“An exemplary project for water and agricultural land”

The municipality of Grimisuat won the #prixalpiq 2024 for the redevelopment of the Etang de Revouire, a damming structure essential for water management within its territory. Raphaël Vuigner, President of the municipality, discusses this winning project.

What is the backdrop to the project awarded last year’s #prixalpiq?

Our municipality has no direct water resources within its territory. It therefore depends entirely on external sources, which it shares with other municipalities. The Etang de Revouire was built in 1947 to retain some of the waters of the River Sionne and the Rawyl dam by means of a bisse, or irrigation channel, more than eight kilometres long. This structure is essential for water management in Grimisuat, as it allows us to ensure its availability during the driest periods. It now has a storage capacity of 50,000 m³ to supply a network used for the irrigation of around 170 hectares of vineyards and 90 hectares of meadow, as well as private watering needs. The volume of water used during the irrigation period is about four times the capacity of the pond, or about 200,000 m³.

Taking part in the #prixalpiq in 2024 was an opportunity to give us great visibility and ensure that our project could serve as an example for other municipalities.

Raphaël Vuigner, President of Grimisuat

What did winning the #prixalpiq bring to Grimisuat?

Taking part in the #prixalpiq in 2024 was an opportunity to give us great visibility and ensure that our project could serve as an example for other municipalities. And many of them responded: “If Grimisuat did it, why not us?” Several municipal presidents have already contacted me; they know that it is not easy. The sum of CHF 40,000 allocated to us is particularly important for this type of competition. In particular, we will use it to communicate about our sustainable and efficient water management. Part of this money has already allowed us to set up a photo exhibition of the construction site, next to the Etang de Revouire. There are a lot of walkers and cyclists in this area and these images are compelling.

What is the status of the project?

We put the water back in the pond on 1 April. It took a week for it to fill up, even though we don’t need it to be full for now. It then took a week for the soil and deposits to settle at the bottom of the pond. This step is important to avoid clogging the filters located at the outlet of the reservoir. Everything has been ready for operation since 15 April.

What is this project about?

The Etang de Revouire had lost nearly 20,000 m³ of its original volume due to soil and sediment deposition. Moreover, its earth dam was no longer watertight. It was therefore necessary to excavate and recycle these materials and review the water tightness of the pond (see also below). We also wanted to anticipate the periods of extreme drought that await us due to climate change. As a result, we have increased the volume of water storage in our municipality by almost 30%. The project also includes the implementation of a comprehensive irrigation concept with a view to developing less water-intensive systems and reducing leakage and losses. This represents a total investment of just under CHF 4 million. Our redevelopment project is quite exceptional! We have also received support from the Confederation and the Canton of Valais, which promote this type of exemplary investment.

What is the recipe for your success?

We took a holistic approach and showed from the outset that this work would bring added value not only in terms of water storage, but also for agricultural land. We included all relevant stakeholders in our discussions, including farmers who own land in the municipality, all departments of the State of Valais, the Federal Office of Agriculture and environmental associations. Furthermore, we collaborated with several specialist design firms to ensure that we had every chance of obtaining the approval of the Canton and the Confederation.

Work carried out quickly

Saturated by deposits, the capacity of the Revouire storage reservoir had declined substantially over time. To remedy this, the municipality of Grimisuat carried out dredging and sealing work. Explanations.

Preliminary work

Work was carried out in autumn 2021 to make the pond more secure. The redevelopment project was studied in 2022 and approved in the summer of 2023. In spring 2023, the municipality of Grimisuat carried out a pilot project on the Coméraz secondary pond. With a capacity of 650 m³, it also required refurbishment.

Nearly 20,000 m³ of recycled materials

The dredging work on the Etang de Revouire began in November 2023, after it had been completely emptied. Once extracted from the pond, nearly 20,000 m³ of earth and sediments were deposited nearby in the agricultural area. The slightly polluted materials were treated on site using a pilot land farming process (or aerobic biodegradation). Finally, most of the excavated materials were reclaimed across about 7,000 m² of surrounding meadowland to avoid it needing to be evacuated by truck.

Natural landscaping

Work has now resumed following a temporary restoration of water for the summer of 2024, and a subsequent draining procedure at the beginning of October. In order to avoid loss by infiltration through the earth dam and the rock faults (estimated at 15%), the bottom of the pond was covered with two tarpaulins. The finishes carried out at the same time made it possible to restore a natural appearance to the pond and its banks. They will also protect the pond lining from UV rays. The water was returned to the pond in April.

What is it?

A competition that supports the municipalities in the Canton of Valais in the development of specific projects focussing on sustainable water management, be it in the fields of agriculture, the environment, energy, tourism, culture or others.

Who is it for?

Municipalities, companies, start-ups, research centres, students and freelancers involved in sustainable water management projects. The project must be sponsored by one or more municipalities in the Canton of Valais.

When is it?

Applications are open until 15 September 2025.

How much is it?

Prizes worth a total of CHF 50,000 for the implementation of tangible solutions in the municipalities of the Canton of Valais.

Who is it?

The #prixalpiq is organised by Alpiq in partnership with the Association des communes concédantes du Valais.