

- Higher construction costs due to rock excavation, rock stabilisation and support system;
- Higher operating costs due to the ventilation system in the galleries.