Hello to you all and welcome to this walk at the foot of the Alps. Right in front of you, the result of the disappearance of the glaciers and fed by a mountainous lake basin which guarantees the purity of its waters is the Lake Annecy! The quality of this aquatic complex environment is exceptional.

Thanks to man’s actions, this natural treasure has been protected and now plays an essential role of water resources for about 130 000 people.

Osmoz, here to serve you! I shall be your androguide for the presentation of the water treatment equipments of the Annecy Commune. And now for a bit of history :

In January 2001, by the will of 13 Commune members the Annecy Commune takes responsibility for the production and distribution of drinking water. It so inherits the city of Annecys’ actions which it resumes by adapting a modernisation project of the existing system, as well as the research carried out that meet the new European water quality standards.

Here is the site of Puya. It was chosen in 1906, after two years of debate to accommodate an innovative system of drinking water production from the lake.

The factory of Puya was modernised three times in the XXth century. Its reliability and production capacities have never failed.
This shows how relevant the initial choice of our predecessors is even though it was made more than a century ago.

More than 30 years after the last renovation, it has become necessary to modernise the equipment.
First of all in order to respect sanitary safety requirements, for example in case of accidental pollution due to near by road traffic, but also to ensure that the service will continue to work even if one of the components stops working (by doubling all the water circuits, by increasing the volumes of stored water).

The approach is complex: it has to take into account feasibility and the cost of the project, but also the impact on the environment.
Let’s go and have a look in more detail at the chosen solutions.

The protection area on the lake’s surface has also been enlarged.

An extension of the main building has been built where the former workshops were. In it are the new pumps (more numerous) replacing the equipment among which some are over 30 years old.

The phase of water treatment, then …
The former system included a stage of filtration by means of a micro sieve (which retained the particles in suspension), a stage of oxidation using ozone (which killed parasites, viruses and the other bacteria) and disinfecting by use of chlorine.

The new process of membrane filtration is characterised by the large capacity retain micro-organisms thus avoiding the use of treatment chemicals.
Microsieves have been kept as pre-treatment.

An important safety element is added: a buried reservoir, called " alert tank " in which raw water transits in a measuring station in order to check its quality and for possible pollution before treatment.

Indeed an extension of the current factory in order to install these new filters would have been possible, but not without damaging the landscape.

A place was finally decided upon in the Espagnoux sector, in which to construct the new building. It is at a satisfactory height in order to supply the reservoirs therefore putting an end to the use of the historic pipes under the road, which were to be replaced by an underground gallery. Furthermore, one of the main advantages of this 2nd site is that it is practically invisible from the lake.

The water pumped from La Puya is filtered through a membrane 1,000 times finer than the pores of the skin. Once all the impurities have been removed, the water is stored in an 8,000 m3 reservoir, which brings the amount of water stored to one day’s consumption.

To maintain the quality of the water throughout its journey along the pipes, a tiny amount of chlorine is added.

The new plant is run entirely by programmable automatons, providing greater operational safety.

Particular importance was, of course, given to integrating the Espagnoux building into the landscape…

It was decided to place the majority of the facilities underground and to plant around the emergent parts.

To take the water to the distribution networks, piping was laid between Espagnoux and Belvédère reservoir, which has a regulation system that constantly analyses the water requirements of the supply area.

With this range of facilities, the water board serving the Annecy area has the necessary resources to supply even safer, better quality water.

Furthermore, it is better able to cope with technical incidents affecting the production capacity.

Finally, these new installations have made it possible to extend, in complete safety, the supply of water from the lake, whose low hardness is appreciated by nearly 140,000 residents in the Annecy area.