Le Figaro Bordeaux
Landes farmers did not wait for the declarations of the Head of State - who announced at the end of March his desire to reach 10% reuse of wastewater by 2030 - to prepare.
A wastewater reuse project is in the study phase by the Landes Chamber of Agriculture, and has been in the pipeline since 2019. The idea is to carry out a "substitution"
:
wastewater will no longer be discharged into the nature but treated and conveyed towards the cultures, and the farmers will not have any more to take in the river in summer.
While climate change is becoming more and more prevalent, water is a subject that is already causing many tensions, such as around the disputed project of mega-basins for storing drinking water in Sainte-Soline, in the Deux- Sevres.
In the Landes, the drought has led farmers to the streets of Mont-de-Marsan, to demand that their water withdrawal quotas be maintained.
To prepare for an increase in water shortages, the Landes Chamber of Agriculture is therefore carrying out this project aimed at irrigating nearly 1,000 hectares of Landes agricultural land from discharges from the wastewater treatment plant (Step) of Mont-de-Marsan.
"
This project has three interests, for the city, for farmers and for the environment
", explains Julien Rabe, water management adviser at the Chamber of Agriculture, in charge of this subject.
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An estimated cost of 20 million euros
"
The interest for the community of Mont-de-Marsan is to no longer discharge the effluent from the Step
", allowing "
not to risk polluting the river one day with an uncontrolled discharge
".
As for the farmers, “
they collect in an environment where there are water restrictions in the summer and where they may be prohibited from pumping
”.
This new water supply will therefore “
eliminate this major inconvenience
” suffered by the farmers.
Finally, "
by eliminating all pumping in the river in summer, the flow of the river will be much better than it was until now
".
The overall cost of the project is estimated at 20 million euros.
“
This is the first project in France where we are going to remove all of the water treated by the treatment plant.
The Step will no longer release a single cubic meter of water into the river
,” says Julien Rabe.
The idea is to replace a total of 42 river pumpings with those from the treatment plant.
21 farms will be affected by the transport of this waste water, made suitable for use in the agricultural environment.
After various processes, chlorine will in fact be injected into the water, "
at the same dose
as in drinking water
", to prevent bacteria from developing along the 17 kilometers of pipes between the treatment plant and the last tank.
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The impact will therefore be very positive for the river in the summer period.
Julien Rabe, water management adviser at the Chamber of Agriculture
Anticipating possible criticisms, in particular on the fact that the discharges from the Step would make it possible to put water back into nature, Julien Rabe specifies that it is a question of 50 liters per second which will be redirected from the Step to the crops. .
For comparison, the average annual flow in the river would be 1600 liters per second.
Stopping pumping in the summer would mean stopping taking around 300 liters per second from the river.
“
The impact will therefore be very positive for the river in the summer period
,” explains Julien Rabe.
This ambitious project for the department should however only see the light of day by 2026, regrets Julien Rabe, because “
big administrative tests are to be overcome
” to bring it to an end.
However, the water management consultant already has other ideas in mind for the department.
In particular, he wants to study the feasibility of recovering wastewater from the Step d'Hagetmau as well as that from a duck canning factory in Montaut.