In Toulouse, the fauna and flora revive in the middle of gravel pits stuffed with nitrocellulose
While waiting to be rid of the 4,200 tonnes of nitrocellulose from the First World War, which lie dormant at the bottom of the water, the four gravel pits near the Oncopole have once again become ecological paradises.
How to safely evacuate more than 4,200 tons of nitrocellulose, a propellant powder used in armament and produced during the First World War in the former national gunpowder factory, triggered in four artificial lakes, south of Toulouse near the current Oncopole? This is the mission entrusted to the Ministry of the Armed Forces, responsible for the ballast pits, an installation classified for the protection of the environment (ICPE), which undertook, last year, the rehabilitation of the site. While still working on the technical solutions which allow to initiate the complex operation of extraction of this explosive, harmless in the open air, planned in two years. A progress report was made at the end of November at the prefecture. The first results of the naturalist studies introduced in the spring of 2021 have shown that beyond the presence of new species in the area, red squirrels and birds in particular, the environmental richness is growing rapidly. “These studies are essential to properly measure the preservation actions to be carried out and to be able to now determine the intervention scenarios to clean up the site”, underlines Etienne Guyot, the prefect. The main objective is to allow rehabilitation while ensuring the complete safety of the interventions and preserving, in particular, the designated autochthonous plants, the numerous species, including reptiles and amphibians and their habitat and hunting areas.
Vigilance on biodiversity
In addition, studies related in particular to knowledge of the hydrogeological functioning of the site are in progress and should be completed in the first half of 2023. They are necessary to optimize its hydraulic management and control the conditions for carrying out destocking operations. In order to greatly limit ultimate waste as well as the environmental impact of rehabilitation operations, innovative treatment-removal processes are being examined. Three tests are currently being carried out over a short period of time and with a reduced volume of powder samples taken in order to compare these innovative processes with more conventional solutions, such as the heat treatment of powders. Full results are expected in the first half of next year. The prefect wanted to salute the experts from the Ministry of the Armed Forces for “the seriousness of their action”. François Chollet, vice-president of Toulouse Métropole in charge of the environment, welcomed the good news for fauna and flora. “But we remain vigilant for the continuation of the rehabilitation operations, in particular the preservation of this biodiversity”, he concluded.