A photovoltaic farm project on a drinking water reserve worries local residents

It provides drinking water supply to 300,000 inhabitants of Marseille and small neighboring towns. The Vallon dol reserve, fed by the waters of the Verdon, a torrent which has its source in the Alps, built in 1973 on the heights to the north of the city, will also soon supply electricity. After the green lights from the ARS (Regional Health Agency) and ANSES (National Agency for Food, Environmental and Occupational Health Safety), the prefecture granted a building permit in February for a floating photovoltaic farm project.

Ten of the seventeen hectares of this basin storing three million cubic meters of water, i.e. the equivalent of 3-4 days of total consumption in the Marseilles conurbation, according to a calculation by ANSES, will be able to be covered with solar panels. A first in France. Because if there are already floating solar energy farms, as in Peyrolles-en-Provence, north of Aix, this has so far never been carried out on a reservoir of water intended for consumption.

The hypothesis of stainless steel floats

This is what has drawn the attention of local residents and citizen groups, who are concerned about possible contamination of micro and nanoplastics that would pass through the filters of the treatment plant. “For the floats, 447 tonnes of polyethylene plastic should be used, a plastic that degrades in the sun. And the passage in organisms of micro and nanoplastics has been documented quite recently. Our fear is at this level, ”explains Philippe Musarella, doctor and president of the association for the preservation and animation of the green lung of Saint-Mitre, a neighboring district of Vallon Dol.

A fear fueled by the ANSES report, submitted in October 2020, which in its conclusions and recommendations draws attention in particular to the “drinking treatment stages which are not effective in treating organic pollutants which could possibly be relegated by the materials of the floating plant”.

However, these residents who have launched a petition “for the precautionary principle to apply” are not opposed to the project. Rather, they want to be a “proposal and monitoring force”. “It will be a first in France, and we must do something exemplary”, believes Philippe Musarella, who considers that there may be alternatives, such as stainless steel, to the use of plastic for the floats. “We are asking for the creation of a monitoring committee and to have the right to look at the specifications of the call for tenders”, he summarizes.

The wish seems to have been heard on the side of the Canal de Provence Company (SCP), concessionaire of the work and project leader 50/50 with renewable EDF. At least on the principle of a monitoring committee “which will be associated with collective citizens”, assures the SCP. She is less so about stainless steel. For the SCP “this solution does not present technical feasibility and the plastic complies with health regulations”. The call for tenders and its specifications, scheduled for autumn 2023, should confirm this.

Marseille monitors

The town hall of Marseille could also closely monitor these specifications. In a letter addressed to the prefect, the ARS, the ANSES and the project leaders (SCP and EDF), Sébastien Barles and Michèle Rubirola, elected ecologists from the city of Marseille delegates for energy transition and health, ask “the study of alternatives to plastic” and “additional analyzes with feedback from London and Singapore”, cities that have already experimented with such devices. They are also calling for “the lifting of business secrecy”, in particular to have access to the precise compositions of the plastics and additives used.

Float in stainless steel or plastic, this photovoltaic power station project, which is still awaiting the agreement of the Energy Regulation Commission – a simple formality a priori -, should inject into the network a power of 10 megawatt hours. The work could be completed by the end of 2024, for an amount that the SCP does not wish to communicate – especially since its financing plan, which could be eligible for public schemes, is not complete.

The SCP, which manages several hundred kilometers of canals and several structures, already produces electricity thanks to hydroelectric facilities. However, it hopes to quadruple, thanks to solar, its production capacities by 2027 to achieve energy autonomy. In this context, the kilometers of canals, with an exposure to the sun of Provence, present an untapped potential. Hoping that it is not an energy good for a health evil.

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